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Triebold C, Barber J. The effect of the endothelial surface layer on cell-cell interactions in microvessel bifurcations. Biomech Model Mechanobiol 2024; 23:1695-1721. [PMID: 38847968 DOI: 10.1007/s10237-024-01863-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Accepted: 05/19/2024] [Indexed: 09/28/2024]
Abstract
Red blood cells (RBCs) carry oxygen and make up 40-45% of blood by volume in large vessels down to 10% or less in smaller capillaries. Because of their finite size and large volume fraction, they are heterogeneously distributed throughout the body. This is partially because RBCs are distributed or partitioned nonuniformly at diverging vessel bifurcations where blood flows from one vessel into two. Despite its increased recognition as an important player in the microvasculature, few studies have explored how the endothelial surface layer (ESL; a vessel wall coating) may affect partitioning and RBC dynamics at diverging vessel bifurcations. Here, we use a mathematical and computational model to consider how altering ESL properties, as can occur in pathological scenarios, change RBC partitioning, deformation, and penetration of the ESL. The two-dimensional finite element model considers pairs of cells, represented by interconnected viscoelastic elements, passing through an ESL-lined diverging vessel bifurcation. The properties of the ESL include the hydraulic resistivity and an osmotic pressure difference modeling how easily fluid flows through the ESL and how easily the ESL is structurally compressed, respectively. We find that cell-cell interaction leads to more uniform partitioning and greatly enhances the effects of ESL properties, especially for deformation and penetration. This includes the trend that increased hydraulic resistivity leads to more uniform partitioning, increased deformation, and decreased penetration. It also includes the trend that decreased osmotic pressure increases penetration.
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Affiliation(s)
- Carlson Triebold
- Department of Mathematical, Information and Computer Sciences, Point Loma Nazarene University, San Diego, USA.
| | - Jared Barber
- Department of Mathematical Sciences, Indiana University Indianapolis, Indianapolis, USA
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2
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Beukers AM, van Leeuwen ALI, Ibelings R, Tuip-de Boer AM, Bulte CSE, Eberl S, van den Brom CE. Lactated Ringers, albumin and mannitol as priming during cardiopulmonary bypass reduces pulmonary edema in rats compared with hydroxyethyl starch. Intensive Care Med Exp 2024; 12:78. [PMID: 39243290 PMCID: PMC11380653 DOI: 10.1186/s40635-024-00661-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 08/20/2024] [Indexed: 09/09/2024] Open
Abstract
BACKGROUND Endothelial disorders with edema formation and microcirculatory perfusion disturbances are common in cardiac surgery with cardiopulmonary bypass (CPB) and contribute to disturbed tissue oxygenation resulting in organ dysfunction. Albumin is protective for the endothelium and could be a useful additive to CPB circuit priming. Therefore, this study aimed to compare organ edema and microcirculatory perfusion in rats on CPB primed with lactated Ringers, albumin and mannitol (LR/albumin/mannitol) compared to 6% hydroxyethyl starch (HES). RESULTS Male rats were subjected to 75 min of CPB primed with either LR/albumin/mannitol or with 6% HES. Renal and lung edema were determined by wet/dry weight ratio. Pulmonary wet/dry weight ratio was lower in rats on CPB primed with LR/albumin/mannitol compared to HES (4.77 [4.44-5.25] vs. 5.33 [5.06-6.33], p = 0.032), whereas renal wet/dry weight ratio did not differ between groups (4.57 [4.41-4.75] vs. 4.51 [4.47-4.73], p = 0.813). Cremaster microcirculatory perfusion was assessed before, during and after CPB with intravital microscopy. CPB immediately impaired microcirculatory perfusion compared to baseline (LR/albumin/mannitol: 2 [1-7] vs. 14 [12-16] vessels per recording, p = 0.008; HES: 4 [2-6] vs. 12 [10-13] vessels per recording, p = 0.037), which persisted after weaning from CPB without differences between groups (LR/albumin/mannitol: 5 [1-9] vs. HES: 1 [0-4], p = 0.926). In addition, rats on CPB primed with LR/albumin/mannitol required less fluids to reach sufficient flow rates (0.5 [0.0-5.0] mL vs. 9 [4.5-10.0], p < 0.001) and phenylephrine (20 [0-40] µg vs. 90 [40-200], p = 0.004). Circulating markers for inflammation (interleukin 6 and 10), adhesion (ICAM-1), glycocalyx shedding (syndecan-1) and renal injury (NGAL) were determined by ELISA or Luminex. Circulating interleukin-6 (16 [13-25] vs. 33 [24-51] ng/mL, p = 0.006), interleukin-10 (434 [295-782] vs. 2120 [1309-3408] pg/ml, p < 0.0001), syndecan-1 (5 [3-7] vs. 15 [11-16] ng/mL, p < 0.001) and NGAL (555 [375-1078] vs. 2200 [835-3671] ng/mL, p = 0.008) were lower in rats on CPB primed with LR/albumin/mannitol compared to HES. CONCLUSION CPB priming with LR, albumin and mannitol resulted in less pulmonary edema, renal injury, inflammation and glycocalyx degradation compared to 6% HES. Furthermore, it enhanced hemodynamic stability compared with HES. Further research is needed to explore the specific role of albumin as a beneficial additive in CPB priming.
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Affiliation(s)
- Anne M Beukers
- Department of Anesthesiology, Amsterdam UMC, VU University, Amsterdam, The Netherlands
- Department of Cardiothoracic Surgery, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Anoek L I van Leeuwen
- Department of Anesthesiology, Amsterdam UMC, VU University, Amsterdam, The Netherlands
- Laboratory for Experimental Intensive Care and Anesthesiology (LEICA), Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Roselique Ibelings
- Department of Anesthesiology, Amsterdam UMC, VU University, Amsterdam, The Netherlands
- Laboratory for Experimental Intensive Care and Anesthesiology (LEICA), Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Anita M Tuip-de Boer
- Laboratory for Experimental Intensive Care and Anesthesiology (LEICA), Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Department of Intensive Care Medicine, Amsterdam UMC, University of Amsterdam, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands
| | - Carolien S E Bulte
- Department of Anesthesiology, Amsterdam UMC, VU University, Amsterdam, The Netherlands
| | - Susanne Eberl
- Department of Anesthesiology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Charissa E van den Brom
- Department of Anesthesiology, Amsterdam UMC, VU University, Amsterdam, The Netherlands.
- Laboratory for Experimental Intensive Care and Anesthesiology (LEICA), Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
- Department of Intensive Care Medicine, Amsterdam UMC, University of Amsterdam, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands.
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3
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Sun L, Wang L, Ye KX, Wang S, Zhang R, Juan Z, Feng L, Min S. Endothelial Glycocalyx in Aging and Age-related Diseases. Aging Dis 2023; 14:1606-1617. [PMID: 37196119 PMCID: PMC10529737 DOI: 10.14336/ad.2023.0131] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 01/31/2023] [Indexed: 05/19/2023] Open
Abstract
The worldwide population is aging exponentially, creating burdens to patients, their families and society. Increasing age is associated with higher risk of a wide range of chronic diseases, and aging of the vascular system is closely linked to the development of many age-related diseases. Endothelial glycocalyx is a layer of proteoglycan polymers on the surface of the inner lumen of blood vessels. It plays an important role in maintaining vascular homeostasis and protecting various organ functions. Endothelial glycocalyx loss happens through the aging process and repairing the endothelial glycocalyx may alleviate the symptoms of age-related diseases. Given the important role of the glycocalyx and its regenerative properties, it is posited that the endothelial glycocalyx may be a potential therapeutic target for aging and age-related diseases and repairing endothelial glycocalyx could play a role in the promotion of healthy aging and longevity. Here, we review the composition, function, shedding, and manifestation of the endothelial glycocalyx in aging and age-related diseases, as well as regeneration of endothelial glycocalyx.
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Affiliation(s)
- Lina Sun
- School of Anesthesiology, Weifang Medical University, Weifang, China.
- Department of Anesthesiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
| | - Lingyan Wang
- School of Anesthesiology, Weifang Medical University, Weifang, China.
| | - Kaisy Xinhong Ye
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
| | - Shoushi Wang
- School of Anesthesiology, Weifang Medical University, Weifang, China.
| | - Rui Zhang
- School of Anesthesiology, Weifang Medical University, Weifang, China.
| | - Zhaodong Juan
- School of Anesthesiology, Weifang Medical University, Weifang, China.
| | - Lei Feng
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
| | - Su Min
- Department of Anesthesiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
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Marsh PL, Moore EE, Moore HB, Bunch CM, Aboukhaled M, Condon SM, Al-Fadhl MD, Thomas SJ, Larson JR, Bower CW, Miller CB, Pearson ML, Twilling CL, Reser DW, Kim GS, Troyer BM, Yeager D, Thomas SG, Srikureja DP, Patel SS, Añón SL, Thomas AV, Miller JB, Van Ryn DE, Pamulapati SV, Zimmerman D, Wells B, Martin PL, Seder CW, Aversa JG, Greene RB, March RJ, Kwaan HC, Fulkerson DH, Vande Lune SA, Mollnes TE, Nielsen EW, Storm BS, Walsh MM. Iatrogenic air embolism: pathoanatomy, thromboinflammation, endotheliopathy, and therapies. Front Immunol 2023; 14:1230049. [PMID: 37795086 PMCID: PMC10546929 DOI: 10.3389/fimmu.2023.1230049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 07/12/2023] [Indexed: 10/06/2023] Open
Abstract
Iatrogenic vascular air embolism is a relatively infrequent event but is associated with significant morbidity and mortality. These emboli can arise in many clinical settings such as neurosurgery, cardiac surgery, and liver transplantation, but more recently, endoscopy, hemodialysis, thoracentesis, tissue biopsy, angiography, and central and peripheral venous access and removal have overtaken surgery and trauma as significant causes of vascular air embolism. The true incidence may be greater since many of these air emboli are asymptomatic and frequently go undiagnosed or unreported. Due to the rarity of vascular air embolism and because of the many manifestations, diagnoses can be difficult and require immediate therapeutic intervention. An iatrogenic air embolism can result in both venous and arterial emboli whose anatomic locations dictate the clinical course. Most clinically significant iatrogenic air emboli are caused by arterial obstruction of small vessels because the pulmonary gas exchange filters the more frequent, smaller volume bubbles that gain access to the venous circulation. However, there is a subset of patients with venous air emboli caused by larger volumes of air who present with more protean manifestations. There have been significant gains in the understanding of the interactions of fluid dynamics, hemostasis, and inflammation caused by air emboli due to in vitro and in vivo studies on flow dynamics of bubbles in small vessels. Intensive research regarding the thromboinflammatory changes at the level of the endothelium has been described recently. The obstruction of vessels by air emboli causes immediate pathoanatomic and immunologic and thromboinflammatory responses at the level of the endothelium. In this review, we describe those immunologic and thromboinflammatory responses at the level of the endothelium as well as evaluate traditional and novel forms of therapy for this rare and often unrecognized clinical condition.
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Affiliation(s)
- Phillip L. Marsh
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
| | - Ernest E. Moore
- Department of Surgery, Ernest E. Moore Shock Trauma Center at Denver Health and University of Colorado Health Sciences Center, Denver, CO, United States
| | - Hunter B. Moore
- University of Colorado Health Transplant Surgery - Anschutz Medical Campus, Aurora, CO, United States
| | - Connor M. Bunch
- Department of Emergency Medicine, Henry Ford Hospital, Detroit, MI, United States
| | - Michael Aboukhaled
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
| | - Shaun M. Condon
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
- Department of Emergency Medicine, Henry Ford Hospital, Detroit, MI, United States
| | | | - Samuel J. Thomas
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
| | - John R. Larson
- Department of Emergency Medicine, Goshen Health, Goshen, IN, United States
| | - Charles W. Bower
- Department of Emergency Medicine, Goshen Health, Goshen, IN, United States
| | - Craig B. Miller
- Department of Family Medicine, Saint Joseph Health System, Mishawaka, IN, United States
| | - Michelle L. Pearson
- Department of Family Medicine, Saint Joseph Health System, Mishawaka, IN, United States
| | | | - David W. Reser
- Department of Emergency Medicine, Goshen Health, Goshen, IN, United States
| | - George S. Kim
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
- Department of Emergency Medicine, Goshen Health, Goshen, IN, United States
| | - Brittany M. Troyer
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
- Department of Emergency Medicine, Goshen Health, Goshen, IN, United States
| | - Doyle Yeager
- Department of Emergency Medicine, Goshen Health, Goshen, IN, United States
| | - Scott G. Thomas
- Department of Trauma & Surgical Research Services, South Bend, IN, United States
| | - Daniel P. Srikureja
- Department of Trauma & Surgical Research Services, South Bend, IN, United States
| | - Shivani S. Patel
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
- Department of Emergency Medicine, Henry Ford Hospital, Detroit, MI, United States
| | - Sofía L. Añón
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
| | - Anthony V. Thomas
- Indiana University School of Medicine, South Bend, IN, United States
| | - Joseph B. Miller
- Department of Emergency Medicine, Henry Ford Hospital, Detroit, MI, United States
| | - David E. Van Ryn
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
- Department of Emergency Medicine, Goshen Health, Goshen, IN, United States
- Department of Emergency Medicine, Beacon Health System, Elkhart, IN, United States
| | - Saagar V. Pamulapati
- Department of Internal Medicine, Mercy Health Internal Medicine Residency Program, Rockford, IL, United States
| | - Devin Zimmerman
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
| | - Byars Wells
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
| | - Peter L. Martin
- Department of Emergency Medicine, Goshen Health, Goshen, IN, United States
| | - Christopher W. Seder
- Department of Cardiovascular and Thoracic Surgery, RUSH Medical College, Chicago, IL, United States
| | - John G. Aversa
- Department of Cardiovascular and Thoracic Surgery, RUSH Medical College, Chicago, IL, United States
| | - Ryan B. Greene
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
| | - Robert J. March
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
| | - Hau C. Kwaan
- Division of Hematology and Oncology, Department of Medicine, Northwestern University, Chicago, IL, United States
| | - Daniel H. Fulkerson
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
- Department of Trauma & Surgical Research Services, South Bend, IN, United States
| | - Stefani A. Vande Lune
- Department of Emergency Medicine, Naval Medical Center Portsmouth, Portsmouth, VA, United States
| | - Tom E. Mollnes
- Research Laboratory, Nordland Hospital, Bodø, Norway
- Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Department of Immunology, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Erik W. Nielsen
- Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Department of Anesthesia and Intensive Care Medicine, Surgical Clinic, Nordland Hospital, Bodø, Norway
- Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway
- Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway
| | - Benjamin S. Storm
- Department of Anesthesia and Intensive Care Medicine, Surgical Clinic, Nordland Hospital, Bodø, Norway
- Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway
- Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway
| | - Mark M. Walsh
- Department of Emergency Medicine, Saint Joseph Regional Medical Center, Mishawaka, IN, United States
- Indiana University School of Medicine, South Bend, IN, United States
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Zhao F, Tomita M, Dutta A. Operational Modal Analysis of Near-Infrared Spectroscopy Measure of 2-Month Exercise Intervention Effects in Sedentary Older Adults with Diabetes and Cognitive Impairment. Brain Sci 2023; 13:1099. [PMID: 37509027 PMCID: PMC10377417 DOI: 10.3390/brainsci13071099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/11/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023] Open
Abstract
The Global Burden of Disease Study (GBD 2019 Diseases and Injuries Collaborators) found that diabetes significantly increases the overall burden of disease, leading to a 24.4% increase in disability-adjusted life years. Persistently high glucose levels in diabetes can cause structural and functional changes in proteins throughout the body, and the accumulation of protein aggregates in the brain that can be associated with the progression of Alzheimer's Disease (AD). To address this burden in type 2 diabetes mellitus (T2DM), a combined aerobic and resistance exercise program was developed based on the recommendations of the American College of Sports Medicine. The prospectively registered clinical trials (NCT04626453, NCT04812288) involved two groups: an Intervention group of older sedentary adults with T2DM and a Control group of healthy older adults who could be either active or sedentary. The completion rate for the 2-month exercise program was high, with participants completing on an average of 89.14% of the exercise sessions. This indicated that the program was practical, feasible, and well tolerated, even during the COVID-19 pandemic. It was also safe, requiring minimal equipment and no supervision. Our paper presents portable near-infrared spectroscopy (NIRS) based measures that showed muscle oxygen saturation (SmO2), i.e., the balance between oxygen delivery and oxygen consumption in muscle, drop during bilateral heel rise task (BHR) and the 6 min walk task (6MWT) significantly (p < 0.05) changed at the post-intervention follow-up from the pre-intervention baseline in the T2DM Intervention group participants. Moreover, post-intervention changes from pre-intervention baseline for the prefrontal activation (both oxyhemoglobin and deoxyhemoglobin) showed statistically significant (p < 0.05, q < 0.05) effect at the right superior frontal gyrus, dorsolateral, during the Mini-Cog task. Here, operational modal analysis provided further insights into the 2-month exercise intervention effects on the very-low-frequency oscillations (<0.05 Hz) during the Mini-Cog task that improved post-intervention in the sedentary T2DM Intervention group from their pre-intervention baseline when compared to active healthy Control group. Then, the 6MWT distance significantly (p < 0.01) improved in the T2DM Intervention group at post-intervention follow-up from pre-intervention baseline that showed improved aerobic capacity and endurance. Our portable NIRS based measures have practical implications at the point of care for the therapists as they can monitor muscle and brain oxygenation changes during physical and cognitive tests to prescribe personalized physical exercise doses without triggering individual stress response, thereby, enhancing vascular health in T2DM.
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Affiliation(s)
- Fei Zhao
- Department of Rehabilitation Science, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY 14214, USA
| | - Machiko Tomita
- Department of Rehabilitation Science, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY 14214, USA
| | - Anirban Dutta
- School of Engineering, University of Lincoln, Lincoln LN67TS, UK
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6
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Franceković P, Gliemann L. Endothelial Glycocalyx Preservation-Impact of Nutrition and Lifestyle. Nutrients 2023; 15:nu15112573. [PMID: 37299535 DOI: 10.3390/nu15112573] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/08/2023] [Accepted: 05/11/2023] [Indexed: 06/12/2023] Open
Abstract
The endothelial glycocalyx (eGC) is a dynamic hair-like layer expressed on the apical surface of endothelial cells throughout the vascular system. This layer serves as an endothelial cell gatekeeper by controlling the permeability and adhesion properties of endothelial cells, as well as by controlling vascular resistance through the mediation of vasodilation. Pathogenic destruction of the eGC could be linked to impaired vascular function, as well as several acute and chronic cardiovascular conditions. Defining the precise functions and mechanisms of the eGC is perhaps the limiting factor of the missing link in finding novel treatments for lifestyle-related diseases such as atherosclerosis, type 2 diabetes, hypertension, and metabolic syndrome. However, the relationship between diet, lifestyle, and the preservation of the eGC is an unexplored territory. This article provides an overview of the eGC's importance for health and disease and describes perspectives of nutritional therapy for the prevention of the eGC's pathogenic destruction. It is concluded that vitamin D and omega-3 fatty acid supplementation, as well as healthy dietary patterns such as the Mediterranean diet and the time management of eating, might show promise for preserving eGC health and, thus, the health of the cardiovascular system.
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Affiliation(s)
- Paula Franceković
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen, Denmark
| | - Lasse Gliemann
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen, Denmark
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7
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Kaur G, Harris NR. Endothelial glycocalyx in retina, hyperglycemia, and diabetic retinopathy. Am J Physiol Cell Physiol 2023; 324:C1061-C1077. [PMID: 36939202 PMCID: PMC10125029 DOI: 10.1152/ajpcell.00188.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 02/28/2023] [Accepted: 03/16/2023] [Indexed: 03/21/2023]
Abstract
The endothelial glycocalyx (EG) is a meshlike network present on the apical surface of the endothelium. Membrane-bound proteoglycans, the major backbone molecules of the EG, consist of glycosaminoglycans attached to core proteins. In addition to maintaining the integrity of the endothelial barrier, the EG regulates inflammation and perfusion and acts as a mechanosensor. The loss of the EG can cause endothelial dysfunction and drive the progression of vascular diseases including diabetic retinopathy. Therefore, the EG presents a novel therapeutic target for treatment of vascular complications. In this review article, we provide an overview of the structure and function of the EG in the retina. Our particular focus is on hyperglycemia-induced perturbations in the glycocalyx structure in the retina, potential underlying mechanisms, and clinical trials studying protective treatments against degradation of the EG.
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Affiliation(s)
- Gaganpreet Kaur
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana, United States
| | - Norman R Harris
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana, United States
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8
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The Endothelial Glycocalyx and Retinal Hemodynamics. PATHOPHYSIOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY FOR PATHOPHYSIOLOGY 2022; 29:663-677. [PMID: 36548208 PMCID: PMC9785437 DOI: 10.3390/pathophysiology29040052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/20/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022]
Abstract
PURPOSE Previous studies suggest that the endothelial glycocalyx adds to vascular resistance, inhibits thrombosis, and is critical for regulating homogeneous blood flow and ensuring uniform red blood cell (RBC) distribution. However, these functions and consequences of the glycocalyx have not been examined in the retina. We hypothesize that the endothelial glycocalyx is a critical regulator of retinal hemodynamics and perfusion and decreases the propensity for retinal thrombus formation. METHODS Hyaluronidase and heparinase, which are endothelial glycocalyx-degrading enzymes, were infused into mice. Fluorescein isothiocyanate-dextran (2000 kDa) was injected to measure lumen diameter, while RBC velocity and distribution were measured using fluorescently labeled RBCs. The diameters and velocities were used to calculate retinal blood flow and shear rates. Mean circulation time was calculated by measuring the difference between arteriolar and venular mean transit times. Rose Bengal dye was infused, followed by illumination with a green light to induce thrombosis. RESULTS The acute infusion of hyaluronidase and heparinase led to significant increases in both arteriolar (7%) and venular (16%) diameters in the retina, with a tendency towards increased arteriolar velocity. In addition, the degradation caused a significant decrease in the venular shear rate (14%). The enzyme infusion resulted in substantial increases in total retinal blood flow (26%) and retinal microhematocrit but no changes in the mean circulation time through the retina. We also observed an enhanced propensity for retinal thrombus formation with the removal of the glycocalyx. CONCLUSIONS Our data suggest that acute degradation of the glycocalyx can cause significant changes in retinal hemodynamics, with increases in vessel diameter, blood flow, microhematocrit, pro-thrombotic conditions, and decreases in venular shear rate.
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Tomanek RJ. The coronary capillary bed and its role in blood flow and oxygen delivery: A review. Anat Rec (Hoboken) 2022; 305:3199-3211. [PMID: 35521832 PMCID: PMC9796134 DOI: 10.1002/ar.24951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 04/19/2022] [Accepted: 04/21/2022] [Indexed: 01/01/2023]
Abstract
The assumption that the coronary capillary blood flow is exclusively regulated by precapillary vessels is not supported by recent data. Rather, the complex coronary capillary bed has unique structural and geometric characteristics that invalidate many assumptions regarding red blood cell (RBC) transport, for example, data based on a single capillary or that increases in flow are the result of capillary recruitment. It is now recognized that all coronary capillaries are open and that their variations in flow are due to structural differences, local O2 demand and delivery, and variations in hematocrit. Recent data reveal that local mechanisms within the capillary bed regulate flow via signaling mechanisms involving RBC signaling and endothelial-associated pericytes that contract and relax in response to humoral and neural signaling. The discovery that pericytes respond to vasoactive signals (e.g., nitric oxide, phenylephrine, and adenosine) underscores the role of these cells in regulating capillary diameter and consequently RBC flux and oxygen delivery. RBCs also affect blood flow by sensing <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>P</mml:mi> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> and releasing nitric oxide to facilitate relaxation of pericytes and a consequential capillary dilation. New data indicate that these signaling mechanisms allow control of blood flow in specific coronary capillaries according to their oxygen requirements. In conclusion, mechanisms in the coronary capillary bed facilitate RBC density and transit time, hematocrit, blood flow and O2 delivery, factors that decrease capillary heterogeneity. These findings have important clinical implications for myocardial ischemia and infarction, as well as other vascular diseases.
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Affiliation(s)
- Robert J. Tomanek
- Department of Anatomy and Cell Biology, Carver College of MedicineUniversity of IowaIowa CityIAUSA
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10
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Affiliation(s)
- Mark A Chaney
- Department of Anesthesia and Critical Care, University of Chicago, Chicago, Illinois
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11
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Qiu Y, Buffonge S, Ramnath R, Jenner S, Fawaz S, Arkill KP, Neal C, Verkade P, White SJ, Hezzell M, Salmon AHJ, Suleiman MS, Welsh GI, Foster RR, Madeddu P, Satchell SC. Endothelial glycocalyx is damaged in diabetic cardiomyopathy: angiopoietin 1 restores glycocalyx and improves diastolic function in mice. Diabetologia 2022; 65:879-894. [PMID: 35211778 PMCID: PMC8960650 DOI: 10.1007/s00125-022-05650-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 10/28/2021] [Indexed: 12/28/2022]
Abstract
AIMS/HYPOTHESIS Diabetic cardiomyopathy (DCM) is a serious and under-recognised complication of diabetes. The first sign is diastolic dysfunction, which progresses to heart failure. The pathophysiology of DCM is incompletely understood but microcirculatory changes are important. Endothelial glycocalyx (eGlx) plays multiple vital roles in the microcirculation, including in the regulation of vascular permeability, and is compromised in diabetes but has not previously been studied in the coronary microcirculation in diabetes. We hypothesised that eGlx damage in the coronary microcirculation contributes to increased microvascular permeability and hence to cardiac dysfunction. METHODS We investigated eGlx damage and cardiomyopathy in mouse models of type 1 (streptozotocin-induced) and type 2 (db/db) diabetes. Cardiac dysfunction was determined by echocardiography. We obtained eGlx depth and coverage by transmission electron microscopy (TEM) on mouse hearts perfusion-fixed with glutaraldehyde and Alcian Blue. Perivascular oedema was assessed from TEM images by measuring the perivascular space area. Lectin-based fluorescence was developed to study eGlx in paraformaldehyde-fixed mouse and human tissues. The eGlx of human conditionally immortalised coronary microvascular endothelial cells (CMVECs) in culture was removed with eGlx-degrading enzymes before measurement of protein passage across the cell monolayer. The mechanism of eGlx damage in the diabetic heart was investigated by quantitative reverse transcription-PCR array and matrix metalloproteinase (MMP) activity assay. To directly demonstrate that eGlx damage disturbs cardiac function, isolated rat hearts were treated with enzymes in a Langendorff preparation. Angiopoietin 1 (Ang1) is known to restore eGlx and so was used to investigate whether eGlx restoration reverses diastolic dysfunction in mice with type 1 diabetes. RESULTS In a mouse model of type 1 diabetes, diastolic dysfunction (confirmed by echocardiography) was associated with loss of eGlx from CMVECs and the development of perivascular oedema, suggesting increased microvascular permeability. We confirmed in vitro that eGlx removal increases CMVEC monolayer permeability. We identified increased MMP activity as a potential mechanism of eGlx damage and we observed loss of syndecan 4 consistent with MMP activity. In a mouse model of type 2 diabetes we found a similar loss of eGlx preceding the development of diastolic dysfunction. We used isolated rat hearts to demonstrate that eGlx damage (induced by enzymes) is sufficient to disturb cardiac function. Ang1 restored eGlx and this was associated with reduced perivascular oedema and amelioration of the diastolic dysfunction seen in mice with type 1 diabetes. CONCLUSIONS/INTERPRETATION The association of CMVEC glycocalyx damage with diastolic dysfunction in two diabetes models suggests that it may play a pathophysiological role and the enzyme studies confirm that eGlx damage is sufficient to impair cardiac function. Ang1 rapidly restores the CMVEC glycocalyx and improves diastolic function. Our work identifies CMVEC glycocalyx damage as a potential contributor to the development of DCM and therefore as a therapeutic target.
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Affiliation(s)
- Yan Qiu
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK.
| | - Stanley Buffonge
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Raina Ramnath
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Sophie Jenner
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Sarah Fawaz
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Kenton P Arkill
- Biodiscovery Institute, Medicine, University of Nottingham, Nottingham, UK
| | - Chris Neal
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Paul Verkade
- School of Biochemistry, University of Bristol, Bristol, UK
| | - Stephen J White
- Department of Life Sciences, Manchester Metropolitan University, Manchester, UK
| | - Melanie Hezzell
- Bristol Veterinary School, University of Bristol, Langford, UK
| | - Andrew H J Salmon
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
- Renal Service, Specialist Medicine and Health of Older People, North Shore Hospital, Waitemata District Health Board, Takapuna, Auckland, New Zealand
| | - M-Saadeh Suleiman
- Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Gavin I Welsh
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Rebecca R Foster
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Paolo Madeddu
- Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Simon C Satchell
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, University of Bristol, Bristol, UK
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12
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Williams IM, Wasserman DH. Capillary Endothelial Insulin Transport: The Rate-limiting Step for Insulin-stimulated Glucose Uptake. Endocrinology 2022; 163:6462374. [PMID: 34908124 PMCID: PMC8758342 DOI: 10.1210/endocr/bqab252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Indexed: 11/19/2022]
Abstract
The rate-limiting step for skeletal muscle glucose uptake is transport from microcirculation to muscle interstitium. Capillary endothelium poses a barrier that delays the onset of muscle insulin action. Defining physiological barriers that control insulin access to interstitial space is difficult because of technical challenges that confront study of microscopic events in an integrated physiological system. Two physiological variables determine muscle insulin access. These are the number of perfused capillaries and the permeability of capillary walls to insulin. Disease states associated with capillary rarefaction are closely linked to insulin resistance. Insulin permeability through highly resistant capillary walls of muscle poses a significant barrier to insulin access. Insulin may traverse the endothelium through narrow intercellular junctions or vesicular trafficking across the endothelial cell. Insulin is large compared with intercellular junctions, making this an unlikely route. Transport by endothelial vesicular trafficking is likely the primary route of transit. Studies in vivo show movement of insulin is not insulin receptor dependent. This aligns with single-cell transcriptomics that show the insulin receptor is not expressed in muscle capillaries. Work in cultured endothelial cell lines suggest that insulin receptor activation is necessary for endothelial insulin transit. Controversies remain in the understanding of transendothelial insulin transit to muscle. These controversies closely align with experimental approaches. Control of circulating insulin accessibility to skeletal muscle is an area that remains ripe for discovery. Factors that impede insulin access to muscle may contribute to disease and factors that accelerate access may be of therapeutic value for insulin resistance.
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Affiliation(s)
- Ian M Williams
- Department of Molecular Physiology and Biophysics and Vanderbilt Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN 37232-0615, USA
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics and Vanderbilt Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN 37232-0615, USA
- Correspondence: David H. Wasserman, PhD, Light Hall Rm. 702, Vanderbilt University, Nashville, TN 37232-0615, USA.
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13
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Mendelson AA, Ho E, Scott S, Vijay R, Hunter T, Milkovich S, Ellis CG, Goldman D. Capillary module hemodynamics and mechanisms of blood flow regulation in skeletal muscle capillary networks: Experimental and computational analysis. J Physiol 2022; 600:1867-1888. [DOI: 10.1113/jp282342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 01/19/2022] [Indexed: 11/08/2022] Open
Affiliation(s)
- Asher A Mendelson
- Department of Medicine Section of Critical Care Medicine Rady Faculty of Health Sciences University of Manitoba Winnipeg Manitoba Canada
| | - Edward Ho
- Department of Medical Biophysics Schulich School of Medicine and Dentistry Western University London Ontario Canada
| | - Shayla Scott
- Department of Medical Biophysics Schulich School of Medicine and Dentistry Western University London Ontario Canada
| | - Raashi Vijay
- Department of Medical Biophysics Schulich School of Medicine and Dentistry Western University London Ontario Canada
| | - Timothy Hunter
- Department of Medical Biophysics Schulich School of Medicine and Dentistry Western University London Ontario Canada
| | - Stephanie Milkovich
- Department of Medical Biophysics Schulich School of Medicine and Dentistry Western University London Ontario Canada
- Robarts Research Institute London Ontario Canada
| | - Christopher G Ellis
- Department of Medical Biophysics Schulich School of Medicine and Dentistry Western University London Ontario Canada
- Robarts Research Institute London Ontario Canada
| | - Daniel Goldman
- Department of Medical Biophysics Schulich School of Medicine and Dentistry Western University London Ontario Canada
- School of Biomedical Engineering Western University London Ontario Canada
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14
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Cho JM, Ly K, Ly S, Park SK, Babu PVA, Balagurunathan K, Symons JD. Procedures to Evaluate the Role of Heparan Sulfate on the Reactivity of Resistance and Conductance Arteries Ex Vivo. Methods Mol Biol 2022; 2303:495-511. [PMID: 34626404 PMCID: PMC9700329 DOI: 10.1007/978-1-0716-1398-6_40] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Evidence is emerging that disruption of the endothelial glycocalyx might contribute importantly to arterial dysfunction in the context of diabetes. One approach to assess the integrity of the endothelium and the vascular smooth muscle cell layer, in the absence of neural, humoral, and mechanical influences, is by measuring arterial vasomotion ex vivo. Here we describe a procedure to assess non-receptor-mediated vasoconstriction, receptor-mediated vasoconstriction, and endothelium-dependent and -independent vasodilation, in resistance and conductance arteries pressurized to 60 mmHg. In addition to evaluating vasoreactivity using isobaric approaches, the same experimental set-up can be used to initiate a pressure gradient across the artery such that intraluminal, flow-mediated vasodilation can be measured. After recording endothelium-dependent vasodilation using isobaric or flow-mediated approaches, identical interventions can be completed in the presence of enzymes that cleave biologically active heparan sulfates into inactive disaccharide and oligosaccharide fragments to assess the contribution from: (a) endothelial-derived substances (e.g., nitric oxide via nitric oxide synthase inhibition); or (b) important components of the glycocalyx (e.g., removal of heparan sulfate via heparitinase III treatment). Here, we show that acute disruption of a predominant glycosaminoglycan i.e., heparan sulfate impairs intraluminal flow-mediated vasodilation in murine resistance arteries.
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Affiliation(s)
- Jae Min Cho
- Department of Nutrition and Integrative Physiology, Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - Kellsey Ly
- Department of Nutrition and Integrative Physiology, Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - Steven Ly
- Department of Nutrition and Integrative Physiology, Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - Seul-Ki Park
- Department of Nutrition and Integrative Physiology, Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - Pon Velayutham Anandh Babu
- Department of Nutrition and Integrative Physiology, Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - Kuberan Balagurunathan
- Departments of Biology, Bioengineering, and Medicinal Chemistry, University of Utah, Salt Lake City, UT, USA
| | - J David Symons
- Department of Nutrition and Integrative Physiology, Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA.
- Division of Endocrinology, Metabolism, and Diabetes, University of Utah, Salt Lake City, UT, USA.
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15
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Kaur G, Rogers J, Rashdan NA, Cruz-Topete D, Pattillo CB, Hartson SD, Harris NR. Hyperglycemia-induced effects on glycocalyx components in the retina. Exp Eye Res 2021; 213:108846. [PMID: 34801534 PMCID: PMC8665121 DOI: 10.1016/j.exer.2021.108846] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/10/2021] [Accepted: 11/12/2021] [Indexed: 11/19/2022]
Abstract
PURPOSE Diabetic retinopathy is a vision-threatening complication of diabetes characterized by endothelial injury and vascular dysfunction. The loss of the endothelial glycocalyx, a dynamic layer lining all endothelial cells, contributes to several microvascular pathologies, including an increase in vascular permeability, leukocyte plugging, and capillary occlusion, and may drive the progression of retinopathy. Previously, a significant decrease in glycocalyx thickness has been observed in diabetic retinas. However, the effects of diabetes on specific components of the retinal glycocalyx have not yet been studied. Therefore, the aim of our study was to investigate changes in synthesis, expression, and shedding of retinal glycocalyx components induced by hyperglycemia, which could provide a novel therapeutic target for diabetic retinopathy. METHODS Primary rat retinal microvascular endothelial cells (RRMECs) were grown under normal glucose (5 mM) or high-glucose (25 mM) conditions for 6 days. The mRNA and protein levels of the glycocalyx components were examined using qRT-PCR and Western blot analysis, respectively. Further, mass spectrometry was used to analyze protein intensities of core proteins. In addition, the streptozotocin-induced Type 1 diabetic rat model was used to study changes in the expression of the retinal glycocalyx in vivo. The shedding of the glycocalyx was studied in both culture medium and in plasma using Western blot analysis. RESULTS A significant increase in the shedding of syndecan-1 and CD44 was observed both in vitro and in vivo under high-glucose conditions. The mRNA levels of syndecan-3 were significantly lower in the RRMECs grown under high glucose conditions, whereas those of syndecan-1, syndecan-2, syndecan-4, glypican-1, glypican-3, and CD44 were significantly higher. The protein expression of syndecan-3 and glypican-1 in RRMECs was reduced considerably following exposure to high glucose, whereas that of syndecan-1 and CD44 increased significantly. In addition, mass spectrometry data also suggests a significant increase in syndecan-4 and a significant decrease in glypican-3 protein levels with high glucose stimulation. In vivo, our data also suggest a significant decrease in the mRNA transcripts of syndecan-3 and an increase in mRNA levels of glypican-1 and CD44 in the retinas of diabetic rats. The diabetic rats exhibited a significant reduction in the retinal expression of syndecan-3 and CD44. However, the expression of syndecan-1 and glypican-1 increased significantly in the diabetic retina. CONCLUSIONS One of the main findings of our study was the considerable diversity of glucose-induced changes in expression and shedding of various components of endothelial glycocalyx, for example, increased endothelial and retinal syndecan-1, but decreased endothelial and retinal syndecan-3. This indicates that the reported decrease in the retinal glycocalyx in diabetes in not a result of a non-specific shedding mechanism. Moreover, mRNA measurements indicated a similar diversity, with increases in endothelial and/or retinal levels of syndecan-1, glypican-1, and CD44, but a decrease for syndecan-3, with these increases in mRNA potentially a compensatory reaction to the overall loss of glycocalyx.
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Affiliation(s)
- Gaganpreet Kaur
- Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA
| | - Janet Rogers
- Oklahoma State University, OK, Department of Biochemistry and Molecular Biology, USA
| | - Nabil A Rashdan
- Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA
| | - Diana Cruz-Topete
- Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA
| | - Christopher B Pattillo
- Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA
| | - Steven D Hartson
- Oklahoma State University, OK, Department of Biochemistry and Molecular Biology, USA
| | - Norman R Harris
- Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA.
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16
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Galpayage Dona KNU, Hale JF, Salako T, Anandanatarajan A, Tran KA, DeOre BJ, Galie PA, Ramirez SH, Andrews AM. The Use of Tissue Engineering to Fabricate Perfusable 3D Brain Microvessels in vitro. Front Physiol 2021; 12:715431. [PMID: 34531761 PMCID: PMC8438211 DOI: 10.3389/fphys.2021.715431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 08/10/2021] [Indexed: 11/26/2022] Open
Abstract
Tissue engineering of the blood-brain barrier (BBB) in vitro has been rapidly expanding to address the challenges of mimicking the native structure and function of the BBB. Most of these models utilize 2D conventional microfluidic techniques. However, 3D microvascular models offer the potential to more closely recapitulate the cytoarchitecture and multicellular arrangement of in vivo microvasculature, and also can recreate branching and network topologies of the vascular bed. In this perspective, we discuss current 3D brain microvessel modeling techniques including templating, printing, and self-assembling capillary networks. Furthermore, we address the use of biological matrices and fluid dynamics. Finally, key challenges are identified along with future directions that will improve development of next generation of brain microvasculature models.
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Affiliation(s)
- Kalpani N Udeni Galpayage Dona
- Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Jonathan Franklin Hale
- Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Tobi Salako
- Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Akanksha Anandanatarajan
- Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Kiet A Tran
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ, United States
| | - Brandon J DeOre
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ, United States
| | - Peter Adam Galie
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ, United States
| | - Servio Heybert Ramirez
- Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States.,The Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States.,Shriners Hospitals Pediatric Research Center, Philadelphia, PA, United States
| | - Allison Michelle Andrews
- Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States.,The Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
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17
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Windberger U, Baroni P, Noirez L. Capillary-size flow of human blood plasma: Revealing hidden elasticity and scale dependence. J Biomed Mater Res A 2021; 110:298-303. [PMID: 34351058 DOI: 10.1002/jbm.a.37286] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 07/17/2021] [Accepted: 07/21/2021] [Indexed: 11/11/2022]
Abstract
The dynamical mechanical analysis of blood generally uses models inspired by conventional flows, assuming scale-independent homogeneous flows and without considering fluid-surface boundary interactions. The present experimental study highlights the relevance of using an approach in line with physiological reality providing a strong interaction between the fluid and the boundary interface. New dynamic properties of human blood plasma are found: a finite shear elastic response (solid-like property) is identified in nearly static conditions, which also depends on the scale (being reinforced at small scales). The elastic behavior is confirmed by the induction, without heat transfer, of local hot and cold thermodynamic states evidencing a thermo-mechanical coupling in blood plasma so far known only in elastic materials. This finding opens new routes for medical diagnosis and device fabrication.
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Affiliation(s)
- Ursula Windberger
- Center for Biomedical Research, Decentralized Biomedical Facilities, Medical University Vienna, Vienna, Austria
| | - Patrick Baroni
- Laboratoire Léon Brillouin (CEA-CNRS), University of Paris-Saclay, Gif-sur-Yvette, France
| | - Laurence Noirez
- Laboratoire Léon Brillouin (CEA-CNRS), University of Paris-Saclay, Gif-sur-Yvette, France
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18
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Maternal microvascular dysfunction during preeclamptic pregnancy. Clin Sci (Lond) 2021; 135:1083-1101. [PMID: 33960392 DOI: 10.1042/cs20200894] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/19/2021] [Accepted: 04/21/2021] [Indexed: 12/15/2022]
Abstract
Preeclampsia is a hypertensive disorder of pregnancy effecting ∼5-8% of pregnancies in the United States, and ∼8 million pregnancies worldwide. Preeclampsia is clinically diagnosed after the 20th week of gestation and is characterized by new onset hypertension accompanied by proteinuria and/or thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, or cerebral or visual symptoms. This broad definition emphasizes the heterogeneity of the clinical presentation of preeclampsia, but also underscores the role of the microvascular beds, specifically the renal, cerebral, and hepatic circulations, in the pathophysiology of the disease. While the diagnostic criteria for preeclampsia relies on the development of de novo hypertension and accompanying clinical symptoms after 20-week gestation, it is likely that subclinical dysfunction of the maternal microvascular beds occurs in parallel and may even precede the development of overt cardiovascular symptoms in these women. However, little is known about the physiology of the non-reproductive maternal microvascular beds during preeclampsia, and the mechanism(s) mediating microvascular dysfunction during preeclamptic pregnancy are largely unexplored in humans despite their integral role in the pathophysiology of the disease. Therefore, the purpose of this review is to provide a summary of the existing literature on maternal microvascular dysfunction during preeclamptic pregnancy by reviewing the functional evidence in humans, highlighting potential mechanisms, and providing recommendations for future work in this area.
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19
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Logsdon AF, Rhea EM, Reed M, Banks WA, Erickson MA. The neurovascular extracellular matrix in health and disease. Exp Biol Med (Maywood) 2021; 246:835-844. [PMID: 33302738 PMCID: PMC8719034 DOI: 10.1177/1535370220977195] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The blood-brain barrier (BBB) is a vital interface that supports normal brain functions. Endothelial cells (ECs) are the main component of the BBB and are highly specialized to govern the transfer of substances into brain. The EC lumen is enmeshed with an extracellular matrix (ECM), known as the endothelial glycocalyx layer (EGL). The lumen-facing EGL is primarily comprised of proteoglycans (PGs) and glycosaminoglycans (GAGs), which function as the first line of defense for blood-to-brain transfer of substances. Circulating factors must first penetrate the EGL before interacting with the EC. The abundance and composition of the PG and GAGs can dictate EGL function, and determine which circulating substances communicate with the ECs. The EGL can interact with circulating factors through physio-chemical interactions with the EC. Some disease states reveal a "thinning" of the EGL that may increase EC interactions with components of the systemic circulation and alter BBB function. EGL changes may also contribute to the cognitive complications of systemic diseases, such as sepsis and diabetes. For decades, researchers have measured how genetic and environmental factors influence the peripheral EGL constituents; however, much less is known about the neurovascular EGL. In this mini-review, we introduce components of the EGL and innovative ways to measure their abundance and composition that may contribute to BBB dysfunction.
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Affiliation(s)
- Aric F Logsdon
- Geriatrics Research Education and Clinical Center,
Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108,
USA
- Division of Gerontology and Geriatric Medicine,
Department of Medicine, University of Washington School of Medicine,
Seattle, WA 98159, USA
| | - Elizabeth M Rhea
- Geriatrics Research Education and Clinical Center,
Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108,
USA
- Division of Gerontology and Geriatric Medicine,
Department of Medicine, University of Washington School of Medicine,
Seattle, WA 98159, USA
| | - May Reed
- Geriatrics Research Education and Clinical Center,
Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108,
USA
- Division of Gerontology and Geriatric Medicine,
Department of Medicine, University of Washington School of Medicine,
Seattle, WA 98159, USA
| | - William A Banks
- Geriatrics Research Education and Clinical Center,
Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108,
USA
- Division of Gerontology and Geriatric Medicine,
Department of Medicine, University of Washington School of Medicine,
Seattle, WA 98159, USA
| | - Michelle A Erickson
- Geriatrics Research Education and Clinical Center,
Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108,
USA
- Division of Gerontology and Geriatric Medicine,
Department of Medicine, University of Washington School of Medicine,
Seattle, WA 98159, USA
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20
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Abstract
The blood-brain barrier (BBB) protects the central nervous system (CNS) from unregulated exposure to the blood and its contents. The BBB also controls the blood-to-brain and brain-to-blood permeation of many substances, resulting in nourishment of the CNS, its homeostatic regulation and communication between the CNS and peripheral tissues. The cells forming the BBB communicate with cells of the brain and in the periphery. This highly regulated interface changes with healthy aging. Here, we review those changes, starting with morphology and disruption. Transporter changes include those for amyloid beta peptide, glucose and drugs. Brain fluid dynamics, pericyte health and basement membrane and glycocalyx compositions are all altered with healthy aging. Carrying the ApoE4 allele leads to an acceleration of most of the BBB's age-related changes. We discuss how alterations in the BBB that occur with healthy aging reflect adaptation to the postreproductive phase of life and may affect vulnerability to age-associated diseases.
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21
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Brettner F, Heitzer M, Thiele F, Hulde N, Nussbaum C, Achatz S, Jacob M, Becker BF, Conzen P, Kilger E, Chappell D. Non-invasive evaluation of macro- and microhemodynamic changes during induction of general anesthesia – A prospective observational single-blinded trial. Clin Hemorheol Microcirc 2021; 77:1-16. [DOI: 10.3233/ch-190691] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: Hypotension and bradycardia are known side effects of general anesthesia, while little is known about further macro- and microhemodynamic changes during induction. Intriguing is furthermore, why some patients require no vasopressor medication to uphold mean arterial pressure, while others need vasopressor support. OBJECTIVE: Determination of macro- and microhemodynamic changes during induction of general anesthesia. METHODS: We enrolled 150 female adults scheduled for gynaecological surgery into this prospective observational, single-blinded trial. Besides routinely measuring heart rate (HR) and mean arterial blood pressure (MAP), the non-invasive technique of thoracic electrical bioimpedance was applied to measure cardiac output (CO), cardiac index (CI), stroke volume (SV), stroke volume variability (SVV) and index of myocardial contractility (ICON) before induction of anesthesia, 7 times during induction, and, finally, after surgery in the recovery room. Changes in microcirculation were assessed using sidestream dark field imaging to establish the perfused boundary region (PBR), a validated gauge of glycocalyx health. Comparisons were made with Friedman’s or Wilcoxon test for paired data, and with Mann-Whitney-U test for unpaired data, with post-hoc corrections for multiple measurements by the Holm-Bonferroni method. RESULTS: 83 patients did not need vasopressor support, whereas 67 patients required therapy (norepinephrine, atropine or cafedrine/theodrenaline) to elevate MAP values to ≥70mmHg during induction, 54 of these receiving norepinephrine (NE) alone. Pre-interventional (basal) values of CO, CI, ICON, SV and SVV were all significantly lower in the group of patients later requiring NE (p < 0.04), whereas HR and MAP were identical for both groups. HR, MAP and CO decreased from baseline to 12 min after induction of general anesthesia in both the patients without and those with NE support. Heart rate decreased significantly by about 25% in both groups (–19 to –21 bpm). The median individual decrease of MAP amounted to –26.7% (19.7/33.3, p < 0.001) and –26.1% (11.6/33.2, p < 0.001), respectively, whereas for CO it was –40.7% (34.1/50.1, p < 0.001) and –43.5% (34.8/48.7). While these relative changes did not differ between the two groups, in absolute values there were significantly greater decreases in CO, CI, SV and ICON in the group requiring NE. Noteably, NE did not restore ICON or the other cardiac parameters to levels approaching those of the group without NE. PBR was measured in a total of 84 patients compiled from both groups, there being no intergroup differences. It increased 6.4% (p < 0.001) from pre-induction to the end of the operation, indicative of damage to microvascular glycocalyx. CONCLUSION: Non-invasive determination of CO provides additional hemodynamic information during anesthesia, showing that induction results in a significant decrease not only of MAP but also of CO and other cardiac factors at all timepoints compared to baseline values. The decrease of CO was greater than that of MAP and, in contrast to MAP, did not respond to NE. There was also no sign of a positive inotropic effect of NE in this situation. Support of MAP by NE must consequently result from an increase in peripheral arterial resistance, posing a risk for oxygen supply to tissue. In addition, general anesthesia and the operative stimulus lead to an impairment of the microcirculation.
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Affiliation(s)
- Florian Brettner
- Department of Anaesthesiology, University Hospital of Munich (LMU), Munich, Germany
- Department of Anesthesiology and Intensive Care Medicine, Brothers of Mercy Hospital Munich, Munich, Germany
| | - Markus Heitzer
- Department of Anaesthesiology, University Hospital of Munich (LMU), Munich, Germany
| | - Friederike Thiele
- Department of Anaesthesiology, University Hospital of Munich (LMU), Munich, Germany
| | - Nikolai Hulde
- Department of Anaesthesiology, University Hospital of Munich (LMU), Munich, Germany
| | - Claudia Nussbaum
- Dr. von Hauner Children’s Hospital, University Hospital of Munich (LMU), Munich, Germany
| | - Stefan Achatz
- Department of Anaesthesiology, University Hospital of Munich (LMU), Munich, Germany
| | - Matthias Jacob
- Department of Anesthesiology, Intensive Care Medicine and Pain Medicine, Brothers of Mercy Hospital St. Elizabeth in Straubing, Straubing, Germany
| | - Bernhard F. Becker
- Walter-Brendel-Centre of Experimental Medicine, Ludwig-Maximilians-University Munich (LMU), Planegg-Martinsried, Germany
| | - Peter Conzen
- Department of Anaesthesiology, University Hospital of Munich (LMU), Munich, Germany
| | - Erich Kilger
- Department of Anaesthesiology, University Hospital of Munich (LMU), Munich, Germany
| | - Daniel Chappell
- Department of Anaesthesiology, University Hospital of Munich (LMU), Munich, Germany
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22
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Obesity and impaired barrier function after shock: A biomimetic in vitro model using microfluidics. J Trauma Acute Care Surg 2021; 89:544-550. [PMID: 32467464 DOI: 10.1097/ta.0000000000002804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Impaired microvascular perfusion in the obese patient has been linked to chronic adverse health consequences. The impact on acute illnesses including trauma, sepsis, and hemorrhagic shock (HS) is uncertain. Studies have shown that endothelial glycocalyx and vascular endothelial derangements are causally linked to perfusion abnormalities. Trauma and HS are also associated with impaired microvascular perfusion in which glycocalyx injury and endothelial dysfunction are sentinel events. We postulate that obesity may impact the adverse consequences of HS on the vascular barrier. This was studied in vivo in a biomimetic model of HS using microfluidic technology. METHODS Human umbilical vein endothelial cell monolayers were established in a microfluidic device. Cells were exposed to standard or biomimetic shock conditions (hypoxia plus epinephrine) followed by perfusion from plasma obtained from obese or nonobese subjects. Endothelial glycocalyx and endothelial cellular injury were then determined. RESULTS Plasma from nonobese patients completely reversed glycocalyx and endothelial vascular barrier injury. Plasma from obese patients was only partially protective and was associated with differences in adipokines and other substances in the plasma of these patients. CONCLUSION Our study supports that obesity impairs HS resuscitation. This may be due to microrheological differences between nonobese and obese individuals and may contribute to the poorer outcome in this patient population.
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23
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Pappelis K, Choritz L, Jansonius NM. Microcirculatory model predicts blood flow and autoregulation range in the human retina: in vivo investigation with laser speckle flowgraphy. Am J Physiol Heart Circ Physiol 2020; 319:H1253-H1273. [PMID: 32986964 DOI: 10.1152/ajpheart.00404.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In this study, we mathematically predict retinal vascular resistance (RVR) and retinal blood flow (RBF), we test predictions using laser speckle flowgraphy (LSFG), we estimate the range of vascular autoregulation, and we examine the relationship of RBF with the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC). Fundus, optical coherence tomography (OCT), and OCT-angiography images, systolic/diastolic blood pressure (SBP/DBP), and intraocular pressure (IOP) measurements were obtained from 36 human subjects. We modeled two circulation markers (RVR and RBF) and estimated individualized lower/higher autoregulation limits (LARL/HARL), using retinal vessel calibers, fractal dimension, perfusion pressure, and population-based hematocrit values. Quantitative LSFG waveforms were extracted from vessels of the same eyes, before and during IOP elevation. LSFG metrics explained most variance in RVR (R2 = 0.77/P = 6.9·10-9) and RBF (R2 = 0.65/P = 1.0·10-6), suggesting that the markers strongly reflect blood flow physiology. Higher RBF was associated with thicker RNFL (P = 4.0·10-4) and GCC (P = 0.003), thus also verifying agreement with structural measurements. LARL was at SBP/DBP of 105/65 mmHg for the average subject without arterial hypertension and at 115/75 mmHg for the average hypertensive subject. Moreover, during IOP elevation, changes in RBF were more pronounced than changes in RVR. These observations physiologically imply that healthy subjects are already close to LARL, thus prone to hypoperfusion. In conclusion, we modeled two clinical markers and described a novel method to predict individualized autoregulation limits. These findings could improve understanding of retinal perfusion and pave the way for personalized intervention decisions, when treating patients with coexisting ophthalmic and cardiovascular pathologies.NEW & NOTEWORTHY We describe and test a new approach to quantify retinal blood flow, based on standard clinical examinations and imaging techniques, linked together with a physiological model. We use these findings to generate individualized estimates of the autoregulation range. We provide evidence that healthy subjects are closer to the lower autoregulation limit than thought before. This suggests that some retinas are less prepared to withstand hypoperfusion, even after small intraocular pressure rises or blood pressure drops.
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Affiliation(s)
- Konstantinos Pappelis
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Research School of Behavioural and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands
| | - Lars Choritz
- University Eye Clinic, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Nomdo M Jansonius
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Research School of Behavioural and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands
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24
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Wright WS, Eshaq RS, Lee M, Kaur G, Harris NR. Retinal Physiology and Circulation: Effect of Diabetes. Compr Physiol 2020; 10:933-974. [PMID: 32941691 PMCID: PMC10088460 DOI: 10.1002/cphy.c190021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In this article, we present a discussion of diabetes and its complications, including the macrovascular and microvascular effects, with the latter of consequence to the retina. We will discuss the anatomy and physiology of the retina, including aspects of metabolism and mechanisms of oxygenation, with the latter accomplished via a combination of the retinal and choroidal blood circulations. Both of these vasculatures are altered in diabetes, with the retinal circulation intimately involved in the pathology of diabetic retinopathy. The later stages of diabetic retinopathy involve poorly controlled angiogenesis that is of great concern, but in our discussion, we will focus more on several alterations in the retinal circulation occurring earlier in the progression of disease, including reductions in blood flow and a possible redistribution of perfusion that may leave some areas of the retina ischemic and hypoxic. Finally, we include in this article a more recent area of investigation regarding the diabetic retinal vasculature, that is, the alterations to the endothelial surface layer that normally plays a vital role in maintaining physiological functions. © 2020 American Physiological Society. Compr Physiol 10:933-974, 2020.
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Affiliation(s)
- William S Wright
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, South Carolina, USA
| | - Randa S Eshaq
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Minsup Lee
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Gaganpreet Kaur
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Norman R Harris
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
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25
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Abushamat LA, McClatchey PM, Scalzo RL, Schauer I, Huebschmann AG, Nadeau KJ, Liu Z, Regensteiner JG, Reusch JEB. Mechanistic Causes of Reduced Cardiorespiratory Fitness in Type 2 Diabetes. J Endocr Soc 2020; 4:bvaa063. [PMID: 32666009 PMCID: PMC7334033 DOI: 10.1210/jendso/bvaa063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 06/04/2020] [Indexed: 02/06/2023] Open
Abstract
Type 2 diabetes (T2D) has been rising in prevalence in the United States and worldwide over the past few decades and contributes to significant morbidity and premature mortality, primarily due to cardiovascular disease (CVD). Cardiorespiratory fitness (CRF) is a modifiable cardiovascular (CV) risk factor in the general population and in people with T2D. Young people and adults with T2D have reduced CRF when compared with their peers without T2D who are similarly active and of similar body mass index. Furthermore, the impairment in CRF conferred by T2D is greater in women than in men. Various factors may contribute to this abnormality in people with T2D, including insulin resistance and mitochondrial, vascular, and cardiac dysfunction. As proof of concept that understanding the mediators of impaired CRF in T2D can inform intervention, we previously demonstrated that an insulin sensitizer improved CRF in adults with T2D. This review focuses on how contributing factors influence CRF and why they may be compromised in T2D. Functional exercise capacity is a measure of interrelated systems biology; as such, the contribution of derangement in each of these factors to T2D-mediated impairment in CRF is complex and varied. Therefore, successful approaches to improve CRF in T2D should be multifaceted and individually designed. The current status of this research and future directions are outlined.
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Affiliation(s)
- Layla A Abushamat
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | | | - Rebecca L Scalzo
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Rocky Mountain Regional VA, Aurora, Colorado.,Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Irene Schauer
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Rocky Mountain Regional VA, Aurora, Colorado.,Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Amy G Huebschmann
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Kristen J Nadeau
- Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Zhenqi Liu
- Department of Medicine, University of Virginia, Charlottesville, Virginia
| | - Judith G Regensteiner
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Jane E B Reusch
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Rocky Mountain Regional VA, Aurora, Colorado.,Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
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26
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Goulding RP, Roche DM, Scott SN, Koga S, Weston PJ, Marwood S. Limitations to exercise tolerance in type 1 diabetes: the role of pulmonary oxygen uptake kinetics and priming exercise. J Appl Physiol (1985) 2020; 128:1299-1309. [PMID: 32213117 DOI: 10.1152/japplphysiol.00892.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We compared the time constant (τV̇O2) of the fundamental phase of pulmonary oxygen uptake (V̇o2) kinetics between young adult men with type 1 diabetes and healthy control subjects. We also assessed the impact of priming exercise on τV̇O2, critical power, and muscle deoxygenation in a subset of participants with type 1 diabetes. Seventeen men with type 1 diabetes and 17 healthy male control subjects performed moderate-intensity exercise to determine τV̇O2. A subset of seven participants with type 1 diabetes performed an additional eight visits, in which critical power, τV̇O2, and muscle deoxyhemoglobin + myoglobin ([HHb+Mb], via near-infrared spectroscopy) kinetics (described by a time constant, τ[HHb+Mb]) were determined with (PRI) and without (CON) a prior 6-min bout of heavy exercise. τV̇O2 was greater in participants with type 1 diabetes compared with control subjects (type 1 diabetes 50 ± 13 vs. control 32 ± 12 s; P < 0.001). Critical power was greater in PRI compared with CON (PRI 161 ± 25 vs. CON 149 ± 22 W; P < 0.001), whereas τV̇O2 (PRI 36 ± 15 vs. CON 50 ± 21 s; P = 0.006) and τ[HHb+Mb] (PRI 10 ± 5 vs. CON 17 ± 11 s; P = 0.037) were reduced in PRI compared with CON. Type 1 diabetes patients showed slower pulmonary V̇o2 kinetics compared with control subjects; priming exercise speeded V̇o2 and [HHb + Mb] kinetics and increased critical power in a subgroup with type 1 diabetes. These data therefore represent the first characterization of the power-duration relationship in type 1 diabetes and the first experimental evidence that τV̇O2 is an independent determinant of critical power in this population.NEW & NOTEWORTHY Patients with type 1 diabetes demonstrated slower oxygen uptake (V̇o2) kinetics compared with healthy control subjects. Furthermore, a prior bout of high-intensity exercise speeded V̇o2 kinetics and increased critical power in people with type 1 diabetes. Prior exercise speeded muscle deoxygenation kinetics, indicating that V̇o2 kinetics in type 1 diabetes are limited primarily by oxygen extraction and/or intracellular factors. These findings highlight the potential for interventions that decrease metabolic inertia for enhancing exercise tolerance in this condition.
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Affiliation(s)
- Richie P Goulding
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom.,Japan Society for Promotion of Science, Tokyo, Japan.,Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Denise M Roche
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom
| | - Sam N Scott
- University Department of Diabetes, Endocrinology, Nutritional Medicine, and Metabolism, University Hospital and University of Bern, Bern, Switzerland.,Team Novo Nordisk Professional Cycling Team, Atlanta, Georgia
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Philip J Weston
- Royal Liverpool and Broadgreen University Hospitals NHS Trust, Liverpool, United Kingdom
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom
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27
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Harris NR, Leskova W, Kaur G, Eshaq RS, Carter PR. Blood flow distribution and the endothelial surface layer in the diabetic retina. Biorheology 2020; 56:181-189. [PMID: 30958328 PMCID: PMC10082436 DOI: 10.3233/bir-180200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Diabetic retinopathy is known as a microvascular complication of hyperglycemia, with a breakdown of the blood-retinal barrier, loss of pericytes, formation of microhemorrhages, early decreases in perfusion and areas of ischemia, with the latter speculated to induce the eventual proliferative, angiogenic phase of the disease. Our animal models of diabetic retinopathy demonstrate similar decreases in retinal blood flow as seen in the early stages of diabetes in humans. Our studies also show an alteration in the retinal distribution of red blood cells, with the deep capillary layer receiving a reduced fraction, and with flow being diverted more towards the superficial vascular layer. Normal red blood cell distribution is dependent on the presence of the endothelial surface layer, specifically the glycocalyx, which has been reported to be partially lost in the diabetic retina of both humans and animals. This review addresses these two phenomena in diabetes: altered perfusion patterns and loss of the glycocalyx, with a possible connection between the two.
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Affiliation(s)
- Norman R Harris
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Wendy Leskova
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Gaganpreet Kaur
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Randa S Eshaq
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Patsy R Carter
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
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28
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McClatchey PM, Williams IM, Xu Z, Mignemi NA, Hughey CC, McGuinness OP, Beckman JA, Wasserman DH, Poole DC, Akerstrom T, Goldman D, Fraser GM, Ellis CG. Reply to Letter to the Editor: Perfusion controls muscle glucose uptake by altering the rate of glucose dispersion in vivo. Am J Physiol Endocrinol Metab 2020; 318:E313-E317. [PMID: 32068464 DOI: 10.1152/ajpendo.00508.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- P Mason McClatchey
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Ian M Williams
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Zhengeng Xu
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Nicholas A Mignemi
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Curtis C Hughey
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Owen P McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Joshua A Beckman
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - David C Poole
- Departments of Anatomy & Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Thorbjorn Akerstrom
- Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Daniel Goldman
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada
| | - Graham M Fraser
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland St. John's, Newfoundland, Canada
| | - Christopher G Ellis
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada
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29
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McMahon TJ. Red Blood Cell Deformability, Vasoactive Mediators, and Adhesion. Front Physiol 2019; 10:1417. [PMID: 31803068 PMCID: PMC6873820 DOI: 10.3389/fphys.2019.01417] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 11/01/2019] [Indexed: 01/16/2023] Open
Abstract
Healthy red blood cells (RBCs) deform readily in response to shear stress in the circulation, facilitating their efficient passage through capillaries. RBCs also export vasoactive mediators in response to deformation and other physiological and pathological stimuli. Deoxygenation of RBC hemoglobin leads to the export of vasodilator and antiadhesive S-nitrosothiols (SNOs) and adenosine triphosphate (ATP) in parallel with oxygen transport in the respiratory cycle. Together, these mediated responses to shear stress and oxygen offloading promote the efficient flow of blood cells and in turn optimize oxygen delivery. In diseases including sickle cell anemia and conditions including conventional blood banking, these adaptive functions may be compromised as a result, for example, of limited RBC deformability, impaired mediator formation, or dysfunctional mediator export. Ongoing work, including single cell approaches, is examining relevant mechanisms and remedies in health and disease.
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Affiliation(s)
- Timothy J McMahon
- Durham VA Medical Center, Duke University, Durham, NC, United States
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30
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Erdener ŞE, Dalkara T. Small Vessels Are a Big Problem in Neurodegeneration and Neuroprotection. Front Neurol 2019; 10:889. [PMID: 31474933 PMCID: PMC6707104 DOI: 10.3389/fneur.2019.00889] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 08/01/2019] [Indexed: 12/11/2022] Open
Abstract
The cerebral microcirculation holds a critical position to match the high metabolic demand by neuronal activity. Functionally, microcirculation is virtually inseparable from other nervous system cells under both physiological and pathological conditions. For successful bench-to-bedside translation of neuroprotection research, the role of microcirculation in acute and chronic neurodegenerative disorders appears to be under-recognized, which may have contributed to clinical trial failures with some neuroprotectants. Increasing data over the last decade suggest that microcirculatory impairments such as endothelial or pericyte dysfunction, morphological irregularities in capillaries or frequent dynamic stalls in blood cell flux resulting in excessive heterogeneity in capillary transit may significantly compromise tissue oxygen availability. We now know that ischemia-induced persistent abnormalities in capillary flow negatively impact restoration of reperfusion after recanalization of occluded cerebral arteries. Similarly, microcirculatory impairments can accompany or even precede neural loss in animal models of several neurodegenerative disorders including Alzheimer's disease. Macrovessels are relatively easy to evaluate with radiological or experimental imaging methods but they cannot faithfully reflect the downstream microcirculatory disturbances, which may be quite heterogeneous across the tissue at microscopic scale and/or happen fast and transiently. The complexity and size of the elements of microcirculation, therefore, require utilization of cutting-edge imaging techniques with high spatiotemporal resolution as well as multidisciplinary team effort to disclose microvascular-neurodegenerative connection and to test treatment approaches to advance the field. Developments in two photon microscopy, ultrafast ultrasound, and optical coherence tomography provide valuable experimental tools to reveal those microscopic events with high resolution. Here, we review the up-to-date advances in understanding of the primary microcirculatory abnormalities that can result in neurodegenerative processes and the combined neurovascular protection approaches that can prevent acute as well as chronic neurodegeneration.
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Affiliation(s)
- Şefik Evren Erdener
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Turgay Dalkara
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey.,Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
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31
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Wu D, Birukov K. Endothelial Cell Mechano-Metabolomic Coupling to Disease States in the Lung Microvasculature. Front Bioeng Biotechnol 2019; 7:172. [PMID: 31380363 PMCID: PMC6658821 DOI: 10.3389/fbioe.2019.00172] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/03/2019] [Indexed: 12/15/2022] Open
Abstract
Lungs are the most vascular part of humans, accepting the totality of cardiac output in a volume much smaller than the body itself. Due to this cardiac output, the lung microvasculature is subject to mechanical forces including shear stress and cyclic stretch that vary with the cardiac and breathing cycle. Vessels are surrounded by extracellular matrix which dictates the stiffness which endothelial cells also sense and respond to. Shear stress, stiffness, and cyclic stretch are known to influence endothelial cell state. At high shear stress, endothelial cells exhibit cell quiescence marked by low inflammatory markers and high nitric oxide synthesis, whereas at low shear stress, endothelial cells are thought to "activate" into a pro-inflammatory state and have low nitric oxide. Shear stress' profound effect on vascular phenotype is most apparent in the arterial vasculature and in the pathophysiology of vascular inflammation. To conduct the flow of blood from the right heart, the lung microvasculature must be rigid yet compliant. It turns out that excessive substrate rigidity or stiffness is important in the development of pulmonary hypertension and chronic fibrosing lung diseases via excessive cell proliferation or the endothelial-mesenchymal transition. Recently, a new body of literature has evolved that couples mechanical sensing to endothelial phenotypic changes through metabolic signaling in clinically relevant contexts such as pulmonary hypertension, lung injury syndromes, as well as fibrosis, which is the focus of this review. Stretch, like flow, has profound effect on endothelial phenotype; metabolism studies due to stretch are in their infancy.
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Affiliation(s)
- David Wu
- Section of Pulmonary and Critical Care, Department of Medicine, University of Chicago, Chicago, IL, United States
| | - Konstantin Birukov
- Department of Anesthesia, University of Maryland, Baltimore, MD, United States
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32
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Diebel LN, Liberati DM. Red blood cell storage and adhesion to vascular endothelium under normal or stress conditions: An in vitro microfluidic study. J Trauma Acute Care Surg 2019; 86:943-951. [PMID: 31124891 DOI: 10.1097/ta.0000000000002239] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND Observational studies have identified an association between duration of red blood cell (RBC) storage and adverse outcomes in trauma. Hemorrhagic shock (HS) leads to impaired tissue perfusion which is associated with endothelial cell glycocalyx (eGC) shedding. Adhesion of stored RBC to the vascular endothelium has been shown to lead to impaired perfusion in the microcirculation and contribute to organ failure and poor outcome. The role of either or both of the EC and RBC glycocalyx in this process is unknown and was studied in an in vitro model. METHODS Human umbilical vein endothelial cells were perfused in a microfluidic device with RBC solutions from fresh, less than 14-day or longer than 21-day storage. In some experiments, the HS microenvironment was simulated by hypoxia-reoxygenation (H/R) and epinephrine (Epi) in the perfusion experiments. Measurements obtained included endothelial cell (EC) and RBC glycocalyx and RBC adherence to human umbilical vein endothelial cell monolayers at variable shear rates. RESULTS Endothelial cell glycocalyx and RBC glycocalyx dimensions were reduced by H/R and Epi and storage duration respectively. Red blood cell adherence to the endothelium was increased by H/R + Epi treatment and duration of RBC storage. CONCLUSION Our data may help explain some of the remaining discrepancies regarding the impact of RBC storage duration on outcomes in the trauma population. Consideration of the integrity of the EC and RBC glycocalyx may guide future transfusion strategies in the trauma population. The microfluidic device system platform may offer a high throughput modality to study emerging therapies to mitigate adverse consequence of RBC storage duration on the perfused endothelium in the trauma setting.
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Affiliation(s)
- Lawrence N Diebel
- From the Michael and Marian Ilitch Department of Surgery (L.N.D., D.M.L.), Wayne State University, Detroit, Michigan
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33
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Machin DR, Phuong TT, Donato AJ. The role of the endothelial glycocalyx in advanced age and cardiovascular disease. Curr Opin Pharmacol 2019; 45:66-71. [PMID: 31112922 DOI: 10.1016/j.coph.2019.04.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 04/15/2019] [Indexed: 12/24/2022]
Abstract
The endothelial glycocalyx is a gel-like structure that is bound to the luminal surface of the vascular endothelium. At the interface between flowing blood and endothelial cells, the glycocalyx has several functions that are critical for the maintenance of a healthy vasculature, particularly in regard to the vascular endothelium. Within the vasculature, the glycocalyx modulates vascular resistance to maintain blood flow homogeneity in the microcirculation, mechanotransduces fluid shear stress to the endothelium, and buffers endothelial cells from plasma oxidants, cytokines, and circulating immune cells. In advanced age and cardiovascular disease (CVD), the glycocalyx is deteriorated. Moreover, glycocalyx deterioration may precede traditional measurements of age-related vascular dysfunction, such as impaired endothelium-dependent dilation and large artery stiffness, suggesting that a deteriorated glycocalyx could initiate age-related CVD pathology.
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Affiliation(s)
- Daniel R Machin
- University of Utah, Department of Internal Medicine, Division of Geriatrics, Salt Lake City, UT, United States
| | - Tam Tt Phuong
- University of Utah, Department of Internal Medicine, Division of Geriatrics, Salt Lake City, UT, United States
| | - Anthony J Donato
- University of Utah, Department of Internal Medicine, Division of Geriatrics, Salt Lake City, UT, United States; Veterans Affairs Medical Center-Salt Lake City, Geriatrics Research Education and Clinical Center, Salt Lake City, UT, United States.
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34
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Fang Y, Wu D, Birukov KG. Mechanosensing and Mechanoregulation of Endothelial Cell Functions. Compr Physiol 2019; 9:873-904. [PMID: 30873580 PMCID: PMC6697421 DOI: 10.1002/cphy.c180020] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Vascular endothelial cells (ECs) form a semiselective barrier for macromolecules and cell elements regulated by dynamic interactions between cytoskeletal elements and cell adhesion complexes. ECs also participate in many other vital processes including innate immune reactions, vascular repair, secretion, and metabolism of bioactive molecules. Moreover, vascular ECs represent a unique cell type exposed to continuous, time-dependent mechanical forces: different patterns of shear stress imposed by blood flow in macrovasculature and by rolling blood cells in the microvasculature; circumferential cyclic stretch experienced by the arterial vascular bed caused by heart propulsions; mechanical stretch of lung microvascular endothelium at different magnitudes due to spontaneous respiration or mechanical ventilation in critically ill patients. Accumulating evidence suggests that vascular ECs contain mechanosensory complexes, which rapidly react to changes in mechanical loading, process the signal, and develop context-specific adaptive responses to rebalance the cell homeostatic state. The significance of the interactions between specific mechanical forces in the EC microenvironment together with circulating bioactive molecules in the progression and resolution of vascular pathologies including vascular injury, atherosclerosis, pulmonary edema, and acute respiratory distress syndrome has been only recently recognized. This review will summarize the current understanding of EC mechanosensory mechanisms, modulation of EC responses to humoral factors by surrounding mechanical forces (particularly the cyclic stretch), and discuss recent findings of magnitude-specific regulation of EC functions by transcriptional, posttranscriptional and epigenetic mechanisms using -omics approaches. We also discuss ongoing challenges and future opportunities in developing new therapies targeting dysregulated mechanosensing mechanisms to treat vascular diseases. © 2019 American Physiological Society. Compr Physiol 9:873-904, 2019.
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Affiliation(s)
- Yun Fang
- Department of Medicine, University of Chicago, Chicago, Illinois, USA,Correspondence to
| | - David Wu
- Department of Medicine, University of Chicago, Chicago, Illinois, USA
| | - Konstantin G. Birukov
- Department of Anesthesiology, University of Maryland Baltimore School of Medicine, Baltimore, Maryland, USA
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Dekker NAM, Veerhoek D, Koning NJ, van Leeuwen ALI, Elbers PWG, van den Brom CE, Vonk ABA, Boer C. Postoperative microcirculatory perfusion and endothelial glycocalyx shedding following cardiac surgery with cardiopulmonary bypass. Anaesthesia 2019; 74:609-618. [PMID: 30687934 PMCID: PMC6590376 DOI: 10.1111/anae.14577] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2018] [Indexed: 12/16/2022]
Abstract
We investigated microcirculatory perfusion disturbances following cardiopulmonary bypass in the early postoperative period and whether the course of these disturbances mirrored restoration of endothelial glycocalyx integrity. We performed sublingual sidestream dark field imaging of the microcirculation during the first three postoperative days in patients who had undergone on‐pump coronary artery bypass graft surgery. We calculated the perfused vessel density, proportion of perfused vessels and perfused boundary region. Plasma was obtained to measure heparan sulphate and syndecan‐1 levels as glycocalyx shedding markers. We recruited 17 patients; the mean (SD) duration of non‐pulsatile cardiopulmonary bypass was 103 (18) min, following which 491 (29) ml autologous blood was transfused through cell salvage. Cardiopulmonary bypass immediately decreased both microcirculatory perfused vessel density; 11 (3) vs. 16 (4) mm.mm−2, p = 0.052 and the proportion of perfused vessels; 92 (5) vs. 69 (9) %, p < 0.0001. The proportion of perfused vessels did not increase after transfusion of autologous salvaged blood following cardiopulmonary bypass; 72 (7) %, p = 0.19 or during the first three postoperative days; 71 (5) %, p < 0.0001. The perfused boundary region increased after cardiopulmonary bypass; 2.2 (0.3) vs. 1.9 (0.3) μm, p = 0.037 and during the first three postoperative days; 2.4 (0.3) vs. 1.9 (0.3) μm, p = 0.003. Increased plasma heparan sulphate levels were inversely associated with the proportion of perfused vessels during cardiopulmonary bypass; R = −0.49, p = 0.02. Plasma syndecan‐1 levels were inversely associated with the proportion of perfused vessels during the entire study period; R = −0.51, p < 0.0001. Our study shows that cardiopulmonary bypass‐induced acute microcirculatory perfusion disturbances persist in the first three postoperative days, and are associated with prolonged endothelial glycocalyx shedding. This suggests prolonged impairment and delayed recovery of both microcirculatory perfusion and function after on‐pump cardiac surgery.
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Affiliation(s)
- N A M Dekker
- Departments of Anaesthesiology, Physiology, and Cardiothoracic Surgery, Amsterdam UMC, VU University, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - D Veerhoek
- Departments of Anaesthesiology, Physiology, and Cardiothoracic Surgery, Amsterdam UMC, VU University, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - N J Koning
- Departments of Anaesthesiology, Physiology, and Cardiothoracic Surgery, Amsterdam UMC, VU University, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - A L I van Leeuwen
- Departments of Anaesthesiology, Physiology, and Cardiothoracic Surgery, Amsterdam UMC, VU University, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - P W G Elbers
- Department of Intensive Care Medicine, Research VUmc Intensive Care (REVIVE), Amsterdam UMC, VU University, Amsterdam Infection and Immunity Institute, Amsterdam, the Netherlands
| | - C E van den Brom
- Departments of Anaesthesiology, Physiology, and Cardiothoracic Surgery, Amsterdam UMC, VU University, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - A B A Vonk
- Department of Cardiothoracic Surgery, Amsterdam UMC, VU University, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - C Boer
- Department of Anaesthesiology, Amsterdam UMC, VU University, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
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LaRivière WB, Schmidt EP. The Pulmonary Endothelial Glycocalyx in ARDS: A Critical Role for Heparan Sulfate. CURRENT TOPICS IN MEMBRANES 2018; 82:33-52. [PMID: 30360782 DOI: 10.1016/bs.ctm.2018.08.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The endothelial glycocalyx is a glycosaminoglycan-enriched endovascular layer that, with the development of novel fixation and in vivo microscopy techniques, has been increasingly recognized as a major contributor to vascular homeostasis. Sepsis-associated degradation of the endothelial glycocalyx mediates the onset of the alveolar microvascular dysfunction characteristic of sepsis-induced lung injury (such as the Acute Respiratory Distress Syndrome, ARDS). Emerging evidence indicates that processes of glycocalyx reconstitution are necessary for endothelial repair and, as such, are promising therapeutic targets to accelerate lung injury recovery. This review discusses what has been learned about the homeostatic and pathophysiologic role of the pulmonary endothelial glycocalyx during lung health and injury, with the goal to identify promising new areas for future mechanistic investigation.
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Affiliation(s)
- Wells B LaRivière
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Aurora, CO, United States
| | - Eric P Schmidt
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Aurora, CO, United States.
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Machin DR, Bloom SI, Campbell RA, Phuong TTT, Gates PE, Lesniewski LA, Rondina MT, Donato AJ. Advanced age results in a diminished endothelial glycocalyx. Am J Physiol Heart Circ Physiol 2018; 315:H531-H539. [PMID: 29750566 DOI: 10.1152/ajpheart.00104.2018] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Age-related microvascular dysfunction is well characterized in rodents and humans, but little is known about the properties of the microvascular endothelial glycocalyx in advanced age. We examined the glycocalyx in microvessels of young and old male C57BL6 mice (young: 6.1 ± 0.1 mo vs. old: 24.6 ± 0.2 mo) using intravital microscopy and transmission electron microscopy and in human participants (young: 29 ± 1 yr vs. old: 60 ± 2 yr) using intravital microscopy. Glycocalyx thickness in mesenteric and skeletal muscle microvessels was 51-54% lower in old compared with young mice. We also observed 33% lower glycocalyx thickness in the sublingual microcirculation of humans in advanced age. The perfused boundary region, a marker of glycocalyx barrier function, was also obtained using an automated capture and analysis system. In advanced age, we observed a 10-22% greater perfused boundary region in mice and humans, indicating a more penetrable glycocalyx. Finally, using this automated analysis system, we examined perfused microvascular density and red blood cell (RBC) fraction. Perfused microvascular density is a marker of microvascular function that reflects the length of perfused microvessel segments in a given area; RBC fraction represents the heterogeneity in RBC presence between microvessel segments. Compared with young, the perfused microvascular density was 16-21% lower and RBC fraction was 5-14% lower in older mice and in older humans. These data provide novel evidence that, across mammalian species, a diminished glycocalyx is present in advanced age and is accompanied by markers of impaired microvascular perfusion. Age-related glycocalyx deterioration may be an important contributor to microvascular dysfunction in older adults and subsequent pathophysiology. NEW & NOTEWORTHY Advanced age is characterized by microvascular dysfunction that contributes to age-related cardiovascular diseases, but little is known about endothelial glycocalyx properties in advanced age. This study reveals, for the first time, lower glycocalyx thickness and barrier function that is accompanied by impaired microvascular perfusion in both mice and humans in advanced age.
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Affiliation(s)
- Daniel R Machin
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Salt Lake City, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Samuel I Bloom
- Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
| | - Robert A Campbell
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Molecular Medicine, University of Utah , Salt Lake City, Utah
| | - Tam T T Phuong
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Phillip E Gates
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Lisa A Lesniewski
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Salt Lake City, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
| | - Matthew T Rondina
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Salt Lake City, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Molecular Medicine, University of Utah , Salt Lake City, Utah
| | - Anthony J Donato
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Salt Lake City, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah.,Department of Biochemistry, University of Utah , Salt Lake City, Utah
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Yalcin O, Jani VP, Johnson PC, Cabrales P. Implications Enzymatic Degradation of the Endothelial Glycocalyx on the Microvascular Hemodynamics and the Arteriolar Red Cell Free Layer of the Rat Cremaster Muscle. Front Physiol 2018; 9:168. [PMID: 29615916 PMCID: PMC5864934 DOI: 10.3389/fphys.2018.00168] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 02/20/2018] [Indexed: 12/12/2022] Open
Abstract
The endothelial glycocalyx is a complex network of glycoproteins, proteoglycans, and glycosaminoglycans; it lines the vascular endothelial cells facing the lumen of blood vessels forming the endothelial glycocalyx layer (EGL). This study aims to investigate the microvascular hemodynamics implications of the EGL by quantifying changes in blood flow hydrodynamics post-enzymatic degradation of the glycocalyx layer. High-speed intravital microscopy videos of small arteries (around 35 μm) of the rat cremaster muscle were recorded at various time points after enzymatic degradation of the EGL. The thickness of the cell free layer (CFL), blood flow velocity profiles, and volumetric flow rates were quantified. Hydrodynamic effects of the presence of the EGL were observed in the differences between the thickness of CFL in microvessels with an intact EGL and glass tubes of similar diameters. Maximal changes in the thickness of CFL were observed 40 min post-enzymatic degradation of the EGL. Analysis of the frequency distribution of the thickness of CFL allows for estimation of the thickness of the endothelial surface layer (ESL), the plasma layer, and the glycocalyx. Peak flow, maximum velocity, and mean velocity were found to statistically increase by 24, 27, and 25%, respectively, after enzymatic degradation of the glycocalyx. The change in peak-to-peak maximum velocity and mean velocity were found to statistically increase by 39 and 32%, respectively, after 40 min post-enzymatic degradation of the EGL. The bluntness of blood flow velocity profiles was found to be reduced post-degradation of the EGL, as the exclusion volume occupied by the EGL increased the effective volume impermeable to RBCs in microvessels. This study presents the effects of the EGL on microvascular hemodynamics. Enzymatic degradation of the EGL resulted in a decrease in the thickness of CFL, an increase in blood velocity, blood flow, and decrease of the bluntness of the blood flow velocity profile in small arterioles. In summary, the EGL functions as a molecular sieve to solute transport and as a lubrication layer to protect the endothelium from red blood cell (RBC) motion near the vessel wall, determining wall shear stress.
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Affiliation(s)
- Ozlem Yalcin
- Koç University School of Medicine, Sariyer, Istanbul, Turkey.,Department of Bioengineering, University of California, San Diego, San Diego, La Jolla, CA, United States
| | - Vivek P Jani
- Department of Bioengineering, University of California, San Diego, San Diego, La Jolla, CA, United States
| | - Paul C Johnson
- Department of Bioengineering, University of California, San Diego, San Diego, La Jolla, CA, United States
| | - Pedro Cabrales
- Department of Bioengineering, University of California, San Diego, San Diego, La Jolla, CA, United States
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Impaired Tissue Oxygenation in Metabolic Syndrome Requires Increased Microvascular Perfusion Heterogeneity. J Cardiovasc Transl Res 2017; 10:69-81. [PMID: 28168652 DOI: 10.1007/s12265-017-9732-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 01/25/2017] [Indexed: 01/09/2023]
Abstract
Metabolic syndrome (MS) in obese Zucker rats (OZR) is associated with impaired skeletal muscle performance and blunted hyperemia. Studies suggest that reduced O2 diffusion capacity is required to explain compromised muscle performance and that heterogeneous microvascular perfusion distribution is critical. We modeled tissue oxygenation during muscle contraction in control and OZR skeletal muscle using physiologically realistic relationships. Using a network model of Krogh cylinders with increasing perfusion asymmetry and increased plasma skimming, we predict increased perfusion heterogeneity and decreased muscle oxygenation in OZR, with partial recovery following therapy. Notably, increasing O2 delivery had less impact on VO2 than equivalent decreases in O2 delivery, providing a mechanism for previous empirical work associating perfusion heterogeneity and impaired O2 extraction. We demonstrate that increased skeletal muscle perfusion asymmetry is a defining characteristic of MS and must be considered to effectively model and understand blood-tissue O2 exchange in this model of human disease.
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