Human mesenchymal stromal cells : biological characterization and clinical application

Abstract

This thesis focuses on the characterization of the biological and functional properties of human mesenchymal stromal cells (MSCs), isolated from different tissue sources. The differentiation capacity of MSCs from fetal and adult tissues has been tested and compared. Umbilical cord blood (UCB) has been investigated as a potential novel source of MSCs for clinical application and the immunomodulatory properties of UCB-derived MSCs have been characterized in comparison with those of MSCs of bone marrow (BM) origin. Moreover, it has been attempted to optimize the experimental conditions for MSC ex vivo expansion. Alternative culture methods, devoid of animal proteins, have been applied by introducing expansion procedures based on platelet-derived growth factors. The potential susceptibility of MSCs to undergo malignant transformation after long-term in vitro culture has been investigated and discussed in view of their clinical application, especially in immunocompromised hosts. The role of MSC therapy in the context of hematopoietic stem cell transplantation (HSCT) has been explored, focusing in particular on the co-transplantation of MSCs to promote engraftment of hematopoietic progenitors, and on the administration of MSCs for the treatment of steroid-resistant, severe acute graft-versus-host disease (GvHD). The role of MSCs in the treatment of inflammatory bowel diseases refractory to conventional therapies, as well as the concept for treating refractory autoimmune diseases has been discussed.