Low‐magnitude high‐frequency vibration enhances gene expression related to callus formation,mineralization and remodeling during osteoporotic fracture healing in rats

Low magnitude high frequency vibration (LMHFV) has been shown to improve anabolic and osteogenic responses in osteoporotic intact bones and during osteoporotic fracture healing; however, the molecular response of LMHFV during osteoporotic fracture healing has not been investigated. It was hypothesized that LMHFV could enhance osteoporotic fracture healing by regulating the expression of genes related to chondrogenesis (Col‐2), osteogenesis (Col‐1) and remodeling (receptor activator for nuclear factor‐ κ B ligand (RANKL) and osteoproteger (OPG)). In this study, the effects of LMHFV on both osteoporotic and normal bone fracture healing were assessed by endpoint gene expressions, weekly radiographs, and histomorphometry at weeks 2, 4 and 8 post‐treatment. LMHFV enhanced osteoporotic fracture healing by up‐regulating the expression of chondrogenesis‐, osteogenesis‐ and remodeling‐related genes (Col‐2 at week 4 (p = 0.008), Col‐1 at week 2 and 8 (p < 0.001and p = 0.008) and RANKL/OPG at week 8 (p = 0.045)). Osteoporotic bone had a higher response to LMHFV than normal bone and showed significantly better results as reflected by increased expression of Col‐2 and Col‐1 at week 2 (p < 0.001 for all), larger callus width at week 2 (p = 0.001), callus area at week 1 and 5(p < 0.05 for all) and greater relative area of osseous tissue (p = 0.002) at week 8. This study helps to understand how LMHFV regulates gene expression of callus formation, mineralization and remodeling during osteoporotic fracture healing. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1572–1579, 2014.     

Distinct frequency dependent effects of whole‐body vibration on non‐fractured bone and fracture healing in mice

Low‐magnitude high‐frequency vibration (LMHFV) provokes anabolic effects in non‐fractured bone; however, in fracture healing, inconsistent results were reported and optimum vibration conditions remain unidentified. Here, we investigated frequency dependent effects of LMHFV on fracture healing. Twelve‐week‐old, female C57BL/6 mice received a femur osteotomy stabilized using an external fixator. The mice received whole‐body vibrations (20 min/day) with 0.3g peak‐to‐peak acceleration and a frequency of either 35 or 45 Hz. After 10 and 21 days, the osteotomized femurs and intact bones (contra‐lateral femurs, lumbar spine) were evaluated using bending‐testing, µ‐computed tomography, and histomorphometry. In non‐fractured trabecular bone, vibration with 35 Hz significantly increased the relative amount of bone (+28%) and the trabecular number (+29%), whereas cortical bone was not influenced. LMHFV with 45 Hz failed to provoke anabolic effects in trabecular or cortical bone. Fracture healing was not significantly influenced by whole‐body vibration with 35 Hz, whereas 45 Hz significantly reduced bone formation (?64%) and flexural rigidity (?34%) of the callus. Although the exact mechanisms remain open, our results suggest that small vibration setting changes could considerably influence LMHFV effects on bone formation in remodeling and repair, and even disrupt fracture healing, implicating caution when treating patients with impaired fracture healing. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1006–1013, 2014.

     

Administration duration influences the effects of low‐magnitude,high‐frequency vibration on ovariectomized rat bone

Low‐magnitude, high‐frequency vibration (LMHFV) has been proposed as a non‐drug anti‐osteoporosis treatment. However, the influence of administration duration on its effect is seldom investigated. In this study, the effect of 16‐week LMHFV (0.3 g, 30 Hz, 20 min/day) on the bone mineral densities (BMDs), bone mechanical properties, and cellular responses of osteoporotic and healthy rats was examined by in vivo peripheral quantitative computed tomography (pQCT), fracture tests, cell assays, and mRNA quantification. Forty‐eight adult rats were equally assigned to sham surgery (SHM), sham surgery with LMHFV (SHM+V), ovariectomy (OVX), and ovariectomy with LMHFV (OVX+V) groups. At week 8, LMHFV ameliorated ovariectomy‐induced deterioration of trabecular bone, with a significantly higher tibia trabecular BMD (+11.2%) being noted in OVX+V rats (vs. OVX). However, this positive effect was not observed at later time points. Furthermore, 16 weeks of LMHFV caused significant reductions in the vertebral mean BMD (?13.0%), trabecular BMD (?15.7%), and maximum load (?21.5%) in OVX+V rats (vs. OVX). Osteoblasts derived from osteoporotic rat bone explants showed elevated BSP and OSX mRNA expression induced by LMHFV on day 1. However, no further positive effect on osteoblastic mRNA expression, alkaline phosphatase activity, or calcium deposition was observed with prolonged culture time. A higher ratio of RANKL/OPG induced by LMHFV suggests that osteoclastogenesis may be activated. Together, these results demonstrate that administration duration played an important role in the effect of LMHFV. Early exposure to LMHFV can positively modulate osteoporotic bone and osteoblasts; however, the beneficial effect seems not to persist over time. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1147–1157, 2016.

     

Low‐magnitude high‐frequency vibration accelerates callus formation,mineralization, and fracture healing in rats

Fracture healing is a biological regenerative process that follows a well‐orchestrated sequence. Most healing is uneventful and enhancement of normal fracture healing is not commonly done, although it is clinically important in the recovery and regain of functions after fracture. This study investigated the osteogenic effect of low‐magnitude high‐frequency vibration (LMHFV, 35 Hz, 0.3 g) on the enhancement of fracture healing in rats with closed femoral shaft fracture by comparing with sham‐treated control. Assessments with plain radiography, micro‐CT as well as histomorphometry showed that the amount of callus was significantly larger (p = 0.001 for callus area, 2 weeks posttreatment); the remodeling of the callus into mature bone was significantly faster (p = 0.039, 4 weeks posttreatment) in the treatment group. The mechanical strength of the healed fracture in the treatment group at 4 weeks was significantly greater (p < 0.001). The results showed the acceleration of callus formation, mineralization, and fracture healing in the treatment group. It is concluded that LMHFV enhances healing in the closed femoral shaft fracture in rats. The potential clinical advantages shall be confirmed in the subsequent clinical trials. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 458–465, 2009     

Low intensity pulsed ultrasound enhances fracture healing in both ovariectomy‐induced osteoporotic and age‐matched normal bones

Low intensity pulsed ultrasound (LIPUS) was proven to enhance fracture healing effectively. Similar effect of LIPUS on accelerating the osteoporotic fracture healing was therefore hypothesized. The normal and osteoporotic fracture healings under this non‐invasive biophysical intervention of LIPUS were compared and investigated. Closed femoral fracture procedures were performed on 120 Sprague–Dawley rats, in which 60 of them were ovariectomized (OVX). The rats were randomly assigned into four groups: sham OVX with treatment (Sham‐T), sham OVX control (Sham‐C), OVX with treatment (OVX‐T) and OXV control (OVX‐C). LIPUS treatment was 20 min a day, 5 days a week for durations of 2, 4, or 8 weeks. Results from weekly radiography, histomorphometry, micro‐computed tomography and mechanical test showed both the treatment groups were with better healing responses than their control groups. Moreover, between the normal and the osteoporotic treatment groups, a significantly higher (p = 0.015) callus width (week 4), higher ratio of increment in bone volume to tissue volume ratio value (7.4% more), faster response of endochondral ossification and a higher stiffness measurement were observed in the osteoporotic treatment group. These comparable results on healing responses imply that LIPUS can be applied clinically to enhance both normal and osteoporotic fracture healing. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:129–136, 2012     

振动力学刺激对骨质疏松性骨折愈合的影响

目的本研究旨在探讨高频率低能量的振动力学刺激对骨质疏松性骨折愈合的影响。方法59只大鼠建立大鼠卵巢切除骨质疏松模型,建模成功后构建股骨骨折模型,并随机分为振动力学刺激组和对照组。骨折后第5天开始对振动组使用高频率低能量振动平台(35Hz,峰振幅0.3重力加速度)行每天20min的振动力学刺激,对照组则行假治疗。每周摄X线片观察骨折愈合的情况,并采用显微计算机断层扫描和生物力学测试评估骨痂生成的情况及其力学属性。结果 X线随访显示,振动组的骨折愈合速度和愈合率均优于对照组。前者新生矿化骨痂的体积在治疗后第2周和第4周时均显著高于后者。第8周时,振动组成熟骨痂的体积以及整体的力学强度均显著优于对照组。结论高频率低能量振动力学刺激可促进骨质疏松性骨折的愈合。     

运用高频率低能量振动促进骨折愈合的实验研究

目的 本研究旨在探讨全身性的高频率低能量振动对骨折愈合的作用.方法 建立大鼠闭合性股骨骨折髓内固定模型(n=55),并随机分为治疗组(n=28)和对照组(n=27).骨折后第5天开始对治疗组使用高频率低能量振动平台(35 Hz,峰振幅0.3 g)治疗,对照组则行假治疗.采用二维(X线)及三维(显微计算机断层扫描)的影像学方法和生物力学测试对骨折愈合的情况进行评估,并行统计学比较分析.结果 治疗后2周治疗组新生的矿化骨痂在上维及三维定量分析中均明显多于对照组,差异有统计学意义(P<0.001和P=0.014).治疗后4周治疗组的骨折愈合率(85.7%)高于对照组(57.1%),骨折愈合的生物力学属性也优于埘照组,差异有统计学意义(P=0.023).结论 高频率低能量振动可刺激骨折部位骨痂的生成及矿化,从而促进骨折愈合.     

Impaired Fracture Healing in Sarco-Osteoporotic Mice Can Be Rescued by Vibration Treatment Through Myostatin Suppression

Sarcopenia is highly prevalent in fragility fracture patients and is associated with delayed healing. In this study, we investigated the effect of low-magnitude high-frequency vibration (LMHFV) on osteoporotic fracture with sarcopenia and the potential role of myostatin. Osteoporotic fractures created in sarcopenic SAMP8, non-sarcopenic SAMR1 were randomized to control or LMHFV (SAMP8, SAMR1, SAMP8-V, or SAMR1-V) groups. Healing and myostatin expression were evaluated at 2, 4, and 6 weeks post-fracture. In vitro, conditioned-media were collected from myofibers isolated from aged and young SAMP8 or C2C12 myoblasts with or without LMHFV. Osteoblastic MC3T3-E1 under osteogenic differentiation were treated with plain or conditioned-medium (±myostatin propeptide). LMHFV significantly enhanced callus formation was in non-sarcopenic SAMR1 mice; but the enhancement effect was not significant in SAMP8 mice at week 2. Myostatin expressions in callus and biceps femoris of SAMP8 group were significantly higher all groups with significant negative correlation with callus size (R² = 0.7256; p = 0.0004). Mechanical properties (week 4) and callus remodeling (week 6) were inferior in SAMP8 versus SAMR1 and were significantly enhanced by LMHFV. Alkaline Phosphatase (ALP) and Runx2 expression of MC3T3-E1 was lower in aged myofiber compared with young, but upregulated by LMHFV or myostatin inhibition; also confirmed with C2C12. LMHFV enhanced early callus formation, microarchitecture, callus remodeling and mechanical properties of fracture healing in both SAMP8 and SAMR1; however, more effective in non-sarcopenic SAMR1 mice. Impaired fracture healing in sarcopenic SAMP8 mice is attributed by elevated myostatin expression in callus and muscle, which correlated negatively with callus formation. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:277-287, 2020     

Effect of Dosing Interval Duration of Intermittent Ibandronate Treatment on the Healing Process of Femoral Osteotomy in a Rat Fracture Model

The effects of bisphosphonate treatment schedule on fracture healing have not previously been tested. We evaluated the effect of ibandronate dosing interval duration on healing following surgical “fracture” (osteotomy) using a rat femoral fracture model. Six-week-old rats (n = 160) underwent osteotomy and were then allocated into vehicle control (CNT) or an ibandronate treatment group: 5 μg/kg daily (DAY, 5 days/week), 75 μg/kg once every 3 weeks (I-3), 150 μg/kg once every 6 weeks (I-6), resulting in the same total ibandronate dose over the study. Rats were killed after 6 or 18 weeks. At 18 weeks, all fracture lines had disappeared in the CNT and I-6 groups; approximately 10% of fracture lines remained in the DAY and I-3 groups. Ibandronate-treated groups showed large callus areas around the fractures, which shrank between 6 and 18 weeks after surgery; the extent of shrinkage decreased with shorter dosing interval. In histomorphometry, callus remodeling was suppressed by ibandronate; this became more apparent at shorter dose intervals. The structural properties of osteotomized femora were increased in the DAY group compared with CNT, but intrinsic material properties reduced inversely and became closer to those of CNT in response to increased dosing interval. Ibandronate induced formation of large calluses around osteotomies but delayed woven bone remodeling into lamellar bone and reduced intrinsic material properties in a rat fracture model. Extending the dosing interval of intermittent ibandronate treatment appeared to reduce the suppression of callus remodeling caused by ibandronate, which would have delayed healing after osteotomy.     

The effect of PTH(1‐34) on fracture healing during different loading conditions

Parathyroid hormone (PTH) and PTH(1‐34) have been shown to promote bone healing in several animal studies. It is known that the mechanical environment is important in fracture healing. Furthermore, PTH and mechanical loading has been suggested to have synergistic effects on intact bone. The aim of the present study was to investigate whether the effect of PTH(1‐34) on fracture healing in rats was influenced by reduced mechanical loading. For this purpose, we used female, 25‐week‐old ovariectomized rats. Animals were subjected to closed midshaft fracture of the right tibia 10 weeks after ovariectomy. Five days before fracture, half of the animals received Botulinum Toxin A injections in the muscles of the fractured leg to induce muscle paralysis (unloaded group), whereas the other half received saline injections (control group). For the following 8 weeks, half of the animals in each group received injections of hPTH(1‐34) (20 µg/kg/day) and the other half received vehicle treatment. Fracture healing was assessed by radiology, dual‐energy X‐ray absorptiometry (DXA), histology, and bone strength analysis. We found that unloading reduced callus area significantly, whereas no effects of PTH(1‐34) on callus area were seen in neither normally nor unloaded animals. PTH(1‐34) increased callus bone mineral density (BMD) and bone mineral content (BMC) significantly, whereas unloading decreased callus BMD and BMC significantly. PTH(1‐34) treatment increased bone volume of the callus in both unloaded and control animals. PTH(1‐34) treatment increased ultimate force of the fracture by 63% in both control and unloaded animals and no interaction of the two interventions could be detected. PTH(1‐34) was able to stimulate bone formation in normally loaded as well as unloaded intact bone. In conclusion, the study confirms the stimulatory effect of PTH(1‐34) on fracture healing, and our data suggest that PTH(1‐34) is able to promote fracture healing, as well as intact bone formation during conditions of reduced mechanical loading. © 2013 American Society for Bone and Mineral Research.     

Effects of α‐tocopherol on the early phase of osteoporotic fracture healing

Fracture healing is a complex process, which is more complicated if the bone is osteoporotic. One of the vitamin E isomers, α‐tocopherol, has been found to prevent osteoporosis and improve bone fracture healing but its role in the healing of osteoporotic fractures is still unclear. We carried out a study on the effects of α‐tocopherol supplementation on osteoporotic fracture healing using an ovariectomized rat model, whereby we focused on the early phase of fracture healing, that is, the phase with excessive production of free radicals. Twenty‐four female Sprague–Dawley rats were divided into three groups: sham‐operated (SO), ovariectomized–control (OVC), and ovariectomized + α‐tocopherol supplementation (ATF) groups. The right femora of all the rats were fractured at mid‐diaphysis and K‐wires were inserted for internal fixation. After 2 weeks of treatment, the rats were euthanized and the femora were dissected out for measurement of callous volume by CT‐scan and radiological staging of callous formation and fracture healing. The oxidative parameters of the fractured femora were also measured. The results showed that the callous volume and callous staging were not different between the groups. However, the fracture healing stage of the OVC group was lower than the SO group, while α‐tocopherol supplementation in the ATF group had improved the healing until it was comparable to the SO group. The activities of the anti‐oxidatant enzymes, superoxide dismutase, and glutathione peroxidase in the ATF group were found to be significantly higher than in the OVC group. In conclusion, α‐tocopherol improved fracture healing but had no effect on the callous volume and staging. The improvement in fracture healing may be due to the increased activities of the anti‐oxidatant enzymes in the bone during the early phase of fracture healing of osteoporotic bone. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1732–1738, 2011     

Effect of osteoporosis medications on fracture healing

Antiosteoporotic medications are often used to concurrently treat a patient’s fragility fractures and underlying osteoporosis. This review evaluates the existing literature from animal and clinical models to determine these drugs’ effects on fracture healing. The data suggest that these medications may enhance bone healing, yet more thorough prospective studies are warranted. Pharmacologic agents that influence bone remodeling are an essential component of osteoporosis management. Because many patients are first diagnosed with osteoporosis when presenting with a fragility fracture, it is critical to understand how osteoporotic medications influence fracture healing. Vitamin D and its analogs are essential for the mineralization of the callus and may also play a role in callus formation and remodeling that enhances biomechanical strength. In animal models, antiresorptive medications, including bisphosphonates, denosumab, calcitonin, estrogen, and raloxifene, do not impede endochondral fracture healing but may delay repair due to impaired remodeling. Although bisphosphonates and denosumab delay callus remodeling, they increase callus volume and result in unaltered biomechanical properties. Calcitonin increases cartilage formation and callus maturation, resulting in improved biomechanical properties. Parathyroid hormone, an anabolic agent, has demonstrated promise in animal models, resulting in accelerated healing with increased callus volume and density, more rapid remodeling to mature bone, and improved biomechanical properties. Clinical data with parathyroid hormone have demonstrated enhanced healing in distal radius and pelvic fractures as well as postoperatively following spine surgery. Strontium ranelate, which may have both antiresorptive and anabolic properties, affects fracture healing differently in normal and osteoporotic bone. While there is no effect in normal bone, in osteoporotic bone, strontium ranelate increases callus bone formation, maturity, and mineralization; forms greater and denser trabeculae; and improves biomechanical properties. Further clinical studies with these medications are needed to fully understand their effects on fracture healing in order to simultaneously treat fragility fractures and underlying osteoporosis.     

骨质疏松性骨折实验模型的设计与建立

目的：建立较理想的骨质疏松性骨折实验模型，方法：SD大鼠60只，8月龄，雌性，手术方法：切除双侧卵巢；术后3个月，手术造成股骨中段骨折，进行骨圆针髓腔内固定。模型建立前后双能X线骨密度仪（DEXA），组织学、放射学等动态观察。结果：卵巢切除3个月后DEXA检测结果与术前比较：全身骨密度明显降低（P＜0．02）；子宫内膜组织萎缩变薄，内膜内腺体消失或萎缩，变性呈空泡状；软骨内成骨与膜内成骨共同参与了骨质疏松性骨折的修复，且以软骨内成骨为主，与一般骨折愈合方式相似，模型动物骨折愈合过程中，软骨内成骨延缓，骨性骨痂改建（骨吸收＞骨形成）加速，骨痂内胶原纤维疏松，排列紊乱，与主应力方向不一致，放射学观察模型动物骨折位置，类型统一，内固定后骨折断端稳定。结论：本实验建立的骨质疏松性骨折动物模型模型其方法，易于复制，可应用于骨质疏松林骨折的相关研究。     

Zoledronic acid suppresses callus remodeling but enhances callus strength in an osteoporotic rat model of fracture healing

Mini-abstractIn this study, we demonstrated that the use of zoledronic acid does not impair fracture healing, but results in superior callus size and resistance at the fracture site, which could be the consequence of a lower rate of bone turnover due to its anti-catabolic effect.ObjectiveTo investigate the effect of inhibition of bone remodeling by the bisphosphonate, zoledronic acid, on callus properties in an osteoporotic rat model of fracture healing.MethodsOvariectomized (OVX) rats were randomly divided into four treatment groups (n = 24 per group): saline control (CNT); and three systemic zoledronic acid-injected groups (0.1 mg/kg), administered 1 day (ZOLD1), 1 week (ZOLW1), and 2 weeks (ZOLW2) after fracture. Rats were killed at either 6 or 12 weeks postoperatively. Postmortem analyses included radiography, microcomputed tomography, histology, histomorphometry, biomechanical tests, and nanoindentation tests.ResultsTreatment with zoledronic acid led to a significant increase in trabecular bone volume within the callus, as well as in callus resistance, compared to those in the saline control rats; delayed administration (ZOLW2) reduced intrinsic material properties, including ultimate stress and elastic modulus, and microarchitecture parameters, including bone volume/total volume (BV/TV), trabecular thickness (Tb.Th), and connectivity density (Conn.D), compared with ZOLD1 at 12 weeks after surgery. OVX had a negative effect on the progression of endochondral ossification at 6 weeks. Zoledronic acid administration at an early stage following fracture may bind to early callus, and thus not affect subsequent callus formation and endochondral ossification, while delayed administration (ZOLW2) mildly suppresses bony callus remodeling.ConclusionThe superior results obtained with zoledronic acid (ZOLD1, ZOLW1, and ZOLW2) compared to CNT in terms of callus size and resistance could be the consequence of a lower rate of bone turnover at the fracture site due to the anti-catabolic effect of zoledronic acid. Mild suppression of callus remodeling by delayed administration did not impair the initial phase of the fracture healing process.     

Osteoporosis influences the early period of fracture healing in a rat osteoporotic model

Osteoporotic fractures commonly occur in the elderly. Although current therapies are aimed at the prevention and treatment of osteoporotic fractures, studies examing the fracture healing process in osteoporotic bone are limited. We produced an osteoporotic rat model by ovariectomy (ovx) and maintained a low calcium diet (LCD) in order to evaluate the influence of osteoporosis on fracture healing. Callus formation and strength was monitored over a 3 week period by histological and biomechanical assessment. Data collected simultaneously on a group of rats undergoing sham surgery (sx) were used for comparison. A 40% reduction in fracture callus cross-sectional area and a 23% reduction in bone mineral density in the healing femur of the ovx rats was observed on day 21 following fracture as compared with the sx group (p < 0.01). Biomechanical data from the healing femur of the ovx rats revealed a fivefold decrease in the energy required to break the fracture callus, a threefold decrease in peak failure load, a twofold decrease in stiffness and a threefold decrease in stress as compared with the sx group (p < 0.01, respectively). Histomorphological analysis revealed a delay in fracture callus healing with poor development of mature bone in the ovx rats. This study provides physical evidence of altered fracture healing in osteoporotic bone, which may have important implications in evaluating the effects of new treatments for osteoporosis on fracture healing.     

骨质疏松性骨折愈合与骨量、骨结构及力学性能相关性的实验研究

目的探明骨质疏松性骨折愈合程度与骨量、骨结构与力学性能的相互关系,以期能为临床治疗提供科学指导与理论依据.方法选择8月龄雌性SPF级SD大鼠130只,随机分为2组：骨质疏松性骨折组（OPFM）与一般性骨折组（CFM）,每组各65只.手术方法建立骨质疏松性骨折与一般性骨折的实验模型,于术后1、2、4、6、8、12、16周作骨痂组织形态计量学、骨密度与力学性能测试等观察.结果①骨痂组织骨组织形态计量学结果发现：OPFM组成熟小梁骨占骨痂面积比CFM组小,且小梁骨厚度变薄、小梁骨间距较宽;同时骨小梁动力学参数显示：OPFM组骨小梁表面荧光标记百分比（LS）较CFM组低,而骨矿化沉积率（MAR）却较高.②骨密度（BMD）测定显示：两组BMD值8周时均达到高峰（P＞0.5）,随后均降低,OPFM组下降尤为明显;12周时两组间差异有显著性（P＜0.05）.③骨痂组织扭转力学强度测试结果表明：8、12周OPFM组扭转强度均较CFM组低.结论在骨质疏松性骨折修复过程中,骨痂组织的有机成份组成、显微结构、骨矿代谢与骨量的异常改变导致了其力学强度乃至骨折愈合质量的降低,是再次骨折发生的主要原因.     

富血小板血浆联合人脐带间充质干细胞移植对大鼠骨质疏松骨折愈合的影响

目的探讨PRP联合h UC-MSCs移植对大鼠骨质疏松性骨折愈合的影响。方法雌性SPF级SD大鼠50只随机分为5组,每组10只:假手术组(仅切除卵巢周围组织),安慰剂组(注射生理盐水),未诱导组(给予未诱导的h UC-MSCs),成骨诱导组(移植诱导后的h UC-MSCs),PRP+成骨诱导组(移植诱导后的h UC-MSCs联合PRP)。OPF造模成功后,对各组动物进行细胞移植3次,分别在OPF造模后1周、3周和7周。骨折后的第1周、3周、5周、7周、11周、13周Micro CT扫描动物模型患肢。结果 Micro CT动态观察结果显示,PRP+成骨诱导组骨痂生成量明显多于、早于其余各组,骨折11周时达到临床愈合标准,而其他组别骨痂重塑期相对滞后,比正常骨量大鼠愈合时间至少推迟了37.5%。结论 PRP联合h UC-MSCs移植可促进大鼠骨质疏松性骨折愈合,为临床治疗OPF提供数据支持。     

仙灵骨葆胶囊对骨质疏松性骨折大鼠骨生长因子及骨折愈合的影响

目的 探讨仙灵骨葆胶囊对骨质疏松性骨折大鼠骨生长因子BMP-2、IGF-1表达及骨折愈合的影响。方法 48只雌性SD大鼠随机分为：假手术组、模型组、雌二醇组、仙灵骨葆组，12只/组，采用“双侧卵巢切除术+右侧股骨干骨折髓内固定术”构建骨质疏松性骨折大鼠模型，评估骨折愈合情况，检测股骨骨痂BMD、股骨骨生物力学指标和血清骨代谢相关指标，检测骨痂BMP-2、IGF-1蛋白表达。结果 模型组较假手术组骨折愈合评分、股骨痂BMD、股骨骨生物力学指标（最大载荷、最大应力、最大位移）、骨痂BMP-2和IGF-I阳性表达均显著降低（P<0.05），雌二醇组、仙灵骨葆组较模型组骨折愈合评分、股骨痂BMD、股骨骨生物力学指标、骨痂BMP-2和IGF-I阳性表达均显著升高（P<0.05），均以仙灵骨葆组最高。模型组较假手术组血清骨代谢指标（BGP、PICP、TRACP-5b）均显著升高（P<0.05），雌二醇组、仙灵骨葆组较模型组血清骨代谢指标均显著降低（P<0.05），以仙灵骨葆组最低。结论 仙灵骨葆胶囊可能通过介导提高骨质疏松性骨折大鼠骨生长因子BMP-2和IGF-1表达，改善骨代谢，加速骨痂形成，增加骨密度，提高骨生物力学，促进骨折愈合。     

Accelerated fracture healing in the geriatric,osteoporotic rat with recombinant human platelet‐derived growth factor‐bb and an injectable beta‐tricalcium phosphate/collagen matrix

Aging and osteoporosis contribute to decreased bone mass and bone mineral density as well as compromised fracture healing rates and bone repair quality. Consequently, the purpose of this study was to determine if recombinant human platelet‐derived growth factor‐BB (rhPDGF‐BB) delivered in an injectable beta‐tricalcium phosphate/collagen matrix would enhance tibial fracture healing in geriatric (>2 years of age), osteoporotic rats. A total of 80 rats were divided equally among four groups: Fracture alone; Fracture plus matrix; Fracture plus matrix and either 0.3 mg/mL or 1.0 mg/mL rhPDGF‐BB. At 3 and 5 weeks, rats were euthanized and treatment outcome was assessed histologically, radiographically, biomechanically, and by micro‐CT. Results indicated rhPDGF‐BB‐treated fractures in osteoporotic, geriatric rats caused a statistically significant time‐dependent increase in torsional strength 5 weeks after treatment. The healed fractures were equivalent in torsional strength to the contralateral, unoperated tibiae. Data from the study are the first, to our knowledge, to underscore rhPDGF‐BB efficacy in an injectable beta‐tricalcium phosphate/collagen matrix accelerated fracture repair in a geriatric, osteoporotic rat model. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J. Orthop Res 26:83–90, 2008     

Effects of calcium supplements on fracture healing in a rat osteoporotic model

Fracture healing is a complex process, which is further complicated if the bone is osteoporotic. Calcium is one of the important minerals in bone and has been found to prevent osteoporosis but its role in fracture healing of osteoporotic bone is still unclear. We carried out a study on the effects of calcium supplementation on the late phase healing of fractured osteoporotic bone using an ovariectomized rat model. Twenty‐four female Sprague–Dawley rats were divided into three groups: sham‐operated (SO), ovariectomized‐control (OVXC), and ovariectomized + calcium supplements (Ca). The right femurs of all the rats were fractured at mid‐epiphysis and a K‐wire was inserted for internal fixation. After 2 months of treatment, the rats were sacrificed and the femora were dissected out for radiological and biomechanical assessment. As expected, osteoporosis resulted in impaired healing as shown by the poor radiological and biomechanical properties of the OVXC group. CT scans showed significantly lower callus volumes in the SO and Ca groups compared to the OVXC group. Radiological scoring of fracture healing and callus staging of the SO and Ca groups were better than the OVXC group. However, the biomechanical parameters of the Ca group were significantly lower than the SO group and similar to the OVXC group. Therefore, calcium supplements may appear to improve fracture healing of osteoporotic bone but failed to improve strength. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1651–1656, 2010