In situ BMSC Seeding of 3D Printed Scaffolds Using Cell-releasing Hydrogels

细胞释放水凝胶原位种植3D打印支架 在目前的方案中，我们将研究3D打印的PolyHIPE移植物的BMSC原位种植对 骨形成。细胞释放水凝胶载体与先进三维制造的结合 技术有可能产生具有患者特定几何形状和增强的骨骼的移植物 再生。为此，我们最近开发了一种多模式打印系统来生成组织工程 模仿骨骼天然结构的支架。在该体系中，富马酸系乳液油墨具有层次化特点 孔隙率(PolyHIPE)用聚乳酸外壳增强，以实现同时改善 渗透性和抗压性能。除了支架的设计性能外，成功的作为一种骨移植 依赖于骨髓基质细胞(BMSC)的交付或招募，这些细胞通过 多种机制，包括作为新的骨形成中心和营养因子的分泌， 调节炎症，刺激血管生成，抑制纤维化。我们已经开发出一种可生物降解的细胞- 释放水凝胶载体在手术时原位愈合种植我们的3D打印骨移植 在最初的炎症阶段之后，随后的细胞释放到支架上。牛骨髓间充质干细胞原位播种 支架有可能最大限度地降低成本、治疗延迟和延长预付款的监管障碍 文化时期。在授权期结束时，我们将确定改善的目标细胞释放情况 异位骨模型中细胞滞留和骨髓间充质干细胞启动的成骨作用。这将提供强有力的证据证明 细胞种子骨移植的成骨特性及其对未来大型动物研究的支持 正交各向异性模型(R01)。除了改进植骨程序外，这些研究还将验证一种方法 可以在广泛的应用中使用的BMSC交付。

IN SITU BMSC SEEDING OF 3D PRINTED SCAFFOLDS USING CELL-RELEASING HYDROGELS In the current proposal, we will investigate the effect of in situ BMSC seeding of 3D printed polyHIPE grafts on bone formation. The combination of the cell-releasing hydrogel carrier with advanced 3D manufacturing technologies has the potential to generate a graft with patient-specific geometries and enhanced bone regeneration. To this end, we recently developed a multi-modal printing system to generate tissue engineered scaffolds that mimic the native structure of bone. In this system, fumarate-based emulsion inks with hierarchical porosity (polyHIPE) were reinforced with a poly(lactic acid) shell to achieve simultaneous improvements in permeability and compressive properties. In addition to the design of scaffold properties, success as a bone graft depends on the delivery or recruitment of bone marrow stromal cells (BMSC) that aid regeneration through a variety of mechanisms including serving as new centers of bone formation and secretion of trophic factors that modulate inflammation, stimulate angiogenesis, and limit fibrosis. We have developed a biodegradable cell- releasing hydrogel carrier that cures in situ to seed our 3D printed bone graft with BMSC at the time of surgery with subsequent cell release onto the scaffold after the initial inflammatory period. In situ BMSC seeding of scaffolds has the potential to minimize the costs, treatment delays, and regulatory hurdles of extended pre- culture periods. At the end of the grant period, we will have identified the target cell-release profile that improves cell retention and BMSC-initiated osteogenesis in an ectopic bone model. This will provide strong evidence of the osteoinductive character of the cell-seeded bone graft and support future investigation in a large animal orthotropic model (R01). In addition to improving bone grafting procedure, these studies will validate a method of BMSC delivery that can be used in a broad range of applications.