In situ thermal gelling polypeptide for chondrocytes 3D culture.

In the search for a cell-instructive or cell-interactive artificial extracellular matrix, synthetic hydrogels have been extensively investigated to apply three-dimensional (3D) cell culture and tissue engineering. Here, we are reporting a reverse thermal gelling l/dl-polyalanine block copolymer aqueous solution for chondrocyte 3D culture. The polymer aqueous solution undergoes sol-to-gel transition as the temperature increases, thus forming a 3D cell encapsulating scaffold in situ at 37 °C. In particular, the fraction of the β-sheet structure of the polyalanine dictated the population and thickness of fibrous nanostructure of the hydrogel, which in turn affected the proliferation and protein expression of the encapsulated chondrocytes. As an injectable tissue engineering system of chondrocytes, very promising results were confirmed for nude mice, using the current polypeptide aqueous solution. This paper not only provides important clues in designing an artificial extracellular matrix but also proves the significance of thermal gelling polypeptide as a minimally-invasive tissue engineering scaffold.