Novel Nanostructured Calcium Phosphate for Gene Delivery to Bone

描述(由申请人提供)：骨质疏松症是一个主要的和日益严重的健康保健问题，对标准的药物治疗反应不足。由于骨质疏松骨密度较低，其力学性能较弱，比正常骨更容易发生骨折。此外，骨质疏松症患者的骨折修复也受到影响。这项第一阶段STTR提案中描述的工作旨在开发一种负载纳米结构磷酸钙(NCAP)底物的基因递送载体，以促进骨质疏松性骨骨折的愈合，以及对有骨折风险的骨骼进行预防性治疗。拟议的技术来自材料科学和基因转移的融合，前者使用Angstom Medica的专业知识，后者使用哈佛医学院分子整形外科中心的专业知识。 该项目的中心假设是，NCAP材料可以(1)在骨质疏松部位提供局部机械稳定性，(2)有效和高效地运送携带骨再生基因的载体，以提高骨质疏松性骨折的愈合率和愈合骨的力学性能。要发生这种现象，NCAP底物应该(I)可持续地和(Ii)可控制地以局部和靶向的方式释放基因递送载体。通过这种靶向和受控的载体释放，基因将被传递到当地的成骨细胞，增强它们分化为成骨细胞的能力，并在容易发生骨质疏松性骨折的区域合成新骨。NCAP还将起到促进成骨的支架作用，最终将被宿主骨吸收和取代。 要证明这项技术的可行性，必须满足两个基本要求：第一，将载体与NCAP相关联的方法，以允许高效、持续的基因转移到相邻细胞；第二，通过这些方法转移适当的基因时，必须促进骨的形成。这两项要求都将在拟议的调查中进行仔细审查。体外试验将被用来开发将载体与NCAP适当结合的方法。采用大鼠股骨缺损模型的体内试验将被用来确定增强的骨形成。 因此，具体目标是： 1.通过改变NCAP载体的密度、孔大小和表面化学，建立将NCAP和AAV与NCAP结合并控制基因传递的方法。 2.评价NCAP载体构建物在体内增强成骨反应的能力。

DESCRIPTION (provided by applicant): Osteoporosis is a major and growing health care problem that responds inadequately to standard pharmacologic therapy. Because of its low bone mineral density, osteoporotic bone is mechanically weak and fractures more easily than normal bone. Moreover, fracture repair is compromised in osteoporotic patients. The work described in this Phase I STTR proposal aims to develop a gene delivery vector laden nanostructured calcium phosphate (nCaP) substrate for improving the healing of fractures in osteoporotic bone, as well as a prophylactic treatment for bones that are at risk fracture. The proposed technologies emerge from a fusion of materials science, using expertise available at Angstom Medica, and gene transfer, using expertise available at the Center for Molecular Orthopaedics, Harvard Medical School. The central hypothesis of this project is that a nCaP material can (1) provide mechanical stability locally at a site of osteoporosis and (2) effectively and efficiently deliver vectors carrying osteoregenerative genes to improve the rate of healing of osteoporotic fractures and the mechanical properties of the healed bone. For this phenomena to occur, the nCaP substrate should (i) sustainably and (ii) controllably release gene delivery vectors in a localized and targeted manner. Through this targeted and controlled vector release, genes will be delivered to local osteoprogenitor cells, enhancing their ability to differentiate into osteoblasts and synthesize new bone in areas prone to osteoporotic fractures. The nCaP will also behave as a scaffold to encourage osteogenesis and, eventually, will be resorbed and replaced by host bone. Two fundamental requirements must be fulfilled to demonstrate feasibility of this technology: First, methods for associating vectors with nCaP in such a way as to permit efficient, sustained gene transfer to adjacent cells must be developed Second, enhanced formation of bone when the appropriate genes are transferred by these methods must occur. Both of these requirements will be scrutinized in the proposed investigations. In vitro assays will be used to develop methods for associating the vectors appropriately with the nCaP. In vivo assays, employing a rat femoral defect model, will be used to determine enhanced bone formation. Thus the Specific Aims are: 1. To develop processes for associating plasmid DNA and AAV with nCaP and controlling gene delivery by altering the density, pore size and surface chemistry of the nCaP-vector construct. 2. To evaluate the ability of nCaP-vector constructs to enhance osteogenic responses in vivo.