Impact of administering umbilical cord‐derived mesenchymal stem cells to cynomolgus monkeys with endometriosis

Abstract Purpose This study aimed to explore whether umbilical cord‐derived mesenchymal stem cells (UC‐MSCs) could be used as a therapeutic resource for endometriosis. Methods Of seven cynomolgus monkeys with endometriosis, five were administered UC‐MSCs (intervention group) and two were administered saline (control group). First, intravenous US‐MSC treatment was administered for three months. Second, weekly intravenous US‐MSC administration combined with monthly intraperitoneal US‐MSC administration was conducted for 3 months. Finally, weekly intraperitoneal US‐MSC administration was conducted for 3 months. The dose of UC‐MSCs was set to 2 × 106 cells/kg for all administration routes. Laparoscopic findings and serum cancer antigen 125 (CA125) levels were also evaluated. The Revised American Society for Reproductive Medicine classification was used for laparoscopic evaluation. Results Laparoscopic findings showed exacerbation of endometriosis after intraperitoneal UC‐MSC administration, although no changes were observed in the control group. Intravenous UC‐MSC administration decreased the level of CA125 in all monkeys; however, the difference was not significant. Intraperitoneal UC‐MSC administration significantly exacerbated endometriosis compared with intravenous administration (p = 0.02). Conclusions This study revealed that intraperitoneal UC‐MSC administration exacerbates endometriosis in a nonhuman primate model of the disease.