Automatic washing of thawed haematopoietic progenitor cell grafts: a preclinical evaluation

Autologous haematopoietic progenitor cell (HPC) is a prerequisite for high-dose chemotherapy in treatment of several haematologic and non-haematologic malignancies. HPCs are collected by apheresis and cryopreserved until infusion. Postinfusion adverse events have been in part related to the dimethyl sulphoxide (DMSO) used as cryoprotectant. The aim was to evaluate (i) an automated sequential washing procedure for DMSO removal in thawed HPC grafts and (ii) washing solutions in replacement of hydroxyethyl starch (HES)-based solutions.

A total of 26 HPC bags cryopreserved with 10% DMSO and intended for disposal were used. The Sepax-2 (Biosafe, Eysins, Switzerland) was evaluated using a sequential washing procedure. Outcomes were CD34⁺ cell recovery and viability after washing.

The Ringer lactate supplemented or not with albumin 2·5-5% presented satisfactory results compared with HES solution in terms of CD34⁺ cell recovery and viability after washing. However, the apparition of aggregates led us to renounce to these alternative solutions. Using HES solution and a sequential washing of three bags, we showed the elimination of 95% of the DMSO, a postwash viable CD34⁺ cell recovery of 79·9 ± 9·4% and a total nucleated cell viability of 66·5 ± 9·3%.

The preclinical evaluation of an automated sequential washing procedure for DMSO removal in thawed HPC grafts has proven to be effective and comparable to previously published data. Despite our attempt to find an alternative solution to the HES solution, more efforts should be done on this side to reach a consensus on cryopreservation protocols.