Differentiation of bone marrow cells from myelodysplastic patients in the presence of 1,25 dihydroxyvitamin D3 or 13-cis retinoic acid

Regulation of monocyte differentiation by specific signaling modules and associated transcription factor networks

Monocyte/macrophages are important players in orchestrating the immune response as well as connecting innate and adaptive immunity. Myelopoiesis and monopoiesis are characterized by the interplay between expansion of stem/progenitor cells and progression towards further developed (myelo)monocytic phenotypes. In response to a variety of differentiation-inducing stimuli, various prominent signaling pathways are activated. Subsequently, specific transcription factors are induced, regulating cell proliferation and maturation. This review article focuses on the integration of signaling modules and transcriptional networks involved in the determination of monocytic differentiation.

Myelodysplasia and bone marrow fibrosis treated with calcitriol and venesection

We report a patient with myelodysplasia and bone marrow fibrosis. We managed him with regular blood transfusion for a period of 16 months. A modest dose of calcitriol (1,25-dihydroxycholecalciferol) 0.75 microg daily for 12 weeks resulted in a gradual but complete response in his haemoglobin level. There were significant bone marrow changes in that the fibrosis has completely disappeared although the marrow cytology remained dysplastic. The normal haemoglobin level persists despite an intensive venesection programme aimed at reducing iron overload. We conclude that calcitriol should be given for at least 12 weeks in patients with myelodysplasia especially if there is a fibrotic element in the bone marrow. The role of venesection in maintaining remission is a speculative.

All trans retinoic acid with low dose cytosine arabinoside in the treatment of myelodysplastic syndrome

The demonstration of synergistic interaction between differentiation inducing agents and DNA synthesis inhibitors suggests that these two groups act by two different mechanisms. We prospectively studied the response rate, response duration, survival, and toxicity in 10 patients with myelodysplastic syndrome (MDS) treated with all trans retinoic acid (ATRA) and low dose cytosine arabinoside (ara-C). These patients diagnosed between October 1993 and May 1995 were treated with ATRA (45 mg/M2/day) for 90 days followed by 90 mg/M2 on alternate day till Day 275; together with Ara-C (10 mg/m2) subcutaneously twice daily for 21 days for a total of 6 cycles. These patients were analyzed for response after 3 cycles of LD Ara-C and at the time of completion of therapy. Toxicity was recorded at the end of each cycle of Ara-C. There were 6 male and 4 female patients in the age range of 24 to 76 years. The morphological diagnosis was chronic myelomonocytic leukemia in 2, refractory anemia with excess blasts in 4 and refractory anemia with excess blasts in transformation in 4. Only 1 patient achieved a complete remission and 1 patient achieved a partial response. Four patients had progressive disease on treatment. One patient died of neutropenic sepsis and 1 of resistant thrombocytopenia and intracranial hemorrhage while on treatment. One patient refused further treatment after a minor clinical response and in 1 patient treatment was stopped due to toxicity. This data in a pilot study with a limited number of patient suggests that ATRA in combination with Ara-C has little effect in MDS.

New uses for old vitamins. The treatment of myelodysplastic disorders

The treatment of myelodysplastic disorders with vitamins A and D or derivatives and nutrients has been less than satisfactory. Combinations of vitamin D3 and 13-CRA with or without cytosine arabinoside appear to offer no advantage over any of the single agents alone. Until other vitamin D derivatives are developed that are effective but do not cause hypercalcemia, vitamin D3 cannot be recommended for the treatment of MDS. 13-CRA has been shown to be effective in some patients with MDS; however, it cannot be recommended as standard therapy because of the conflicting data cited above. Further clinical trials with 13-CRA perhaps in combination with vitamin E or colony-stimulating factors are clearly indicated for this disease for which we have no effective therapy.

In vitro suspension culture reactions to 1,25 dihydroxyvitamin D3 in relation to bone marrow morphology and prognosis in patients with myelodysplastic syndromes

Thirty-four patients with MDS or AML following MDS were studied with regard to survival, peripheral blood values and bone marrow morphology. The effects of 1,25 dihydroxyvitamin D3 (D3) on differentiation (NBT positivity) and proliferation (3H-thymidine incorporation) were studied in suspension cultures of bone marrow cells. Twelve bone marrow donors served as controls. Normal cells showed spontaneous differentiation in vitro, but only 2/12 were induced to differentiation by D3. Myelodysplastic cells did not differentiate spontaneously, but cells from 18/34 patients differentiated after incubation with D3. Normal cells showed increased proliferation, myelodysplastic cells showed a heterogeneous response and leukemic cells reacted with decreased proliferation after D3 incubation. Poor survival was associated with low platelet counts, high percentage of bone marrow blasts (BM blast %), low spontaneous in vitro proliferation and absence of hypogranulation of myeloid cells. Platelet counts and hypogranulation retained their predictive value in a multi-variate analysis. Progression to AML was predicted by a high BM blast % and low scores for erythroid and total dysplasia. In conclusion, the pattern of in vitro proliferation showed prognostic value while the pattern of vitamin D3-induced differentiation failed to correlate to other parameters. An estimation of bone marrow dysplasia can be used to predict the development of AML. Our results add to the information about the biology of MDS and may be important for the evaluation of therapeutic trials.

Therapeutic aspects of myelodysplastic syndromes in chronic phase

Myelodysplastic syndromes (MDS) include hemopoietic cytopenias of different origin, which are usually refractory to treatment. Therefore MDS patients should generally be treated conservatively. Transfusions of packed red cells (given in a strict regimen to minimize the risk for secondary hemochromatosis) may be sufficient to maintain a good quality of life. Indications for cytotoxic treatment include signs of progression of the disease. In patients with symptomatic cytopenias low-dose cytarabine (ara-C) should be tried. It is essential then to monitor each patient individually and to avoid fixed treatment schedules. Standard (high-dose) chemotherapy in MDS, is associated with a high mortality and a low response rate, and should be considered only in younger patients with advanced MDS. Allogeneic bone marrow transplantation (BMT) may be offered to younger MDS patients, when a suitable donor is available. Treatment with differentiation inducers has not met with expectations and should not be used outside clinical trials at the present. The use of recombinant hemopoietic growth factors (GF) seems promising. GF, like GM-CSF, G-CSF, IL-3, and erythropoietin, can be used either alone or in combinations, to support failing peripheral blood values, and decrease the risk for lethal complications. GF can also be given together with chemotherapy, in an effort to make the leukemic clonogenic cells more susceptible to cytotoxic drugs. Other treatments for MDS include: IFN-alpha and etoposide, with responses primarily in chronic myelomonocytic leukemia; hem arginate, whose role is still not clear; and corticosteroids, but only in carefully selected cases.

Treatment of myelodysplastic syndromes with retinoic acid and 1 alpha-hydroxy-vitamin D3 in combination with low-dose ara-C is not superior to ara-C alone. Results from a randomized study. The Scandinavian Myelodysplasia Group (SMG)

63 evaluable patients with myelodysplastic syndromes (MDS) and 15 with acute myelogenous leukemia (AML) were randomized between low-dose ara-C (arm A) and low dose ara-C in combination with 13-cis-retinoic acid (13-CRA) and 1 alpha-hydroxy-vitamin D3 (1 alpha D3) (arm B). 69 patients were evaluable and 18 (26.1%) responded to therapy. The addition of 13-CRA and 1 alpha D3 had no positive influence on survival of the patients, remission rates or duration of remissions. 12/27 patients in arm A and 6/29 patients in arm B progressed from MDS to AML during the course of the study (p = 0.0527). Arm B gave significantly more side-effects than arm A (p = 0.005). Therapeutic effects of 13-CRA and 1 alpha D3 on MDS is not supported by this study. However, an inhibiting effect on AML development in some MDS subgroups cannot be excluded.

Cooperative effects of gamma-interferon and 1 alpha, 25-dihydroxyvitamin D3 on in vitro differentiation of the blast cells of RAEB and RAEB-T

We added recombinant human gamma-interferon (gamma-IFN) and 1 alpha, 25-dihydroxyvitamin D3 (1 alpha, 25 (OH)2D3) to the bone marrow cells from six patients with RAEB or RAEB-T in liquid suspension cultures. After cultivation for 7 to 9 days, numerical, morphological and functional changes of the cells were assessed. gamma-IFN and 1 alpha, 25 (OH)2D3 additively suppressed cell growth, especially the number of blast cells decreased. The expression of alpha-naphthylbutyrate esterase (NBE) activity appeared to be promoted but that of naphthol AS-D chloroacetate esterase (NAE) activity was apparently suppressed by the addition of gamma-IFN and/or 1 alpha, 25 (OH)2D3. The percentage of NBT reduction-positive cells and latex-phagocytizing cells was only slightly increased by both agents. These results indicate that gamma-IFN and 1 alpha, 25 (OH)2D3 cooperate to induce monocytoid differentiation of the patients' blast cells. Combination therapy with both agents merits further study.

Effects of recombinant G-CSF and GM-CSF on in vitro differentiation of the blast cells of RAEB and RAEB-T

To evaluate the effects of recombinant G-CSF and GM-CSF on RAEB and RAEB-T cells, blast cells from 6 patients were incubated in liquid culture systems with these CSFs for 7 days, and their numerical, morphological and functional changes were assessed. Both CSFs stimulated cell growth, but decreased the proportion of blast cells in 5 of the 6 cases. Karyotypic abnormalities persisted during cultivation in some cases. The CSFs also stimulated the expression of part of the esterase activities, and a positive interaction of both CSFs was seen in part. Although CSFs had no significant effects on the ability of cells to reduce NBT or to phagocytize latex particles, the results indicated that they induce partial differentiation of blast cells. It appears that such pathological cells still retain the capacity to respond to growth factors.

Effect of vitamin D deficiency on macrophage and lymphocyte function in the rat

Vitamin D deficiency has pronounced growth retardation effects on the skeletal system. Because the immune system has been implicated in the regulation of bone metabolism, we examined the effect of vitamin D deficiency on the functional development of immune function in a rachitic rat model. Rats deprived of vitamin D3 both in utero and in postnatal life (-/-) had significantly reduced thymocyte or splenocyte [3H]-thymidine incorporation to mitogens and decreased macrophage chemotaxis when compared with vitamin D3-sufficient rats (+/+). Rats that were deficient in vitamin D3 only during in utero development (-/+) or during postnatal life (+/-) tended to have [3H]thymidine incorporation levels that were intermediate to those of the -/- and +/+ group. Similarly, the chemotactic response of macrophages from the +/- and -/+ groups was intermediate to that of the -/- and +/+ group, except at high concentrations of C5a in which there was an overlap with the +/+ group. Interestingly, secretion of soluble mediators, including interleukin 2 by lymphocytes and interleukin 1 and PGE2 by macrophages, was unaffected by vitamin D deficiency. These results suggest that vitamin D3 is essential for the normal development of certain biological responses of lymphocytes and macrophages. Moreover, this rachitic rat model system will enable further evaluation of the role of vitamin D in the functional development of the cells of the immune system and their relationship to skeletal growth.

Effects of retinoic acid, 1,25-dihydroxyvitamin D3, cytosine arabinoside and alpha-interferon on bone marrow cells from patients with myelodysplastic syndromes

Bone marrow cells from 15 patients with myelodysplastic syndromes and 2 with acute myeloid leukemia were incubated in vitro with all-trans-retinoic acid (RA), 1,25-dihydroxy vitamin D3 (D3), cytosine arabinoside (ara-C) and alpha-interferon (IFN). 3H-thymidine incorporation (3H-TdR), differentiation and clonal growth were studied. D3 was found to be the most effective inducer of differentiation and differentiation was correlated with a decreased 3H-TdR. Differentiation with one of the inducers was significantly correlated to differentiation with any of the other inducers. Patterns of differentiation and spontaneous and D3-induced 3H-TdR were used to divide the patients into 3 different groups. In the first group, 5 patients with extremely low spontaneous 3H-TdR and differentiation in combination with a slightly increased 3H-TdR after induction differed from all other patients by a higher percentage of bone marrow blast and a more pronounced pancytopenia. The two other groups had a high spontaneous 3H-TdR but differed with respect to the D3-induced differentiation which was absent in one group (n = 6) and present in the other (n = 5). The two groups showed no difference in the clinical features.

Differentiation induction therapy of myelodysplastic syndromes

Myelodysplastic syndromes are a heterogenous group of haemopoietic stem cell disorders characterized by dysplastic haematopoiesis and a defective maturation of a slowly expanding or sometimes of a stable population of haemopoietic progenitors. Defective maturation, which may involve one or more of the marrow cell lineages is regarded as the central pathophysiological feature of myelodysplastic syndromes. Patients with myelodysplastic syndromes respond poorly to conventional cytotoxic chemotherapy, frequently developing a prolonged marrow aplasia. The alternative and more appropriate form of therapy is differentiation induction therapy. The results of few preliminary clinical studies in myelodysplastic patients showed that a combination of differentiating agents is superior to single agent differentiation therapy. An extensive pre-clinical screening of the response of fresh cells from myelodysplastic patients in primary culture is needed to establish the optimal doses and conditions for significant synergies between various differentiating agents followed by large controlled randomized clinical trials based on differentiation induction therapy for patients with myelodysplastic syndromes.

Therapeutic effects of low-dose cytosine arabinoside, alpha-interferon, 1 alpha-hydroxyvitamin D3 and retinoic acid in acute leukemia and myelodysplastic syndromes

62 evaluable patients with myelodysplastic syndromes (MDS) or acute leukemia were treated with different combinations of low dose ara-C, alpha-interferon (IFN), 1 alpha-hydroxyvitamin D3 (vit D3) and retinoic acid. The aim was to study the efficacy and toxicity of each combination. The overall rate was 44%. Of these, 50% responded favorably to the combination of IFN, vit D3 and retinoic acid (IDR), which was comparable to the response rate of 43% for low-dose ara-C. The results of the IDR treatment may be explained by additive or synergistic effects between the separate drugs in the combination. Ara-C and IDR treatment was generally well-tolerated but interferon gave more side effects than any other drug used in the study. Evaluation of the full combination of ara-C, IFN, vit D3 and retinoic acid was not possible because of toxicity. Marrow hypoplasia was infrequent (5/27 patients) in cases responding favorably to treatment. Complete remissions were not longer than partial remissions or significant responses.

Biology of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) represent a diverse spectrum of disorders ranging from refractory anemia to a preleukemic state. Peripheral cytopenias, cellular marrow, dysplasias and dysfunctions of myeloid and lymphoid cells constitute hematological hallmarks, and are caused by ineffective hemopoiesis. Investigations of cell cultures and cellular functions indicate that the disease originates in a stem cell pluripotent to all myeloid cells and possibly lymphoid cells as well. The disease commonly runs a chronic indolent course, often terminating in acute leukemia or nonleukemic death, notably infections and/or hemorrhage due to cytopenias and cellular dysfunctions. Clonal expansion or clonal evolution appears to be related to the disease progression with a greater degree of malignancy. However, the initial sequence of events causing damage to stem cells is still undefined.