Impact of Human Recombinant Irisin on Tissue-Engineered Skeletal Muscle Structure and Function.

Tissue engineering of exogenous skeletal muscle units (SMUs) through isolation of muscle satellite cells from muscle biopsies is a potential treatment method for acute volumetric muscle loss (VML). A current issue with this treatment process is the limited capacity for muscle stem cell (satellite cell) expansion in cell culture, resulting in a decreased ability to obtain enough cells to fabricate SMUs of appropriate size and structural quality and that produce native levels of contractile force. This study determined the impact of human recombinant irisin on the growth and development of three-dimensional (3D) engineered skeletal muscle. Muscle satellite cells were cultured without irisin (control) or with 50, 100, or 250 ng/mL of irisin supplementation. Light microscopy was used to analyze myotube formation with particular focus placed on the diameter and density of the monotubes during growth of the 3D SMU. Following the formation of 3D constructs, SMUs underwent measurement of maximum tetanic force to analyze contractile function, as well as immunohistochemical staining, to characterize muscle structure. The results indicate that irisin supplementation with 250 ng/mL significantly increased the average diameter of myotubes and increased the proliferation and differentiation of myoblasts in culture but did not have a consistent significant impact on force production. In conclusion, supplementation with 250 ng/mL of human recombinant irisin promotes the proliferation and differentiation of myotubes and has the potential for impacting contractile force production in scaffold-free tissue-engineered skeletal muscle.

Repairing Volumetric Muscle Loss with Commercially Available Hydrogels in an Ovine Model.

Volumetric muscle loss (VML) is the loss of skeletal muscle that exceeds the muscle's self-repair mechanism and leads to permanent functional deficits. In a previous study, we demonstrated the ability of our scaffold-free, multiphasic, tissue-engineered skeletal muscle units (SMUs) to restore muscle mass and force production. However, it was observed that the full recovery of muscle structure was inhibited due to increased fibrosis in the repair site. As such, novel biomaterials such as hydrogels (HGs) may have significant potential for decreasing the acute inflammation and subsequent fibrosis, as well as enhancing skeletal muscle regeneration following VML injury and repair. The goal of the current study was to assess the biocompatibility of commercially available poly(ethylene glycol), methacrylated gelatin, and hyaluronic acid (HA) HGs in combination with our SMUs to treat VML in a clinically relevant large animal model. An acute 30% VML injury created in the sheep peroneus tertius (PT) muscle was repaired with or without HGs and assessed for acute inflammation (incision swelling) and white blood cell counts in blood for 7 days. At the 7-day time point, HA was selected as the HG to use for the combined HG/SMU repair, as it exhibited a reduced inflammation response compared to the other HGs. Six weeks after implantation, all groups were assessed for gross and histological structural recovery. The results showed that the groups repaired with an SMU (SMU-Only and SMU+HA) restored muscle mass to greater degree than the groups with only HG and that the SMU groups had PT muscle masses that were statistically indistinguishable from its uninjured contralateral PT muscle. Furthermore, the HA HG, SMU-Only, and SMU+HA groups displayed notable efficacy in diminishing pro-inflammatory markers and showed an increased number of regenerating muscle fibers in the repair site. Taken together, the data demonstrates the efficacy of HA HG in decreasing acute inflammation and fibrotic response. The combination of HA and our SMUs also holds promise to decrease acute inflammation and fibrosis and increase muscle regeneration, advancing this combination therapy toward clinically relevant interventions for VML injuries in humans.

Engineered Tissue Graft for Repair of Injured Infraspinatus Rotator Cuff Tendon.

Rotator cuff tears constitute a vast majority of shoulder-related injuries, occurring in a wide population range and increasing in incidence with age. Current treatments for full thickness tears use suture to secure the ruptured tendon back to its native attachment site and often retear due to improper enthesis regeneration. To reduce the occurrence of retear, our laboratory developed an engineered tendon graft for rotator cuff repair (ETG-RC) to serve as an underlayment to traditional suture repair. We hypothesize the ETG-RC will aid in the repair of the torn rotator cuff tendon by promoting the regeneration of a functional enthesis. This devitalized graft fabricated from ovine-derived bone marrow stromal cells was evaluated for biomechanical and histomorphology properties in an ovine infraspinatus rotator cuff repair model. Compared with a current standard practice Suture-Only model, the ETG-RC repair showed comparable high strain-to-failure forces, greater fibrocartilage deposition, regeneration of zonal gradients, and Shapey's fibers formation, indicative of enthesis regeneration. Enthesis regeneration after rotator cuff repair should repair mechanical properties and alleviate the need for subsequent surgeries required due to retear. The ETG-RC could potentially be used for repairing other tendon injuries throughout the body.

Simulation-Based System Analysis: Testing Preparedness for Extracorporeal Membrane Oxygenation Cannulation in Pediatric COVID-19 Patients.

INTRODUCTION: Coronavirus Disease-2019 presents risk to both patients and medical teams. Staff-intensive, complex procedures such as extracorporeal membrane oxygenation (ECMO) or extracorporeal cardiopulmonary resuscitation (eCPR) may increase chances of exposure and spread. This investigation aimed to rapidly deploy an in situ Simulation-based Clinical Systems Testing (SbCST) framework to identify Latent Safety Threats (LSTs) related to ECMO/eCPR initiation during a pandemic. METHODS: The adapted SbCST framework tested systems related to ECMO/eCPR initiation in the Neonatal and Pediatric Intensive Care Units. Systems were evaluated in six domains (Resources, Processes/Systems, Facilities, Clinical Performance, Infection Control, and Communication). We conducted three high-fidelity simulations with members from the Neonatal Intensive Care Unit General Surgery, Pediatric Intensive Care Unit Cardiovascular Surgery (CV), and Pediatric Intensive Care Unit General Surgery teams. Content experts evaluated systems issues during simulation, and LSTs were identified during debriefing. Data were analyzed for frequency of LSTs and trends in process gaps. RESULTS: Sixty-six LSTs were identified across three scenarios. Resource issues comprised the largest category (26%), followed by Process/System issues (24%), Infection Control issues (24%), Communication issues (17%), and Facility and Clinical Performance issues (5% each). LSTs informed new team strategies such as the use of a "door/PPE monitor" and "inside/outside" team configuration. CONCLUSIONS: The adapted SbCST framework identified multiple LSTs related to ECMO/eCPR cannulation and infection control guidelines in the setting of Coronavirus Disease-2019. Through SbCSTs, we developed guidelines to conserve PPE and develop optimal workflows to reduce patient/staff exposure in a high-risk procedure. This project may guide other hospitals to adapt SbCSTs strategies to test/adjust rapidly changing guidelines.

A tissue engineering approach for repairing craniofacial volumetric muscle loss in a sheep following a 2, 4, and 6-month recovery.

Volumetric muscle loss (VML) is the loss of skeletal muscle that results in significant and persistent impairment of function. The unique characteristics of craniofacial muscle compared trunk and limb skeletal muscle, including differences in gene expression, satellite cell phenotype, and regenerative capacity, suggest that VML injuries may affect craniofacial muscle more severely. However, despite these notable differences, there are currently no animal models of craniofacial VML. In a previous sheep hindlimb VML study, we showed that our lab's tissue engineered skeletal muscle units (SMUs) were able to restore muscle force production to a level that was statistically indistinguishable from the uninjured contralateral muscle. Thus, the goals of this study were to: 1) develop a model of craniofacial VML in a large animal model and 2) to evaluate the efficacy of our SMUs in repairing a 30% VML in the ovine zygomaticus major muscle. Overall, there was no significant difference in functional recovery between the SMU-treated group and the unrepaired control. Despite the use of the same injury and repair model used in our previous study, results showed differences in pathophysiology between craniofacial and hindlimb VML. Specifically, the craniofacial model was affected by concomitant denervation and ischemia injuries that were not exhibited in the hindlimb model. While clinically realistic, the additional ischemia and denervation likely created an injury that was too severe for our SMUs to repair. This study highlights the importance of balancing the use of a clinically realistic model while also maintaining control over variables related to the severity of the injury. These variables include the volume of muscle removed, the location of the VML injury, and the geometry of the injury, as these affect both the muscle's ability to self-regenerate as well as the probability of success of the treatment.

Simulation in Pediatric Emergency Medicine Fellowships.

BACKGROUND AND OBJECTIVES: Graduate medical education faces challenges as programs transition to the next accreditation system. Evidence supports the effectiveness of simulation for training and assessment. This study aims to describe the current use of simulation and barriers to its implementation in pediatric emergency medicine (PEM) fellowship programs. METHODS: A survey was developed by consensus methods and distributed to PEM program directors via an anonymous online survey. RESULTS: Sixty-nine (95%) fellowship programs responded. Simulation-based training is provided by 97% of PEM fellowship programs; the remainder plan to within 2 years. Thirty-seven percent incorporate >20 simulation hours per year. Barriers include the following: lack of faculty time (49%) and faculty simulation experience (39%); limited support for learner attendance (35%); and lack of established curricula (32%). Of those with written simulation curricula, most focus on resuscitation (71%), procedures (63%), and teamwork/communication (38%). Thirty-seven percent use simulation to evaluate procedural competency and resuscitation management. PEM fellows use simulation to teach (77%) and have conducted simulation-based research (33%). Thirty percent participate in a fellows' "boot camp"; however, finances (27%) and availability (15%) limit attendance. Programs receive simulation funding from hospitals (47%), academic institutions (22%), and PEM revenue (17%), with 22% reporting no direct simulation funding. CONCLUSIONS: PEM fellowships have rapidly integrated simulation into their curricula over the past 5 years. Current limitations primarily involve faculty and funding, with equipment and dedicated space less significant than previously reported. Shared curricula and assessment tools, increased faculty and financial support, and regionalization could ameliorate barriers to incorporating simulation into PEM fellowships.

A randomized clinical trial of oral transmucosal fentanyl citrate versus intravenous morphine sulfate for initial control of pain in children with extremity injuries.

BACKGROUND: Extremity injury is a common condition that requires pain management in an emergency department. In pediatric patients, the most frequently used method of pain control is intravenous (IV) morphine sulfate. Oral transmucosal fentanyl citrate (OTFC) is a potential alternative to morphine, which may obviate the need to place an IV before addressing pain. OBJECTIVE: To compare OTFC with IV morphine for sedation and analgesia during initial evaluation of children with deformity of an extremity and suspected fracture. DESIGN/METHODS: A randomized controlled trial of OTFC versus IV morphine in which 8- to 18-year-olds presenting to pediatric tertiary care emergency department with extremity deformity and suspected fracture were eligible. Only those with visual analog scale (VAS) (0 = no pain, 100 = worst pain imaginable) score equal to or greater than 50/100, and American Society of Anesthesia I or II qualified. Patients were excluded if history of loss of/altered level of consciousness, multiple traumatic injuries, or if patient had received prior medication for pain control. All patients enrolled were randomly assigned to receive either IV morphine (0.1 mg/kg) or OTFC (10-15 mug/kg). Patients rated pain intensity using VAS; scores were recorded before medicating and at 15-minute intervals after the medication was given. Adverse events such as emesis, pruritus, and respiratory depression were recorded. RESULTS: A total of 87 patients were enrolled in study (OTFC, 47; morphine, 40). There are no significant differences between the 2 groups when comparing sex, age, weight, and pretreatment VAS score (P > 0.05). Although the VAS scores were not significantly different before medicating the patient, an analysis of variance shows that there was a significant difference (P > 0.05) in VAS scores at 30 minutes. The differences persisted for every 15 minutes through the 75 minutes of monitoring. There was no statistically significant difference between the 2 groups when comparing the number of adverse events (P = 0.23). CONCLUSIONS: The use of OTFC can provide improved pain control when compared with IV morphine. The pain reduction starts 30 minutes after initiation of medication, and the effect is seen as far as 75 minutes after the initiation of analgesic medication. The study size was too small to make any statements concerning adverse effects; thus, further studies with larger sample sizes are needed to determine the use of OTFC.

Evaluation of a curriculum for intimate partner violence screening in a pediatric emergency department.

OBJECTIVE: We sought to describe the assessment of course participant changes in attitudes, self-efficacy, and behaviors after completion of the Its Time to Ask training curriculum for screening for intimate partner violence (IPV) in a pediatric emergency department (PED). METHODS: A 22-item Likert scale questionnaire was administered at baseline (before training), after training, and at 6-month follow-up to PED employee participants in a 2-hour IPV education program. Mean participant responses were compared between baseline/posttraining and baseline/6-month follow-up. Participants also completed a course-satisfaction survey. RESULTS: A total of 79 PED staff completed the baseline questionnaire before the training. Eighty-seven participants completed the posttraining questionnaire, and 48 completed the 6-month follow-up questionnaire. Participants had consistent, positive changes in attitudes after training that persisted at the 6-month follow-up for 5 items on the questionnaire. Attitudes that did not change showed baseline means already in disagreement with questionnaire statements. Participants reported significant, positive changes for all 7 self-efficacy statements at 1 or both of the posttraining evaluations. The only changes in behavior were observed at 6 months. The majority of participants were satisfied with the training and would recommend it to colleagues. CONCLUSIONS: Significant, self-reported changes in attitudes, self-efficacy, and behaviors/clinical practice regarding screening for IPV in a PED can be achieved through participation in a brief training curriculum.