Redifferentiation of genetically modified dedifferentiated chondrocytes in a microcavitary hydrogel.

OBJECTIVES: We genetically modified dedifferentiated chondrocytes (DCs) using lentiviral vectors and adenoviral vectors encoding TGF-ß3 (referred to as transgenic groups below) and encapsulated these DCs in the microcavitary hydrogel and investigated the combinational effect on redifferentiation of the genetically manipulated DCs. RESULTS: The Cell Counting Kit-8 data indicated that both transgenic groups exhibited significantly higher cell viability in the first week but inferior cell viability in the subsequent timepoints compared with those of the control group. Real-time polymerase chain reaction and western blot analysis results demonstrated that both transgenic groups had a better effect on redifferentiation to some extent, as evidenced by higher expression levels of chondrogenic genes, suggesting the validity of combination with transgenic DCs and the microcavitary hydrogel on redifferentiation. Although transgenic DCs with adenoviral vectors presented a superior extent of redifferentiation, they also expressed greater levels of the hypertrophic gene type X collagen. It is still worth further exploring how to deliver TGF-ß3 more efficiently and optimizing the appropriate parameters, including concentration and duration. CONCLUSIONS: The results demonstrated the better redifferentiation effect of DCs with the combinational use of transgenic TGF-ß3 and a microcavitary alginate hydrogel and implied that DCs would be alternative seed cells for cartilage tissue engineering due to their easily achieved sufficient cell amounts through multiple passages and great potential to redifferentiate to produce cartilaginous extracellular matrix.

Progress in Osteochondral Regeneration with Engineering Strategies.

Osteoarthritis, the main cause of disability worldwide, involves not only cartilage injury but also subchondral bone injury, which brings challenges to clinical repair. Tissue engineering strategies provide a promising solution to this degenerative disease. Articular cartilage connects to subchondral bone through the osteochondral interfacial tissue, which has a complex anatomical architecture, distinct cell distribution and unique biomechanical properties. Forming a continuous and stable osteochondral interface between cartilage tissue and subchondral bone is challenging. Thus, successful osteochondral regeneration with engineering strategies requires intricately coordinated interplay between cells, materials, biological factors, and physical/chemical factors. This review provides an overview of the anatomical composition, microstructure, and biomechanical properties of the osteochondral interface. Additionally, the latest research on the progress related to osteochondral regeneration is reviewed, especially discussing the fabrication of biomimetic scaffolds and the regulation of biological factors for osteochondral defects.

Preparation of calcium phosphate cement and polymethyl methacrylate for biological composite bone cements.

BACKGROUND: We studied the biological safety, biomechanics, and tissue compatibility of calcium phosphate cement and Polymethyl Methacrylate composite bone cement mixed in different ratios. MATERIAL/METHODS: CPC and PMMA were mixed in different ratios (3:1, 2:1, 1:1, 1:2, 1:5, 1:10, 1:15, and 1:20). PMMA solvent is a general solvent containing a dissolved preparation of the composite bone cement specific to a given specimen to determine biological safety, biomechanics, and tissue compatibility. RESULTS: The CPC/PMMA (33%) group, CPC/PMMA (50%) group, CPC/PMMA (67%) group, and CPC/PMMA (75%) group were more in line with the composite bone cement without cytotoxicity requirements. The compressive strength of the CPC/PMMA (67%) group and CPC/PMMA (75%) group was 20 Mpa-30 Mpa, while that of the CPC/PMMA (4.8%) group, CPC/PMMA (6.25%) group, CPC/PMMA (9.1%) group, CPC/PMMA (16.7%) group, CPC/PMMA (33%) group, and CPC/PMMA (50%) group was 40 Mpa-70 Mpa. Curing time was longer in the CPC group (more than 11 min) and shorter in the PMMA group (less than 2 min). The results of weight loss rate showed that there were no significant differences between the CPC/PMMA group (4.8%, 6.25%, 9.1%, 16.7%, 33%) and PMMA control group (p>0.05). With the decrease of CPC content, the rate of weight loss gradually decreased. CONCLUSIONS: The CPC/PMMA (50%) group, CPC/PMMA (67%) group, and CPC/PMMA (75%) group provide greater variability and selectivity for the composite bone cement in obtaining better application.

Aucubin prevents interleukin-1 beta induced inflammation and cartilage matrix degradation via inhibition of NF-κB signaling pathway in rat articular chondrocytes.

Proinflammatory cytokine interleukin-1ß (IL-1ß) plays a crucial role in the pathogenesis of Osteoarthritis (OA) by stimulating several mediators contributed to cartilage degradation. Aucubin, a natural compound derived from plants which has been shown to possess diverse biological activities including anti-inflammatory property, may benefit the IL-1ß stimulated chondrocytes. The present study was aimed to investigate the effects of Aucubin on IL-1ß stimulated rat chondrocytes. Rat chondrocytes were cultured and pretreated with Aucubin (1, 10, 20, 50µM), and then stimulated with or without IL-1ß (10ng/ml). Gene and protein expression of MMP-3, MMP-9, MMP-13, cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) was determined by real-time PCR and Western blotting respectively. Nitric oxide (NO) production was quantified by Griess reagent. Phosphorylation and nuclear translocation of p65 were detected by western blotting and immunofluorescence, respectively. We found that Aucubin significantly reversed the elevated gene and protein expression of MMP-3, MMP-9, MMP-13, iNOS, COX-2 and the production of NO induced by IL-1ß challenge in rat chondrocytes. Furthermore, Aucubin was able to suppress the IL-1ß-mediated phosphorylation and nuclear translocation of p65, indicating Aucubin may possibly act via the NF-κB signaling pathway. The present study proposes that Aucubin may be a potential therapeutic choice in the treatment of OA due to its anti-inflammatory and chondroprotective features.

Proximal femoral nail vs. dynamic hip screw in treatment of intertrochanteric fractures: a meta-analysis.

BACKGROUND: The aim of this meta-analysis was to compare the outcomes of proximal femoral nail (PFN) and dynamic hip screw (DHS) in treatment of intertrochanteric fractures. MATERIAL AND METHODS: Relevant randomized or quasi-randomized controlled studies comparing the effects of PFN and DHS were searched for following the requirements of the Cochrane Library Handbook. Six eligible studies involving 669 fractures were included. Their methodological quality was assessed and data were extracted independently for meta-analysis. RESULTS: The results showed that the PFN group had significantly less operative time (WMD: -21.15, 95% CI: -34.91 - -7.39, P=0.003), intraoperative blood loss (WMD: -139.81, 95% CI: -210.39 - -69.22, P=0.0001), and length of incision (WMD: -6.97, 95% CI: -9.19 - -4.74, P<0.00001) than the DHS group. No significant differences were found between the 2 groups regarding postoperative infection rate, lag screw cut-out rate, or reoperation rate. CONCLUSIONS: The current evidence indicates that PFN may be a better choice than DHS in the treatment of intertrochanteric fractures.

Effects of celecoxib on proliferation and tenocytic differentiation of tendon-derived stem cells.

NSAIDs are often ingested to reduce the pain and improve regeneration of tendon after tendon injury. Although the effects of NSAIDs in tendon healing have been reported, the data and conclusions are not consistent. Recently, tendon-derived stem cells (TDSCs) have been isolated from tendon tissues and has been suggested involved in tendon repair. Our study aims to determine the effects of COX-2 inhibitor (celecoxib) on the proliferation and tenocytic differentiation of TDSCs. TDSCs were isolated from mice Achilles tendon and exposed to celecoxib. Cell proliferation rate was investigated at various concentrations (0.1, 1, 10 and 100 µg/ml) of celecoxib by using hemocytometer. The mRNA expression of tendon associated transcription factors, tendon associated collagens and tendon associated molecules were determined by reverse transcription-polymerase chain reaction. The protein expression of Collagen I, Collagen III, Scleraxis and Tenomodulin were determined by Western blotting. The results showed that celecoxib has no effects on TDSCs cell proliferation in various concentrations (p>0.05). The levels of most tendon associated transcription factors, tendon associated collagens and tendon associated molecules genes expression were significantly decreased in celecoxib (10 µg/ml) treated group (p<0.05). Collagen I, Collagen III, Scleraxis and Tenomodulin protein expression were also significantly decreased in celecoxib (10 µg/ml) treated group (p<0.05). In conclusion, celecoxib inhibits tenocytic differentiation of tendon-derived stem cells but has no effects on cell proliferation.

[Detection of the mRNA expression of human angiotensin-converting enzyme 2 as a SARS coronavirus functional receptor in human femoral head].

OBJECTIVE: To investigate the mRNA expression of severe acute respiratory syndrome-associated coronavirus (SARS-COV) functional receptor, angiotensin-converting enzyme 2 (ACE2), in human femoral head and conjunctiva, and explore the possible entry route of SARS-COV in human femoral head. METHODS: ACE2 mRNA in human femoral head was detected by nested RT-PCR with human beta actin gene as the positive control. RESULTS: The mRNA of human beta actin gene could be amplified efficiently in all the tissue samples. The mRNA of human ACE2 was expressed efficiently in the normal lung tissue, but not in the cartilage and cancellous bone under the weight-bearing area of the femoral head. CONCLUSION: SARS-COV can not infect the femoral head tissue and lead to avascular necrosis of the femoral head directly by the spike glycoprotein, and mechanism of the virus for causing avascular necrosis needs further investigation.

Deferoxamine prevents cardiac hypertrophy and failure in the gerbil model of iron-induced cardiomyopathy.

To evaluate the effects of the iron chelator deferoxamine on the functional and structural manifestations of iron-induced cardiac dysfunction, we measured cardiac power, left ventricular systolic, and diastolic function as (dP/dt)max and (dP/dt)min, respectively, and left ventricular and septal wall thickness in isolated heart preparations derived from the Mongolian gerbil model of iron overload. We induced iron overload with weekly subcutaneous injections of iron dextran (800 mg/kg/wk); deferoxamine (DFO; 100 mg/kg) was administered twice daily by subcutaneous injection, 5 of 7 days each week; and control animals received weekly subcutaneous injections of dextran alone. Animals administered iron alone initially exhibited, at 5 weeks, increased cardiac power but by 12 to 20 weeks, cardiac power was severely diminished, with impairment of both systolic and diastolic function of the left ventricle and marked cardiac hypertrophy (P<.001 for all vs control animals). Administration of DFO with iron did not interfere with the initial augmentation of cardiac power at 5 weeks but prevented the subsequent deterioration in cardiac performance. After 12 to 20 weeks, gerbils given DFO with iron had mean values of cardiac power indistinguishable from those of control animals; both systolic and diastolic function were significantly enhanced not only in comparison with those of animals treated with iron alone but also with respect to controls. In addition, DFO prevented cardiac hypertrophy; mean ventricular and septal wall thickness in gerbils given DFO and iron were not significantly different from those in controls. In the gerbil model of iron overload, concurrent administration of DFO with iron prevents both the development of cardiac hypertrophy and the progressive deterioration in cardiac performance that are produced by chronic iron accumulation.

Optical mapping reveals conduction slowing and impulse block in iron-overload cardiomyopathy.

Cardiac disease with arrhythmia or heart failure is the leading cause of death in patients with thalassemia major and a major complication of other forms of iron overload. Current antiarrhythmic treatment does not appear to alter the clinical course. Using a gerbil model of iron-overload cardiomyopathy, we previously observed a reduction in the fast inward sodium current in isolated cardiomyocytes. Electrocardiograms (ECGs) in the same gerbil model indicate PR-interval prolongation, QRS-interval widening, and arrhythmias. We hypothesize that such changes in the ECG in this model are the result of abnormal action-potential conduction at the level of the whole heart. To test this hypothesis, we took ECGs and recorded action potentials using high-resolution optical mapping from the anterior surface of 9 iron-overloaded and 9 age-matched control ventricular-paced, Langendorff-perfused gerbil hearts. The iron-overloaded gerbils received weekly iron-dextran injections of 800 mg/kg for 14 to 18 weeks. ECGs showed QRS- and PR-interval prolongation in iron-treated gerbils compared with that in controls. In addition, atrioventricular block was observed in 2 of 6 iron-treated gerbils but not in controls. Conduction velocity was significantly slower in iron-treated gerbils than in controls. At normal pacing rates, abnormal activation patterns caused by stable regions of conduction block were observed in iron-overloaded gerbils (33%) but not in controls. Such abnormal impulse conduction may be a mechanism of increased arrhythmia vulnerability in iron-overload cardiomyopathy.

Deferoxamine promotes survival and prevents electrocardiographic abnormalities in the gerbil model of iron-overload cardiomyopathy.

We investigated the time course of electrocardiographic (ECG) changes in the Mongolian gerbil model of iron overload and the effects of the iron chelator deferoxamine (DFO) on these changes. Iron overload was produced with weekly subcutaneous injections of low doses (200 mg/kg/wk) or high doses (800 mg/kg/wk) of iron-dextran. DFO was administered subcutaneously at a dose of 200 mg/kg/day to high-dose animals. Our results show that (1) survival of iron-overloaded gerbils is dose-dependent, with median survival times of 68 and 14 weeks for low- and high-dose animals, respectively; (2) both low and high doses produce prolongation of the PR interval and bradycardia in early stages and prolongation of the QT interval, premature ventricular contractions, variable degrees of atrioventricular block, changes in the ST segment, and T-wave inversion at later stages coinciding with the development of heart failure; (3) DFO prevented death during 20 weeks of high-dose iron-dextran; (4) DFO prevented ECG changes, although delayed prolongation of PR intervals and QRS complexes occurred; and (5) despite marked prolongation of survival and prevention of ECG changes, DFO had modest effects on total cardiac iron content. We speculate that DFO chelates a small iron pool located within the cytoplasm of iron-overloaded cardiomyocytes.

Bimodal cardiac dysfunction in an animal model of iron overload.

Iron-overload cardiomyopathy is the most common cause of death in patients with thalassemia major, yet the associated changes in cardiac function have not been quantified. We studied the effects of iron overload on cardiac function in Mongolian gerbils, a species that responds to iron overload in the same manner as human beings. We injected iron-dextran or dextran alone at low subcutaneous doses (200 mg/kg/wk) for 20 to 60 weeks and at high doses (800 mg/kg/wk) for 6 to 20 weeks. At shorter durations for either dose, the mean values of cardiac work, coronary flow, left ventricular (dP/dt)(max) and left ventricular (dP/dt)(min) in isolated perfused hearts were significantly greater than control values; at longer durations, these values were significantly less than control values. Echocardiography in intact animals showed eccentric cardiac hypertrophy, increased cardiac output, and normal exercise tolerance at shorter durations of dosage. At longer durations, concentric cardiac hypertrophy developed, and cardiac output and exercise capacity were impaired. The response to iron overload in Mongolian gerbils progresses from an initial state of high cardiac output to a subsequent state of low-output failure similar to the course of cardiomyopathy that has been inferred in patients with transfusional iron overload.