ABO-mismatched marrow transplantation: removal of mismatched donor red blood cells by "washing" with recipient's matched red blood cells in a closed system

Fully automated, clinical-grade bone marrow processing: a single-centre experience

BACKGROUND

Clinical grade processing of harvested bone marrow is required in various clinical situations, particularly in the management of ABO mismatching in allogeneic haematopoietic stem cell transplantation (HSCT) and in regenerative medicine.

MATERIAL AND METHODS

We report a single-centre experience using a fully automated, clinical grade, closed system (Sepax, Biosafe, Switzerland). From 2003 to 2015, 125 procedures were performed in our laboratory, including buffy-coat production for HSCT (n=58), regenerative medicine in an orthopaedic setting (n=54) and density-gradient separation in a trial for treatment of critical limb ischaemia (n=13).

RESULTS

Buffy coat separation resulted in a median volume reduction of 85% (range, 75-87%), providing satisfactory red blood cell depletion (69%, range 30-88%) and a median recovery of CD34 cells of 96% (range, 81-134%) in the setting of allogeneic HSCT. Significantly greater volume reduction (90%; range, 90-92%) and red blood cell depletion (88%; range, 80-93%) were achieved by the new SmartRedux software released for Sepax2, validated in the last eight allogeneic HSCT. The density gradient separation programme resulted in complete red blood cell depletion associated with high CD34 recovery (69%; range, 36-124%). No reactions related to the quality of the product were reported. Time to engraftment following allogeneic HSCT was in the normal range. No cases of microbiological contamination related to the manipulation were reported.

DISCUSSION

Clinical grade, automated bone marrow manipulation with Sepax was shown to be effective, giving operator-independent results and could be used for a broad range of clinical applications.

[Erythrocyte removal from bone marrow by density gradient separation using the COBE 2991 cell processor with the triple-bag processing set]

ABO-incompatible bone marrow transplantation requires red blood cell depletion. Lots of laboratory adopted the technique of density gradient centrifugation (Ficoll-hypaque) using the COBE 2991 cell processor with simple-bag processing set. However, tubing of this set is not adapted to the currently available peristaltic pumps. Moreover, two other sets are required: one for the buffy-coat and one for postgradient cell washing. We developed a method using triple-bag processing set to conduct whole-step procedure (concentration, Ficoll and washing). Peristaltic PVC tubing is provided in one line of the set allowing a safe processing without several connections thus reducing risks of microbial contamination. First, we used buffy-coat of total blood for training, then, we carried out red cell depletion of healthy bone marrow donors. The red blood cell depletion was 97.9+/-1.1% and CD34+ recovery was 89.6+/-8.7%. These results are very close to those obtained with the simple-bag set (red cell depletion.=94.0+/-6.8% and CD34+ recovery=95.9+/-20.3%). We conclude that the triple-bag system, very little used in France, is practical, simplified the manipulation and is more safety than the simple-bag set.