The influence of bubble size on chondrogenic differentiation of adipose-derived stem cells in gelatin microbubble scaffolds.

In human bodies, cartilage tissue lacks the ability to heal when it encounters trauma or lesions. This inability of cartilage tissue to self-repair motivates all sorts of studies on autologous chondrocyte transplantation; however, the drawback of high chondrocyte concentration is hard to overcome due to the loss of differentiated chondrocyte phenotype during cell culture. The differentiation of stem cells into chondrocytes is a possible solution to provide a large number of differentiated chondrocytes. In this study, human adipose-derived stem cells (hASCs) have been chosen as a model for further differentiation into chondrocytes. Studies on the influence of porous biomaterials on cell behavior have been performed to determine the best conditions for stem cell differentiation. Among these conditions, bubble or pore size is a factor that is commonly discussed. In our study, we fabricated four gelatin microbubble scaffolds with different pore sizes, but uniform spherical shapes by microfluidic techniques. Then, we compared the influence of pore size on cell growth and differentiation. Previously, we have examined adipogenesis and osteogenesis of hASCs in this scaffold. In this study, we focused on the influence of pore size on chondrogenesis. According to the experimental results of immunofluorescence staining, GAG content, and qPCR, the largest pore size, which is 200 μm in diameter, shows the best chondrogenesis result.