Oxygen-eluting scaffolds for cranial bone regeneration

在美国，每年大约有20万例颅面骨折需要进行骨移植 20亿美元的经济负担。这些损伤通常需要多次复杂的手术，但不能达到 适当的功能或美观的恢复。为了解决这一限制，组织工程领域已经 采用了先进的方法，将患者自己的细胞与定制的生物活性支架相结合， 诱导再生。为了有效地进行组织工程策略的临床翻译，开发 它们作为护理点式技术，在这种技术中，细胞的收获、细胞的包装进入支架，以及 立即移植到缺损处将在一次外科手术中进行。一个主要的障碍 这一策略的关键是低氧创伤微环境阻碍了存活细胞协调 再生。为了克服这一限制，我们建议设计能够输送氧气(O2)的支架 和细胞一起。具体地说，我们将嵌入氧气洗脱微槽(微槽)-中空的聚合物 能够在高压下‘储存’氧气并将其缓慢释放到细胞内的微球 微环境-聚己内酯(PCL)和脱细胞骨基质(DCB)组成的支架 以精确的解剖形状进行3D打印。为了有效地设计氧气洗脱、PCL-DCB-微槽支架 并追踪移植的基质血管成分(SVF)细胞的活性和治疗效果的提高 从脂肪抽吸物中获得，我们将利用体内多模式光学成像。这将提供定量数据 影响干细胞存活和组织再生的体内微环境因素 移植并为设计过程提供独特的信息，从而实现更有效的下一代生物材料 脚手架。我们假设，使用我们的微罐技术输送氧气长达四天将 通过非侵入性方法增强干细胞在缺损区内的存活、血管形成和骨形成 通过颅窗监测氧气输送的效果，我们可以优化支架的设计。在……里面 具体目标1，我们将制造直径10-50微米的可生物降解的聚乙烯醇微罐， 将它们整合到3D打印支架的支柱中，并验证其中的时空O2梯度 支架在不同的微槽浓度和加载压力下的响应。在具体目标2中，我们 将整合最有利于血管形态发生/成骨的氧气浓度的实验数据 用数值模拟区分SVF以预测提供有利条件的支架设计 时空氧气梯度，以促进组织再生。在具体目标3中，我们将使用非侵入性、 多模式成像动态监测PCL-DCB-µ池移植细胞和血管集合体 脚手架，并使用此来增强脚手架设计。我们将在放大的、严格的、 骨再生的血管限制模型。互补的组织工程/成像优势将 为骨再生提供前所未有的洞察力，并产生新的平台生物材料技术。

Each year, there are approximately 200,000 craniofacial fractures requiring bone transplantation in the US with an economic burden of $2B. These injuries often require multiple complex surgeries, which do not achieve adequate functional or aesthetic restoration. To address this limitation, the field of tissue engineering has employed advanced approaches that combine a patient’s own cells with customized bioactive scaffolds to induce regeneration. For efficacious clinical translation of tissue engineering strategies, it is crucial to develop them as point-of-care technologies in which the harvesting of cells, their packaging into scaffolds, and immediate transplantation into the defect site will take place within a single surgical procedure. A major hurdle of this strategy is that the hypoxic wound microenvironment impedes the ability of surviving cells to orchestrate regeneration. To overcome this limitation, we propose to design scaffolds capable of delivering oxygen (O2) along with the cells. Specifically, we will embed O2-eluting microtanks (µtanks) – hollow, polymeric microspheres capable of ‘storing’ O2 at elevated pressures and slowly releasing it into the cellular microenvironment – into scaffolds comprised of polycaprolactone (PCL) and decellularized bone matrix (DCB) that are 3D-printed in precise, anatomic shapes. To effectively design O2-eluting, PCL-DCB-µtank scaffolds and track the enhanced viability and therapeutic efficacy of transplanted stromal vascular fraction (SVF) cells harvested from lipoaspirate, we will utilize multimodal in vivo optical imaging. This will provide quantitative data on the in vivo microenvironmental factors that impact stem cell survival and tissue regeneration following transplantation and uniquely inform the design process leading to more effective, next-generation biomaterial scaffolds. We hypothesize that the delivery of oxygen using our microtank technology for up to four days will enhance stem cell survival, vascularization and bone formation within the defect and that by non-invasively monitoring the effects of oxygen delivery via a cranial window, we can optimize the design of the scaffold. In Specific Aim 1, we will manufacture 10-50 µm diameter biodegradable polyvinyl alcohol microtanks, incorporate them into the struts of the 3D-printed scaffolds, and validate the spatiotemporal O2 gradients within the scaffolds in response to varying the microtank concentrations and loading pressures. In Specific Aim 2, we will integrate experimental data of O2 concentrations most favorable to vascular morphogenesis/osteogenic differentiation of SVF with numerical simulations to predict the scaffold designs that provide favorable spatiotemporal O2 gradients to promote tissue regeneration. In Specific Aim 3, we will utilize non-invasive, multimodal imaging to dynamically monitor transplanted cells and vascular assembly in PCL-DCB-µtank scaffolds and use this to enhance scaffold design. We will test the optimal designs in a scaled-up, stringent, vasculature-limited model of bone regeneration. The complementary tissue engineering/imaging strengths will provide unprecedented insight into bone regeneration and produce novel platform biomaterial technologies.