Bone remodeling alterations in myelodysplastic syndrome

There is a close relationship between hematopoietic bone marrow and bone cells. Thus, the profound derangement of hematopoiesis in myelodysplastic syndromes (MDS) might be expected to affect bone cell function. We studied the dynamic histomorphometric changes in bone in 22 MDS patients to examine this relationship and analyze the influence of hematological disease on bone remodeling. Bone-regulating hormones and histomorphometry of undecalcified transiliac bone biopsies, after double tetracycline labeling, were studied. Serum calcium, phosphorus, creatinine, alkaline phophatase, osteocalcin, iPTH, 25(OH)D₃, 1,25(OH)₂D₃, hydroxyprolinuria, and calcium/creatinine ratio in urine were normal compared with controls. Histomorphometry showed a significant decrease in osteoblast surface (Ob.S/BS) (0.30 ± 0.40 vs. 0.8 ± 1.1, p = 0.031), wall thickness (W.Th), (22.03 ± 5.5 vs. 31.8 ± 5.8, p <0.005), osteoclast number (N.Oc/T.Ar) (0.004 c 0.01 vs. 0.017 ± 0.01, p = 0.03), mineral apposition rate (MAR) (0.16 ± 0.15 vs. 0.53 ± 0.19, p <0.005), bone formation rate, surface referent (BFR/BS) (0.004 ± 0.10 vs. 0.016 ± 0.016, p = 0.009), and activation frequency (Ac.f) (0.06 ± 0.07 vs. 0.21 ± 0.23, p = 0.008). An increase in mineralization lag time (MLT) (119.2 ± 78.6 vs. 29.6 ± 77, p <0.005), (mean ± SD, unpaired Student t-test) was observed. Bone volume (BV/TV), eroded surfaces (ES/BS), and osteoid thickness (O.Th) remained unchanged. This picture of adynamic bone with decreased mineral apposition rate and markedly decreased osteoclast number is a characteristic finding in MDS patients. Thus, bone histomorphometric findings in MDS patients show the relationships and interactions between hematopoietic and bone cells.