Purinergic Signaling Modulates Survival/Proliferation of Human Dental Pulp Stem Cells

Abstract

Human dental pulp stem cells (hDPSCs) reside in postnatal dental pulp and exhibit the potential to differentiate into odontoblasts as well as neurons. However, the intercellular signaling niches necessary for hDPSC survival and self-renewal remain largely unknown. The objective of this study is to demonstrate the existence of intercellular purinergic signaling in hDPSCs and to assess the impact of purinergic signaling on hDPSC survival and proliferation. hDPSCs were isolated from extracted third molars and cultured in minimum essential medium. To demonstrate responsiveness to ATP application and inhibitions by purinergic receptor antagonists, whole cell patchclamp recordings of ATP-induced currents were recorded from cultured hDPSCs. Immunofluorescence and enzymatic histochemistry staining were performed to assess purinergic receptor expression and ectonucleotidase activity in hDPSCs, respectively. To determine the effects of purinergic signaling on hDPSC, purinergic receptor antagonists and an ectonucleotidase inhibitor were applied in culture medium, and hDPSC survival and proliferation were assessed with DAPI staining and Ki67 immunofluorescence staining, respectively. We demonstrated that ATP application induced inward currents in hDPSCs. P2X and P2Y receptors are involved in the generation of ATP-induced inward currents. We also detected expression of NTPDase3 and ectonucleotidase activity in hDPSCs. We further demonstrated that purinergic receptors were tonically activated in hDPSCs and that inhibition of ectonucleotidase activity enhanced ATP-induced inward currents. Furthermore, we found that blocking P2Y and P2X receptors reduced-and inhibition of ecto-ATPase activity enhanced-the survival and proliferation of hDPSCs, while blocking P2X receptors alone affected only hDPSC proliferation. Autocrine/paracrine purinergic signaling is essential for hDPSC survival and proliferation. These results reveal potential targets to manipulate hDPSCs to promote tooth/dental pulp repair and regeneration.

Purinergic Signaling and Dental Orofacial Pain

“…Besides, mechanical stimulation-induced ATP release and ATP-mediated signal transmission from odontoblasts to trigeminal neurons have been demonstrated in vitro using co-culture models comprising of odontoblasts and trigeminal neurons [68,72]. The existence of autocrine/ paracrine mechanisms for ATP-involved purinergic signaling in cultured odontoblast-like stem cells is also confirmed [73]. Furthermore, external mechanical and thermal stimulation that mimics dentin hypersensitivity induces ATP release in a tooth perfusion model, while pharmacological blocking connexin and pannexin channels abolished external stimulation-induced ATP release in dental pulp [66].…”

Pathogenesis, diagnosis and management of dentin hypersensitivity: an evidence-based overview for dental practitioners

“…In addition, mechanically stimulated induction of ATP release and ATPmediated signal transmission from odontoblasts to trigeminal neurons has been demonstrated in vitro using co-culture models comprised of odontoblasts and trigeminal neurons [31,35]. Recently, the existence of autocrine/paracrine mechanisms for ATP-involved purinergic signaling in cultured odontoblast-like stem cells has been detected [36]. If this is the case, then the need for the presence of synaptic structures associated with odontoblasts for them to participate in the transmission of pain signals is obviated.…”

Role and application of stem cells in dental regeneration: A comprehensive overview

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