Morphological changes and apoptosis in bone marrow from patients with myelodysplastic syndromes treated with...

A study of bone marrow morphology and apoptosis was undertaken in 51 patients with myelodysplastic syndromes (MDS) treated with granulocyte colony-stimulating factor (G-CSF) and erythropoietin (EPO). In 19 of these patients (37%), a significant improvement in the hemoglobin level was found after treatment. Apoptosis was measured using a nick-end labeling (TUNEL) technique. Patients with MDS had a significantly higher percentage of labelled (apoptotic) cells in the bone marrow compared to healthy individuals (56.3 +/- 3.8% vs. 16.2 +/- 1.4%, p = 0.0001). Patients with RAS showed a lower percentage of apoptotic cells than patients with RA (68.5 +/- 9% vs. 46.5 +/- 4.8%, p < 0.05), while patients with RAEB did not differ significantly from either RA or RAS. In the patients who responded to treatment, the bone marrow samples displayed significant morphological changes. The percentages of erythroid precursors and myeloblasts were reduced after treatment, and patients who had ring sideroblasts before treatment also showed a reduction in the percentage of these cells. Total erythroid index also decreased in responding patients. The percentage of apoptotic cells decreased significantly in responding patients (58.8 +/- 4.8% before treatment vs. 44.5 +/- 5.5% after treatment, mean reduction 18.3%, p = 0.0003), whereas no significant change was found in non-responding patients. Our results suggest that one important mechanism behind the positive effects of treatment with G-CSF and EPO is a reduction in the degree of ineffective hematopoiesis in MDS.