Deficient proliferation of myeloid, erythroid, and multipotent progenitor cells in long-term marrow cultures from patients with aplastic anemia treated with immunosuppressive therapy

Abstract

By using Dexter-type long-term marrow cultures (D-LTMC), it has been shown previously that hematopoietic progenitor cells (HPC) from patients with aplastic anemia (AA) have a deficient proliferation in vitro. The studies reported to date, however, have focused exclusively on granulomonocytic progenitors and no information exists on erythroid or multipotent progenitor cells. On the other hand, in such studies, the input progenitor cell numbers were significantly below normal levels, thus suggesting that the rapid disappearance of myeloid progenitor cells from AA D-LTMC could also be due, at least in part, to their reduced number at culture onset. In the present study, we have followed the kinetics of myeloid, erythroid, and multipotent progenitors, from 24 AA patients subjected to immunosuppressive therapy (including patients that achieved complete, partial, or no remission at all), throughout a seven-week culture period. For analysis, we grouped all the patients based on their initial content of all three types of progenitors. Thus, we were able to evaluate separately the kinetics of these cells in D-LTMC from patients with normal and subnormal levels of progenitor cells. At the time of marrow sampling, most patients showed decreased levels of HPC; in fact, only 21%, 8%, and 16% of them showed normal levels of myeloid, erythroid, and multipotent progenitors, respectively. When cultured in D-LTMC, HPC from all AA patients analyzed showed a relatively fast disappearance from the cultures. Indeed, myeloid progenitors could be detected for only six weeks, whereas erythroid and multipotent progenitors disappeared from the cultures after two and one weeks of culture, respectively. In contrast, in normal marrow D-LTMC, myeloid, erythroid, and multipotent progenitors were detected for at least seven, five, and three weeks, respectively. Such a deficient proliferation was observed even in cultures of AA patients that contained normal levels of HPC at culture onset. Interestingly, no correlation was found between HPC proliferation in D-LTMC and response to treatment. Thus, the results of this study indicate the presence of a functional in vitro deficiency in the hematopoietic system of patients with AA, including those that achieved partial or complete remission after immunosuppressive treatment. Furthermore, this work suggests that such a proliferation deficiency is more pronounced in erythroid and multipotent progenitors than in their myeloid counterparts.

Tumor necrosis factor‐α levels in long‐term marrow cultures from patients with aplastic anemia: modulation by granulocyte‐macrophage colony‐stimulating factor

“…The levels of myeloid, erythroid and multipotent progenitor cells in LTMC were followed throughout a 7-week culture period. The growth patterns observed were similar to those reported previously by us [7,10]. At all time points analyzed, CFC levels were signi®cantly higher (P < 0.05) in cultures from normal BM than in cultures from AA patients and by week 6 no CFC were detected in AA LTMC (Figure 1).…”

Matrix metalloproteinase and tissue inhibitors of metalloproteinase secretion by haematopoietic and stromal precursors and their production in normal and leukaemic long‐term marrow cultures

“…MMP-9 production increases while MMP-2 secretion decreases with time of culture. As MMP-2 is mainly produced by fibroblasts and endothelial cells, the decrease in MMP-2 secretion may be an indication that the stromal cell layer in AML LTMC is less well-established than normal LTMC, an observation made here and in previous studies Gomez-Morales et al, 1998;Zhang et al, 1999). The secretion of TIMP-1 and TIMP-2 reached an average maximal level of about 800 ng/ml in normal LTMC but was relatively constant at a lower concentration (500 ng/ml) in AML LTMC.…”

Evidence for a continuous decline in haemopoietic cell function from birth: application to evaluating bone marrow failure in children

“…However, the genes involved in the pathogeneses of Fanconi anaemia and dyskeratosis congenita are being characterized (D'Andrea & Grompe, 1997; Heiss et al , 1998) and candidate genes involved in the ageing of murine haemopoiesis have been identified (de Haan & van Zant, 1998a, b). Although it is well known that the numbers of haemopoietic progenitor cells are reduced in the blood and bone marrow of patients with bone marrow failure syndromes (Gomez‐Morales et al , 1998; Dirksen et al , 1998), our data show that qualitative defects in progenitor cells may exist as well.…”