Lineage-Specific Mesenchymal Stromal Cells Derived from Human iPSCs Showed Distinct Patterns in Transcriptomic Profile and Extracellular Vesicle Production.

Over the past decades, mesenchymal stromal cells (MSCs) have been extensively investigated as a potential therapeutic cell source for the treatment of various disorders. Differentiation of MSCs from human induced pluripotent stem cells (iMSCs) has provided a scalable approach for the biomanufacturing of MSCs and related biological products. Although iMSCs shared typical MSC markers and functions as primary MSCs (pMSCs), there is a lack of lineage specificity in many iMSC differentiation protocols. Here, a stepwise hiPSC-to-iMSC differentiation method is employed via intermediate cell stages of neural crest and cytotrophoblast to generate lineage-specific MSCs with varying differentiation efficiencies and gene expression. Through a comprehensive comparison between early developmental cell types (hiPSCs, neural crest, and cytotrophoblast), two lineage-specific iMSCs, and six source-specific pMSCs, are able to not only distinguish the transcriptomic differences between MSCs and early developmental cells, but also determine the transcriptomic similarities of iMSC subtypes to postnatal or perinatal pMSCs. Additionally, it is demonstrated that different iMSC subtypes and priming conditions affected EV production, exosomal protein expression, and cytokine cargo.

INDUCED PLURIPOTENT STEM CELL-DERIVED MESENCHYMAL STEM CELLS-DERIVED EXTRACELLULAR VESICLES ATTENUATE LPS-INDUCED LUNG INJURY AND ENDOTOXEMIA IN MICE.

ABSTRACT: Introduction: We hypothesized extracellular vesicles (EVs) from preconditioned human-induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs) attenuate LPS-induced acute lung injury (ALI) and endotoxemia. Methods: iMSCs were incubated with cell stimulation cocktail (CSC) and EVs were isolated. iMSC-EVs were characterized by size and EV markers. Biodistribution of intratracheal (IT), intravenous, and intraperitoneal injection of iMSC-EVs in mice was examined using IVIS. Uptake of iMSC-EVs in lung tissue, alveolar macrophages, and RAW264.7 cells was also assessed. C57BL/6 mice were treated with IT/IP iMSC-EVs or vehicle ± IT/IP LPS to induce ALI/acute respiratory distress syndrome and endotoxemia. Lung tissues, plasma, and bronchoalveolar lavage fluid (BALF) were harvested at 24 h. Lung histology, BALF neutrophil/macrophage, cytokine levels, and total protein concentration were measured to assess ALI and inflammation. Survival studies were performed using IP LPS in mice for 3 days. Results: iMSC-EV route of administration resulted in differential tissue distribution. iMSC-EVs were taken up by alveolar macrophages in mouse lung and cultured RAW264.7 cells. IT LPS-treated mice demonstrated marked histologic ALI, increased BALF neutrophils/macrophages and protein, and increased BALF and plasma TNF-α/IL-6 levels. These parameters were attenuated by 2 h before or 2 h after treatment with IT iMSC-EVs in ALI mice. Interestingly, the IT LPS-induced increase in IL-10 was augmented by iMSC-EVs. Mice treated with IP LPS showed increases in TNF-α and IL-6 that were downregulated by iMSC-EVs and LPS-induced mortality was ameliorated by iMSC-EVs. Administration of IT iMSC-EVs 2 h after LPS downregulated the increase in proinflammatory cytokines (TNF-α/IL-6) by LPS and further increased IL-10 levels. Conclusions: iMSC-EVs attenuate the inflammatory effects of LPS on cytokine levels in ALI and IP LPS in mice. LPS-induced mortality was improved with administration of iMSC-EVs.

Educational Podcasts: Effect of Content Delivery Timing on Knowledge Acquisition and Retention.

PURPOSE: This study examined whether the order of podcast content influenced knowledge acquisition and retention among emergency medicine (EM) resident physicians. METHOD: This preplanned secondary analysis of 2 large, multicenter trials included a randomized, crossover trial conducted from November 2019 to June 2020 of 100 residents that compared driving and seated condition for two 30-minute podcasts and a randomized, crossover trial conducted from September 2022 to January 2023 of 95 EM residents that compared exercise with seated condition for the same two 30-minute podcasts. Each podcast contained 6 journal article reviews, with the segments recorded in forward or backward order. After completing each podcast, participants completed an initial 20-question test and a 40-question delayed recall test with separate questions. Segments were divided into 3 subgroups based on the order in which they were played (primacy group, recency group, and reference group) for assessment of recency and primacy effects. The mean scaled scores from the primacy and recency groups were compared with scores from the reference group. RESULTS: The study included 195 residents (390 podcasts), with 100 residents listening in the forward order and 95 residents the reverse order. No statistically significant difference was found in immediate recall scores between the primacy and reference groups (d = 0.094; 95% CI, -0.046 to 0.234) or the recency and reference groups (d = -0.041; 95% CI, -0.181 to 0.099) or in 30-day delayed recall score between the primacy and reference groups (d = -0.088; 95% CI, -0.232 to 0.056) or the recency and reference groups (d = -0.083; 95% CI, -0.227 to 0.060). CONCLUSIONS: The order of podcast information did not significantly affect immediate knowledge acquisition or delayed knowledge retention. This finding can inform podcast creators and listeners regarding the order of content when using podcasts for learning.

Differences in Emergency Medicine Resident Procedural Reporting by Gender in the United States.

Background Studies across specialties have demonstrated gender disparities in feedback, learner assessments, and operative cases. However, data are limited on differences in numbers of procedures among residents. Objective To quantify the association between gender and the number of procedures reported among emergency medicine (EM) residents. Methods We conducted a retrospective review of procedural differences by self-identified gender among graduating EM residents at 8 separate programs over a 10-year period (2013 to 2022). Sites were selected to ensure diversity of program length, program type, and geography. Residents from combined training programs, those who did not complete their full training at that institution, and those who did not have data available were excluded. We calculated the mean, SD, median, and IQR for each procedure by gender. We compared reported procedures by gender using linear regression, controlling for institution, and performed a sensitivity analysis excluding outlier residents with procedure totals >3 SD from the mean. Results We collected data from 914 residents, with 880 (96.3%) meeting inclusion criteria. There were 358 (40.7%) women and 522 (59.3%) men. The most common procedures were point-of-care ultrasound, adult medical resuscitation, adult trauma resuscitation, and intubations. After adjusting for institutions, the number of dislocation reductions, chest tube insertions, and sedations were higher for men. The sensitivity analysis findings were stable except for central lines, which were also more common in men. Conclusions In a national sample of EM programs, there were increased numbers of dislocation reductions, chest tube insertions, and sedations reported by men compared with women.

Differences in emergency medicine resident procedural reporting by race and ethnicity.

Background: The recruitment, retention, and training of physicians from groups underrepresented in medicine (UiM) is critically important to the practice of emergency medicine (EM). Studies across specialties have demonstrated disparities in operative experiences among UiM resident learners who are UiM; however, there are limited data on procedural disparities in EM. Objective: We sought to quantify the association between racial and ethnic identities that are UiM and the number of procedures reported among EM residents. Methods: We conducted a retrospective review of procedural differences by UiM status (using self-identified race and ethnicity) among graduating EM residents at nine training programs over a 10-year period. Sites were selected to ensure diversity of program length, program type, and geography. Data from residents in combined training programs, those who did not complete their full training at that institution, and those with missing data or electing not to report race/ethnicity were excluded. We calculated median and interquartile ranges for each procedure by UiM status. We conducted multivariable regression analyses accounting for UiM status, gender, and site as well as a sensitivity analysis excluding values >3 standard deviations from the mean for each procedure. Results: We collected data from 988 total residents, with 718 (73%) being non-UiM, 204 (21%) being UiM, 48 (5%) electing not to specific race/ethnicity, and 18 (2%) missing race/ethnicity data. While unadjusted data demonstrated a difference between UiM and non-UiM resident numbers across several procedures, there were no significant differences in procedures reported after accounting for gender and site in the primary or sensitivity analyses. Conclusions: We did not identify a statistically significant difference in reported procedures between UiM and non-UiM residents in EM. Future work should include qualitative investigations of UiM resident experience surrounding procedures as well as mixed-methods studies to examine how these data interact.

Breaking Down Silos Between Medical Education and Health Systems: Creating an Integrated Multilevel Data Model to Advance the Systems-Based Practice Competency.

ABSTRACT: The complexity of improving health in the United States and the rising call for outcomes-based physician training present unique challenges and opportunities for both graduate medical education (GME) and health systems. GME programs have been particularly challenged to implement systems-based practice (SBP) as a core physician competency and educational outcome. Disparate definitions and educational approaches to SBP, as well as limited understanding of the complex interactions between GME trainees, programs, and their health system settings, contribute to current suboptimal educational outcomes elated to SBP. To advance SBP competence at individual, program, and institutional levels, the authors present the rationale for an integrated multilevel systems approach to assess and evaluate SBP, propose a conceptual multilevel data model that integrates health system and educational SBP performance, and explore the opportunities and challenges of using multilevel data to promote an empirically driven approach to residency education. The development, study, and adoption of multilevel analytic approaches to GME are imperative to the successful operationalization of SBP and thereby imperative to GME's social accountability in meeting societal needs for improved health. The authors call for the continued collaboration of national leaders toward producing integrated and multilevel datasets that link health systems and their GME-sponsoring institutions to evolve SBP.

A Randomized Trial Assessing the Effect of Exercise on Residents' Podcast Knowledge Acquisition and Retention.

PURPOSE: Podcasts are commonly used by residents as part of their learning, with many listening concomitantly with other activities (e.g., driving and exercise). The effects of exercise on learning are controversial, with some suggesting potential benefit and others suggesting impaired learning. This study examined whether exercise influences knowledge acquisition and retention among resident physicians listening to a podcast while exercising versus those with undistracted listening. METHOD: This multicenter, randomized, crossover trial assessed emergency medicine residents across 5 U.S. institutions from September 2022 to January 2023. Residents were randomized to a group that listened to one 30-minute podcast while seated or a group that listened to a 30-minute podcast while engaging in 30 minutes of continuous aerobic exercise, with stratification by site and postgraduate year. Within 30 minutes of completing the podcast, they completed a 20-question multiple-choice test. They subsequently crossed over to the other intervention and listened to a different 30-minute podcast followed by another 20-question test. Each podcast focused on emergency medicine-relevant journal articles that had not been covered in journal club or curriculum at any sites. Residents also completed a 40-question delayed recall test with separate questions on both podcasts at 30 days. RESULTS: Ninety-six residents were recruited for the study, with 95 (99.0%) completing the initial recall portion and 92 (97.0%) completing the delayed recall tests. No statistically significant differences were found between the exercise and seated cohorts on initial recall (74.4% vs 76.3%; d = -0.12; 95% CI, -0.33 to 0.08; P = .12) or delayed recall (52.3% vs 52.5%; d = -0.01; 95% CI, -0.22 to -0.19; P = .46). CONCLUSIONS: Exercising while listening to podcasts did not appear to meaningfully affect knowledge acquisition or retention at 30 days when compared with listening while seated and undistracted.

LIRAGLUTIDE ALLEVIATES ACUTE LUNG INJURY AND MORTALITY IN PNEUMONIA-INDUCED SEPSIS THROUGH REGULATING SURFACTANT PROTEIN EXPRESSION AND SECRETION.

ABSTRACT: Glucagon-like peptide 1 (GLP-1) analogs are used to treat type 2 diabetes, and they can regulate insulin secretion, energy homeostasis, inflammation, and immune cell function. This study sought to determine whether the GLP-1 analog liraglutide exerts a beneficial action in an acute lung injury model of pneumonia-induced sepsis. Methods: Wild-type FVB/NJ mice (n = 114) were infected by intratracheal injection with Pseudomonas aeruginosa Xen5 (4 × 10 4 CFU/mouse) or an equal volume (50 µL) of saline (control) with or without a subcutaneous injection of liraglutide (2 mg/kg, 30 min after infection). Mice were killed 24 h after infection. Lung tissues and BALF were analyzed. In separate experiments, the dynamic growth of bacteria and animal mortality was monitored using in vivo imaging system within 48 h after infection. In addition, primary lung alveolar type II cells isolated from mice were used to study the mechanism of liraglutide action. Result: Liraglutide improved survival ( P < 0.05), decreased bacterial loads in vivo , and reduced lung injury scores ( P < 0.01) in septic mice. Liraglutide-treated mice showed decreased levels of inflammatory cells ( P < 0.01) and proinflammatory cytokines (TNF-α and IL-6) ( P < 0.01) in the lung compared with septic controls. Liraglutide significantly increased pulmonary surfactant proteins (SP-A and SP-B) expression/secretion ( P < 0.01) and phospholipid secretion ( P < 0.01) in vivo . Primary alveolar type II cells pretreated with liraglutide improved SP-A and SP-B expression after LPS exposure ( P < 0.01). Conclusion: Liraglutide attenuates mortality and lung inflammation/injury in pneumonia-induced sepsis. The increased surfactant expression/secretion and anti-inflammatory effects of liraglutide represent potential mechanisms by GLP-1 agonists potentiate host defense and maintain alveolar respiratory function in acute lung injury.

Impact of intestinal microenvironments in obesity and bariatric surgery on shaping macrophages.

Obesity is associated with alterations in tissue composition, systemic cellular metabolism, and low-grade chronic inflammation. Macrophages are heterogenous innate immune cells ubiquitously localized throughout the body and are key components of tissue homeostasis, inflammation, wound healing, and various disease states. Macrophages are highly plastic and can switch their phenotypic polarization and change function in response to their local environments. Here, we discuss how obesity alters the intestinal microenvironment and potential key factors that can influence intestinal macrophages as well as macrophages in other organs, including adipose tissue and hematopoietic organs. As bariatric surgery can induce metabolic adaptation systemically, we discuss the potential mechanisms through which bariatric surgery reshapes macrophages in obesity.

Galantamine improves glycemic control and diabetic nephropathy in Leprdb/db mice.

Galantamine, a centrally acting acetylcholinesterase inhibitor, has been shown to attenuate inflammation and insulin resistance in patients with metabolic syndrome. We investigated the effects of galantamine on glycemic control and development of diabetic nephropathy (DN) in Leprdb/db mice. Galantamine significantly reduced food intake, body weight, blood glucose and HbA1c levels. Insulin resistance (HOMA-IR, QUICKI), HOMA-ß and elevations in plasma inflammatory cytokine levels (TNF-α, IL-6 and HMGB-1) were all attenuated by galantamine. Galantamine also ameliorated diabetes-induced kidney injury as evidenced by improvements in renal function (BUN, creatinine, albuminuria), histologic injury and apoptosis. Improved glycemic control and nephropathy were associated with increased circulating GLP-1, decreased renal P-38 MAPK and caspase-1 activation and reduced SGLT-2 expression. These findings provide insights into the mechanisms by which galantamine improves glycemic control and attenuates DN in the Leprdb/db mouse model.