Erythromycin-doped nanofiber coating to increase implant longevity

骨结合失败(通过骨-种植体表面的骨形成直接固定种植体) 种植体感染是导致种植体失败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，尤其是 当被放置在因疾病或患者生理损害而受损的骨骼中时。这项研究的目标是 开发一种杀菌的“类骨”纳米纤维(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，我们开发了同轴电纺纤维 由聚(丙交酯-乙交酯)(PLGA)和聚乙烯醇(PVA)聚合物组成，聚合物排列在一个核心- 护套配置。PLGA是FDA批准的一种共聚物，具有长期的临床经验，可作为药物的载体 持续的药物释放。将I型胶原(Col)包埋在PLGA中，形成具有生物活性的PLGACol鞘 纤维。PVA具有良好的成纤维能力，将用于纳米级羟基磷灰石(HA)的包覆 形成亲水性PVAHA芯纤维。PLGACol/PVAHA NFS具有生物相容性和可生物降解性 合适的纤维直径、孔径和机械强度，可增强细胞的粘附性、增殖性 骨髓基质细胞(BMSCs)的分化。在拟议的研究中，我们将植入红霉素 (EM，杀菌和抗破骨)进入PLGACol/PVAHA NFS.我们假设，NFS将模仿 天然骨的生物、结构和力学行为，并增强其黏附、生长和 骨髓间充质干细胞的分化。我们认为，EM在PLGACol/PVAHA网络中的嵌入会抑制 细菌定植，促进种植体骨结合，因其具有促进骨愈合的活性。 我们将通过追求三个目标来验证我们的假设：目标1：开发一个最优的PLGACol/PVAHA NF 钛(钛)种植体涂层的配方：(A)确定基于细胞的最佳核因子配方 对大鼠BMSCs的活性、增殖和成骨分化的响应，以及(B)进一步优化 在体外猪骨种植模型中核因子涂层与钛种植体的结合强度；目的2： 表征EM掺杂PLGACol/PVAHA-NFS膜对细胞反应、细菌生长的影响 和体外生物膜的形成。我们认为，EM掺杂将改变非晶玻璃的物理化学性质 (形态、表面拓扑、降解、机械强度和电磁释放动力学，目标2a)， 将影响细胞反应(大鼠骨髓间充质干细胞的活性、增殖和成骨分化，Aim 2b)， 细菌生长和生物膜形成(金黄色葡萄球菌的粘附力、活力和生物膜形成， 和目标3：确定EM掺杂PLGACol/PVAHANF对感染的影响 金黄色葡萄球菌感染的大鼠胫骨植入模型中的抑制和骨整合。我们将决定 EM-NF涂层是否足以抑制种植体感染(细菌培养、生物膜形成)和 加强骨整合(拔出试验、骨组织形态计量学、微型计算机断层扫描、CT)。我们 预计EM从NF涂层中的持续释放将抑制种植体感染并进一步促进 骨整合由于其已被证实的成骨和杀菌活性。 这项拟议的工作是创新的，因为它利用了一种新的植入物表面制造策略 通过提供“骨状”的纳米级拓扑结构和可控的缓释药物储存库。这是我们的 期望由此产生的方法将提供确凿的证据，支持拟议的 与目前可用的医疗设备相比，Nf涂层医疗设备具有更高的性能。这些结果将是重要的，因为它们是 以期提高全关节置换术的成功率，延长植入物寿命。它不应该是 明显增加了植入物的成本。这将改善这些患者的生活质量，并提供 显著节省医疗成本。

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.