Control of dental-derived induced pluripotent stem cells through modified surfaces for dental application

Objective: The aim of this study is to investigate the behaviour of iPSc derived from dental stem cells in terms of initial adhesion, differentiation potential on differently surface-treated titanium disc.

Materials and methods: iPSc derived from human gingival fibroblasts (hGFs) were established using 4-reprogramming factors transduction with Sendai virus. The hGF-iPSc established in this study exhibited the morphology and growth properties similar to human embryonic stem (ES) cells and expressed pluripotency makers. Alkaline Phosphatase (AP) staining, Embryoid Body (EB) formation and in vitro differentiation and karyotyping further confirmed pluripotency of hGF-iPSc. Then, hGF-iPSc were cultured on machined- and Sandblasted and acid etched (SLA)-treated titanium discs with osteogenic induction medium and their morphological as well as quantitative changes according to different surface types were investigated using Alizrin Red S staining, Scanning electron microscopy (SEM), Flow cytometry and RT-PCR.

Results: Time-dependent and surface-dependent morphological changes as well as quantitative change in osteogenic differentiation of hGF-iPSc were identified and osteogenic gene expression of hGF-iPSc cultured on SLA-treated titanium disc found to be greater than machined titanium disc, suggesting the fate of hGF-iPSc may be determined by the characteristics of surface to which hGF-iPSc first adhere.

Conclusions: iPSc derived from dental stem cell can be one of the most promising and practical cell sources for personalized regenerative dentistry and their morphological change as well as quantitative change in osteogenic differentiation according to different surface types may be further utilized for future clinical application incorporated with dental implant.     

Molecular Outcome,Prediction, and Clinical Consequences of Splice Variants in COL1A1, Which Encodes the proα1(I) Chains of Type I Procollagen

Approximately 10%–20% of germline pathogenic variants alter mRNA splicing, with phenotypes often dependent on the stability of the mRNA produced by the mutant allele. To better understand the relationships between genotype, mRNA splicing, and phenotype, we examined clinical and molecular data from 243 probands with osteogenesis imperfecta (OI) representing 145 unique splicing variants within the type I procollagen gene, COL1A1. All individuals with IVSX‐1G>A mutations had OI type I because the substitution shifted the splice acceptor site 1 nt downstream and destabilized the mRNA. OI phenotypes were not consistent for any other splice variant identified. We sequenced all cDNA species from cultured dermal fibroblasts from 40 individuals to identify splice outcome and compared those results to splice predictions from Human Splice Finder (HSF), Spliceport (SP), and Automatic Splice Site and Exon Definition Analyses (ASSEDA). Software‐based splice predictions were correct in 42%, 55%, and 74% instances for HSF, SP, and ASSEDA, respectively. As molecular diagnostics move increasingly to DNA sequence analysis, the need to understand the effects of splice site variants will increase. These data demonstrate that caution must be exercised when using splice prediction software to predict splice outcome.     

Combined magnetic fields accelerate bone‐tendon junction injury healing through osteogenesis

The objective of this study was to explore the effect of combined magnetic fields (CMFs) on osteogenesis and the remodeling of newly formed bone at bone‐tendon (BT) junction. Forty‐eight mature rabbits in whom partial patellectomy was performed were used to establish a BT junction injury model at the patella‐patellar tendon (PPT) complex and were then allocated to CMF treatment group (CMF group) or placebo treatment group (control group). Daily CMF therapy was delivered continuously from post‐operative day 3 to weeks 4, 8, and 16. At each time point, the animals were sacrificed, and the PPT complexes were harvested for radiographic, histological, peripheral quantitative computed tomography, and micro‐computed tomography (micro‐CT) evaluation. The area, length, and bone mineral density of the newly formed bone in the CMF group were significantly greater than the control group at post‐operative weeks 8 and 16. The micro‐CT results showed that the newly formed bone in the CMF group contained more and thicker trabeculae than the control group at weeks 8 and 16. Histologically, the CMF group showed better remodeling of the BT junction. In conclusion, CMF treatment was able to accelerate osteogenesis during BT junction repair, thus facilitating the healing of BT junction injury.     

Reconstruction by bone transport after resection of benign tumors of tibia: A retrospective study of 38 patients

Background:

The commonly used reconstructive options after post resection defects in bone tumors like megaprosthesis, autograft, allograft, bone graft substitutes and recycled bone have their own demerits on a long term. Bone transport that regenerates patient''s own bone is a less explored option of reconstruction after resection of benign bone tumors and reports on this are limited. This technique is very much relevant in tibia where Ilizarov fixator is surgeon and patient friendly. We report our experience.

Materials and Methods:

This is a retrospective series of resection and bone transport in 38 patients with benign tumor of tibia. There were 14 males and 24 females with mean age of 23.40 years (range 9–40 years). Lesion was located in proximal third tibia in 27, middle third in two and distal third in nine patients. The diagnosis was giant cell tumor in 32, chondroblastoma in three, chondromyxoid fibroma, enchondroma and desmoplasic fibroma in one patient each. The resection was intercalary in 28 and transarticular in 10 patients. Osteosynthesis was monofocal in three, bifocal in 31 and polyfocal in four cases.

Results:

Mean followup was 7.22 years (range 1.5–15 years). Mean resection length was 10.21 cm (range 3–22 cm). The mean duration of external fixator was 308.03 days (range 89–677 days) and mean external fixator index was 36.14 days/cm (range 16.84–97.43 days/cm). Twelve patients had difficulties in the form of 11 problems and five obstacles that were successfully managed. None of the patients had local recurrence of tumor or any long term complication. Mean Musculo-skeletal Tumour Society score at final followup was 27.18 (90.60%).

Conclusions:

Bone transport is an excellent option after resection of benign tumors of tibia with good local control and functional outcome, despite minor difficulties that need timely management.     

Comparative study of the results of compound tibial shaft fractures treated by Ilizarov ring fixators and limb reconstruction system fixators

Purpose: Ilizarov ring fixator and limb reconstruction system (LRS) fixators have been used in the management of complex tibial fractures with severe soft tissue injuries, compound tibial fractures, and infected tibial nonunion for which conventional internal fixation cannot be contemplated. Fracture union and distraction osteogenesis can be done simultaneously with these external fixators, allowing early weight bearing. Several previous studies have shown almost equal results of rail and ring fixators for the compound tibial shaft fractures. Thus we performed a prospective study to evaluate the union rate, functional outcome and amount of limb lengthening after the treatment of compound tibial shaft fractures with or without infected nonunion by ring or LRS fixators. Methods: This prospective study was done at Sarojini Naidu Medical College and Hospital, Agra, India and included 32 patients of compound tibial shaft fractures with or without infected nonunion. There were 26 males and 6 females and the average age was 40 years. Patients were randomly divided into two groups (n=16 for each): one underwent Ilizarov fixation and the other received LRS fixation. Cases were followed up for 3e24 months, 6 months on average from September 2012 to October 2014. Functional and radiological outcomes were assessed using the Association for the Study and Application of Methods of Ilizarov (ASAMI) criteria for both rail and ring fixators. Results: Union was achieved in all cases. Radiological outcome was found excellent in 68.75%, good in 18.75% and fair in 12.50% of cases treated by rail fixators whereas it was excellent in 56.25%, good in 18.75%, fair in 12.50% and poor in 12.50% of cases treated by ring fixators. Functional result was satisfactory in 75.00% of cases treated by rail fixator and 68.75% of cases treated by ring fixators whereas the corresponding rate of unsatisfactory was 25.00% vs. 31.25%. Conclusion: In our short-term assessment, LRS fixators show a better result than Ilizarov fixators in terms of fracture union and functional outcome with soft tissue care and limb length.     

不同剂量阿司匹林对大鼠钛合金种植体早期骨整合的影响

目的探讨不同剂量阿司匹林对大鼠股骨钛合金种植体早期骨整合的影响,为临床使用阿司匹林患者的牙种植提供参考。方法48只8周龄SD雄性大鼠随机分为对照组和实验组(A、B、C组),每组12只,分别于右侧股骨干骺端植入直径1.4mm,长度6 mm的Ti 6Al 4V种植钉一枚。术后分别给予实验组A、B、C组8.93 mg/kg/d、17.86 mg/kg/d、26.79 mg/kg/d阿司匹林灌胃,对照组给予等剂量0.9%的氯化钠注射液灌胃至2周、4周。各组分别于术后2周、4周对种植区进行HE、Masson、BMP 2免疫组织化学及TRAP染色检测。结果HE染色结果显示,B、C组较对照组种植体周围新骨形成量降低,骨小梁稀疏,骨髓腔增大,且C组最明显,对照组与A组无明显差异;Masson染色结果显示,B、C组较对照组种植体周围新生骨组织中红染区域减少,且C组减少更明显,A组则与对照组未见明显差异;BMP 2免疫组织化学染色结果显示,A组与对照组BMP 2表达量差异无统计学意义(P>0.05),C组较其余组BMP 2表达量降低(P<0.05);TRAP染色结果显示,对照组、A、B、C组TRAP单位面积阳性染色个数依次降低,差异具有统计学意义(P<0.05)。结论阿司匹林可能通过抑制成骨细胞的形成和活性及破骨细胞的表达来减少骨组织的形成,且与剂量相关,高剂量的阿司匹林抑制成骨作用更明显。