Chondrogenesis of human mesenchymal stem cells in fibrin constructs evaluated in vitro and in nude mouse and rabbit defects models

In this study, hMSCs encapsulated in a fibrin hydrogel containing heparinized NPs loaded with TGF-β3 (100 ng/ml), or TGF-β3 (100 ng/ml) alone, were subjected to growth factor release and denaturation tests at one, two and four weeks in in vitro culture systems. Additionally, stem cell differentiation was assessed via RT-PCR, real-time quantitative PCR (qPCR), histology, and immunohistochemical assays. In the in vivo studies with nude mouse, when transplanted into nude mice, hMSCs embedded in fibrin hydrogels survived and proliferated more readily in those samples containing TGF-β3-loaded NPs, or TGF-β3 alone, compared to those containing only NPs or the fibrin hydrogel alone. Additionally, RT-PCR, real-time qPCR, histology, Western blotting, and immunohistochemistry analyses revealed that chondrocyte-specific extracellular matrix (ECM) genes and their proteins were expressed at high levels by hMSCs embedded in hydrogels containing TGF-β3-loaded NPs. Finally, the results observed in the rabbit animal model treated with hMSCs embedded in a fibrin hydrogel containing TGF-β3-loaded NPs were also evaluated by the RT-PCR, real-time qPCR, histology, Western blotting, and immunohistochemistry analyses. The in vitro and in vivo results indicated that transplanted hMSCs together with TGF-β3 may constitute a clinically efficient method for the regeneration of hyaline articular cartilage.