Erythromycin-doped nanofiber coating to increase implant longevity

骨整合失败（通过骨-种植体表面的骨形成直接锚定种植体） 和种植体感染是导致种植体失效和松动的两个主要原因。迫切需要 骨科植入物，既促进快速骨整合，又防止细菌定植，特别是 当被放置在因疾病或患者生理而受损的骨中时。本研究的目的是 开发一种杀菌的“骨样”骨（NF）涂层，以增强骨整合，同时防止 植入物感染。为了模仿天然骨基质的结构，我们开发了同轴静电纺丝NF 由排列在核中的聚（丙交酯-共-乙交酯）（PLGA）和聚乙烯醇（PVA）聚合物组成， 鞘管配置。PLGA是FDA批准的共聚物，具有长期的临床经验，可作为 药物缓释将I型胶原（Col）包埋在PLGA中以形成生物活性PLGACol鞘 光纤聚乙烯醇具有良好的成纤能力，有望用于包裹纳米羟基磷灰石（HA） 以形成亲水性PVAHA芯纤维。PLGACol/PVAHA NF具有生物相容性和生物可降解性， 合适的纤维直径、孔径和机械强度，导致细胞粘附、增殖增强 和骨髓基质细胞（BMSCs）的分化。在拟议的研究中，我们将嵌入红霉素 (EM、杀菌和抗骨质疏松）转化为PLGACol/PVAHA NF。我们假设神经纤维会模仿 天然骨的生物学、结构和力学行为，并增强骨的粘附、生长和 BMSCs的分化。我们提出，在PLGACol/PVAHA NF中嵌入EM将抑制 细菌定植和促进种植体骨整合，因为它的刺激活性的骨愈合。 我们将通过追求三个目标来测试我们的假设：目标1：开发最佳PLGACol/PVAHA NF 钛（Ti）植入物涂层的配方：（a）根据细胞生物学特性定义最佳NF配方 反应（大鼠BMSC的活力、增殖和成骨分化），和（B）进一步优化 在离体猪骨植入模型中NF涂层与钛植入物的结合强度;目的2： 表征PLGACol/PVAHA NF的EM掺杂对细胞反应、细菌生长和细胞增殖的影响。 和体外生物膜形成。我们认为EM掺杂将改变NF的物理化学性质 （形态、表面拓扑、降解、机械强度和EM释放动力学，目标2a）， 将影响细胞反应（大鼠BMSC的活力、增殖和成骨分化，目标2b）， 以及细菌生长和生物膜形成（金黄色葡萄球菌的粘附、存活力和生物膜形成， S.目的2c）和目的3：确定PLGACol/PVAHANF的EM掺杂对感染的影响 抑制和骨整合。金黄色葡萄球菌感染的胫骨植入模型。我们将确定 EM-NF涂层是否足以抑制植入物感染（细菌培养、生物膜形成），以及 增强骨整合（拔出试验、骨组织形态计量学和微型计算机断层扫描，CT）。我们 预期从NF涂层持续释放EM将抑制植入物感染并进一步促进 由于其已被证实的成骨和杀菌活性， 拟议的工作是创新的，因为它利用了一种新的战略，种植体表面制造 通过提供“骨样”纳米级拓扑结构和可控持续药物释放的储库。是我们 期望由此产生的方法将提供坚实的证据，有利于所提出的优点， NF涂层医疗器械优于目前可用的医疗器械。这些结果将是重要的，因为它们是 预期可提高全关节置换术的成功率并延长植入物寿命。它不应该 明显增加了植入物的成本。这将改善这些患者的生活质量，并为他们提供一个 节省大量医疗费用。

Failure of osseointegration (direct anchorage of an implant by bone formation at the bone-implant surface) and implant infection are the two main causes of implant failure and loosening. There is an urgent need for orthopedic implants that both promote rapid osseointegration and prevent bacterial colonization, particularly when placed in bone compromised by disease or the physiology of the patients. The goal of this study is to develop a bactericidal “bone-like” nanofiber (NF) coating to enhance osseointegration while preventing implant infection. To imitate the architecture of the natural bone matrix, we developed coaxial electrospun NFs composed of poly (lactide-co-glycolide) (PLGA) and polyvinyl alcohol (PVA) polymers arranged in a core- sheath configuration. PLGA is a FDA-approved co-polymer with long clinical experience as a carrier for sustained drug release. Type I collagen (Col) was embedded in the PLGA to form a bioactive PLGACol sheath fiber. PVA has a good fiber-forming capability and will be used to encapsulate nanoscale hydroxyapatite (HA) to form a hydrophilic PVAHA core fiber. The PLGACol/PVAHA NFs are biocompatible and biodegradable with appropriate fiber diameter, pore size and mechanical strength, leading to enhanced cell adhesion, proliferation and differentiation of bone marrow stromal cells (BMSCs). In the proposed study, we will embed erythromycin (EM, bactericidal and anti-osteoclastic) into PLGACol/PVAHA NFs. We hypothesize that NFs will mimic the biological, structural and mechanical behaviors of natural bone, and enhance the adhesion, growth and differentiation of BMSCs. We propose that the embedding of EM in the PLGACol/PVAHA NFs will inhibit bacterial colonization and promote implant osseointegration because of its stimulatory activity of bone healing. We will test our hypothesis by pursuing three Aims: Aim 1: Develop an optimal PLGACol/PVAHA NF formulation for titanium (Ti) implant coating: (a) Define an optimal NF formulation based on the cellular response (viability, proliferation and osteogenic differentiation of rat BMSCs, and (b) Further optimize the bonding strength of NF coating to the Ti implant in an ex vivo porcine bone implantation model; Aim 2: Characterize the effects of EM doping of PLGACol/PVAHA NFs on the cellular response, bacterial growth and biofilm formation in vitro. We propose that EM doping will change the physiochemical nature of NFs (morphology, surface topology, degradation, mechanical strength and EM release dynamics, Aim 2a), which will impact on the cellular response (viability, proliferation and osteogenic differentiation of rat BMSCs, Aim 2b), and bacterial growth and biofilm formation (adhesion, viability and biofilm formation of Staphylococcus aureus, S. aureus, Aim 2c), and Aim 3: Determine the effects of EM doping of PLGACol/PVAHANFs on infection inhibition and osseointegration in a rat S. aureus- infected tibia implantation model. We will determine whether the EM-NF coating is sufficient to inhibit implant infection (bacterial culture, biofilm formation) and enhance osseointegration (pullout test, bone histomorphometry, and micro computed tomography, CT). We expect that a sustained release of EM from NF coating will inhibit implant infection and further promote osseointegration due to its proven osteogenic and bactericidal activities. The proposed work is innovative, because it capitalizes on a new strategy of implant surface fabrication by providing a “bone-like” nanoscale topology and a reservoir of controllable sustained drug release. It is our expectation that the resultant approach will provide solid evidence favoring the advantages of the proposed NF coated medical devices over those currently available. These results will be significant, because they are expected to improve the success of total joint replacement and increase implant longevity. It should not appreciably increase the cost of the implant. This will improve the quality of life for these patients and provide a significant healthcare savings.