Comparison of adipose stem cells sources from various locations of rat body for their application for seeding on polymer scaffolds

Adipose tissue yields adult adipose stem cells (ASCs) in large quantities via less-invasive methods. These cells are of interest owing to their modulating properties and paracrine activities, which can be harnessed in regenerative medicine. Many studies on the use of rat fat tissue in an autologous animal model have been conducted; however, the different locations to obtain stromal vascular fraction of rat fat depots have not been fully characterized. The purpose of the current study was to identify optimal source of ASC from various locations of rat body. Animal experiments in vitro revealed that fat depots from cervical fat are an optimal ASC source. A high ASC yield facilitates subsequent studies on autologous transplantation in rats. The secondary objective was to compare the efficiency of osteoinductive media composition and evaluate of osteogenic potential of ASCs for seeding on scaffolds for bone repair. Scaffolds were assessed in vitro, using rat adipose stem cells and three-dimensional (3D) scaffolds comprising polycaprolactone (PCL) or polycaprolactone covered with tricalcium phosphate (PCL + 5%TCP). Seeded ASCs adhere to the surface and migrate to the scaffolds. Upon staining and determining alkaline phosphatase levels, PCL + 5%TCP scaffolds performed better than PCL scaffolds. Furthermore, growth factors such as BMP2 and FGF2 significantly increased ASC mineralization and induced osteogenesis (p?<?0.05). Our results may help select and develop pre-clinical animal model for confirming the use of ASC, alone or in association with appropriate biomaterials for bone repair.     

复合rhBMP2的异种骨的研制及成骨活性

目的：研制新型具有诱导成骨活性的异种骨植骨材料。方法：在重组合异种骨（RBX）基础上,以基因重组人BMP2（rhBMP2）取代从牛皮质骨中提取的牛BMP,与去抗原牛松质骨载体（BCB）复合,制成复合rhBMP2的异种骨（rhBMP2/BCB）,并采用小鼠股部肌袋模型,通过组织学、骨计量学方法检测rhBMP2/BCB的诱导成骨活性。结果：实验组（rhBMP2/BCB组）术后7d在小鼠肌袋可诱导软骨生成,14d形成纺织骨,21d改建成板状骨并形成大量骨髓;对照组（BCB组）于术后各时间点均未见有软骨成骨形成。实验组的碱性磷酸酶活性和钙含量均高于对照组,有非常显性差异（P＜0．01）。结论：rhBMP2/BCB具有较好的骨诱导能力,是一种较理想的植骨材料。     

采用骨内型牵张器建立垂直向牙槽骨牵张成骨动物模型

【目的】应用自行研制的骨内型牙槽骨牵张器,建立犬垂直向牙槽骨牵张成骨动物模型。【方法】实验动物为中山大学动物中心提供的健康成年杂种犬12只。实验材料为自行设计,纯钛制成的骨内型垂直向牙槽骨牵张器,体部直径3.75mm,长5mm。先拔除犬双侧下颌前磨牙,形成萎缩牙槽嵴的模型。3月后随机选取一侧行骨切开术,植入两枚牵张器。1周后开始牵张,每天1次,每次1mm,共5d;分别在牵张后1、2和3月将动物处死进行临床检查,X线检查和组织学检查。【结果】骨内型垂直牙槽骨牵张器愈合良好。牙槽骨高度平均增加(4.8±0.50)mm。组织学切片显示在牵张区有骨质形成,其骨小梁方向与牵引方向一致。【结论】采用该骨内型牙槽骨牵张器成功建立稳定的、重复性好的犬牙槽骨牵张成骨动物模型,为牙槽骨牵张器的国产化和临床上应用该项技术打下基础。     

Transient serum exposure regimes to support dual differentiation of human mesenchymal stem cells

Human mesenchymal stem cells (MSCs), which can generate both osteoblasts and chondrocytes, represent an ideal resource for orthopaedic repair using tissue‐engineering approaches. One major difficulty for the development of osteochondral constructs using undifferentiated MSCs is that serum is typically used in culture protocols to promote differentiation of the osteogenic component, whereas existing chondrogenic differentiation protocols rely on the use of serum‐free conditions. In order to define conditions which could be compatible with both chondrogenic and osteogenic differentiation in a single bioreactor, we have analysed the efficiency of new biphasic differentiation regimes based on transient serum exposure followed by serum‐free treatment. MSC differentiation was assessed either in serum‐free medium or with a range of transient exposure to serum, and compared to continuous serum‐containing treatment. Although osteogenic differentation was not supported in the complete absence of serum, marker expression and extensive mineralization analyses established that 5 days of transient exposure triggered a level of differentiation comparable to that observed when serum was present throughout. This initial phase of serum exposure was further shown to support the successful chondrogenic differentiation of MSCs, comparable to controls maintained in serum‐free conditions throughout. This study indicates that a culture based on temporal serum exposure followed by serum‐free treatment is compatible with both osteogenic and chondrogenic differentiation of MSCs. These results will allow the development of novel strategies for osteochondral tissue engineering approaches using MSCs for regenerative medicine. Copyright © 2012 John Wiley & Sons, Ltd.     

Ilizarov bone transport after massive tibial trauma: Case report

IntroductionThis is a case report of extreme lengthening of the tibia of about 14.5 cm using bone transport technique following road traffic accident trauma to the lower limbs. The management of the subsequent massive skeletal defects was challenging to orthopedic surgeons. Based on reported cases, the highest tibial lengthening was 22 cm using bifocal transport, while the highest unifocal tibial lengthening reached 14.5 cm.Case presentationA 20-year-old male driver was brought to the emergency department after a road traffic accident. The patient had a right Gustilo IIIA segmental open tibia fracture with bone loss and other severe injuries. The tibial defect was 14.5 cm and the patient was then admitted for Ilizarov application six months after the accident. Although this case was particularly complicated, full limb length was restored.DiscussionThe management of this case was directed to correct the deformities and achieve equal length of both limbs to restore the normal function. Several new techniques have been developed recently to fill large bone defects. Limb lengthening using bone transport technique by application of Ilizarov ring fixator has been suggested as the leading option in filling massive bone gaps.ConclusionThe use of bone transport technique using Ilizarov external rings has proved to be a minimally invasive and reliable method in managing massive bone defects. Accurate application of the Ilizarov frame and proper transport of the middle segment are important factors alleviating the risk for deviation of the transported segment. However, due to the need for regular follow-ups and monitoring, it demands high compliance from the patient to achieve optimal results.     

Two-stage maxillary distraction osteogenesis using a modified external device: clinical outcome and complications

Rigid external distraction is currently used to correct severe maxillary hypoplasia. The purpose of this retrospective study was to present the clinical results and complications of a two-stage surgical approach using a modified external distraction system that consists of maxillary distraction and then maxillary fixation. We treated eight patients with cleft lip and palate in this way from 2016 to 2018. Lateral cephalograms taken before the first operation, after distraction, two weeks after the second operation, and one year after treatment were used to examine maxillofacial morphology. Velopharyngeal function was evaluated by a speech therapist. The mean movements of the maxilla forwards and downwards at Point A were 12.0 mm and 8.0 mm at the completion of distraction and those at Point B were 5.0 mm backwards and 9.7 mm downwards. Mouth opening was limited at this time, and was relieved after maxillary fixation. The mean relapse one year postoperatively was 24.3% horizontally and 52.5% vertically. Velopharyngeal function was unchanged by the operation. We conclude that the method has advantages that include the short duration of wearing distractors and increased acceptance by patients. The modified external device advanced the midface sufficiently.