Evaluation of clinical scale CD34⁺ cell purification: experience of 71 immunoaffinity column procedures

Abstract

Seventy-one mobilised PBSC collections were subject to CD34⁺ cell purification using the CEPRATE SC^® stem cell concentration system. The overall median purity of CD34⁺ cells was 69% (6–93%). CD34⁺ cell, and GM-CFC recoveries were 52% (8–107%) and 36% (3–118%). Purity was logarithmically related to the input percentage of CD34⁺ cells and starting requirements were established of 1% CD34 cell content for optimal purity and a minimum of 2 × 10⁶/kg CD34⁺ cells to ensure recovery of our minimum engraftment threshold of 1 × 10⁶/kg CD34⁺ cells. Reduction of the washing steps reduced non-specific cell losses and shortened the procedure but did not affect progenitor cell recovery. Purified CD34⁺ cells were reinfused following high-dose therapy in 35 patients. The median time to neutrophil recovery of 0.5 × 10⁹/l was 12 (10–23) days and to the attainment of platelet independence was 13 (7–100) days. The risks of delayed platelet recovery were related to the CD34⁺ cell dose infused and were identical to the risks when non-purified PBSC collections were used. In conclusion, purification of CD34⁺ cells using the CEPRATE device is reliable and the purified product results in prompt engraftment. The cell losses that occur do however restrict its use in many patients.