Pulsing electromagnetic field stimulation of the in vitro growth plate

Specific pulsing electromagnetic fields (PEMFs) have been used to stimulate growth and repair of osteogenic tissues; however, the basis for this specificity is unknown. Previously, we determined the relevant electromagnetic field parameters of the clinically used PEMF and independently verified the beneficial effects of PEMFs on the rabbit fibula fracture healing model. The goal of the present study was to develop an in vitro model that would permit the effectiveness of various electric and magnetic field components of the PEMF to be determined. The costochondral junction (CCJ) of the 21-day-old rat was exposed in vitro to PEMFs with various electric and magnetic field component amplitudes. Response of this model to PEMFs was determined by nondestructive macrophotographic measurement of CCJ growth. Preliminary data indicated that temperature effects were present in this in vitro system. Subsequent experiments designed to separate the effects of temperature and PEMFs on the growth of CCJs in tissue culture were performed. Results indicate that accurate and frequent temperature measurements must be made for in vitro models being used to study effects of PEMFs. Small temperature differences induced by the coils used to produce PEMFs in the CCJ experimental system can have significant stimulatory effects, and the combined effects of temperature and PEMFs are not linearly additive in this model. Furthermore, our results suggest that thermal and PEMF stimuli could affect macrophotographically measured growth of the CCJ by separate mechanisms or could have a synergistic effect. Therefore, PEMF stimulation experiments should be performed under strictly "athermal" conditions.     

The vascular ‘sunburst’ appearance of osteosarcoma: A new angiographic finding

The angiographic analogue of the sunburst, (right angle) periosteal new bone formation in osteogenic sarcoma is described. The angiographic findings in this tumor and their relationship to the pathologic appearance are discussed.     

Osteosarcoma of the Head and Neck: Meta-analysis of Nonrandomized Studies

To assess the role of adjuvant therapy in the treatment of osteogenic sarcoma of the head and neck, treatment and survival information from 173 patients with osteosarcoma of the head and neck was entered into a database. A meta-analysis of the data was attempted with primary emphasis on the effect of adjuvant therapy on disease outcome. The overall 5-year survival was 37%. Patients with mandibular and maxillary tumors had similar survival rates; both groups fared significantly better than patients with extragnathic tumors (P<0.001). Treatment with surgery alone was associated with significantly longer survival rates (P<0.03) than surgery with adjuvant therapy. In the majority of patients reported, information about surgical margins was not available. For this reason, the differences may not adequately represent the effect of adjuvant therapy. While there have been encouraging results with adjuvant treatment protocols for long bone osteosarcoma, the ultimate role of radiation and chemotherapy in the management of osteosarcoma of the head and neck remains unproven. Nevertheless, we recommend that adjuvant therapy be considered due to the poor prognosis in osteosarcoma of the head and neck.     

Tumors of the rib

The authors propose a pictorial review illustrating the imaging features of chest wall tumors and their specific features that discusses the main differential diagnoses. This review is based on published information and on our own experience.     

Comparison of osteoblast and cardiomyocyte differentiation in the embryonic stem cell test for predicting embryotoxicity in vivo

One of the most studied alternative embryotoxicity assays is the embryonic stem cell test, in which the effect of compounds on cardiomyocyte differentiation is evaluated (subsequently termed the ESTc). This single differentiation endpoint may limit the predictive value of the assay. We recently published a novel embryonic stem cell based osteoblast differentiation assay (subsequently termed the ESTo), in which we studied the effect of six embryotoxic compounds. Differentiation is monitored via the differential expression of three genes related to osteogenesis (Runx2, SPARC and collagen type I). In the current study, we evaluated the effect of 14 additional compounds in the ESTo, to assess its added value as compared to the ESTc. To this end, we compared the effects of the compounds in the ESTo to their effects in the ESTc and to their published in vivo developmental toxicity profiles. The results show that there is a high overall correlation between compound potencies as regards inhibition of osteoblast and cardiomyocyte differentiation. Moreover, the results in both the ESTo and ESTc showed a significant correlation to in vivo developmental toxicity potency ranking of compounds tested. Interestingly, the embryotoxic effect of TCDD could only be detected using the ESTo, which can be explained based on its mechanism of action and its known inhibitory effect on osteogenesis. The results of TCDD suggest that incorporating the ESTo into a testing battery together with the ESTc could improve the overall predictive value of the battery.     

动态轴向压应变促进丝素蛋白支架内MC3T3-E1细胞成骨分化

目的 观察动态轴向压应变对三维丝素蛋白支架内成骨细胞成骨相关基因表达的影响。方法 应用动态力学加载仪对实验组小鼠胚胎成骨细胞MC3T3-E1加载动态轴向压应变（5%应变幅度,1 Hz,30 min/d,共21 d）,对照组细胞常规静置培养,不施加力学刺激。应用定量PCR检测细胞成骨基因碱性磷酸酶（ALP）、I型胶原（COLⅠ）、骨特异性转录因子（Runx2）、成骨相关转录因子（Osx）、骨钙蛋白（OCN） mRNA表达量。结果 成骨细胞在周期性轴向压应力刺激下,Runx2、Osx及COLⅠ表达分别增加280%、68.9%和79.6%,ALP及OCN表达也分别增加10.7%和26.9%。实验组成骨相关基因mRNA表达与对照组比较,差异具有统计学意义（P<0.05）。结论 成骨细胞复合丝素蛋白生物支架材料在周期性轴向压应力刺激下,成骨基因COLⅠ、Runx2、Osx及OCN表达明显上调,可能是生理状态下压应力刺激促进骨折愈合的重要机制之一。研究结果对于以力学信号为基础的细胞疗法修复骨缺损等疾病具有重要临床价值。     

大鼠脂肪干细胞的体外分离培养及对脂肪颗粒移植的影响

目的分析体外大鼠脂肪干细胞(ADSCs)混合脂肪移植后的存活情况。方法无菌条件下切取大鼠腹股沟脂肪组织,消化、分离培养得到第3代ADSCs,行成骨诱导(茜素红染色)和成脂诱导(油红O染色)。用CM-Dil荧光标记第3代ADSCs,24只大鼠每只背部皮下3处分别植入1.5ml脂肪颗粒、1.5ml荧光标记的ADSCs(密度为5×107个细胞/ml)和0.9ml荧光标记的ADSCs+0.6ml脂肪颗粒。术后2周、1个月和3个月每次取出8只大鼠的移植物,石蜡切片HE染色观察病理变化,冰冻切片荧光显微镜下观察ADSCs定位。结果 ADSCs成骨诱导2周后茜素红染色阳性,成脂诱导3周后油红O染色阳性。ADSCs与脂肪颗粒混合移植能明显改善脂肪组织的病理学变化。结论体外分离培养的大鼠ADSCs具有成骨、成脂分化的潜能,能改善脂肪颗粒移植时的脂肪组织的液化吸收现象。