Heat-Treated Porous Fluorapatite Scaffolds with Adipose Derived Stem Cells for Bone Regeneration

由于高能量创伤（如战场创伤）导致的节段性骨丢失是威胁肢体的情况，但 可供选择的治疗方法有限。传统的治疗方法包括骨移植，血管化骨 移植和同种异体移植。使用血管化自体移植物进行骨修复可以说是目前最好的方法， 因为修复过程将利用患者自身的组织和血液供应进行， 在手术的时候。这消除了许多与同种异体移植和生物工程相关的不良结果。 骨替代品然而，供体自体移植部位有限，因此，其供应不能满足需求。它 还需要第二个手术部位，这可能导致进一步的合并症。脱细胞同种异体移植物 从尸体来源获得的具有骨传导性的优点。然而，它们与 具有宿主排斥和加速移植物再吸收的风险。目前的生物工程移植物的重点是提供 通过提供生物相容性、生物可吸收性和多孔支架来支持骨再生的必要基质 由诸如羟基磷灰石、胶原蛋白和合成材料的材料制成。现在很明显，生物工程 移植物还需要可靠的成骨祖细胞来源以及成骨信号 骨替代品为了改进这些最初的设计，研究人员制作了新的支架， 细胞外基质蛋白或生长因子，通常是骨形态发生蛋白（BMP），但具有有限的 成功通常，支架的强度仍然是手术后承重的主要障碍。本 最后，我们采用“凝胶注模”工艺制备了一种完全互连的多孔氟磷灰石（FA）支架， 然后进行热处理以优化机械强度。由于这些表面是成骨的， 成骨细胞粘附、增殖和分化。有趣的是，这些支架还具有 将干细胞（脂肪来源的干细胞）分化成骨谱系而没有任何成骨信号（例如， 外源性BMP）。更值得注意的是，“凝胶浇铸”技术允许定制所需形状的制造， 刚性支架的尺寸，以适应个别缺陷。因此，我们假设，FA支架接种了一个 患者自身的脂肪组织来源的基质血管部分（SVF）干细胞将具有以下能力： 再生骨组织。这一假设将在三个目标进行检验。具体目标1将调查 多孔氟磷灰石支架的机械、物理和降解性能， 通过凝胶浇铸技术。具体目标2将量化体外粘附和分化特性， 多孔FA表面上的SVF细胞。具体目标3将研究FA支架的成骨潜力 在大鼠股骨髁模型中有和没有SVF。预期这种SVF和SVF的组合治疗是有效的。 FA支架将为临床骨修复提供“现成”支架材料的潜在来源， 再生和改善健康和生活质量的一些军事人员，退伍军人和平民。 ! !

Segmental bone loss due to high-energy trauma, such as battlefield injuries, are limb-threatening conditions, but there are limited treatment options available. Conventional treatments include bone grafts, vascularized bone transplant, and allografts. Bone repair using vascularized autografts is arguably the best current approach, because the repair process will proceed with the patient’s own tissue and blood supply, which can be harvested at the time of surgery. This eliminates many adverse outcomes associated with allografts and bioengineered bone substitutes. However, donor autograft sites are limited, and thus, its supply cannot meet the demand. It also requires a second surgical site, which could result in further comorbidities. Decellularized allografts harvested from cadaveric sources have the advantage of being osteoconductive. However, they are associated with risk of host rejection and accelerated graft resorption. Current bioengineered grafts focus on providing the necessary matrix to support bone regeneration by providing biocompatible, bioresorbable, and porous scaffolds made from materials such as hydroxyapatite, collagen and synthetic materials. It is now clear that bioengineered grafts also need a reliable source of osteogenic progenitor cells as well as osteogenic signals to be effective bone substitutes. To improve upon these initial designs, researchers made new scaffolds that integrated extracellular matrix proteins or growth factors, typically bone morphogenetic proteins (BMPs), but with limited success. Often the strength of the scaffolding remains the main hurdle for weight-bearing after surgery. To this end, we fabricated a fully interconnecting porous fluorapatite (FA) scaffold by adopting a “gel-casting” process, and then heat-treating to optimize the mechanical strength. As these surfaces are osteogenic, they also enhance osteoblast adhesion, proliferation, and differentiation. Interestingly, these scaffolds also possess the ability to differentiate stem cells (adipose derive stem cells) to an osteogenic lineage without any osteogenic signals (e.g. exogenous BMPs). More notably, the “gel-casting” technique allows custom fabrication of desired shapes and sizes of rigid scaffoldings to fit individual defects. Thus, we hypothesize that FA scaffoldings seeded with a patient’s own adipose tissue-derived stromal vascular fraction (SVF) stem cells will have the ability to regenerate osseous tissue. This hypothesis will be tested in three aims. Specific Aim 1 will investigate the mechanical, physical, and degradation properties of the porous fluorapatite scaffolds, which will be generated by the gel-casting technique. Specific Aim 2 will quantify the in vitro adhesion and differentiation properties of the SVF cells on porous FA surfaces. Specific Aim 3 will investigate the osteogenic potential of the FA scaffolding with and without SVF in a rat femoral condyle model. It is expected that such combination treatment of SVF and FA scaffolds will provide a potential source of “off-the-shelf” scaffolding materials for clinical bone repair and regeneration and improve the health and quality of life for a number of military personnel, veterans, and civilians. ! !