Large scale purification of human blood CD34[sup+] cells from cryopreserved peripheral blood stem cells, using a nylon-fiber syringe system and immunomagnetic microspheres.

Isolation of large numbers of human peripberal blood CD34[sup+] cells could lead to therapeutic applications, including purging of malignant cells from blood cell transplantations, purging of T cells from allogeneic bone marrow, and even blood cell transplantation. This procedure has limitations if there are not sufficient numbers of progenitor cells in the leukapheresis concentrates available for selection after detection of tumor cells in apheresis products. Use of frozen/thawed peripheral blood mononuclear cell (PBMC) samples would make feasible pooling of two or even more stem cell harvests collected at different time points and the total number of CD34[sup+] progenitor cells available would increase. We established an efficient method for purification of CD34[sup+] cells from cryopreserved apheresis products, using a nylon-fiber syringe system and immunomagnetic microspheres. We compared purity, recovery rate and clonogenicity of CD34[sup+] cells purified from fresh (n = 22) and cryopreserved apheresis products (n=14), using a nylon-fiber syringe system and immunomagnetic microspheres. The purity of CD34[sup+] cells from cryopreserved products was less than that from fresh products (85.9 ± 14.4% vs 94.6 ± 10.0%), but the recovery rate of CD34[sup+] cells and colony-forming cells was comparable between fresh and cryopreserved products. One patient underwent grafting with peripheral blood CD34[sup-] cells selected after freezing, with good success. Therefore, these cells are capable of rapidly reconstituting hematopoiesis after high-dose chemotherapy. [ABSTRACT FROM AUTHOR]