Umbilical cord mesenchymal stromal cells in serum-free defined medium display an improved safety profile

Abstract

Background: Safety evaluations in preclinical studies are needed to confirm before translating a cell-based product into clinical application. We previously developed a serum-free, xeno-free, and chemically defined media (S&XFM–CD) for the derivation of clinical-grade umbilical cord-derived MSCs (UCMSCs), and demonstrated that intraperitoneal administration of UCMSCs in S&XFM–CD (UCMSCS&XFM−CD) exhibited better therapeutic effects than UCMSCs in serum-containing media (SCM, UCMSCSCM). However, a comprehensive investigation of the safety of intraperitoneal UCMSCS&XFM−CD treatment should be performed before clinical applications. Methods: In this study, the toxicity, immunogenicity and biodistribution of intraperitoneally transplanted UCMSCS&XFM−CD were compared with UCMSCSCM in rats via general vital signs, blood routine, blood biochemistry, subsets of T cells, serum cytokines, pathology of vital organs, antibody production and the expression of human-specific gene. The tumorigenicity and tumor-promoting effect of UCMSCS&XFM−CD were compared with UCMSCSCM in nude mice. Results: We confirmed that intraperitoneally transplanted UCMSCS&XFM−CD or UCMSCSCM did not cause significant changes in body weight, temperature, systolic blood pressure, diastolic blood pressure, heart rate, blood routine, T lymphocyte subsets, and serum cytokines, and had no obvious histopathology change on experimental rats. UCMSCS&XFM−CD did not produce antibodies, while UCMSCSCM had very high chance of antibody production to bovine serum albumin (80%) and apolipoprotein B-100 (60%). Furthermore, intraperitoneally injected UCMSCS&XFM−CD were less likely to be blocked by the lungs and migrated more easily to the kidneys and colon tissue than UCMSCSCM. In addition, UCMSCS&XFM−CD or UCMSCSCM showed no obvious tumorigenic activity. Finally, UCMSCS&XFM−CD extended the time of tumor formation of KM12SM cells, and decreased tumor incidence than that of UCMSCSCM. Conclusions: Taken together, our data indicate that UCMSCS&XFM−CD display an improved safety performance and are encouraged to use in future clinical trials.