A simple controlled-rate freezing method without a rate-controlled programmed freezer provides optimal conditions for both large-scale and small-scale cryopreservation of umbilical cord blood cells.

BACKGROUND: Umbilical cord blood (CB) is being used as a source of alternative HPCs for transplantation with increasing frequency. The goal of CB banks for unrelated transplantation is to provide good quality-controlled CB units that can be transplanted for HPCs into the largest possible number of patients. STUDY DESIGN AND METHODS: Large CB samples in freezing bags wrapped with insulators and small samples in cryotubes placed into double styrene-foam boxes were cryopreserved at -85 degrees C without a rate-controlled freezing machine, followed by storage in the liquid phase of nitrogen. After thawing these cells, the viability and recovery of cells, as well as the recovery rate of HPCs such as CD34+ cells, CFU-GM, and total CFU were evaluated. RESULTS: Measurement of the freezing rate in CB bags and cryotubes demonstrated that this simple method for cryopreservation of CB cells provided optimal conditions for both large-scale and small-scale cryopreservation. Recovery of CB progenitor cells after cryopreservation was also shown to be potentially acceptable when evaluated with CD34+ cells, CFU-GM, and total CFU. These results were comparable to the method using a rate-controlled programmed freezer. CONCLUSIONS: A simple method for cryopreservation of CB cells without a rate-controlled programmed freezer could provide a sufficient-enough potential for the transplantability of HPCs after thawing.

The absolute number of peripheral blood CD34+ cells predicts a timing for apheresis and progenitor cell yield in patients with hematologic malignancies and solid tumors.

Retrospective analysis was conducted in 51 autologous peripheral blood progenitor cell (PBPC) collections using the Spectra AutoPBSC System from patients with hematologic malignancies and solid tumors to study the predictive value of CD34+ cell counts in the peripheral blood for the yield of CD34+ cells in the apheresis product. The correlation coefficients for CD34+ cells microL(-1) of peripheral blood with CD34+ cell yield (x 10(6) kg(-1) of body weight and x 10(5) kg(-1) of body weight L(-1) of blood processed) were 0.903 and 0.778 (n=51 collections), respectively. Products collected from patients with CD34+ cell counts below 15 microL(-1) in the peripheral blood contained a median of 0.49 x 10(6) CD34+ cells kg(-1) (range: 0.05-2.55), whereas those with CD34+ cell counts more than 15 microL(-1) contained a median of 3.72 x 10(6) CD34+ cells kg(-1) (range: 1.06-37.57). From these results, a number of at least 15 CD34+ cells microL(-1) in the peripheral blood ensured a minimum yield of 1 x 10(6) CD34+ cells kg(-1) as obtained by a single apheresis procedure. The number of CD34+ cells in the peripheral blood can be used as a good predictor for timing of apheresis and estimating PBPC yield. With regard to our results, apheresis with a possibly poor efficiency should be avoided because the collection procedure is time-consuming and expensive.