Robust Differentiation of Human iPSCs into a Pure Population of Adipocytes to Study Adipocyte-Associated Disorders.

Recent advances in induced pluripotent stem cell (iPSC) technology have allowed the generation of different cell types, including adipocytes. However, the current differentiation methods have low efficiency and do not produce a homogenous population of adipocytes. Here, we circumvent this problem by using an all-trans retinoic-based method to produce mesenchymal stem cells (MSCs) in high yield. By regulating pathways governing cell proliferation, survival, and adhesion, our differentiation strategy allows the efficient generation of embryonic bodies (EBs) that differentiate into a pure population of multipotent MSCs. The high number of MSCs generated by this method provides an ideal source for generating adipocytes. However, sample heterogeneity resulting from adipocyte differentiation remains a challenge. Therefore, we used a Nile red-based method for purifying lipid-bearing mature adipocytes using FACS. This sorting strategy allowed us to establish a reliable way to model adipocyte-associated metabolic disorders using a pool of adipocytes with reduced sample heterogeneity and enhanced cell functionality.

Loss of FOXA2 induces ER stress and hepatic steatosis and alters developmental gene expression in human iPSC-derived hepatocytes.

FOXA2 has been known to play important roles in liver functions in rodents. However, its role in human hepatocytes is not fully understood. Recently, we generated FOXA2 mutant induced pluripotent stem cell (FOXA2-/-iPSC) lines and illustrated that loss of FOXA2 results in developmental defects in pancreatic islet cells. Here, we used FOXA2-/-iPSC lines to understand the role of FOXA2 on the development and function of human hepatocytes. Lack of FOXA2 resulted in significant alterations in the expression of key developmental and functional genes in hepatic progenitors (HP) and mature hepatocytes (MH) as well as an increase in the expression of ER stress markers. Functional assays demonstrated an increase in lipid accumulation, bile acid synthesis and glycerol production, while a decrease in glucose uptake, glycogen storage, and Albumin secretion. RNA-sequencing analysis further validated the findings by showing a significant increase in genes associated with lipid metabolism, bile acid secretion, and suggested the activation of hepatic stellate cells and hepatic fibrosis in MH lacking FOXA2. Overexpression of FOXA2 reversed the defective phenotypes and improved hepatocyte functionality in iPSC-derived hepatic cells lacking FOXA2. These results highlight a potential role of FOXA2 in regulating human hepatic development and function and provide a human hepatocyte model, which can be used to identify novel therapeutic targets for FOXA2-associated liver disorders.

Derivation of a human induced pluripotent stem cell line (QBRIi007-A) from a patient carrying a homozygous intronic mutation (c.613-7T>G) in the SLC2A2 gene.

Fanconi Bickel Syndrome (FBS) is an autosomal recessive disease resulting from mutations in the SLC2A2 gene, encoding the GLUT2. FBS patients develop diabetes mellitus. Using non-integrating Sendai virus, we generated an induced pluripotent stem cell (iPSC) line, QBRIi007-A, carrying the c.613-7 T>G homozygous mutation in intron 5 of the SLC2A2 gene from a 19-year-old female with FBS and diabetes. The iPSC line was characterized for pluripotency, differentiation potential, genomic integrity, and genetic identity. This iPSC line provides a useful cell model to understand the role of GLUT2 in the disease development and to discover new drug candidates.

Generation of a human induced pluripotent stem cell line (QBRIi009-A) from a patient with a heterozygous deletion of FOXA2.

FOXA2 is a transcription factor, playing an important role during development. We established an induced pluripotent stem cell (iPSC) line, QBRIi009-A, using non-integrating Sendai virus from a 4-year-old boy, displaying a complex clinical phenotype. Molecular karyotyping and cytogenetics confirmed a de novo proximal 20p11.2 deletion with a reciprocal translocation between the short arm of chromosome 6 and 20. The deleted region (~969 kb) contains only one gene, FOXA2. The generated hiPSC line was fully characterized for its pluripotency and its genetic identity. This iPSC line provides a useful model to study FOXA2 role during human development and in disease pathogenesis.