A nanofiber-hydrogel composite plug for perianal fistula repair

总结 肛周瘘（PAF）发生在30-40%的克罗恩病患者中，其并发症导致 生活质量严重受损。目前的治疗方法在不到50%的病例中有效。整体 本研究的目的是开发一种生物刺激性纳米纤维-水凝胶复合材料（NHC）塞， 促进组织愈合，并在临床相关动物模型中测试其修复PAF的功效。以前的工作 来自Mao和Selaru实验室的研究为这项研究奠定了基础。具体来说，我们已经建立了新的啮齿动物 和PAF的猪模型，忠实地概括了患者中PAF的生物学。与此同时，我们开发了 第一代可注射生物降解纳米纤维-水凝胶复合材料（NHC），来自聚（e-己内酯）（PCL） 纳米纤维共价键合到透明质酸（HA）水凝胶;并证明其能够提供脂肪 干细胞（ADSC）和修复PAF通过调节炎症反应，允许宿主细胞浸润， 促进血管生成和进行性重塑。在这些初步结果的基础上，我们计划 第二代NHC插头具有增强的机械强度和完整性，作为现成的装置， 优化其生物刺激活性以诱导更有利的控制瘘管愈合的细胞反应。我们 假设这种具有结构、机械和生物功能优化特征的NHC塞将 有效促进血管生成和软组织修复;并作为ADSC和ADSC- 衍生的外泌体以进一步改善PAF组织愈合。为了验证这一假设并证明其 翻译潜力，我们将追求三个具体目标（1）开发一种基于胶原纳米纤维的NHC塞， 最佳的机械性能和多孔结构，易于植入，以支持肛瘘愈合， (2)利用大鼠模型评估单独使用或与ADSC联合使用时PAF愈合的功效，或 ADSC衍生的外泌体，并通过评估细胞浸润阐明促再生机制， 血管生成、细胞外基质沉积和组织重塑，以及（3）利用猪模型， 通过将优化的NHC塞与ADSC衍生的 外来体本研究将提供一个可翻译的现成的仿生NHC微孔塞的交付 ADSC衍生的外泌体能够促进软组织重塑和愈合，用于PAF修复。

SUMMARY Perianal fistulas (PAF) occur in 30-40% of Crohn’s disease patients and their complications lead to a significant impairment in quality of life. Current treatments are effective in less than 50% of cases. The overall objective of this proposed study is to develop a biostimulatory nanofiber-hydrogel composite (NHC) plug to promote tissue healing and to test its efficacy to repair PAF in clinically relevant animal models. Previous work from the Mao and Selaru labs laid the foundation for this study. Specifically, we have established novel rodent and swine models of PAF that faithfully recapitulate the biology of PAF in patients. In parallel, we have developed a first-generation injectable biodegradable nanofiber-hydrogel composite (NHC) from poly(e-caprolactone) (PCL) nanofibers covalently bonded to hyaluronic acid (HA) hydrogel; and demonstrated its ability to deliver adipose stem cells (ADSCs) and repair PAF by conditioning inflammatory responses, permitting host cell infiltration, and facilitating angiogenesis and progressive remodeling. Building on these preliminary results, we plan to engineer a second generation NHC plug with enhanced mechanical strength and integrity as an off-the-shelf device and optimize its biostimulatory activities to induce more favorable cellular responses governing fistula healing. We hypothesize that this NHC plug with structurally, mechanically, and biofunctionally optimized features will effectively promote angiogenesis and soft tissue restoration; and serve as a carrier for ADSCs and ADSC- derived exosomes to further improve the PAF tissue healing. To test this hypothesis and demonstrate its translational potential, we will pursue three specific aims (1) develop a collagen nanofiber-based NHC plug with optimal mechanical properties and porous structure for ease of implantation to support perianal fistula healing, (2) utilize a rat model to evaluate the efficacy for PAF healing when used alone or in conjunction with ADSCs or ADSC-derived exosomes, and elucidate the pro-regenerative mechanism by assessing cell infiltration, angiogenesis, extracellular matrix deposition, and tissue remodeling, and (3) utilize a swine model to demonstrate the synergistic effect in tissue remodeling by combining the optimized NHC plug with ADSC-derived exosomes. This study will deliver a translatable off-the-shelf biomimetic NHC microporous plugs for the delivery of ADSC-derived exosomes capable of promoting soft tissue remodeling and healing for PAF repair.