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Cell regulation of Ph+cell proliferation and differentiation has been studied ex vivo in various chronic myeloid leukemia (CML) patients. The regulation is provided by alternation of effective stages of proliferation and maturation with inhibition of Ph+ cell proliferation by accumulating neutrophils under apoptosis blockage. The alternation of stages consists of switching stage 1 (effective proliferation) to stage 2 (effective maturation) and proceeds according to the 1/2 -1/2/1 or 2/1-2/1/2/1 schemes. The kinetic plots of alternations pass through control points of crossing plots, where the parameters of proliferation and maturation are equal. The indices of P/D efficiency (ratio of proliferation and maturation rates) are 1.06±0.23 and don't depend on time, alternation order, or sources of Ph+ cells - CML patients. During stages alternation, conversely, the parameters of Ph+ cell proliferation and maturation vary. The proliferation stages are characterized by increased proliferating cells content, a decreased number of neutrophils, and apoptosis induction. At the maturation stages, conversely, apoptosis is inhibited, the number of mature neutrophils increases, while immature Ph+ cells decrease. High content neutrophils inhibit the proliferation of Ph+ cells and impair their own maturation by inversion of maturation order, probably through a feedback mechanism. The regulation differences ex vivo reveal three types of Ph+ cells from various individual CML patients, distinguished by the number and duration of alternating stages of proliferation and maturation. Ph+ cells types 1 and 2 have one prolonged stage of effective proliferation or effective maturation with efficiency indices P/D1 = 1-20 or P/D2 ⇐ 1. At the same time period, the proliferation and differentiation of the Ph+ cells type 3 proceeds with repeated alternations of stages with P/D1 = 1-4 or P/D2 ⇐ 1. Type 1 Ph+ cells (~20%) were isolated from patients in advanced stages of CML, while Ph+ cells types 2 and 3 (30 and 50% correspondingly) were isolated from CML chronic phase patients sensitive to chemotherapy.

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We studied the expression of VCAM-1 adhesion molecules on stromal cells from the bone marrow of patients with myelodysplastic syndromes, healthy donors, and patients with chronic myeloproliferative diseases and acute leukemias. Expression of adhesion molecule on mesenchymal stromal cells from the bone marrow of patients and healthy donors was evaluated after 2-4 passages by the methods of immunoprecipitation and electrophoresis. VCAM-1 expression in the majority of patients with myelodysplastic syndromes was lower than in healthy donors. At the same time, VCAM-1 expression was not identified on mesenchymal cells from acute leukemia patients. VCAM-1 expression on cells from patients with chronic myeloproliferative diseases did not differ from that in healthy donors. We conclude that VCAM-1 synthesis in bone marrow stromal cells is impaired in patients with myelodysplastic syndromes and acute leukemias. These changes can be followed by the loss of relationships between hemopoietic cells and stromal microenvironment in bone marrow niches. Hemopoietic cells gain the ability for uncontrolled growth, which results in progression of the disease.

We studied functional disturbances in hemopoietic microenvironment and cytokine production by stromal sublayer in long-term bone marrow cultures and peripheral blood macrophages from patients with various forms of myelodysplastic syndrome. Production of factors stimulating the growth of normal erythroid and granulocytic precursors by cells of the stromal sublayer from patients with refractory sideroblast anemia and refractory anemia with excess blasts is impaired compared to cells from healthy donors. The medium conditioned by macrophages from patients with chronic myelomonocytic leukemia displayed a higher ability to stimulate the growth of granulocytes and macrophages compared to media conditioned by cells from donors and patients with refractory sideroblast anemia and refractory anemia with excess blasts. Cultured stromal cells and macrophages produced tumor necrosis factor-alpha and interleukin-6. Their content in media conditioned by cells from patients with myelodysplastic syndrome surpassed that in healthy donors. Our results suggest that production of cytokines by stromal microenvironmental cells is impaired in patients with various forms of myelodysplastic syndrome.