Angiogenic and anti-microbial supports for pulp regeneration

项目概述：牙髓是牙齿中至关重要的微环境，拥有血管和 神经，更不用说与牙本质小管接触的成牙本质细胞。创伤或细菌感染可能 牙髓发炎，造成极度疼痛摘除发炎的牙髓（并可能用惰性的 材料）改善疼痛，但该过程留下了失活的牙齿。在青少年中， 患者，称为过度使用器械（OI）。在OI期间，牙髓腔暴露于外周循环 牙髓切除术后只要根尖乳头是完整的，牙髓管中就会发生一些组织再生 随后-尽管紊乱的组织不模仿天然软组织。尤其是成年人， 导致非功能性牙髓骨化。根管治疗过程中的另一个问题是发生/复发 口腔细菌的定植。这种感染可能会延长和加剧牙髓炎症。一种材料- 提出了一种基于的制剂，其可以（a）促进牙髓中的血管化软组织再生，而（B） 抵抗细菌感染。我们的策略依赖于自组装肽水凝胶-一类超分子 可以在体内注射同时保持其凝胶状性质的材料。这些材料包括典型的 氨基酸并且是生物相容的。这种材料需要同时提供机械支撑和生物暗示 组织向内生长有点反直觉，自组装肽水凝胶，没有额外的增长 因子或外源性细胞，证实了在犬牙髓切除模型中血管化软组织的形成， 28天在一项单独的研究中，属于同一平台的不同阳离子两亲性水凝胶显示， 通过膜透化抑制细菌生长的功效。在这个建议中，一种组合治疗方法 将检验这一模式在实现上述双重目标方面的有效性。一个机械难题 这些项目将帮助解决的问题是浸润细胞的谱系/来源和细胞环境的进化 在牙髓切除术和软仿生水凝胶植入后的牙髓管中。长期以来， 由此类水凝胶促进的血管化软组织的成熟是另一个目标。多- 在这个生物工程研究资助申请中提出的学科项目将汇集一位化学家 和生物工程师（PI V.A.K.，早期研究者），口腔细菌菌落专家（co-I C.C.），和 牙髓病医生（co-I E.S.），解决一个持久的挑战：再生仿生血管化软组织后， 牙髓切除术体外机制分析、浸润细胞的体内表征和组织学/放射学 牙髓软组织和牙髓-牙本质复合体的长期演变的鉴定将建立在已发表的 研究和广泛的初步数据。即使所提出的实验只是部分成功，我们也会 了解牙髓中的组织-材料相互作用。目标的成功将产生 无细胞、无生长因子、现成材料配方的令人信服的数据， 在数百万需要进行牙髓切除术的患者中，

Project Summary: The dental pulp is the vital microenvironment in the tooth, harboring blood vessels and nerves, not to mention odontoblasts that interface with the dentinal tubules. Trauma or bacterial infection may inflame the dental pulp, creating extreme pain. Extirpating the inflamed pulp (and potentially replacing it with inert materials) ameliorates the pain, but the procedure leaves a devitalized tooth. An alternative is possible in juvenile patients, called over-instrumentation (OI). During OI, the pulpal chamber is exposed to the peripheral circulation post-pulpectomy. As long as the apical papilla is intact, some tissue regeneration takes place in the pulpal canal subsequently — although the disorganized tissue does not mimic native soft tissue. In adults in particular, OI results in non-functional pulpal ossification. Another concern in endodontic procedures is occurrence/recurrence of colonization by oral bacteria. Such infections may prolong and exacerbate pulpal inflammation. A material- based formulation is proposed that can (a) promote vascularized soft-tissue regeneration in the pulp, while (b) resisting bacterial infection. Our strategy rests on self-assembling peptide hydrogels — a class of supramolecular materials that can be injected in vivo while keeping their gel-like properties. The materials consist of canonical amino acids and are biocompatible. Such materials need to provide both mechanical support and biological cues for tissue ingrowth. Somewhat counter-intuitively, a self-assembling peptide hydrogel, without added growth factors or exogenous cells, demonstrated formation of vascularized soft-tissue in a canine pulpectomy model in 28 days. In a separate study, a different cationic amphiphilic hydrogel belonging to the same platform, showed efficacy in inhibiting bacterial growth via membrane permeabilization. In this proposal, a combinatorial treatment modality will be tested for its effectiveness in achieving the dual goals described above. A mechanistic puzzle that these projects would help solve is the lineage/source of infiltrating cells and evolution of the cellular milieu in the pulpal canal after pulpectomy and implantation of soft biomimetic hydrogels. Characterization of the long- term maturation of the vascularized soft tissue promoted by such hydrogels is another target. The multi- disciplinary project proposed in this Bioengineering Research Grant application would bring together a chemist and bioengineer (PI V.A.K., an early-stage investigator), a specialist in oral bacterial colonies (co-I C.C.), and an endodontist (co-I E.S.), to solve an enduring challenge: regenerating biomimetic vascularized soft tissue post- pulpectomy. In vitro mechanistic analyses, in vivo characterization of infiltrating cells, and histologic/radiographic identification of long-term evolution of the pulpal soft tissue and the pulp-dentin complex would build on published studies and extensive preliminary data. Even if the proposed experiments are only partially successful, we would learn about tissue-material interaction in the context of dental pulp. Success of the aims would produce compelling data for a cell-free, growth-factor-free, off-the-shelf material formulation ideal for application in endodontic settings and improve clinical outcomes in millions of patients needing pulpectomy.