Polymeric materials for ex vivo expansion of hematopoietic progenitor and stem cells

Hematopoietic stem and progenitor cells (HSPCs) are multipotent cells that have the specific capacity to self-renew and differentiate into all mature blood cells. Umbilical cord blood is a promising alternative source of HSPCs for allogeneic and autologous hematopoietic stem cell transplantation for the treatment of a variety of hematological disorders and as a supportive therapy for malignant diseases. However, the low number of HSPCs obtainable from a single donor of umbilical cord blood limits direct transplantation of umbilical cord blood to the treatment of pediatric patients because of the small volume of blood collected. Therefore, ex vivo HSPC expansion is necessary to produce a sufficient number of cells that can engraft and sustain long-term hematopoiesis. The native bone marrow microenvironment, a complex network of stromal cells and extracellular matrix (ECM), serves as a stem cell niche that regulates HSPC functions such as self-renewal, proliferation, homing, and fate choice. The importance of the topography of the tissue culture materials and of signaling molecules or specific functional groups immobilized on these materials has been taken into consideration in the recent development of HSPCs culture systems. We review the culture materials available for ex vivo HSPC expansion, and discuss the effects of their surface chemistry and topography on such expansion.