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O'Grady BJ, Balotin KM, Bosworth AM, McClatchey PM, Weinstein RM, Gupta M, Poole KS, Bellan LM, Lippmann ES. Development of an N-Cadherin Biofunctionalized Hydrogel to Support the Formation of Synaptically Connected Neural Networks. ACS Biomater Sci Eng 2020; 6:5811-5822. [PMID: 33320550 PMCID: PMC7791574 DOI: 10.1021/acsbiomaterials.0c00885] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In vitro models of the human central nervous system (CNS), particularly those derived from induced pluripotent stem cells (iPSCs), are becoming increasingly recognized as useful complements to animal models for studying neurological diseases and developing therapeutic strategies. However, many current three-dimensional (3D) CNS models suffer from deficits that limit their research utility. In this work, we focused on improving the interactions between the extracellular matrix (ECM) and iPSC-derived neurons to support model development. The most common ECMs used to fabricate 3D CNS models often lack the necessary bioinstructive cues to drive iPSC-derived neurons to a mature and synaptically connected state. These ECMs are also typically difficult to pattern into complex structures due to their mechanical properties. To address these issues, we functionalized gelatin methacrylate (GelMA) with an N-cadherin (Cad) extracellular peptide epitope to create a biomaterial termed GelMA-Cad. After photopolymerization, GelMA-Cad forms soft hydrogels (on the order of 2 kPa) that can maintain patterned architectures. The N-cadherin functionality promotes survival and maturation of single-cell suspensions of iPSC-derived glutamatergic neurons into synaptically connected networks as determined by viral tracing and electrophysiology. Immunostaining reveals a pronounced increase in presynaptic and postsynaptic marker expression in GelMA-Cad relative to Matrigel, as well as extensive colocalization of these markers, thus highlighting the biological activity of the N-cadherin peptide. Overall, given its ability to enhance iPSC-derived neuron maturity and connectivity, GelMA-Cad should be broadly useful for in vitro studies of neural circuitry in health and disease.
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Affiliation(s)
- Brian J O'Grady
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
- Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Kylie M Balotin
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Allison M Bosworth
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - P Mason McClatchey
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Robert M Weinstein
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Mukesh Gupta
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Kara S Poole
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Leon M Bellan
- Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Ethan S Lippmann
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
- Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
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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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McClatchey PM, Williams IM, Xu Z, Mignemi NA, Hughey CC, McGuinness OP, Beckman JA, Wasserman DH. Perfusion controls muscle glucose uptake by altering the rate of glucose dispersion in vivo. Am J Physiol Endocrinol Metab 2019; 317:E1022-E1036. [PMID: 31526289 PMCID: PMC6957378 DOI: 10.1152/ajpendo.00260.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
These studies test, using intravital microscopy (IVM), the hypotheses that perfusion effects on insulin-stimulated muscle glucose uptake (MGU) are 1) capillary recruitment independent and 2) mediated through the dispersion of glucose rather than insulin. For experiment 1, capillary perfusion was visualized before and after intravenous insulin. No capillary recruitment was observed. For experiment 2, mice were treated with vasoactive compounds (sodium nitroprusside, hyaluronidase, and lipopolysaccharide), and dispersion of fluorophores approximating insulin size (10-kDa dextran) and glucose (2-NBDG) was measured using IVM. Subsequently, insulin and 2[14C]deoxyglucose were injected and muscle phospho-2[14C]deoxyglucose (2[C14]DG) accumulation was used as an index of MGU. Flow velocity and 2-NBDG dispersion, but not perfused surface area or 10-kDa dextran dispersion, predicted phospho-2[14C]DG accumulation. For experiment 3, microspheres of the same size and number as are used for contrast-enhanced ultrasound (CEU) studies of capillary recruitment were visualized using IVM. Due to their low concentration, microspheres were present in only a small fraction of blood-perfused capillaries. Microsphere-perfused blood volume correlated to flow velocity. These findings suggest that 1) flow velocity rather than capillary recruitment controls microvascular contributions to MGU, 2) glucose dispersion is more predictive of MGU than dispersion of insulin-sized molecules, and 3) CEU measures regional flow velocity rather than capillary recruitment.
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Affiliation(s)
- P Mason McClatchey
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Ian M Williams
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Zhengang Xu
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Nicholas A Mignemi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Curtis C Hughey
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Owen P McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, Tennessee
| | | | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, Tennessee
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Kolka CM. The vascular endothelium plays a role in insulin action. Clin Exp Pharmacol Physiol 2019; 47:168-175. [PMID: 31479553 DOI: 10.1111/1440-1681.13171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/23/2019] [Accepted: 08/27/2019] [Indexed: 12/30/2022]
Abstract
The endocrine system relies on the vasculature for delivery of hormones throughout the body, and the capillary microvasculature is the site where the hormones cross from the blood into the target tissue. Once considered an inert wall, various studies have now highlighted the functions of the capillary endothelium to regulate transport and therefore affect or maintain the interstitial environment. The role of the capillary may be clear in areas where there is a continuous endothelium, yet there also appears to be a role of endothelial cells in tissues with a sinusoidal structure. Here we focused on the most common endocrine disorder, diabetes, and several of the target organs associated with the disease, including skeletal muscle, liver and pancreas. However, it is important to note that the ability of hormones to cross the endothelium to reach their target tissue is a component of all endocrine functions. It is also a consideration in organs throughout the body and may have greater impact for larger hormones with target tissues containing a continuous endothelium. We noted that the blood levels do not always equal interstitial levels, which is what the cells are exposed to, and discussed how this may change in diseases such as obesity and insulin resistance. The capillary endothelium is, therefore, an essential and understudied aspect of endocrinology and metabolism that can be altered in disease, which may be an appropriate target for treatment.
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Affiliation(s)
- Cathryn M Kolka
- Department of Biomedical Science, Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
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McClatchey PM, McClain ES, Williams IM, Malabanan CM, James FD, Lord PC, Gregory JM, Cliffel DE, Wasserman DH. Fibrotic Encapsulation Is the Dominant Source of Continuous Glucose Monitor Delays. Diabetes 2019; 68:1892-1901. [PMID: 31399432 PMCID: PMC6754243 DOI: 10.2337/db19-0229] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 07/17/2019] [Indexed: 01/06/2023]
Abstract
Continuous glucose monitor (CGM) readings are delayed relative to blood glucose, and this delay is usually attributed to the latency of interstitial glucose levels. However, CGM-independent data suggest rapid equilibration of interstitial glucose. This study sought to determine the loci of CGM delays. Electrical current was measured directly from CGM electrodes to define sensor kinetics in the absence of smoothing algorithms. CGMs were implanted in mice, and sensor versus blood glucose responses were measured after an intravenous glucose challenge. Dispersion of a fluorescent glucose analog (2-NBDG) into the CGM microenvironment was observed in vivo using intravital microscopy. Tissue deposited on the sensor and nonimplanted subcutaneous adipose tissue was then collected for histological analysis. The time to half-maximum CGM response in vitro was 35 ± 2 s. In vivo, CGMs took 24 ± 7 min to reach maximum current versus 2 ± 1 min to maximum blood glucose (P = 0.0017). 2-NBDG took 21 ± 7 min to reach maximum fluorescence at the sensor versus 6 ± 6 min in adipose tissue (P = 0.0011). Collagen content was closely correlated with 2-NBDG latency (R = 0.96, P = 0.0004). Diffusion of glucose into the tissue deposited on a CGM is substantially delayed relative to interstitial fluid. A CGM that resists fibrous encapsulation would better approximate real-time deviations in blood glucose.
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Affiliation(s)
- P Mason McClatchey
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Ethan S McClain
- Department of Chemistry, Vanderbilt University, Nashville, TN
| | - Ian M Williams
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Carlo M Malabanan
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN
| | - Freyja D James
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | | | - Justin M Gregory
- Ian M. Burr Division of Pediatric Endocrinology and Diabetes, Vanderbilt University School of Medicine, Nashville, TN
| | - David E Cliffel
- Department of Chemistry, Vanderbilt University, Nashville, TN
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN
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Mignemi NA, McClatchey PM, Kilchrist KV, Williams IM, Millis BA, Syring KE, Duvall CL, Wasserman DH, McGuinness OP. Rapid changes in the microvascular circulation of skeletal muscle impair insulin delivery during sepsis. Am J Physiol Endocrinol Metab 2019; 316:E1012-E1023. [PMID: 30860883 PMCID: PMC6620574 DOI: 10.1152/ajpendo.00501.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 02/21/2019] [Accepted: 03/07/2019] [Indexed: 01/07/2023]
Abstract
Sepsis costs the healthcare system $23 billion annually and has a mortality rate between 10 and 40%. An early indication of sepsis is the onset of hyperglycemia, which is the result of sepsis-induced insulin resistance in skeletal muscle. Previous investigations have focused on events in the myocyte (e.g., insulin signaling and glucose transport and subsequent metabolism) as the causes for this insulin-resistant state. However, the delivery of insulin to the skeletal muscle is also an important determinant of insulin action. Skeletal muscle microvascular blood flow, which delivers the insulin to the muscle, is known to be decreased during sepsis. Here we test whether the reduced capillary blood flow to skeletal muscle belies the sepsis-induced insulin resistance by reducing insulin delivery to the myocyte. We hypothesize that decreased capillary flow and consequent decrease in insulin delivery is an early event that precedes gross cardiovascular alterations seen with sepsis. This hypothesis was examined in mice treated with either lipopolysaccharide (LPS) or polymicrobial sepsis followed by intravital microscopy of the skeletal muscle microcirculation. We calculated insulin delivery to the myocyte using two independent methods and found that LPS and sepsis rapidly reduce insulin delivery to the skeletal muscle by ~50%; this was driven by decreases in capillary flow velocity and the number of perfused capillaries. Furthermore, the changes in skeletal muscle microcirculation occur before changes in both cardiac output and arterial blood pressure. These data suggest that a rapid reduction in skeletal muscle insulin delivery contributes to the induction of insulin resistance during sepsis.
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Affiliation(s)
- Nicholas A Mignemi
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - P Mason McClatchey
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Kameron V Kilchrist
- Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee
| | - Ian M Williams
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Bryan A Millis
- Department of Cell and Developmental Biology, Vanderbilt University , Nashville, Tennessee
- Vanderbilt Biophotonics Center, Vanderbilt University , Nashville, Tennessee
| | - Kristen E Syring
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Craig L Duvall
- Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
- Vanderbilt Mouse Metabolic Phenotyping Center , Nashville, Tennessee
| | - Owen P McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
- Vanderbilt Mouse Metabolic Phenotyping Center , Nashville, Tennessee
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