Study of a new device for washing and concentrating cryopreserved hematopoietic stem cells and mononuclear cells: a single center experience.

BACKGROUND AIMS: Cryopreserved cellular products, as parts of hematopoietic progenitor cell (HPC) transplants, mononuclear cell reinjections for donor lymphocyte infusion or extracorporeal photopheresis, can be washed before being reinjected into the patient or infused directly, depending on local practices. The aim of washing is to reduce the incidence and severity of adverse reactions (ARs) due to the dimethyl sulfoxide (DMSO) used as a cryoprotective agent and other factors, such as dead cell debris. At the authors' cell therapy laboratory (CTL) in Poitiers, France, as in 76% of Etablissement Français du Sang (EFS) CTLs, all cryopreserved products undergo thawing in a water bath followed by washing with the COBE 2991. As this device will soon cease to be available, an alternative process needs to be assessed. METHODS: The authors compared two closed systems: the authors' semi-automatic system using the traditional centrifugation method (COBE 2991) and an automated device using spinning membrane filtration (Lovo). A total of 72 HPC bags available for research were used. The authors first performed a paired comparison, processing one or two HPC bags washed by each device. A second study was carried out to compare two different washing solutions generally used by EFS CTLs along with variable storage conditions. Finally, the authors studied the efficiency of the Lovo with three or four thawed bags. The main parameters studied were viable CD34+ cell recovery and viability, CD3+ cell recovery, stability up to 6 h after washing, DMSO elimination and center feasibility. RESULTS: The Lovo device showed better CD34+ cell recovery compared with the COBE 2991 while maintaining CD34+ viability and stability over 6 h. Moreover, Lovo efficiency seemed to be independent of the number of thawed bags processed and washing solution used in the authors' study. CD3+ cell recovery met the authors' internal specifications (cell recovery >50%), with similar results seen when processing with either the COBE 2991 or Lovo. Additionally, on average, 97% of DMSO was removed after washing with Lovo, minimizing the risk of ARs. The storage conditions post-processing indicated preferred storage conditions of 7 ± 3°C. Finally, if processing time seemed shorter using COBE 2991 for one bag washed, the Lovo device required only one staff member regardless of the number of HPC bags processed. CONCLUSIONS: The Lovo device seems to provide an opportunity to standardize HPC processing, ensuring patient safety, with, on average, 97% of DMSO removed, while improving recovery of cells of interest and maintaining viability over time in case of delayed transplant. The Lovo device consequently seems to be a serious alternative to the COBE 2991.