Cryopreservation of haematopoietic stem cells using a zwitterion

Zwitterions, which have low cytotoxicity among ionic liquids, are expected to be adopted in various applications across life sciences. We previously reported that zwitterions can be used as cryoprotectants, and that zwitterion/dimethyl sulfoxide (DMSO) aqueous solutions have high cryoprotective effects. Although cryopreservation of established cell lines has been performed using zwitterions, this method has not yet been applied to primary or stem cells. In this study, we verified whether primary haematopoietic stem cells (HSCs) could be efficiently cryopreserved using the zwitterion/DMSO aqueous solutions. The viable number of HSCs cryopreserved using zwitterion/DMSO/water (5/5/90, w/w/w) was comparable with that using LaboBanker™, a commercial freezing medium. The number was also higher than those after cryopreservation with DMSO/albumin solution/0.9% sodium chloride solution (10/20/70, v/v/v), which is commonly used in cryopreservation of HSCs. This suggests that the zwitterion/DMSO aqueous solution can be used for cryopreservation of HSCs. This article is part of the discussion meeting issue 'Ionic liquids and the future of soft materials'.