Success of adipose tissue engineering for soft tissue repair has been limited by insufficient adipogenic differentiation, an unfavorable host response, and insufficient vascularization. In this study, we examined how scaffold-free spheroid and fibrin-based environments impact these parameters in human adipose-derived stromal cell (ASC)-based adipose constructs. ASCs were differentiated in spheroids or fibrin-based constructs. After 7 days, conditioned medium was collected and spheroids/fibrin-based constructs were either harvested or implanted subcutaneously in athymic mice. Following 7 days of implantation, the number of blood vessels in fibrin-based constructs was significantly higher than in spheroids (93 ± 45 vs. 23 ± 11 vessels/mm2) and the inflammatory response to fibrin-based constructs was less severe. The reasons for these results were investigated further in vitro. We found that ASCs in fibrin-based constructs secreted significantly higher levels of the angiogenic factors VEGF and HGF and lower levels of the inflammatory cytokine IL-8. Furthermore, ASCs in fibrin-based constructs secreted significantly higher levels of leptin and showed a 2.5-fold upregulation of the adipogenic transcription factor PPARG and a fourfold to fivefold upregulation of the adipocyte-specific markers FABP4, perilipin, and leptin. These results indicate that fibrin-based ASC constructs are potentially more suitable for ASC-based adipose tissue reconstruction than scaffold-free spheroids.

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Cell Transplantation: the regenerative medicine journal
Erasmus MC: University Medical Center Rotterdam

Verseijden, F, Posthumus-van Sluijs, S.J, van Neck, J.W, Hofer, S.O.P, Hovius, S.E.R, & van Osch, G.J.V.M. (2012). Comparing scaffold-free and fibrin-based adipose-derived stromal cell constructs for adipose tissue engineering: An in vitro and in vivo study. Cell Transplantation: the regenerative medicine journal, 21(10), 2283–2297. doi:10.3727/096368912X653129