A simple, efficient washing procedure for cryopreserved human hematopoietic stem cells prior to reinfusion

We describe our experience with a washing procedure used on cryopreserved, thawed bone marrow (BM) and peripheral blood stem cell (PBSC) grafts prior to autologous transplantation in 50 and 12 patients respectively. The procedure consists of a stepwise dilution with 2% human serum albumin and centrifugation performed either manually or using a blood cell processor (Cobe 2991). In vitro studies showed mean recoveries of 80.8% for BM nucleated cells and 73.9% for BM hematopoietic progenitors (CFU-GM). The corresponding recoveries for PBSC were 89.1 and 93.9%. After 4 h storage at +20 degrees C of the manipulated grafts, no significant loss of CFU-GM was observed. We conclude that the technique is simple and efficient for washing large numbers of hematopoietic stem cells. This method may avoid the clinical complications often arising with unwashed grafts.