Calcification of rachitic rat cartilage in vitro by extracellular matrix vesicles.
Calcification of rachitic rat cartilage in vitro by extracellular matrix vesicles.
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发表时间：
1975-05
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通讯作者：
H. Anderson;R. Cecil;S. Sajdera
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作者：
H. Anderson;R. Cecil;S. Sajdera
研究了佝偻病大鼠的生长板软骨，以评估细胞外基质囊泡钙化的作用，细胞外基质囊泡被认为参与结缔组织矿化的初始阶段。基质囊泡的浓度和它们在纵向隔膜内的分布被认为是正常的大鼠佝偻病喂养低维生素D和磷酸盐3周后断奶。佝偻病软骨基质中不含正常软骨的磷灰石环囊簇，然而，偶尔囊泡包围一个或几个磷灰石针。当将佝偻病软骨切片在亚稳磷酸钙溶液（[Ca++]乘以[PO SEE ARTICLE]等于3.5 mM，等于2）中于37 ℃下孵育时，磷灰石形成开始与基质囊泡结合。在这些条件下，矿化是突出的上部肥大软骨，其中基质囊泡成为结壳后，只有2至3小时的孵育磷灰石。通过将软骨预热至60 ℃ 30分钟来抑制泡状磷灰石的积累。测量佝偻病软骨片从亚稳态磷酸钙溶液中摄取的45 Ca也表明热抑制钙化。光镜放射自显影显示45Ca主要定位于纵隔基质中，证实了佝偻病软骨愈合中矿化的抑制部位。加热前佝偻病囊泡内磷灰石的存在和热对囊泡钙化的抑制表明囊泡钙化的活性、酶促和介导机制。
Growth plate cartilage from rachitic rats was studied to assess the role in calcification of extracellular matrix vesicles, which are thought to participate in the initial stage of mineralization of connective tissue. The concentration of matrix vesicles and their distribution within the longitudinal septa was found to be normal in rats made rachitic by feeding by a diet low in vitamin D and phosphate for 3 weeks after weaning. Rachitic cartilage matrix did not contain circumvesicular clusters of apatite as does normal cartilage; however, occasional vesicles did enclose one or a few apatite needles. When slices of rachitic cartilage were incubated at 37 C in a metastable calcium phosphate solution ([Ca++] times [PO SEE ARTICLE] equals 3.5 mM identical to 2), apatite formation was initiated in association with matrix vesicles. Under these conditions, mineralization was prominent in the upper hypertrophic cartilage, where matrix vesicles became encrusted with apatite after only 2 to 3 hours of incubation. Vesicular apatite accumulation was inhibited by preheating the cartilage to 60 C for 30 minutes. Measurements of 45Ca uptake by rachitic cartilage slices from metastable calcium phosphates solution also indicated inhibition of calcification by heat. Light microscopic autoradiographs showed 45Ca localization primarily in the matrix of longitudinal septa and substantiated the inhibition site of mineralization in healing rachitic cartilage. The presence of apatite within rachitic vesicles prior to heating and the inhibition of vesicle calcification by heat suggests an active, enzymatically and mediated mechanism of vesicular calcification.