Fabrication of liver microtissue with liver decellularized extracellular matrix (dECM) bioink by digital light processing (DLP) bioprinting.

As one of the most effective treatments of end-stage liver disease, liver transplantation still suffers from a shortage of donor organs or a low degree of engraftment. Thus, alternatives to liver transplantation, such as liver support systems, have to be extensively explored. In this study, a novel liver microtissue with an inner gear-like structure, which achieved a larger body surface area, was designed and manufactured to improve hepatic functional restoration. The liver-specific bioinks were developed by combining photocurable methacrylated gelatin (GelMA) with liver decellularized extracellular matrix (dECM), and human-induced hepatocytes (hiHep cells) were encapsulated to form cell-laden bioinks. The mechanical properties, swelling, and cytocompatibility of GelMA/dECM bioinks were carefully characterized before 3D printing. Then, the digital light process (DLP)-based bioprinting was used to fabricate the liver microtissue, and liver dECM was found to improve both the printability and cell viability of GelMA bioinks. hiHep cells were also found to spread farther and have better hepatocyte-specific functions (albumin secretion and urea) in the liver microtissue when liver dECM was added to the GelMA bioinks. Our results provide a promising liver dECM-based cell-laden bioink for liver microtissue fabrication, which would be a potential liver tissue engineering product to help restore hepatic functions.