Conversion Rate of Abstracts Presented at Plastic Surgery The Meeting From 2010 to 2019: A 10-Year Analysis of Factors for Success.

BACKGROUND: Presentations are an important means of knowledge generation. Publication of these studies is important for dissemination of findings beyond meeting attendees. We analyzed a 10-year sample of presented abstracts at Plastic Surgery The Meeting and describe factors that improve rate and speed of conversion to peer-reviewed publication. METHODS: Abstracts presented between 2010 and 2019 at Plastic Surgery The Meeting were sourced from the American Society of Plastic Surgery Abstract Archive. A random sample of 100 abstracts from each year was evaluated. Abstract information and demographics were recorded. The title or author and keywords of each abstract were searched using a standardized workflow to find a corresponding published paper on PubMed, Google Scholar, and Google. Data were analyzed for trends and factors affecting conversion rate. RESULTS: A total of 983 presented abstracts were included. The conversion rate was 54.1%. Residents and fellows constituted the largest proportion of presenters (38.4%). There was a significant increase in medical student and research fellow presenters during the study period (P < 0.001). Conversion rate was not affected by the research rank of a presenter's affiliated institution (ß = 1.001, P = 0.89), geographic location (P = 0.60), or subspecialty tract (P = 0.73). US academics had a higher conversion rate (61.8%) than US nonacademics (32.7%) or international presenters (47.1%) (P < 0.001). Medical students had the highest conversion rate (65.6%); attendings had the lowest (45.0%). Research fellows had the lowest average time to publication (11.6 months, P = 0.007). CONCLUSIONS: Lower levels of training, factors associated with increased institution-level support, and research quality affect rate and time to publication. These findings highlight the success of current models featuring medical student and research fellow-led projects with strong resident and faculty mentorship.

Multiple Dosing and Preactivation of Mesenchymal Stromal Cells Enhance Efficacy in Established Pneumonia Induced by Antimicrobial-Resistant Klebsiella pneumoniae in Rodents.

Antimicrobial-resistant (AMR) bacteria, such as Klebsiella species, are an increasingly common cause of hospital-acquired pneumonia, resulting in high mortality and morbidity. Harnessing the host immune response to AMR bacterial infection using mesenchymal stem cells (MSCs) is a promising approach to bypass bacterial AMR mechanisms. The administration of single doses of naïve MSCs to ARDS clinical trial patient cohorts has been shown to be safe, although efficacy is unclear. The study tested whether repeated MSC dosing and/or preactivation, would attenuate AMR Klebsiella pneumonia-induced established pneumonia. Rat models of established K. pneumoniae-induced pneumonia were randomised to receive intravenous naïve or cytomix-preactivated umbilical cord MSCs as a single dose at 24 h post pneumonia induction with or without a subsequent dose at 48 h. Physiological indices, bronchoalveolar lavage (BAL), and tissues were obtained at 72 h post pneumonia induction. A single dose of naïve MSCs was largely ineffective, whereas two doses of MSCs were effective in attenuating Klebsiella pneumosepsis, improving lung compliance and oxygenation, while reducing bacteria and injury in the lung. Cytomix-preactivated MSCs were superior to naïve MSCs. BAL neutrophil counts and activation were reduced, and apoptosis increased. MSC therapy reduced cytotoxic BAL T cells, and increased CD4+/CD8+ ratios. Systemically, granulocytes, classical monocytes, and the CD4+/CD8+ ratio were reduced, and nonclassical monocytes were increased. Repeated doses of MSCs-particularly preactivated MSCs-enhance their therapeutic potential in a clinically relevant model of established AMR K. pneumoniae-induced pneumosepsis.

Fresh and Cryopreserved Human Umbilical-Cord-Derived Mesenchymal Stromal Cells Attenuate Injury and Enhance Resolution and Repair following Ventilation-Induced Lung Injury.

BACKGROUND: Ventilator-induced lung injury (VILI) frequently worsens acute respiratory distress syndrome (ARDS) severity. Human mesenchymal stem/stromal cells (MSCs) offer considerable therapeutic promise, but the key impediments of clinical translation stem from limitations due to cell source and availability, and concerns regarding the loss of efficacy following cryopreservation. These experiments compared the efficacy of umbilical-cord-derived MSCs (UC-MSCs), a readily available and homogenous tissue source, to the previously more widely utilised bone-marrow-derived MSCs (BM-MSCs). We assessed their capacity to limit inflammation, resolve injury and enhance repair in relevant lung mechanical stretch models, and the impact of cryopreservation on therapeutic efficacy. METHODS: In series 1, confluent alveolar epithelial layers were subjected to cyclic mechanical stretch (22% equibiaxial strain) and wound injury, and the potential of the secretome from BM- and UC-derived MSCs to attenuate epithelial inflammation and cell death, and enhance wound repair was determined. In series 2, anesthetized rats underwent VILI, and later received, in a randomised manner, 1 × 107 MSCs/kg intravenously, that were: (i) fresh BM-MSCs, (ii) fresh UC-MSCs or (iii) cryopreserved UC-MSCs. Control animals received a vehicle (PBS). The extent of the resolution of inflammation and injury, and repair was measured at 24 h. RESULTS: Conditioned medium from BM-MSCs and UC-MSCs comparably decreased stretch-induced pulmonary epithelial inflammation and cell death. BM-MSCs and UC-MSCs comparably enhanced wound resolution. In animals subjected to VILI, both fresh BM-MSCs and UC-MSCs enhanced injury resolution and repair, while cryopreserved UC-MSCs comparably retained their efficacy. CONCLUSIONS: Cryopreserved UC-MSCs can reduce stretch-induced inflammation and cell death, enhance wound resolution, and enhance injury resolution and repair following VILI. Cryopreserved UC-MSCs represent a more abundant, cost-efficient, less variable and equally efficacious source of therapeutic MSC product.

Survival/Adaptation of Bone Marrow-Derived Mesenchymal Stem Cells After Long-Term Starvation Through Selective Processes.

After in vivo transplantation, mesenchymal stem cells (MSC) face an ischemic microenvironment, characterized by nutrient deprivation and reduced oxygen tension, which reduces their viability and thus their therapeutic potential. Therefore, MSC response to models of in vitro ischemia is of relevance for improving their survival and therapeutic efficacy. The aim of this study was to understand the survival/adaptive response mechanism that MSC use to respond to extreme culture conditions. Specifically, the effect of a long-term starvation on human bone marrow (hBM)-derived MSC cultured in a chemically defined medium (fetal bovine serum-free [SF] and human SF), either in hypoxic or normoxic conditions. We observed that hBM-MSC that were isolated and cultured in SF medium and subjected to a complete starvation for up to 75 days transiently changed their behavior and phenotype. However, at the end of that period, hBM-MSC retained their characteristics as determined by their morphology, DNA damage resistance, proliferation kinetic, and differentiation potential. This survival mode involved a quiescent state, confirmed by increased expression of cell cycle regulators p16, p27, and p57 and decreased expression of proliferating cell nuclear antigen (PCNA), Ki-67, mTOR, and Nanog. In addition, Jak/STAT (STAT6) antiapoptotic activity selected which cells conserved stemness and that supported metabolic, bioenergetic, and scavenging requirements. We also demonstrated that hBM-MSC exploited an autophagic process which induced lipid ß-oxidation as an alternative energy source. Priming MSC by concomitant starvation and culture in hypoxic conditions to induce their quiescence would be of benefit to increase MSC survival when transplanted in vivo. Stem Cells 2019;37:813-827.

Umbilical Cord-Derived CD362+ Mesenchymal Stromal Cells Attenuate Polymicrobial Sepsis Induced by Caecal Ligation and Puncture.

Mesenchymal stromal cells (MSCs) have a multimodal, immunomodulatory mechanism of action and are now in clinical trials for single organ and systemic sepsis. However, a number of practicalities around source, homogeneity and therapeutic window remain to be determined. Here, we utilised conditioned medium from CD362+-sorted umbilical cord-human MSCs (UC-hMSCs) for a series of in vitro anti-inflammatory assays and the cryopreserved MSCs themselves in a severe (Series 1) or moderate (Series 2+3) caecal ligation and puncture (CLP) rodent model. Surviving animals were assessed at 48 h post injury induction. MSCs improved human lung, colonic and kidney epithelial cell survival following cytokine activation. In severe systemic sepsis, MSCs administered at 30 min enhanced survival (Series 1), and reduced organ bacterial load. In moderate systemic sepsis (Series 2), MSCs were ineffective when delivered immediately or 24 h later. Of importance, MSCs delivered 4 h post induction of moderate sepsis (Series 3) were effective, improving serum lactate, enhancing bacterial clearance from tissues, reducing pro-inflammatory cytokine concentrations and increasing antimicrobial peptides in serum. While demonstrating benefit and immunomodulation in systemic sepsis, therapeutic efficacy may be limited to a specific point of disease onset, and repeat dosing, MSC enhancement or other contingencies may be necessary.

Breast Implant-Associated Anaplastic Large Cell Lymphoma: What the Primary Care Physician Needs to Know.

This manuscript aims to outline the pertinent epidemiology, presentation, diagnosis, and treatment of patients who present with breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) as it pertains to primary care, such that the primary care physician (PCP) is able to appropriately care for patients with breast implants and counsel on risks of BIA-ALCL.

Evaluation of the Immunomodulatory Effects of All-Trans Retinoic Acid Solid Lipid Nanoparticles and Human Mesenchymal Stem Cells in an A549 Epithelial Cell Line Model.

PURPOSE: To investigate two potential strategies aimed at targeting the inflammatory pathogenesis of COPD: a small molecule, all trans retinoic acid (atRA) and human mesenchymal stem cells (hMSCs). METHODS: atRA was formulated into solid lipid nanoparticles (SLNs) via the emulsification-ultrasonication method, and these SLNs were characterised physicochemically. Assessment of the immunomodulatory effects of atRA-SLNs on A549 cells in vitro was determined using ELISA. hMSCs were suspended in a previously developed methylcellulose, collagen and beta-glycerophosphate hydrogel prior to investigating their immunomodulatory effects in vitro. RESULTS: SLNs provided significant encapsulation of atRA and also sustained its release over 72 h. A549 cells were viable following the addition of atRA SLNs and showed a reduction in IL-6 and IL-8 levels. A549 cells also remained viable following addition of the hMSC/hydrogel formulation - however, this formulation resulted in increased levels of IL-6 and IL-8, indicating a potentially pro-inflammatory effect. CONCLUSION: Both atRA SLNs and hMSCs show potential for modulating the environment in inflammatory disease, though through different mechanisms and leading to different outcomes - despite both being explored as strategies for use in inflammatory disease. atRA shows promise by acting in a directly anti-inflammatory manner, whereas further research into the exact mechanisms and behaviours of hMSCs in inflammatory diseases is required.

Adherence to Aerosol Therapy in Young People With Cystic Fibrosis: Patient and Parent Perspectives Following Electronic Data Capture.

The benefits of improved treatments for cystic fibrosis (CF) depend on optimal adherence, which remains problematic, particularly to aerosol therapy. In this study, we explored the process of adhering to aerosol therapy from the perspective of both adolescents with CF and their parents. Interviews were conducted individually with six adolescents and six parents, informed by accurate adherence data from an electronically chipped, aerosol device. Interview transcripts from audio-recordings were analyzed using grounded theory method (GTM). Major themes revealed differences in perspective between parent and adolescent, with this relationship mediating the cognitive and emotional processes that play a significant role in adherence behavior. These processes are further influenced by interactions with the aerosol therapy treatment regimen, device characteristics, and the context in which adherence is taking place. Parents and adolescents have different views of treatment and how to manage it. Both need to be addressed if optimal adherence is to be achieved.

Syndecan-2-positive, Bone Marrow-derived Human Mesenchymal Stromal Cells Attenuate Bacterial-induced Acute Lung Injury and Enhance Resolution of Ventilator-induced Lung Injury in Rats.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Human mesenchymal stromal cells demonstrate promise for acute respiratory distress syndrome, but current studies use highly heterogenous cell populations. We hypothesized that a syndecan 2 (CD362)-expressing human mesenchymal stromal cell subpopulation would attenuate Escherichia coli-induced lung injury and enhance resolution after ventilator-induced lung injury. METHODS: In vitro studies determined whether CD362 human mesenchymal stromal cells could modulate pulmonary epithelial inflammation, wound healing, and macrophage phagocytosis. Two in vivo rodent studies determined whether CD362 human mesenchymal stromal cells attenuated Escherichia coli-induced lung injury (n = 10/group) and enhanced resolution of ventilation-induced injury (n = 10/group). RESULTS: CD362 human mesenchymal stromal cells attenuated cytokine-induced epithelial nuclear factor kappa B activation, increased epithelial wound closure, and increased macrophage phagocytosis in vitro. CD362 human mesenchymal stromal cells attenuated Escherichia coli-induced injury in rodents, improving arterial oxygenation (mean ± SD, 83 ± 9 vs. 60 ± 8 mmHg, P < 0.05), improving lung compliance (mean ± SD: 0.66 ± 0.08 vs. 0.53 ± 0.09 ml · cm H2O, P < 0.05), reducing bacterial load (median [interquartile range], 1,895 [100-3,300] vs. 8,195 [4,260-8,690] colony-forming units, P < 0.05), and decreasing structural injury compared with vehicle. CD362 human mesenchymal stromal cells were more effective than CD362 human mesenchymal stromal cells and comparable to heterogenous human mesenchymal stromal cells. CD362 human mesenchymal stromal cells enhanced resolution after ventilator-induced lung injury in rodents, restoring arterial oxygenation (mean ± SD: 113 ± 11 vs. 89 ± 11 mmHg, P < 0.05) and lung static compliance (mean ± SD: 0.74 ± 0.07 vs. 0.45 ± 0.07 ml · cm H2O, P < 0.05), resolving lung inflammation, and restoring histologic structure compared with vehicle. CD362 human mesenchymal stromal cells efficacy was at least comparable to heterogenous human mesenchymal stromal cells. CONCLUSIONS: A CD362 human mesenchymal stromal cell population decreased Escherichia coli-induced pneumonia severity and enhanced recovery after ventilator-induced lung injury.

Human Mesenchymal Stem Cell Secretome from Bone Marrow or Adipose-Derived Tissue Sources for Treatment of Hypoxia-Induced Pulmonary Epithelial Injury.

: Alveolar epithelial dysfunction induced by hypoxic stress plays a significant role in the pathological process of lung ischemia-reperfusion injury (IRI). Mesenchymal stem cell (MSC) therapies have demonstrated efficacy in exerting protective immunomodulatory effects, thereby reducing airway inflammation in several pulmonary diseases. AIM: This study assesses the protective effects of MSC secretome from different cell sources, human bone marrow (BMSC) and adipose tissue (ADSC), in attenuating hypoxia-induced cellular stress and inflammation in pulmonary epithelial cells. METHODS: Pulmonary epithelial cells, primary rat alveolar epithelial cells (AEC) and A549 cell line were pre-treated with BMSC, or ADSC conditioned medium (CM) and subjected to hypoxia for 24 h. RESULTS: Both MSC-CM improved cell viability, reduced secretion of pro-inflammatory mediators and enhanced IL-10 anti-inflammatory cytokine production in hypoxic injured primary rat AECs. ADSC-CM reduced hypoxic cellular injury by mechanisms which include: inhibition of p38 MAPK phosphorylation and nuclear translocation of subunits in primary AECs. Both MSC-CM enhanced translocation of Bcl-2 to the nucleus, expression of cytoprotective glucose-regulated proteins (GRP) and restored matrix metalloproteinases (MMP) function, thereby promoting repair and cellular homeostasis, whereas inhibition of GRP chaperones was detrimental to cell survival. CONCLUSIONS: Elucidation of the protective mechanisms exerted by the MSC secretome is an essential step for maximizing the therapeutic effects, in addition to developing therapeutic targets-specific strategies for various pulmonary syndromes.

Cryopreserved, Xeno-Free Human Umbilical Cord Mesenchymal Stromal Cells Reduce Lung Injury Severity and Bacterial Burden in Rodent Escherichia coli-Induced Acute Respiratory Distress Syndrome.

OBJECTIVE: Although mesenchymal stem/stromal cells represent a promising therapeutic strategy for acute respiratory distress syndrome, clinical translation faces challenges, including scarcity of bone marrow donors, and reliance on bovine serum during mesenchymal stem/stromal cell proliferation. We wished to compare mesenchymal stem/stromal cells from human umbilical cord, grown in xeno-free conditions, with mesenchymal stem/stromal cells from human bone marrow, in a rat model of Escherichia coli pneumonia. In addition, we wished to determine the potential for umbilical cord-mesenchymal stem/stromal cells to reduce E. coli-induced oxidant injury. DESIGN: Randomized animal study. SETTING: University research laboratory. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: Acute respiratory distress syndrome was induced in rats by intratracheal instillation of E. coli (1.5-2 × 10 CFU/kg). "Series 1" compared the effects of freshly thawed cryopreserved umbilical cord-mesenchymal stem/stromal cells with bone marrow-mesenchymal stem/stromal cells on physiologic indices of lung injury, cellular infiltration, and E. coli colony counts in bronchoalveolar lavage. "Series 2" examined the effects of cryopreserved umbilical cord-mesenchymal stem/stromal cells on survival, as well as measures of injury, inflammation and oxidant stress, including production of reactive oxidative species, reactive oxidative species scavenging by superoxide dismutase-1 and superoxide dismutase-2. MEASUREMENTS AND MAIN RESULTS: In "Series 1," animals subjected to E. coli pneumonia who received umbilical cord-mesenchymal stem/stromal cells had improvements in oxygenation, respiratory static compliance, and wet-to-dry ratios comparable to bone marrow-mesenchymal stem/stromal cell treatment. E. coli colony-forming units in bronchoalveolar lavage were reduced in both cell therapy groups, despite a reduction in bronchoalveolar lavage neutrophils. In series 2, umbilical cord-mesenchymal stem/stromal cells enhanced animal survival and decreased alveolar protein and proinflammatory cytokine concentrations, whereas increasing interleukin-10 concentrations. Umbilical cord-mesenchymal stem/stromal cell therapy decreased nicotinamide adenine dinucleotide phosphate-oxidase 2 and inducible nitric oxide synthase and enhanced lung concentrations of superoxide dismutase-2, thereby reducing lung tissue reactive oxidative species concentrations. CONCLUSIONS: Our results demonstrate that freshly thawed cryopreserved xeno-free human umbilical cord-mesenchymal stem/stromal cells reduce the severity of rodent E. coli-induced acute respiratory distress syndrome. Umbilical cord-mesenchymal stem/stromal cells, therefore, represent an attractive option for future clinical trials in acute respiratory distress syndrome.

Effects and Mechanisms by Which Hypercapnic Acidosis Inhibits Sepsis-Induced Canonical Nuclear Factor-κB Signaling in the Lung.

OBJECTIVE: Diverse effects of hypercapnic acidosis are mediated via inhibition of nuclear factor-κB, a pivotal transcription factor, in the setting of injury, inflammation, and repair, but the underlying mechanisms of action of hypercapnic acidosis on this pathway is unclear. We aim to examine the effect of hypercapnic acidosis on the nuclear factor-κB pathway in the setting of Escherichia coli-induced lung injury and characterize the underlying mechanisms in subsequent in vitro studies. DESIGN: In vivo animal study and subsequent in vitro studies. SETTING: University Research Laboratory. SUBJECTS: Adult male Sprague-Dawley rats and pulmonary epithelial cells. INTERVENTIONS: Following pulmonary IκBα-SuperRepressor transgene overexpression or sham and intratracheal E. coli inoculation, rats underwent 4 hours of mechanical ventilation under normocapnia or hypercapnic acidosis, and nuclear factor-κB activation, animal survival, lung injury, and cytokine profile were assessed. Subsequent in vitro studies examined the effect of hypercapnic acidosis on specific nuclear factor-κB canonical pathway kinases via overexpression of these components and in vitro kinase activity assays. The effect of hypercapnic acidosis on the p50/p65 nuclear factor-κB heterodimer was then assessed. MEASUREMENTS AND MAIN RESULTS: Hypercapnic acidosis and IκBα-SuperRepressor transgene overexpression reduced E. coli-induced lung inflammation and injury, decreased nuclear factor-κB activity, and increased animal survival. Hypercapnic acidosis inhibited canonical nuclear factor-κB signaling via reduced phosphorylative activation, reducing IκB kinase-ß activation and intrinsic activity, thereby decreasing IκBα degradation, and subsequent nuclear factor-κB translocation. Hypercapnic acidosis also directly reduced DNA binding of the nuclear factor-κB p65 subunit, although this effect was less marked. CONCLUSIONS: Hypercapnic acidosis reduced E. coli inflammation and lung injury in vivo and reduced nuclear factor-κB activation predominantly by inhibiting the activation and intrinsic activity of IκB kinase-ß.

Human mesenchymal stromal cells decrease the severity of acute lung injury induced by E. coli in the rat.

BACKGROUND: Mesenchymal stromal cells (MSCs) demonstrate considerable promise in preclinical acute respiratory distress syndrome models. We wished to determine the efficacy and mechanisms of action of human MSCs (hMSCs) in the setting of acute lung injury induced by prolonged Escherichia coli pneumonia in the rat. METHODS: Adult male Sprague Dawley rats underwent intratracheal instillation of E. coli bacteria in all experiments. In Series 1, animals were randomised to intravenous administration of: (1) vehicle (phosphate buffered saline (PBS), 300 µL); (2) 1×10(7) fibroblasts/kg; (3) 1×10(7) hMSCs/kg or (4) 2×10(7) hMSCs/kg. Series 2 determined the lowest effective hMSC dose. Series 3 compared the efficacy of intratracheal versus intravenous hMSC administration, while Series 4 examined the efficacy of cryopreserved hMSC. Series 5 examined the efficacy of the hMSC secretome. Parallel in vitro experiments further assessed the potential for hMSCs to secrete LL-37 and modulate macrophage phagocytosis. RESULTS: hMSC therapy reduced the severity of rodent E. coli pneumonia, improving survival, decreasing lung injury, reducing lung bacterial load and suppressing inflammation. Doses as low as 5×10(6) hMSCs/kg were effective. Intratracheal hMSC therapy was as effective as intravenous hMSC. Cryopreserved hMSCs were also effective, while the hMSC secretome was less effective in this model. hMSC therapy enhanced macrophage phagocytic capacity and increased lung and systemic concentrations of the antimicrobial peptide LL37. CONCLUSIONS: hMSC therapy decreased E. coli induced pneumonia injury and reduced lung bacterial burden, potentially via enhanced macrophage phagocytosis and increased alveolar LL-37 concentrations.

Therapeutic efficacy of human mesenchymal stromal cells in the repair of established ventilator-induced lung injury in the rat.

BACKGROUND: Rodent mesenchymal stem/stromal cells (MSCs) enhance repair after ventilator-induced lung injury (VILI). We wished to determine the therapeutic potential of human MSCs (hMSCs) in repairing the rodent lung. METHODS: In series 1, anesthetized rats underwent VILI (series 1A, n = 8 to 9 per group) or protective ventilation (series 1B, n = 4 per group). After VILI, they were randomized to intravenous administration of (1) vehicle (phosphate-buffered saline); (2) fibroblasts (1 × 10 cells/kg); or (3) human MSCs (1 × 10 cells/kg) and the effect on restoration of lung function and structure assessed. In series 2, the efficacy of hMSC doses of 1, 2, 5, and 10 million/kg was examined (n = 8 per group). Series 3 compared the efficacy of both intratracheal and intraperitoneal hMSC administration to intravascular delivery (n = 5-10 per group). Series 4 examined the efficacy of delayed hMSC administration (n = 8 per group). RESULTS: Human MSC's enhanced lung repair, restoring oxygenation (131 ± 19 vs. 103 ± 11 vs. 95 ± 11 mmHg, P = 0.004) compared to vehicle or fibroblast therapy, respectively. hMSCs improved lung compliance, reducing alveolar edema, and restoring lung architecture. hMSCs attenuated lung inflammation, decreasing alveolar cellular infiltration, and decreasing cytokine-induced neutrophil chemoattractant-1 and interleukin-6 while increasing keratinocyte growth factor concentrations. The lowest effective hMSC dose was 2 × 10 hMSC/kg. Intraperitoneal hMSC delivery was less effective than intratracheal or intravenous hMSC. hMSCs enhanced lung repair when administered at later time points after VILI. CONCLUSIONS: hMSC therapy demonstrates therapeutic potential in enhancing recovery after VILI.

Inhibition of pulmonary nuclear factor kappa-B decreases the severity of acute Escherichia coli pneumonia but worsens prolonged pneumonia.

INTRODUCTION: Nuclear factor (NF)-κB is central to the pathogenesis of inflammation in acute lung injury, but also to inflammation resolution and repair. We wished to determine whether overexpression of the NF-κB inhibitor IκBα could modulate the severity of acute and prolonged pneumonia-induced lung injury in a series of prospective randomized animal studies. METHODS: Adult male Sprague-Dawley rats were randomized to undergo intratracheal instillation of (a) 5 × 109 adenoassociated virus (AAV) vectors encoding the IκBα transgene (5 × 109 AAV-IκBα); (b) 1 × 10¹° AAV-IκBα; (c) 5 × 10¹° AAV-IκBα; or (d) vehicle alone. After intratracheal inoculation with Escherichia coli, the severity of the lung injury was measured in one series over a 4-hour period (acute pneumonia), and in a second series after 72 hours (prolonged pneumonia). Additional experiments examined the effects of IκBα and null-gene overexpression on E. coli-induced and sham pneumonia. RESULTS: In acute pneumonia, IκBα dose-dependently decreased lung injury, improving arterial oxygenation and lung static compliance, reducing alveolar protein leak and histologic injury, and decreasing alveolar IL-1ß concentrations. Benefit was maximal at the intermediate (1 × 10¹°) IκBα vector dose; however, efficacy was diminished at the higher (5 × 10¹°) IκBα vector dose. In contrast, IκBα worsened prolonged pneumonia-induced lung injury, increased lung bacterial load, decreased lung compliance, and delayed resolution of the acute inflammatory response. CONCLUSIONS: Inhibition of pulmonary NF-κB activity reduces early pneumonia-induced injury, but worsens injury and bacterial load during prolonged pneumonia.

Nebulized mesenchymal stem cell derived conditioned medium ameliorates Escherichia coli induced pneumonia in a rat model.

Background: Mesenchymal stem cells (MSC) have shown immense therapeutic promise in a range of inflammatory diseases, including acute respiratory distress syndrome (ARDS), and are rapidly advancing through clinical trials. Among their multimodal mechanisms of action, MSCs exert strong immunomodulatory effects via their secretome, which contains cytokines, small molecules, extracellular vesicles, and a range of other factors. Recent studies have shown that the MSC secretome can recapitulate many of the beneficial effects of the MSC itself. We aimed to determine the therapeutic capacity of the MSC secretome in a rat bacterial pneumonia model, especially when delivered directly to the lung by nebulization which is a technique more appropriate for the ventilated patient. Methods: Conditioned medium (CM) was generated from human bone marrow derived MSCs in the absence of antibiotics and serum supplements. Post-nebulization lung penetration was estimated through nebulization of CM to a cascade impactor and simulated lung and quantification of collected total protein and IL-8 cytokine. Control and nebulized CM was added to a variety of lung cell culture models and injury resolution assessed. In a rat E. coli pneumonia model, CM was instilled or administered by nebulization and lung injury and inflammation assessed at 48 h. Results: MSC-CM was predicted to have good distal lung penetration and delivery when administered by nebulizer. Both control and nebulized CM reduced NF-κB activation and inflammatory cytokine production in lung cell culture, while promoting cell viability and would closure in oxidative stress and scratch wound models. In a rat bacterial pneumonia model, both instilled and nebulizer delivered CM improved lung function, increasing blood oxygenation and reducing carbon dioxide levels compared to unconditioned medium controls. A reduction in bacterial load was also observed in both treatment groups. Inflammatory cytokines were reduced significantly by both liquid and aerosol CM administration, with less IL-1ß, IL-6, and CINC1 in these groups compared to controls. Conclusion: MSC-CM is a potential therapeutic for pneumonia ARDS, and administration is compatible with vibrating mesh nebulization.

Delayed MSC therapy enhances resolution of organized pneumonia induced by antibiotic resistant Klebsiella pneumoniae infection.

Introduction: Mesenchymal stromal cells (MSC) are a promising therapeutic for pneumonia-induced sepsis. Here we sought to determine the efficacy of delayed administration of naïve and activated bone marrow (BM), adipose (AD), and umbilical cord (UC) derived MSCs in organized antibiotic resistant Klebsiella pneumosepsis. Methods: Human BM-, AD-, and UC-MSCs were isolated and expanded and used either in the naïve state or following cytokine pre-activation. The effect of MSC tissue source and activation status was assessed first in vitro. Subsequent experiments assessed therapeutic potential as a delayed therapy at 48 h post infection of rodents with Klebsiella pneumoniae, with efficacy assessed at 120 h. Results: BM-, AD-, and UC-MSCs accelerated epithelial healing, increased phagocytosis, and reduced ROS-induced epithelial injury in vitro, with AD-MSCs less effective, and naïve MSCs more effective than pre-activated MSCs. Delayed MSC administration in pre-clinical organized Klebsiella pneumosepsis had no effect on physiologic indices, but enhanced resolution of structural lung injury. Delayed therapy with pre-activated MSCs reduced mRNA concentrations of fibrotic factors. Naïve MSC treatment reduced key circulating cell proportions and increased bacterial killing capacity in the lungs whereas pre-activated MSCs enhanced the phagocytic index of pulmonary white cells. Discussion: Delayed MSC therapy enhanced resolution of lung injury induced by antibiotic resistant Klebsiella infection and favorably modulated immune cell profile. Overall, AD-MSCs were less effective than either UC- or BM-MSCs, while naïve MSCs had a more favorable effect profile compared to pre-activated MSCs.