Renal fibrosis, a hallmark of chronic kidney disease progression, arises from complex pathogenic mechanisms involving inflammatory activation, myofibroblast proliferation, and excessive extracellular matrix deposition. Current treatment is limited by poor bioavailability and off-target effects. This review elaborates on how nanotechnology can overcome these obstacles by delivering targeted drugs to fibrotic kidneys. The pathogenesis of renal fibrosis was systematically analyzed, emphasizing the heterogeneity and plasticity of myofibroblast origin and activation. Then the mechanisms of nanoparticle transport in the kidneys, particularly the impact of the fibrotic environment on nanoparticle transport were focused on. The design principles of active and passive targeting of the kidneys by nano-delivery systems in the context of fibrosis are also discussed. Additionally, emerging renal-targeted nanocarriers are summarized, and therapeutic nanomedicines for fibrosis relief are rigorously evaluated. Despite the progress made, challenges remain in the design optimization of nanocarriers, the intelligence of nanomaterials, and the clinical translation of nanomedicines. Future research directions should focus on AI-assisted nanocarrier design, innovation in intelligent nanomaterials, and the application of humanized models. In conclusion, this review highlights the potential of nanomedicine in reshaping the treatment of renal fibrosis and provides practical innovative insights for promoting in-depth and translational research in the future.

Microgravity-induced bone loss has long been a critical issue in space exploration. While countermeasures have been suggested, none have achieved the desired effects. Pinoresinol diglucoside (PDG), an effective constituent of the medicinal herb Eucommia ulmoidis Oliv, was reported to increase peak bone mass in growing rats and mitigate dexamethasone-induced osteoporosis. However, it is unknown if it affects microgravity-induced bone loss. Here, PDG effects were investigated in cultured rat calvarial osteoblasts exposed to simulated microgravity (SMG) and in hindlimb-unloaded mice. PDG (1 × 106 mol/L) prevented SMG-induced osteoblast osteogenesis reduction and oxidative stress (increased levels of oxidative markers and decreased activities of antioxidant enzymes). It alleviated cell proliferation suppression, apoptosis and cell cycle arrest. In hindlimb-suspended mice orally administrated with PDG for 21 days, unloading-induced reduction of femoral bone mineral density, deterioration of bone microstructure and strength, and reduction of osteogenic potential of bone marrow stromal cells were significantly reversed at three dosages tested. It alleviated unloading-induced bone loss (decreased serum bone formation marker but increased resorption marker levels), osteocyte apoptosis (changes in TUNEL staining and apoptosis marker expression), oxidative damages (increased serum 8-isoPGF2α and 8-OHdG levels), inflammation (increased serum inflammatory cytokine levels), and increased bone resorption signal (bone and serum RANKL/OPG expression ratio). These results demonstrated that PDG effectively counteracted hindlimb unloading-induced bone loss by inhibiting osteocyte apoptosis, preventing oxidative stress and inflammation, preserving bone formation and inhibiting resorption. PDG is a good candidate to be further tested for its potential use in preventing spaceflight-induced bone loss and disuse osteoporosis.

This study aims to investigate the therapeutic efficacy of 50 Hz-0.6 mT low-frequency pulsed electromagnetic field (PEMF) on postmenopausal osteoporosis in ovariectomized rats. Thirty 3-month-old female SD rats were selected and divided into a sham operation group (Sham), an ovariectomized model group (OVX), and a low-frequency pulsed electromagnetic field (PEMF) treatment group, with 10 rats in each group. After 8 weeks, the whole-body bone mineral density (BMD) of each group of rats was measured. The treatment group began to receive PEMF stimulation for 90 minutes daily, while the OVX group only received a simulated placement without electricity. After 6 weeks of intervention, all rats were sacrificed and tested for in vitro BMD, micro-CT, biomechanics, serum biochemical indicators, and bone tissue-related proteins. The results showed that the BMD of the OVX group was significantly lower than that of the Sham group 8 weeks after surgery, indicating successful modeling. After 6 weeks of treatment, compared with the OVX group, the PEMF group exhibited significantly increased BMD in the whole body, femur, and vertebral bodies. Micro-CT analysis results showed improved bone microstructure, significantly increased maximum load and bending strength of the femur, elevated levels of serum bone formation markers, and increased expression of osteogenic-related proteins. In conclusion, this study demonstrates that daily 90-minute exposure to 50 Hz-0.6 mT PEMF effectively enhances BMD, improves bone biomechanical properties, optimizes bone microstructure, stimulates bone formation, and inhibits bone resorption in ovariectomized rats, highlighting its therapeutic potential for postmenopausal osteoporosis.

OBJECTIVES:To investigate the effect of sinusoidal alternating electromagnetic field (SEMF) on fracture healing and its mechanism.METHODS:Femoral fracture model was established using SPF male Wistar rats, 30 model rats were randomly divided into model control (MC) and SEMF groups with 15 rats in each group. The SEMF group was given 50 Hz 1.8 mT for 90 min every day, and the MC group was not treated. X-ray examinations were performed every two weeks to determine the formation of bone scabs in each group of rats. Three rats were sacrificed after 2 and 4 weeks of treatment in both groups. Protein was extracted from the fractured femurs, and the expression of type Ⅰ collagen (COL-1), Osterix (OSX), Runt-related transcription factor 2 (RUNX2), and vascular endothelial growth factor (VEGF) protein level was detected by immunoblotting. After 8 weeks, the femur on the operated side was taken for micro-CT scanning to observe fracture healing, angiography to observe blood vessel growth, and organs such as hearts, livers, spleens, lungs, and kidneys were taken for safety evaluation by hematoxylin-eosin staining (HE staining).RESULTS:The bone scab scores of the SEMF group were significantly higher than those of the MC group after 2, 4, 6, and 8 weeks of treatment (all P<0.01); the fracture healing of the SEMF group was better than that of the MC group after 8 weeks, and the bone volume scores of the two groups were 0.243±0.012 and 0.186±0.008, respectively, with statistically significant differences (P<0.01); and the number of blood vessels in the SEMF group was also more than that of the MC group after 8 weeks. The results of protein blotting method showed that the protein expression of VEGF, COL-1, RUNX2, and OSX was higher in the SEMF group than in the MC group after 2 and 4 weeks of treatment (all P<0.05), and the HE staining showed that there was no abnormality in histopathological observation of examined organs in both groups.CONCLUSIONS:SEMF can accelerate fracture healing by promoting the expression of osteogenic factors and vascular proliferation without significant adverse effects.

Objective To determine the effect of isopsoralen (ISO) on the healing of tibia fracture in mice and explore its underlying mechanism. Methods Fifty male C57BL/6 mice (2 month old, 20±2 g) were randomly divided into model group and ISO treatment group, with 25 animals in each group. From the 3rd day after modeling, the mice from the ISO group were given an intragastric gavage of 40 mg/kg ISO, once per day for 28 consecutive days, while those of the model group was given same volume of normal saline in same way. On the 7th, 14th, 21st, and 28th day after gavage, the tibia on the surgical side was taken, and the fracture area was quantified by bone volume/total volume (BV/TV) after micro-CT scanning. The healing and shaping of the fracture end were observed through HE staining. ELISA was used to detect the serum contents of bone alkaline phosphatase (BALP) and procollagen type Ⅰ N-terminal peptide (PINP) on the 14th day of gavage. Western blotting was employed to determine the expression levels of Collagen Ⅰ, Runx2, BMP2, OSX, and VEGF in the tibial callus tissue in 7 and 14 d after gavage. Vascular perfusion was applied to observe the callus microvessels in 28 d to quantitatively analyze the vascular volume fraction and vessel diameter. Immunohistochemical staining was conducted to observe the expression of VEGF in the callus in 14 d after gavage. Results HE staining displayed that the ISO group had faster healing process than the model group. Micro-CT quantification results showed that the ISO group had higher BV/TV ratio in 7 d after gavage though no statistical difference, significantly higher ratio in 14 d (P < 0.05), but obviously lower ratio in 21 and 28 d after gavage (both P < 0.05) when compared with the model group. The serum contents of BALP and PINP were also remarkably higher in the ISO group than the model group (P < 0.05). Western blotting results indicated that the expression levels of Collagen Ⅰ, Runx2, BMP2, OSX and VEGF in the ISO group were higher than those in the model group (P < 0.05). The results of angiography revealed that the vascular volume fraction and vessel diameter were notably increased in the ISO group than the model group (both P < 0.05). Immunohistochemical assay showed that the expression of VEGF was higher in the ISO group than the model group (P < 0.05). Conclusion ISO can improve the activity of osteoblasts, increase the expression of osteogenesis-related proteins, and accelerate the angiogenesis to promote fracture healing.

目的 研究木香烃内酯(CT)对生长期大鼠骨质量的影响.方法 1 月龄雌性 SD 大鼠 30 只,体质量(99±3)g,随机分为 3 组:对照组(Control),9 mg/(kg·d)的 CT处理组(CT-9)和 18 mg/(kg·d)的 CT处理组(CT-18),每组 10 只.适应性饲养 3 d后,灌胃给药,Control组每天灌服等体积蒸馏水,每周称一次体质量,每 4 周检测一次全身骨密度(BMD).8 周后安乐死所有大鼠,检测股骨和椎骨离体 BMD、进行 micro CT 扫描和骨生物力学实验.结果 各组大鼠实验过程中体质量未出现统计学意义,8 周时 CT-9 组和 CT-18 组的全身 BMD 及离体股骨、椎骨BMD均显著高于 Control组,CT-18 组的股骨弹性模量和最大载荷显著高于 Control组,CT-9 组和 CT-18 组的相对骨体积、骨小梁数和体积骨密度均显著高于 Control组,骨小梁分离度显著低于 Control 组.结论 CT 能提高生长期大鼠的骨质量,具有开发预防和治疗骨质疏松药物的潜力.

Objective To investigate the effects of ethinylestradiol on bone quality in postmenopausal osteoporosis mice. Methods Thirty SPF C57 female mice were randomly divided into 3 groups with 10 mice in each group: sham operation group, model group,and ethinylestradiol group. Ethinylestradiol group was given 100 μg/kg ethinylestradiol intragastrically every day, sham operation group and model group were given equal volume of distilled water intragastrically. Samples were taken 12 weeks after administration,and organ coefficients, major organs and bone histopathological sections were observed, respectively, and Micro CT, biomechanical and serum biochemical indexes were analyzed. Results Compared with model group, the body weight of ethinylestradiol group was significantly decreased（P ＜ 0.05, 0.01）. The organ coefficients of ethinylestradiol group mice showed no significant differences except uterus, model group, and sham operation group, and no obvious lesions were found in the main organs. Compared with the model group, the bone trabecular structure in the ethinylestradiol group was dense and there were fewer fat cells. Compared with the model group, the maximum biomechanical load and elastic modulus of ethinylestradiol group were significantly increased（P ＜ 0.05, 0.01）.Compared with model group, the Tb.BMD, Tb.N, Tb.Th, and Tb.BV/TV levels of ethinylestradiol group were significantly increased,while the Tb.Sp value was significantly decreased（P ＜ 0.01）. Compared with model group, the mean serum OCN and PINP levels in ethinylestradiol group were significantly increased, TRACP-5b and CTX-I levels were significantly decreased（P ＜ 0.01）. Conclusion Ethinylestradiol can improve the bone quality of postmenopausal osteoporosis mice without damaging the major organs.

目的 研究仙灵骨葆胶囊对生长期大鼠骨强度的影响.方法 将 20 只 1 月龄 SPF级 SD雌性大鼠按随机数字表法分为对照组和仙灵骨葆组,每组 10 只.仙灵骨葆组每天灌服 378 mg/kg仙灵骨葆胶囊,对照组每天给予等体积蒸馏水.实验期间每两周测一次全身骨密度,待第 6 周仙灵骨葆组显著高于对照组后安乐死取材.取脏器、股骨、胫骨和椎骨进行病理学分析、骨密度检测、生物力学检测、micro CT 分析以及血清生化指标检测.结果 实验期间各组大鼠体质量呈上升趋势,两组间比较并无统计学意义,脏器无明显病理学改变;给药 6 周后仙灵骨葆组全身骨密度、股骨骨密度和椎骨骨密度都显著高于对照组(P<0.05);仙灵骨葆组股骨最大载荷和屈服强度显著高于对照组(P<0.05),椎骨最大载荷也显著高于对照组(P<0.05);仙灵骨葆组胫骨骨体积分数、骨小梁厚度和骨小梁数显著高于对照组(P<0.05),骨小梁分离度显著低于对照组(P<0.05);与对照组相比,仙灵骨葆组血清 OCN 含量上升、TRACP-5b含量下降,差异具有统计学意义(P<0.05).结论 仙灵骨葆胶囊可能通过抑制骨吸收与促进骨形成来提高生长期大鼠骨强度,具有通过提高生长期大鼠峰值骨量来预防后期骨质疏松的潜力.

近年来,随着国内外航空航天事业的蓬勃发展,人类对太空的探索逐步加深.然而,在太空飞行期间,宇航员暴露于微重力环境下,每月有 1%～2%的骨质流失.骨质的流失会增加骨质疏松和骨折的风险,威胁着宇航员的身体健康和长期太空任务的可行性.因此,研究者通过太空实验和地面模拟微重力实验探索发病机制并寻求有效的预防和治疗措施.本文将对微重力诱导的骨量丢失机制、对抗措施以及地面常用模拟实验技术加以概述.

OBJECTIVE:To explore effects of isopsoralen (ISO) with different doses on fracture and vascular healing in mice.METHODS:Sixty 2-month-old male C57BL/6 mices with body mass of (20±2) g were selected and divided into 4 groups by random number table method:model group (model), low dose group (isopsoralen-low dose, ISO-L), medium dose group (isopsoralen-medium dose, ISO-M) and high dose group (isopsoralen-high dose, ISO-H), with 15 animals in each group. The right tibial fracture model was established. After operation, ISO-L group, ISO-M group and ISO-H group were given ISO concentration of 10 mg·kg-1, 20 mg·kg-1 and 40 mg·kg-1, respectively. Model group was given same volume of normal saline once a day for 28 days. Weighed once a week. X-ray was performed on 7, 14, 21 and 28 days, respectively, and modified I.R. Garrett scoring method was used to evaluate callus growth. After 28 days, the main organs were stripped and weighed, and organ coefficients were calculated. Hematoxylin eosin staining (HE staining) was performed on the organs to observe whether there were pathological structural changes. Micro-computed tomography (Micro-CT) was used to scan fracture area and conduct three-dimensional reconstruction to obtain the effect map, and quantify bone volume fraction (bone volume/total volume, BV/TV). After decalcification, the tibia was embedded in paraffin wax and sectioned. The healing and shape of fracture end were observed by HE staining and ferruxin solid green staining. The right tibia was removed and decalcified after intravascular infusion of Microfil contrast agent. Micro-CT was used to scan the callus microvessels in the fracture area, and the vascular volume fraction and vessel diameter were quantified.RESULTS:After 28 days of administration, there was no significant difference in body mass and organ coefficient among all groups (P>0.05), and no significant pathological changes were found in HE staining of organs. The results of X-ray and improved I.R. Garrett score showed that ISO-M group was higher than that of Model group at 28 days (P<0.05). Scores of ISO-H group at 14, 21 and 28 days were higher than those of the other 3 groups (P<0.05). Micro-CT results showed intracavitary callus in ISO-M group was significantly reduced, which was lower than that in Model group (P<0.05), most of the callus in ISO-H group were subsided, and BV/TV in ISO-H group was lower than that in the other 3 groups (P<0.05). The results of HE staining and ferrubens solid green staining showed fracture area of ISO-H group was closed, continuous laminar bone had appeared, and the fracture healing process was higher than that of other groups. Angiographic results showed vascular volume fraction in ISO-H and ISO-M groups was higher than that in Model and ISO-L groups (P<0.05), and the vascular diameter in ISO-H and ISO-M groups was higher than that in Model and ISO-L groups (P<0.05).CONCLUSION:In the concentration range of 10-40 mg·kg-1, ISO has no obvious toxic and side effects, and could improve bone microstructure, promote formation of callus microvessels, and accelerate healing of fracture ends in a concentration-dependent manner.

目的 本研究旨在通过综合比较本课题组既往研究中建立大鼠骨折模型的不同方法之间的差异性及模型的稳定性,并评价改良后大鼠截骨模型建立方法的科学性及可靠性,为骨折研究提供可靠的动物模型建立方法.方法 根据不同造模方式将大鼠分为闭合性骨折模型组以及开放性骨折模型组,闭合性骨折模型组通过自制闭合性骨折造模仪建立股骨中段骨折,砝码 500 g,下落高度分别为 22、26、30 cm.开放性骨折模型组通过手术制造大鼠股骨中段横形或短斜形骨折,其中单纯克氏针固定组采用不同型号克氏针进行髓内固定,克氏针加线固定组在克氏针进行髓内固定的基础上,使用可吸收线将两骨折断端进行牵拉固定.结果 闭合性骨折模型组中砝码下落高度为 22、26、30 cm,造模成功率依次为 33%、50%、17%.开放性骨折模型组中使用 1.2 mm 克氏针内固定其骨折断端的稳定性明显优于 0.8 和 1.0 mm克氏针内固定.克氏针加线固定组相比于单纯克氏针固定组骨折断端更稳定.HE染色结果显示克氏针加线固定组其固定稳定,骨折愈合良好且未见可吸收线对其产生不良影响.结论 开放性骨折模型较闭合性骨折模型更容易控制骨折类型,保证实验对象的同质性.克氏针加线固定组较单纯克氏针固定组固定效果更稳定,可以避免因骨折断端固定不牢造成骨折不愈合甚至延迟愈合,进而导致样本脱落以及因固定不牢造成的实验结果偏差,确保了实验对象的同质性并降低了随机误差.

骨质疏松症是目前老龄化社会急需解决的慢性骨科疾病,是一种以骨量丧失、骨微结构恶化为特征的全身性骨骼疾病,因此如何有效地预防和治疗骨质疏松症越来越受到人们的关注.槲皮素是自然界广泛存在天然黄酮醇类化合物,具有雌激素样作用,可抑制骨吸收和促进骨形成.槲皮素通过抑制破骨细胞、调控骨髓间充质干细胞的细胞机制,促进骨形成、抑制骨吸收的信号通路机制,以及雌激素信号途径改善骨质疏松.综述了槲皮素改善骨质疏松的作用机制,希望为槲皮素的临床应用提供参考.

Oxidative stress has been considered to be closely related to spaceflight‐induced bone loss; however, mechanism is elusive and there are no effective countermeasures. Using cultured rat calvarial osteoblasts exposed to microgravity simulated by a random positioning machine, this study addressed the hypotheses that microgravity‐induced shortening of primary cilia leads to oxidative stress and that primary cilium protection prevents oxidative stress and osteogenesis loss. Microgravity was found to induce oxidative stress (as represented by increased levels of reactive oxygen species (ROS) and malondialdehyde production, and decreased activities of antioxidant enzymes), which was perfectly replicated in osteoblasts growing in NG with abrogated primary cilia (created by transfection of an interfering RNA), suggesting the possibility that shortening of primary cilia leads to oxidative stress. Oxidative stress was accompanied by mitochondrial dysfunction (represented by increased mitochondrial ROS and decreased mitochondrial membrane potential) and intracellular Ca 2+ overload, and the latter was found to be caused by increased activity of Ca 2+ channel transient receptor potential vanilloid 4 (TRPV4), as also evidenced by TRPV4 agonist GSK1016790A‐elicited Ca 2+ influx. Supplementation of HC‐067047, a specific antagonist of TRPV4, attenuated microgravity‐induced mitochondrial dysfunction, oxidative stress, and osteogenesis loss. Although TRPV4 was found localized in primary cilia and expressed at low levels in NG, microgravity‐induced shortening of primary cilia led to increased TRPV4 levels and Ca 2+ influx. When primary cilia were protected by miR‐129‐3p overexpression or supplementation with a natural flavonoid moslosooflavone, microgravity‐induced increased TRPV4 expression, mitochondrial dysfunction, oxidative stress, and osteogenesis loss were all prevented. Our data revealed a new mechanism that primary cilia function as a controller for TRPV4 expression. Microgravity‐induced injury on primary cilia leads to increased expression and overactive channel of TRPV4, causing intracellular Ca 2+ overload and oxidative stress, and primary cilium protection could be an effective countermeasure against microgravity‐induced oxidative stress and loss of osteogenic potential of osteoblasts.

目的 研究蛇床子素(osthol)是否通过激活丝氨酸/苏氨酸蛋白激酶(AKT)/内皮型一氧化氮合酶(endothelial nitric oxide synthase,eNOS)/可溶性鸟苷酸环化酶(soluble guanylate cyclase,sGC)/蛋白激酶G(protein kinase G,PKG)信号通路促进大鼠颅骨成骨细胞(rat calvarial osteoblasts,ROBs)矿化成熟.方法 检测蛇床子素处理ROBs后,成骨性转录因子RUNX2、OSX以及AKT/eNOS/sGC/PKG信号途径蛋白表达水平、免疫荧光法观察信号通路下游蛋白核易位;检测碱性磷酸酶(alkline phosphatase,ALP)活性;用AKT特异性抑制剂MK-2206 阻断AKT功能后,检测MK-2206 对 AKT/eNOS/sGC/PKG信号途径活性及对ROBs矿化成熟的影响,进一步评估蛇床子素促进成骨细胞矿化成熟的潜在机制.结果 蛇床子素处理ROBs后,成骨性转录因子RUNX2、OSX蛋白及AKT/eNOS/sGC/PKG信号通路蛋白表达量均增加,ALP活性上升;加入AKT抑制剂后,蛇床子素不再激活AKT/eNOS/sGC/PKG信号通路,阻断了蛇床子素促进ROBs的矿化成熟.结论 蛇床子素可通过激活AKT/eNOS/sGC/PKG信号通路促进成骨细胞矿化成熟.

目的 探讨淫羊藿苷对模拟微重力环境大鼠骨丢失的防治作用.方法 取2 月龄Wistar雄性大鼠30 只,采用随机数字表法分为对照组、尾吊组、淫羊藿苷组,每组 10 只.尾吊组、淫羊藿苷组均建立尾吊模型,淫羊藿苷组给予淫羊藿苷 50 mg/kg灌胃,对照组和尾吊组则给予等体积蒸馏水,每周称体质量1 次.给药 28d后麻醉下腹主动脉采血处死大鼠,检测股骨骨密度并进行生物力学检测,观察并分析胫骨的HE染色结果,进行胫骨Mirco-CT检测,测定血清骨代谢生化指标.结果 尾吊组和淫羊藿苷组大鼠体质量下降,但差异无统计学意义;淫羊藿苷组骨密度、骨生物力学参数较尾吊组均有所改善;淫羊藿苷组骨小梁形态、数量与厚度较尾吊组均有显著改善;淫羊藿苷组骨钙素(osteocalcin,OCN)水平较尾吊组明显增加,抗酒石酸酸性磷酸酶 5b(tartrate-resistant acid phosphatase-5b,TRACP-5b)水平较尾吊组明显降低.结论 淫羊藿苷对模拟微重力环境大鼠骨丢失具有良好的防治作用.

中老年人骨质疏松症( OP)不仅极大降低患者的生活质量,还严重威胁其生命安全,给社会带来了巨大的负担[1].因此寻找安全可靠的治疗方法尤为重要.中草药因不良反应小得到了国内外学者的重视及广大患者的肯定[2].杜仲被认为是防治OP的经典用药,《本草纲目》记载其具有"治腰膝痛,补中益精气,坚筋骨,强志"的功效[3].

Objective:To study the effects of a simulated plateau environment on fracture healing in rats.Methods:A rat model of mid-femoral fracture was established by hacksaw truncation and intramedullary fixation with Kirschner wires in 60 male Wistar rats which were divide into 2 groups ( n=30) by the random number table method. The rats in the control group were raised in the animal experiment center of The 940 Hospital of Joint Logistic Support Force of Chinese PLA at an altitude of 1,400 m, while the rats in the plateau group were placed in an animal experimental cabin in a simulated plateau environment at a simulated altitude of 5,000 m. The body weight was weighed once a week and X-ray films were taken every 2 weeks. Blood samples were collected after 4 weeks for detection of biochemical indicators of bone metabolism. After 8 weeks, the femurs of the surgical side were taken for bone biomechanical detection and the bone mineral density of the healthy side was detected. After 4 and 8 weeks, the femurs of the surgical side were taken for in vitro Micro-CT scanning and angiography detection. After 1, 2, 4 and 8 weeks, the femurs of the surgical side were taken for bone histopathologic detection. Results:During the entire experiment, no rats in the control group died while the mortality rate of the rats in the plateau group was as high as 26.7% (8/30). In the plateau group, some organs were pathologically damaged in the rats, fracture union was delayed, and the callus differentiated and matured slowly with the chondrocytes still dominant at the 8th week. The bone mineral density and the maximum load of the femur in the plateau group were significantly lower than those in the control group ( P< 0.05). Angiography showed that the rats in the plateau group had microvascular proliferation which did not penetrate the fracture end at the 8th week. The bone formation indexes like osteocalcin, procollagen type Ⅰ N-terminal propeptide (PⅠNP), and osteoprotegerin of the rats in the plateau group were significantly lower than those in the control group at the 4th week ( P<0.05). The bone resorption indexes like tartrate resistant acid phosphatase 5b (TRACP-5b) and receptor activator for nuclear factor-κB ligand (RANKL) in the plateau group were significantly higher than those in the control group ( P<0.05). Conclusion:A simulated plateau environment at an altitude of 5,000 m may lead to delayed fracture healing in rats.

Objective To determine the effect of pinoresinol diglucoside (PDG) on bone quality in growing rats and evaluate its potential as an anti-osteoporosis drug. Methods A total of 30 1-month-old female SD rats (body weight 107±7 g) were randomly divided into 3 groups: control group (Control), 25 mg/(kg·d) PDG treatment group (PDG-25) and 50 mg/(kg·d) PDG treatment group (PDG-50), with 10 rats in each group. The rats in the PDG-25 group and PDG-50 group were given corresponding doses of PDG intragastrically every day, and those of the control group was given equal volume distilled water. Their body mineral density (BMD) of the whole body was measured in 2, 4 and 6 weeks after treatment. In the end of 6 weeks, all rats were sacrificed, and organ coefficients of important organs were calculated. Micro-CT scanning, bone biomechanical test and serum biochemical tests of bone metabolism were performed. Results There were no significant differences in body weight and main organ coefficients among the groups. At 6 weeks, the BMD value was significantly higher in the PDG-25 group and PDG-50 group than the Control group (P < 0.05). The PDG-50 group had significantly higher relative bone volume, trabecular number and volumetric bone mineral density (P < 0.05), lower trabecular separation (P < 0.05) than the Control group, and the bone microstructure of PDG-25 group and PDG-50 group was significantly better than that of Control group. The PDG-50 group had elevated elastic modulus of femur (P < 0.05), larger maximum load of vertebrae (P < 0.05). The PDG-50 group had increased content of serum osteocalcin (P < 0.01), but obviously lower content of serum tartrate resistant acid phosphatase 5b (P < 0.01), when compared with the Control group. The content of serum osteocalcin in the PDG-25 group was significantly higher than that in the Control group (P < 0.05). Conclusion PDG can effectively improve bone mineral density, optimize bone microstructure, enhance bone strength, promote bone formation, inhibit bone resorption and improve bone quality.

Objective To study the potentials of pulsed electromagnetic fields（PEMFs）in different intensities on proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells（BMSCs）. Methods Whole bone marrow adherence method was used to obtain bone marrow mesenchymal stem cells from about 100g Wistar rat bone which were cultured in DMEM containing 10% FBS.BMSCs were fused to 80-90% and cultured by subculture. They were randomly divided into seven groups, Six groups were exposed to PEMFs（50 Hz frequency）or 90 min/day under the following intensities:0.6, 1.2, 1.8, 2.4, 3.0, and 3.6 mT respectively（with a 0.6 mT increment interval）. One group was used as control cultured in same condition without PEMF treatment（0.0 mT）. The cell morphology was observed, and the proliferation was measured with tetramethylazolium blue. The Alkaline phosphatase（ALP）activity was measured at 6, 9,and 12 days, respectively. On the 10th and 15th days of magnetic field treatment, ALP staining and calcium nodule staining were performed, and the clone number and area were calculated. Results MTT results showed that treatment for 3 days induced a signi?cantlyincreasedBMSCs proliferation at 0.6 mT, 1.8 mT, 2.4 mT and 3.6 mT（P ＜ 0.01）. Compared to all the other experimental groups treatments at 2.4 mT significantly increased BMSCs proliferation. ALP activity results showed that treatment for 6 days significantly increasedALP activity at PEMF groups. Treatment for 9 days induced a significantlyincreasedALP activity at 0.6 mT, 2.4 mT and 3.6 mT.Treatments at 50 Hz and 2.4 mT significantly increased activity of ALP than the other experimental groups（P ＜ 0.01）Consistently, ALP histochemical analysis of BMSCs treated with PEMFs for 9 days reveals that PEMFs exposure increased ALP activity in an intensity-dependent manner. Compared to all the other experimental groups, treatments at 2.4 mT significantly increased the number and area of ALP histochemical analysis, as well as Alizarin red-stained（P ＜ 0.01）. Conclusion Exposure at 50 Hz and 2.4 mT PEMFs significantly enhanced BMSCsproliferation and osteogenic differentiation, which is a theoretical basis that can pulse electromagnetic fields in the treatment of osteoporosis.

OBJECTIVETo explore whether the effect of low-frequency pulsed electromagnetic fields (PEMFs) in promoting osteoblast mineralization and maturation is related to the primary cilia, polycystin2 (PC2) and sAC/PKA/CREB signaling pathway.METHODSWe detected the expression levels of PC2, sAC, PKA, CREB and their phosphorylated proteins in primary rat calvarial osteoblasts exposed to 50 Hz 0.6 mT PEMFs for 0, 5, 15, 30, 60, 90, and 120 min. We blocked PC2 function with amiloride hydrochloride and detected the changes in the activity of sAC/PKA/CREB signal pathway and the mineralization and maturation of the osteoblasts. These examinations were repeated in the osteoblasts after specific knockdown of PC2 via RNA interference and were the co-localization of PC2, sAC, PKA, CREB and their phosphorylated proteins with the primary cilia were using immunofluorescence staining. The expressions of PC2 and the signaling proteins of sAC/PKA/CREB pathway were detected after inhibition of primary ciliation by RNA interference.RESULTSThe expression levels of PC2, sAC, p-PKA and p- CREB were significantly increased in the osteoblasts after exposure to PEMFs for different time lengths (P < 0.01). Blocking PC2 function or PC2 knockdown in the osteoblasts resulted in failure of sAC/PKA/CREB signaling pathway activation and arrest of osteoblast mineralization and maturation. PC2, sAC, p-PKA and p-CREB were localized to the entire primary cilia or its roots, but PKA and CREB were not detected in the primary cilia. After interference of the primary cilia, PEMFs exposure no longer caused increase of PC2 expression and failed to activate the sAC/PKA/CREB signaling pathway or promote osteoblast mineralization and maturation.CONCLUSIONPC2, located on the surface of the primary cilia of osteoblasts, can perceive and transmit the physical signals from PEMFs and promote the mineralization and maturation of osteoblasts by activating the PC2/ sAC/PKA/CREB signaling pathway.