Gelatin sponge patch grafting of microcryogel-based three-dimensional mesenchymal stem cells to alleviate acute liver failure.

The clinical application of human umbilical cord mesenchymal stem cells (hUCMSCs) in the treatment of liver failure faces challenges due to cell quality, short engraftment time, and limited efficacy. Here, gelatin microcryogel (GM) microcarriers with pore sizes ranging from 15 to 36 μm were tuned from mixed gelatin and glutaraldehyde to develop a 3D culture system of hUCMSCs with improved therapeutic effects. Bulk RNA sequencing and in vitro assays showed that 3D-hUCMSCs exhibited significant improvement in signaling pathways related to paracrine secretion and anti-inflammation. These 3D-hUCMSCs superior compared to 2D-hUCMSCs not only in terms of paracrine secretion, protection from oxidation, and resistance to mechanical force damage, but also had better liver function improvement effect than 2D-hUCMSCs when they were transplanted as single cells into liver injury mice. Furthermore, a gelatin sponge patch grafting (GSPG) strategy was developed to enable the direct engraftment of 3D-hUCMSCs within the GM microcarriers. The results showed that overall engraftment in the host liver was significantly improved, and the life span of transplanted hosts was extended. Our study provided a practical strategy to achieve high engraftment and long retraining time of 3D-hUCMSCs in rescuing acute liver failure with gelatin matrixes.