Liver disease takes the lives of about two million people every year around the world. The prevalence of this family of diseases, however, outpaces the evolution of therapies. So, some scientists use human induced pluripotent stem cells (iPSCs) to produce hepatocyte-like cells (HLCs) that can be used as model systems for the development of new therapies for liver disease. Unfortunately, most methods produce very low numbers of HLCs. Margarida Serra, PhD, head of the stem and immune cells bioengineering lab at the Instituto de Biologia Experimental e Tecnológica (iBET) in Oeiras, Portugal, and her colleagues set out to solve that problem.
Using stirred-tank bioreactors and control of the dissolved oxygen (DO) concentration, Serra’s team searched for a method to produce more HLCs as 3D aggregates. To do this, these scientists compared HLC production with atmospheric oxygen concentration, which is about 21%, and the physiological level, which is about 4%. In particular, Serra and her colleagues studied the impact of these conditions on cell proliferation and differentiation of the hepatic progenitors. Plus, these scientists characterized the quality attributes of the HLCs with transcriptome analysis and biochemical assays.
Promising findings
This work revealed several promising findings. The results showed that 4% DO produced about three times more HLCs and nearly doubled the differentiation of the progenitor cells, compared with 21% DO. Plus, Serra’s team noted that the resulting HLCs “exhibited functional characteristics of hepatocytes: capacity to metabolize drugs, ability to synthesize hepatic metabolites, and inducible cytochrome P450 activity.”
Nonetheless, these scientists pushed this method even further. For one thing, they found similar results when starting with iPSCs from different donors. In addition, Serra and her colleagues tested the process with iPSCs created from donors with primary hyperoxaluria type 1 (PH1), which is a rare liver disease. The resulting HLCs “showed metabolic features of PH1 disease with higher secretion of oxalate compared with HLC generated from healthy individuals,” the scientists reported.
So, simply controlling the DO in bioreactors sets the stage for developing new treatments for liver disease. Nonetheless, Serra’s team pointed out that an HLC doesn’t completely possess the capabilities of a mature hepatocyte. Looking ahead, these scientists noted that “future experiments should focus on improving the maturation of the generated HLC to meet the needs of in vivo transplantation and in vitro model development.”
