Evaluation of Bone Marrow Microvessel Density in Patients with Aplastic Anemia.

Bone marrow microenvironment plays a crucial role in the growth of hemopoietic cells and bone marrow function, which in turn depends on an intact microvasculature. Our study assesses the microvessel density (MVD) in the bone marrow of aplastic anemia (AA) patients, compares with MVD of controls and MVD among the different types of AA. Bone marrow specimens from 60 patients with AA and 17 controls were studied. There were 33 patients with non severe AA (NSAA), 12 patients with severe AA (SAA) and 15 patients with very severe AA (VSAA). MVD was calculated on sections stained immunohistochemically for CD34. The mean bone marrow MVD in AA group was 1.28 ± 0.36, being significantly lower than that in control group (6.80 ± 1.59,  < 0.001). MVD of SAA and NSAA patients were 1.16 ± 0.35 and 1.49 ± 0.27, respectively, being significantly different ( = 0.003). MVD of VSAA was 0.93 ± 0.25 and the difference with NSAA is significant, however there was no significant difference between SAA and VSAA. Bone marrow MVD is low in AA patients and is likely to have a role in pathophysiology of bone marrow failure. Proangiogenic agents together with specific therapy might accelerate the recovery of hematopoiesis in AA patients.