Abstract 4146342: Endothelial cells injured by hyperglycemia are rescued by P53 silenced bone marrow derived mesenchymal stromal cells (BM-MSC) derived secretome by improving cellular mitochondrial function.

Introduction: Diabetes is associated with endothelial cell dysfunction. Studies have demonstrated that endothelial progenitor cells (EPCs) and mature endothelial cells (EC) are susceptible to apoptosis in hyperglycemic environment, however EPC start to undergo apoptosis within 48 hrs whereas ECs take upto 4 weeks. We in the past have shown that p53 gene silencing prevents EPC senescence in hyperglycemia and helps vascular regeneration. We have also shown that p53 silenced hematopoeitic CD34+ve EPC therapy helped tissue and vascular regeneration in hyperglycemia (25mmol). Our goal was to test whether conditioned media (CM) obtained from p53 silenced human stem cells (non-hematopoitic source) can also improve cell survival&regeneration. Methods: We examined BM-MSCs and Adipose tissue MSCs (ADMSCs) derived CM to explore cell free therapeutics. Ad-human-P53 (TP53)-shRNA was used to silence P53 and Ad-scrambled-null-shRNA was used as control. To collect CM, the MSCs were cultured for 5 days, in serum-free media, followed by transduction with Ad-p53sh or Ad-null. After transduction, cells were cultured in 2% exosome free FBS media for only 48h and the collected supernatant was concentrated 10-fold to obtain the CM. Endothelial regeneration was tested following CM treatment on human endothelial cells (HECs) using endothelial wound healing assay kit (Cell Biolabs CBA-120-T). We compared CM obtained from null and p53sh BM-MSCs and ADMSCs on HEC , which was exposed to hyperglycemia for 2-3 weeks, using wound-healing assay (n=5). Results: Anti-apoptosis/ Proliferation capacity of the p53sh BMMSC-CM was 2.5-fold more compared to p53sh-ADMSC-CM. Post BM-MSC-CM treatment of hyperglycemia exposed endothelial cells, we noted a 4-fold increase in VEGFA mRNA expression and 2.2-fold increase mitochondrial-SOD (SOD2), compared to null transduced BMMSC derived CM. Other mitochondrial genes are being investigated and indicate a similar trend. Furthermore exosomes derived from p53 BMMSC-CM appear to have the protective effect on hyperglycemia exposed HEC vs non exosomal portion. Conclusion: p53sh-BMMSC-CM appears to have better anti-apototic effect compared to p53sh-ADMSC-CM. This finding allows us to generate relatively larger quantities of CM vs CM from p53sh EPCs. Cell-free CM or exosomes from CM obtained from p53sh BM-MSC cells may have a therapeutic role in treating vascular complications of diabetes with mitochondrial function improvement as a possible mechanism.