As osteogenesis is a multifactorial mechanism, we wonder whether osteoblast-induced extracellular matrix (ECM) remodeling might be modulated by trophic factors released by fibroblasts in a paracrine signaling manner. To address this issue, fibroblasts were cultured for 72 h under conventional conditions when their conditioned medium was harvested and used to challenge pre-osteoblasts (MC3T3-E1 cells) for 14 days. Preliminarily, we validated the potential effect of fibroblasts in contributing to osteocyte phenotype, which specifically requires significant expression of Dentin Matrix Protein 1 (DMP1; about 10-fold changes) and Sclerostin (SOST; about 7-fold changes), both biomarkers of osteocyte. Fibroblasts also seem contributing to ECM remodeling in osteoblasts, because we detected a high level of both mRNA and enzyme activities of matrix metalloproteinase -9 (MMP-9) as well as a high level of reversion inducing cysteine rich protein with kazal motifs (RECK) transcripts (about 13-fold changes), a membrane-anchored MMP inhibitor, which seems to be a constitutive pathway in osteoblasts. Considering inflammatory panorama and using RTqPCR technology, both IL-13 (about 13-fold changes) and IL-33 (about 5-fold changes) genes were up-expressed in response to the fibroblast-secreted trophic factors, as were the receptor activator of NF-κB ligand (RANKL; about 8-fold changes) and osteoprotegerin (OPG; about 3-fold changes). Although preliminary, these data suggest a stimulus to finely control osteoclastogenesis, and this mechanism reinforces the role of fibroblasts in bone remodeling and homeostasis. Moreover, these results suggest an important crosstalk between fibroblast and osteoblast, when fibroblast-secreted trophic factors upmodulate osteocyte gene markers and contribute to ECM remodeling stimulus in osteoblast.

中文翻译：

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成纤维细胞分泌的营养因子有助于ECM重塑刺激并上调成骨细胞中的骨细胞基因标记。

由于成骨是一个多因素机制，我们想知道成骨细胞诱导的细胞外基质（ECM）重塑是否可能由成纤维细胞以旁分泌信号方式释放的营养因子调节。为解决此问题，当收获成纤维细胞的条件培养基并在常规条件下培养72小时，并用于挑战成骨细胞（MC3T3-E1细胞）14天。初步，我们验证了成纤维细胞对骨细胞表型的潜在影响，这特别需要显着表达牙本质基质蛋白1（DMP1；大约10倍变化）和硬化蛋白（SOST；大约7倍变化），这两个都是骨细胞的生物标志物。 。成纤维细胞似乎也有助于成骨细胞的ECM重塑，因为我们检测到基质金属蛋白酶-9（MMP-9）的mRNA和酶活性都很高，并且还检测到了高水平的诱导还原的带有kazal模体（RECK）转录本的富含半胱氨酸的蛋白（约13倍变化），膜锚定的MMP抑制剂，这似乎是成骨细胞的组成性途径。考虑到炎症全景并使用RTqPCR技术，响应成纤维细胞分泌的营养因子，IL-13（约13倍变化）和IL-33（约5倍变化）基因均被高表达，受体激活剂也被表达NF-κB配体（RANKL；大约8倍变化）和骨保护素（OPG；大约3倍变化）。尽管是初步的，但这些数据表明可以精确控制破骨细胞的刺激，并且这种机制增强了成纤维细胞在骨骼重塑和体内平衡中的作用。而且，