Adjunctive reflections on history of hematopoietic stem cell study--editorial / 中国实验血液学杂志

ABSTRACT

The article reviews concisely around the history of hematopoietic stem cell research, basic and clinical, since its very beginning after the nuclear explosions at the end of the Second World War, that explains why the stem cell study in the world began with the hematopoietic stem cells and the existence of non-hematopoietic stem cell in vivo had been left out of account for many decades till 21st century. During 50-60s of the last century, it was known from the animal experiments that there must be hematopoietic stem cells existing in vivo and believed that the effective bone marrow transplant is actually the stem cell transplantation. It is reviewed how the basic studies of stem cell interacted with the clinical stem cell transplantation and how great the contribution was given to strongly push forward the development of contemporary stem cell biology and modern hematology from the basic studies especially in the immunological and molecular biological fields, for instance, the applications of HLA technology and monoclonal antibody produced, flow cytometry, and genetic recombinant cytokines, the novel technique for gene cloning, genomics, proteomics, and iRNA as well as bioinformatics. It has lead to the pluralistic cell therapy as a novel trend in stem cell transplantation as to combine immunotherapy and mesenchymal stem cells with the conventional stem cell transplants. This paper looks back in the past several decades, however, on every achievement of stem cell study that were usually accompanied with some idealistic one-sidedness or even errors in design and conclusion of some experiments. Usually it took a period of 2 or even 4 decades to clarify some basic idea, that seemed normal in the science development, for examples, the dividing line between the hematopoietic stem cell and progenitor cells, possibility to expand or clone the real stem cell ex vivo, and whether the majority of leukemias are originated from stem cell level, etc. Towards the end of 20th century, the greatest discovery was the existence of adult stem cells in adult tissues, which are no doubt the remnants from the embryonic development including all stages of embryonic stem cells, very earlier and later, hematopoietic and nonhematopoietic, and could be induced to differentiate into all kinds of tissue cells by proper ways in vitro. No evidence has really provided for the hypothesis of so called trans-differentiation or de-differentiation, which brought about strong calls in questions in the past 5 years. The problems in developing the clinical gene therapy by using hematopoietic stem cell as carrier of interested gene still remained to be solved so far. Because of the relatively weak base of related basic studies, the clinical application of gene therapy resulted in the failure of clinical practice with lots of lessons towards the end of last century. The whole history of stem cell study in the world was an endless process of continuous redress for theoretical ideas in stem cell biology that had never been consummate.