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.