Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany.
Osteoporos Int. 2011 Oct;22(10):2667-75. doi: 10.1007/s00198-011-1528-y. Epub 2011 Jan 26.
Histomorphometry and quantitative backscattered electron microscopy of iliac crest biopsies from patients with adult hypophosphatasia not only confirmed the expected enrichment of non-mineralized osteoid, but also demonstrated an altered trabecular microarchitecture, an increased number of osteoblasts, and an impaired calcium distribution within the mineralized bone matrix.
Adult hypophosphatasia is an inherited disorder of bone metabolism caused by inactivating mutations of the ALPL gene, encoding tissue non-specific alkaline phosphatase. While it is commonly accepted that the increased fracture risk of the patients is the consequence of osteomalacia, there are only few studies describing a complete histomorphometric analysis of bone biopsies from affected individuals. Therefore, we analyzed iliac crest biopsies from eight patients and set them in direct comparison to biopsies from healthy donors or from individuals with other types of osteomalacia.
Histomorphometric analysis was performed on non-decalcified sections stained either after von Kossa/van Gieson or with toluidine blue. Bone mineral density distribution was quantified by backscattered electron microscopy.
Besides the well-documented enrichment of non-mineralized bone matrix in individuals suffering from adult hypophosphatasia, our histomorphometric analysis revealed alterations of the trabecular microarchitecture and an increased number of osteoblasts compared to healthy controls or to individuals with other types of osteomalacia. Moreover, the analysis of the mineralized bone matrix revealed significantly decreased calcium content in patients with adult hypophosphatasia.
Taken together, our data show that adult hypophosphatasia does not solely result in an enrichment of osteoid, but also in a considerable degradation of bone quality, which might contribute to the increased fracture risk of the affected individuals.
对成人低磷酸酯酶症患者的髂嵴活检进行组织形态计量学和定量背散射电子显微镜检查，不仅证实了非矿化类骨质的预期富集，还显示出小梁微结构改变、成骨细胞数量增加以及矿化骨基质内钙分布受损。
成人低磷酸酯酶症是一种遗传性骨代谢疾病，由编码组织非特异性碱性磷酸酶的 ALPL 基因突变引起。虽然普遍认为患者的骨折风险增加是骨软化症的结果，但仅有少数研究描述了受影响个体的骨活检的完整组织形态计量学分析。因此，我们分析了 8 例患者的髂嵴活检，并将其与健康供体或其他类型骨软化症患者的活检进行直接比较。
对经 von Kossa/van Gieson 或甲苯胺蓝染色的未脱钙切片进行组织形态计量学分析。通过背散射电子显微镜对骨矿物质密度分布进行定量。
除了在成人低磷酸酯酶症患者中已经充分证明的非矿化骨基质的富集外，我们的组织形态计量学分析还显示出与健康对照组或其他类型骨软化症患者相比，小梁微结构的改变和成骨细胞数量的增加。此外，对矿化骨基质的分析显示，成人低磷酸酯酶症患者的钙含量明显降低。
综上所述，我们的数据表明，成人低磷酸酯酶症不仅导致类骨质的富集，还导致骨质量的明显下降，这可能导致受影响个体的骨折风险增加。
