Tissue-engineered replacement discs are an area of intense investigation for the treatment of end-stage intervertebral disc (IVD) degeneration. These living implants can integrate into the IVD space and recapitulate native motion segment function. We recently developed a multiphasic tissue-engineered disc-like angle-ply structure (DAPS) that models the micro-architectural and functional features of native tissue. While these implants resulted in functional restoration of the motion segment in rat and caprine models, we also noted deficiencies in cell infiltration and homogeneity of matrix deposition in the electrospun poly(ε-caprolactone) outer region (annulus fibrosus, AF) of the DAPS. To address this limitation, here, we incorporated a sacrificial water-soluble polymer, polyethylene oxide (PEO), as a second fiber fraction within the AF region to increase porosity of the implant. Maturation of these PEO-modified DAPS were evaluated after 5 and 10 weeks of in vitro culture in terms of AF biochemical content, MRI T2 values, overall construct mechanical properties, AF micromechanical properties and cell and matrix distribution. To assess the performance of the PEO-modified DAPS in vivo, precultured constructs were implanted into the rat caudal IVD space for 10 weeks. Results showed that matrix distribution was more homogenous in PCL/PEO DAPS, as evidenced by more robust histological staining, organized collagen deposition and micromechanical properties, compared to standard PCL-only DAPS in vitro. Cell and matrix infiltration were also improved in vivo, but no differences in macromechanical properties and a trend towards improved micromechanical properties were observed. These findings demonstrate that the inclusion of a sacrificial PEO fiber fraction in the DAPS AF region improves cellular colonization, matrix elaboration, and in vitro and in vivo function of an engineered IVD implant.

Statement of significance

This work establishes a method for improving cell infiltration and matrix distribution within tissue-engineered dense fibrous scaffolds for intervertebral disc replacement. Tissue-engineered whole disc replacements are an attractive alternative to the current gold standard (mechanical disc arthroplasty or vertebral fusion) for the clinical treatment of patients with advanced disc degeneration.

中文翻译：

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牺牲纤维改善了组织工程化椎间盘的基质分布和微机械性能。

组织工程化的置换椎间盘是治疗终末期椎间盘退变（IVD）的一个深入研究领域。这些活体植入物可以整合到IVD空间中，并概括天然运动节段的功能。我们最近开发了一种多相组织工程化的盘状角铺层结构（DAPS），该结构可模拟天然组织的微结构和功能特征。虽然这些植入物在大鼠和山羊模型中导致运动节段的功能恢复，但我们还注意到DAPS电纺聚（ε-己内酯）外部区域（纤维环，AF）中细胞浸润和基质沉积均匀性不足。为了解决这一局限性，我们在此处加入了一种牺牲水溶性聚合物聚环氧乙烷（PEO），作为第二纤维部分在AF区域内，以增加植入物的孔隙率。这些PEO修饰的DAPS的成熟度是在5周和10周的在体外培养中，AF的生化含量，MRI T2值，整体构建体的机械性能，AF的微机械性能以及细胞和基质的分布。为了评估PEO修饰的DAPS在体内的性能，将预培养的构建体植入大鼠尾静脉IVD空间10周。结果显示，与标准PCL-DAPS体外相比，PCL / PEO DAPS中的基质分布更均匀，这由更强健的组织学染色，有组织的胶原蛋白沉积和微机械特性证明。体内细胞和基质浸润也得到改善，但没有观察到宏观力学性能的差异以及改善的微观力学性能的趋势。这些发现表明，DAPS AF区域中包含牺牲性PEO纤维部分可改善细胞定植，基质修饰以及工程化IVD植入物的体外和体内功能。

重要声明

这项工作建立了一种方法，用于改善组织工程化的致密纤维支架中的细胞浸润和基质分布，以替代椎间盘。组织工程设计的全椎间盘置换术是目前用于临床治疗晚期椎间盘退变患者的金标准（机械椎间盘置换术或椎骨融合术）的一种有吸引力的替代方法。