再论造血干细胞研究的若干新动向

Allogeneic hematopoietic stem cell transplantation (HSCT) is an effective and proven treatment for malignant and nonmalignant diseases. Most of the natural HSC allografts hardly show overall advantages of high engraftment, slight GVHD and rare relapse. The graft engineering including stem cell engineering to make a tailor-made graft ex vivo is promising to conquer all the risks of low engraftment, lethal GVHD and high relapse, which becomes the key program in current HSC research. To combine HSC allotransplant with gene therapy and immune therapy is the novel therapeutic strategy for malignancies, the real meaning of "cytotherapy" or "cell therapy" updated. The rapid expansion of umbilical cord blood banks (CBBs) makes the substantial increase of cord blood transplants (CBT) both possible and likely world-widely. In China, however, owing to lack of hematological pediatricians specified in HSCT and pediatric laminar-flow wards, clinical application rate of cord blood is extremely low despite of the high collection rate in the CBBs under the GMP standards. In evaluating a CBB, the release rate and the clinical efficacy of the released cord blood should be most emphasized as well as the banking quality control. In all CBBs worldwide, it is unworthy of mentioning the banking of umbilical cord blood for autologous transplant. Only one or two commercial companies in the world run it for profitable purpose to charge the donor parents regularly. It is because no autologous CBT can cure the inherited diseases and its efficacy of treating malignancies is doubtable since the cord blood is of weak immune competence against tumor and may be contaminated with autologous malignant or premalignant cells. Moreover, there is no report so far about how long the repopulating activity of cryopreserved hematopoietic stem/progenitor cells of cord blood can keep. No honest guarantee can be made about the effective quality and adequate amount of stem cells to meet the therapeutic requirement when used after a long storage.