P-glycoprotein overexpression in bone marrow-derived multipotent stromal cells decreases the risk of steroid-induced osteonecrosis in the femoral head

P-glycoprotein (P-gp) plays a role in steroid-induced osteonecrosis of the femoral head (ONFH), but the underlying mechanism remains unknown. We hypothesized that P-gp overexpression can prevent ONFH by regulating bone marrow-derived multipotent stromal cell (BMSC) adipogenesis and osteogenesis. BMSCs from Sprague-Dawley rats were transfected with green fluorescent protein (GFP) or the multidrug resistance gene 1 (MDR1) encoding GFP and P-gp. Dexamethasone was used to induce BMSC differentiation. Adipogenesis was determined by measuring peroxisome proliferator-activated receptor (PPAR-γ) expression and the triglyceride level. Osteogenesis was determined by measuring runt-related transcription factor 2 (Runx2) expression and alkaline phosphatase activity. For in vivo experiments, rats were injected with saline, BMSCs expressing GFP (GFP-BMSCs) or BMSCs expressing GFP-P-gp (MDR1-GFP-BMSCs). After dexamethasone induction, adipogenesis was determined by measuring PPAR-γ expression and fatty marrow, whereas osteogenesis was detected by measuring Runx2 expression, trabecular parameters and the mineral apposition rate, followed by evaluation of the incidence of ONFH. Overexpression of P-gp in BMSCs resulted in markedly decreased expression of adipogenic markers and increased expression of osteogenic markers. Compared with rats injected with saline, rats injected with GFP-BMSCs showed reduced ONFH, and the injected GFP-positive BMSCs attached to trabecular surfaces and exhibited an osteoblast-like morphology. Compared with the rats injected with BMSCs expressing GFP alone, rats injected with BMSCs overexpressing GFP and P-gp showed lower adipocytic variables, higher osteogenic variables and lower incidence of ONFH. Overexpression of P-gp inhibited BMSC adipogenesis and promoted osteogenesis, which reduced the incidence of steroid-induced ONFH.

CLOCK regulates Drp1 mRNA stability and mitochondrial homeostasis by interacting with PUF60

Circadian genes such as Clock, Bmal1, Cryptochrome1/2, and Period1/2/3 constitute the precise circadian system. ClockΔ19 is a commonly used mouse model harboring a circadian clock gene mutation, which lacks the EXON-19-encoded 51 amino acids. Previous reports have shown that ClockΔ19 mice have severe metabolic abnormalities. Here, we report that the mitochondria of ClockΔ19 mice exhibit excessive fission and dysfunction. We also demonstrate that CLOCK binds to the RNA-binding protein PUF60 through its EXON 19. Further, we find that PUF60 directly maintains mitochondrial homeostasis through regulating Drp1 mRNA stability, while the association with CLOCK can competitively inhibit this function. In ClockΔ19 mice, CLOCKΔ19 releases PUF60, leading to enhanced Drp1 mRNA stability and persistent mitochondrial fission. Our results reveal a direct post-transcriptional role of CLOCK in regulating mitochondrial homeostasis via Drp1 mRNA stability and that the loss of EXON 19 of CLOCK in ClockΔ19 mice leads to severe mitochondrial homeostasis disorders.

Evaluation of efficacy and safety of percutaneous transforaminal endoscopic surgery (PTES) for surgical treatment of calcified lumbar disc herniation: a retrospective cohort study of 101 patients

BACKGROUND

Percutaneous transforaminal endoscopy has been widely used to treat lumbar disc herniation (LDH), but the steep learning curve and difficulties in removing the calcified disc hinders the application of conventional endoscopy in treating calcified lumbar disc herniation (CLDH). In 2017, we first reported Percutaneous Transforaminal Endoscopic Surgery (PTES) as an easy-to-learn posterolateral transforaminal endoscopic technique to decompress the nerve root for LDH. We used our PTES technique to remove the calcified LDH and the purpose of this study is to evaluate the safety and efficacy of this technique.

METHODS

Forty-six patients with CLDH and fifty-five patients with uncalcified lumbar disc herniation (ULDH) underwent PTES to decompress the nerve root. Visual analogue scale was collected before the surgery, immediately, one week, one month, two months, three months, six months, 12 months and 24 months after surgery. The outcomes of MacNab classification were collected 24 months after surgery. Intra- and Post-operative complications were also recorded.

RESULTS

For CLDH patients, the VAS score was 9 (5-10) before operation, and then dropped to 2 (1-4) after surgery. VAS score continually decreased to 0 (0-3) at 24 months after surgery. 95.65% of CLDH patients showed excellent or good outcomes. ULDH group showed similar MacNab classification (94.55%) and VAS changing curve. The therapeutic effect of PTES in treating CLDH was as good as that in treating uncalcified patients.

CONCLUSIONS

PTES is an effective and safe method to treat calcified lumbar disc herniation.

Regulatory effect of microRNA-34a on osteogenesis and angiogenesis in glucocorticoid-induced osteonecrosis of the femoral head

Glucocorticoid-induced osteonecrosis of the femoral head (GIOFH) is a common and devastating orthopedic disease, and its underlying mechanism remains unclear. The aim of this study was to determine the role of microRNA-34a (mir-34a) in GIOFH. C57 mouse mesenchymal stem cells (mMSCs) and human umbilical vein endothelial cells (HUVECs) were cultured with dexamethasone (Dex). A total of 48 adult rats were treated with glucocorticoids, and after the onset of GIOFH, each femoral head was removed. Mir-34a mimics, an inhibitor and over-expressing lentivirus were used in vitro and in vivo, respectively. Real-time PCR, immunohistochemistry, ELISA, cell proliferation assays, osteoblastic differentiation, and endothelial activity assays were employed to evaluate the effect of mir-34a on mMSCs, osteoblasts, and vascular endothelial cells in glucocorticoid-treated mice. We found that Dex inhibited mMSC proliferation and osteoblastic differentiation, as well as the viability and activity of endothelial cells. Dex also caused osteonecrosis and decreased new vessel formation in vivo. Mir-34a alleviated the inhibitory effects of Dex on mMSCs and osteoblasts, while facilitating its inhibitory effects on endothelial cells. Mir-34a is an important regulator in osteogenesis and angiogenesis, and it might be useful as a therapeutic target for GIOFH. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:417-424, 2018.

Failure of xenoimplantation using porcine synovium-derived stem cell-based cartilage tissue constructs for the repair of rabbit osteochondral defects

The use of xenogeneic tissues offers many advantages with respect to availability, quality control, and timing of tissue harvest. Our previous study indicated that implantation of premature tissue constructs from allogeneic synovium-derived stem cells (SDSCs) facilitated cartilage tissue regeneration. The present study investigated the feasibility of xenoimplantation of SDSC-based premature tissue constructs for the repair of osteochondral defects. Porcine SDSCs were mixed with fibrin gel, seeded in polyglycolic acid (PGA) scaffolds, and cultured in a rotating bioreactor system supplemented for 1 month with growth factor cocktails. The engineered porcine premature tissues were implanted to repair surgically induced osteochondral defects in the medial femoral condyles of 12 rabbits. Three weeks after surgery, the xenoimplantation group exhibited a smooth, whitish surface while the untreated control remained empty. Surprisingly, 6 months after surgery, the xenoimplantation group displayed some tissue loss while the untreated control group was overgrown with fibrocartilage tissue. In the xenoimplantation group, chronic inflammation was observed in synovial tissue where porcine major histocompatibility complex (MHC) class II antigen positively stained in the engulfed foreign bodies. In addition, porcine source cells also migrated from the implantation site and may have been responsible for the observed loss of glycosaminoglycans (GAGs) underneath surrounding articular cartilage. The histological score was much worse in the xenoimplanted group than in the untreated control. Our study suggested that SDSC-based xenogeneic tissue constructs might cause delayed immune rejection. Xenotransplantation may not be an appropriate approach to repair osteochondral defects.

The circadian protein CLOCK regulates cell metabolism via the mitochondrial carrier SLC25A10

Physiological function and metabolic regulation are the most important outputs of circadian clock controls in mammals. Mitochondrial respiration and ROS production show rhythmic activity. Mitochondrial carriers, which are responsible for mitochondrial substance transfer, are vital for mitochondrial metabolism. Clock (Circadian Locomotor Output Cycles Kaput) is the first core circadian gene identified in mammalian animals. However, whether CLOCK protein can regulate mitochondrial functions via mitochondrial carriers is unclear. Here, we showed that CLOCK can bind to the mitochondrial carrier SLC25A10. For further analysis, we established a Slc25a10-/--Hepa1-6 cell line using CRISPR/Cas9 gene-editing technology. Slc25a10-/--Hepa1-6 cells showed disordered glucose homeostasis, increased oxidative stress levels, and damaged electron transport chains. Next, using an immunoprecipitation assay, we found that amino acids 43-84 and 169-210 in SLC25A10 are key sites that respond to CLOCK binding. Finally, forced expression of wild-type SLC25A10 in Slc25a10-/--Hepa1-6 cells could compensate for the loss of SLC25A10; the decreased glucose metabolism, severe oxidative stress and damaged electron transport chain were recovered. In addition, a mutant Slc25a10 with changes in two key sites did not show a rescue effect. In conclusion, we identified a new protein-protein interaction mechanism in which CLOCK can directly regulate cell metabolism via the mitochondrial membrane transporter SLC25A10. Our study might provide some new insights into the relationship between circadian clock and mitochondrial metabolism.

Modified total en bloc spondylectomy in thoracic vertebra tumour

Total en bloc spondylectomy (TES) for vertebral tumour was previously reported by Tomita through a single posterior approach using a T-saw. A modified total en bloc spondylectomy (MTES) technique is reported in the present study. The disc puncture needle with a sleeve was used to obliquely puncture from the posterior to the anterior direction. A T-saw was inserted through the sleeve and led out to the operator's side by the leading clamp. The disc was partially cut with the saw from its medial to lateral aspect. After a spinal fixation rod was applied on the operator's side, the residual discs on the opposite side were cut as described above. Six patients with thoracic vertebral tumours were operated on using the MTES technique. Five patients showed improvement in their neurological deficits postoperatively. There was no evidence of tumour recurrence at the final follow-up. The MTES is technically feasible with improved practicality and safety.

One-step cross-linked injectable hydrogels with tunable properties for space-filling scaffolds in tissue engineering

One-step cross-linked injectable hydrogels are prepared through Schiff-based reaction with tunable properties for space-filling scaffolds.

Reciprocal effect of microRNA-224 on osteogenesis and adipogenesis in steroid-induced osteonecrosis of the femoral head

The adverse effects of glucocorticoids (GCs) on bone marrow stromal stem cells (BMSCs) play an important role in steroid-induced osteonecrosis of the femoral head (ONFH). Our previous miRNA microarray analysis indicated that microRNA-224-5p (miR-224-5p) could be a potential regulator; however, the underlying mechanism remains unclear. In the present study, we demonstrated that miR-224-5p was upregulated in GC-treated BMSCs, and functional experiments revealed that miR-224-5p could suppress osteogenic but promote adipogenic differentiation of BMSCs. Smad4 was identified as a direct target gene of miR-224-5p, and the Smad4-Taz axis was confirmed as the regulatory pathway for adipo-osteogenic differentiation of BMSCs. Our in vivo experiments further confirmed that the miR-224-5p antagomir could alleviate the inhibitory effects of GCs and facilitate bone formation in steroid-induced ONFH models. Therefore, these findings provide insight into the function of miR-224-5p as a reciprocal regulator of the adipo-osteogenic differentiation of BMSCs, and it could serve as a novel therapeutic target for steroid-induced ONFH.

CLOCK promotes 3T3-L1 cell proliferation via Wnt signaling

Circadian genes control most of the physiological functions including cell cycle. Cell proliferation is a critical factor in the differentiation of progenitor cells. However, the role of Clock gene in the regulation of cell cycle via wingless-type (Wnt) pathway and the relationship between Clock and adipogenesis are unclear. We found that the circadian locomotor output cycles kaput (Clock) regulated the proliferation and the adipogenesis of 3T3-L1 preadipocytes. We found that Clock attenuation inhibited the viability of 3T3-L1 preadipocytes in the cell counting kit 8. The expression of c-Myc and Cyclin D1 decreased dramatically in 3T3-L1 when Clock was silenced with short interfering RNA and was also decreased in fat tissue and adipose tissue-derived stem cells of Clock(Δ19) mice. Clock directly controls the expression of the components of Wnt signal transduction pathway, which was verified by serum shock, chromatin immunoprecipitation, Western blot, and quantitative real-time polymerase chain reaction (qRT-PCR). Furthermore, IWR-1, a Wnt signal pathway inhibitor, inhibited the cell cycle promotion by CLOCK, which was detected by cell viability assay, flow cytometry, and qRT-PCR. Therefore, CLOCK transcription control of Wnt signaling promotes cell cycle progression in 3T3-L1 preadipocytes. Clock inhibited the adipogenesis on day 2 in 3T3-L1 cells via Oil Red O staining and qRT-PCR detection and probably related to cellular differentiation. These data provide evidence that the circadian gene Clock regulates the proliferation of preadipocytes and affects adipogenesis. © 2016 IUBMB Life, 68(7):557-568, 2016.

Impact of Fibronectin Knockout on Proliferation and Differentiation of Human Infrapatellar Fat Pad-Derived Stem Cells

Fibronectin plays an essential role in tissue development and regeneration. However, the effects of fibronectin knockout (FN1-KO) on stem cells' proliferation and differentiation remain unknown. In this study, CRISPR/Cas9 generated FN1-KO in human infrapatellar fat pad-derived stem cells (IPFSCs) was evaluated for proliferation ability including cell cycle and surface markers as well as stemness gene expression and for differentiation capacity including chondrogenic and adipogenic differentiation. High passage IPFSCs were also evaluated for proliferation and differentiation capacity after expansion on decellularized ECM (dECM) deposited by FN1-KO cells. Successful FN1-KO in IPFSCs was confirmed by Sanger sequencing and Inference of CRISPR Edits analysis (ICE) as well as immunostaining for fibronectin expression. Compared to the GFP control, FN1-KO cells showed an increase in cell growth, percentage of cells in the S and G2 phases, and CD105 and CD146 expression but a decrease in expression of stemness markers CD73, CD90, SSEA4, and mesenchymal condensation marker CDH2 gene. FN1-KO decreased both chondrogenic and adipogenic differentiation capacity. Interestingly, IPFSCs grown on dECMs deposited by FN1-KO cells exhibited a decrease in cell proliferation along with a decline in CDH2 expression. After induction, IPFSCs plated on dECMs deposited by FN1-KO cells also displayed decreased expression of both chondrogenic and adipogenic capacity. We concluded that FN1-KO increased human IPFSCs' proliferation capacity; however, this capacity was reversed after expansion on dECM deposited by FN1-KO cells. Significance of fibronectin in chondrogenic and adipogenic differentiation was demonstrated in both FN1-KO IPFSCs and FN(-) matrix microenvironment.

Cell surface heat shock protein 90 modulates prostate cancer cell adhesion and invasion through the integrin-β1/focal adhesion kinase/c-Src signaling pathway

Heat shock protein (Hsp) 90 is a molecular chaperone that maintains the active conformation and function of numerous client oncoproteins in cancer cells. Hsp90 has also been detected on the plasma membrane of cells, and its expression has been suggested to correlate with metastatic potential. We studied the PC3 cell line, which is a highly invasive human prostate cancer cell line, and confirmed that Hsp90 is present on the cell surface of PC3 cells. Interestingly, cell surface Hsp90 was also specifically localized at the leading edge of migrating cells. By using a specific antibody that inhibited cell surface Hsp90, adhesion and invasion of PC3 cells were significantly suppressed in vitro. Concomitantly with these findings, we demonstrated that the inhibition of cell surface Hsp90 not only inhibited the FN-dependent association between FAK, c-Src and integrin β1, but also significantly inhibited the phosphorylation of FAK and c-Src, as well as their downstream targets paxillin and p130Cas. Additionally, the Hsp90 antibody reversed cell invasion stimulated by overexpression of FAK. These data indicate that cell surface Hsp90 is involved in prostate cancer cell invasion through the integrin β1/FAK/c-Src signaling pathway. Our study provides new insights into the mechanisms of cell surface Hsp90 in cancer invasion. These results suggest that molecular targeting of cell surface Hsp90 may therefore be a novel target for the effective treatment of metastatic prostate cancer.

Stat3 upregulates leucine-rich repeat-containing g protein-coupled receptor 4 expression in osteosarcoma cells

The activation of signal transducer and activator of transcription 3 (Stat3) signaling is the common hallmark in various human cancers including osteosarcoma. In the present study, according to PCR-based microarrays using cDNA prepared from interleukin-6 (IL-6) treated osteosarcoma cells, we found that leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4) was a transcriptional target of Stat3. Overexpression of Stat3 promoted LGR4 expression, while its deficiency using small interfering RNA (siRNA) reduced LGR4 expression. Furthermore, we identified a Stat3 binding motif located at -556 to -549 bp in the LGR4 promoter that is able to interact with Stat3. Thus, our results suggest a previously unknown Stat3-LGR4 molecular network, which may control osteosarcoma development and progression.

Predictive value of single photon emission computerized tomography and computerized tomography in osteonecrosis after femoral neck fracture: a prospective study

PURPOSE

Osteonecrosis of the femoral head (ONFH) is a very common complication after femoral neck fracture. The purpose of this study was to assess the femoral head vascularity after femoral neck fracture using single photon emission computerized tomography and computerized tomography (SPECT/CT), and to evaluate its value in predicting ONFH.

METHODS

Between January 2008 and March 2011, 120 patients diagnosed with femoral neck fracture underwent SPECT-CT before the internal fixation. The fracture was classified according to the Garden classification. The ratios of the radionuclide uptake of the fractured femoral head to that of the contralateral femoral head (F/N) were calculated to assess the femoral head vascularity. After a minimum of two years' follow-up, magnetic resonance imaging (MRI) was used as the "gold standard" for the diagnosis of possible ONFH.

RESULTS

A total of 114 patients completed the study. The SPECT/CT examination showed that the F/N ratios of Garden I, II, III and IV were 2.6, 1.8, 0.8, and 0.6, respectively. At the time of the most recent follow-up, osteonecrosis developed in two of the 27 patients who had a Garden Stage-II fracture, in eight of the 34 patients who had a Garden Stage-III fracture, and nine of the 27 patients who had a Garden Stage-VI fracture. With a cutoff of 0.55 from the receiver operating characteristic (ROC) curve, F/N ratio showed a sensitivity of 97%, a specificity of 79%, a positive predictive value of 95%, and a negative predictive value of 19%.

CONCLUSION

SPECT-CT proved to be reliable and valid for predicting ONFH after femoral neck fracture.

Serum Biomarkers Related to Glucocorticoid-Induced Osteonecrosis of the Femoral Head: A Prospective Nested Case-Control Study

Early diagnosis and prevention of glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH) continues to be a challenging problem for clinicians and researchers. However, the role of circulating biomarkers for GC-induced ONFH, which may reveal individual susceptibility and facilitate earlier diagnosis, remains to be determined. The aim of this study was to identify potential biomarkers that may predict early GC-induced ONFH. A total of 123 patients scheduled for initial systemic GC therapy were enrolled in this prospective nested case-control study. The serum concentrations of 13 potential biomarkers were measured in seven patients with GC-induced ONFH, diagnosed instantly after short-term use of GCs and in 20 controls who did not develop osteonecrosis despite similar GC therapy. Biomarkers were measured both before and after taking GCs to identify any differences in marker levels and the changes during GC therapy between two groups. Type I collagen cross-linked C-telopeptide (β-CTX; p = 0.000) was significantly lower, high-density lipoprotein cholesterol (p = 0.092) and apolipoprotein (apo)-B/apo-A1 (p = 0.085) tended to be lower and higher, respectively, before GC treatment in osteonecrosis group. After GC therapy, β-CTX (p = 0.014) was significantly lower and amino terminal telopeptide of procollagen type I (PINP; p = 0.068) tended to be lower in the osteonecrosis group. As secondary outcomes, we observed remarkable changes in nine potential biomarkers following short-term GC therapy in both groups. In conclusion, we found that β-CTX, could potentially be used to predict GC-induced ONFH before GC therapy. Lower β-CTX and PINP are promising biomarkers for the early diagnosis of GC-induced ONFH. These findings need to be confirmed in large-scale prospective studies. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2348-2357, 2019.

Rifampin suppresses osteoclastogenesis and titanium particle-induced osteolysis via modulating RANKL signaling pathways

Wear particles liberated from the surface of prostheses are considered to be main reason for osteoclast bone resorption and that extensive osteoclastogenesis leads to peri-implant osteolysis and subsequent prosthetic loosening. The aim of this study was to assess the effect of rifampin on osteoclastogenesis and titanium (Ti) particle-induced osteolysis. The Ti particle-induced osteolysis mouse calvarial model and bone marrow-derived macrophages (BMMs) were used. Rifampin, at dose of 10 or 50 mg/kg/day, was respectively given intraperitoneally for 14 days in vivo. The calvariae were removed and processed for Further histological analysis. In vitro, osteoclasts were generated from mouse BMMs with receptor activator of nuclear factor-κB ligand (RANKL) and the macrophage colony stimulating factor. Rifampin at different concentrations was added to the medium. The cell viability, tartrate-resistant acid phosphatase (TRAP) staining, TRAP activity and resorption on bone slices were analysis. Osteoclast-specific genes and RANKL-induced MAPKs signaling were tested for further study of the mechanism. Rifampin inhibited Ti-induced osteolysis and osteoclastogenesis in vivo. In vitro data indicated that rifampin suppressed osteoclast differentiation and bone resorption in a dose-dependent manner. Moreover, rifampin significantly reduced the expression of osteoclast-specific markers, including TRAP, cathepsin K, V-ATPase d2, V-ATPase a3, c-Fos, and nuclear factor of activated T cells (NFAT) c1. Further investigation revealed that rifampin inhibited osteoclast formation by specifically abrogating RANKL-induced p38 and NF-κB signaling. Rifampin had significant potential for the treatment of particle-induced peri-implant osteolysis and other diseases caused by excessive osteoclast formation and function.

Altered Clock and Lipid Metabolism-Related Genes in Atherosclerotic Mice Kept with Abnormal Lighting Condition

Background. The risk of atherosclerosis is elevated in abnormal lipid metabolism and circadian rhythm disorder. We investigated whether abnormal lighting condition would have influenced the circadian expression of clock genes and clock-controlled lipid metabolism-related genes in ApoE-KO mice. Methods. A mouse model of atherosclerosis with circadian clock genes expression disorder was established using ApoE-KO mice (ApoE-KO LD/DL mice) by altering exposure to light. C57 BL/6J mice (C57 mice) and ApoE-KO mice (ApoE-KO mice) exposed to normal day and night and normal diet served as control mice. According to zeitgeber time samples were acquired, to test atheromatous plaque formation, serum lipids levels and rhythmicity, clock genes, and lipid metabolism-related genes along with Sirtuin 1 (Sirt1) levels and rhythmicity. Results. Atherosclerosis plaques were formed in the aortic arch of ApoE-KO LD/DL mice. The serum lipids levels and oscillations in ApoE-KO LD/DL mice were altered, along with the levels and diurnal oscillations of circadian genes, lipid metabolism-associated genes, and Sirt1 compared with the control mice. Conclusions. Abnormal exposure to light aggravated plaque formation and exacerbated disorders of serum lipids and clock genes, lipid metabolism genes and Sirt1 levels, and circadian oscillation.

Exosomes derived from bone marrow mesenchymal stem cells pretreated with decellularized extracellular matrix enhance the alleviation of osteoarthritis through miR-3473b/phosphatase and tensin homolog axis

BACKGROUND

Osteoarthritis (OA) is a prevalent degenerative articular disease for which there is no effective treatment. Progress has been made in mesenchymal stem cell (MSC)-based therapy in OA, and the efficacy has been demonstrated to be a result of paracrine exosomes from MSCs. Decellularized extracellular matrix (dECM) provides an optimum microenvironment for the expansion of MSCs. In the present study, we aimed to investigate whether exosomes isolated from bone marrow mesenchymal stem cells (BMSCs) with dECM pretreatment (dECM-BMSC-Exos) enhance the amelioration of OA.

METHODS

Exosomes from BMSCs with or without dECM pretreatment were isolated. We measured and compared the effect of the BMSC-Exo and dECM-BMSC-Exo on interleukin (IL)-1β-induced chondrocytes by analyzing proliferation, anabolism and catabolism, migration and apoptosis in vitro. The in vivo experiment was performed by articular injection of exosomes into DMM mice, followed by histological evaluation of cartilage. MicroRNA sequencing of exosomes was performed on BMSC-Exo and dECM-BMSC-Exo to investigate the underlying mechanism. The function of miR-3473b was validated by rescue studies in vitro and in vivo using antagomir-3473b.

RESULTS

IL-1β-treated chondrocytes treated with dECM-BMSC-Exos showed enhanced proliferation, anabolism, migration and anti-apoptosis properties compared to BMSC-Exos. DMM mice injected with dECM-BMSC-Exo showed better cartilage regeneration than those injected with BMSC-Exo. Interestingly, miR-3473b was significantly elevated in dECM-BMSC-Exos and was found to mediate the protective effect in chondrocytes by targeting phosphatase and tensin homolog (PTEN), which activated the PTEN/AKT signaling pathway.

CONCLUSIONS

dECM-BMSC-Exo can enhance the alleviation of osteoarthritis via promoting migration, improving anabolism and inhibiting apoptosis of chondrocytes by upregulating miR-3473b, which targets PTEN.

Protective effects of total saponins of panax notoginseng on steroid-induced avascular necrosis of the femoral head in vivo and in vitro

This research was designed to investigate the protective effects of TSPN on steroid-induced avascular necrosis of the femoral head (ANFH) and the likely mechanisms of those effects. As an in vivo study, TSPN was shown to be protective against steroid-induced ANFH due to the upregulation of VEGF-A. Furthermore, TSPN attenuated the apoptosis of osteocytes and reduced the expression of Caspase-3 relative to the model group. As an in vitro study, TSPN exerted a concentration-dependent protective effect against apoptosis in MC3T3-E1 cells. Moreover, TSPN (at a dose of 100 μg/mL) significantly reversed the dexamethasone-induced augmentation of Caspase-3 expression and activity. Therefore, our study demonstrated that TSPN had a protective effect against steroid-induced ANFH that was related to the upregulation of VEGF-A and the inhibition of apoptosis and Caspase-3 activation.

Effects of an avidin-biotin binding system on Schwann cells attachment, proliferation, and gene expressions onto electrospun scaffolds

Effective Schwann cells (SCs) attachment is a prerequisite for the successful construction of tissue-engineered nerve. The present study aimed to investigate the role of an avidin-biotin binding system (ABBS) for neural tissue engineering. The attachment, proliferation, and morphology of biotinylated SCs on avidin-treated scaffolds were examined, and the effects of avidin, biotin, and the avidin-biotin binding system on SCs gene expressions were also studied. The results indicated that the attachment of biotinylated SCs onto avidin-treated scaffolds was promoted obviously within a short time (10 min). Meanwhile, there were no great differences in terms of proliferation and morphology of SCs between the two groups after cultivation for 14 days. The gene expressions of S100, GDNF, BDNF, NGF, CNTF, and PMP22 were up-regulated significantly by biotin rather than aligned scaffolds or avidin. The present study demonstrated that ABBS enhanced the attachment and maturation of SCs onto the electrospun scaffolds without adverse effects on the proliferation of SCs in the long term, suggesting the potential application of ABBS in the neural tissue engineering.

Biomechanical research of medial femoral circumflex vascularized bone-grafting in the treatment of early-to-mid osteonecrosis of the femoral head: a finite element analysis

PURPOSE

Hip preservation therapy of early ONFH (Osteonecrosis of the femoral head) has emerged as one of the hot areas of research. We have optimized the procedure of traditional MFCVBG (medial femoral circumflex vascularized bone grafting) by using specialized surgical tools and used the finite element analysis to guide the implantation position of the bone flap during surgery and validate the biological mechanical stability of the modified MFCVBG.

METHODS

This study was based on the data of a male patient with left hip (ARCO stage IIB, JIC type C) hormonal ONFH. Harris score (HHS), anteroposterior and lateral hip radiographs, frog position hip radiographs and SPECT/CT of femoral head flow imaging were performed postoperatively to evaluate clinical efficacy. The patient's CT data were used to establish upper femur finite element model of the normal group, osteonecrosis group and postoperative group, respectively. The force on the femoral structure of each group was analyzed under four different loads in the gait cycle of 0.5 times the body weight (0.5 G, standing on two feet), 2.75 G (standing on one foot), 4 G (walking with the middle foot on the ground) and 7 G (walking with the toe off the ground) to validate the biological mechanical stability of the modified MFCVBG, predict femoral head collapse risk, simulate of the different healing conditions of postoperative bone flap, and analyze the postoperative effect of non-ideal surgical model.

RESULTS

According to the follow-up results, the bone flap and the inner wall of decompression channel healed well, no osteonecrosis progression, no local collapse or micro-fracture occurred in the femoral head, and the articular surface was intact and the necrosis was well repaired. According to the result of the finite element analysis, compared with the osteonecrosis group, the overall stress and displacement peak of the upper femur and the cortical bone stress peak of the femoral head in the postoperative group and normal group were significantly reducing; modified MFCVBG can significantly improve the biomechanical stability of necrotic femoral head and reduce the risk of femoral head collapse; there was no obvious abnormal stress distribution in the greater trochanter and intertrochanter region after the flap was removed; the bone flap of the complete removal of necrotic focus + long bone flap group was directly placed at the bottom of the decompression passage, and the bone flap cortical bone can provide substantial mechanical support; in theory, patients can try to reduce the load with crutches or walking aids and carry out appropriate flat activities to effectively promote the early postoperative recovery.

CONCLUSIONS

The modified MFCVBG resulted in good efficacy, safety and feasibility. The necrotic focus should be completely removed during the operation, and the long bone flap should be placed directly under the subchondral bone. For patients with better bone healing ability, a more positive attitude can be taken to promote early postoperative weight-bearing.

Identifying Patients Who Will Most Benefit from Single Photon Emission Computerized Tomography and Computerized Tomography After Femoral Neck Fracture

BACKGROUND Single photon emission computerized tomography and computerized tomography (SPECT/CT) is useful for assessing blood supply within the femoral head after femoral neck fracture, but its use in all femoral neck fracture patients is not feasible. Therefore, the present study aimed to identify the patients for whom SPECT/CT examination will be most beneficial. MATERIAL AND METHODS Sixty-five patients with a unilateral femoral neck fracture who underwent SPECT/CT examination of the hip and were treated via closed reduction and internal fixation with three screws were enrolled between January 2009 and March 2011. A decision tree model (C 5.0) was used to identify the factors that best reflect blood supply and to build a flowchart for identifying patients who would benefit from SPECT/CT. RESULTS Fracture type was most strongly associated with the Fracture/Normal (F/N) ratio, which reflects the blood supply to the fractured femoral head. Age and the time interval from injury to examination were also associated with the F/N ratio. SPECT/CT examination is most beneficial for patients with a displaced fracture, especially if they are over 58 years old and the time interval from injury to examination is less than 10 days. CONCLUSIONS Our results indicate that elderly people with a displaced fracture are most likely to benefit from SPECT/CT examination, which can show the blood supply to the femoral head within a relatively short window of time after the injury.

Matrix reverses immortalization-mediated stem cell fate determination

Primary cell culture in vitro suffers from cellular senescence. We hypothesized that expansion on decellularized extracellular matrix (dECM) deposited by simian virus 40 large T antigen (SV40LT) transduced autologous infrapatellar fat pad stem cells (IPFSCs) could rejuvenate high-passage IPFSCs in both proliferation and chondrogenic differentiation. In the study, we found that SV40LT transduced IPFSCs exhibited increased proliferation and adipogenic potential but decreased chondrogenic potential. Expansion on dECMs deposited by passage 5 IPFSCs yielded IPFSCs with dramatically increased proliferation and chondrogenic differentiation capacity; however, this enhanced capacity diminished if IPFSCs were grown on dECM deposited by passage 15 IPFSCs. Interestingly, expansion on dECM deposited by SV40LT transduced IPFSCs yielded IPFSCs with enhanced proliferation and chondrogenic capacity but decreased adipogenic potential, particularly for the dECM group derived from SV40LT transduced passage 15 cells. Our immunofluorescence staining and proteomics data identify matrix components such as basement membrane proteins as top candidates for matrix mediated IPFSC rejuvenation. Both cell proliferation and differentiation were endorsed by transcripts measured by RNASeq during the process. This study provides a promising model for in-depth investigation of the matrix protein influence on surrounding stem cell differentiation.

Evaluation of synovium-derived mesenchymal stem cells and 3D printed nanocomposite scaffolds for tissue engineering

Stem cells and scaffolds play a very important role in tissue engineering. Here, we isolated synovium-derived mesenchymal stem cells (SMSCs) from synovial membrane tissue and characterized stem-cell properties. Gelatin nanoparticles (NP) were prepared using a two-step desolvation method and then pre-mixed into different host matrix (silk fibroin (SF), gelatin (Gel), or SF-Gel mixture) to generate various 3D printed nanocomposite scaffolds (NP/SF, NP/SF-Gel, NP/Gel-1, and NP/Gel-2). The microstructure was examined by scanning electron microscopy. Biocompatibility assessment was performed through CCK-8 assay by coculturing with SMSCs at 1, 3, 7 and 14 days. According to the results, SMSCs are similar to other MSCs in their surface epitope expression, which are negative for CD45 and positive for CD44, CD90, and CD105. After incubation in lineage-specific medium, SMSCs could differentiate into chondrocytes, osteocytes and adipocytes. 3D printed nanocomposite scaffolds exhibited a good biocompatibility in the process of coculturing with SMSCs and had no negative effect on cell behavior. The study provides a strategy to obtain SMSCs and fabricate 3D printed nanocomposite scaffolds, the combination of which could be used for practical applications in tissue engineering.