Background: The current available techniques to wash out DMSO from thawed umbilical cord blood (UCB) units are based essentially on standard centrifugation in an open system with various degrees of cell loss.
Study design and methods: We evaluated the capacity of a new automated closed device (Cytomate, Baxter, IL) to wash out the DMSO from thawed UCB units, saving at the same time the progenitor and accessory cells in terms of CD34+ cells and MNCs. We modified the standard software of the device and calculated the cell recovery on 25 UCB units. Moreover, we set up a new gas chromatographic method to exactly detect the DMSO removal rate.
Results: To evaluate the efficiency of the Cytomate device, we considered the postthawing (prewashing) versus postwashing cell recovery. The average recovery (%) in terms of total nucleated cells was 63.30 (range, 40.12-89.00), CD34+ cells was 70.20 (range, 11.51-89.01), CD3+ cells was 61.01 (range, 28.80-87.08), CD4+ cells was 62.53 (range, 30.62-96.73), CD8+ cells was 57.4 (range, 26.87-94.72), CD19+ cells was 63.33 (range, 39.10-90.33), CD16+/56+ cells was 70.67 (range, 8.91-98.40), CFU-GM was 74.33 (range, 20.23-98.60), total CFUs was 82.34 (range, 14.83-247.12), and viability was 89.67(range, 70.74-98.30). The total working time required was, on average, 15 minutes (range, 7-20).
Conclusions: The Cytomate device demonstrated a satisfying efficiency in cell recovery and in maintaining the clonogenic power of the UCB graft. The removal rate of DMSO was practically complete with evident advantages for the recipient. Finally, the entire manipulation performed in a closed system revealed to be safe, maintaining the sterility of the graft.