BACKGROUND: Scaffolds are an important part in bone tissue engineering. However, no perfect scaffolds have been developed for bone tissue engineering yet.OBJECTIVE: To evaluate the repair of rabbit radial defects by poly (L-lactic acid)/tricalcium phosphate(PLLA/TCP) scaffolds prepared by rapid prototyping(RP) technology so as to find a new carrier for growth factors.DESIGN: A completely randomized controlled study was conducted. SETTING: Orthopaedic institute of a military medical university.MATERIALS: The study was conducted in the General Orthopedic Institute,Fourth Military Medical University of Chinese PLA, from May 2001 to February 2002. Twenty clean New Zealand rabbits with body mass of(2.5 ±0. 5) kg for this study were obtained from the Experiment Animal Center of Fourth Military Medical University of Chinese PLA. The animals were divided into experiment group and control group with 10 rabbits in each group.INTERVETIONS: PLLA/TCP scaffolds prepared by RP technology and loaded with or without bovine bone morphogenetic protein (BMP) were used to repair the rabbit radial defects of 15 mm.MAIN OUTCOME MEASURES: Main outcomes: ① microscopic observation results of transplanted materials of the two groups; ② degradation rate of scaffolds. Secondary outcomes: ① gross observation; ② radiographic results; ③ bone density.RESULTS: At week 12, bone defect healing in experiment group was good. X-ray examination showed continuous bone callus and partial molding of different degrees. Degradation rate of scaffolds was 39.6%, and bone density in the defected part reached 70% of the normal level. All the indexes of experiment group were superior to those of control group, and no healing was found in the defected area in control group.CONCLUSION: PLLA/TCP scaffolds prepared by RP technology and loaded with bovine BMP can repair radial defects of 15mm in rabbits.

Tri-dimensional poly (DL-lactic-co-glycolic acid) (PLGA) scaffolds were fabricated using a rapid prototyping (RP) technique and the gene of human bone morphogenetic protein 2 (hBMP-2) was transferred into rabbit bone marrow stromal cells (MSCs) via recombinant adeno-associated virus vectors (rAAV-hBMP-2). Thirty-two PLGA scaffolds, size (4 mm X 4 mm X 4 mm), were coated with collagen type I and equally divided into 2 groups. In group A, each scaffold was loaded with 2 X 10(4) hBMP-2 (+) MSCs to establish a hBMP-2 (+) MSCs/PLGA composite. In group B, each scaffold was loaded with 2 X 10(4) hBMP-2 (-) MSCs to establish a hBMP-2 (-) MSCs/PLGA composite. The composites in both groups were cultured for subcutaneous implantation in nude mice. All animals were killed 30 days after implantation and the differentiation of composites was evaluated. As a result, MSCs infected with rAAV-hBMP-2 efficiently expressed hBMP-2 protein. RP-based PLGA scaffolds had ideal microarchitecture. The diameters of macropore and micropore of the scaffolds were 300 microm and 3-5 microm, respectively. At 3-5 days after culture, a number of seeding cells well grew on the scaffolds of both groups. The composites in group A had chondrogenesis ability in vivo and the expression of collagen type II was positive. In group B, however, only polymers and fiber tissues were predominantly found. The percentage of polymer remnant area was significantly lower in group A than in group B (P<0.01). Our results therefore indicate that RP-based PLGA scaffolds efficiently coated with collagen type I have good biocompatibility with hBMP-2 (+) MSCs and the techniques developed in this study may favor cartilage tissue engineering.
Animals ; Biocompatible Materials ; Bone Marrow Cells ; cytology ; Bone Morphogenetic Protein 2 ; Bone Morphogenetic Proteins ; genetics ; Cell Differentiation ; Cells, Cultured ; Chondrogenesis ; Guided Tissue Regeneration ; methods ; Humans ; Implants, Experimental ; Lactic Acid ; Male ; Mice ; Mice, Nude ; Polyglycolic Acid ; Polymers ; Rabbits ; Stromal Cells ; cytology ; Tissue Engineering ; methods ; Transfection ; Transforming Growth Factor beta ; genetics

Under laboratory condition, the compound materials of Poly (DL-lactic-co-glycolic acid)/Tricalcium phosphate [PLGA/TCP(L), with component ratio of 7:3] were fabricated by combining the thermally induced phase separation (TIPS) with solvent-casting particulate-leaching (SCPL) approach. On the other hand, rapid prototyping (RP) technique manufactured PLGA/TCP scaffolds [PLGA/TCP(RP)] were obtained. These two kinds of carriers were coated with collagen type I (Col I). The extracted bovine bone morphogenetic protein (bBMP) was loaded into carriers to establish biomimetic synthetic bones. PLGA/TCP(L) scaffolds, demineralized bone matrices (DBM) of bovine cancellous bone, PLGA/TCP(L) scaffolds, biomimetic synthetic bones and OsteoSet bone graft substitutes were investigated. Scanning electron microscopy revealed that the microarchitecture of PLGA/TCP(RP) scaffolds was much better than that of PLGA/TCP(L) scaffolds. The diameter of macropore of PLGA/TCP(RP) scaffold was 350 microm. The porosities of PLGA/ TCP(L) scaffolds, DBM, PLGA/TCP(RP) scaffolds and OsteoSet bone graft substitutes were 21.5%, 70.4%, 58.6% and 0%, respectively (P<0.01). Modification of PLGA/TCP scaffolds with collagen type I [PLGA/TCP(L)-Col I and PLGA/TCP(RP)-Col I] essentially increased the affinity of the carriers to bBMP. Among these synthetic materials, PLGA/TCP(RP)-Col I-bBMP composite is promising as a novel bone graft substitute due to its advanced fabrication technique, good tri-dimensional microarchitecture and ideal components.
Biocompatible Materials ; chemistry ; Bone Morphogenetic Proteins ; chemistry ; Bone Substitutes ; chemistry ; Calcium Phosphates ; chemistry ; Humans ; Lactic Acid ; chemistry ; Microscopy, Electron, Scanning ; Polyglycolic Acid ; chemistry ; Porosity ; Surface Properties ; Tissue Engineering ; methods

Objective To determine the effect of bone mesenchymal stem cells (BMSCs) in transplantation therapy for lipopolysaccharide (LPS)-induced coagulation disorder and the underlying mechanism of high mobility group protein B1-receptors for advanced glycation end products / Toll-like receptors-nuclear factor-κB (HMGB1-RAGE / TLRs-NF-κB) signaling pathway.Methods BMSCs of female Sprague-Dawley (SD) rats ageing 4-5 weeks old were extracted and cultivatedin vitro, and the fourth-passaged BMSCs phenotype was identified by flow cytometry for transplantation in the following experimental study. The rats were randomly divided into normal saline (NS) control group, LPS group, and BMSC group according to the random number table with 15 rats in each group. Coagulation disorders model was reproduced by injection of 1 mg/kg LPS via saphenous vein, and the rats in the NS control group was injected with equal volume NS. Those in the BMSC group were infused BMSC 0.5 mL containing 1×106 cells via tail vein at 2 hours after LPS injection, and the rats in other groups were injected with equal volume NS. Abdominal aorta blood was collected at 1, 3 and 7 days post operation. Coagulation indexes such as platelet count (PLT), platelet volume distribution width (PDW), mean platelet volume (MPV), plateletcrit (PCT), platelet large cell ratio (P-LCR), activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), international normalized ratio (INR), and fibrinogen (FIB) were determined. The mRNA levels and contents of HMGB1, RAGE, TLR2/4 and NF-κB were determined by real-time reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively.Results ① The cells culturedin vitro were spindle shaped or flat. The fourth-passaged BMSCs phenotype was successfully identified by flow cytometry technology. ②Coagulation indexes: compared with NS control group, PLT, PCT and FIB in LPS group were significantly decreased, PDW, MPV, P-LCP, and INR were significantly increased, and APTT, PT, and TT were significantly prolonged from the first day. Furthermore, those in LPS group were gradually ameliorated with prolongation of LPS induction time. The coagulation function abnormality induced by LPS was reversed by BMSCs with significant difference at 1 day as compared with LPS group [PLT (×109/L):398.8±17.9 vs. 239.1±15.8, PCT (％): 0.35±0.04 vs. 0.23±0.06, FIB (g/L): 1.7±0.6 vs. 0.8±0.1, PDW (％):12.4±1.6 vs. 16.2±1.5, MPV (fl): 11.0±1.6 vs. 13.7±1.1, P-LCP (％): 13.0±2.1 vs. 15.3±2.7, INR: 1.52±0.17 vs. 1.82±0.19, APTT (s): 66.3±4.1 vs. 89.5±4.5, PT (s): 18.3±0.7 vs. 25.1±1.9, TT (s): 87.5±7.8 vs. 115.0±9.7, allP < 0.05], till 7 days. ③ HMGB1-RAGE / TLRs-NF-κB signaling pathway related molecules: compared with NS control group, the mRNA expressions and contents of HMGB1, RAGE, TLR2/4 and NF-κB were significantly increased in LPS group from the first day. However, the mRNA expressions and contents of the molecules in LPS group were gradually decreased with prolongation of LPS induction time. After BMSC intervention, the mRNA expressions and contents of molecules at 1 day were significantly lower than those of LPS group [HMGB1 mRNA (2-ΔΔCt): 10.77±0.04 vs. 24.51±3.69, HMGB1 content (μg/L): 0.48±0.01 vs. 0.95±0.06; RAGE mRNA (2-ΔΔCt): 11.57±1.11 vs. 18.08±0.29, RAGE content (μg/L): 0.73±0.04 vs. 1.37±0.06; TLR2 mRNA (2-ΔΔCt): 2.60±0.22 vs. 12.61±0.27, TLR2 content (μg/L): 0.81±0.03 vs. 1.59±0.09; TLR4 mRNA (2-ΔΔCt): 2.95±0.52 vs. 4.06±0.11, TLR4 content (μg/L):0.80±0.09 vs. 1.18±0.11; NF-κB mRNA (2-ΔΔCt): 1.29±0.06 vs. 7.79±0.25, NF-κB content (μg/L): 1.22±0.24 vs. 2.42±0.26, allP < 0.05], till 7 days.Conclusion BMSCs administration could ameliorate the coagulation function in LPS-induced coagulation disorder rats and these might be associated with HMGB1-RAGE / TLRs-NF-κB signaling pathway inhibition.

Osteoporotic vertebral compression fracture (OVCF) is the most common fragility fracture. Along with growth of population and increase of average life expectancy, the incidence of OVCF is rising constantly. As a common complication of OVCF, vertebral refracture not only possesses a high incidence, but also places a heavy physical, mental and financial burden on patients due to the pain and motor dysfunction. How to effectively prevent and treat the vertebral refracture has become a clinical focus at home and abroad. Vertebral refracture is a cumulative result of multiple factors, including patient factors as well as treatment factors. Accordingly, the authors summarize the related risk factors of vertebral refracture in OVCF patients in terms of systemic, local and therapeutic factors, so as to provide a certain reference for reducing the incidence of vertebral refracture and follow-up researches.