大鼠脊柱融合模型中BBP增强BMP-2的骨诱导作用

[目的]验证在大鼠脊柱融合模型中BBP对于rhBMP-2骨诱导作用的影响。[方法]采取Lewis大鼠的脊柱后外侧横突间融合模型,在胶原海绵为载体的rhBMP-2中加入BBP并减少rhBMP-2的用量,测试两种不同剂量的BBP(500 ug和1 000 ug)有或无低剂量的rhBMP2(1 ug)时的骨融合效果,并与单纯的低剂量rhBMP-2(1 ug)组相对比。融合效果采用手工评估,影像学评分,Micro-CT评估和组织学评估4种方法。[结果]BBP本身不管是低剂量还是高剂量均不能诱导骨融合。BBP复合低剂量BMP-2不能完全取得与高剂量BMP-2完全相同的效果,但可以减少BMP-2的用量。加入BBP的低剂量BMP-2组显然较低剂量BMP-2组融合率高,而且与高剂量BMP-2组的融合率相近,而且BBP的低剂量BMP-2组显然较低剂量BMP-2组融合的要早。[结论]在大鼠的脊柱融合模型中,BBP本身不管是低剂量还是高剂量均不能诱导骨融合。BBP可以增强BMP-2的骨形成作用,提高融合率,降低BMP-2的使用剂量以及减少了剂量相关性副作用的发生率,但不能取得与高剂量BMP-2完全相同的效果。BBP可以减少脊柱融合所需的时间和提高形成骨的质量。进一步的研究可以优化BBP和BMP-2的剂量,从而为以后的临床手术应用中取得更好的融合效果。     

The study of abnormal bone development in the Apert syndrome Fgfr2+/S252W mouse using a 3D hydrogel culture model

Apert syndrome is caused by mutations in fibroblast growth factor receptor 2 (Fgfr2) and is characterized by craniosynostosis and other skeletal abnormalities. The Apert syndrome Fgfr2+/S252W mouse model exhibits perinatal lethality. A 3D hydrogel culture model, derived from tissue engineering strategies, was used to extend the study of the effect of the Fgfr2+/S252W mutation in differentiating osteoblasts postnatally. We isolated cells from the long bones of Apert Fgfr2+/S252W mice (n=6) and cells from the wild-type sibling mice (n=6) to be used as controls. During monolayer expansion, Fgfr2+/S252W cells demonstrated increased proliferation and ALP activity, as well as altered responses of these cellular functions in the presence of FGF ligands with different binding specificity (FGF2 or FGF10). To better mimic the in vivo disease development scenario, cells were also encapsulated in 3D hydrogels and their phenotype in 3D in vitro culture was compared to that of in vivo tissue specimens. After 4 weeks in 3D culture in osteogenic medium, Fgfr2+/S252W cells expressed 2.8-fold more collagen type I and 3.3-fold more osteocalcin than did wild-type controls (p<0.01). Meanwhile, Fgfr2+/S252W cells showed decreased bone matrix remodeling and expressed 87% less Metalloprotease-13 and 71% less Noggin (p<0.01). The S252W mutation also led to significantly higher production of collagen type I and II in 3D as shown by immunofluorescence staining. In situ hybridization and alizarin red S staining of postnatal day 0 (P0) mouse limb sections demonstrated significantly higher levels of osteopontin expression and mineralization in Fgfr2+/S252W mice. Complementary to in vivo findings, this 3D hydrogel culture system provides an effective in vitro venue to study the pathogenesis of Apert syndrome caused by the analogous mutation in humans.     

Effect of bone morphogenetic protein 2 on tendon‐to‐bone healing in a canine flexor tendon model

Tendon‐to‐bone healing is typically poor, with a high rate of repair‐site rupture. Bone loss after tendon‐to‐bone repair may contribute to poor outcomes. Therefore, we hypothesized that the local application of the osteogenic growth factor bone morphogenetic protein 2 (BMP‐2) would promote bone formation, leading to improved repair‐site mechanical properties. Intrasynovial canine flexor tendons were injured in Zone 1 and repaired into bone tunnels in the distal phalanx. BMP‐2 was delivered to the repair site using either a calcium phosphate matrix (CPM) or a collagen sponge (COL) carrier. Each animal also received carrier alone in an adjacent repair to serve as an internal control. Repairs were evaluated at 21 days using biomechanical, radiographic, and histologic assays. Although an increase in osteoid formation was noted histologically, no significant increases in bone mineral density occurred. When excluding functional failures (i.e., ruptured and gapped repairs), mechanical properties were not different when comparing BMP‐2/CPM groups with carrier controls. A significantly higher percentage of BMP‐2 treated specimens had a maximum force <20 N compared to carrier controls. While tendon‐to‐bone healing can be enhanced by addressing the bone loss that typically occurs after surgical repair, the delivery of BMP‐2 using the concentrations and methods of the current study did not improve mechanical properties over carrier alone. The anticipated anabolic effect of BMP‐2 was insufficient in the short time frame of this study to counter the post‐repair loss of bone. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1702–1709, 2012     

Slow release of bone morphogenetic protein 2 from a gelatin sponge to promote regeneration of tracheal cartilage in a canine model

OBJECTIVES: We investigated whether bone morphogenetic protein 2, released slowly from a gelatin sponge, could induce cartilage regeneration in a canine model of tracheomalacia and evaluated the long-term results. METHODS: A 1 x 5-cm gap was made in the anterior cervical trachea by removing 5-cm long strips of 10 sequential cartilagines. In the control group (n = 5), the gaps were left untreated. In the gelatin sponge group (n = 5), a gelatin sponge soaked in a buffer solution was implanted in each defect. In the bone morphogenetic protein group (n = 5), a gelatin sponge soaked in a buffer solution containing 12 microg bone morphogenetic protein 2 was implanted in each defect. RESULTS: Tracheomalacia was observed in the control and gelatin sponge groups but not in the bone morphogenetic protein group. No regenerated cartilage was detected in the control or gelatin sponge groups, even 6 months after surgery. In contrast, regenerated cartilage, which had developed from the host perichondrium, was observed around the stumps of the resected cartilagines in the bone morphogenetic protein group. This regenerated cartilage maintained the integrity of the internal lumen for longer than 6 months. A compressive fracture test revealed that the tracheal cartilage in the bone morphogenetic protein group was significantly more stable than that in the gelatin sponge and control groups (P =.0015 and P =.0001, respectively). CONCLUSIONS: In this canine model of tracheomalacia, cartilage regeneration was induced around the stumps of tracheal cartilagines by bone morphogenetic protein 2 released slowly from a gelatin sponge. This regenerated cartilage was not reabsorbed for longer than 6 months and was strong enough to maintain the integrity of the internal lumen of the trachea.     

Evaluation of osteogenic cell differentiation in response to bone morphogenetic protein or demineralized bone matrix in a critical sized defect model using GFP reporter mice

We evaluated the osteoprogenitor response to rhBMP‐2 and DBM in a transgenic mouse critical sized defect. The mice expressed Col3.6GFPtopaz (a pre‐osteoblastic marker), Col2.3GFPemerald (an osteoblastic marker) and α‐smooth muscle actin (α‐SMA‐Cherry, a pericyte/myofibroblast marker). We assessed defect healing at various time points using radiographs, frozen, and conventional histologic analyses. GFP signal in regions of interest corresponding to the areas of new bone formation was quantified using a novel computer assisted algorithm. All defects treated with rhBMP‐2 healed. In contrast, the majority of the defects in the DBM (27/30) and control (28/30) groups did not heal. Quantitation of pre‐osteoblasts demonstrated a maximal response (% GFP+ cells/TV) in the Col3.6GFPtopaz mice at day 7 (7.2% ± 6.0, p < 0.05 compared to days 14, 21, 28, and 56). The maximal response of the Col2.3GFP cells was seen at days 14 (8.04% ± 5.0) and 21 (8.31% ± 4.32), p < 0.05. In contrast, DBM and control groups showed a limited osteogenic response at all time points. In conclusion, we demonstrated that the BMP and DBM induce vastly different osteogenic responses which should influence their clinical application as bone graft substitutes. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1120–1128, 2014.     

Improved union and bone strength in a mouse model of NF1 pseudarthrosis treated with recombinant human bone morphogenetic protein‐2 and zoledronic acid

Tibial pseudarthrosis associated with Neurofibromatosis type 1 (NF1) is an orthopedic condition with consistently poor clinical outcomes. Using a murine model that features localized double inactivation of the Nf1 gene in an experimental tibial fracture, we tested the effects of recombinant human bone morphogenetic protein‐2 (rhBMP‐2) and/or the bisphosphonate zoledronic acid (ZA). Tibiae were harvested at 3 weeks for analysis, at which time there was negligible healing in un‐treated control fractures (7% union). In contrast, rhBMP‐2 and rhBMP‐2/ZA groups showed significantly greater union (87% and 93%, p < 0.01 for both). Treatment with rhBMP‐2 led to a 12‐fold increase in callus bone volume and this was further increased in the rhBMP‐2/ZA group. Mechanical testing of the healed rhBMP‐2 and rhBMP‐2/ZA fractures showed that the latter group had significantly higher mechanical strength and was restored to that of the un‐fractured contralateral leg. Co‐treatment with rhBMP‐2/ZA also reduced fibrous tissue infiltration at the fracture site compared to rhBMP alone (p = 0.068). These data support the future clinical investigation of this combination of anabolic and anti‐resorptive agents for the treatment of NF1 pseudarthrosis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:930–936, 2018.

     

Disproportionally low clearance of macromolecules from the plasma to the peritoneal cavity in a mouse model of peritoneal dialysis.

BACKGROUND: This study was performed to establish a model for quantitative measurements of a number of basic peritoneal transport parameters, particularly transperitoneal clearances (Cl) of macromolecules, during mouse peritoneal dialysis. METHODS: Mice were anaesthetized using 3% isofluorane inhalation anaesthesia. The right jugular vein and the left femoral artery were cannulated for infusion and sampling purposes and for registration of (mean) arterial blood pressure. Access to the peritoneal cavity occurred via a thin abdominal catheter (? 0.7 mm). About 2.5 ml of either 4% (n = 9) or 1.5% (n = 5) glucose containing PD-fluid were instilled intraperitoneally (i.p.). Dialysate volume was followed vs time using i.p. RISA ((125)I human serum albumin) as a volume marker, after correcting for RISA mass disappearance from the peritoneum, assessed separately (n = 11). Microsampling (10 microl) of plasma and dialysate was performed for determinations of glucose, haematocrit, radioactivity (RISA and (51)Cr-EDTA) and Ficoll. RESULTS: The i.p. volume vs time curves [V(D)(t)] were, after scaling, similar to those observed in humans (and in rats). Clearance of RISA out of the peritoneal cavity (Cl(out)) was 9.33 +/- 0.83 microl/min and the clearance of RISA to plasma (Cl-->P) and the RISA clearance to the peritoneal cavity (Cl-->D) were 1.49 +/- 0.13 and 0.084 +/- 0.008 microl/min, respectively. The peritoneal transport coefficients for (51)Cr-EDTA and glucose, as well as Cl(out) and Cl-->P, were 13-17% of those previously assessed in 300 g rats, whereas Cl-->D was only approximately 2% of that in rat. CONCLUSIONS: All peritoneal transport parameters measured, except Cl-->D, scaled very well to the corresponding human data. The mechanisms of the disproportionally low clearance of macromolecules from the plasma to the peritoneal cavity in mice remain elusive and warrant further study.     

Enhanced Wnt signaling improves bone mass and strength,but not brittleness,in the Col1a1+/mov13 mouse model of type I Osteogenesis Imperfecta

Osteogenesis Imperfecta (OI) comprises a group of genetic skeletal fragility disorders. The mildest form of OI, Osteogenesis Imperfecta type I, is frequently caused by haploinsufficiency mutations in COL1A1, the gene encoding the α₁(I) chain of type 1 collagen. Children with OI type I have a 95-fold higher fracture rate compared to unaffected children. Therapies for OI type I in the pediatric population are limited to anti-catabolic agents. In adults with osteoporosis, anabolic therapies that enhance Wnt signaling in bone improve bone mass, and ongoing clinical trials are determining if these therapies also reduce fracture risk. We performed a proof-of-principle experiment in mice to determine whether enhancing Wnt signaling in bone could benefit children with OI type I. We crossed a mouse model of OI type I (Col1a1^+/Mov13) with a high bone mass (HBM) mouse (Lrp5^+/p.A214V) that has increased bone strength from enhanced Wnt signaling. Offspring that inherited the OI and HBM alleles had higher bone mass and strength than mice that inherited the OI allele alone. However, OI + HBM and OI mice still had bones with lower ductility compared to wild-type mice. We conclude that enhancing Wnt signaling does not make OI bone normal, but does improve bone properties that could reduce fracture risk. Therefore, agents that enhance Wnt signaling are likely to benefit children and adults with OI type 1.     

鞘内注射驱动蛋白17竞争性小肽抑制剂对骨癌痛小鼠的镇痛效果

目的 评价鞘内注射驱动蛋白17竞争性小肽抑制剂RC-13对骨癌痛小鼠的镇痛效果.方法 雄性C3H/HeJ小鼠40只,6～8周龄,体重20 ～ 25 g,采用随机数字表法,将其随机分为5组(n=8):假手术组(S组)、骨癌痛+5μ1 DMSO组(R0组)、骨癌痛+2.5 μg RC-13组(R1组)、骨癌痛+5μg RC-13组(R2组)和骨癌痛+10 μg RC-13组(R3组).R0组、R1组、R2组和R3组小鼠右侧股骨骨髓腔内注射含约2× 105个纤维肉瘤细胞的20μl α-MEM以制备骨癌痛模型.骨癌痛各组于接种肿瘤细胞后第14天开始,每天定时分别鞘内注射10％ DMSO 5 μl和溶于10％ DMSO的RC-13 2.5 μg/5 μl、5 μg/5μl、10 μg/5 μl,连续3d,每天1次.各组于接种前1d、接种后3、5、7、10、14 d时测定小鼠机械缩足阈值和自发抬足次数,R0-3组在给药结束后1、3、5和7d时行相同行为学测定.结果 与S组比较,其余组接种后7～14d时小鼠机械缩足阈值降低,自发抬足次数增加(P＜0.05);与R0组比较,R1组给药结束后1d、R2组1和3d、R3 组1、3、5d时机械缩足阈值升高,自发抬足次数减少(P＜0.05);与R1组比较,R2组给药结束后3d、R3 组1、3、5d时机械缩足阈值升高,自发抬足次数减少(P＜0.05);与R2组比较,R3组给药结束后1和3d时机械缩足阈值升高,自发抬足次数减少(P＜0.05).结论 鞘内注射驱动蛋白17竞争性小肽抑制剂RC-13对骨癌痛小鼠具有良好的镇痛效果,其效应呈剂量依赖性.     

鞘内注射艾芬地尔对骨癌痛小鼠脊髓NR2B mRNA表达的影响

目的 探讨鞘内注射艾芬地尔对骨癌痛小鼠脊髓N-甲基-D-天冬氨酸(NMDA)受体2B亚基(NR2B)mRNA表达的影响.方法 雄性C3H/HeJ小鼠140只,体重20～25 g,4～6周龄,随机分为5组(n=28):假手术组(S组)、骨癌病组(B组)和艾芬地尔2.5μg、5μg、10μg组(I1-3组).I1-3组和B组于小鼠右侧股骨远端骨髓腔接种NCTC 2472溶骨性纤维肉瘤细胞,建立骨癌痛模型;S组不接种肿瘤细胞.I1～3组于接种肿瘤细胞后14 d分别鞘内注射艾芬地尔2.5、5、10 μg,B组和S组鞘内注射艾芬地尔溶媒.各组于接种肿瘤细胞前1 d、鞘内注射艾芬地尔或溶媒前1 h、注射后2、12和24 h(T1～5)时随机取7只小鼠测定机械痛阈和热痛阈,并于T2～5,时测定后断头处死,取L3～5脊髓,采用RT-PCR法测定脊髓组织NR2B mRNA的表达水平.结果 与S组比较,除I3,组T3时热痛阈差异无统汁学意义(P0.05)外,B组和I1～3组机械痛阈和热痛阈均降低(P<0.05),B组和I1组脊髓组织NR2B mRNA表达上调,I2组该指标表达下调(P<0.05);与B组比较,I2.3组机械痈阈和热痛阈升高,脊髓组织NR2B mRNA表达下调(P<0.05),I1组各时点以上指标差异均无统计学意义(P0.05);与I2组比较,I3组机械痛阈和热痛阈升高,脊髓组织NR2B mRNA表达下调(P<0.05).结论 鞘内注射艾芬地尔可通过阻断含2B亚基的NMDA受体缓解小鼠骨癌痛,并下凋脊髓组织NR2B mRNA的表达抑制痛敏反应.     

骨癌痛小鼠痛行为及脊髓背角磷酸化环磷酸腺苷反应元件结合蛋白和脑源性神经营养因子表达的改变

目的 通过观察骨癌痛小鼠痛行为学的变化,磷酸化环磷酸腺苷反应元件结合蛋白（phosphorylated cAMP response element binding protein,pCREB）和脑源性神经营养因子（brain-derived neurotrophic factor,BDNF）在脊髓背角中表达的变化,探讨pCREB和BDNF在骨癌痛产生和维持中的作用. 方法 52只雄性C3H/HeJ小鼠,采用随机数字表法分为骨癌痛组（T组）和假手术组（S组）,每组26例.T组小鼠右侧股骨骨髓腔内注射含2×10^5个纤维肉瘤细胞的20μl最小必须培养基（α-minimal essence medium,α-MEM）,而S组注入不含肿瘤细胞的20μ1α-MEM,分别于接种肿瘤细胞前1d、接种后第4、7、10、14、21天测定自发抬足次数（spontaneous lifting times,SLTs）和机械缩足阈值（paw withdrawal mechanical threshold,PWMT）.按照分组在相应时间点处死小鼠,用免疫印迹法测定小鼠L3～5脊髓背角pCREB和BDNF的蛋白表达水平. 结果 与术前基础值和S组比较：接种后7、10、14、21d,T组小鼠SLTs[（4.43±0.91）,（7.10±1.03）,（11.27±1.35）,（13.03±0.58）次]显著增加（P＜0.05）;接种后10、14、21 d,T组小鼠PWMT[（0.63±0.20）、（0.32±0.12）、（0.24±0.12）g]明显下降（P＜0.05）,脊髓背角pCREB[（3.78±0.58）、（3.92±0.46）、（4.92±0.37）]和BDNF[（2.13±0.31）、（2.88±0.15）、（2.58±0.41）]的表达显著增加（P＜0.05）. 结论 骨癌痛小鼠脊髓背角pCREB和BDNF表达增加,并且与痛行为学的改变具有相关性,提示其可能参与了骨癌痛的产生和维持.     

大麻素受体2激动剂JWH-015对骨癌痛大鼠脊髓背角磷酸化环磷酸腺苷反应元件结合蛋白的影响

目的探讨腹腔注射大麻素受体（cannabinoid receptor,CB）2激动剂对骨癌痛大鼠脊髓背角磷酸化环磷酸腺苷反应元件结合蛋白（phosphorylated cyclic AMP respons eclement binding protein,pCREB）表达的影响。方法运用随机数字表法将63只雌性SD大鼠分为3组：肿瘤给药组（J组,15只）、肿瘤对照组（D组,24只）和假手术对照组（S组,24只）。J组、D组的大鼠左侧胫骨上端骨髓腔被注入5μl Walker256大鼠乳腺癌细胞制备骨癌痛模型;S组则注入等量的生理盐水。在造模后第10天,J组腹腔注射JWH-015（100μg/500μ1）,D组、s组注射等量JWH-015溶剂二甲基亚砜（dimethylsulfoxide,DMSO）。每组大鼠于造模前1d,造模后4、7、10d,腹腔注射后2、6、24、48、72h,检测手术侧机械刺激缩足阈值（paw withdrawal mechanical threshold,pwMT）和行走痛行为学评分。D组和S组大鼠于造模后4、7d,J组、D组和S组大鼠于造模后10d及腹腔注射后6、24、72h,取脊髓腰膨大进行免疫印迹分析。结果与S组比较,J组和D组大鼠造模后7d PWMT开始降低（P〈0.05）,造模后10d行走痛行为学评分增加（P〈0.05）,脊髓背角pCREB表达水平于7、10d上调（P〈0.05）.与D组比较,腹腔注射JWH-015后24h,J组PWMT（8.7±1.6）g显著上升（P〈0.05）,行走痛行为学评分（1.0±0.6）分和pCREB的表达（0.56±0.10）明显下降（P〈0.05）。结论腹腔注射JWH-015可能通过下调脊髓背角pCREB的表达改善骨癌痛大鼠的痛行为。