Applications of Apheresis Devices in Processing Bone Marrow Grafts

Abstract

ABO blood groups antigens are inherited independently from the human leukocyte antigen (HLA) system. Thus, up to 50% of allogeneic hematopoietic cell transplantations (HCT) are performed across the ABO blood group barrier. While peripheral blood hematopoietic progenitor cell (HPC) infusion can be performed mostly without any ABO-related complications, the infusion of bone marrow (BM) requires the implementation of safety precautions to avoid acute immune-mediated hemolysis during transplantation. Bone marrow processing techniques to remove either red blood cells (RBCs), or plasma, have been implemented decades ago. As autologous BM grafts have to be cryopreserved and stored in liquid nitrogen or its vapor phase, volume reduction before freezing is a pre-requirement. Over the last decades, various apheresis devices and protocols were developed for this purpose, partly using sedimentation agents or density gradient centrifugation with density gradient reagents to optimize processing results. These substances bear a potential risk for the BM cells and the recipients. In the beginning of the 1990s, apheresis technology was substantially improved. The latest innovations in this field were the Cobe Spectra (Terumo BCT) and Spectra Optia (Terumo BCT). With both devices, optimal results with respect to volume and RBC reduction and progenitor cell and mononuclear cell (MNC) recovery can be achieved. The Amicus (Fresenius) device reveals similar results but lacks a dedicated program for BM processing. Therefore, it should only be used by operators and physicians who are highly experienced with this device. BM collections from very small children may not fulfill the requirements for BM processing by apheresis in terms of minimal BM and RBC volume. In these cases, either RBC units can be added or a special device for cord blood processing (Biosafe Sepax device) can be used. An important issue for optimal progenitor cell and MNC selection by apheresis is a short transit time from the collection to the processing facility. Overnight storages should take place in a refrigerator at 4 °C ± 2 °C.