In vitro myotoxic effects of bupivacaine on rhabdomyosarcoma cells, immortalized and primary muscle cells

Ascorbic acid reduces Ropivacaine-induced myotoxicity in cultured human osteoporotic skeletal muscle cells

BACKGROUND

Osteoporosis is a worldwide health issue. Loss of bone mass is a potential risk factor for fragility fractures, and osteoporotic fractures place a considerable burden on society. Bone and muscle represent a functional unit in which the two tissues are intimately interconnected. Ropivacaine is a potent local anesthetic used in clinical practice for intraoperative anesthesia and postoperative pain management, in particular for hip surgery. When injected, Ropivacaine can diffuse locally through, in particular in surrounding skeletal muscle tissue, causing dose-dependent cytotoxicity, oxidative stress and myogenesis impairment. Based on those evidences, we focused our attention on Ropivacaine-induced cytotoxicity on cultured human myoblasts.

METHODS

Primary human myoblasts and myotubes from healthy subjects, osteoarthritic and osteoporotic patients (OP) were cultured in the presence of Ropivacaine. In some experiments, ascorbic acid (AsA) was added as a potent antioxidant agent. Cell viability and ROS levels were evaluated to investigate the myotoxic activity and Real-Time PCR and Western blot analysis carried out to investigate the expression of proliferation and myogenic markers.

RESULTS

A dose-dependent decrease of cell viability was observed after Ropivacaine exposure in both OP myoblasts and myotubes cultures, whereas those effects were not observed in the presence of Propofol, a general anesthetic. The adding of AsA reduced Ropivacaine negative effects in OP myoblast cultures. In addition, Ropivacaine exposure also increased ROS levels and upregulated Nox4 expression, an enzyme primarily implicated in skeletal muscle ROS generation. AsA treatment counteracted the oxidant activity of Ropivacaine and partially restored the basal condition in cultures. Positive myogenic markers, such as MyoD and Myf5, were downregulated by Ropivacaine exposure, whereas myostatin, a negative regulator of muscle growth and differentiation, was upregulated. The phenotypic deregulation of myogenic controllers in the presence of Ropivacaine was counteracted by AsA treatment.

CONCLUSIONS

Our findings highlight the oxidative stress-mediated myotoxic effect of Ropivacaine on human skeletal muscle tissue cell cultures, and suggest treatment with AsA as valid strategy to mitigate its negative effects and allowing an ameliorated functional skeletal muscle recovery in patients undergoing hip replacement surgery for osteoporotic bone fracture.

Cytotoxicity of Local Anesthetics on Bone, Joint, and Muscle Tissues: A Narrative Review of the Current Literature

Background

Local anesthetics are commonly used in surgical procedures to control pain in patients. Whilst the cardiotoxicity and neurotoxicity of local anesthetics have received much attention, the cytotoxicity they exert against bone, joint, and muscle tissues has yet to be well recognized.

Objective

This review aimed to raise awareness regarding how local anesthetics may cause tissue damage and provide a deeper understanding of the mechanisms of local anesthetic-induced cytotoxicity. We summarized the latest progress on the cytotoxicity of local anesthetics and the underlying mechanisms and discussed potential strategies to reduce it.

Findings

We found that the toxic effects of local anesthetics on bone, joint, and muscle tissues were time- and concentration-dependent in vitro. Local anesthetics induced apoptosis, necrosis, and autophagy through specific cellular pathways. Altogether, this review indicates that toxicity of local anesthetics may be avoided by rationally selecting the appropriate anesthetic, limiting the total amount, and determining the lowest effective concentration and duration.

Effect of species, concentration and volume of local anesthetics on intervertebral disk degeneration in rats with discoblock

PURPOSE

Discoblock is effective in relieving discogenic low back pain, but it can also cause intervertebral disk degeneration (IDD). The effect of species, concentration and volume of local anesthetics on IDD with discoblock have not been reported. The purpose was to study the effect of species, concentration and volume of local anesthetics on IDD in rats undergoing discoblock.

METHODS

The effects of local anesthetics on nucleus pulposus cell (NPC) viability in vitro were studied. NPCs were exposed to lidocaine, bupivacaine and ropivacaine at different concentrations. NPC viability was measured. The least cytotoxic local anesthetic was used in vivo. The concentration and volume of local anesthetics on IDD in rat with discoblocks were tested in vivo. Detection indicators included X-ray, MRI, water content of the disk and histological changes.

RESULTS

The toxicity of local anesthetics to NPCs was dose and time dependent, and the cytotoxicity of different local anesthetics was different. Among the three local anesthetics, ropivacaine was the least toxic to NPCs. The effect of ropivacaine concentration on IDD was not significant, as detected by X-ray, MRI, disk water content and histology (P < 0.05). The volume of ropivacaine has a significant effect on IDD, as supported by X-ray, MRI, disk water content and histology (P < 0.05). Acupuncture itself significantly increased IDD, as detected by MRI, disk water content and histology (P < 0.05).

CONCLUSION

Ropivacaine should be selected for its low cytotoxicity. A lower volume and slow injection speed should be used to reduce IDD during discoblock.

Bupivacaine modulates the apoptosis and ferroptosis in bladder cancer via phosphatidylinositol 3-kinase (PI3K)/AKT pathway

The study aimed to explore the effects of local anesthetic bupivacaine on bladder cancer cells in vivo and in vitro. The cytotoxicity was detected by MTT assay. Apoptosis was measured by Hoechst 33342 staining and TUNEL. The contents of Fe²⁺, Malondialdehyde (MDA), Glutathione (GSH) and reactive oxygen species (ROS) were evaluated by the corresponding kit. Mitochondrial membrane potential was assessed by JC-1 kit. HE staining, TUNEL and immunohistochemistry were used to detect the xenografted tumors. Protein expression was estimated by Western blot. Bupivacaine significantly inhibited the activity of T24 cells and 5637 cells at 0.25-16 mM. Bupivacaine promoted cell apoptosis with increased concentration. bupivacaine inhibited the expression of Bcl-2 and increased the expression of Bax and cytochrome C. Moreover, bupivacaine amplified the level of Fe²⁺ and ROS, and restrained the expression of cystine/glutamic acid reverse transporter (xCT) and glutathione peroxidase 4 (GPX4). Further results showed that bupivacaine decreased mitochondrial membrane potential, reduced GSH, and increased MDA levels. Besides, bupivacaine attenuated the phosphorylation of PI3K, Akt, and mTOR. In addition, bupivacaine suppressed the growth of xenografted tumors, induced apoptosis and ferroptosis, and inhibited the activity of PI3K/AKT signaling pathway in xenografted tumors. Bupivacaine could induce apoptosis and ferroptosis by inhibiting PI3K/Akt signaling pathway in bladder cancer cells.

Peptoids with Antibiofilm Activity against the Gram Negative Obligate Anaerobe, Fusobacterium nucleatum

Peptoids (oligo N-substituted glycines) are peptide analogues, which can be designed to mimic host antimicrobial peptides, with the advantage that they are resistant to proteolytic degradation. Few studies on the antimicrobial efficacy of peptoids have focused on Gram negative anaerobic microbes associated with clinical infections, which are commonly recalcitrant to antibiotic treatment. We therefore studied the cytotoxicity and antibiofilm activity of a family of peptoids against the Gram negative obligate anaerobe Fusobacterium nucleatum, which is associated with infections in the oral cavity. Two peptoids, peptoid 4 (NaeNpheNphe)4 and peptoid 9 (NahNspeNspe)3 were shown to be efficacious against F. nucleatum biofilms at a concentration of 1 μM. At this concentration, peptoids 4 and 9 were not cytotoxic to human erythrocytes or primary human gingival fibroblast cells. Peptoids 4 and 9 therefore have merit as future therapeutics for the treatment of oral infections.

Potential Impact of Local Anesthetics Inducing Granulocyte Arrest and Altering Immune Functions on Perioperative Outcome

Introduction

Local anesthetics (LAs) are frequently used during anesthesia; however, they may influence granulocyte function which in turn could modify immune responses in the perioperative period. Therefore, the aim of this study was to investigate the impact of clinically used doses of bupivacaine and lidocaine on granulocyte function with regard to migration, reactive oxygen species (ROS) production, neutrophil extracellular traps (NETosis) formation, and viability.

Methods

A total of 38 granulocyte-enriched samples from healthy subjects were obtained by whole blood lysis. Polymorphonuclear neutrophil (PMN) samples were incubated simultaneously with different concentrations of either bupivacaine (0.03–3.16 mmol/L) or lidocaine (0.007–14.21 mmol/L), or without drug (control). Live cell imaging was conducted in order to observe granulocyte chemotaxis, migration, ROS production, and NETosis. Flow cytometry was used to analyze viability and antigen expression.

Results

The track length (TL) of PMNs exposed to bupivacaine concentrations of 0.16 mmol/L and above significantly decreased compared to the control. Low concentrations of lidocaine were associated with slight but significant increases in TL, whereas this changed with concentrations above 1.4 mmol/L, showing a significant decrease in TL. PMN incubated with bupivacaine concentrations of 1.58 mmol/L and above or lidocaine concentrations of at least 3.6 mmol/L showed no migration or chemotaxis at all. Time to onset of maximal ROS production and time for half-maximal NETosis decreased in a dose-dependent manner for both substances. Equipotency in NETosis induction was reached by bupivacaine (1.1 mmol/L) at significantly lower concentrations than lidocaine (7.96 mmol/L). Cell viability and oxidative burst were unaffected by LAs.

Conclusion

Local anesthetics in clinically used doses ameliorate granulocyte defense mechanisms, thus indicating their potentially decisive effect during the perioperative period.

Alginate encapsulation for bupivacaine delivery and mesenchymal stromal cell immunomodulatory cotherapy

PURPOSE

Mesenchymal stromal cells (MSCs) are used to treat various inflammatory conditions. In parallel, to mitigate pain associated with inflammation, analgesics or opioids are prescribed, often with significant side effects. Local anesthetics (LAs) offer a promising alternative to these medications. However, their short duration and negative effects on anti-inflammatory MSCs have limited their therapeutic effectiveness. To mitigate these negative effects and to move toward developing a cotherapy, we engineered a sustained release bupivacaine alginate-liposomal construct that enables up to 4 days of LA release. By encapsulating MSC in alginate (eMSC), we demonstrate that we can further increase drug concentration to clinically relevant levels, without compromising eMSC viability or anti-inflammatory function.

MATERIALS AND METHODS

MSCs were freely cultured or encapsulated in alginate microspheres ± TNFα/IFN-γ and were left untreated or dosed with bolus, liposomal, or construct bupivacaine. After 24, 48, and 96 hours, the profiles were assessed to quantify secretory function associated with LA-MSC interactions. To approximate LA exposure over time, a MATLAB model was generated.

RESULTS

eMSCs secrete similar levels of IL-6 and prostaglandin E2 (PGE2) regardless of LA modality, whereas free MSCs secrete larger amounts of IL-6 and lower amounts of anti-inflammatory PGE2. Modeling the system indicated that higher doses of LA can be used in conjunction with eMSC while retaining eMSC viability and function. In general, eMSC treated with higher doses of LA secreted similar or higher levels of immunomodulatory cytokines.

CONCLUSION

eMSCs, but not free MSC, are protected from LA, regardless of LA modality. Increasing the LA concentration may promote longer and stronger pain mitigation while the protected eMSCs secrete similar, if not higher, immunomodulatory cytokine levels. Therefore, we have developed an approach, using eMSC and the LA construct that can potentially be used to reduce pain as well as improve MSC anti-inflammatory function.

Nonoperative treatment of muscle injuries - recommendations from the GOTS expert meeting

BACKGROUND

Muscle injuries are some of the most common injuries in sports; they have a high recurrence rate and can result in the loss of ability to participate in training or competition. In clinical practice, a wide variety of treatment strategies are commonly applied. However, a limited amount of evidence-based data exists, and most therapeutic approaches are solely based on "best practice". Thus, there is a need for consensus to provide strategies and recommendations for the treatment of muscle injuries.

METHODS

The 2016 GOTS Expert Meeting, initiated by the German-Austrian-Swiss Society for Orthopaedic Traumatologic Sports Medicine (GOTS), focused on the topic of muscle and tendon injuries and was held in Spreewald/Berlin, Germany. The committee was composed of twenty-two medical specialists. Nine of them were delegated to a subcommittee focusing on the nonoperative treatment of muscle injuries. The recommendations and statements that were developed were reviewed by the entire consensus committee and voted on by the members.

RESULTS

The committee reached a consensus on the utility and effectiveness of the management of muscle injuries.

MAIN RESULTS

the "PRICE" principle to target the first inflammatory response is one of the most relevant steps in the treatment of muscle injuries. Haematoma aspiration may be considered in the early stages after injury. There is presently no clear evidence that intramuscular injections are of use in the treatment of muscle injuries. The ingestion of non-steroidal anti-inflammatory drugs (NSAIDs) should be regarded critically because there is currently no hard evidence to support their use, although they are appropriate in exceptional cases.

CONCLUSIONS

The present work provides a structured overview of the various nonoperative treatment strategies of muscle injuries and evaluates their effectiveness with respect to the existing scientific evidence and clinical expertise in the context of basic science on the healing process of muscle injuries. The committee agreed that there is a compelling need for further studies, including high-quality randomized investigations to completely evaluate the effectiveness of the existing therapeutic approaches. The given recommendations may be updated and adjusted as further evidence will be generated.