Fate of mesenchymal stem cells transplanted to osteonecrosis of femoral head

The purpose of this study was to investigate the survival and differentiation status of MSCs transplanted to ONFH. Traumatic ONFH was surgically produced in skeletally mature mongrel dogs. Osteonecrosis was treated with either saline (control) or autologous mesenchymal stem cells (MSCs) transplantation after decompression. Green fluorescent protein (GFP) was used to track the transplanted MSCs, the differentiation of MSCs were evaluated by fluorescent double-labeling with GFP between osteocalcin or von Willebrand factor (vWF) at 2nd, 8th, and 12th week after the transplantation. It was demonstrated that GFP-positive cells were present in the necrotic area up to 12 weeks after the transplantation, their number increased from 15% at 2nd week to 38% at 12th week (p < 0.05). Neither osteocalcin nor vWF was detected by immunocytochemistry in GFP-labeled MSCs in vitro, but osteocalcin was immunohistochemically positive in 90% of the GFP-labeled MSCs in vivo, while vWF was still negative. The vWF expression was of no significant difference between the control group and MSCs-transplanted group. The percentages of trabeculae bone volume were 9.36% and 8.42% at 2nd week (p > 0.05), 22.82% and 14.72% at 8th week, and 31.08% and 20.66% at 12th week (p < 0.05) in MSCs-transplanted group and control group, respectively; new trabeculae bone in MSCs-transplanted group was significantly increased as compared to that of control group at 8th and 12th week. The results demonstrated that the transplanted MSCs could survive, proliferate, and differentiate into osteoblasts directly, which contributed to the accelerated repair process. The possible mechanism is site-dependant differentiation.

Iron overload-induced ferroptosis of osteoblasts inhibits osteogenesis and promotes osteoporosis: An in vitro and in vivo study

Growing evidence indicates that iron overload is an independent risk factor for osteoporosis. However, the mechanisms are not fully understood. The purpose of our study was to determine whether iron overload could lead to ferroptosis in osteoblasts and to explore whether ferroptosis of osteoblasts is involved in iron overload-induced osteoporosis in vitro and in vivo. Ferric ammonium citrate was used to mimic iron overload conditions, while deferoxamine and ferrostatin-1 were used to inhibit ferroptosis of MC3T3-E1 cells in vitro. The ferroptosis, osteogenic differentiation and mineralization of MC3T3-E1 cells were assessed in vitro. A mouse iron overload model was established using iron dextran. Immunohistochemical analysis was performed to determine ferroptosis of osteoblasts in vivo. Enzyme-linked immunosorbent assays and calcein-alizarin red S labelling were used to assess new bone formation. Dual x-ray absorptiometry, micro-computed tomography and histopathological analysis were conducted to evaluate osteoporosis. The results showed that iron overload reduced cell viability, superoxide dismutase and glutathione levels, increased reactive oxygen species generation, lipid peroxidation, malondialdehyde levels and ferroptosis-related protein expression, and induced ultrastructural changes in mitochondria. Iron overload could also inhibit osteogenic differentiation and mineralization in vitro. Inhibiting ferroptosis reversed the changes described above. Iron overload inhibited osteogenesis, promoted the ferroptosis of osteoblasts and induced osteoporosis in vivo, which could also be improved by deferoxamine and ferrostatin-1. These results demonstrate that ferroptosis of osteoblasts plays a crucial role in iron overload-induced osteoporosis. Maintaining iron homeostasis and targeting ferroptosis of osteoblasts might be potential measures of treating or preventing iron overload-induced osteoporosis.

Free Vascularized Fibular Grafting Improves Vascularity Compared With Core Decompression in Femoral Head Osteonecrosis: A Randomized Clinical Trial

BACKGROUND

Management of osteonecrosis of the femoral head remains challenging. Core decompression and free vascularized fibular grafting are commonly used surgical procedures for treatment of osteonecrosis of the femoral head. Few studies, however, have compared these two procedures in a randomized controlled study, in terms of improved vascularity of the femoral head, progression of disease, or hip scores. QUESTION/PURPOSES: (1) What is the effect of core decompression and fibular grafting on vascularity of the femoral head as measured by single-photon emission CT (SPECT)/CT? (2) Does one of these two methods lead to greater progression of Association Research Circulation Osseous (ARCO) stage as determined by serial MRI? (3) What is the relationship between the change in vascularity of the femoral head and hip function as measured by the Harris hip score (HHS) and progression to THA as an endpoint?

METHODS

A randomized controlled trial was performed between June 2010 and October 2012 at Zhongshan Hospital, Fudan University. During the study period, 51 patients who presented with ARCO Stages I to IIIB bilateral osteonecrosis were potentially eligible for inclusion, and 33 patients were identified as meeting the inclusion criteria and offered enrollment and randomization. Six patients declined to participate at the time of randomization, leaving a final sample of 27 participants (54 hips). Bilateral hips of each patient were randomly assigned to surgical options: one side was treated with core decompression and the contralateral side was concurrently treated with fibular grafting. SPECT/CT examinations were performed to quantify radionuclide uptake to evaluate vascularity of the femoral head before treatment and at 6 and 36 months after surgery. With the numbers available, we found no differences between the groups regarding vascularity at baseline (64% ± 8% core decompression-treated hips versus 64% ± 7% in the fibular-grafted hips; 95% CI, -5% to 5%; p = 0.90). MR images of the hips were obtained before surgery and at 6, 12, 24, and 36 months postoperatively and staged based on the ARCO classification. All patients were assessed clinically before treatment and followed up at 6, 12, 18, 24, 30, and 36 months after treatment using the HHS. We considered a difference in the HHS of 10 as the minimal clinically important difference (MCID). Patient progression to THA was defined as the endpoint for followup. Six patients (22%) were lost to followup.

RESULTS

By SPECT/CT analysis, decompression-treated hips had lower vascularity than fibular-grafted hips at 6 months (68 % ± 6% versus 95% ± 5%; mean difference, -27%; 95% CI, -32% to -23%; p < 0.001) and 36 months (57% ± 4% versus 91% ± 3%; mean difference, -34%; 95% CI, -37% to -32%; p < 0.001). MRI analysis showed no differences between decompression-treated hips and fibular-grafted hips regarding ARCO stage at 12 months (p = 0.306) and 24 months (p = 0.06). Progression of ARCO staging was more severe in the decompression group than the fibular grafting group at 36 months (p = 0.027). The mean HHS was lower in the decompression group than in the fibular grafting group throughout the followup period, although these differences were at or below the MCID of 10 points early on. However, by 18 months, the scores favored fibular grafting (72 ± 4 versus 84 ± 4; mean difference, -13; 95% CI, -15 to -7; p < 0.001), a finding that was maintained at 24, 30, and 36 months. We found no differences between decompression-treated hips and fibular-grafted hips regarding progression to THA at 36 months (two of 21; p = 0.893).

CONCLUSIONS

Hips that underwent a vascularized fibular grafting procedure fared better than hips receiving core decompression as measured by improved vascularity and less progression of osteonecrosis as measured by ARCO staging. The mean HHS of the fibular-grafted hips was better than that of the decompression-treated hips during the entire postoperative period, but the differences were modest early on, and for the early postoperative period the differences were unlikely to have been clinically important; by 18 months after surgery, the differences probably were clinically important. The mid-term outcomes associated with vascularized fibular grafting seen in our patients are associated with improvements in femoral head vascularity and the potential for bone revitalization.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Intra-articular injection of kartogenin-conjugated polyurethane nanoparticles attenuates the progression of osteoarthritis

Osteoarthritis (OA) is the most common form of joint disease and a leading cause of physical disability, there is an urgent need to attenuate the progression of OA. Intra-articular (IA) injection is an effective treatment for joints diseases, however, the therapeutic effects mostly depend on the efficacy of drug duration in joints. Drug delivery system can provide drug-controlled release and reduce the number of IA injection. In this study, amphiphilic polyurethanes with pendant amino group were synthesized and amide bonds were formed between the amine group of polyurethane and the carboxyl group of kartogenin (KGN), a small molecular reported to show both regenerative and protective effects on cartilage. Our results showed that KGN-conjugated polyurethane nanoparticles (PN-KGN) were spherical and regular in shape with an average size of 25 nm and could sustained and controlled release of KGN in vitro. PN-KGN showed no cytotoxicity and pro-inflammatory effects on chondrocytes. The therapeutic effects in OA model showed that IA injection of KGN could attenuate the progress of OA, however, the cartilage degeneration became obviously at 12 weeks with matrix loss and vertical fissures. By contrast, IA injection of PN-KGN showed less cartilage degeneration with significant lower OARSI scores even at 12 weeks, indicating PN-KGN could further arrest the development of OA. Immunohistochemistry also validated that IA injection of PN-KGN retained the normal compositions of cartilage matrix, with much stronger Col II staining and less Col I staining. In conclusion, IA injection of PN-KGN is a better potential strategy to treat OA, with long-time cartilage protection and less IA injections.

Biodegradable composite scaffolds of bioactive glass/chitosan/carboxymethyl cellulose for hemostatic and bone regeneration

Hemostasis in orthopedic osteotomy or bone cutting requires different methods and materials. The bleeding of bone marrow can be mostly stopped by bone wax. However, the wax cannot be absorbed, which leads to artificial prosthesis loosening, foreign matter reaction, and infection. Here, a bioactive glass/chitosan/carboxymethyl cellulose (BG/CS/CMC) composite scaffold was designed to replace traditional wax. WST-1 assay indicated the BG/CS/CMC composite resulted in excellent biocompatibility with no cytotoxicity. In vivo osteogenesis assessment revealed that the BG/CS/CMC composite played a dominant role in bone regeneration and hemostasis. The BG/CS/CMC composite had the same hemostasis effect as bone wax; in addition its biodegradation also led to the functional reconstruction of bone defects. Thus, BG/CS/CMC scaffolds can serve as a potential material for bone repair and hemostasis in critical-sized bone defects.

Injectable double-crosslinked hydrogels with kartogenin-conjugated polyurethane nano-particles and transforming growth factor β3 for in-situ cartilage regeneration

Articular cartilage has a limited ability for self-repair after injury. Implantation of scaffolds functionalized with bioactive molecules that could induce the migration and chondrogenesis of endogenous mesenchymal stem cells (MSCs) provides a convenient alternative for in-situ cartilage regeneration. In this study, we found the synergistic effects of kartogenin (KGN) and transforming growth factor β3 (TGF-β3) on chondrogenesis of MSCs in vitro, indicating that KGN and TGF-β3 are a good match for cartilage regeneration. Furthermore, we confirmed that KGN promoted the chondrogenesis of MSCs through attenuating the degradation of Runx1, which physically interacted with p-Smad3 in nuclei of MSCs. Meanwhile, we designed an injectable double-crosslinked hydrogel with superior mechanical property and longer support for cartilage regeneration by modifying sodium alginate and gelatin. When loaded with KGN conjugated polyurethane nanoparticles (PN-KGN) and TGF-β3, this hydrogel showed biological functions by the release of KGN and TGF-β3, which promoted the MSC migration and cartilage regeneration in one system. In conclusion, the cell-free hydrogel, along with PN-KGN and TGF-β3, provides a promising strategy for cartilage repair by attracting endogenous MSCs and inducing chondrogenesis of recruited cells in a single-step procedure.

Clock mutant promotes osteoarthritis by inhibiting the acetylation of NFκB

OBJECTIVES

To examine the effect of the circadian gene Clock on posttranscriptional function and pro-inflammatory mechanisms in osteoarthritis (OA).

METHODS

The cartilage from Clock mutant mice was assessed using histology, (OA) score, and real-time polymerase chain reaction (PCR) quantification of key pro-inflammatory genes. Nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) translocation, posttranslational state and expression levels during day and night conditions were assessed using immunoblot and IP. The regulation of transcription by Clock in cartilage tissue was assessed by using chromatin immunoprecipitation (ChIP) and luciferase assays. Total acetylation level and pattern over 24 h were quantified using immunoblot and real-time PCR. Finally, the effects of exogenous Clock nanoparticle treatment were quantified by histology and immunoblot.

RESULTS

The Clock mutation significantly promoted the degradation of cartilage and the expression of the key pro-inflammatory mediators, IL-1β, IL-6 and MCP-1. The Clock mutation significantly promoted NFκB nuclear translocation. The circadian protein CLOCK positively regulates NFκB at the transcriptional level by binding the E-box domain. The Clock mutation significantly inhibited the total lysine acetylation level in cartilage and inhibited NFκB acetylation at the Lys310 residue but promoted phosphorylation at the Ser276 residue. The forced expression of Clock in vivo inhibited NFκB activation by increasing acetylation and decreasing phosphorylation levels and by decreasing cartilage damage and inflammation.

CONCLUSIONS

This study demonstrates the mutation of Clock promotes inflammatory activity by mediating the posttranscriptional regulation of NFκB in OA pathogenesis.

Treatment of osteonecrosis of the femoral head with VEGF165 transgenic bone marrow mesenchymal stem cells in mongrel dogs

We evaluated the efficacy of vascular endothelial growth factor 165 (VEGF(165)) transgenic bone marrow mesenchymal stem cells (BMSCs) for the repair of early-stage osteonecrosis of the femoral head (ONFH) in mature mongrel dogs. This animal model was surgically established by femoral neck osteotomy and subsequent repinning. Twenty-seven dogs (54 hips) were divided into 3 equal-sized groups: a pCI-neo-VEGF(165) BMSC group, a pCI-neo BMSC group and a core decompression-alone group. The lipofectamine was used to introduce the VEGF(165) gene into the BMSCs. After core decompression, transgenic and non-transgenic autologous BMSCs were implanted. Therapeutic efficacy, including new bone formation and neovascularization in the femoral head, was examined by computed radiography, single-photon emission computed tomography, histological and histomorphometric analysis and immunofluorescent staining for von Willebrand factor in pathological sections. The femoral osteotomy site healed completely by the 4th week after the osteotomy surgery and regions of histologically evident osteonecrosis were found 12 weeks later. A regular arrangement of trabeculae and obvious bone regeneration were observed in the animals receiving implanted VEGF-transgenic BMSCs. The quantity of newly generated capillaries was significantly increased in the pCI-neo-VEGF(165) BMSC group, but there was no significant difference between the pCI-neo BMSC group and the core decompression-alone group. These results demonstrated that VEGF(165) transgenic autologous BMSCs enhanced bone reconstruction and blood vessel regeneration in the ONFH model. Compared with non-transgenic BMSCs, this approach could provide advanced benefits in the treatment of ONFH.

The Circadian Gene Clock Regulates Bone Formation Via PDIA3

The expression patterns of clock-controlled genes (ccgs) are regulated by circadian rhythm, which is a major regulatory and physiological mechanism tied to the solar day. Disruptions in circadian rhythm contribute to the development of cardiovascular diseases, cancer, metabolic syndromes, and aging. It has been reported that bone remodeling is also regulated by circadian rhythm. However, the molecular mechanism by which the circadian gene Clock regulates bone remodeling has yet to be elucidated. Here, we show that Clock mutant mice exhibit a significant reduction in bone density as well as increased apoptosis. Protein disulfide isomerase family A member 3 (PDIA3) is a 1,25-dihydroxy-vitamin D3 [1α,25(OH)2D3] receptor that can regulate bone formation and apoptosis. Using luciferase and ChIP assays, we confirmed that Pdia3 is a ccg. Clock activates Pdia3 transcription by binding the E-box promoter, and transcription is decreased in ClockΔ19 mutant mice. Forced expression of Pdia3 or of Clock completely rescues the osteogenic disorders found in the mutant background and inhibits apoptosis in vivo and in vitro. Furthermore, ablation of PDIA3 via RNA interference completely blocks the compensatory effect of forced expression of Clock in osteoblasts. Our results demonstrate that the core circadian gene Clock regulates bone formation via transcriptional control of 1,2,5(OH)2D3 receptor PDIA3. © 2016 American Society for Bone and Mineral Research.

A prospect of cell immortalization combined with matrix microenvironmental optimization strategy for tissue engineering and regeneration

Cellular senescence is a major hurdle for primary cell-based tissue engineering and regenerative medicine. Telomere erosion, oxidative stress, the expression of oncogenes and the loss of tumor suppressor genes all may account for the cellular senescence process with the involvement of various signaling pathways. To establish immortalized cell lines for research and clinical use, strategies have been applied including internal genomic or external matrix microenvironment modification. Considering the potential risks of malignant transformation and tumorigenesis of genetic manipulation, environmental modification methods, especially the decellularized cell-deposited extracellular matrix (dECM)-based preconditioning strategy, appear to be promising for tissue engineering-aimed cell immortalization. Due to few review articles focusing on this topic, this review provides a summary of cell senescence and immortalization and discusses advantages and limitations of tissue engineering and regeneration with the use of immortalized cells as well as a potential rejuvenation strategy through combination with the dECM approach.

CD105 promotes chondrogenesis of synovium-derived mesenchymal stem cells through Smad2 signaling

Mesenchymal stem cells (MSCs) are considered to be suitable for cell-based tissue regeneration. Expressions of different cell surface markers confer distinct differentiation potential to different sub-populations of MSCs. Understanding the effect of cell surface markers on MSC differentiation is essential to their targeted application in different tissues. Although CD105 positive MSCs possess strong chondrogenic capacity, the underlying mechanisms are not clear. In this study, we observed a considerable heterogeneity with respect to CD105 expression among MSCs isolated from synovium. The CD105(+) and CD105(-) synovium-derived MSCs (SMSCs) were sorted to compare their differentiation capacities and relative gene expressions. CD105(+) subpopulation had higher gene expressions of AGG, COL II and Sox9, and showed a stronger affinity for Alcian blue and immunofluorescent staining for aggrecan and collagenase II, as compared to those in CD105(-) cells. However, no significant difference was observed with respect to gene expressions of ALP, Runx2, LPL and PPARγ. CD105(+) SMSCs showed increased levels of Smad2 phosphorylation, while total Smad2 levels were similar between the two groups. There was no difference in activation of Smad1/5. These results were further confirmed by CD105-knockdown in SMSCs. Our findings suggest a stronger chondrogenic potential of CD105(+) SMSCs in comparison to that of CD105(-) SMSCs and that CD105 enhances chondrogenesis of SMSCs by regulating TGF-β/Smad2 signaling pathway, but not Smad1/5. Our study provides a better understanding of CD105 with respect to chondrogenic differentiation.

Fabrication of modified dextran-gelatin in situ forming hydrogel and application in cartilage tissue engineering

Hydrogels play a very important role in cartilage tissue engineering. Here, we oxidized dextran (Odex) and modified gelatin (Mgel) to fabricate a fast forming hydrogel without the addition of a chemical crosslinking agent. The dynamic gelling process was measured through rheological measurements. The microstructure was examined by lyophilizing to get porous scaffolds. Biological assessment was performed through CCK-8 assays by using synovium-derived mesenchymal cells (SMSCs) at 1, 3, 7 and 14 days. In vivo evaluation for application in cartilage tissue engineering was performed 8 weeks after subcutaneous injection of SMSC-loaded Odex/Mgel hydrogels combined with TGF-β3 in the dorsa of nude mice. According to the results, a fast forming hydrogel was obtained by simply modifying dextran and gelatin. Moreover, the Odex/Mgel hydrogel exhibited good biocompatibility in cultures of SMSCs and a homogeneous distribution of live cells was achieved inside the hydrogels. After 8 weeks, newly formed cartilage was achieved in the dorsa of nude mice; no inflammatory reaction was observed and high production of GAGs was shown. The method provides a strategy for the design and fabrication of fast in situ forming hydrogels. The Odex/Mgel hydrogel could be used for the regeneration of cartilage in tissue engineering.

Degradation and osteogenic induction of a SrHPO4-coated Mg-Nd-Zn-Zr alloy intramedullary nail in a rat femoral shaft fracture model

Magnesium and Mg-based alloys are promising biomaterials for orthopedic implants because of their degradability, osteogenic effects, and biocompatibility. However, the drawbacks of these materials include high hydrogen gas production, unexpected corrosion resistance, and insufficient mechanical strength duration. Surface modification can protect these biomaterials and induce osteogenesis. In this work, a SrHPO4 coating was developed for our patented biodegradable Mg-Nd-Zn-Zr alloy (abbr. JDBM) through a chemical deposition method. The coating was characterized by in vitro immersion, ion release, and cytotoxicity tests, which showed a slower corrosion behavior and excellent cell viability. RNA sequencing of MC3T3E1 cells treated with SrHPO4-coated JDBM ion release test extract showed increased Tlr4, followed by the activation of the downstream PI3K/Akt signaling pathway, causing proliferation and growth of pre-osteoblasts. An intramedullary nail (IMN) was implanted in a femoral fracture rat model. Mechanical test, radiological and histological analysis suggested that SrHPO4-coated JDBM has superior mechanical properties, induces more bone formation, and decreases the degradation rate compared with uncoated JDBM and the administration of TLR4 inhibitor attenuated the new bone formation for fracture healing. SrHPO4 is a promising coating for JDBM implants, particularly for long-bone fractures.

Lessons from immuno-oncology: a new era for cancer nanomedicine?

Despite a decade of intensive preclinical research, the translation of cancer nanomedicine to the clinic has been slow. Here, we discuss how recent lessons learned from the successes with immuno-oncology therapies could be applied to cancer nanomedicine and how this may help to overcome some of the key technical challenges in this field.

The use of bisphosphonate in the treatment of osteonecrosis of the femoral head: a meta-analysis of randomized control trials

This meta-analysis revealed that bisphosphonates could not provide a better clinical outcome in the treatment of osteonecrosis of the femoral head (ONFH) when compared with placebo.

INTRODUCTION

Bisphosphonates have been recommended to treat ONFH. However, the exact clinical outcomes after treatment are still controversial.

METHODS

A comprehensive search of PubMed, Embase, and Web of Science databases was undertaken, and only randomized control trials were included. The clinical outcomes consisted of progression to collapse, total hip arthroplasty (THA) incidence, and improvement of Harris hip score (HHS). The heterogeneities between the trials were assessed with the I (2) statistic, and random effects models were used for the meta-analysis.

RESULTS

Five eligible trials were identified involving 329 subjects with 920.9 patient-years of follow-up. The clinical outcomes of patients with ONFH was not significantly improved by bisphosphonate therapy (progression to collapse: risk ratio = 0.71 (0.41, 1.24), p = 0.23; THA incidence: risk ratio = 0.61 (0.33, 1.15), p = 0.13; HHS improvement: mean difference = 3.26 (-5.12, 11.64), p = 0.45). The I (2) statistic showed the existence of considerable heterogeneity (all I (2) ≥ 50 %), which was explained by one trial where bisphosphonate alone was used with no additional therapy. However, when this trial was excluded, the clinical outcomes after bisphosphonate therapy were still not significantly improved compared with placebo.

CONCLUSIONS

The current analysis does not support the use of bisphosphonates for ONFH. As potential serious adverse effects are associated with these drugs, only limited use can be recommended.

Involvement of MicroRNA-210 Demethylation in Steroid-associated Osteonecrosis of the Femoral Head

Angiogenesis is an important event in steroid-associated osteonecrosis of the femoral head (SONFH). Here we performed miRNA microarray with SONFH tissues (ONs) and the adjacent normal tissues (NLs) to select the angiogenic miRNA. The results showed that miR-210 was differentially expressed in SONFH versus normal tissues. Unexpectedly, its specific transcription factor, hypoxia-inducible factor-1α, was shown of no significant changes in ONs compared with NLs. Further Bisulfite sequencing revealed that miR-210 is embedded in a CpG island and miR-210 gene has 2 CpG sites with lower methylation percentage in ONs compared with NLs. Additionally, ONs with lower miR-210 gene methylation exhibited higher miR-210 expression. Next, we found that the endothelial cells treated with demethylating agents could significantly increase the expression of miR-210, along with promoted cell viability and differentiation. Some angiogenic genes (VEGF, bFGF, TNF-α and PCNA) were up-regulated as well. In addition, the supernatant of the cells after demethylation treatment displayed an enhanced ability of recruiting new microvessels in vivo. Taken together, our study not only provides novel insights into the regulation of angiogenesis in this disease, but also reveals a therapeutic opportunity for treatment of SONFH patients with demethylating agents.

Engeletin Protects Against TNF-α-Induced Apoptosis and Reactive Oxygen Species Generation in Chondrocytes and Alleviates Osteoarthritis in vivo

PURPOSE

Osteoarthritis (OA) is a progressive disease characterized by pain and impaired joint functions. Engeletin is a natural compound with anti-inflammatory and antioxidant effects on other diseases, but the effect of engeletin on OA has not been evaluated. This study aimed to elucidate the protective effect of engeletin on cartilage and the underlying mechanisms.

METHODS

Chondrocytes were isolated from rat knee cartilage, and TNF-α was used to simulate OA in vitro. After treatment with engeletin, the expression of extracellular matrix (ECM) components (collagen II and aggrecan) and matrix catabolic enzymes (MMP9 and MMP3) was determined by Western blotting and qPCR. Chondrocyte apoptosis was evaluated using Annexin V-FITC/PI and flow cytometry. Apoptosis-related proteins (Bax, Bcl-2, and cleaved caspase-3) were evaluated by Western blotting. The mitochondrial membrane potential of chondrocytes was measured with JC-1, and intracellular reactive oxygen species (ROS) levels were determined with DCFH-DA. Changes in signaling pathways (Nrf2, NF-κB and MAPK) were evaluated by Western blotting. In vivo, anterior cruciate ligament transection (ACLT) was used to induce the rat OA model, and engeletin was administered intraarticularly. The therapeutic effect of engeletin was analyzed by histopathological analysis.

RESULTS

Pretreatment with engeletin alleviated TNF-α-induced inhibition of ECM components (collagen II and aggrecan) and upregulation of matrix catabolic enzymes (MMP9 and MMP3). Engeletin ameliorated chondrocyte apoptosis by inhibiting Bax expression and upregulating Bcl-2 expression. Engeletin maintained the mitochondrial membrane potential of chondrocytes and scavenged intracellular ROS by activating the Nrf2 pathway. The NF-κB and MAPK pathways were inhibited by treatment with engeletin. In vivo, ACLT-induced knee OA in rats was alleviated by intraarticular injection of engeletin.

CONCLUSION

Engeletin ameliorated OA in vitro and in vivo. It may be a potential therapeutic drug for OA.

Pinocembrin alleviates glucocorticoid-induced apoptosis by activating autophagy via suppressing the PI3K/Akt/mTOR pathway in osteocytes

Glucocorticoids are widely used in clinical practice, but are associated with potentially severe side effects like glucocorticoid-induced osteoporosis (GIOP) and glucocorticoid-associated osteonecrosis of the femoral head (GA-ONFH). Glucocorticoid-induced osteocyte apoptosis plays critical roles in the pathological processes of both GIOP and GA-ONFH. Pinocembrin is a natural flavonoid that may exert protective effects on osteocytes. The present study investigated the effects of pinocembrin on glucocorticoid-induced apoptosis of murine long bone osteocyte Y4 (MLO-Y4) cells and sought to elucidate the underlying molecular mechanism. We found that pinocembrin attenuated glucocorticoid-induced cell viability injury and apoptosis of MLO-Y4 cells. Moreover, pinocembrin increased Beclin-1 and LC3B-II level, but decreased p62 expression, suggesting that pinocembrin activates autophagy in glucocorticoid-treated MLO-Y4 cells. The protective effects of pinocembrin on glucocorticoid-induced apoptosis of MLO-Y4 cells were mimicked by a known stimulator of autophagy but prevented by a known inhibitor of autophagy. Pinocembrin also suppressed the PI3K/Akt/mTOR signaling pathway, which regulates cell autophagy, in glucocorticoid-treated MLO-Y4 cells. In conclusion, the results indicate that pinocembrin alleviates glucocorticoid-induced osteocyte apoptosis by activating autophagy via suppressing the PI3K/Akt/mTOR pathway. Pinocembrin may represent a potential natural agent for preventing and treating GIOP and GA-ONFH.

Clock mediates liver senescence by controlling ER stress

Accumulated evidence indicates that circadian genes regulate cell damage and senescence in most mammals. Endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) regulate longevity in many organisms. However, the specific mechanisms of the relationship between the circadian clock and the two stress processes in organisms are poorly understood. Here, we show that Clock-mediated Pdia3 expression is required to sustain reactive oxidative reagents and ER stress. First, ER stress and ROS are strongly activated in the liver tissue of Clock∆19 mutant mice, which exhibit a significant aging phenotype. Next, transcription of Pdia3 is mediated by the circadian gene Clock, but this process is affected by the Clock∆19 mutant due to the low affinity of the E-box motif in the promoter. Finally, ablation of Pdia3 with siRNA causes ER stress with sustained phosphorylation of PERK and eIF1α, resulting in exaggerated up-regulation of UPR target genes and increased apoptosis as well as ROS. Moreover, the combined effects result in an imbalance of cell homeostasis and ultimately lead to cell damage and senescence. Taken together, this study identified the circadian gene Clock as a regulator of ER stress and senescence, which will provide a reference for the clinical prevention of aging.

Analysis of altered microRNA expression profile in the reparative interface of the femoral head with osteonecrosis

The reparative reaction is considered to be important during the occurrence of collapse in the femoral head with osteonecrosis (ONFH), but little is known about the long-term reparative process. The aim of this study was to determine and analyze the altered microRNA expression profile in the reparative interface of ONFH, and further validate the expression of the involved genes in the predicted pathways. Microarray analysis was performed comparing the reparative interface of patients with ONFH and normal tissue of patients with fresh femoral neck fracture (FNF) and partly validated by real-time PCR. Potential target genes of differentially expressed miRNAs were predicted by TargetScan and miRanda, and the target genes were used for further bioinformatics analysis such as Gene Ontology and Pathway assay. The filtered miRNAs and genes in the predict pathways were further examined by real-time PCR in another 6 independent ONFH patients. Among the 2578 miRNAs identified, 17 were consistently differentially expressed, 12 of which are up-regulated and 5 down-regulated. GO classification showed that the predicted target genes of these miRNAs are involved in signal transduction, cell differentiation, methylation, cell growth and apoptosis. The Kyoto Encyclopedia of Genes and Genomes (KEGG) classification indicated that these genes play a role in angiogenesis and Wnt signaling pathways. The expression of miR-34a and miR-146a and genes in the predict pathways were significantly up-regulated. This study presented a global view of miRNA expression in the reparative interface of osteonecrosis. In addition, our data provided novel and robust information for further researches in the pathogenesis and molecular events of ONFH.

Ankle arthrodesis using anatomically contoured anterior plate

BACKGROUND

More than 40 fusion techniques for the ankle joint have been reported. The purpose of this retrospective study was to review our preliminary clinical and radiographic results using an anatomically contoured anterior plate for ankle arthrodesis.

MATERIALS AND METHODS

Ten ankle arthrodeses with an anatomically contoured anterior plate performed by a single surgeon were reviewed with an average of 14 months followup. One underwent revision surgery due to screw loosening by reapplying the same plate. Plain radiographs were taken to help determine the stability of fixation and time of fusion. The AOFAS clinical rating system was applied to evaluate patients preoperatively and postoperatively.

RESULTS

Nine of ten patients achieved solid fusion radiographically and clinically at an average of 15 (range, 12 to 22) weeks. Bony healing was achieved after an additional 12 weeks for the patient who underwent revision fusion. There were no postoperative wound problems or infections. All patients reported an improvement in their pain level following successful fusion.

CONCLUSION

The application of an anatomically contoured plate provides many advantages, including less soft tissue disruption by using a single anterior incision, ease of deformity correction, early rehabilitation, and high rate of union.

Effects of p-glycoprotein on steroid-induced osteonecrosis of the femoral head

P-glycoprotein (P-gp) activity may play an important role in steroid-induced osteonecrosis of the femoral head (ONF); however, the precise mechanism of its pathogenesis remains unknown. Therefore, we investigated the effects of increased P-gp activity on steroid-induced ONF using a rat model. Rats (n = 60) were treated with either a pharmacological stimulant of P-gp, rifampicin (group A); a suppressant, verapamil (group B); or normal saline (group C) administered in conjunction with methylprednisolone, an inducer of ONF. P-gp activity in bone marrow cells and expression in the femoral head significantly increased in group A (P < 0.05) but decreased in group B (P < 0.05). Likewise, the serum osteocalcin level, trabecular thickness and number, osteoclast and osteoblast numbers, and mean percentage of the epiphyseal ossification center were significantly increased in group A (P < 0.01) but decreased in group B (P < 0.01). In contrast, however, adipocytic variables, trabecular separation, and apoptotic cells decreased in group A (P < 0.01) but increased in group B (P < 0.01). The ONF incidence in group A (50%) and group B (100%) was significantly different from that in the control group C (80%, P < 0.05). Taken together, our findings suggested that enhanced P-gp activity was able to decrease the risk of steroid-induced ONF, possibly by inhibiting adipogenesis and apoptosis in the femoral head.

Role of circadian gene Clock during differentiation of mouse pluripotent stem cells

Biological rhythms controlled by the circadian clock are absent in embryonic stem cells (ESCs). However, they start to develop during the differentiation of pluripotent ESCs to downstream cells. Conversely, biological rhythms in adult somatic cells disappear when they are reprogrammed into induced pluripotent stem cells (iPSCs). These studies indicated that the development of biological rhythms in ESCs might be closely associated with the maintenance and differentiation of ESCs. The core circadian gene Clock is essential for regulation of biological rhythms. Its role in the development of biological rhythms of ESCs is totally unknown. Here, we used CRISPR/CAS9-mediated genetic editing techniques, to completely knock out the Clock expression in mouse ESCs. By AP, teratoma formation, quantitative real-time PCR and Immunofluorescent staining, we did not find any difference between Clock knockout mESCs and wild type mESCs in morphology and pluripotent capability under the pluripotent state. In brief, these data indicated Clock did not influence the maintaining of pluripotent state. However, they exhibited decreased proliferation and increased apoptosis. Furthermore, the biological rhythms failed to develop in Clock knockout mESCs after spontaneous differentiation, which indicated that there was no compensational factor in most peripheral tissues as described in mice models before (DeBruyne et al., 2007b). After spontaneous differentiation, loss of CLOCK protein due to Clock gene silencing induced spontaneous differentiation of mESCs, indicating an exit from the pluripotent state, or its differentiating ability. Our findings indicate that the core circadian gene Clock may be essential during normal mESCs differentiation by regulating mESCs proliferation, apoptosis and activity.

Clinical outcomes of osteonecrosis of the femoral head after autologous bone marrow stem cell implantation: a meta-analysis of seven case-control studies

The purpose of this study was to evaluate the clinical outcomes of osteonecrosis of the femoral head after autologous bone marrow stem cell implantation. We searched the PubMed, Embase and Web of Science databases and included all case-control trials that reported on the clinical outcomes of osteonecrosis progression, incidence of total hip arthroplasty and improvement in Harris hip scores. Overall, seven case-control trials were included. Compared with the controls, patients treated with the bone marrow stem cells implantation treatment showed improved clinical outcomes with delayed osteonecrosis progression (odds ratio = 0.17, 95% CI: 0.09 - 0.32; p <0.001), a lower total hip arthroplasty incidence (odds ratio = 0.30, 95% CI: 0.12 - 0.72; p <0.01) and increased Harris hip scores (mean difference = 4.76, 95% CI: 1.24 - 8.28; p<0.01). The heterogeneity, publication bias, and sensitivity analyses showed no statistical difference significant differences between studies. Thus, our study suggests that autologous bone marrow stem cells implantation has a good therapeutic effect on osteonecrosis of the femoral, resulting in beneficial clinical outcomes. However, trials with larger sample sizes are needed to confirm these findings.

Parathyroid Hormone (PTH) Induces Autophagy to Protect Osteocyte Cell Survival from Dexamethasone Damage

BACKGROUND Glucocorticoids (GC) have direct adverse effects on osteocytes, the most abundant bone cell type, and play an important role in osteonecrosis of the femoral head (ONFH). Teriparatide has been reported to be an effective treatment for ONFH. However, the underlying mechanism is unclear. MATERIAL AND METHODS An osteocyte cell line, MLO-Y4, was used under various doses of dexamethasone (Dex) with or without rhPTH (1-34). Cell viability, autophagy, and apoptosis markers and osteocyte characteristic mRNAs were investigated to better understand this phenomenon. RESULTS Induction of apoptosis by Dex was increased in a time- and dose-dependent manner in MLO-Y4 cells. Autophagy markers (LC3-II and Beclin-1) were increased at the low dose of Dex (10^-7 or 10^-6 M) and decreased at the high dose (10^-5 M). In MOL-Y4 cells, rhPTH (1-34) was shown to be protective against Dex-induced apoptosis. The upregulation of LC3-II and Beclin-1 and decreased level of Caspase-3 was observed in the rhPTH (1-34)-treated group compared with the Dex-only-treated group. Furthermore, the changes induced by Dex in osteocytes, such as increased SOST, RANKL, and DMP-1 mRNA level and decreased Destrin mRNA level, were reversed by rhPTH (1-34). A similar result was found in osteocyte-specific proteins sclerostin expression encoded by SOST mRNA, which acted as a bone formation inhibitor. CONCLUSIONS The self-activation of autophagy may be a protective mechanism against apoptosis induced by Dex. The protection effect of rhPTH (1-34) for GC-induced ONFH thus results, at least in part, from enhanced autophagy.