Boden S D, Titus L, Hair G, Liu Y, Viggeswarapu M, Nanes M S, Baranowski C
Department of Orthopaedic Surgery, Emory University School of Medicine, Atlanta, Georgia, USA.
Spine (Phila Pa 1976). 1998 Dec 1;23(23):2486-92. doi: 10.1097/00007632-199812010-00003.
A posterior arthrodesis animal model using local expression of a newly discovered osteoinductive protein delivered in bone marrow cells.
To introduce the concept of local gene therapy and determine its feasibility for achieving lumbar spine fusion using a gene for a novel osteoinductive protein: LIM Mineralization Protein-1 (LMP-1).
Extensive work is currently underway to improve the healing success and morbidity associated with the gold standard bone-grafting material of autogenous iliac crest. As a result, alternative osteoinductive proteins and new delivery methods warrant investigation. The authors' laboratory recently identified a novel gene that had osteoinductive capacity in vitro and is therefore a candidate for a new in vivo osteoinductive agent.
Single-level posterior lumbar and thoracic arthrodesis was attempted in 14 athymic rats. The graft material, which consisted of a devitalized bone matrix (no osteoinductive activity) soaked with 0.75 to 1.5 million bone marrow cells, was inserted with the dorsal spine exposed. In each rat, one site received marrow cells transfected with the cDNA encoding a novel osteoinductive protein. At the other site for a control, the marrow cells were transfected with the reverse copy of the cDNA that did not express any protein. Transfection of marrow cells for 2 hours was accomplished using the mammalian expression vector pCMV2. Rats were killed after 4 weeks, and the spines were evaluated by manual palpation, radiographs, and nondecalcified histology.
In the pivotal experiment, successful spine fusion was obtained in 9/9 (100%) of the sites receiving marrow cells transfected with the active LMP-1 cDNA and in 0/9 (0%) of the sites receiving marrow cells transfected with the reverse (inactive) LMP-1 cDNA. Radiographs and histology confirmed the manual palpation results, demonstrating controlled new bone formation in the carrier and marrow transfected with the active LMP-1 cDNA and essentially no bone induction in the sites treated with marrow cells that did not express the protein.
These data confirm that local delivery of the novel LMP-1 cDNA using bone marrow cells is feasible in vivo. Furthermore, these results demonstrate that posterior thoracic or lumbar spine fusion can be achieved in rats by local delivery of the LMP-1 cDNA.
一种后关节融合动物模型，利用在骨髓细胞中递送新发现的骨诱导蛋白的局部表达。
引入局部基因治疗的概念，并确定使用新型骨诱导蛋白基因：LIM矿化蛋白-1（LMP-1）实现腰椎融合的可行性。
目前正在进行大量工作，以提高与自体髂嵴这一金标准骨移植材料相关的愈合成功率和发病率。因此，替代的骨诱导蛋白和新的递送方法值得研究。作者的实验室最近鉴定出一种在体外具有骨诱导能力的新基因，因此是一种新的体内骨诱导剂的候选基因。
对14只无胸腺大鼠尝试进行单节段腰椎和胸椎后关节融合。将由失活骨基质（无骨诱导活性）浸泡0.75至150万个骨髓细胞组成的移植材料在暴露背侧脊柱的情况下插入。在每只大鼠中，一个部位接受用编码新型骨诱导蛋白的cDNA转染的骨髓细胞。在另一个作为对照的部位，骨髓细胞用不表达任何蛋白质的cDNA反向拷贝转染。使用哺乳动物表达载体pCMV2完成骨髓细胞2小时的转染。4周后处死大鼠，通过手动触诊、X线片和未脱钙组织学评估脊柱。
在关键实验中，接受用活性LMP-1 cDNA转染的骨髓细胞的部位9/9（100%）成功实现脊柱融合，而接受用反向（无活性）LMP-1 cDNA转染的骨髓细胞的部位0/9（0%）成功实现脊柱融合。X线片和组织学证实了手动触诊结果，表明在用活性LMP-1 cDNA转染的载体和骨髓中有可控的新骨形成，而在用不表达该蛋白质的骨髓细胞处理的部位基本没有骨诱导。
这些数据证实了使用骨髓细胞局部递送新型LMP-1 cDNA在体内是可行的。此外，这些结果表明通过局部递送LMP-1 cDNA可在大鼠中实现胸椎或腰椎后关节融合。
