Sysmex Journal International
CD34 Negative Hematopoietic Stem Cells
R&D, Sysmex Corporation of America
Gilmer Road 6699 RFD, Long Grove, IL 60047-9596, USA.
Two of the most exciting breakthroughs in hematopoietic stem cell (HSC) research were first, the discovery of CD34 expression on HSC, anti-CD34 antibody development and its applications in HSC transplantation; and secondly, the recent discovery of CD34 negative (CD34-) HSC. These discoveries, together with the success in studies of other stem cells, have resulted in the emergence of novel clinical treatments in stem cell regenerative medicine.
Following the studies of CD34 by Civin in 1988, CD34 antibody selected cells were successfully used for the reconstruction of hematopoiesis in lethally irradiated baboons. Since then, the CD34 marker and antibody have been widely used in the research of hematopoietic stem cell biology and clinical medicine, because of the effectiveness of anti-CD34 antibody selected cells in hematopoietic reconstitution for both animal investigation and human transplantation. These findings originally established the belief that hematopoietic stem cells are CD34 positive (CD34+). This is why the first report about CD34- HSC and its function in long-term lymphohematopoietic reconstitution by Osawa, and other consequent studies), have significantly challenged the existing concepts in stem cell biology and related clinical applications, such as stem cell transplantation and gene therapy. Therefore, it is not surprising that many HSC investigators have used some interesting titles for their papers, and commonly question marks have appeared in the article titles. For example:
･ CD34- stem cells as the earliest precursors of hematopoietic progeny
･ Hematopoietic stem cells: Are they CD34-positive or CD34-negative?
･ CD34+ or CD34-: Does it really Matter?
･ Who is hematopoietic stem cell: CD34+ or CD34-?
･ CD34: To select or not to select? That is the question
･ Development of the hematopoietic stem cell: Can we describe it?
Imaginably, these question marks also exist in the areas of HSC biology, its clinical applications, and future directions in stem cell investigations. This review will briefly summarize the recent progress in CD34- HSC research in basic and clinical medicine including CD34- HSC biology, clinical applications, expansion, and detection.
CD34- HSC, Biology, Clinical Application
Received 2 April, 2002; Accepted 12 April, 2002