ERK5在小鼠骨质疏松性骨折愈合过程中作用的实验研究

目的通过构建小鼠骨质疏松骨折模型,研究ERK5在骨质疏松性骨折愈合过程中的作用。方法将108只6周龄雌性昆明小鼠随机分成4组,通过手术切除小鼠双侧卵巢及小鼠股骨离断分别构建骨质疏松(OVX)和骨折模型(Fracture),然后给实验组小鼠每日腹腔注射ERK5特异性阻断剂XMD8-92,于1 w、2 w、4 w后分别处死一定数量的小鼠,取术侧股骨标本,行X线片检查、股骨骨痂Micro-CT、HE染色及免疫组织化学染色检查,观察骨折端骨小梁生长情况,骨痂内成骨相关蛋白及ERK5表达情况。结果给予实验小鼠注射XMD8-92后第2周及第4周,Fracture组小鼠骨痂生长较快,骨小梁数目较多,厚度较大,成骨相关蛋白ALP、Runx2的表达相对较多(P0.05),而Fracture+XMD8-92组小鼠骨痂生长则相对缓慢,骨小梁稀少且绯薄,结构相对较乱,碱性磷酸酶(alkaline phosphatase,ALP)、Runx2表达较少(P0.05);且OVX+Fracture+XMD8-92组小鼠与OVX+Fracture组小鼠相比,骨小梁生成更少且紊乱,骨痂生长明显延迟,ALP、Runx2表达量显著减少(P0.05)。结论 ERK5影响骨折端骨痂形成的速度和质量,在促进骨质疏松性骨折愈合过程中起着十分重要的生理作用。

Study of ERK5 in the healing process of osteoporotic fracture in mice

Objective To study the role of ERK5 in the healing process of osteoporotic fractures by establishing osteoporotic fracture model in mice. Methods 108 6-week-old female mice were randomly divided into 4 groups. Osteoporosis and fracture models were established by surgically resecting the bilateral ovaries and cutting off the femur. Then the experimental mice were injected with ERK5-specific blocker XMD8-92 intraperitoneally, and a certain number of mice were sacrificed at the 1st, 2nd and 4th week. X-ray examination, Micro-CT, HE staining and immunohistochemically staining of bone callus were performed to observe the growth of trabecular bone, and the expression of osteogenesis-related proteins and ERK5. Results The experimental mice were injected with XMD8-92 at the 2nd week and the 4th week. In the fracture group, the callus of mice grew faster, there were more and thicker trabecular bone, and the expression of the osteogenesis-related proteins ALP and Runx-2 was higher (P<0.05). The callus grew much slower with less and thinner trabecular bone, and the expression of the osteogenesis-related proteins ALP and Runx-2 was lower in the fracture+XMD8-92 group (P<0.05). Compared with the osteoporotic fracture group, the osteoporotic fracture + XMD8-92 group showed less and more disordered trabecular bone formation, significant delay in the growth of callus, and significantly lower ALP and Runx-2 expression (P<0.05). Conclusion ERK5 affects the rate and quality of callus formation in the area of fracture and plays an important physiological role in the process of osteoporotic fracture healing.