title: Interplay between local versus soluble transforming growth factor-beta and fibrin scaffolds: role of cells and impact on human mesenchymal stem cell chondrogenesis.
abstract: Structural extracellular matrix molecules gain increasing attention as scaffolds for cartilage tissue engineering owing to their natural role as a growth factor repository. We recently observed that a collagen-type I/III (Col-I/III) matrix, human recombinant transforming growth factor-beta (TGF-β) protein, and fibrin hydrogel (FG) combined to a biphasic construct provided sufficient long-term TGF-β support to drive in vitro chondrogenesis of human mesenchymal stem cells (hMSC). Here we ask whether FG and Col-I/III can both retain TGF-β, describe the influence of cell seeding on TGF-β release, and compare the molecular path of hMSC chondrogenic differentiation under soluble versus local TGF-β supply. Release of growth factor from scaffolds augmented with increasing amounts of TGF-β was analyzed over 7 days and chondrogenesis was assessed over 42 days. Low TGF-β release rates from Col-I/III as opposed to higher release from FG indicated that both molecules retained TGF-β, with Col-I/III being the superior storage component. Cell seeding enhanced TGF-β retention in FG by about threefold and almost stopped release beyond 24 h. TGF-β remained bioactive and supported MSC chondrogenesis without impairing the amount of proteoglycan and collagen-type II deposition per cell and per construct compared to standard scaffold-free MSC pellets supplied with soluble TGF-β. Local TGF-β, however, mediated lower cell content, less collagen-type X relative to collagen-type II deposition and no matrix metalloproteinase-13 up-regulation. In conclusion, cells quickly halted release of local TGF-β from FG, turning FG and Col-I/III into attractive TGF-β repositories capable to drive full hMSC chondrogenesis, but via a modulated differentiation pathway. Since only part of the changes was reproduced by transient soluble TGF-β supply, release kinetics alone could not explain the molecular differences, suggesting that local TGF-β acts distinct from its soluble counterpart.
authors.affiliation: Research Center for Experimental Orthopaedics, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: Solvig
authors.initials: S
authors.lastname: Diederichs
authors.forename: Kerstin
authors.initials: K
authors.lastname: Baral
authors.forename: Michael
authors.initials: M
authors.lastname: Tanner
authors.forename: Wiltrud
authors.initials: W
authors.lastname: Richter
mesh_terms: D001672:Biocompatible Materials / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D020219:Chondrogenesis / Q000187:drug effects*; D024043:Collagen Type II / Q000378:metabolism; D005337:Fibrin / Q000494:pharmacology*; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000494:pharmacology; D006984:Hypertrophy; D007700:Kinetics; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects*; D008875:Middle Aged; D011509:Proteoglycans / Q000378:metabolism; D012995:Solubility / Q000187:drug effects; D054457:Tissue Scaffolds / Q000737:chemistry*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D001672:Biocompatible Materials; D024043:Collagen Type II; D011509:Proteoglycans; D016212:Transforming Growth Factor beta; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D005337:Fibrin