CD34+ selected cells in clinical transplantation.

The CD34 antigen is expressed by early hematopoietic stem cells and progenitors and is detected on the surface of approximately 1% of bone marrow mononuclear cells [1-3]. Several monoclonal antibody-based methods have been developed to isolate these cells from clinical samples of bone marrow or peripheral blood based on their expression of this antigen, utilizing either biotin-avidin affinity, panning or immunomagnetic beads. Roughly 50% of CD34+ cells, with 20-90% purity, are recovered from clinical samples using these methods. Several clinical trials have demonstrated hematopoietic recovery using CD34+ selected cells to support high dose therapy. CD34+ cells may be useful in several areas of clinical stem cell transplantation, including purging of tumor cells, T cell depletion, stem cell expansion and gene therapy. This paper reviews the current methods for purification of CD34+ cells from clinical samples and discusses potential uses of these cells in transplantation.