Increased blood volume and CD34(+)CD38(-) progenitor cell recovery using a novel umbilical cord blood collection system

A major problem with the use of umbilical cord/placental blood (UCB) is the limited blood volume that can be collected from a single donor. In this study, we evaluated a novel system for the collection of UCB and analyzed the kinetics of output of hematopoietic stem cells in the collected blood. Sequential UCB fractions were collected from 48 placentas by gravity following common procedures. When UCB flow was ended, collection was continued using the device. Nucleated cell (NC) density in each fraction was evaluated and the expression of CD34, CD38 and other hematopoietic markers was assessed by flow cytometry. The total collected volume was 60.9 +/- 26.2 ml (mean +/- SD, range 17-141.5). The device yield (volume collected using the device/total volume) was 26.5 +/- 15.1%. No significant difference was observed in NC count in sequential fractions. A significant increase in CD34(+) cell content in sequential fractions and a 2.07 +/- 1.18-fold increase in the percentage of CD34(+) cells in the last versus first fraction were observed. Furthermore, within the CD34(+) population, the percentage of CD38(-) pluripotent stem cells in the first fraction was 3.24 +/- 1.39, while in the last fraction it raised to 34.43 +/- 22.62. Thus, at the end of a collection performed following current procedures, further blood rich in the most primitive progenitor cells can be recovered. Therefore, the optimization and standardization of collection procedures are required to obtain maximal recovery from each placenta and increase the percentage of UCB units suitable for clinical use.

Phenotypic characterization of immunomagnetically purified umbilical cord blood CD34+ cells

This study describes the multilineage differentiation pattern of purified CD34+ stem cells obtained from human umbilical cord blood. CD34+ cells were collected from 49 umbilical cord blood samples. Following immunomagnetic purification, cells were double stained with anti CD34 and CD71, CD61, CD7, CD19, CD33, CD36 and triple stained with anti CD34, CD38 and HLA-DR. Analysis were performed using a FACScan flow cytometer. After purification, the mean CD34+ cells' purity was 85.49 +/- 7.08%. Several subpopulations of umbilical cord blood CD34+ cells were identified indicating different lineage commitment. The majority of CD34+ cells expressed both CD38 and HLA-DR (91.74 +/- 3.76%), while those lacking CD38 were 3.43 +/- 2.12% (CD38-DR+) and 1.81 +/- 1.54% (CD38-DR-). These data were compared to the expression of lineage commitment markers on purified CD34+ cells from 5 mobilized peripheral blood samples. The percentage of peripheral blood CD34+CD38-DR+) and CD34+CD38-DR- cells was significantly lower than umbilical cord blood, 0.24 +/- 0.18% and 0.04 +/- 0.03% respectively. The knowledge and standardized of umbilical cord blood CD34+ cells phenotype is critical since umbilical cord blood volume is limited. The homogeneity of CD34+ subpopulation phenotype suggests that monitoring of lineage differentiation antigens may not be relevant for clinical use of umbilical cord blood samples. However, the observed higher percentage of pluripotent CD34+38- stem cells in umbilical cord blood compared to peripheral blood, that might explain the successful clinical use of umbilical cord blood even when low number of cells are used, candidates these antigens as the predictive parameter for clinical use of umbilical cord blood samples.

Cell cycle synchronization of FRTL5 cells. A physiological model system

We describe a "physiological" cell cycle synchronization model system. FRTL5 cells, TSH-dependent for proliferation, were starved from TSH. The cell cycle phases and the expression of markers associated to different cycle phases were evaluated. TSH starvation blocks proliferation without provoking death and induces virtually all the cells to accumulate in G0/G1 phase. TSH readdition allows 30% of these cells to enter the S phase. DNA topoisomerase II 170-kDa isoform is not expressed in G0/G1 synchronized cells while it is expressed in logarithmic growing cells. The 180-kDa isoform is not expressed in G0/G1 synchronized cells while it is expressed in 20% of logarithmic growing cells regardless of the cycle phase. c-myc mRNA is not expressed in G0/G1 synchronized cells while it is detectable upon TSH readdition. This system provides a tool for the analysis of events associated with the G0/G1 phase and the transition from G0/G1 to S phase.