Development of hepatocyte-embedded hydrogel-filled macroporous scaffold cultures using transglutaminase

We aimed to develop cell-embedded gel-filled macroporous scaffold (CGS) culture technology as a fundamental technology for the construction of large-scale tissue-like structures, which will be indispensable for practical liver tissue engineering. Tissue transglutaminase (tTGase) from guinea pig liver showed no cytotoxicity toward primary hepatocytes, and hepatocyte-embedded gelatin gel cultures could be realized. The albumin production activities in tTGase-mediated hepatocyte-embedded gelatin gel cultures were similar to those in collagen gel cultures, representing an established hepatocyte culture method for the expression of liver-specific functions. Therefore, it was expected that a hepatocyte-embedded gelatin gel culture system enabling high liver-specific function expression could be created. The CGS culture system was created by incubating a suspension of hepatocytes and tTGase-containing gelatin-filled hydrophilic-treated scaffolds at 37 °C. The albumin production activities in CGS with poly(l-lactic acid) macroporous scaffold (porosity = 68.4%) were inferior to those in tTGase-gelatin gel cultures because of a diffusion problem. However, the activities were similar between CGS with macroporous polyurethane foam (porosity = 98.8%) and tTGase-gelatin gel cultures, even under stationary conditions. On the other hand, further functional improvements of hepatocytes were achieved in HGF- or HGF/heparin-containing gel cultures. Based on these results, tTGase-mediated CGS cultures are expected to become a fundamental technology for the creation of engineered liver tissues.