Down-regulation of gap junctions between bone marrow-derived endothelial
progenitor cells (EPC) and aortic endothelial cells in minipigs
Hung-I Yeh, Tin-Yi Tian, Yi-Chun Lin, Chi-Hau Chen, Yu-Jung Liu
Departments of Internal Medicine and Medical Research, Mackay Memorial Hospital
Background The role of gap junctions between EPC and native endothelial cells
during endothelial repair remained unclear. Methods and Results Bone
marrow-derived EPC and aortic endothelial cells were collected from 5 adult male
minipigs. Autologous cells were co-cultured for 24 to 72 hours and the expression of
gap junctions was examined by Western blotting and immunoconfocal microscopy. In
addition, the gap-junctional communication function was determined by
micro-injection. The results showed that bone marrow-derived EPC are positive for
UEA-I, uptake dil-acLDL, and express von Willebrand factor. Gap junctions in both
types of cells are predominantly made of connexin43 (Cx43), which is abundant and
with a good communication function. After co-culture, Cx43 protein was dramatically
decreased (33 % reduction, p <0.05) and the expression of Cx43 gap junctions was
reduced. Consistently, the communication function is also impaired. Conclusion Gap
junctions are down-regulated soon after the contact between bone marrow-derived
EPC and aortic endothelial cells, suggesting that the coordination of activity via gap
junctions between both types of cells is attenuated during this period of time.