Guidelines for the acute care of severe limb trauma patients

Embryonic stem cell-derived mesenchymal stem cells alleviate skeletal muscle injury induced by acute compartment syndrome

Background

Acute compartment syndrome (ACS), a well-known complication of musculoskeletal injury, results in muscle necrosis and cell death. Embryonic stem cell-derived mesenchymal stem cells (ESC-MSCs) have been shown to be a promising therapy for ACS. However, their effectiveness and potentially protective mechanism remain unknown. The present study was designed to investigate the efficacy and underlying mechanism of ESC-MSCs in ACS-induced skeletal muscle injury.

Method

A total of 168 male Sprague–Dawley (SD) rats underwent 2 h of intracompartmental pressure elevation by saline infusion into the anterior compartment of the left hindlimb to establish the ACS model. ESC-MSCs were differentiated from the human embryonic stem cell (ESC) line H9. A dose of 1.2 × 10⁶ of ESC-MSCs was intravenously injected during fasciotomy. Post-ACS assessments included skeletal edema index, serum indicators, histological analysis, apoptosis, fibrosis, regeneration, and functional recovery of skeletal muscle. Then, fluorescence microscopy was used to observe the distribution of labeled ESC-MSCs in vivo, and western blotting and immunofluorescence analyses were performed to examine macrophages infiltration in skeletal muscle. Finally, we used liposomal clodronate to deplete macrophages and reassess skeletal muscle injury in response to ESC-MSC therapy.

Result

ESC-MSCs significantly reduced systemic inflammatory responses, ACS-induced skeletal muscle edema, and cell apoptosis. In addition, ESC-MSCs inhibited skeletal muscle fibrosis and increased regeneration and functional recovery of skeletal muscle after ACS. The beneficial effects of ESC-MSCs on ACS-induced skeletal muscle injury were accompanied by a decrease in CD86-positive M1 macrophage polarization and an increase in CD206-positive M2 macrophage polarization. After depleting macrophages with liposomal clodronate, the beneficial effects of ESC-MSCs were attenuated.

Conclusion

Our findings suggest that embryonic stem cell-derived mesenchymal stem cells infusion could effectively alleviate ACS-induced skeletal muscle injury, in which the beneficial effects were related to the regulation of macrophages polarization.

[Bleeding management in the operating theatre]

Despite all the measures taken preoperatively, bleeding may persist and require surgical control. Before considering treatment, it is necessary to establish the diagnosis with the origin of the bleeding. The surgical procedure depends on the aetiology. There are many surgical options and adjuvant measures to consider. They should be known by the operating theatre nurse, who is a major player in surgical management. Successful control of bleeding requires quality multidisciplinary collaboration.

[The ABC's of the tactical tourniquet]

Uncontrolled bleeding is the leading cause of preventable death. After rapid diagnosis of the injury, early stoppage of the bleeding and maintenance of effective coagulation are, in the pre-hospital setting, the two mainstays of treatment of hemorrhagic shock. The latter requires a trained and experienced medical and paramedical team to prevent patient morbidity and mortality.