Biomaterial regulation of cell spheroids to synergistically enhance bone healing

细胞球体的生物材料调节协同增强骨愈合

• 批准号: 8968201
• 负责人: J. Kent Leach
• 金额: $ 35.89万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8968201
• 关键词: Adhesions; Adhesives; Affect; Alginates; Angiogenic Factor; Animals; Apoptosis; Binding; Biochemical; Biocompatible Materials; Biological Assay; Biomechanics; Bone Regeneration; Calvaria; Cell Adhesion; Cell Communication; Cell Culture Techniques; Cell Survival; Cell Therapy; Cell Transplantation; Cell Transplants; Cell physiology; Cells; Coupling; Data; Defect; Development; Endogenous Factors; Engineering; Equilibrium; Fracture; Gel; Geometry; Healed; Human; Hydrogels; Immunohistochemistry; Implant; In Situ; In Vitro; Injectable; Injection of therapeutic agent; Intervention; Ligands; Measures; Mechanics; Mesenchymal; Metabolic; Methods; Morbidity - disease rate; Natural regeneration; Operative Surgical Procedures; Osteogenesis; Peptides; Polymers; Process; Property; RGD (sequence); Rattus; Regulation; Research; Rodent; Role; Site; Source; Speed; Stem cells; Stromal Cells; Testing; Therapeutic; Tissue Engineering; Tissues; Transplantation; Vascularization; Vertebral column; base; biophysical properties; bone; bone healing; cellular engineering; cohesion; cost effective; crosslink; density; healing; imaging modality; implantation; innovation; monolayer; neovascularization; non-invasive imaging; novel strategies; osteogenic; protein aminoacid sequence; public health relevance; receptor; regenerative; repaired; response; stem; tissue regeneration; tissue repair; tool

 DESCRIPTION (provided by applicant): Of the greater than 6 million fractures occurring yearly in the US, up to 20% will result in nonunion or delayed union, thereby requiring intervention for bone regeneration. Mesenchymal stem/stromal cells (MSCs) are an attractive cell source for cell-based therapies of bone healing because of their osteogenic potential and robust secretion of proangiogenic trophic factors. Culture dimensionality has a profound impact on a myriad of cell functions. Compared to dissociated MSCs, our recent data demonstrate that MSC spheroids secrete 100- fold higher levels of angiogenic factors and better resist apoptosis while maintaining osteogenic potential. Spheroid formation is a competition between cohesion and adhesion, and optimizing this balance through the entrapment in engineered biomaterials provides an exciting opportunity to instruct the regenerative potential of MSCs after transplantation. Hydrogel properties such as adhesivity, stiffness, and degradation influence the function of entrapped cells and resulting tissue formation. Alginate is a highly cytocompatible natural polymer that is amenable to control of initial mechanical properties through composition and crosslinking, as well as adhesivity by covalently coupling peptide sequences such as Arg-Gly-Asp (RGD) to the polymer backbone that bind cellular receptors. Thus, alginate hydrogels represent an ideal tool to probe the role of substrate properties on spheroid function. Our central hypothesis is that the therapeutic potential of MSC spheroids for bone regeneration can be enhanced using alginate hydrogels with engineered biophysical properties. Aim 1. Does adhesion ligand density within alginate hydrogels affect the survival, proangiogenic, and osteogenic potential of entrapped MSC spheroids? We will synthesize alginate hydrogels with varying densities of RGD. The influence of increased adhesion versus cohesion on spheroid function will be determined. Aim 2. Do hydrogel biomechanical properties influence the functional response of entrapped MSC spheroids? Using composite hydrogels with distinct biophysical properties, we will examine the role of substrate stiffness and degradation on survival, proangiogenic and osteogenic potential of entrapped MSC spheroids. Aim 3. Can MSC spheroids transplanted in RGD-modified hydrogels with optimized biophysical properties accelerate bone formation in a critical-sized calvarial bone defect? We will characterize the capacity of MSC spheroids transplanted in RGD-modified alginate hydrogels to accelerate bone repair in an orthotopic defect compared to dissociated MSCs. The role of implanted cells, as well as quality of bone formation will be assessed using noninvasive imaging modalities. The proposed research is innovative because it exploits the balance of cellular aggregation versus adhesion to drive cell fate using an injectable, biodegradable hydrogel to potentiate the reparative potential of MSCs. This research will provide a new approach to drive bone formation in nonhealing or slow healing bone fractures, and the strategies have potential in enhancing the efficacy of materials-based therapies for tissue repair.

 描述（由申请人提供）：在美国每年发生超过 600 万例骨折中，高达 20% 会导致骨不连或延迟愈合，因此需要进行骨再生干预，间充质干细胞/基质细胞 (MSC) 是一种有吸引力的治疗方法。与分离的细胞相比，其具有成骨潜力和促血管生成营养因子的强劲分泌，因此是基于细胞的骨愈合疗法的细胞来源。 MSCs，我们最近的数据表明，MSC 球体分泌的血管生成因子水平高出 100 倍，并能更好地抵抗细胞凋亡，同时保持成骨潜力。球体形成是内聚力和粘附力之间的竞争，通过工程生物材料的包埋来优化这种平衡提供了令人兴奋的结果。移植后指示间充质干细胞再生潜力的机会海藻酸盐是一种高度细胞相容性的天然聚合物，可通过组成和交联控制初始机械性能，以及通过将精氨酸-甘氨酸-天冬氨酸 (RGD) 等肽序列共价偶联至结合细胞受体的聚合物主链来控制粘附性。因此，藻酸盐水凝胶是探索基质特性对球体功能的作用的理想工具。 假设使用具有工程生物物理特性的藻酸盐水凝胶可以增强 MSC 球体的骨再生治疗潜力。目标 1。藻酸盐水凝胶内的粘附配体密度是否会影响捕获的 MSC 球体的存活、促血管生成和成骨潜力？具有不同 RGD 密度的藻酸盐水凝胶将确定增加的粘附力与内聚力对球体功能的影响。 2. 水凝胶的生物力学特性是否影响捕获的 MSC 球体的功能反应？使用具有独特生物物理特性的复合水凝胶，我们将研究基质硬度和降解对移植到 RGD 中的捕获的 MSC 球体的存活、促血管生成和成骨潜力的作用。具有优化生物物理特性的改良水凝胶可加速临界尺寸颅骨骨缺损的骨形成？我们将表征 MSC 的能力与分离的 MSC 相比，移植到 RGD 修饰的藻酸盐水凝胶中的球体可加速原位缺损的骨修复。将使用非侵入性成像方式评估植入细胞的作用以及骨形成的质量。使用可注射、可生物降解的水凝胶平衡细胞聚集与粘附来驱动细胞命运，以增强 MSC 的修复潜力。在不愈合或愈合缓慢的骨折中驱动骨形成的新方法，这些策略有可能提高基于材料的组织修复疗法的功效。