Kostenuik Paul J, Bolon Brad, Morony Sean, Daris Mark, Geng Zhaopo, Carter Christopher, Sheng Jackie
Department of Pathology, Amgen, Thousand Oaks, CA 91320-1799, USA.
Bone. 2004 Apr;34(4):656-64. doi: 10.1016/j.bone.2003.12.006.
Osteoporosis is a chronic condition that is typically treated by the long-term repeated administration of antiresorptive agents. Gene therapy has the potential to deliver protein-based antiresorptive agents without the need for repeated administration. Osteoprotegerin (OPG) is a naturally occuring protein that prevents bone resorption by inhibiting osteoclast formation, function and survival. We tested whether adeno-associated virus (AAV) could deliver OPG at levels that are sufficient to reverse established osteopenia in ovariectomized (OVX) mice without causing liver toxicity. Tibial bone mineral density (BMD) was measured by peripheral quantitative computed tomography (pQCT) in 12-week-old CDF1 mice prior to OVX or sham surgery. Six weeks later, BMD was significantly reduced in OVX mice compared to sham controls or pre-surgery values. Sham and OVX mice were then injected once IV with an AAV vector carrying cDNA for recombinant hOPG (AAV-OPG) or beta-galactosidase (AAV-betaGal). BMD and bone histomorphometry were assessed 10 weeks after treatment. A single injection of AAV-OPG led to the appearance of human OPG (hOPG) in the serum of mice within 7 days, and high serum levels of hOPG were maintained for the duration of the 10-week study. At the end of the study, OVX mice given AAV-OPG had significantly greater tibial BMD compared to age-matched OVX animals given AAV-betaGal. In sham-operated mice, AAV-OPG also significantly increased tibial BMD compared to AAV-betaGal. The increased BMD in AAV-OPG animals was accompanied by significantly increased bone volume and significantly reduced osteoclast surfaces in the proximal tibial metaphysis. Liver histology was normal, and circulating activities of hepatocyte cytosolic enzymes were unaffected by AAV exposure. In an accompanying experiment, young (3-4 weeks) C57BL/6 mice treated once IV with AAV-OPG maintained pharmacologically active levels of OPG in serum for at least 16 months. In summary, a single AAV-OPG treatment reversed established osteopenia in OVX mice without evidence of liver toxicity. AAV delivery appears to be a safe and effective method for producing sustained systemic exposure to OPG.
骨质疏松症是一种慢性疾病，通常通过长期反复给予抗吸收药物进行治疗。基因治疗有潜力递送基于蛋白质的抗吸收药物，而无需反复给药。骨保护素（OPG）是一种天然存在的蛋白质，通过抑制破骨细胞的形成、功能和存活来防止骨吸收。我们测试了腺相关病毒（AAV）能否以足以逆转去卵巢（OVX）小鼠已有的骨质减少且不引起肝毒性的水平递送OPG。在12周龄的CDF1小鼠进行OVX手术或假手术之前，通过外周定量计算机断层扫描（pQCT）测量胫骨骨矿物质密度（BMD）。六周后，与假手术对照组或术前值相比，OVX小鼠的BMD显著降低。然后，对假手术和OVX小鼠静脉注射一次携带重组人OPG（hOPG）cDNA的AAV载体（AAV-OPG）或β-半乳糖苷酶（AAV-βGal）。治疗10周后评估BMD和骨组织形态计量学。单次注射AAV-OPG导致小鼠血清中在7天内出现人OPG（hOPG），并且在为期10周的研究期间血清中hOPG水平一直维持在较高水平。在研究结束时，与给予AAV-βGal的年龄匹配的OVX动物相比，给予AAV-OPG的OVX小鼠胫骨BMD显著更高。在假手术小鼠中，与AAV-βGal相比，AAV-OPG也显著增加了胫骨BMD。AAV-OPG处理动物的BMD增加伴随着胫骨近端干骺端骨体积显著增加和破骨细胞表面显著减少。肝脏组织学正常，肝细胞胞质酶的循环活性不受AAV暴露的影响。在一项伴随实验中，静脉注射一次AAV-OPG的年轻（3 - 4周）C57BL/6小鼠血清中OPG的药理活性水平维持至少16个月。总之，单次AAV-OPG治疗可逆转OVX小鼠已有的骨质减少，且无肝毒性证据。AAV递送似乎是一种安全有效的方法，可使机体持续全身性暴露于OPG。
