Induction of the CD24 Surface Antigen in Primary Undifferentiated Human Adipose Progenitor Cells by the Hedgehog Signaling Pathway

Francesco Muoio,Tiziano Tallone,Yves Harder,Stefano Panella

doi:10.3390/biologics1020008

Francesco Muoio, Tiziano Tallone + Show 2 more

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https://doi.org/10.3390/biologics1020008

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Abstract

In the murine model system of adipogenesis, the CD24 cell surface protein represents a valuable marker to label undifferentiated adipose progenitor cells. Indeed, when injected into the residual fat pads of lipodystrophic mice, these CD24 positive cells reconstitute a normal white adipose tissue (WAT) depot. Unluckily, similar studies in humans are rare and incomplete. This is because it is impossible to obtain large numbers of primary CD24 positive human adipose stem cells (hASCs). This study shows that primary hASCs start to express the glycosylphosphatidylinositol (GPI)-anchored CD24 protein when cultured with a chemically defined medium supplemented with molecules that activate the Hedgehog (Hh) signaling pathway. Therefore, this in vitro system may help understand the biology and role in adipogenesis of the CD24-positive hASCs. The induced cells’ phenotype was studied by flow cytometry, Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR) techniques, and their secretion profile. The results show that CD24 positive cells are early undifferentiated progenitors expressing molecules related to the angiogenic pathway.

Highlights

In 2002, Zuk et al published a study describing a novel adult stem cell population isolated from adipose tissue [1,2]
To give the Hh signaling pathway the possibility to operate without interference from other cell transduction circuits, we developed a basal-defined xeno- and serum-free medium called UrSuppe-24 (US-24)
Once the confluence was reached, the usual cell culture medium was replaced by UrSuppe-24 (US-24), a precisely defined xeno- and serum-free medium derived from UrSuppe, which we developed to induce the CD24 antigen in human adipose stem cells (hASCs)

Summary

Introduction

In 2002, Zuk et al published a study describing a novel adult stem cell population isolated from adipose tissue [1,2]. At the beginning of the new millennium, almost simultaneously with the first description of ASCs, several research groups reported the existence of other adult stem cells of mesodermal origin found in other organs or tissues This led the International Society of Cellular Therapy (ISCT) to publish a position paper to give standard guidelines to researchers studying this type of stem cell [9]. Shortly after, the researchers realized that these adult stem cells of mesodermal provenance are different and have peculiarities depending on the tissue of origin This new vision, which concerns the ASCs, was expressed in a position article in a joint statement of the International Federation for Adipose Therapeutics and Science (IFATS) and the ISCT [10]. Cutting-edge technologies have confirmed a substantial difference between ASCs and bone marrow-derived mesenchymal stem cells (BM-MSCs), the two most studied types of adult stem cells of mesodermal origin [11,12]

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