Zhang Xiao S, Linkhart Thomas A, Chen Shin-Tai, Peng Hairong, Wergedal Jon E, Guttierez Genevieve G, Sheng Matilda H-C, Lau K-H William, Baylink David J
Department of Medicine, Loma Linda University, and Gene Therapy Division, Musculoskeletal Disease Center (151), VA Loma Linda Healthcare Network, Loma Linda, CA 92357, USA.
J Gene Med. 2004 Jan;6(1):4-15. doi: 10.1002/jgm.477.
Bone loss in osteoporosis is caused by an imbalance between resorption and formation on endosteal surfaces of trabecular and cortical bone. We investigated the feasibility of increasing endosteal bone formation in mice by ex vivo gene therapy with bone marrow stromal cells (MSCs) transduced with a MLV-based retroviral vector to express human bone morphogenetic protein 4 (BMP4).
We assessed two approaches for administering transduced MSCs. beta-Galactosidase (beta-Gal) transduced C57BL/6J mouse MSCs were injected intravenously via tail vein or directly injected into the femoral bone marrow cavity of non-marrow-ablated syngenic recipient mice and bone marrow cavity engraftment was assessed. BMP4- or beta-Gal-transduced cells were injected into the femoral bone marrow cavity and effects on bone were evaluated by X-ray, peripheral quantitative computed tomography (pQCT), and histology.
After tail-vein injection less than 20% of recipient mice contained beta-Gal-positive donor cells in femur, humerus or vertebra marrow cavities combined, and in these mice only 0.02-0.29% of injected cells were present in the bone marrow. In contrast, direct intramedullary injection was always successful and an average of 2% of injected cells were present in the injected femur marrow cavity 24 hours after injection. Numbers of donor cells decreased over the next 14 days. Intramedullary injection of BMP4-transduced MSCs induced bone formation. Trabecular bone mineral density (BMD) determined by pQCT increased 20.5% at 14 days and total BMD increased 6.5% at 14 days and 10.4% at 56 days.
The present findings support the feasibility of using ex vivo MSC-based retroviral gene therapy to induce relatively sustained new bone formation, with normal histological appearance, at endosteal bone sites.
骨质疏松症中的骨质流失是由小梁骨和皮质骨内骨膜表面的吸收与形成失衡所致。我们研究了通过用基于莫洛尼氏鼠白血病病毒（MLV）的逆转录病毒载体转导骨髓基质细胞（MSC）以表达人骨形态发生蛋白4（BMP4）进行离体基因治疗来增加小鼠内骨膜骨形成的可行性。
我们评估了两种给予转导后的MSC的方法。将β-半乳糖苷酶（β-Gal）转导的C57BL/6J小鼠MSC经尾静脉静脉注射或直接注射到未进行骨髓消融的同基因受体小鼠的股骨髓腔内，并评估骨髓腔内的植入情况。将BMP4或β-Gal转导的细胞注射到股骨髓腔内，并通过X射线、外周定量计算机断层扫描（pQCT）和组织学评估对骨的影响。
尾静脉注射后，不到20%的受体小鼠在股骨、肱骨或椎骨髓腔中联合含有β-Gal阳性供体细胞，并且在这些小鼠中，仅0.02 - 0.29%的注射细胞存在于骨髓中。相比之下，直接髓内注射总是成功的，并且在注射后24小时，平均2%的注射细胞存在于注射的股骨髓腔中。在接下来的14天内供体细胞数量减少。髓内注射BMP4转导的MSC诱导骨形成。通过pQCT测定的小梁骨矿物质密度（BMD）在14天时增加了20.5%，总BMD在14天时增加了6.5%，在56天时增加了10.4%。
目前的研究结果支持使用基于离体MSC的逆转录病毒基因治疗在内骨膜骨部位诱导相对持续的新骨形成且具有正常组织学外观的可行性。
