Transplantation of poly(N-isopropylacrylamide-co-vinylimidazole) hydrogel constructs composed of rabbit chondrocytes and growth factor-loaded nanoparticles for neocartilage formation.

To evaluate their protein activity, heparinized nanoparticles (NPs) in which growth factors were loaded into a thermoreversible hydrogel [poly(N-isopropylacrylamide-co-vinylimidazole)]; p(NiPAAm-co-VI) have been investigated with regard to their activity in cell differentiation. Specifically, rabbit chondrocytes were embedded in composite hydrogels co-encapsulating NPs loaded with transforming growth factor beta-1 (TGF beta-1). The specific ECMs associated cartilage tissue component was determined via immunohistochemistry (IHC) and Alcian blue (GAG) staining. In the same period of transplantation, the DNA content was different for all formulations, thereby indicating that the dramatic increase in cell number for the TGF beta-1 loaded NP samples was accompanied by the maintenance of the cell phenotypes. These results suggested the growth factor-loaded heparinized NPs in a chondrocyte-embedded hydrogel as suitable model for the cartilage tissue regeneration.