Evaluations of bioantioxidants in cryopreservation of umbilical cord blood using natural cryoprotectants and low concentrations of dimethylsulfoxide.

Transplantation using hematopoietic stem cells from umbilical cord blood (UCB) is a life-saving treatment option for patients with select oncologic diseases, immunologic diseases, bone marrow failure, and others. Often this transplant modality requires cryopreservation and storage of hematopoietic stem cells (HSC), which need to remain cryopreserved in UCB banks for possible future use. The most widely used cryoprotectant is dimethylsulfoxide (Me(2)SO), but at 37 degrees C, it is toxic to cells and for patients, infusion of cryopreserved HSC with Me(2)SO has been associated with side effects. Freezing of cells leads to chemical change of cellular components, which results in physical disruption. Reactive oxygen species (ROS) generation also has been implicated as cause of damage to cells during freezing. We assessed the ability of two bioantioxidants and two disaccharides, to enhance the cryopreservation of UCB. UCB was processed and subjected to cryopreservation in solutions containing different concentrations of Me(2)SO, bioantioxidants and disaccharides. Samples were thawed, and then analysed by: flow cytometry analysis, CFU assay and MTT viability assay. In this study, our analyses showed that antioxidants, principally catalase, performed greater preservation of: CD34+ cells, CD123+ cells, colony-forming units and cell viability, all post-thawed, compared with the standard solution of cryopreservation. Our present studies show that the addition of catalase improved the cryopreservation outcome. Catalase may act on reducing levels of ROS, further indicating that accumulation of free radicals indeed leads to death in cryopreserved hematopoietic cells.

Screening for antimalarial activity in the genus Potomorphe.

Ethanolic extracts (CEE) of leaves from Potomorphe umbellata and Potomorphe peltata, popularly said to have antimalarial capacity, were submitted to the 4-day suppressive test in Plasmodium berghei-infected mice. The CEE of P. umbellata administered either orally (250 and 1250 mg/kg) or subcutaneously (100 and 500 mg/kg) evidenced strong antimalarial activity, significantly reducing the levels of parasitaemia in a dose-dependent manner. On the other hand, the CEE of P. peltata was ineffective in lowering the parasitemic levels in malarious mice, which had been treated either orally (500 mg/kg) or subcutaneously (20, 100 and 500 mg/kg). An ethanol extract of the dry whole plant of P. peltata was also inactive.