Characterization and Differentiation of Sorted Human Fetal Pancreatic ALDH^hiand ALDH^hi/CD133⁺Cells Toward Insulin-Expressing Cells

Abstract

The enzyme aldehyde dehydrogenase (ALDH) is found in developing and multipotent cell populations, and is important for the production and regulation of retinoic acid, which controls β-cell differentiation in the pancreas. The role of ALDH-expressing cells in the formation of endocrine-like cells and co-localization with the putative stem cell marker CD133 has not been examined during human pancreatic development. This study focuses on the co-expression of CD133 on ALDH cells from the human fetal pancreas (18-22 weeks of fetal age) with transcription factors (TFs) central to endocrine cell development. Fluorescence-activated cell sorting demonstrated that cells with high ALDH activity (ALDH) had increased co-expression of CD133 and endocrine-lineage TFs when compared with cells with low ALDH (ALDH) expression. Hormone-expressing (insulin, somatostatin) and ductal cells (CK19) were noted in the ALDH population, while mesenchymal (vimentin) and endothelial (CD31) markers were predominantly found in ALDH cells. Culture of sorted ALDH or ALDH/CD133 cells resulted in loss of endocrine TF, insulin, and CK19 expression. The formation of cell clusters from cultured ALDH or ALDH/CD133 cells led to restored CK19 expression and showed endocrine TFs and insulin expression. In summary, pancreatic ALDH cells contain a heterogeneous CD133-enriched population with a subset of β-cell associated markers in the developing human pancreas.

Aldehyde Dehydrogenases: Not Just Markers, but Functional Regulators of Stem Cells

“…When transplanted into mouse embryos, ALDH br central acinar/terminal duct cells, but not their ALDH dim counterparts, contribute to both exocrine and endocrine lineages in the developing pancreas [48]. It also has been shown that the ALDH br subpopulation of human fetal pancreatic cells contains a heterogeneous population enriched in CD133 + cells and a subset of markers associated with β -cells in the developing human pancreas [49].…”

“…Various combinations of markers including ALDH, CD34, CD133, Sca-1, CD44, and integrin α 2 β 1 have been used to identify putative stem cells, as exemplified by ALDH br CD34 + human cardiac atrial stem cells [53, 54], ALDH br CD133 + human fetal pancreatic stem cells [49], ALDH br Sca-1 + murine prostatic stem cells [50], and ALDH br CD44 + human epidermal stem/progenitor cells [52]. It is worth noting that, besides ALDH, other stem cell-associated markers, such as CD133 and CD44, may also play functional roles in stem cells [193, 194].…”

Islet organoid as a promising model for diabetes

“…There is a longstanding debate regarding whether the adult pancreas contains stem or progenitor cells. Several particular cell groups have been proposed as pancreatic progenitor or progenitorlike cells, which have the ability to differentiate into insulinsecreting cells in vitro, including Nestin-positive cells isolated from mouse pancreas (Wei et al, 2012), cells with high aldehyde dehydrogenase enzyme activity sorted from human fetal and adult pancreas (Loomans et al, 2018;Oakie et al, 2018), and P2RY1-and ALK3-positive cells sorted from human pancreatic ducts (Qadir et al, 2018;Qadir et al, 2020). Recently, a new population of Procr + endocrine progenitors was identified from adult mouse islets (Wang et al, 2020).…”

Stem Cell Therapy for Diabetes: Beta Cells versus Pancreatic Progenitors

“…The initial characterization of this population indicates the potential of PDX1-/NKX6.1+ cells to generate islet endocrine cells [23]. In vitro expanded islets undergoing de-differentiation have been shown to generate INS+ beta cells on extended culture [43,44], as well as progenitor cells with high aldehyde dehydrogenase activity extracted from the fetal and adult pancreas [45,46]. Additionally, the pancreatic duct serves as a reservoir of a subset of progenitor cells possessing ability to transdifferentiate to beta cells [47,48].…”