Purinergic Receptors Influence the Differentiation of Human Mesenchymal Stem Cells

Abstract

Adult stem cells, including adipose tissue-derived mesenchymal stem cells (MSCs) or ectomesenchymal dental follicle cells (DFCs), attract considerable attention for their potential to differentiate into lineages, which are of major interest in the field of Regenerative Medicine. Purinergic receptors exert a wide range of biological actions in many cell and tissue types through extracellular nucleotides. Little is known about P2 receptors in adult stem cells and changes in their expression levels during differentiation. All known P2 receptors have been investigated, and a variety of P2X and P2Y receptor subtypes were detected in MSCs. Studies investigating intracellular calcium levels on receptor stimulation demonstrated that the found P2 receptors are metabolically active. Interestingly, up- or downregulation of several P2 receptor subtypes at gene and protein level was observed during adipogenic and osteogenic differentiation, and the effect on differentiation was directly influenced by both the application of agonists/antagonists and apyrase-induced nucleotide cleavage. Here, we show for the first time that the combination of several P2 receptors plays a role in the differentiation of adult stem cells. The expression pattern of the P2 receptors, as well as their fate in differentiation, varies in stem cells of mesenchymal origin if compared with stem cells of ectomesenchymal origin. The subtypes P2X6, P2Y4, and P2Y14 seem to be pivotal regulators in MSC commitment, as they are regulated in both adipogenic and osteogenic differentiation of adipose tissue-derived stem cells and DFCs. These findings provide new insights into the differentiation processes and might reveal novel options to influence stem cell fate in future applications.

Purinergic signalling-evoked intracellular Ca2+ concentration changes in the regulation of chondrogenesis and skeletal muscle formation

“…In migratory CPCs, we have recently confirmed the mRNA and protein level expression of certain P2X (P2X 1,4,5,6,7 , but not P2X 2 and P2X 3 ) and all P2Y receptors [86]. Our results suggest the functionality of P2Y 1 , P2Y 2 , P2Y 4 , as well as P2X 4 and P2X 6 receptor subtypes in CPCs, which shows a very good correlation with previous data implicating the P2 receptor subtypes P2X 6 , P2Y 4 and P2Y 14 to be key regulators in MSC commitment [91].…”

“…Adipose tissue-derived stem cells (ATSCs) and dental follicle cells (DFCs) derived from the ectomesenchyme expressed some P2X (P2X 3,4,5,6,7 ) and all 8 P2Y receptor subtypes; interestingly, no mRNA transcripts of P2X 1 and P2X 2 receptors were identified in either cell type [90,91]. Extracellular nucleotides acting through P2 receptors (primarily P2X 6 , P2Y 4 , P2Y 6 , P2Y 13 and P2Y 14 ) are important modulators of MSC differentiation towards the osteogenic and adipogenic lineages [90][91][92]. The purinergic concept of MSC differentiation is further supported by a recent study showing substantial changes in ecto-nucleotide metabolism and ecto-nucleotidase expression profiles following chondrogenic differentiation of human umbilical cord-derived MSCs [93].…”

The role of purinergic signalling in the musculoskeletal system

“…Initial work showed that fluid flow induced vesicular release of ATP from human MSCs, which then stimulated proliferation via a P2 receptor-mediated increase in [Ca 2+ ]i (Riddle et al, 2007). More recent studies have shown that human MSCs express the P2X3-7 receptors and all P2Y receptors (Noronha-Matos et al, 2012;Zippel et al, 2012). P2 receptors and extracellular nucleotides are now thought to be important modulators of human MSC differentiation, with the P2X6, P2Y4, P2Y6 and P2Y14 receptors identified as playing pivotal roles in this process (Ferrari et al, 2011;Zippel et al, 2012;Noronha-Matos et al, 2012).…”

Purinergic signalling in the musculoskeletal system

“…UTP and, to a lesser extent, ATP were also shown to stimulate human MSC migration [290]. Human MSCs express all P2Y receptors and the P2X3-7 receptors [291,292]. Recently, extracellular nucleotides have been reported to modulate the differentiation of human MSCs, with the P2X6, P2Y 4 and P2Y 14 receptors identified as playing pivotal roles in this process [292,293].…”

“…Human MSCs express all P2Y receptors and the P2X3-7 receptors [291,292]. Recently, extracellular nucleotides have been reported to modulate the differentiation of human MSCs, with the P2X6, P2Y 4 and P2Y 14 receptors identified as playing pivotal roles in this process [292,293]. UDP activation of P2Y 6 receptors has also been shown to regulate the osteogenic differentiation of the primary MSCs from postmenopausal women [291].…”