Biomaterial and Tissue Engineering Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, India.
Department of Biomedical Engineering, Tufts University, Medford, MA 02155
Proc Natl Acad Sci U S A. 2018 Jan 16;115(3):477-482. doi: 10.1073/pnas.1715912115. Epub 2017 Dec 27.
Recapitulation of the form and function of complex tissue organization using appropriate biomaterials impacts success in tissue engineering endeavors. The annulus fibrosus (AF) represents a complex, multilamellar, hierarchical structure consisting of collagen, proteoglycans, and elastic fibers. To mimic the intricacy of AF anatomy, a silk protein-based multilayered, disc-like angle-ply construct was fabricated, consisting of concentric layers of lamellar sheets. Scanning electron microscopy and fluorescence image analysis revealed cross-aligned and lamellar characteristics of the construct, mimicking the native hierarchical architecture of the AF. Induction of secondary structure in the silk constructs was confirmed by infrared spectroscopy and X-ray diffraction. The constructs showed a compressive modulus of 499.18 ± 86.45 kPa. Constructs seeded with porcine AF cells and human mesenchymal stem cells (hMSCs) showed ∼2.2-fold and ∼1.7-fold increases in proliferation on day 14, respectively, compared with initial seeding. Biochemical analysis, histology, and immunohistochemistry results showed the deposition of AF-specific extracellular matrix (sulfated glycosaminoglycan and collagen type I), indicating a favorable environment for both cell types, which was further validated by the expression of AF tissue-specific genes. The constructs seeded with porcine AF cells showed ∼11-, ∼5.1-, and ∼6.7-fold increases in col I, sox 9, and aggrecan genes, respectively. The differentiation of hMSCs to AF-like tissue was evident from the enhanced expression of the AF-specific genes. Overall, the constructs supported cell proliferation, differentiation, and ECM deposition resulting in AF-like tissue features based on ECM deposition and morphology, indicating potential for future studies related to intervertebral disc replacement therapy.
使用适当的生物材料来概括复杂组织的形态和功能对组织工程的成功有重要影响。纤维环(AF)是一种复杂的、多层的、层次结构,由胶原蛋白、蛋白聚糖和弹性纤维组成。为了模拟 AF 解剖结构的复杂性,构建了一种基于丝蛋白的多层、盘状角层结构,由同心层的片状层组成。扫描电子显微镜和荧光图像分析显示了构建体的交叉排列和层状特征,模拟了 AF 的天然层次结构。红外光谱和 X 射线衍射证实了丝蛋白构建体中二级结构的诱导。构建体的压缩模量为 499.18±86.45kPa。与初始接种相比,接种猪 AF 细胞和人骨髓间充质干细胞(hMSCs)的构建体在第 14 天的增殖分别增加了约 2.2 倍和 1.7 倍。生物化学分析、组织学和免疫组织化学结果表明,构建体中沉积了 AF 特异性细胞外基质(硫酸化糖胺聚糖和 I 型胶原蛋白),表明这为两种细胞类型提供了有利的环境,这进一步通过 AF 组织特异性基因的表达得到了验证。接种猪 AF 细胞的构建体中 col I、sox9 和 aggrecan 基因的表达分别增加了约 11 倍、5.1 倍和 6.7 倍。hMSCs 向 AF 样组织的分化从 AF 特异性基因的增强表达中可见一斑。总的来说,这些构建体支持细胞增殖、分化和细胞外基质沉积,导致基于细胞外基质沉积和形态的 AF 样组织特征,表明其在未来与椎间盘置换治疗相关的研究中有潜在应用。