Bone Histomorphometry Revisited

Bone histomorphometry is defined as a quantitative evaluation of bone micro architecture, remodelling and metabolism. Bone metabolic assessment is based on a dynamic process, which provides data on bone matrix formation rate by incorporating a tetracycline compound. In the static evaluation, samples are stained and a semi-automatic technique is applied in order to obtain bone microarchitectural parameters such as trabecular area, perimeter and width. These parameters are in 2D, but they can be extrapolated into 3D, applying a stereological formula. Histomorphometry can be applied to different areas; however, in recent decades it has been a relevant tool in monitoring the effect of drug administration in bone. The main challenge for the future will be the development of noninvasive methods that can give similar information. In the herein review paper we will discuss the general principles and main applications of bone histomorphometry.

Iron Overload in a Murine Model of Hereditary Hemochromatosis Is Associated with Accelerated Progression of Osteoarthritis Under Mechanical Stress

OBJECTIVE: Hereditary hemochromatosis (HH) is a disease caused by mutations in the Hfe gene characterised by systemic iron overload and associated with an increased prevalence of osteoarthritis (OA) but the role of iron overload in the development of OA is still undefined. To further understand the molecular mechanisms involved we have used a murine model of HH and studied the progression of experimental OA under mechanical stress. DESIGN: OA was surgically induced in the knee joints of 10-week-old C57BL6 (wild-type) mice and Hfe-KO mice. OA progression was assessed using histology, micro CT, gene expression and immunohistochemistry at 8 weeks after surgery. RESULTS: Hfe-KO mice showed a systemic iron overload and an increased iron accumulation in the knee synovial membrane following surgery. The histological OA score was significantly higher in the Hfe-KO mice at 8 weeks after surgery. Micro CT study of the proximal tibia revealed increased subchondral bone volume and increased trabecular thickness. Gene expression and immunohistochemical analysis showed a significant increase in the expression of matrix metallopeptidase 3 (MMP-3) in the joints of Hfe-KO mice compared with control mice at 8 weeks after surgery. CONCLUSIONS: HH was associated with an accelerated development of OA in mice. Our findings suggest that synovial iron overload has a definite role in the progression of HH-related OA