Stem cell collection filter system for human placental/umbilical cord blood processing

The hydroxyethyl starch method and the Top & Bottom method have been used worldwide for the volume reduction of human placental/umbilical cord blood (PCB) units. To simplify the preparation of nucleated cell (NC) concentrates, we developed a new filter device--the stem cell collection filter system (SCF SYSTEM)--which can collect mononuclear cells (MNC) at a high recovery rate.

The SCF SYSTEM consisted of a filter and two bags. Multilayered polyethylene terephthalate non-wovens, coated with a hydrophilic polymer, were used as filter media. PCB units were filtered by gravity (n = 12). Red blood cells, platelets and plasma were drained into the drain bag, and the NC trapped on the filter media was collected in the recovery bag by reverse washing. Recovered cell fractions were evaluated.

The volume of cell concentrate recovered was 27.4 +/- 2.2 ml (mean +/- SD, n = 12). The whole time required for processing was less than 30 min, and handling was very simple. The viability of recovered NC was 97.8 +/- 3.2%. The recovery of lymphocytes, monocytes and granulocytes was 79.5 +/- 16.9%, 79.8 +/- 20.4% and 39.0 +/- 19.5%, respectively. The recovery rate of granulocytes was significantly lower than that of monocytes and lymphocytes (P < or = 0.0001). The recovery rates of CD3+ cells, CD19+ cells and CD56+ cells were almost the same as that of MNC. The recovery rates of CD34+ cells, total colony-forming cells and long-term culture-initiating cells were 81.7 +/- 27.0% (n = 11), 80.8 +/- 27.7% (n = 12) and 75.0 +/- 18.4% (n = 2), respectively.

The new filter system was shown to be efficient for PCB processing, encompassing a very simple handling procedure with a good recovery of haematopoietic progenitor cells. Hence, the SCF SYSTEM is potentially useful for the volume reduction of PCB units for cord blood banking.