Expression of ectonucleotidases in hDPSCs and effects of purinergic
signaling on hDPSC survival and proliferation. Immunofluorescence
staining for ecto-NTPDases in hDPSCs. Expression of NTPDase3 was
detected in hDPSCs (A). NTPDase2 was not detected in hDPSCs
(B). Scale bars 20 μm. (C) Inhibition of
ecto-NTPDases enhances purinergic signaling in hDPSCs. C1: ATP-induced
(3 μM) inward current in hDPSCs. C2: Application of ecto-NTPDase
inhibitor (100μM ARL 67156) enhanced the ATP-induced inward current in
hDPSCs. D: Effects of purinergic signaling on the survival and
proliferation of hDPSCs. DMSO exhibited deteriorating effects on
survival and proliferation of hDPSCs. As compared with the control
group, the cell number was significantly reduced at days 1, 2, and 3 in
DMSO vehicle control group. Interestingly, inhibition of
ectonucleotidase activity with 100mM ARL 67156 significantly increased
the number of hDPSCs in culture from day 1 to day 3, which suggest
trophic effects of ATP signaling on hDPSC survival and proliferation. As
compared with the DMSO group (vehicle control), blocking P2X receptors
with 100μM iso-PPADS had little effect on hDPSCs at
days 1 and 2; an inhibition effect on hDPSCs was observed at day 3.
Blocking P2X/P2Y receptors with suramin (100 μM) significantly reduced
the number of hDPSCs in culture at days 1, 2, and 3 (cell
proliferation). The data are presented as mean ± SD, n
= 7 in each group (analysis of variance); least significant difference
post hoc tests were performed at day 1, 2, or 3; and P
< 0.05 was considered statistically significant. *P
< 0.05, **P < 0.01, vs. control.
##P < 0.01, vs. DMSO.
$$P < 0.01, vs.
iso-PPADS. hDPSC, human dental pulp stem cell.