Factors Affecting Purification of CD34 + Peripheral Blood Stem Cells Using the Baxter Isolex 300i

A total of 201 patients with breast cancer, ovarian cancer, or hematological malignancies underwent mobilization of peripheral blood stem cells (PBSC) using chemotherapy and granulocyte-colony stimulating factor (G-CSF). Stem cell products were collected using the Baxter CS3000 pheresis machine. The Baxter Isolex 300i was used to perform 240 CD34⁺ cell separations on the apheresis products. Factors affecting yield and purity of the CD34⁺ cells were analyzed. Overall yield was 55% and overall purity was 91.7%. T cell contamination was limited to 0.43% of total cells. Variables including red blood cells (RBC) concentration, platelet concentration, CD34⁺ cell concentration, total WBCs selected, and time until processing had little effect on yields and purities. Installation of version 2.5 of the software in the Isolex 300i showed a modest improvement in yield and purity. Patients were reinfused with the cryopreserved CD34⁺ selected cells following high-dose chemotherapy. No infusion-related side effects were noted. Analysis of engraftment data using the CD34⁺-selected cells revealed an increased risk of delayed or failed platelet engraftment when <5.0 × 10⁶ CD34⁺ cells per kilogram were transplanted. The Baxter Isolex 300i provides reproducible CD34⁺ cell purification over a wide range of starting conditions. To provide prompt engraftment, >5.0 × 10⁶ CD34⁺ cells per kilogram should be infused for transplantation.