The Effect of Physical Conditions on the Transportation of Peripheral Blood Progenitor (PBPC) Products.

The viability of transported PBPC products has not been studied extensively. Commonly, PBPC products are transported at a concentration of >200 x10⁹/l in containers with −20^oC ice packs. Continuous temperature monitoring has shown that the temperatures of these products stays at <10^oC for less than 24 hours and reaches room temperature by 48 hours. Samples of freshly collected PBPC from 12 allogeneic donors were studied for various viability parameters during storage for up to 96 hours. The effects of storage time, concentration of cells, temperature, and storage in gas-permeable bags were studied. Trypan-blue exclusion and double fluorescence for 7-AAD and CD34 were used for viability assessment. Over a wide range of temperatures and storage times, the viable CD34⁺ assay was more sensitive to damage than trypan-blue exclusion (mean Δ 10.7%, p<0.0001 in paired t-test). The viable CD34⁺ assay was routinely used in parallel with CFU-GM cultures. No difference in survival of viable CD34⁺ cells or CFU-GM was found whether cells were incubated for 48hr in test-tubes or in gas-permeable bags. When cells at 200 x 10⁹/l were incubated for 48hr at room temperature, the mean viability decreased to 19% and 6% of starting values of viable CD34⁺ cells and CFU-GM, respectively. Serial dilution to 25 x 10⁹/l improved the survival to 81% and 51% respectively. Similarly, incubation at lower temperatures led to better survival of CD34⁺ cells and CFU-GM: 67% and 18% at 17^oC, 80% and 50% at 13^oC, and 95% and 86% at 4^oC. At 200 x10⁹/l and 22^oC the survivals of CD34⁺ cells and CFU-GM were 74% and 21% at 24hr, 19% and 7% at 48hr, 7% and 6% at 72hr, and 3% and 13% at 96hr. The effects of concentration, temperature and duration of storage were all significant (p<0.05). Transportation at 4^oC leads to the best survival of CD34⁺ cells and CFU-GM, in particular at a low concentration. If transportation at a slightly higher temperature is necessary, dilution of the PBPC product will enhance the survival of CD34⁺ cells and CFU-GM. Proliferative assays such as CFU-GM appear the most sensitive parameters of PBPC survival, and should be included in the validation process of PBPC transportation.