RESUMEN
The performance of a small-scale automated cryopreservation and storage system (Mini-BioArchive system) used in the banking of umbilical cord blood (UCB) units was evaluated. After thawing the units, the viability and recovery of cells, as well as the recovery rate of hematopoietic progenitor cells (HPCs) such as CD34+ cells, colony-forming unit-granulocyte-macrophage (CFU-GM), and total CFU were analyzed. Twenty UCB units cryopreserved using the automated system and stored for a median of 34 days were analyzed. Mean CD34+ cell viabilities before freezing were 99.8+/-0.5% and after thawing were 99.8+/-0.4% in the large bag compartments and 99.7+/-0.5% in the small compartments. The mean recovery values for total nucleated cells, CD34+ cells, CFU-GM, and total CFU were 94.8+/-16.0%, 99.3+/-18.6%, 103.9+/-20.6%, and 94.3+/-12.5%, respectively in the large compartments, and 95.8+/-25.9%, 106.8+/-23.9%, 101.3+/-23.3%, and 93.8+/-19.2%, respectively in the small compartments. A small-scale automated cryopreservation and storage system did not impair the clonogenic capacity of UCB HPCs. This cryopreservation system could provide cellular products adequate for UCB banking and HPC transplantation.
Asunto(s)
Criopreservación/instrumentación , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/fisiología , Antígenos CD34 , Bancos de Sangre , Conservación de la Sangre , Supervivencia Celular , Células Cultivadas , Centrifugación por Gradiente de Densidad , Ensayo de Unidades Formadoras de Colonias , Criopreservación/métodos , Dextranos , Dimetilsulfóxido , Femenino , Sangre Fetal , Citometría de Flujo , Congelación , Humanos , Técnicas In Vitro , Nitrógeno , Factores de TiempoRESUMEN
The aim of this study was to evaluate how a simple method of cryopreservation influences the quality of CD34+ cells in umbilical cord blood (UCB). The cells were dispensed into a double-compartment freezing bag, cryopreserved at -85 degrees C without a rate-controlled programmed freezer, and stored in the liquid phase of nitrogen. The viability of the CD34+ cells before freezing and after thawing was assessed by flow cytometry with 7-aminoactinomycin D and by colony-forming assays. Twenty UCB units cryopreserved for a median of 92 days were analyzed. Mean CD34+ cell viabilities before freezing were 99.8% +/- 0.4% and after thawing were 99.5% +/- 0.8% in large chambers, 99.6% +/- 0.5% in small chambers, and 99.4% +/- 0.6% in sample tubes. The mean values from colony-forming assays of the viable CD34+ cells before freezing were 30.7 +/- 6.8 (colony-forming units-granulocyte-macrophage [CFU-GM] per 100 viable CD34+ cells) and 68.5 +/- 14.8 (total CFUs per 100 viable CD34+ cells). The CFU-GM and total CFU values after thawing were, respectively, 32.7 +/- 9.0 and 66.0 +/- 13.4 in large chambers, 32.4 +/- 8.1 and 64.5 +/- 16.1 in small chambers, and 30.9 +/- 5.4 and 64.7 +/- 12.4 in sample tubes. The results of the colony-forming assays before freezing and after thawing were not significantly different. Our findings overall indicated that our simple method for the cryopreservation of UCB cells without a rate-controlled programmed freezer does not impair the clonogenic capacity of UCB progenitor cells. This cryopreservation method could provide cellular products adequate for hematopoietic stem cell transplantation.