Gugala Zbigniew, Davis Alan R, Fouletier-Dilling Christine M, Gannon Francis H, Lindsey Ronald W, Olmsted-Davis Elizabeth A
Department of Orthopaedic Surgery, Baylor College of Medicine, Houston, TX, USA.
Biomaterials. 2007 Oct;28(30):4469-79. doi: 10.1016/j.biomaterials.2007.07.007. Epub 2007 Jul 23.
Adenovirus BMP2 gene therapy has potential of a robust endogenous BMP2 production, while circumventing many of the problems currently associated with recombinant BMP2. The study objective was to determine and compare the ability of adenovirus BMP2 ex vivo gene therapy in combination with three types of collagen carriers to release BMP2 in vitro and to induce heterotopic bone formation in vivo. Human CD45-negative bone marrow cells were ex vivo transduced with a chimeric Ad5F35BMP2. The bioactivity of BMP2 produced by the transduced cells without a carrier, or in combination with three types of collagen carriers (injectable gel, microporous sponge, collagen-mineral composite) was measured and compared to rhBMP2. The heterotopic osteoinductivity assay was performed in immunocompromised NOD/SCID mice. A statistically significant decrease in the amount of rhBMP2 and adenoviral BMP2 released in vitro from the collagen-mineral composite carrier was noted (21% and 12%, respectively), whereas the amounts of rhBMP2 and adenoviral BMP2 released from the gel or sponge carriers were comparable. In vivo, 14 days post-implantation, no bone was formed consistently in groups with the empty Ad5F35HM4 control vector. New bone formation was evident radiographically and histologically in all groups with the Ad5F35BMP2-transduced cells irrespective of the presence or absence of a carrier. The presence of a carrier resulted in osteogenesis limited to the implantation site, and was most pronounced for solid (sponge, composite) carriers. The physical characteristics of the carrier determined the new bone spatial distribution at the site. Solid carriers reduced the clearance of AD5F35-transduced cells by the host immune cells. Adenoviral ex vivo BMP2 gene therapy in combination with collagen carriers with distinct physical characteristics offers the prospects of adjusting this approach to optimally match the specific therapeutic requirements.
腺病毒BMP2基因疗法具有强大的内源性BMP2生成潜力，同时规避了目前与重组BMP2相关的许多问题。本研究的目的是确定并比较腺病毒BMP2体外基因疗法与三种类型的胶原蛋白载体联合使用时在体外释放BMP2以及在体内诱导异位骨形成的能力。人CD45阴性骨髓细胞用嵌合Ad5F35BMP2进行体外转导。测量转导细胞在无载体或与三种类型的胶原蛋白载体（可注射凝胶、微孔海绵、胶原-矿物质复合物）联合使用时产生的BMP2的生物活性，并与重组人骨形态发生蛋白2（rhBMP2）进行比较。在免疫缺陷的NOD/SCID小鼠中进行异位骨诱导试验。注意到从胶原-矿物质复合物载体体外释放的rhBMP2和腺病毒BMP2的量有统计学意义的下降（分别为21%和12%），而从凝胶或海绵载体释放的rhBMP2和腺病毒BMP2的量相当。在体内，植入后14天，空Ad5F35HM4对照载体组未持续形成骨。无论是否存在载体，所有用Ad5F35BMP2转导细胞的组在影像学和组织学上均可见新骨形成。载体的存在导致成骨作用局限于植入部位，对于固体（海绵、复合物）载体最为明显。载体的物理特性决定了该部位新骨的空间分布。固体载体减少了宿主免疫细胞对AD5F35转导细胞的清除。腺病毒体外BMP2基因疗法与具有不同物理特性的胶原蛋白载体联合使用，为调整该方法以最佳匹配特定治疗需求提供了前景。
