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Walker JC, Jorgensen AM, Sarkar A, Gent SP, Messerli MA. Anionic polymers amplify electrokinetic perfusion through extracellular matrices. Front Bioeng Biotechnol 2022; 10:983317. [PMID: 36225599 PMCID: PMC9548625 DOI: 10.3389/fbioe.2022.983317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/07/2022] [Indexed: 11/17/2022] Open
Abstract
Electrical stimulation (ES) promotes healing of chronic epidermal wounds and delays degeneration of articular cartilage. Despite electrotherapeutic treatment of these non-excitable tissues, the mechanisms by which ES promotes repair are unknown. We hypothesize that a beneficial role of ES is dependent on electrokinetic perfusion in the extracellular space and that it mimics the effects of interstitial flow. In vivo, the extracellular space contains mixtures of extracellular proteins and negatively charged glycosaminoglycans and proteoglycans surrounding cells. While these anionic macromolecules promote water retention and increase mechanical support under compression, in the presence of ES they should also enhance electro-osmotic flow (EOF) to a greater extent than proteins alone. To test this hypothesis, we compare EOF rates between artificial matrices of gelatin (denatured collagen) with matrices of gelatin mixed with anionic polymers to mimic endogenous charged macromolecules. We report that addition of anionic polymers amplifies EOF and that a matrix comprised of 0.5% polyacrylate and 1.5% gelatin generates EOF with similar rates to those reported in cartilage. The enhanced EOF reduces mortality of cells at lower applied voltage compared to gelatin matrices alone. We also use modeling to describe the range of thermal changes that occur during these electrokinetic experiments and during electrokinetic perfusion of soft tissues. We conclude that the negative charge density of native extracellular matrices promotes electrokinetic perfusion during electrical therapies in soft tissues and may promote survival of artificial tissues and organs prior to vascularization and during transplantation.
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Affiliation(s)
- Joseph C. Walker
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, United States
| | - Ashley M. Jorgensen
- Department of Mechanical Engineering, South Dakota State University, Brookings, SD, United States
| | - Anyesha Sarkar
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, United States
| | - Stephen P. Gent
- Department of Mechanical Engineering, South Dakota State University, Brookings, SD, United States
| | - Mark A. Messerli
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, United States
- *Correspondence: Mark A. Messerli,
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Su Y, Zhang X, Chen L, Li M, Gan Y, Wen F. AGE-RELATED RETENTIONAL AVASCULAR PIGMENT EPITHELIAL DETACHMENT VIEWED WITH INDOCYANINE GREEN ANGIOGRAPHY. Retina 2022; 42:1520-1528. [PMID: 35877973 PMCID: PMC9301995 DOI: 10.1097/iae.0000000000003487] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
PURPOSE Age-related scattered hypofluorescent spots on late-phase indocyanine green angiography (ASHS-LIA) might represent hydrophobic neutral lipid deposits in the Bruch membrane. This study aimed to report retentional avascular pigment epithelial detachment (PED) associated with ASHS-LIA. METHODS Patients aged ≥50 years who presented a single avascular serous PED without soft drusen or any other retinal or choroidal diseases were retrospectively included. Pigment epithelial detachment was classified as retentional, effusional, or mixed PED based on indocyanine green angiography. Multimodal images were qualitatively and quantitatively evaluated. RESULTS This study included 74 eyes of 57 patients. Retentional PED, effusional PED, and mixed PED accounted for 91.9%, 4.1%, and 4.1%, respectively. All PEDs were located in the macular region. Seventeen (29.8%) included patients had bilateral PEDs and all were retentional PEDs with a high level of bilateral consistency in the characteristics of PED and ASHS-LIA. All retentional PEDs were within the bounds of ASHS-LIA. The area of retentional PED increased with the ASHS-LIA grade ( P = 0.030). CONCLUSION Most age-related avascular serous PEDs are retentional PEDs. The location and area of retentional PEDs are consistent with the distribution of ASHS-LIA. These findings suggest that the hydrophobic neutral lipid deposits in the Bruch membrane might be involved in the pathogenesis and be a therapeutic target in age-related retentional avascular PED.
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Affiliation(s)
- Yongyue Su
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China; and
| | - Xiongze Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China; and
| | - Ling Chen
- The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Ophthalmology, and Chongqing Eye Institute, Chongqing, China.
| | - Miaoling Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China; and
| | - Yuhong Gan
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China; and
| | - Feng Wen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China; and
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Sarkar A, Messerli MA. Electrokinetic Perfusion Through Three-Dimensional Culture Reduces Cell Mortality. Tissue Eng Part A 2021; 27:1470-1479. [PMID: 33820474 DOI: 10.1089/ten.tea.2021.0008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cell proliferation and survival are dependent on mass transfer. In vivo, fluid flow promotes mass transfer through the vasculature and interstitial space, providing a continuous supply of nutrients and removal of cellular waste products. In the absence of sufficient flow, mass transfer is limited by diffusion and poses significant challenges to cell survival during tissue engineering, tissue transplantation, and treatment of degenerative diseases. Artificial perfusion may overcome these challenges. In this work, we compare the efficacy of pressure driven perfusion (PDP) with electrokinetic perfusion (EKP) toward reducing cell mortality in three-dimensional cultures of Matrigel extracellular matrix. We characterize electro-osmotic flow through Matrigel to identify conditions that generate similar interstitial flow rates to those induced by pressure. We also compare changes in cell mortality induced by continuous or pulsed EKP. We report that continuous EKP significantly reduced mortality throughout the perfusion channels more consistently than PDP at similar flow rates, and pulsed EKP decreased mortality just as effectively as continuous EKP. We conclude that EKP has significant advantages over PDP for promoting tissue survival before neovascularization and angiogenesis. Impact statement Interstitial flow helps promote mass transfer and cell survival in tissues and organs. This study generated interstitial flow using pressure driven perfusion (PDP) or electrokinetic perfusion (EKP) to promote cell viability in three-dimensional cultures. EKP through charged extracellular matrices possesses significant advantages over PDP and may promote cell survival during tissue engineering, transplantations, and treatment of degenerative diseases.
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Affiliation(s)
- Anyesha Sarkar
- Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota, USA
| | - Mark A Messerli
- Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota, USA
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Loss of Complement Factor H impairs antioxidant capacity and energy metabolism of human RPE cells. Sci Rep 2020; 10:10320. [PMID: 32587311 PMCID: PMC7316856 DOI: 10.1038/s41598-020-67292-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/19/2020] [Indexed: 12/28/2022] Open
Abstract
Polymorphisms in the Complement Factor H (CFH) gene, coding for the Factor H protein (FH), can increase the risk for age-related macular degeneration (AMD). AMD-associated CFH risk variants, Y402H in particular, impair FH function leading to complement overactivation. Whether this alone suffices to trigger AMD pathogenesis remains unclear. In AMD, retinal homeostasis is compromised due to the dysfunction of retinal pigment epithelium (RPE) cells. To investigate the impact of endogenous FH loss on RPE cell balance, we silenced CFH in human hTERT-RPE1 cells. FH reduction led to accumulation of C3, at both RNA and protein level and increased RPE vulnerability toward oxidative stress. Mild hydrogen-peroxide exposure in combination with CFH knock-down led to a reduction of glycolysis and mitochondrial respiration, paralleled by an increase in lipid peroxidation, which is a key aspect of AMD pathogenesis. In parallel, cell viability was decreased. The perturbations of energy metabolism were accompanied by transcriptional deregulation of several glucose metabolism genes as well as genes modulating mitochondrial stability. Our data suggest that endogenously produced FH contributes to transcriptional and metabolic homeostasis and protects RPE cells from oxidative stress, highlighting a novel role of FH in AMD pathogenesis.
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Chen L, Zhang X, Liu B, Mi L, Wen F. Age-related scattered hypofluorescent spots on late-phase indocyanine green angiography: the multimodal imaging and relevant factors. Clin Exp Ophthalmol 2018; 46:908-915. [PMID: 29675907 PMCID: PMC6282543 DOI: 10.1111/ceo.13306] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Accepted: 04/03/2018] [Indexed: 12/13/2022]
Abstract
Importance Fundus aging and its imaging features. Background To characterize the demographic and multimodal‐imaging features of age‐related scattered hypofluorescent spots on late‐phase indocyanine green angiography (ASHS‐LIA). Design A hospital‐based retrospective study. Participants Eight hundred and seventy‐five normal fundi fellow eyes from 875 patients underwent indocyanine green angiography (ICGA), fluorescence angiography (FA), autofluorescence (AF) and spectral‐domain optical coherence tomography (OCT). Methods Demographic information, medical records and multimodal imaging data were reviewed. Main Outcome Measures Diameter of ASHS‐LIA and its grade, subfoveal choroidal thickness (SFCT). Results ASHS‐LIA was identified in 233 patients (26.6%) aged 33 to 87 years (mean: 65.8 ± 8.4 years). Patients with ASHS‐LIA were significantly older and had a higher male proportion than those without ASHS‐LIA (both P < 0.001). The occurrence and grade of ASHS‐LIA increased with age (all P < 0.001). Age (OR = 1.093) and male gender (OR = 1.550) were the independent relevant factors of ASHS‐LIA (P < 0.001, and P = 0.002, respectively). The incidence of ASHS‐LIA in polypoidal choroidal vasculopathy (PCV) patients (53.2%) was the highest (all P < 0.001). ASHS‐LIA mainly located in macular region (diameter: 100–500 μm), and could be confluent. No corresponding abnormalities were detected via multimodal imaging, including FA, AF and OCT. The mean SFCT had no significant difference between eyes with and without ASHS‐LIA (P = 0.221). Conclusions and Relevance ASHS‐LIA was observed on late‐phase ICGA, mainly located in macular region. No corresponding abnormalities were detected by other multimodal imaging, including FA, AF and OCT. The occurrence and grade of ASHS‐LIA increased with age. Moreover, ASHS‐LIA might be not correlated with SFCT, but correlated with PCV.
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Affiliation(s)
- Ling Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xiongze Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Bing Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Lan Mi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Feng Wen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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Kuznetsova DS, Shirmanova MV, Dudenkova VV, Subochev PV, Turchin IV, Zagaynova EV, Lukyanov SA, Shakhov BE, Kamensky VA. Photobleaching and phototoxicity of KillerRed in tumor spheroids induced by continuous wave and pulsed laser illumination. JOURNAL OF BIOPHOTONICS 2015; 8:952-960. [PMID: 25648724 DOI: 10.1002/jbio.201400130] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 12/18/2014] [Accepted: 01/14/2015] [Indexed: 06/04/2023]
Abstract
The purpose of this study was to evaluate photobleaching of the genetically encoded photosensitizer KillerRed in tumor spheroids upon pulsed and continuous wave (CW) laser irradiation and to analyze the mechanisms of cancer cell death after the treatment. We observed the light-dose dependent mechanism of KillerRed photobleaching over a wide range of fluence rates. Loss of fluorescence was limited to 80% at light doses of 150 J/cm(2) and more. Based on the bleaching curves, six PDT regimes were applied for irradiation using CW and pulsed regimes at a power density of 160 mW/cm(2) and light doses of 140 J/cm(2) , 170 J/cm(2) and 200 J/cm(2). Irradiation of KillerRed-expressing spheroids in the pulsed mode (pulse duration 15 ns, pulse repetition rate 10 Hz) induced predominantly apoptotic cell death, while in the case of CW mode the cancer cells underwent necrosis. In general, these results improve our understanding of photobleaching mechanisms in GFP-like proteins and show the importance of appropriate selection of treatment mode for PDT with KillerRed. Representative fluorescence image of two KillerRed-expressing spheroids before and immediately after CW irradiation.
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Affiliation(s)
- Daria S Kuznetsova
- Nizhny Novgorod State Medical Academy, 603005, Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia.
- Lobachevsky State University of Nizhny Novgorod, 603950, Gagarin Ave., 23, Nizhny Novgorod, Russia.
| | - Marina V Shirmanova
- Nizhny Novgorod State Medical Academy, 603005, Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
- Lobachevsky State University of Nizhny Novgorod, 603950, Gagarin Ave., 23, Nizhny Novgorod, Russia
| | - Varvara V Dudenkova
- Nizhny Novgorod State Medical Academy, 603005, Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
- Lobachevsky State University of Nizhny Novgorod, 603950, Gagarin Ave., 23, Nizhny Novgorod, Russia
| | - Pavel V Subochev
- Institute of Applied Physics RAS, 603950, Ulyanov St., 46, Nizhny Novgorod, Russia
| | - Ilya V Turchin
- Institute of Applied Physics RAS, 603950, Ulyanov St., 46, Nizhny Novgorod, Russia
| | - Elena V Zagaynova
- Nizhny Novgorod State Medical Academy, 603005, Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
- Lobachevsky State University of Nizhny Novgorod, 603950, Gagarin Ave., 23, Nizhny Novgorod, Russia
| | - Sergey A Lukyanov
- Nizhny Novgorod State Medical Academy, 603005, Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, 117997, Miklukho-Maklaya St., 16/10, Moscow, Russia
- Pirogov Russian National Research Medical University, 117997, Ostrovitianova St. 1, Moscow, Russia
| | - Boris E Shakhov
- Nizhny Novgorod State Medical Academy, 603005, Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
| | - Vladislav A Kamensky
- Institute of Applied Physics RAS, 603950, Ulyanov St., 46, Nizhny Novgorod, Russia
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Cankova Z, Huang JD, Kruth HS, Johnson M. Passage of low-density lipoproteins through Bruch's membrane and choroid. Exp Eye Res 2011; 93:947-55. [PMID: 22063729 PMCID: PMC3242000 DOI: 10.1016/j.exer.2011.10.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 10/11/2011] [Accepted: 10/26/2011] [Indexed: 11/24/2022]
Abstract
Plasma lipoproteins are thought to transport cholesterol, vitamins and carotenoids to the retinal pigment epithelium (RPE) for ultimate use by the photoreceptors. However, to reach the RPE, these lipoprotein particles must cross Bruch's membrane. We examined the reflection coefficient of Bruch's membrane (BrM) to low-density lipoprotein (LDL). Bruch's membrane and choroid were removed from 47 bovine eyes. Specimens were placed in a Ussing chamber and perfused with phosphate-buffered saline (PBS) with (31 specimens) or without (16 specimens) fluorescent low-density lipoproteins (DiI-LDL). The hydraulic conductivity of the tissue was determined for both calf and cow eyes. In the perfusions with DiI-LDL, the fluorescence intensity emitted by DiI-LDL in the efflux was measured and the reflection coefficient of BrM/choroid preparations to DiI-LDL determined. Leakage tests were done to confirm tissue integrity. Several specimens were examined using scanning electron microscopy (SEM) to examine tissue integrity before and after perfusion. Leak testing confirmed that BrM was intact both before and after perfusion. The average hydraulic conductivity of BrM/choroid perfusion of calf eyes with PBS alone was 1.42 ± 0.55 × 10(-9) m/s/Pa (mean ± SD, n = 11). The average hydraulic conductivity of the cow eyes was 4.94 ± 1.48 × 10(-10) m/s/Pa (n = 5), nearly a 3-fold decrease with age. While the flow rate remained constant during the PBS perfusions, it decreased as a function of time during perfusion with DiI-LDLs. Our major finding was of fluorescence in the effluent collected in all perfusions with DiI-LDLs, demonstrating passage of LDL through the tissue. The average reflection coefficient of calf BrM/choroid preparations to DiI-LDL was 0.58 ± 0.25 (n = 23); a similar distribution of reflection coefficients was seen in tissue from cow eyes (0.51 ± 0.33, n = 8). Our data suggested that the DiI-LDL was modestly hindered and/or captured by the tissue. This might explain the progressive decrease of hydraulic conductivity with continued perfusion of DiI-LDL.
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Affiliation(s)
- Zdravka Cankova
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3107, USA
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Galli M, Fornasiere E, Cugnoni J, Oyen ML. Poroviscoelastic characterization of particle-reinforced gelatin gels using indentation and homogenization. J Mech Behav Biomed Mater 2011; 4:610-7. [DOI: 10.1016/j.jmbbm.2011.01.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 01/26/2011] [Accepted: 01/27/2011] [Indexed: 11/27/2022]
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Bjork JW, Tranquillo RT. Transmural flow bioreactor for vascular tissue engineering. Biotechnol Bioeng 2010; 104:1197-206. [PMID: 19603425 DOI: 10.1002/bit.22475] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nutrient transport limitation remains a fundamental issue for in vitro culture of engineered tissues. In this study, perfusion bioreactor configurations were investigated to provide uniform delivery of oxygen to media equivalents (MEs) being developed as the basis for tissue-engineered arteries. Bioreactor configurations were developed to evaluate oxygen delivery associated with complete transmural flow (through the wall of the ME), complete axial flow (through the lumen), and a combination of these flows. In addition, transport models of the different flow configurations were analyzed to determine the most uniform oxygen profile throughout the tissue, incorporating direct measurements of tissue hydraulic conductivity, cellular O(2) consumption kinetics, and cell density along with ME physical dimensions. Model results indicate that dissolved oxygen (DO) uniformity is improved when a combination of transmural and axial flow is implemented; however, detrimental effects could occur due to lumenal pressure exceeding the burst pressure or damaging interstitial shear stress imparted by excessive transmural flow rates or decreasing hydraulic conductivity due to ME compaction. The model was verified by comparing predicted with measured outlet DO concentrations. Based on these results, the combination of a controlled transmural flow coupled with axial flow presents an attractive means to increase the transport of nutrients to cells within the cultured tissue to improve growth (increased cell and extracellular matrix concentrations) as well as uniformity.
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Affiliation(s)
- Jason W Bjork
- Department of Biomedical Engineering, University of Minnesota 55455, USA
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Rutkowski JM, Markhus CE, Gyenge CC, Alitalo K, Wiig H, Swartz MA. Dermal collagen and lipid deposition correlate with tissue swelling and hydraulic conductivity in murine primary lymphedema. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 176:1122-9. [PMID: 20110415 DOI: 10.2353/ajpath.2010.090733] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Primary lymphedema is a congenital pathology of dysfunctional lymphatic drainage characterized by swelling of the limbs, thickening of the dermis, and fluid and lipid accumulation in the underlying tissue. Two mouse models of primary lymphedema, the Chy mouse and the K14-VEGFR-3-Ig mouse, both lack dermal lymphatic capillaries and exhibit a lymphedematous phenotype attributable to disrupted VEGFR-3 signaling. Here we show that the differences in edematous tissue composition between these two models correlated with drastic differences in hydraulic conductivity. The skin of Chy mice possessed significantly higher levels of collagen and fat, whereas K14-VEGFR-3-Ig mouse skin composition was relatively normal, as compared with their respective wild-type controls. Functionally, this resulted in a greatly increased dermal hydraulic conductivity in K14-VEGFR3-Ig, but not Chy, mice. Our data suggest that lymphedema associated with increased collagen and lipid accumulation counteracts an increased hydraulic conductivity associated with dermal swelling, which in turn further limits interstitial transport and swelling. Without lipid and collagen accumulation, hydraulic conductivity is increased and overall swelling is minimized. These opposing tissue responses to primary lymphedema imply that tissue remodeling--predominantly collagen and fat deposition--may dictate tissue swelling and govern interstitial transport in lymphedema.
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Affiliation(s)
- Joseph M Rutkowski
- Institute of Bioengineering, School of Life Sciences/LMBM/Station 15, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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Curcio CA, Johnson M, Huang JD, Rudolf M. Aging, age-related macular degeneration, and the response-to-retention of apolipoprotein B-containing lipoproteins. Prog Retin Eye Res 2009; 28:393-422. [PMID: 19698799 PMCID: PMC4319375 DOI: 10.1016/j.preteyeres.2009.08.001] [Citation(s) in RCA: 189] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The largest risk factor for age-related macular degeneration (ARMD) is advanced age. A prominent age-related change in the human retina is the accumulation of histochemically detectable neutral lipid in normal Bruch's membrane (BrM) throughout adulthood. This change has the potential to have a major impact on physiology of the retinal pigment epithelium (RPE). It occurs in the same compartment as drusen and basal linear deposit, the pathognomonic extracellular, lipid-containing lesions of ARMD. Here we present evidence from light microscopic histochemistry, ultrastructure, lipid profiling of tissues and isolated lipoproteins, and gene expression analysis that this deposition can be accounted for by esterified cholesterol-rich, apolipoprotein B-containing lipoprotein particles constitutively produced by the RPE. This work collectively allows ARMD lesion formation and its aftermath to be conceptualized as a response to the retention of a sub-endothelial apolipoprotein B lipoprotein, similar to a widely accepted model of atherosclerotic coronary artery disease (CAD) (Tabas et al., 2007). This approach provides a wide knowledge base and sophisticated clinical armamentarium that can be readily exploited for the development of new model systems and the future benefit of ARMD patients.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, AL 35294-0009, USA.
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Curcio CA, Johnson M, Huang JD, Rudolf M. Apolipoprotein B-containing lipoproteins in retinal aging and age-related macular degeneration. J Lipid Res 2009; 51:451-67. [PMID: 19797256 DOI: 10.1194/jlr.r002238] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The largest risk factor for age-related macular degeneration (ARMD) is advanced age. With aging, there is a striking accumulation of neutral lipids in Bruch's membrane (BrM) of normal eye that continues through adulthood. This accumulation has the potential to significantly impact the physiology of the retinal pigment epithelium (RPE). It also ultimately leads to the creation of a lipid wall at the same locations where drusen and basal linear deposit, the pathognomonic extracellular, lipid-containing lesions of ARMD, subsequently form. Here, we summarize evidence obtained from light microscopy, ultrastructural studies, lipid histochemistry, assay of isolated lipoproteins, and gene expression analysis. These studies suggest that lipid deposition in BrM is at least partially due to accumulation of esterified cholesterol-rich, apolipoprotein B-containing lipoprotein particles produced by the RPE. Furthermore, we suggest that the formation of ARMD lesions and their aftermath may be a pathological response to the retention of a sub-endothelial apolipoprotein B lipoprotein, similar to a widely accepted model of atherosclerotic coronary artery disease (Tabas, I., K. J. Williams, and J. Borén. 2007. Subendothelial lipoprotein retention as the initiating process in atherosclerosis: update and therapeutic implications. Circulation. 116:1832-1844). This view provides a conceptual basis for the development of novel treatments that may benefit ARMD patients in the future.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, AL, USA.
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Wang L, Li CM, Rudolf M, Belyaeva OV, Chung BH, Messinger JD, Kedishvili NY, Curcio CA. Lipoprotein particles of intraocular origin in human Bruch membrane: an unusual lipid profile. Invest Ophthalmol Vis Sci 2008; 50:870-7. [PMID: 18806290 DOI: 10.1167/iovs.08-2376] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Throughout adulthood, Bruch membrane (BrM) accumulates esterified cholesterol (EC) associated with abundant 60- to 80-nm-diameter lipoprotein-like particles (LLP), putative apolipoprotein B (apoB) lipoproteins secreted by the retinal pigment epithelium (RPE). In the present study, neutral lipid, phospholipids, and retinoid components of human BrM-LLP were assayed. METHODS Particles isolated from paired choroids of human donors were subjected to comprehensive lipid profiling (preparative liquid chromatography [LC] gas chromatography [GC]), thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), Western blot analysis, and negative stain electron microscopy. Results were compared to plasma lipoproteins isolated from normolipemic volunteers and to conditioned medium from RPE-J cells supplemented with palmitate to induce particle synthesis and secretion. RESULTS EC was the largest component (32.4+/-7.9 mol%) of BrM-LLP lipids. EC was 11.3-fold more abundant than triglyceride (TG), unlike large apoB lipoproteins in plasma. Of the fatty acids (FA) esterified to cholesterol, linoleate (18:2n6) was the most abundant (41.7+/-4.7 mol%). Retinyl ester (RE) was detectable at picomolar levels in BrM-LLP. Notably scarce in any BrM-LLP lipid class was the photoreceptor-abundant FA docosahexaenoate (DHA, 22:6n3). RPE-J cells synthesized apoB and numerous EC-rich spherical particles. CONCLUSIONS BrM-LLP composition resembles plasma LDL more than it does photoreceptors. An EC-rich core is possible for newly synthesized lipoproteins as well as those processed in plasma. Abundant EC could contribute to a transport barrier in aging and lesion formation in age-related maculopathy (ARM). Analysis of BrM-LLP composition has revealed new aspects of retinal cholesterol and retinoid homeostasis.
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Affiliation(s)
- Lan Wang
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0009, USA
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