Leukocyte recovery from umbilical cord blood by poligeline.

Umbilical cord blood (UCB) collected at delivery is a source of transplantable stem/progenitor cells; it represents an alternative to bone marrow to restore hematopoiesis in patients affected by malignant and non-malignant disease. Therefore, large-scale UCB banks would be a natural complement to bone marrow donor registries. Storage of unmanipulated whole UCB units requires a great number of liquid nitrogen containers. Separation of leukocytes allows UCB storage in smaller space, thus lowering banking costs; unfortunately, UCB processing may cause significant losses of stem cells. We report about the use of poligeline to remove erythrocytes from UCB units. After erythrocyte sedimentation at 1xg (30' or 40') or 50xg, leukocyte-rich supernatant was collected and centrifuged to recover the leukocyte pool in view of stem cell transplantation. Erythrocyte depletion was always satisfactory, ranging from 82.6% to 88.9%, but 1xg sedimentation for 40' enabled us to achieve the best CD34+ cell recovery (mean value 80.5%). The proposed UCB-processing method allowed us to lower the final sample volume down to 1/10 of the initial one, in this way making UCB banking feasible. Erythrocyte depletion took place directly in the collection bag, thus reducing microbial contamination risk.