Avaliação da trealose como crioprotetor natural de células-tronco hematopoiéticas de sangue de cordão umbilical e placentário

• Autor(a) principal: Motta, Juliana Pessanha Rodrigues
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/7767
• topic: Cord blood; Trehalose; Cryopreservation; Liposome; DMSO; Sangue de cordão; Trealose; Lipossomos; DMSO; Genética humana; Células-tronco; Criopreservação; Citologia e Biologia celular; CNPQ::CIENCIAS BIOLOGICAS::MORFOLOGIA::CITOLOGIA E BIOLOGIA CELULAR

The umbilical cord blood (UCB) has been used as a source of primitive hematopoietic stem cells (HSC) to reconstitute the hematopoiesis. Most often, it is required the cryopreservation of HSC, which remain frozen in banks for possible future use. For cryopreservation of HSC, the chemical reagent dimethylsulfoxide (DMSO) has been used as a cryoprotectant. Many organisms in nature have a capacity of survive freezing and dehydration by accumulating disaccharides, so the trehalose, has been actively investigated as an alternative cryoprotector, other damage which is very common during freezing is oxygen free radicals formation which decreases the cellular viability after thawing, so the addition of bioantioxidants in the solution of cryopreservation of cells is very important. This study was divided into two phases: first, we evaluated the results obtained with the addition of antioxidants in the solution for cryopreservation of cord blood cells and the second phase: evaluate the hypothesis that the cryopreservation solution containing intracellular and extracellular trehalose improves recovery and viability of cord blood stem cells after cryopreservation. UBC was processed and subjected to cryopreservation solutions containing for the first phase: solutions with different concentrations of DMSO (10%, 5% and 2.5%), as well as combinations of DMSO (5%, 2.5 %) with a disaccharide (60 mmol/L), ascorbic acid and/or catalase (10mg/mL), and for the second phase: solutions containing different concentrations of DMSO (10% and 2.5%), as well as combinations of DMSO (2.5%) with intracellular trehalose (trehalose was introduced into the cell by means of liposomes) and solutions containing extra and intracellular trehalose without DMSO, stored for two weeks in N2L, and thawed. The thawed cells were assessed by flow cytometry, MTT and colony forming units (CFU) assays. In the first phase of the study our analysis showed catalase improved the preservation CD34+ and CD123+ cells, cell viability and CFU compared to standard cryopreservation solution. In the second phase, after testing of all test we observed that the solution containing intra/extracellular trehalose and DMSO showed superior capacity of maintaining the cell viability/integrity in relation to the others, the solution containing intra-and extracellular trehalose without DMSO, obtained a result that can be compared with its control (2.5% DMSO), and that the solution containing only intracellular trehalose did not generate satisfactory results. The catalase can act on reducing the levels of reactive oxygen species in the solution for cryopreservation of HSC of UCB reducing the damage it caused, trehalose must be present on both sides of the cells during the freezing process. Future clinical trials are needed to confirm that it may be a potential cryoprotectant of stem cells from cord blood, which can totally replace the DMSO in cryopreservation solution, eliminating the side effects from the infusion of cryopreserved products in patients already suffering from the disease base.