Hepatogenesis of murine induced pluripotent stem cells in 3D micro-cavitary hydrogel system for liver regeneration.

The discovery of induced pluripotent stem cell (iPSC) technology has raised hopes in circumventing the current limitations in cell-based therapies where autologous stem cells could be generated from terminally differentiated somatic cells. Given the relatively short history of iPSC research, most of the studies are scientific exploratory in nature and hence have minimal practical usage. In this study, we aimed to combine existing knowledge on iPSC differentiation with three-dimensional (3D) scaffold platform so as to fabricate implantable constructs for liver regeneration. A micro-cavitary hydrogel (MCG) platform was employed as a continuous system for both colonies and/or EBs formation and differentiation. The advantage of MCG system is that it further enhances nutrient exchange and also permits greater living space for the encapsulated pluripotent stem cells to rapidly grow into colonies and/or EBs compared to typical non-MCG system. Murine iPSCs and embryonic stem cells (ESCs) were encapsulated respectively in alginate MCG system and after culturing for 10 days; colonies/EBs were formed spontaneously. Differentiation conditions were then introduced to direct the cells toward endodermal lineage and subsequently hepatic lineage and maturation. Up-regulation of endoderm markers and hepatic markers was observed in both iPSCs and ESCs suggesting that iPSC as effectively as the ESCs in MCG system. Urea and albumin production were significantly higher compared to monolayer culture, demonstrating the beneficial effects of MCG system. The results from this work provide foundation in understanding of iPSC differentiation in 3D engineered environment and aid in future biomedical research of iPSC technology.