Background
Endothelial dysfunction, characterized by diminished endothelial progenitor cell (EPC) function and flow-mediated vasodilation (FMD), is a clinically significant feature of heart failure (HF). Mesenchymal stem cells (MSCs), which have pro-angiogenic properties, have the potential to restore endothelial function. Accordingly, we tested the hypothesis that MSCs increase EPC function and restore flow-mediated vasodilation (FMD).
Methods
Idiopathic dilated and ischemic cardiomyopathy patients were randomly assigned to receive autologous (n = 7) or allogeneic (n = 15) MSCs. We assessed EPC-colony forming units (EPC-CFUs), FMD, and circulating levels of vascular endothelial growth factor (VEGF) in patients before and three months after MSC transendocardial injection (n = 22) and in healthy controls (n = 10). Findings: EPC-colony forming units (CFUs) were markedly reduced in HF compared to healthy controls (4 ± 3 vs. 25 ± 16 CFUs, P < 0.0001). Similarly, FMD% was impaired in HF (5.6 ± 3.2% vs. 9.0 ± 3.3%, P = 0.01). Allogeneic, but not autologous, MSCs improved endothelial function three months after treatment (Δ10 ± 5 vs. Δ1 ± 3 CFUs, P = 0.0067; Δ3.7 ± 3% vs. Δ-0.46 ± 3% FMD, P = 0.005). Patients who received allogeneic MSCs had a reduction in serum VEGF levels three months after treatment, while patients who received autologous MSCs had an increase (P = 0.0012), and these changes correlated with the change in EPC-CFUs (P < 0.0001). Lastly, human umbilical vein endothelial cells (HUVECs) with impaired vasculogenesis due to pharmacologic nitric oxide synthase inhibition, were rescued by allogeneic MSC conditioned medium (P = 0.006). Interpretation: These findings reveal a novel mechanism whereby allogeneic, but not autologous, MSC administration