Compromised endothelial progenitor cell exosomal communication with endothelial cells in hypertension ischemia conditions.

We have previously demonstrated that endothelial progenitor cell (EPC) derived exosomes (EPC-EXs) can protect endothelial cells (ECs) against hypoxia injury. Given that EX function varies upon the cellular status and EPC function is declined in hypertension, we speculate the function of EPC-EXs is altered in hypertension-ischemia conditions. Here, we studied the EPC-EX mediated communications of EPCs with ECs in hypertension-ischemia conditions. EPC-EXs were prepared from the bone marrow EPCs of wild-type (WT) and hypertensive renin transgene (R+) mice (WT-EPC-EXs and R-EPC-EXs, respectively). To mimic hypertension-ischemia injury, ECs were challenged with angiotensin II (Ang II; 10^-6 M) plus hypoxia (1% O₂ for 6 h) and reoxygenation (21% O₂ for 24 h). To determine the function of EPC-EXs, ECs were co-cultured with EXs during the reoxygenation period. EX uptake effciency, EC viability, and angiogenic function were assessed. We found that: (1) The incorporation effciency of R-EPC-EXs by ECs was significantly decreased compared to the WT-EPC-EXs. (2) Ang II plus hypoxia reoxygenation-injured ECs displayed decreased cell viability, increased cell apoptosis, and compromised angiogenic ability, which were alleviated by R-EPC-EXs. (3) WT-EPC-EXs elicited better effects than R-EPC-EXs on protecting ECs from hypertension plus hypoxia injury. In conclusion, our data have demonstrated that EPC-EXs mediated communication of EPCs and ECs is compromised in hypertension-ischemia conditions, suggesting that impairment of EPC exosomal communication might contribute to the exaggerated cerebral ischemia injury in hypertension-associated ischemic stroke.