Functional hit 1 (FH1)-based rapid and efficient generation of functional hepatocytes from human mesenchymal stem cells: a novel strategy for hepatic differentiation

Stem Cell-Based Strategies: The Future Direction of Bioartificial Liver Development

Acute liver failure (ALF) results from severe liver damage or end-stage liver disease. It is extremely fatal and causes serious health and economic burdens worldwide. Once ALF occurs, liver transplantation (LT) is the only definitive and recommended treatment; however, LT is limited by the scarcity of liver grafts. Consequently, the clinical use of bioartificial liver (BAL) has been proposed as a treatment strategy for ALF. Human primary hepatocytes are an ideal cell source for these methods. However, their high demand and superior viability prevent their widespread use. Hence, finding alternatives that meet the seed cell quality and quantity requirements is imperative. Stem cells with self-renewing, immunogenic, and differentiative capacities are potential cell sources. MSCs and its secretomes encompass a spectrum of beneficial properties, such as anti-inflammatory, immunomodulatory, anti-ROS (reactive oxygen species), anti-apoptotic, pro-metabolomic, anti-fibrogenesis, and pro-regenerative attributes. This review focused on the recent status and future directions of stem cell-based strategies in BAL for ALF. Additionally, we discussed the opportunities and challenges associated with promoting such strategies for clinical applications.

Advancements in Disease Modeling and Drug Discovery Using iPSC-Derived Hepatocyte-like Cells

Serving as the metabolic hub of the human body, the liver is a vital organ that performs a variety of important physiological functions. Although known for its regenerative potential, it remains vulnerable to a variety of diseases. Despite decades of research, liver disease remains a leading cause of mortality in the United States with a multibillion-dollar-per-year economic burden. Prior research with model systems, such as primary hepatocytes and murine models, has provided many important discoveries. However, progress has been impaired by numerous obstacles associated with these models. In recent years, induced pluripotent stem cell (iPSC)-based systems have emerged as advantageous platforms for studying liver disease. Benefits, including preserved differentiation and physiological function, amenability to genetic manipulation via tools such as CRISPR/Cas9, and availability for high-throughput screening, make these systems increasingly attractive for both mechanistic studies of disease and the identification of novel therapeutics. Although limitations exist, recent studies have made progress in ameliorating these issues. In this review, we discuss recent advancements in iPSC-based models of liver disease, including improvements in model system construction as well as the use of high-throughput screens for genetic studies and drug discovery.

Changes in the hepatic differentiation potential of human mesenchymal stem cells aged in vitro

Background

Due to their multipotency and ability for self-renewal, human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) hold great promise for generating hepatocytes. Previous research has successfully generated hepatocytes from early-passage [i.e., passage (P)3] hUC-MSCs; however, the populations of early-passage cells are limited, and these cells cannot produce sufficient functional hepatocytes for large-scale application in clinical therapy. Thus, a thorough investigation of the hepatic differentiation potential of in vitro-aged hUC-MSCs is needed.

Methods

hUC-MSCs were passaged in vitro and subcultured every 3 days up to P8, and their morphology, proliferative capacity, liver-specific marker expression, and liver function at the end of each passage were analyzed. The efficiency of the hepatogenic differentiation of hUC-MSCs driven by a functional hit 1 (FH1)-based strategy at different passages was also evaluated.

Results

The in vitro-aged hUC-MSCs gradually displayed morphological inhomogeneity, had reduced proliferative capability, and exhibited senescent properties while maintaining adipogenic and osteogenic differentiation potential. Additionally, senescence also decreased the expression of messenger RNA (mRNA) levels in albumin (ALB) and alpha 1-antitrpsin (A1AT) in these cells and their relative protein expression, which is the marker of a mature hepatocyte. The liver function of the in vitro-aged hUC-MSCs also deteriorated gradually. Finally, the percentage of hepatocyte-like cells (HLCs) generated from in vitro-aged hUC-MSCs reduced significantly, and the mature hepatocyte functions, such as ALB secretion, glycogen synthesis, low-density lipoprotein (LDL) intake, and indocyanine green (ICG) uptake, also changed.

Conclusions

hUC-MSCs possess mature hepatocytes’ specific markers and functions, which change gradually as they undergo cell senescence. Due to the loss of these properties within in vitro subcultures, the hepatic differentiation efficiency of in vitro-aged hUC-MSCs decreased dramatically in the late passage (P8). The current study provides valuable information can inform future research on liver disease.