In the present study, we have established Dextertype long-term cultures (D-LTC) from human umbilical cord blood (UCB) and followed the kinetics of different hematopoietic progenitor cells (HPCs)-including multipotent (colony forming unit [CFU]-Mixture), erythroid (CFU-erythroid, BFU-E), and myeloid (CFU-granulocyte, CFU-macrophage, CFU-granulocyte/macrophage) progenitors as well as of morphologically recognizable erythroid, myeloid and lymphoid cells-during a nineweek culture period. D-LTC were also established from adult bone marrow (BM) as controls. On day 0, both UCB and BM showed similar total numbers of HPCs (about 310/10 5 cells), however, UCB showed a higher proportion of primitive HPCs (i.e., CFU-Mixture, CFUgranulocyte/macrophage and BFU-E). A poor adherent cell layer, consisting almost exclusively of macrophages, was developed in UCB D-LTC and this correlated with a continuous decline in HPC numbers throughout the culture period. In contrast, adherent cell numbers in BM D-LTC, including fibroblasts and macrophages, were two-to fourfold higher than in UCB cultures, and the numbers of HPCs were also significantly higher, reaching plateau levels between weeks 6 and 9. In both types of cultures, erythroid and multipotent progenitors declined relatively fast, reaching undetectable levels after five weeks of culture. Myeloid progenitors, on the other hand, were sustained longer (always at higher levels in BM cultures) and were still detected by week 9. Among myeloid progenitors, a shift towards the predominance of macrophage HPCs was observed, both in UCB and BM D-LTC, and this correlated with an increase in the proportion of mature monocytes and macrophages. Taken together, our results indicate that myeloid progenitor cell growth is deficient in UCB D-LTC and suggest that this is due to the impaired development of an adherent cell layer, unable to provide the factors and conditions required for their growth. Interestingly, throughout the culture period the total numbers of multipotent and erythroid progenitors were similar both in UCB and BM cultures regardless of the number and types of adherent cells present; this suggests that the stroma developed in D-LTC is not sufficient for the proliferation of these progenitor cells.

The results obtained during this initial period are encouraging and indicate that the UCB banking and transplantation program at IMSS will help to improve already existing hematopoietic cell transplant programs in Mexico. The experience generated at IMSS may be helpful to other institutions, particularly those in developing countries.

No abstract

In the present study, we have assessed, in a comparative manner, the in vitro proliferation and expansion potentials of hematopoietic progenitor cells (HPC) present in mobilized peripheral blood from normal subjects (MPB-n; n = 18) and cancer patients (MPB-c; n = 18). The latter included patients with breast cancer (BrCa; n = 8), Hodgkin disease (HD; n = 4), non-Hodgkin lymphoma (NHL; n = 3), and acute myeloid leukemia (AML; n = 3). Progenitor cells from normal bone marrow (BM) and umbilical cord blood (UCB) were included as controls. HPC, enriched by a negative selection procedure, were cultured for 25 days, in serum-free liquid media in the presence of a cytokine combination including early- and late-acting cytokines. Our results demonstrate that the in vitro biological properties of progenitor cells present in MPB differ, depending on whether they are derived from healthy individuals, from patients with solid tumors, or from patients with hematological neoplasias. Among all cell sources analyzed, UCB-derived progenitors showed the greatest proliferation and expansion potentials (1000-fold increase in total cell numbers on day 15, and a 22-fold increase in myeloid progenitor cell numbers, at day 10). Progenitor cells present in MPB from hematologically normal individuals showed proliferation and expansion potentials comparable to those of HPC from normal BM (500-fold increase in total cell numbers on day 15, and a 14-fold increase in myeloid progenitor cell numbers, at day 10). The proliferation/expansion potentials of MPB progenitors from BrCa patients were also within the normal range, although in the lower levels (327-fold increase in total cell numbers, on day 15, and 11.8-fold increase in myeloid progenitors, at day 10). In contrast, progenitors present in MPB from patients with HD, NHL, and especially AML, showed reduced in vitro capacities (119-, 102-, and 51-fold increase in total cell numbers, respectively; and 8-, 4-, and 2.6-fold increase in myeloid progenitor cells, respectively). To our knowledge, this is the first report in which the in vitro proliferation and expansion potentials of HPC from MPB from normal subjects and cancer patients are assessed simultaneously in a comparative manner.

Although the experience presented herein is still limited and the period of analysis is still short, the results obtained during these 5 years are encouraging.