Background and Purpose
Increasing evidence suggests systemic inflammation‐caused skeletal muscle atrophy as a major clinical feature of cachexia. Triptolide obtained from Tripterygium wilfordii Hook ...F possesses potent anti‐inflammatory and immunosuppressive effects. The present study aims to evaluate the protective effects and molecular mechanisms of triptolide on inflammation‐induced skeletal muscle atrophy.
Experimental Approach
The effects of triptolide on skeletal muscle atrophy were investigated in LPS‐treated C2C12 myotubes and C57BL/6 mice. Protein expressions and mRNA levels were analysed by western blot and qPCR, respectively. Skeletal muscle mass, volume and strength were measured by histological analysis, micro‐CT and grip strength, respectively. Locomotor activity was measured using the open field test.
KEY RESULTS
Triptolide (10–100 fM) up‐regulated protein synthesis signals (IGF‐1/p‐IGF‐1R/IRS‐1/p‐Akt/p‐mTOR) and down‐regulated protein degradation signal atrogin‐1 in C2C12 myotubes. In LPS (100 ng·ml−1)‐treated C2C12 myotubes, triptolide up‐regulated MyHC, IGF‐1, p‐IGF‐1R, IRS‐1 and p‐Akt. Triptolide also down‐regulated ubiquitin‐proteasome molecules (n‐FoxO3a/atrogin‐1/MuRF1), proteasome activity, autophagy‐lysosomal molecules (LC3‐II/LC3‐I and Bnip3) and inflammatory mediators (NF‐κB, Cox‐2, NLRP3, IL‐1β and TNF‐α). However, AG1024, an IGF‐1R inhibitor, suppressed triptolide‐mediated effects on MyHC, myotube diameter, MuRF1 and p62 in LPS‐treated C2C12 myotubes. In LPS (1 mg·kg−1, i.p.)‐challenged mice, triptolide (5 and 20 μg·kg−1·day−1, i.p.) decreased plasma TNF‐α levels and it increased skeletal muscle volume, cross‐sectional area of myofibers, weights of the gastrocnemius and tibialis anterior muscles, forelimb grip strength and locomotion.
Conclusions and Implications
These findings reveal that triptolide prevented LPS‐induced inflammation and skeletal muscle atrophy and have implications for the discovery of novel agents for preventing muscle wasting.
Aging has less effect on adipose‐derived mesenchymal stem cells (ADSCs) than on bone marrow‐derived mesenchymal stem cells (BMSCs), but whether the fact holds true in stem cells from elderly patients ...with osteoporotic fractures is unknown. In this study, ADSCs and BMSCs of the same donor were harvested and divided into two age groups. Group A consisted of 14 young patients (36.4 ± 11.8 years old), and group B consisted of eight elderly patients (71.4 ± 3.6 years old) with osteoporotic fractures. We found that the doubling time of ADSCs from both age groups was maintained below 70 hrs, while that of BMSCs increased significantly with the number of passage. When ADSCs and BMSCs from the same patient were compared, there was a significant increase in the doubling time of BMSCs in each individual from passages 3 to 6. On osteogenic induction, the level of matrix mineralization of ADSCs from group B was comparable to that of ADSCs from group A, whereas BMSCs from group B produced least amount of mineral deposits and had a lower expression level of osteogenic genes. The p21 gene expression and senescence‐associated β‐galactosidase activity were lower in ADSCs compared to BMSCs, which may be partly responsible for the greater proliferation and differentiation potential of ADSCs. It is concluded that the proliferation and osteogenic differentiation of ADSCs were less affected by age and multiple passage than BMSCs, suggesting that ADSCs may become a potentially effective therapeutic option for cell‐based therapy, especially in elderly patients with osteoporosis.
Aims
Type 2 diabetes mellitus (T2DM) frequently co‐exists with osteoporosis and dyslipidemia. Statins have been commonly used in the treatment of dyslipidemia. Recent studies have indicated a ...therapeutic role of statins in decreasing the risk of osteoporosis and fractures, but conflicting results have been reported. This study investigated the association between statin use and hip fracture (HFx) risk among T2DM patients.
Materials and Methods
A retrospective Taiwan population‐based propensity‐matched cohort study was performed using the Diabetes Mellitus Health Database from Taiwan National Health Insurance Research Database. Patients with newly diagnosed with T2DM between 2010 and 2014 were identified. Patients who previously used statins and had ever suffered HFx before the index date were excluded. HFx that occurred from 2010 to 2019 was collected to compute the cumulative rate of HFx. Hazard ratios (HRs) were calculated for the HFx risk according to the use or non‐use of statins. To evaluate the dose–effect relationship of statins, sensitivity analyses were conducted.
Results
After propensity score matching for age and sex, 188,588 patients were identified as statin users and non‐statin users. Statin use after T2DM diagnosis was associated with a decreased HFx risk with an adjusted HR (aHR) of 0.69 (P < 0.001). A dose–effect relationship was identified. The aHRs for developing HFx were 1.29, 0.67, and 0.36 for patients who used 28–174, 175–447, and >447 cumulative defined daily doses of statins, respectively (P < 0.001).
Conclusions
Statin use in adults with T2DM showed a lower risk of HFx by demonstrating a dose–response relationship.
Nanoparticles (NP) that target bone tissue were developed using PLGA-PEG (poly(lactic-co-glycolic acid)-polyethylene glycol) diblock copolymers and bone-targeting moieties based on aspartic acid, ...(Asp)(n(1,3)). These NP are expected to enable the transport of hydrophobic drugs. The molecular structures were examined by (1)H NMR or identified using mass spectrometry and Fourier transform infrared (FT-IR) spectra. The NP were prepared using the water miscible solvent displacement method, and their size characteristics were evaluated using transmission electron microscopy (TEM) and dynamic light scattering. The bone targeting potential of the NP was evaluated in vitro using hydroxyapatite affinity assays and in vivo using fluorescent imaging in zebrafish and rats. It was confirmed that the average particle size of the NP was <200 nm and that the dendritic Asp3 moiety of the PLGA-PEG-Asp3 NP exhibited the best apatite mineral binding ability. Preliminary findings in vivo bone affinity assays in zebrafish and rats indicated that the PLGA-PEG-ASP3 NP may display increased bone-targeting efficiency compared with other PLGA-PEG-based NP that lack a dendritic Asp3 moiety. These NP may act as a delivery system for hydrophobic drugs, warranting further evaluation of the treatment of bone disease.
Injectable thermoresponsive hydrogels have the advantages of effective cell delivery and minimal invasion for tissue engineering applications. In this study, we investigated the chondroinductive ...potential of newly developed hyaluronic acid (HA)-modified thermoresponsive poly(N-isopropylacrylamide) (HA-PNIPAAm-CL) hydrogels on enhancing rabbit ADSC (rADSC) chondrogenesis in vitro and in the synovial cavity of rabbit. The HA-mixed PNIPAAm (HA-PNIPAAm-CP) and HA-cross-linked PNIPAAm (HA-PNIPAAm-CL) were fabricated using physical interaction and chemical cross-linking methods, respectively. The in vitro results showed that, compared to unmodified PNIPAAm, both HA-modified hydrogels significantly increased cell viability, chondrogenic marker gene (aggrecan and type II collagen) expression and sulfide glycosaminoglycan (sGAG) formation in embedded rADSCs. However, HA-PNIPAAm-CL showed the highest rADSC viability and chondrogenesis. The chondrogenic effects of HA-modified hydrogels on rADSCs were confirmed in vivo by the intraarticular injection of hydrogel-embedded rADSC constructs into rabbit synovial cavities for 3 weeks and tracing with CM-DiI labeling. Neocartilage formation in the hydrogels was determined by histomorphological staining of GAG and type II collagen. In vivo injected rADSC/HA-PNIPAAm-CL constructs showed more hyaline cartilage formation than that of rADSC/HA-PNIPAAm-CP and rADSC/PNIPAAm constructs in the synovial cavity of rabbit. These results suggest that the HA-PNIPAAm-CL provides a suitable microenvironment to enhance ADSC chondrogenesis for articular cartilage tissue engineering applications.
Cell-matrix adhesion is one of the important interactions that regulates stem cell survival, self-renewal, and differentiation. Our previous report (Wu SC, Chang JK, Wang CK, Wang GJ, Ho ML. ...Biomaterials 31: 631-640, 2010) indicated that a microenvironment enriched with hyaluronan (HA) initiated and enhanced chondrogenesis in human adipose-derived stem cells (hADSCs). We further hypothesize that HA-induced chondrogenesis in hADSCs is mainly due to the interaction of HA and CD44 (HA-CD44), a cell surface receptor of HA. The HA-CD44 interaction was tested by examining the mRNA expression of hyaluronidase-1 (Hyal-1) and chondrogenic marker genes (SOX-9, collagen type II, and aggrecan) in hADSCs cultured on HA-coated wells. Cartilaginous matrix formation, sulfated glycosaminoglycan, and collagen productions by hADSCs affected by HA-CD44 interaction were tested in a three-dimensional fibrin hydrogel. About 99.9% of hADSCs possess CD44. The mRNA expressions of Hyal-1 and chondrogenic marker genes were upregulated by HA in hADSCs on HA-coated wells. Blocking HA-CD44 interaction by anti-CD44 antibody completely inhibited Hyal-1 expression and reduced chondrogenic marker gene expression, which indicates that HA-induced chondrogenesis in hADSCs mainly acts through HA-CD44 interaction. A 2-h preincubation and coculture of cells with HA in hydrogel (HA/fibrin hydrogel) not only assisted in hADSC survival, but also enhanced expression of Hyal-1 and chondrogenic marker genes. Higher levels of sulfated glycosaminoglycan and total collagen were also found in HA/fibrin hydrogel group. Immunocytochemistry showed more collagen type II, but less collagen type X, in HA/fibrin than in fibrin hydrogels. Our results indicate that signaling triggered by HA-CD44 interaction significantly contributes to HA-induced chondrogenesis and may be applied to adipose-derived stem cell-based cartilage regeneration.
Pulsed electromagnetic field (PEMF) has been successfully applied to accelerate fracture repair since 1979. Recent studies suggest that PEMF might be used as a nonoperative treatment for the early ...stages of osteonecrosis. However, PEMF treatment requires a minimum of ten hours per day for the duration of the treatment. In this study, we modified the protocol of the single-pulsed electromagnetic field (SPEMF) that only requires a 3-minute daily treatment. In the in vitro study, cell proliferation and osteogenic differentiation was evaluated in the hBMSCs. In the in vivo study, new bone formation and revascularization were evaluated in the necrotic bone graft. Results from the in vitro study showed no significant cytotoxic effects on the hBMSCs after 5 days of SPEMF treatment (1 Tesla, 30 pulses per day). hBMSC proliferation was enhanced in the SPEMF-treated groups after 2 and 4 days of treatment. The osteogenic differentiation of hBMSCs was significantly increased in the SPEMF-treated groups after 3-7 days of treatment. Mineralization also increased after 10, 15, 20, and 25 days of treatment in SPEMF-treated groups compared to the control group. The 7-day short-course treatment achieved similar effects on proliferation and osteogenesis as the 25-day treatment. Results from the in vivo study also demonstrated that both the 7-day and 25-day treatments of SPEMF increased callus formation around the necrotic bone and also increased new vessel formation and osteocyte numbers in the grafted necrotic bone at the 2nd and 4th weeks after surgery. In conclusion, the newly developed SPEMF accelerates osteogenic differentiation of cultured hBMSCs and enhances bone repair, neo-vascularization, and cell growth in necrotic bone in mice. The potential clinical advantage of the SPEMF is the short daily application and the shorter treatment course. We suggest that SPEMF may be used to treat fractures and the early stages of osteonecrosis.
Discoidin domain receptor 1 (
) is a collagen-binding membrane protein, but its role in osteoblasts during osteogenesis remains undefined. We generated inducible osteoblast-specific
knockout (OKOΔ
) ...mice; their stature at birth, body weight and body length were significantly decreased compared with those of control
mice. We hypothesize that
regulates osteogenesis of osteoblasts. Micro-CT showed that compared to 4-week-old
mice, OKOΔ
mice presented significant decreases in cancellous bone volume and trabecular number and significant increases in trabecular separation. The cortical bone volume was decreased in OKOΔ
mice, resulting in decreased mechanical properties of femurs compared with those of
mice. In femurs of 4-week-old OKOΔ
mice, H&E staining showed fewer osteocytes and decreased cortical bone thickness than
. Osteoblast differentiation markers, including BMP2, Runx2, alkaline phosphatase (ALP), Col-I and OC, were decreased compared with those of control mice.
knockdown in osteoblasts resulted in decreased mineralization, ALP activity, phosphorylated p38 and protein levels of BMP2, Runx2, ALP, Col-I and OC during osteogenesis. Overexpression and knockdown of
in osteoblasts demonstrated that DDR1 mediates the expression and activity of Runx2 and the downstream osteogenesis markers during osteogenesis through regulation of p38 phosphorylation.
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