RESUMO
INTRODUCTION: Mesenchymal stem cells are obtained from a variety of sources, particularly bone marrow. These cells have great potential for clinical research due to their potential to regenerate tissue. As is well known, the cryopreservation process can store any cell type, particularly blood cells, for an indeterminate time. OBJECTIVE: The aim of this study was to analyze the efficiency of standard cryopreservation procedures for adult mesenchymal stem cells from bone marrow. METHODS: Mononuclear stem cells isolated from 10 Wistar male rats were cultivated for 4 weeks to obtain mesenchymal stem cells. The parameters considered in this study were trypan blue exclusion test and annexin V conjugated with 7-amino-actinomycin for flow cytometry before cryopreservation in liquid nitrogen vapor phase for 1 month and after thawing. RESULTS: The viabilities determined by the trypan blue exclusion test were 94.76% and 90.58%, and the flow cytometry assay (annexin V conjugated with 7-amino-actinomycin) were 85.52% and 66.25%, before cryopreservation and after thawing, respectively. CONCLUSIONS: Standard procedures for cryopreservation were not efficient for those cells. The flow cytometry assay was more sensitive than the trypan blue exclusion test to demonstrate nonviability.
