Stem cell harvesting and transplantation

Abstract

Allogeneic haematopoietic stem cell transplantation is an accepted treatment for a variety of malignant and non‐malignant diseases. Today, peripheral blood progenitor cells (PBPC) are increasingly used instead of bone marrow (BM) as stem cell source. Additionally, umbilical cord blood (UCB) has been established as an alternative source of donor cells. Many differences between the distinct stem cell sources do exist. PBPC contain a higher amount of CD34 + cells compared with BM and UCB, leading to more rapid engraftment with the disadvantage of a higher incidence of chronic graft‐versus‐host disease. In contrast to adults, children seem to have a better outcome after BM than PBPC transplantation. Therefore, especially patients with non‐malignant diseases and children should be transplated with BM. The disadvantage of the significantly lower CD34 + cells count in UCB products can be overcome by transplantation of two different units. The risk for allogeneic BM and PBPC donors is considered negligible. Lethal and serious side‐effects because of the harvest procedure are rarely reported with an incidence of 1/10 000 and 7·25/10 000, respectively. Granulocyte colony‐stimulating factor (G‐CSF) is widely administered to PBPC donors, but questions have been raised about its safety in respect of development of haematologic malignancies. To evaluate this concern, more long‐term safety data from larger prospective studies are needed. In the therapy with adult stem cells, a genotypic human leucocyte antigen (HLA) class I and class II identity between donor and recipient for the loci HLA‐A, HLA‐B, HLA‐C, HLA‐DR and HLA‐DQ is optimal; for UCB, HLA matching seems to be less important because of the relative low number of mature T cells in cord blood. The influence of other HLA‐linked or not HLA‐linked loci in stem cell transplantation (HLA‐DP, killer cell immunoglobulin receptor, …) is under investigation.