Migration of dental pulp stem cells-derived chondrogenic cells in collagen hydrogels
The rapidly progressing field of regenerative medicine draws attention to various sources of adult stem cells that can be differentiated into many cellular lineages and tissues. Human dental pulp stem cells (DPSCs) are found within teeth and can be harvested during extractions of teeth. These highly proliferative mesenchymal stem cells were shown to be differentiated into various cellular lineages. DPSCs encapsulated in type I and type II collagen hydrogels can be transplanted into degenerated nucleus pulposus (NP) to repair damaged tissue. The motility of transplanted cells is critical because the cells need to migrate away from the hydrogels containing the cells of high density and disperse into the NP tissue after implantation. In this research, DPSCs were differentiated into chondrogenic and neurogenic cells. Migration properties of DPSCs as well as DPSCs-derived chondrogenic cells were investigated in two- and three-dimensional environments. Collagen type I and type II were used to generate hydrogels with or without crosslinking by 4S-Star-PEG. Time lapse imaging was utilized to record and analyze the cell migration in the hydrogels. This study showed that type I and II collagen hydrogels can support growth and proliferation of DPSCs. The study also demonstrated that DPSCs migrated well in both the 2D and 3D environments and the cell migration speed was not significantly different in either type I collagen or type II collagen hydrogels. The migration speed of DPSC-derived chondrogenic cells was higher in type I collagen hydrogel compared to type II collagen hydrogel. Crosslinking of collagen hydrogels does not reduce cell migration velocity of undifferentiated DPSCs, but causes a significant decline of migration velocity of DPSC-derived chondrogenic cells. This study indicated that after implantation of collagen hydrogels encapsulating DPSCs or DPSC-derived chondrogenic cells, the cells can potentially migrate from the hydrogels and migrate into the NP tissue.