Redefining the signaling pathways from pluripotency to pancreas development: In vitro β‐cell differentiation

Abstract

Pancreatic β‐cells are destroyed by the immune system, in type 1 diabetes (T1D) and are impaired by glucose insensitivity in type 2 diabetes (T2D). Islet‐cells transplantation is a promising therapeutic approach based on in vitro differentiation of pluripotent stem cells (PSCs) to insulin‐producing cells (IPCs). According to evolutionary stages in β‐cell development, there are several distinct checkpoints; each one has a unique characteristic, including definitive endoderm (DE), primitive gut (PG), posterior foregut (PF), pancreatic epithelium (PE), endocrine precursor (EP), and immature β‐cells up to functional β‐cells. A better understanding of the gene regulatory networks (GRN) and associated transcription factors in each specific developmental stage, guarantees the achievement of the next successful checkpoints and ensures an efficient β‐cell differentiation procedure. The new findings in signaling pathways, related to the development of the pancreas are discussed here, including Wnt, Activin/Nodal, FGF, BMP, retinoic acid (RA), sonic hedgehog (Shh), Notch, and downstream regulators, required for β‐cell commitment. We also summarized different approaches in the IPCs protocol to conceptually define a standardized system, leading to the creation of a reproducible method for β‐cell differentiation. To normalize blood glucose level in diabetic mice, the replacement therapy in the early differentiation stage, such as EP stages was associated with better outcome when compared with the fully differentiated β‐cells’ graft.

Automated optimization of endoderm differentiation on chip

“…A high concentration of AA during differentiation leads to the progression towards DE, whereas the absence of AA leads to mesoderm induction. 37 The relative concentration of AA/CHIR required to stimulate germ layer progression varies throughout the literature. Therefore, we investigated different concentrations of AA and CHIR on a single chip to determine the concentration that maximizes the specification of different cell types during DE patterning.…”

“…Both inductions require the presence of CHIR. 37 Indeed, this concentration effect of DE/mesodermal development could be recapitulated on the chip. In accordance with the literature, anterior-like DE cells were obtained at AA concentrations higher than 50 μM, based on the SOX17 and CER1 expression, whereas mesodermal-like cells were obtained upon removal of AA and increased CHIR concentration, based on the Brachyury-T expression.…”

Long noncoding RNA ANCR inhibits the differentiation of mesenchymal stem cells toward definitive endoderm by facilitating the association of PTBP1 with ID2

“…BMP signaling promotes DE formation while simultaneously suppressing pluripotency in ESCs/iPSCs 31 . bFGF promotes the epithelial to mesenchymal transition (EMT) 55 , which is a critical step during the acquisition of DE from iPS 56 . We speculated that exit from pluripotency and EMT progress were crucial for DE generation from ESCs/iPSCs but not MSCs.…”

Vav1 Sustains the In Vitro Differentiation of Normal and Tumor Precursors to Insulin Producing Cells Induced by all-Trans Retinoic Acid (ATRA)

“…The relationship between retinoids deficiency and the appearance of Type 1 diabetes mellitus, caused by reduction of the β-cell mass and function [54] as well as the evidence of ATRA-in duced restoration of Langerhans islet into diabetic rats [55] substantiate the crucial role of retinoids in β-cell formation in vivo. It is intriguing that in recent years the therapeutic approach to diabetes mellitus have explored new tools for the restoration of fully functional β-cells based on a set of strategies which include differentiation of multipotent stem cells [56][57][58], expansion of existing pools of cells, either from donors or by differentiating stem cells, and trans-differentiation of exocrine and endocrine pancreatic cells other than β-cells [59]. In this context, efforts directed to identify molecules that can trigger β-cell differentiation and replication look with renewed interest at the ATRA mediated signaling.…”