Rapid sol-gel reversible thermosensitive collagen for 3D cell culture

Collagen is usually dissolved in the acid solution and neutralized to mix cells for three-dimensional (3D) cell culture. During this process, the acid collagen solution must be precisely adjusted into the pH neutral on the ice platform; after mixing cells, the collagen/cells solution need more than 30 min to gelate at 37 ℃; moreover, the cells embedded in the collagen/cells hydrogel have to be harvested through collagen enzymolysis with enzyme such as collagenase if necessary. Herein, we developed the rapid sol-gel reversible thermosensitive collagen (RRTC) for 3D cell culture. The pH neutral collagen solution could directly mix cells at room temperature; the RRTC/cells solution could gelate in 60 s or less at 37 ℃; especially, the cells embedded in the RRTC/cells hydrogel could be harvested through hydrogel phase transformation from gel to sol. The L929 cells, human umbilical vein endothelial cells (HUVEC), Sp2/0 cells, murine aortic vascular smooth muscle cells (MOVAS), rat intestinal epithelial cells (IEC-6) and human chondrocytes were 3D cultured via the RRTC and grew well. The cells could proliferate by about 10 times in 14 days and preserve the high cell viability of over 90 %. The experiments of mouse skin regeneration demonstrated the RRTC solution could in situ quickly gelate on the skin wound for the skin regeneration. Therefore, this novel collagen biomaterial could be used as an efficient tool to fabricate 3D cell culture and have more clinical applications.