Objective To discuss the role of heparan sulfate (HS) in bone formation and bone remodeling and summarize the research progress in the osteogenic mechanism of HS. Methods The domestic and abroad related literature about HS acting on osteoblast cell line in vitro, HS and HS composite scaffold materials acting on the ani-mal bone defect models, and the effect of HS proteoglycans on bone development were summarized and analyzed. Results Many growth factors involved in fracture healing especially heparin-binding growth factors, such as fibroblast growth factors, bone morphogenetic protein, and transforming growth factor β, are connected noncovalently with long HS chains. HS proteoglycans protect these proteins from protease degradation and are directly involved in the regulation of growth factors signaling and bone cell function. HS can promote the differentiation of stem cells into osteoblasts and enhance the differentiation of osteoblasts. In bone matrix, HS plays a significant role in promoting the formation, maintaining the stability, and accelerating the mineralization. Conclusion The osteogenesis of HS is pronounced. HS is likely to become the clinical treatment measures of fracture nonunion or delayed union, and is expected to provide more choices for bone tissue engineering with identification of its long-term safety.
Based on transversely isotropic theory, a finite element model for three-dimensional solid-liquid coupling defect repair of articular cartilage was established. By studying stress state of host cartilage near the restoration interface, we identified deformation type of cartilage and discussed the cause of restoration interface cracking. The results showed that the host cartilage surface node near the restoration interface underwent compression deformation in the condition of surface layer defect repair. When the middle layer, deep layer or full-thickness defect were repaired, the node underwent tensile deformation. At this point, the radial dimension of cartilage increased, which might cause restoration interface cracking. If elastic modulus of the tissue engineered cartilage (TEC) was lower (0.1 MPa, 0.3 MPa), the host cartilage surface layer and middle layer mainly underwent tensile deformation. While elastic modulus of TEC was higher (0.6 MPa, 0.9 MPa), each layer of host cartilage underwent compression deformation. Therefore, the elastic modulus of TEC could be increased properly for full-thickness defect repair. This article provides a new idea for evaluating the effect of cartilage tissue engineering repair, and has a certain guiding significance for clinical practice.
Objective To investigate the role and regulatory mechanism of ring finger protein 11 (RNF11) on Akt signaling pathway in the process of osteogenesis of bone marrow mesenchymal stem cells (BMSCs) to provide ideas for further clarifying its osteogenesis mechanism and its use in clinical treatment in the future. Methods BMSCs were isolated and cultured from fresh bone marrow of healthy donors and subcultured. The 4th generation cells were used in experiments after identification by flow cytometry, and osteogenic, chondrogenic, and adipogenic induction. BMSCs were cultured in osteogenic differentiation medium for 0-14 days. The degree of osteogenic differentiation was detected by Alizarin red staining and alkaline phosphatase (ALP) staining, and the protein expression of RNF11 was detected by Western blot. The 4th generation BMSCs were divided into blank control group (group A), empty lentivirus (Lv-NC) group (group B), and knockdown RNF11 (Lv-ShRNF11) group (group C). Osteogenesis was induced and cultured for 0-14 days. The expression of RNF11 protein was detected by Western blot, the degree of osteogenic differentiation was detected by Alizarin red staining and ALP staining, and the relative mRNA expressions of Runx2, osteocalcin (OCN), and osteopontin (OPN) were detected by real-time fluorescence quantitative PCR (qRT-PCR). The protein relative expressions of Akt, Smad1/5/8, and β-catenin signaling pathway were detected by Western blot, expressed as the ratio before and after phosphorylation. In order to study the effect mechanism of RNF11 on Akt signaling pathway, the 4th generation BMSCs were divided into Lv-NC transfection group (group A1), Lv-ShRNF11 transfection group (group B1), and Lv-ShRNF11 transfection supplemented with Akt signaling pathway activator SC79 group (group C1). The protein relative expressions of RNF11 and Akt signaling pathway were detected by Western blot, the related osteogenesis indexes were detected by Alizarin red staining, ALP staining, and qRT-PCR. ResultsThe flow cytometry, and osteogenic, chondrogenic, adipogenic induction culture identification showed that the isolated and cultured cells were BMSCs. The protein relative expression of RNF11 increased gradually with the extension of osteogenic differentiation time (P<0.05); after knockdown RNF11, Alizarin red and ALP stainings showed that the degree of osteogenic differentiation of BMSCs in group C were significantly lower than those in groups A and B, and qRT-PCR detection showed that the relative expression of Runx2, OCN, and OPN mRNA significantly decreased (P<0.05). The protein relative expressions of RNF11 and Akt signaling pathway significantly increased with the extensions of osteogenic differentiation time (P<0.05). After knockdown RNF11, the protein relative expression of Akt signaling pathway in group C was significantly lower than that in groups A and B (P<0.05), while Smad1/5/8 and β-catenin signaling pathway had no significant effect (P>0.05). Compared with group A1, the protein relative expression of RNF11 in groups B1 and C1 significantly decreased (P<0.05). Compared with groups A1 and C1, the protein relative expression of Akt signaling pathway in group B1 was significantly lower (P<0.05); Alizarin red and ALP stainings showed that the degree of osteogenic differentiation of BMSCs in group C1 were slightly lower than that of group A1 (P>0.05), but significantly higher than that of group B1 (P<0.05); qRT-PCR detection showed that the relative expressions of Runx2, OCN, and OPN mRNA in group C1 were slightly lower than those of group A1 (P>0.05), but were significantly higher than those of group B1 (P<0.05). ConclusionRNF11 promotes the differentiation of BMSCs into osteoblasts by positively regulating the activation level of Akt signaling pathway. RNF11 can be used as a potential target to improve the bone repair efficacy of BMSCs and treat bone metabolic diseases.
ObjectiveTo investigate the effects of micro-fracture and insul in-l ike growth factor 1 (IGF-1) in treatment of articular cartilage defect in rabbits. MethodsTwenty-four New Zealand white rabbits (aged, 4-6 months; weighing, 2.5-3.5 kg) were randomly divided into 4 groups (n=6):micro-fractures and recombinant human IGF-1 (rhIGF-1) treatment group (group A), micro-fracture control group (group B), rhIGF-1 treatment control group (group C), and blank control group (group D). Full thickness articular cartilage defects of 8 mm×6 mm in size were created in the bilateral femoral condyles of all rabbits. The micro-fracture surgery was performed in groups A and B. The 0.1 mL rhIGF-1 (0.01 μg/μL) was injected into the knee cavity in groups A and C at 3 times a week for 4 weeks after operation, while 0.1 mL sal ine was injected in groups B and D at the same time points. At 4, 12, and 24 weeks, the gross, histological, and immunohistochemical observations were performed, and histological score also was processed according to Wakitani's score criteria. The collagen contents in the repair tissues and normal patellofemoral cartilage were detected by the improved hydroxyproline (HPR) method at 24 weeks. Electron microscope was used to observe repair tissues of groups A and B at 24 weeks. Results All animals were survival at the end of experiment. At 24 weeks after operation, defect was repaired with time, and the repair tissue was similar to normal cartilage in group A; the repair tissue was even without boundary with normal cartilage in group B; and the repair tissue was uneven with clear boundary with normal cartilage in groups C and D. Histological staining showed that the repair tissues had no difference with normal cartilage in group A; many oval chondrocytes-l ike cells and l ight-colored matrix were seen in the repair tissues of group B; only a few small spindle-shaped fibroblasts were seen in groups C and D. Moreover, histological scores of group A were significantly better than those of groups B, C, and D (P<0.05) at 4, 12, and 24 weeks. Electron microscope observation showed that a large number of lacuna were seen on the surface of repair tissue in group A, and chondrocytes contained glycogen granules were located in lacunae, and were surrounded with the collagen fibers, which was better than that in group B. Collagen content of the repair tissue in group A was significantly higher than that in groups B, C, and D (P<0.05), but it was significantly lower than that of normal cartilage (P<0.05). Conclusion Combination of micro-fracture and rhIGF-1 for the treatment of full thickness articular cartilage defects could promote the repair of defects by hyaline cartilage.
ObjectiveTo review the methods of improving the mechanical properties of hydrogels and the research progress in bone tissue engineering. MethodsThe recent domestic and foreign literature on hydrogels in bone tissue engineering was reviewed, and the methods of improving the mechanical properties of hydrogels and the effect of bone repair in vivo and in vitro were summarized. ResultsHydrogels are widely used in bone tissue engineering, but their mechanical properties are poor. Improving the mechanical properties of hydrogels can enhance bone repair. The methods of improving the mechanical properties of hydrogels include the construction of dual network structures, inorganic nanoparticle composites, introduction of conductive materials, and fiber network reinforcement. These methods can improve the mechanical properties of hydrogels to various degrees while also demonstrating a significant bone repair impact. ConclusionThe mechanical properties of hydrogels can be effectively improved by modifying the system, components, and fiber structure, and bone repair can be effectively promoted.
ObjectiveTo investigate the feasibility of tissue engineered periosteum (TEP) constructed by porcine small intestinal submucosa (SIS) and bone marrow mesenchymal stem cells (BMSCs) of rabbit to repair the large irregular bone defects in allogenic rabbits. MethodsThe BMSCs were cultivated from the bone marrow of New Zealand white rabbits (aged, 2 weeks-1 month). SIS was fabricated by porcine proximal jejunum. The TEP constructed by SIS scaffold and BMSCs was prepared in vitro. Eighteen 6-month-old New Zealand white rabbits whose scapula was incompletely resected to establish one side large irregular bone defects (3 cm×3 cm) model. The bone defects were repaired with TEP (experimental group,n=9) and SIS (control group,n=9), respectively. At 8 weeks after operation, the rabbits were sacrificed, and the implants were harvested. The general condition of the rabbits was observed; X-ray radiography and score according to Lane-Sandhu criteria, and histological examination (HE staining and Masson staining) were performed. ResultsAfter operation, all animals had normal behavior and diet; the incision healed normally. The X-ray results showed new bone formation with normal bone density in the defect area of experimental group; but no bone formation was observed in control group. The X-ray score was 6.67±0.32 in experimental group and was 0.32±0.04 in control group, showing significant difference (t=19.871,P=0.001). The general observation of the specimens showed bone healing at both ends of the defect, and the defect was filled by new bone in experimental group; no new bone formed in the control group. The histological staining showed new bone tissue where there were a lot of new vessels and medullary cavity, and no macrophages or lymphocytes infiltration was observed in the defect area of experimental group; only some connective tissue was found in the control group. ConclusionTEP constructed by porcine SIS and BMSCs of rabbit can form new bone in allogenic rabbit and has the feasibility to repair the large irregular bone defects.
Objective To evaluate the effectiveness of the submental island flap for repair of oral defects after radical resection of early-stage oral squamous cell carcinoma (OSCC). Methods Between February 2010 and August 2011, 15 cases of early-stage OSCC were treated. Of 15 cases, 9 were male and 6 were female, aged from 48 to 71 years (mean, 63 years). The disease duration was 28-73 days (mean, 35 days). Primary lesions included tongue (3 cases), buccal mucosa (8 cases), retromolar area (2 cases), and floor of mouth mucosa (2 cases). According to TNM classification of International Union Against Cancer (UICC, 2002) of oral cancer and oropharyngeal cancer, 2 cases were classified as T1N0M0 and 13 cases as T2N0M0. The results of the pathologic type were high differentiated squamous cell carcinoma in 11 cases and moderately differentiated squamous cell carcinoma in 4 cases. The defect after resection of the lesion ranged from 5 cm × 3 cm to 8 cm × 6 cm. All the cases underwent radical resection of the primary lesion and immediate reconstruction with submental island flap except 1 case with radial forearm free flap because of no definite venous drainage. The sizes of the submental island flap varied from 6 cm × 4 cm to 9 cm × 6 cm. Results Operation time ranged from 4 hours and 30 minutes to 7 hours and 10 minutes (mean, 5 hours and 53 minutes) in 14 cases undergoing repair with submental island flap. All the flaps survived completely in 13 cases except 1 case having superficial necrosis of the flap, which was cured after conservative treatment. Temporary marginal mandibular nerve palsy occurred in 1 case, and was cured after 3 months; submandibular effusion was observed in 3 cases, and was cured after expectant treatment. The follow-up period ranged from 8 to 15 months (mean, 10.5 months) in 14 cases undergoing repair with submental island flap. Hair growth was seen on the flap and became sparse after 3 months in 2 male cases. The appearance of the face, opening mouth, swallowing, and speech were recovered well in 14 cases, and the donor site had no obvious scar. The follow-up period was 13 months in 1 case undergoing repair with radical free forearm flap, and the appearance and function were recovered well. No local recurrence was found during follow-up. Conclusion The submental island flap has reliable blood supply, and could be harvested simply and rapidly. It can be used to repair oral defects in patients with early-stage OSCC after radical resection.
ObjectiveTo explore the reliability and effectiveness of soft tissue defect reconstruction using the lower trapezius musculocutaneous flap carrying a portion of the latissimus dorsi muscle.MethodsBetween December 2014 and December 2019, 13 patients underwent the reconstruction of soft tissue defects in various sites using the lower trapezius musculocutaneous flap carrying a portion of the latissimus dorsi muscle. There were 10 males and 3 females, with an average age of 52.1 years (range, 29-83 years). Twelve wounds were resulted from resection of various malignant tumor, including 6 cases of head and neck tumors, 5 cases of shoulder and back tumors, 1 case of chest and back tumors. Among the 12 cases, 4 cases were complicated with wound infection and bone exposure, 1 case with skull defect and cerebral dura exposure, and 1 case with wound infection, skull necrosis, and cerebrospinal fluid leakage. One case was injured in a traffic accident, which resulted in infection wound in the back and shoulder and bone exposure. The sizes of the defect and musculocutaneous flap ranged from 11 cm×7 cm to 23 cm×15 cm and 25 cm×8 cm to 40 cm×14 cm, respectively. According to the spatial relationship between the donor and recipient sites, propeller flaps (8 cases) or percutaneous tunnel island flaps (5 cases) were used to transfer the myocutaneous flap to the recipient area to repair the wound. The donor site was directly closed and sutured in 9 cases, and those with excessive tension were repaired with free skin grafts in 2 cases or transferred flaps in 2 cases.ResultsAfter the operation, necrosis of the distal 4-cm of the musculocutaneous flap occurred in 2 cases. After debridement, the resultant wounds were reconstructed using a local flap and a posterior intercostal artery perforator flap, respectively. The remaining 11 myocutaneous flaps survived completely without arteries and veins crisis. The wounds in the donor and recipient areas healed by first intention. All the patients were followed up 1 to 48 months (mean, 7.4 months). The color and texture of the flap were good. During the follow-up, 1 patient underwent tumor resection again due to tumor recurrence, and 1 patient with a scalp hemangiosarcoma died due to unexplained thoracic hemorrhage. Tumor recurrence was not found in the remaining patients. The musculocutaneous flap coverage was stable and the infection was controlled.ConclusionThe lower trapezius musculocutaneous flap carrying a portion of the latissimus dorsi muscle can be an alternation option to reconstruct refractory wounds with exposure of vital structures and organs and infection.
ObjectiveTo investigate the application of three-dimensional (3-D) printing technique combining with 3-D CT and computer aided-design technique in customized artificial bone fabrication, correcting mandibular asymmetry deformity after mandibular angle ostectomy. MethodsBetween April 2011 and June 2013, 23 female patients with mandibular asymmetry deformity after mandibular angle ostectomy were treated. The mean age was 27 years (range, 22-34 years). The disease duration of mandibular asymmetry deformity was 6-16 months (mean, 12 months). According to the CT data and individualized mandibular angle was simulated based on mirror theory, 3-D printed implants were fabricated as the standard reference for manufacturers to fabricated artificial bone graft, and then mandible repair operation was performed utilizing the customized artificial bone to improve mandibular asymmetry. ResultsThe operation time varied from 40 to 60 minutes (mean, 50 minutes). Primary healing of incisions was obtained in all patients; no infection, hematoma, and difficulty in opening mouth occurred. All 23 patients were followed up 3-10 months (mean, 6.7 months). After operation, all patients obtained satisfactory facial and mandibular symmetry. 3-D CT reconstructive examination results after 3 months of operation showed good integration of the artificial bone. Conclusion3-D printing technique combined with 3-D CT and computer aided design technique can be a viable alternative to the approach of maxillofacial defects repair after mandibular angle ostectomy, which provides a accurate and easy way.
Objective To investigate the effect of simvastatin on inducing endothel ial progenitor cells (EPCs) homing and promoting bone defect repair, and to explore the mechanism of local implanting simvastatin in promoting bone formation. Methods Simvastatin (50 mg) compounded with polylactic acid (PLA, 200 mg) or only PLA (200 mg) was dissolved in acetone (1 mL) to prepare implanted materials (Simvastatin-PLA material, PLA material). EPCs were harvested from bone marrow of 2 male rabbits and cultured with M199; after identified by immunohistochemistry, the cell suspension of EPCs at the 3rd generation (2 × 106 cells/mL) was prepared and transplanted into 12 female rabbits through auricular veins(2 mL). After 3 days, the models of cranial defect with 15 cm diameter were made in the 12 female rabbits. And the defects were repaired with Simvastatin-PLA materials (experimental group, n=6) and PLA materials (control group, n=6), respectively. The bone repair was observed after 8 weeks of operation by gross appearance, X-ray film, and histology; gelatin-ink perfusion and HE staining were used to show the new vessels formation in the defect. Fluorescence in situ hybridization (FISH) was performed to show the EPCs homing at the defect site. Results All experimental animals of 2 groups survived to the end of the experiment. After 8 weeks in experimental group, new bone formation was observed in the bone defect by gross and histology, and an irregular, hyperdense shadow by X-ray film; no similar changes were observed in control group. FISH showed that the male EPC containing Y chromosome was found in the wall of new vessels in the defect of experimental group, while no male EPC containing Y chromosome was found in control group. The percentage of new bone formation in defect area was 91.63% ± 4.07% in experimental group and 59.45% ± 5.43% in control group, showing significant difference (P lt; 0.05). Conclusion Simvastatin can promote bone defect repair, and its mechanism is probably associated with inducing EPCs homing and enhancing vasculogenesis.