OBJECTIVE: To establish the animal models of mandibular distraction osteogenesis in rabbits and study its osteogenetic mechanism. METHODS: The right mandibles just anterior to the first molars of 12 rabbits were performed osteotomies, and the mandibles were positioned with distractors. The left mandibles were control group without operation. After 1 week, the distractors were stretched 0.9 mm every day for 10 days progressively. One day, 2, 4, 8 weeks after distraction, the mandibles were studied with gross measurement, X-ray, and histological examination. RESULTS: The right mandible were lengthened 8.3 mm on average without bone nonunion and deformity healing. It was observed that the gaps between the distracted bone edges were first occupied by fibrous tissue. Two weeks after distraction, it was found that the gaps were bridged by callus in X-ray, the new bone and the normal bone could not be differentiated clearly after 8 weeks. In histological sections, there were collagen bundles in early distraction, then those collagen bundles were calcificated and become trabeculaes. No Cartilage was found during distraction. CONCLUSION: It suggests that the rabbit mandible can be lengthened by distraction osteogenesis, and the new bone is formed by intramembranous ossification.
Objective To review the research progress of the role of periosteum in distraction osteogenesis. Methods The related domestic and foreign literature about the role of periosteum in distraction osteogenesis in recent years was extensively reviewed, summarized, and the mechanism and influencing factors of periosteum during traction and osteogenesis were analyzed. Results The periosteum is rich in all kinds of cells (mesenchymal stem cells, osteoblasts, etc.), microvessel and various growth factors, which are necessary for the formation of new bone. It can promote the formation of new bone in the process of traction osteogenesis significantly. Conclusion The periosteum plays an important role in the progress of distraction osteogenesis.
Objective To investigate the effects of different mechanical stretch conditions on the differentiation of rat tendon stem cells (TSCs), to find the best uniaxial cyclic stretching for TSCs tenogenic differentiation, osteogenic differentiation, and adipogenic differentiation. Methods TSCs were isolated from the Achilles tendons of 8-week-old male Sprague Dawley rats by enzymatic digestion method and cultured. The TSCs at passage 3 were randomly divided into 5 groups: group A (stretch strength of 4% and frequency of 1 Hz), group B (stretch strength of 4% and frequency of 2 Hz), group C (stretch strength of 8% and frequency of 1 Hz), group D (stretch strength of 8% and frequency of 2 Hz), and group E (static culture). At 12, 24, and 48 hours after mechanical stretch, the mRNA expressions of the tenogenic differentiation related genes [Scleraxis (SCX) and Tenascin C (TNC)], the osteogenic differentiation related genes [runt related transcription factor 2 (RUNX2) and distal-less homeobox 5 (DLX5)], and the adipogenic differentiation related genes [CCAAT-enhancer-binding protein-α (CEBPα) and lipoprteinlipase (LPL)] were detected by real-time fluorescent quantitative PCR and the protein expressions of TNC, CEBPα, and RUNX2 were detected by Western blot. Results The mRNA expressions of SCX and TNC in group B were significantly higher than those in groups A, C, D, and E at 24 hours after mechanical stretch (P<0.05). The mRNA expressions of CEBPα and LPL in group D were significantly higher than those in groups A, B, C, and E at 48 hours after mechanical stretch (P<0.05). The mRNA expressions of RUNX2 and DLX5 in group C were significantly higher than those in groups A, B, D, and E at 24 hours after mechanical stretch (P<0.05). Western blot detection showed that higher protein expression of TNC in group B than group E at each time point after mechanical stretch (P<0.05), and the protein expression of CEBPα was significantly inhibited when compared with group E at 24 hours after mechanical stretch (P<0.05). At 24 hours after mechanical stretch, the protein expression of RUNX2 in group C was significantly higher than that in group E (P<0.05); and the protein expression of TNC was significantly lower than that in group E at 24 and 48 hours after mechanical stretch (P<0.05). At 48 hours after mechanical stretch, the protein expression of CEBPα was significantly increased and the protein expression of TNC was significantly decreased in group D when compared with group E (P<0.05), but no significant difference was found in the protein expression of RUNX2 between groups D and E (P>0.05). Conclusion The mechanical strain could promote differentiation of TSCs, and different parameter of stretch will lead to different differentiation. The best stretch condition for tenogenic differentiation is 4% strength and 2 Hz frequency for 24 hours; the best stretch condition for osteogenic differentiation is 8% strength and 1 Hz frequency for 24 hours; and the best stretch condition for adipogenic differentiation is 8% strength and 2 Hz frequency for 48 hours.
Objective To investigate whether combining use of platelet-rich plasma (PRP) and decalcified bone matrix (DBM) has synergistic action on promoting bone consol idation and heal ing. Methods Forty male New Zealand rabbits (weighing 2.2-2.8 kg) were randomly divided into 4 groups (n=10). The whole blood was extracted from the central aural artery and PRP was prepared with the Landesberg’s method. An 1 cm-defect was made below the tibiofibular joint of the lefttibia through osteotomy. In group A, defect was repaired by distraction osteogenesis (1 cm); in group B, defect was repaired with 0.5 cm DBM and then by distraction osteogenesis (0.5 cm); in group C, defect was repaired by distraction osteogenesis (1 cm) and local injection of 1 mL PRP; in group D, defect was repaired by 0.5 cm DBM combined with 1 mL PRP and then by distraction osteogenesis (0.5 cm). Then lengthening started at 7 days after operation, at a rate of 1 mm/day and 0.5 mm every time for 10 days (groups A and C) or for 5 days (groups B and D). After the lengthening, the consolidation was performed. The X-ray films were taken at 0, 12, 17, 27, and 37 days after operation. At 37 days after operation, the tibial specimens were harvested for Micro-CT scanning, three-dimensional reconstruction and biomechanical test. Results The X-ray films showed that new bone formation in groups B and C was obviously better than that in groups A and D at 37 days. The bone mineral density (BMD), bone mineral content (BMC), and bone volume fraction (BVF) of groups B and C were significantly higher than those of groups A and D (P lt; 0.05); the BMD and BMC of group C were significantly higher than those of group B (P lt; 0.05); the BVF had no significant difference between groups B and C (P gt; 0.05). There was no significant difference in BMD, BMC, and BVF between groups A and D (P gt; 0.05). The trabecula number (Tb.N) of group C was significantly more than that of other groups (P lt; 0.05), and the trabecula spacing (Tb.Sp) of group C was significantly smaller than that of other groups (P lt; 0.05), but no significant differencewas found among other groups (P gt; 0.05). There was no significant difference in the trabecula thickness among 4 groups (P gt; 0.05). The ultimate angular displacement had no significant difference among 4 groups (P gt; 0.05). The maximum torque of groups B and C was significantly higher than that of groups A and D (P lt; 0.05); the maximum torque of group C was significantly higher than that of group B (P lt; 0.05); no significant difference was found between groups A and D (P gt; 0.05). Conclusion In the rabbit bone defect/lengthening model, local injection of PRP can enhance bone consol idation effectively during consol idation phase. In normal distraction rate, DBM can promote bone consol idation during distraction osteogenesis. In the early stage of distraction osteogenesis, combining use of DBM and PRP can not further promote bone consolidation and healing.
ObjectiveTo evaluate the efficacy of single intravitreal injection of C3F8 in treating vitremacular traction (VMT) syndrome.MethodsA retrospective case series of 38 eyes of 36 patients affected with VMT syndrome in Department of Ophthalmology, Central Theater Command General Hospital from March 2016 to June 2017 were enrolled in this study. There were 16 males (16 eyes) and 20 females (22 eyes), with the mean age of 64.11±9.49 years and the mean courses of 151.55±127.87 days. All the patients received an intravitreal injection of 0.3 ml of 100% C3F8 within one week. The BCVA examination was performed using the international standard visual acuity chart, which was converted into logMAR visual acuity. The severity of metamorphopsia was detected using M-charts. The extent of vitreomacular adhesion (VMA), central macular thickness (CMT) and the status of ellipsoid zone (EZ) were assessed with spectral-domain OCT at baseline and each month after treatment. The average BCVA was 0.58±0.22. The mean horizontal metamorphopsia (MH) and vertical metamorphopsia (MV) were 0.34±0.30 and 0.50±0.42, respectively. The mean CMT was 415.15±89.59 μm. The mean horizontal VMA was 1168.68±400.61 μm (30 eyes with VMA≤1500 μm and 8 eyes with VMA＞1500 μm). The mean vertical VMA was 976.89±295.92 μm. There were 22 eyes with integrity EZ and 16 eyes without integrity EZ, 33 eyes with crystalline lens and 5 eyes with IOL. The mean follow-up time was 10.7 months. The differences in BCVA, MH, MV, CMT, the integrity of EZ before and after treatment were analyzed. The VMT release rates were assessed. The Spearman rank correlation analysis was performed to investigate the relationship of VMT release rates with the data at baseline.ResultsVitreomacular traction release occurred in 29 of 38 eyes by the final follow-up visit, the VMT release rate was 76.3%. VMT release occurred and the average time of VMT release occurred was 2.2 weeks. VMT persisted in 7 eyes, in the rest two eyes, one eye developed a retinal detachment and another eye formed macular hole, both eyes responded to vitrectomy. At 6 months after treatment, the average logMAR BCVA was 0.43±0.23, the mean MH and MV were 0.25±0.23 and 0.24±0.23, the mean CMT was 310.61±63.10 μm. Among 16 eyes without integrity EZ before treatment, there were 9 eyes with integrity EZ at 6 months after treatment. There were 16 eyes with integrity EZ and 9 Compared with baseline, the mean BCVA at 6 months after treatment was significantly increased (F=3.779, P=0.037), but the MV (F=4.958, P =0.003) and CMT (F=13.419, P＜0.001) were significantly decreased, the integrity of EZ was improved significantly (χ2=5.050, P=0.025). The VMT release correlated inversely with the extent of horizontal VMA, BCVA, and CMT at baseline (r=-0.514, -0.348, -0.429; P=0.009, 0.001, 0.038).ConclusionIntravitreal injection of C3F8 can induce a posterior vitreous detachment and release vitreomacular traction, it is an efficient and safe treatment for VMT syndrome. It can improve the visual acuity, metamorphopsia and foveal morphology in patients with VMT syndrome.
ObjectiveTo summarize the effectiveness of delayed skin-stretching device in treatment of skin and soft tissue defects.MethodsBetween December 2014 and December 2016, 10 cases of skin and soft tissue defects were treated with delayed skin-stretching device. There were 6 males and 4 females with an average age of 53 years (range, 42-64 years). The skin and soft tissue defects were caused by acute trauma in 6 cases. The incision could not be closed directly after making incisions because of osseous fascia syndrome in 3 cases. The skin soft tissue defect caused after huge carbuncle incision and drainage in 1 case. The defect located at thigh in 4 cases, lower leg in 3 cases, upper arm in 2 cases, back in 1 case. The defect area ranged from 10 cm×4 cm to 22 cm×12 cm. Pinch test was performed on the wound margin, which confirmed that the wound could not be closed directly.ResultsTension blisters were found in 3 cases during traction, and no complications such as impaired blood circulation or skin necrosis occurred in all cases. Skin defects closed directly after continuously stretching for 7-18 days. No skin graft or free flap repair was performed in all patients. The wound healed well after operation. All the 10 patients were followed up 5-8 months (mean, 6.5 months). There was no necrosis around the wound margin and the scar was linear. The sensation and function were not affected.ConclusionDelayed skin-stretching device is an effective method to treat skin and soft tissue defects, which has the advantages of simple operation, lower risk of operation, less complications, and reliable effectiveness.
Objective To investigate whether mechanical stretch stimulation affects the expression of the immediate early gene c-fos mRNA in rat Achilles-derived tendon stem cells (TSCs)in vitro. Methods TSCs were isolated from the Achilles tendons of 8 weeks old male Sprague Dawley rats by enzymatic digestion method and cultured for 3 passages. The TSCs were stimulated by a uniaxial cyclic stretching loading system under the condition of 1 Hz, respectively with 4% or 8% stretch intensity for 0, 5, 15, 30, 60, and 120 minutes. At each time point, TSCs were collected to detect c-fos mRNA expressions and to find the best time-point Tmax by real-time fluorescence quantitative PCR. Then, TSCs were simulated with 2%, 4%, 6%, 8%, or 12% stretch intensity for Tmax to observe the relative expressions of c-fos mRNA under different stretch intensities. Next, TSCs were stretched for 0, 5, or 15 minutes respectively and followed by incubation at relax status up to Tmax to observe the changes of c-fos mRNA expressions after short period stimulation. Finally, TSCs were stimulated with 4% or 8% stretch intensity respectively for 0, Tmax, or 120 minutes to detect the expressions of the tenogenic differentiation related genes [collagen type I, tenomodulin (TNMD)], the osteogenic differentiation related genes [runt related transcription factor 2 (Runx2), distal-less homeobox 5 (Dlx5)], and the adipogenic differentiation related gene [fatty acid binding protein 4 (FABP4)]. Results Under 4% or 8% stretch intensity, the relative expressions of c-fos mRNA significantly increased at 15 minutes (P<0.05), reached the maximum at 30 minutes (P<0.05), and returned to baseline at 60 minutes (P>0.05) when compared with expression at 0 minute. Therefore, Tmax was 30 minutes. The stretch intensity of 2% was enough to cause the expression of c-fos mRNA at 30 minutes, and the expression was significantly higher under the stretch intensity of 6%, 8%, and 12% than 2% and 4% (P<0.05). Even for a short period stimulation of 5 minutes, c-fos mRNA expression could still significantly increase at 30 minutes (P<0.05). The relative expressions of differentiation related genes at 30 and 120 minutes showed no significant difference when compared with the expression at 0 minute under 4% stretch intensity (P>0.05); but the relative expression of Runx2 gene significantly increased at 30 minutes, and the relative expressions of collagen type I, TNMD, Dlx5, and Runx2 increased at 120 minutes under 8% stretch intensity (P<0.05). Conclusion Mechanical stretch stimulation can affect the relative expression of the immediate early gene c-fos mRNA of rat Achilles-derived tendon stem cellsin vitro, and there is time- and intensity-dependence. It is suggested that the mechanical stimulation with different time or intensity may affect the differentiation of TSCs at early stage. This study is meaningful for the further study on TSCs intracellular mechanical signal transfer mechanism.
This study is aimed to investigate the effects of mechanical stretch on the expression of transforming growth factor-β1 (TGF-β1) and fibroblast growth factor-2 (FGF-2), and the signaling pathway in human bronchial epithelioid (16HBE) cells under mechanical stretch. Using loading device with flexible substrate (FX-4000T) to stretch 16HBE cells, we found that the stretching elongation was 15%, at frequency of 1 Hz, stretching for 0.5 h, 1 h, 1.5 h and 2 h. Choosing the higher expression of TGF-β1, FGF-2 and Ca2+ group to carry out intervention experiments, we used the cells pretreated with canonical transient receptor potential 1 (TRPC1) channel antagonist SKF96365, protein kinase C (PKC) inhibitor HA-100, and thereafter mechanical stretch to interpose. Compared with those in the blank control group, TGF-β1 and FGF-2' protein and mRNA, intracellular Ca2+ fluorescence intensity were higher, and the differences were statistically significant (P < 0.05) at the 4 time points, 0.5 h, 1 h, 1.5 h and 2 h. At 0.5 h, the increasing rate was the highest. TGF-β1 protein and mRNA, FGF-2 protein and mRNA, intracellular Ca2+ luorescence intensity in the stretch+SKF96365 and stretch+HA-100 intervented group were decreased, the differences were statistically significant than those in 0.5 h stretch group (P < 0.05) without intervention. The expression of TGF-β1, FGF-2 was up-regulated in 16HBE cells under mechanical stretch, PKC, TRPC1, and Ca2+ may participate in the signal path.