Volume reduction of cord blood by Hetastarch for long-term stem cell banking.

As of November 1997, a total of 2098 cord blood (CB) units are stored in the CB bank Düsseldorf (mean volume, total nucleated cell count, BFU-E, CFU-GM, CFU-GEMM, CD34+ cells). Considering a threshold of 2 x 10(7) nucleated cells (NC)/kg body weight required for transplantation and 10 +/- 5 x 10(8) NC per CB unit, 100%, 67% and 25% of the CB units contain sufficient NC to engraft patients of 10 kg, 35 kg and 50-70 kg, respectively. Within the last 3 years with the majority during 1997, a total of 4000 preliminary searches, 450 extended unit reports were submitted to the CB bank by fax or World Wide Web and 36 units were delivered upon request for transplantation to various centers. 1940 CB units were stored unseparated, frozen in two freezing bags requiring 15 400-l liquid nitrogen tanks for long-term storage. Therefore, the volume reduction method applying Hetastarch (HES) according to Rubinstein's protocol was introduced into the routine processing of the CB units. Until now 158 CB units with a mean recovery of 85 +/- 13% for nucleated cells, 86 +/- 12% and 84 +/- 13% for CFC and CD34+ cells, respectively, were processed and stored with a total volume of 25 ml in one freezing bag.