BACKGROUND : The cryopreservation of HPCs in DMSO has been practiced by cord blood (CB) banks worldwide. Inevitably, some detriment to biologic function occurs as the result of freezing injuries and DMSO toxicity. Trehalose, a disaccharide, is a natural cryoprotectant in organisms capable of surviving extreme dehydration and cold. The objective of this study was to establish the cryopreservation of CB under preclinical conditions using trehalose as a supplement to DMSO.
STUDY DESIGN AND METHODS : In a preclinical protocol, the effects of 5-percent trehalose with 10-percent DMSO or 5-percent DMSO on the cryopreservation of CB MNCs or nucleated cells (NCs) were further evaluated. The read-out system consisted of a panel of HPCs: early progenitors (CFU-GEMM, long-term culture-initiating cells [LTC-IC]) and committed progenitors (CFU-GM, CFU/BFU-E, CFU-megakaryocyte [CFU-MK]). The homing and engraftment capacity of these cells were assessed in nonobese diabetic (NOD)-SCID mice.
RESULTS : Trehalose increased the recoveries of CFU-GM, CFU/BFU-E, CFU-GEMM, and LTC-IC by over 7.25 percent (mean), 11.9 percent, 19.2 percent, and 12.9 percent, respectively, when compared with those in paired CB samples cryopreserved in 10-percent DMSO. Freezing and thawing reduced the yields of CFU-MK by 35.5 percent (mean) and 28.4 percent in MNC and NC samples, respectively, and the inclusion of 5-percent trehalose significantly retrieved these progenitor cells to over 90 percent of fresh samples. The improved recovery of functional HPLs was reflected by their multilineage engraftment in NOD-SCID mice.
CONCLUSION : Trehalose at 5 percent significantly ameliorates the cryopreservation of CB progenitor cells at a preclinical protocol. The increased recoveries of these cells might potentially improve the engraftment outcomes of CB transplants.