[Recovery of transplantable hematopoietic progenitor cells from the umbilical cord blood]

Cord blood (CB) is a source of transplantable hematopoietic progenitor cells (HPC); it represents an alternative to bone marrow to restore hematopoiesis in patients affected by malignant and non-malignant disease. Therefore, large-scale CB banks would be a natural complement to bone marrow donor registries. Storage of unmanipulated whole CB units requires a great number of liquid nitrogen containers. Separation of leukocytes allows CB storage in smaller space, thus lowering banking costs; unfortunately, CB processing may cause significant losses of stem/progenitor cells. We describe here a procedure for erythrocyte removal from CB units by 1 xg sedimentation on Emagel, a gelatin-based colloidal compound commonly used as plasma expander. The erythrocyte-depleted supernatant was collected and then centrifuged to recover the leukocyte pool. We evaluated erythrocyte depletion and leukocyte recovery after different sedimentation time (30, 45 and 60 min), on 139 CB units collected at delivery. All the considered parameters were improved by increasing sedimentation time. Erythrocyte depletion at 60 min was 86.0% and we recovered 93.3% of CD34+ cells. The proposed CB-processing method allowed us to collect a satisfactory amount of HPC in view of stem cell transplantation; it may have a potential role in UCB banking.