Objectives Basic calcium phosphate (BCP) crystals contribute to several syndromes associated with tendon disease, including acute calcific tendinitis and Milwaukee Shoulder Syndrome. Interactions between BCP crystals and tenocytes (tendon cells) may contribute to these clinical syndromes. This study aimed to determine the direct effects of BCP crystals on tenocyte function and viability. Methods In vitro assays were used to assess changes in human tenocytes cultured with BCP crystals. Real-time PCR was used to determine changes in the expression of tendon-related genes and extracellular matrix remodelling enzymes (metalloproteinases, MMPs; a disintegrin and metalloproteases, ADAMTS; and tissue inhibitor of metalloproteinases, TIMPs). ELISA was used to measure protein concentrations in tenocyte supernatants. MTT and alamarBlue™ assays were used to determine changes in cell viability. Results BCP crystals upregulated tenocyte gene expression of MMP-1, MMP-3, ADAMTS-4 and TIMP-1 after 24 h. Time course experiments showed expression peaked at 8 h for TIMP-1 and 48 h for MMP-1 and ADAMTS-4. Cyclooxygenase (COX)-1 gene expression was upregulated after 48 h. Tenocytes did not alter expression of scleraxis and tendon collagens, and expression of pro-inflammatory cytokines was not induced with BCP crystals. BCP crystals increased tenocyte release of prostaglandin E2 (PGE2) and MMP-1 protein after 24 h. However, neither COX-1 inhibition nor COX-2 inhibition led to consistent change in BCP crystal -induced tenocyte gene expression of extracellular matrix remodelling enzymes. BCP crystals had no effect on tenocyte viability. Conclusion BCP crystals induce extracellular matrix remodelling enzymes, but not inflammatory cytokines, in tenocytes.

中文翻译：

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碱性磷酸钙晶体诱导肌腱细胞表达细胞外基质重塑酶

目的 碱性磷酸钙 (BCP) 晶体会导致多种与肌腱疾病相关的综合征，包括急性钙化性肌腱炎和密尔沃基肩综合征。BCP 晶体和肌腱细胞（肌腱细胞）之间的相互作用可能导致这些临床综合征。本研究旨在确定 BCP 晶体对肌腱细胞功能和活力的直接影响。方法 体外试验用于评估用 BCP 晶体培养的人肌腱细胞的变化。实时 PCR 用于确定肌腱相关基因和细胞外基质重塑酶（金属蛋白酶，MMP；解整合素和金属蛋白酶，ADAMTS；以及金属蛋白酶组织抑制剂，TIMP）表达的变化。ELISA 用于测量肌腱细胞上清液中的蛋白质浓度。MTT 和 alamarBlue™ 测定用于确定细胞活力的变化。结果BCP晶体在24小时后上调MMP-1、MMP-3、ADAMTS-4和TIMP-1的肌腱细胞基因表达。时程实验表明，TIMP-1 的表达在 8 小时达到峰值，MMP-1 和 ADAMTS-4 的表达在 48 小时达到峰值。环氧合酶 (COX)-1 基因表达在 48 小时后上调。肌腱细胞不会改变巩膜和肌腱胶原蛋白的表达，并且 BCP 晶体不会诱导促炎细胞因子的表达。BCP 晶体在 24 小时后增加了前列腺素 E2 (PGE2) 和 MMP-1 蛋白的肌腱细胞释放。然而，COX-1 抑制和 COX-2 抑制均未导致 BCP 晶体诱导的细胞外基质重塑酶的肌腱细胞基因表达的一致变化。BCP 晶体对肌腱细胞活力没有影响。