Evaluation of ex vivo produced endothelial progenitor cells for autologous transplantation in primates

Meng Qin, Xin Guan, Yu Zhang, Bin Shen, Fang Liu, Qingyu Zhang, Yupo Ma, Yongping Jiang

Autologous transplantation of endothelial progenitor cells (EPCs) is a promising therapeutic approach in the treatment of various vascular diseases. We previously reported a two-step culture system for scalable generation of human EPCs derived from cord blood CD34+ cells ex vivo. Here, we now apply this culture system to expand and differentiate human and nonhuman primate EPCs from mobilized peripheral blood (PB) CD34+ cells for the therapeutic potential of autologous transplantation. The human and nonhuman primate EPCs from mobilized PB CD34+ cells were cultured according to our previously reported system. The generated adherent cells were then characterized by the morphology, surface markers, nitric oxide (NO)/endothelial NO synthase (eNOS) levels and Dil-acetylated low-density lipoprotein (Dil-Ac-LDL) uptake/fluorescein isothiocyanate (FITC)-lectin binding actives. Furthermore, the efficacy and safety studies were performed by autologous transplantation via hepatic portal vein injection in a nonhuman primate model with acute liver sinusoidal endothelial cell injury. The mobilized PB CD34+ cells from both human and nonhuman primate were efficiently expanded and differentiated. Over 2 × 108 adherent cells were generated from 20 mL mobilized primate PB (1.51 × 106 ± 3.39 × 105 CD34+ cells) by 36-day culture and more than 80% of the produced cells were identified as EPCs/endothelial cells (ECs). In the autologous transplant model, the injected EPC/ECs from nonhuman primate PB were scattered in the intercellular spaces of hepatocytes at the hepatic tissues 14 days post-transplantation, indicating successful migration and reconstitution in the liver structure as the functional EPCs/ECs. We successfully applied our previous two-step culture system for the generation of primate EPCs from mobilized PB CD34+ cells, evaluated the phenotypes ex vivo, and transplanted autologous EPCs/ECs in a nonhuman primate model. Our study indicates that it may be possible for these ex-vivo high-efficient expanded EPCs to be used in clinical cell therapy.