Insights and hopes in umbilical cord blood stem cell transplantations

Over 20.000 umblical cord blood transplantations (UCBT) have been carried out around the world. Indeed, UCBT represents an attractive source of donor hematopoietic stem cells (HSCs) and, offer interesting features (e.g., lower graft-versus-host disease) compared to bone marrow transplantation (BMT). Thereby, UCBT often represents the unique curative option against several blood diseases. Recent advances in the field of UCBT, consisted to develop strategies to expand umbilical stem cells and shorter the timing of their engraftment, subsequently enhancing their availability for enhanced efficacy of transplantation into indicated patients with malignant diseases (e.g., leukemia) or non-malignant diseases (e.g., thalassemia major). Several studies showed that the expansion and homing of UCBSCs depends on specific biological factors and cell types (e.g., cytokines, neuropeptides, co-culture with stromal cells). In this review, we extensively present the advantages and disadvantages of current hematopoietic stem cell transplantations (HSCTs), compared to UBCT. We further describe the importance of cord blood content and obstetric factors on cord blood selection, and report the recent approaches that can be undertook to improve cord blood stem cell expansion as well as engraftment. Eventually, we provide two majors examples underlining the importance of UCBT as a potential cure for blood diseases.