Even after several decades of research, the most optimal source of silk for promoting osteogenesis in situ is still a subject of debate. A major gap in existing knowledge is role of underlying signaling mechanisms in both the mulberry and nonmulberry silk species that leads to the development of differential levels of osteogenesis. In our previous study, we elucidated the role of Wnt/β-catenin signaling for promoting superior osteogenic differentiation in nonmulberry silk braids in the presence of TGF-β and pro-osteogenic supplements. Here, we provide a comparative osteogenic analysis of the two most popular silk species (mulberry and nonmulberry silk), in the form of silk braids prepared from natively spun fibers, by conducting detailed gene expression profiling using 25 different osteogenic markers, followed by further validation by immunohistochemistry. Our study provides novel insights into the direct regulatory role of nonmulberry silk fibroin braids on hedgehog and parathyroid signaling pathways in controlling osteogenic differentiation of cultured human fetal osteoblasts (hFOBs), a phenomenon not very evident in the mulberry silk textile braids. Although both silk braids enabled adequate cellular attachment, proliferation, and extracellular collagen matrix formation, superior expression of osteogenic markers (ALP, VDR, Runx2), matrix proteins (Col1A2, OPN), and signaling molecules (GLI1, GLI2, Shh) with characteristic terminal osteocytic phenotype could only be observed in nonmulberry silk. Therefore, our study provided detailed insights into the development of engineered bone to be a prospective tissue equivalent with potential to provide the essential instructive elements for activating physiological pathways of bone differentiation. Such engineered constructs have potential for use as an in vitro model for drug testing and as scaffolds for bone regeneration strategies.

中文翻译：

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桑蚕和非桑蚕丝素蛋白纺织辫子中刺猬和甲状旁腺信号的差异调节

即使经过几十年的研究，用于促进原位成骨的最佳丝源仍然是一个争论的话题。现有知识的主要差距是桑蚕和非桑蚕丝物种中潜在的信号传导机制所起的作用，这导致了不同水平的成骨作用的发展。在我们先前的研究中，我们阐明了在存在TGF-β和促成骨补剂的情况下，Wnt /β-catenin信号传导在促进桑蚕丝编织物中优异的成骨分化中的作用。在这里，我们通过使用25种不同的成骨标记物进行详细的基因表达谱分析，以天然纺丝纤维制成的辫子形式，对两种最流行的蚕种（桑蚕和非桑蚕丝）进行了比较的成骨分析，然后通过免疫组织化学进一步验证。我们的研究为非桑蚕丝丝蛋白编织物对刺猬和甲状旁腺信号通路在控制培养的人类胎儿成骨细胞（hFOB）的成骨分化中的直接调节作用方面提供了新颖的见解，这种现象在桑蚕丝织物编织物中并不十分明显。尽管两种丝质编织物都能实现足够的细胞附着，增殖和细胞外胶原基质形成，但成骨标记物（ALP，VDR，Runx2），基质蛋白（Col1A2，OPN）和信号分子（GLI1，GLI2，Shh）具有出色的表达能力终末骨细胞表型只能在非桑蚕丝中观察到。所以，我们的研究为工程骨的发展提供了详细的见解，使其成为具有前瞻性组织的潜力，并有潜力为激活骨分化的生理途径提供基本的指导性元素。这样的工程构建体具有用作药物测试的体外模型和骨再生策略的支架的潜力。