Dalle Carbonare L, Bertoldo F, Valenti M T, Zenari S, Zanatta M, Sella S, Giannini S, Cascio V Lo
Department of Biomedical and Surgical Sciences, Medicina Interna D, University of Verona, Italy.
Micron. 2005;36(7-8):645-52. doi: 10.1016/j.micron.2005.07.009. Epub 2005 Sep 2.
Bone histomorphometry or quantitative histology consists of counting or measuring tissue components: cells, extracellular constituents and microarchitecture. Bone histomorphometry is the only method that allows the measurement of mineralization rate and the study of bone formation at three levels: cell, remodeling unit and tissue levels. It is a useful tool to explain the pathogenesis and cellular mechanisms of different metabolic bone diseases such as glucocorticoid-induced osteoporosis (GIO). Glucocorticoids (GC) affect calcium and bone metabolism at every level, but the main effect is the osteoblastic dysfunction. Concerning the bone formation, some histomorphometric studies have shown a depressed osteoblastic activity at a cell, bone remodeling unit, and tissue levels. In addition, there is evidence of a shortening of the period in which the osteoblasts work actively forming the bone matrix. This latter effect seems to occur after high cumulative doses of GC. With regard to the resorption, the results are still debated, but histomorphometric parameters seem to be increased in the majority of studies, at least in the first period of the GC treatment. From a structural point of view, GC seem to induce a thinning of the trabeculae without their perforation, which occurs only after high cumulative doses. Anti-resorptive treatments, such as bisphosphonates, are able to counteract the negative effects of GC on bone. In particular, along with their active working period, they prolong the lifespan of osteoblasts and osteocytes. In addition, the anti-resorptive treatments seem to extend the time for secondary mineralization through a reduction of the Activation Frequency. The latter is an intriguing mechanism of bisphosphonates in GIO that needs further ad hoc investigations.
细胞、细胞外成分和微结构。骨组织形态计量学是唯一能够测量矿化速率并在细胞、重塑单位和组织三个层面研究骨形成的方法。它是解释不同代谢性骨病（如糖皮质激素诱导的骨质疏松症，GIO）发病机制和细胞机制的有用工具。糖皮质激素（GC）在各个层面影响钙和骨代谢，但主要作用是成骨细胞功能障碍。关于骨形成，一些组织形态计量学研究表明，在细胞、骨重塑单位和组织层面，成骨细胞活性降低。此外，有证据表明成骨细胞积极形成骨基质的活跃工作期缩短。后一种效应似乎在高累积剂量的GC作用后出现。关于骨吸收，结果仍存在争议，但在大多数研究中，至少在GC治疗的第一阶段，组织形态计量学参数似乎有所增加。从结构角度来看，GC似乎会导致小梁变薄但不会穿孔，只有在高累积剂量后才会穿孔。抗吸收治疗，如双膦酸盐，能够抵消GC对骨的负面影响。特别是，在其活跃工作期，它们延长了成骨细胞和骨细胞的寿命。此外，抗吸收治疗似乎通过降低激活频率来延长二次矿化的时间。后者是双膦酸盐在GIO中一种有趣的机制，需要进一步进行专门研究。
