Preconditioning of bone marrow mesenchymal stem cells by prolyl hydroxylase inhibition enhances cell survival and angiogenesis in vitro and after transplantation into the ischemic heart of rats

Abstract

IntroductionPoor cell survival and limited functional benefits have restricted the efficacy of bone marrow mesenchymal stem cells (BMSCs) in the treatment of myocardial infarction. We showed recently that hypoxia preconditioning of BMSCs and neural progenitor cells before transplantation can enhance the survival and therapeutic properties of these cells in the ischemic brain and heart. The present investigation explores a novel strategy of preconditioning BMSCs using the Hypoxia-inducible factor 1α (HIF-α) prolyl hydroxylase inhibitor dimethyloxalylglycine (DMOG) to enhance their survival and therapeutic efficacy after transplantation into infarcted myocardium.MethodsBMSCs from green fluorescent protein transgenic rats were cultured with or without 1 mM DMOG for 24 hours in complete culture medium before transplantation. Survival and angiogenic factors were evaluated in vitro by trypan blue staining, Western blotting, and tube formation test. In an ischemic heart model of rats, BMSCs with and without DMOG preconditioning were intramyocardially transplanted into the peri-infarct region 30 minutes after permanent myocardial ischemia. Cell death was measured 24 hours after engraftment. Heart function, angiogenesis and infarct size were measured 4 weeks later.ResultsIn DMOG preconditioned BMSCs (DMOG-BMSCs), the expression of survival and angiogenic factors including HIF-1α, vascular endothelial growth factor, glucose transporter 1 and phospho-Akt were significantly increased. In comparison with control cells, DMOG-BMSCs showed higher viability and enhanced angiogenesis in both in vitro and in vivo assays. Transplantation of DMOG-BMSCs reduced heart infarct size and promoted functional benefits of the cell therapy.ConclusionsWe suggest that DMOG preconditioning enhances the survival capability of BMSCs and paracrine effects with increased differentiation potential. Prolyl hydroxylase inhibition is an effective and feasible strategy to enhance therapeutic efficacy and efficiency of BMSC transplantation therapy after heart ischemia.

Insight on stem cell preconditioning and instructive biomaterials to enhance cell adhesion, retention, and engraftment for tissue repair

“…Dimethyloxalylglycine (DMOG) is a prolyl hydroxylase inhibitor that permits HIF1a pathway signaling, leading to upregulation of survival genes and growth factors [111]. Liu et al reported that exposure of BM-MSCs to DMOG mimicked the effects of hypoxia preconditioning by enhancing the secretion of proteins and increasing cell survival in vitro [121]. Once transplanted into myocardially infarcted rats, DMOG-preconditioned BM-MSCs showed less apoptosis, smaller infarct size, and enhanced cardiac function, suggesting that pretreatment with DMOG or other prolyl hydroxylase inhibitors may be a valuable therapeutic approach to mimic hypoxic preconditioning.…”

Towards the standardization of stem cell therapy studies for ischemic heart diseases: Bridging the gap between animal models and the clinical setting

“…Cell refinement can be achieved, for instance, by density centrifugation [13], magnetic-(MACS) [26,33] or fluorescence-activated cell sorting (FACS) [99] or by pre-in vitro priming [8,13,27,33,58,99,100]. Density centrifugation is often used to isolate mononuclear cells (BMMNC) from BM cell suspension [13,75], while MACS and FACS achieve a higher degree of selectivity by picking up cells according to their surface markers (cluster of differentiation, CD).…”

“…Density centrifugation is often used to isolate mononuclear cells (BMMNC) from BM cell suspension [13,75], while MACS and FACS achieve a higher degree of selectivity by picking up cells according to their surface markers (cluster of differentiation, CD). MACS and FACS can also be used to achieve sub-populations by negative selection, whereby cells are labeled and discarded according to the expression of markers which are not of interest for a particular experiment [33,99]. Finally, in vitro preconditioning is used to obtain sub-populations endowed to survive in the harsh conditions of the myocardium.…”

“…One example is by changing/adapting the culture conditions, such as decreasing the chamber oxygen to levels below 5% to achieve a hypoxic environment [27,33]. In addition, it was already reported a different approach to mimic hypoxia by the means of prolyl hydroxylase inhibition [99]. It is expected that cells growing in a low oxygen tension atmosphere are more prepared to endure in the hypoxic myocardium as they are more resistant to apoptosis.…”

“…That is attributed to the oxygensensitive hypoxia-inducible transcription factor 1α (HIF-1α), which is stabilized by low levels of oxygen and degraded by prolyl hydroxylases. HIF-1α dimerizes with HIF-1β to form a heterodimer that translocates to the nucleus and induces a pro-survival and pro-angiogenic gene expression program that protects cells from hypoxia [27,33,99]. Another reported strategy for cell refinement is the enrichment of BMMNC with higher in vitro migratory capacity towards the chemokine SDF-1, which also appears to be correlated with higher proliferative, pro-angiogenic and anti-fibrotic properties [13].…”