Chronic Prosopis glandulosa treatment blunts neutrophil infiltration and enhances muscle repair after contusion injury

Betulin Accelerated the Functional Recovery of Injured Muscle in a Mouse Model of Muscle Contusion

Muscle contusion is an injury to muscle fibers and connective tissues. It commonly happens in impact events, and could result in pain, swelling, and limited range of motion. Diclofenac is one of commonly used nonsteroidal anti-inflammatory drugs to alleviate pain and inflammation after injury. However, it can potentially cause some side effects including gastrointestinal complications and allergy. Betulin is a lupine-type pentacyclic triterpenoid. It is showed to have valuable pharmacological effects, but the physiological effect of betulin on muscle contusion has not been reported. This study aimed to explore the therapeutic effects of betulin on muscle contusion that produced by the drop-mass method in mice. C57BL/6 mice were randomly assigned to control (no injury), only drop-mass injury (Injury), diclofenac treatment (Injury+diclofenac), and betulin treatment (Injury+betulin) groups. Injury was executed on the gastrocnemius of the right hind limb, and then phosphate-buffered saline (PBS), diclofenac, or betulin were oral gavage administrated respectively for 7 days. Results revealed that betulin significantly restored motor functions based on locomotor activity assessments, rota-rod test, and footprints analysis. Betulin also attenuated serum creatine kinase (CK) and lactate dehydrogenase (LDH) levels after muscle injury. Neutrophil infiltration was alleviated and desmin levels were increased after betulin treatment. Our data demonstrated that betulin attenuated muscle damage, alleviated inflammatory response, improved muscle regeneration, and restored motor functions after muscle contusion. Altogether, betulin may be a potential compound to accelerate the repair of injured muscle.

17beta-estradiol alleviates contusion-induced skeletal muscle injury by decreasing oxidative stress via SIRT1/PGC-1α/Nrf2 pathway

PURPOSE

This study aimed to investigate the role of 17β-estradiol (E₂) in the repair of contusion-induced myoinjury in mice and to identify the underlying molecular mechanisms.

METHODS

In vivo, contusion protocol was performed for preparing mice myoinjury model, and Injection (i.p.) of 17β-estradiol (E₂) or estrogen receptor antagonist ICI 182,780, or ovariectomy (OVX), was used to alter estrogen level of animal models. In vitro, C₂C₁₂ myoblasts were treated with H₂O₂ (oxidative stress inducer), SIRT1 inhibitor EX527, or aromatase inhibitor anastrozole. Serum E₂ level was assessed by enzyme-linked immunosorbent assay (ELISA). Muscle damage repair was evaluated by H&E staining and the activities of serum creatine kinase (CK) and lactate dehydrogenase (LDH). The oxidative stress was estimated by the levels of catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA). Western blot was performed to measure the protein expressions of SIRT1, PGC-1α, Nrf2, and HO-1.

RESULTS

We observed the elevated serum E₂ levels and the upregulated oxidative stress in damaged muscle in female mice after contusion-induction. The E₂ administration in vivo alleviated contusion-induced myoinjury in OVX mice by reducing CK and LDH activities, suppressing oxidative stress, and enhancing the expression levels of SIRT1, PGC-1α, Nrf2, and HO-1. These effects were inhibited by treatment with an ERα/β antagonist. Moreover, EX527 or anastrozole treatment exacerbated H₂O₂-induced growth inhibition and oxidative stress, and expression downregulation of SIRT1, PGC-1α, Nrf2, and HO-1 in C₂C₁₂ cells in vitro.

CONCLUSION

Our results suggest that E₂ is a positive intervention factor for muscle repair followed contusion-induced myoinjury, through its effects on suppressing oxidative stress via activating the SIRT1/PGC-1α/Nrf2 pathway.

Contusion concomitant with ischemia injury aggravates skeletal muscle necrosis and hinders muscle functional recovery

Contusion concomitant with ischemia injury to skeletal muscles is common in civilian and battlefield trauma. Despite their clinical importance, few experimental studies on these injuries are reported. The present study established a rat skeletal muscle contusion concomitant with ischemia injury model to identify skeletal muscle alterations compared with contusion injury or ischemia injury. Macroscopic and microscopic morphological evaluation showed that contusion concomitant with ischemia injury aggravated muscle edema and hematoxylin-eosin (HE) injury score at 24 h postinjury. Serum creatine kinase (CK) and lactate dehydrogenase (LDH) levels, together with gastrocnemius muscle (GM) tumor necrosis factor-alpha (TNF-α) content elevated at 24 h postinjury too. During the 28-day follow-up, electrophysiological and contractile impairment was more severe in the contusion concomitant with ischemia injury group. In addition, contusion concomitant with ischemia injury decreased the percentage of larger (600-3000 μm²) fibers and increased the fibrotic area and collagen I proportion in the GM. Smaller proportions of Pax7⁺ and MyoD⁺ satellite cells (SCs) were observed in the contusion concomitant with ischemia injury group at 7 days postinjury. In conclusion, contusion concomitant with ischemia injury to skeletal muscle not only aggravates early muscle fiber necrosis but also hinders muscle functional recovery by impairing SC differentiation and exacerbating fibrosis during skeletal muscle repair.

Bone Marrow Stromal Cell-Derived Exosomes Promote Muscle Healing Following Contusion Through Macrophage Polarization

Skeletal muscle contusion is among the most common injuries in traumatology and clinics of sports medicine. The injured muscle is vulnerable to re-injury owing to fibrosis formation. Given that the bone marrow stromal cell-derived exosomes (BMSC-Exos) displayed promising therapeutic effect for various tissues, we used BMSC-Exos to treat skeletal muscle contusion and investigated its effects on muscle healing. In this study, the in vivo model of skeletal muscle contusion was established by subjecting the tibialis anterior of young male mice to hit injury, and the in vitro inflammation model was established by lipopolysaccharide treatment on macrophages. Macrophage depletion model was built by intraperitoneal injection with clodronate-containing liposomes. Exosomes were isolated and purified from the supernatant of BMSCs using gradient centrifugation. Nanoparticle tracking analysis, transmission electron microscope, and western blot were used to identify the exosomes. HE stain, Masson stain, immunofluorescence, and biomechanical testing were carried out on the muscle tissue. In addition, enzyme-linked immunosorbent assay (ELISA) assays, real-time qPCR, flow cytometry, and PKH67 fluorescence trace were conducted in vitro. Intramuscular injection of BMSC-Exos to mice after muscle contusion alleviated inflammation level, reduced fibrosis size, promoted muscle regeneration, and improved biomechanical property. After macrophages depletion, the effects of BMSC-Exos were inhibited. In vitro, PKH-67 fluorescence was internalized into macrophages. BMSC-Exos promoted M2 macrophages polarization both in vivo and in vitro. At the same time, BMSC-Exos reduced the production of inflammatory cytokines under the inflammatory microenvironment and upregulated anti-inflammatory factors expression. In conclusion, BMSC-Exos attenuated muscle contusion injury and promoted muscle healing in mice by modifying the polarization status of macrophages and suppressing the inflammatory reaction.

Accelerated Muscle Recovery After In Vivo Curcumin Supplementation

The currently available treatment options for muscle injuries are suboptimal and often delay muscle recovery. In this study, the effects of curcumin on inflammation and skeletal muscle regeneration after contusion-induced injury in mice were investigated. The mice were randomly assigned to 4 groups, namely normal control (NC), with induced injury (mass-drop injury, MDI) and without treatment (MDI [M]), with induced injury and diclofenac (DCF) treatment (MDI + DCF [M + D]), and with induced injury and curcumin treatment (MDI + curcumin [M + C]). Contusion-induced injury was inflicted on the left gastrocnemius muscle, and DCF or curcumin was orally administered after injury once per day for 7 days. The M group exhibited significantly higher lipid peroxidation, myeloperoxidase (MPO), and desmin than the NC group. The M + D and M + C groups have lower lipid peroxidation and neutrophils (decrease in MPO protein) and higher muscle satellite cell regeneration (increase in desmin protein) than the M group. Additionally, for the contusion-induced muscle injury, curcumin could affect the specific proteins of inflammation, neutrophils, and differentiation of satellite cells, including Ikk-α/ß, MPO, and myogenin. In conclusion, curcumin potentially accelerates muscle recovery; therefore, it may be a potential candidate for further research as an effective treatment to enhance muscle repair.

Prosopis Plant Chemical Composition and Pharmacological Attributes: Targeting Clinical Studies from Preclinical Evidence

Members of the Prosopis genus are native to America, Africa and Asia, and have long been used in traditional medicine. The Prosopis species most commonly used for medicinal purposes are P. africana, P. alba, P. cineraria, P. farcta, P. glandulosa, P. juliflora, P. nigra, P. ruscifolia and P. spicigera, which are highly effective in asthma, birth/postpartum pains, callouses, conjunctivitis, diabetes, diarrhea, expectorant, fever, flu, lactation, liver infection, malaria, otitis, pains, pediculosis, rheumatism, scabies, skin inflammations, spasm, stomach ache, bladder and pancreas stone removal. Flour, syrup, and beverages from Prosopis pods have also been potentially used for foods and food supplement formulation in many regions of the world. In addition, various in vitro and in vivo studies have revealed interesting antiplasmodial, antipyretic, anti-inflammatory, antimicrobial, anticancer, antidiabetic and wound healing effects. The phytochemical composition of Prosopis plants, namely their content of C-glycosyl flavones (such as schaftoside, isoschaftoside, vicenin II, vitexin and isovitexin) has been increasingly correlated with the observed biological effects. Thus, given the literature reports, Prosopis plants have positive impact on the human diet and general health. In this sense, the present review provides an in-depth overview of the literature data regarding Prosopis plants' chemical composition, pharmacological and food applications, covering from pre-clinical data to upcoming clinical studies.

Non-invasive Assessment of Changes in Muscle Injury by Ultrasound Shear Wave Elastography: An Experimental Study in Contusion Model

The present study investigated the potential of ultrasound shear wave elastography (SWE) in assessment of muscle stiffness in muscle injury. SWE was performed on the injured muscle in 30 New Zealand rabbits that were randomly assigned to three groups: the contusion group, which was not treated with an efficient therapeutic strategy after muscle injury; the treatment group, which was treated with a therapeutic scheme after muscle injury; and the healthy group, which was not injured and served as a control. Both the mean Young's modulus (E_mean) and the maximum Young's modulus (E_max) were obtained pre-injury and 0.5, 1, 3, 5, 7, 14 and 28 d post-injury. At these time points, a rabbit in each group was randomly selected for biopsy for histopathological observation as well as comparison with Young's modulus. Eventually, all muscle tissues were collected for histologic analysis of collagen fiber formation. The contusion group had the highest Young's modulus, followed by the treatment group and then the healthy group (p < 0.05). In both the contusion and treatment groups, E_mean and E_max gradually increased within 1-3 d after injury, followed by a gradual decrease. Compared with the healthy group, histopathologic analysis of the contusion and treatment groups revealed the myofibril destruction process, inflammatory reaction and myofibril regeneration. The amount of collagen fibers in the contusion group was maximal compared with the treated and healthy groups (p = 0.001 and p < 0.001, respectively). There were more collagen fibers in the treatment group than in the healthy group (p = 0.003). The abundance of collagen fibers was positively correlated with the value of Young's modulus (E_mean: r = 0.706, p < 0.001; E_max: r = 0.761, p < 0.001). Thus, SWE can be used to detect pathologic changes in injured muscle and to monitor therapeutic effects.

Natural Antioxidants as Potential Therapy, and a Promising Role for Melatonin Against Pulmonary Hypertension

Plasma and serum samples, and lung/heart tissue of pulmonary hypertension (PH) patients and animal models of PH display elevated oxidative stress. Moreover, the severity of PH and levels of oxidative stress increase concurrently, which suggests that oxidative stress could be utilized as a biomarker for PH progression. Accumulating evidence has well established that oxidative stress is also key role player in the development of PH. Preclinical studies have demonstrated that natural antioxidants improved PH condition, and, therefore, antioxidant therapy has been proposed as a potential therapeutic strategy against PH. These natural antioxidants include medicinal plant extracts and compounds such as resveratrol and melatonin. Recent studies suggest that melatonin provides health benefit against PH, by enhancing antioxidant capacity, increasing vasodilation, counteracting lung and cardiac fibrosis, and stunting right ventricular (RV) hypertrophy/failure. This chapter comprehensively reviews and discusses a variety of natural antioxidants and their efficacy in modulating experimental PH. This chapter also demonstrates that antioxidant therapy remains a therapeutic strategy for PH, and particularly identifies melatonin as a safe, cost-effective, and promising antioxidant therapy.

Effects of dextrose prolotherapy on contusion-induced muscle injuries in mice

Current treatment options for muscle injuries remain suboptimal and often result in delayed/incomplete recovery of damaged muscles. In this study, the effects of dextrose prolotherapy on inflammation and regeneration of skeletal muscles after a contusion injury were investigated. Mice were separated into five groups, including a normal control (NC), post-injury with no treatment (mass-drop injury, MDI), post-injury with 10% dextrose (MDI + 10% dextrose), post-injury with 20% dextrose (MDI + 20% dextrose), and post-injury with 30% dextrose (MDI + 30% dextrose). The gastrocnemius muscles of the mice were subjected to an MDI, and muscle samples were collected at 7 days post-injury. Results showed the serum creatine kinase (CK), blood urea nitrogen (BUN), creatinine (CREA), and low-density lipoprotein (LDH) of the MDI-alone group were significantly higher than those of the normal control group (p<0.05). However, levels of serum CK, BUN, CREA, and lactate dehydrogenase (LDH) significantly decreased with different concentrations of dextrose. In addition, dextrose suppressed the macrophage response (F4/80 protein decreased) and promoted muscle satellite cell regeneration (desmin protein increased). In conclusion, dextrose prolotherapy can effectively help repair muscles; therefore, it may be one of the methods for clinically treating muscle injuries.