| 1. |
- Moelzer, Christine, et al.
(författare)
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Activation of dendritic cells by crosslinked collagen hydrogels (artificial corneas) varies with their composition
- 2019
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : WILEY. - 1932-6254 .- 1932-7005. ; 13:9, s. 1528-1543
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Tidskriftsartikel (refereegranskat)abstract
- Activated T cells are known to promote fibrosis, a major complication limiting the range of polymeric hydrogels as artificial corneal implants. As T cells are activated by dendritic cells (DC), minimally activating hydrogels would be optimal. In this study, we evaluated the ability of a series of engineered (manufactured/fabricated) and natural collagen matrices to either activate DC or conversely induce DC apoptosis in vitro. Bone marrow DC were cultured on a series of singly and doubly crosslinked hydrogels (made from recombinant human collagen III [RHCIII] or collagen mimetic peptide [CMP]) or on natural collagen-containing matrices, Matrigel(TM) and de-cellularised mouse corneal stroma. DC surface expression of major histocompatibility complex Class II and CD86 as well as apoptosis markers were examined. Natural matrices induced low levels of DC activation and maintained a "tolerogenic" phenotype. The same applied to singly crosslinked CMP-PEG gels. RHCIII gels singly crosslinked using either N-(3-dimethylaminopropyl)-N -ethylcarbodiimide with the coinitiator N-hydroxy succinimide (EDC-NHS) or N-cyclohexyl-N-(2-morpholinoethyl)carbodiimide metho-p-toulenesulfonate with NHS (CMC-NHS) induced varying levels of DC activation. In contrast, however, RHCIII hydrogels incorporating an additional polymeric network of 2-methacryloyloxyethyl phosphorylcholine did not activate DC but instead induced DC apoptosis, a phenomenon observed in natural matrices. This correlated with increased DC expression of leukocyte-associated immunoglobulin-like receptor-1. Despite low immunogenic potential, viable tolerogenic DC migrated into and through both natural and manufactured RHCIII gels. These data show that the immunogenic potential of RHCIII gels varies with the nature and composition of the gel. Preclinical evaluation of hydrogel immunogenic/fibrogenic potential is recommended.
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| 2. |
- Molzer, Christine, et al.
(författare)
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TGF-beta 1-activated type 2 dendritic cells promote wound healing and induce fibroblasts to express tenascin c following corneal full-thickness hydrogel transplantation
- 2019
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : WILEY. - 1932-6254 .- 1932-7005. ; 13:9, s. 1507-1517
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Tidskriftsartikel (refereegranskat)abstract
- We showed previously that 1-ethyl-3-(3-dimethylamino-propyl)-carbodiimide hydrochloride (EDC) cross-linked recombinant human collagen III hydrogels promoted stable regeneration of the human cornea (continued nerve and stromal cell repopulation) for over 4 years. However, as EDC cross linking kinetics were difficult to control, we additionally tested a sterically bulky carbodiimide. Here, we compared the effects of two carbodiimide cross linkers-bulky, aromatic N-cyclohexyl-N0-(2-morpholinoethyl)-carbodiimide (CMC), and nonbulky EDC-in a mouse corneal graft model. Murine corneas undergoing full-thickness implantation with these gels became opaque due to dense retro-corneal membranes (RCM). Corneal epithelial cytokeratin 12 and alpha smooth muscle actin indicative of functional tissue regeneration and wound contraction were observed in RCM surrounding both hydrogel types. However, quantitatively different levels of infiltrating CD11c(+) dendritic cells (DC) were found, suggesting a hydrogel-specific innate immune response. More DC infiltrated the stroma surrounding EDC-N-hydroxysuccinimide (NHS) hydrogels concurrently with higher fibrosis-associated tenascin c expression. The opposite was true for CMC-NHS gels that had previously been shown to be more tolerising to DC. In vitro studies showed that DC cultured with transforming growth factor beta 1 (TGF-beta 1) induced fibroblasts to secrete more tenascin c than those cultured with lipopolysaccharide and this effect was blocked by TGF-beta 1 neutralisation. Furthermore, tenascin c staining was found in 40- to 50 mu m long membrane nanotubes formed in fibroblast/DC cocultures. We suggest that TGF-beta 1 alternatively activated (tolerising) DC regulate fibroblast-mediated tenascin c secretion, possibly via local production of TGF-beta 1 in early wound contraction, and that this is indirectly modulated by different hydrogel chemistries.
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| 3. |
- Rajendran, Vijayalakshmi, et al.
(författare)
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Mesenchymal stem cell therapy for retro-corneal membrane - A clinical challenge in full-thickness transplantation of biosynthetic corneal equivalents
- 2017
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Ingår i: Acta Biomaterialia. - : ELSEVIER SCI LTD. - 1742-7061 .- 1878-7568. ; 64, s. 346-356
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Tidskriftsartikel (refereegranskat)abstract
- Artificial corneas (keratoprostheses) and biosynthetic collagen-based corneal equivalents are surgical implants designed to ease the global burden of corneal blindness. However, keratoprostheses in many cases fail due to development of fibrous retro-corneal membranes (RCM). Fibrous membranes which develop in the anterior chamber after prosthesis implantation do so on a matrix of fibrin. This study investigated fibrin deposition and RCM formation after full-thickness collagen-based hydrogel implants and compared them with syngeneic and allogeneic corneal grafts in mice. Fibrin cleared from the anterior chamber within 14 days in both allo- and syn-grafts but, persisted in hydrogel implants and developed into dense retro-corneal membrane (RCM) which were heavily infiltrated by activated myofibroblasts. In contrast, the number of CD11 b(+) macrophages infiltrating the initial deposition of fibrin in the anterior chamber (AC) after hydrogel implantation was markedly reduced compared to syn- and allo-grafts. Inoculation of mesenchymal stem cells prior to collagen gel implant promoted clearance of gel associated fibrin from the anterior chamber. We propose that a failure of macrophage-mediated clearance of fibrin may be the cause of RCM formation after collagen-based hydrogel implants and that mesenchymal stem cell therapy promotes clearance of fibrin and prevents RCM formation. Statement of Significance The manuscript addresses the potential value of bone marrow-derived mesenchymal stem cell therapy for retro-corneal membrane (RCM) formation in full-thickness transplantation of biosynthetic corneal equivalents. This work reports the pathophysiological changes in the anterior chamber of the mouse eye following full-thickness recombinant human cross-linked collagen-based hydrogel implants in which persistent fibrin promotes the development of dense RCM. Furthermore, pre-treatment with mesenchymal stem cells reduces RCM formation and enhances corneal transparency. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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