Citations

Background Superimposition of the metabolic syndrome (MetS) on renovascular disease (RVD) amplifies intrarenal microvascular loss. Extracellular vesicles (EVs) released from adipose tissue‐derived mesenchymal stem/stromal cells (MSCs) may mediate their paracrine effect, but their efficacy to protect the renal microcirculation in RVD complicated by MetS remains unclear. Using a novel swine model, we tested the hypothesis that EVs would attenuate microvascular loss in MetS+RVD. Methods Four groups of pigs (n=7 each) were studied after 16 weeks of diet‐induced MetS and unilateral RVD (MetS+RVD), MetS+RVD treated 4 weeks earlier with a single intra‐renal delivery of pre‐labeled EVs harvested from autologous MSCs, and Lean and MetS Sham controls. Stenotic‐kidney renal blood flow (RBF) and glomerular filtration rate (GFR) were measured in‐vivo (fast CT), whereas EV characteristics, renal microvascular architecture (micro‐CT), and injury pathways ex‐vivo. Results mRNA sequencing of EVs and their parent MSCs revealed that EVs were enriched with pro‐angiogenic genes, including vascular endothelial growth factor (VEGF)‐A, VEGF–C, and Von Willebrand Factor (vWF)‐A Domain Containing‐1 (VWA)‐1 (). In addition, protein expression of VEGF and vWF was higher in EVs compared to MSCs (). EVs were detected in the stenotic‐kidney ex‐vivo internalized by tubular and endothelial cells. EVs restored renal expression of the pro‐angiogenic factors VEGF, Notch‐1, and Notch ligand delta‐like‐4 (DLL4) and improved cortical microvascular density (). Tubulointerstitial fibrosis increased and RBF and GFR decreased in MetS+RVD vs. MetS, but were restored in MetS+RVD+EV (). Conclusions Intra‐renal delivery of MSC‐derived EVs bearing pro‐angiogenic properties in swine MetS+RVD restored stenotic‐kidney microcirculation, and in turn its hemodynamics and function. Our study suggests a novel therapeutic potential for MSC‐derived EVs in restoring renal function in chronic experimental MetS+RVD. Support or Funding Information This study was partly supported by NIH grant numbers DK73608, DK104273, HL123160, and DK102325, DK106427, the Mayo Clinic Center for Regenerative Medicine, and the Mayo Clinic Mary Kathryn and Michael B. Panitch Career Development Award.

Airway inflammation is a key aspect of asthma and is associated with airway smooth muscle (ASM) hyperreactivity (airway narrowing due to increased Ca 2+ and force responses to agonist stimulation) as well as airway remodeling (ASM cell proliferation and altering extracellular matrix composition). Proinflammatory cytokines, such as TNF‐α mediate this airway inflammatory response. Previously, we found that the TNF‐α induces an increase ASM force, which is associated with an increase in ATP hydrolysis, imposing a metabolic stress on ASM. Mitochondria play an important role in providing ATP to support contraction in ASM. Mitochondria are dynamically remodelling within ASM cells displaying changing filamentous or fragmented tubular networks. Changing expression of Mitofusin 2 (Mfn2), which is associated with mitochondria fusion, or Dynamin Related Protein 1 (Drp1), which is associated with fission mediate this mitochondrial remodelling. The stressors that induce mitochondrial remodelling in ASM are unknown, but mitochondrial fragmentation may be an initial step in mitochondrial biogenesis to meet increasing energy demand. We hypothesized that human ASM (hASM) cells exposed to TNF‐α will display reduced Mfn2 and increased Drp1 expression resulting in mitochondrial fragmentation and mitochondrial biogenesis. To test our hypothesis, serum‐deprived primary hASM cells were exposed to 20 ng/ml TNF‐α for 24 h after which they were loaded with 500 μM MitoTracker Green to visualize mitochondria and imaged using confocal microscopy. Images were analyzed using MATLAB Image J software to quantify mitochondrial morphometry: form factor and aspect ratio. An increase in form factor and aspect ratio indicates greater mitochondrial filamentous networks. Expression of Mfn2 and Drp1 were determined by Western blot analysis. In hASM exposed to TNF‐α, Mfn2 expression decreased by ~40%, while Drp1 expression increased by ~75% compared to controls. These changes in fusion/fission proteins were associated with mitochondrial fragmentation (reduced form factor and aspect ratio) and an increase in mitochondria number. Our results indicate that hASM cells exposed to TNF‐α display mitochondrial fragmentation due to changes in Mfn2 and Drp1 expression. Mitochondrial fragmentation may be involved in mitochondrial biogenesis in response to increased metabolic demands imposed by airway hyperreactivity. Support or Funding Information APS fellowship (EK) and NIH grant HL126451 (GCS)

In excitation‐contraction coupling, a transient elevation of cytosolic Ca 2+ concentration ([Ca 2+ ] cyt ) triggers a force response. The Ca 2+ sensitivity of muscle reflects the relationship between [Ca 2+ ] cyt and force, and in skeletal and cardiac muscle is often defined as the [Ca 2+ ] cyt at which 50% force is generated. In smooth muscle, Ca 2+ sensitivity has been assessed as the ratio of peak force to peak cytosolic [Ca 2+ ] cyt . However, this measurement overlooks the dynamic nature of Ca 2+ regulation of force generation. In the present study, in order to provide a dynamic index of Ca 2+ sensitivity in airway smooth muscle (ASM), we simultaneously measured [Ca 2+ ] cyt and force and determined their temporal dependence using a phase loop plot. We hypothesized that [Ca 2+ ] cyt /force phase loop plot in ASM would be altered by conditions in which the extent of regulatory myosin light chain (rMLC) phosphorylation was affected. Intact ASM strips were isolated from porcine tracheas obtained from local abattoir. ASM strips, were loaded with Fura‐2 AM (Ca 2+ fluorescent indicator) and stimulated using 1 μM ACh. Isometric force and [Ca 2+ ] cyt responses were simultaneously measured using a Guth Muscle Research System. In the first set of experiments we examined the effect of Y27623, a Rho‐kinase inhibitor, and calyculin A, a protein phosphatase inhibitor that affected Ca 2+ ‐induced rMLC phosphorylation. In a second set of experiments, we examined the effect of cytochalasin D (Cyto‐D), an inhibitor of actin polymerization, which reduces force independent of Ca 2+ ‐induced rMLC phosphorylation. As expected, Y27623 decreased ACh‐induced isometric force but had no effect on evoked [Ca 2+ ] cyt transients. Cyto‐D also decreased force with no effects on evoked [Ca 2+ ] cyt . By comparison, calyculin A increased force with no effect on [Ca 2+ ] cyt . Although these results suggest changes in Ca 2+ sensitivity, the phase loop plots showed no significant shift indicative of changes in dynamic Ca 2+ sensitivity. These results do not support our hypothesis that dynamic Ca 2+ sensitivity in ASM is modulated by the extent of rMLC phosphorylation. Under these experimental conditions, it appears that isometric force generation in ASM is not entirely dependent on [Ca 2+ ] cyt . Support or Funding Information Supported by NIH grant HL126451 (GCS)

In previous studies, we found that prolonged hypothermia (2 h or greater) followed by rewarming induces cardiac contractile dysfunction (rewarming shock) mimicking the effects of accidental hypothermia followed by rapid rewarming in trauma patients. We found that rewarming shock was also presented in isolated cardiomyocytes in which reduced contractility was attributed to PKA‐mediated TnI phosphorylation and reduced Ca 2+ sensitivity. During hypothermia rewarming in cardiomyocytes there is increased production of reactive oxidant species (ROS ‐ superoxide anion), which may trigger the intracellular mechanisms underlying reduced contractility. We hypothesized that in cardiomyocytes, hypothermia/rewarming‐induced ROS production is due to altered mitochondrial respiratory function. To test this hypothesis, isolated cardiomyocytes from 6 rats underwent the following hypothermia/rewarming protocol in which they were electrically stimulated every 2 s: experimental temperature was cooled from 35°C to 15°C during the initial 30 min, then maintained at 15°C for 2 h, followed by rewarming to 35°C in the final 30 min. Time‐matched control cardiomyocytes were also electrically stimulated every 2 s and maintained at 35°C for 3 h. After the 3‐h protocol, cardiomyocytes were placed into separate chambers of an Oroboros Oxygraph (high‐resolution respirometry) to measure O 2 consumption rate (OCR) under varying conditions. Initially, basal OCR was measured for 5 min followed by serial exposure to oligomycin (1 μM for 5 min) to block ATP synthase activity, FCCP (0.5 μM repeated 3 times for 5 min each) an H + ionophore to dissipate mitochondrial membrane potential; and antimycin‐A (0.5 μM for 5 min) to block the electron transport chain. This procedure allowed assessment of the key parameters of mitochondrial respiratory function: basal and maximal respiration (after FCCP exposure), ATP production and proton leak (after oligomycin), and reserve respiratory capacity (calculated after antimycin‐A). We found that compared to control cardiomyocytes, hypothermia/rewarming decreased key parameters of mitochondrial function, which suggests that altered mitochondrial function may have contributed to increased ROS production. In addition, decreased OCR following rewarming may contribute to contractile dysfunction by limiting ATP supply in response to metabolic demand, as well as by contributing to a decline in cell viability (e.g., triggering apoptosis). Support or Funding Information 5T32HL105355 (NSS); Norwegian Air Ambulance Foundation (YSH)

Objective Activation of brain microvascular endothelium by inflammatory and procoagulant stimuli increases expression of surface cell‐adhesion molecules (CAMs), releases endothelium‐derived microvesicles (MV) into the circulation, and increases permeability of the blood‐brain barrier (BBB). This study evaluated characteristics of MV released from human brain microvascular endothelial cells (HBMEC) following stimulation with proinflammatory or procoagulant stimuli and examined their effect on monolayer permeability. Methods Cultured HBMECs from age‐matched male and female donors were treated for 24 hours with medium supplemented with tumor necrosis factor alpha (TNF α , 20 ng/mL), thrombin (THR, 2 U/mL), or vehicle (control). MVs released into the medium were isolated by differential centrifugation, labeled with annexin V together with antibodies against PECAM‐1, ICAM‐1, E‐selectin, integrin aV, or MCAM, and then analyzed by digital flow cytometry. Permeability (mg/mL FITC‐dextran) of the HBMEC monolayer in response to MV treatment was quantified by fluorescence microplate assay of passage of FITC‐dextran across monolayer cells cultured on microporous supports. Results Fewer specific antigen‐positive MV were released from unstimulated male compared to female HBMECs. TNF a , but not THR induced early‐stage apoptosis; determined by fluorogenic Caspase‐3 assay in the HBMEC monolayers. TNF a induced release of all MV subtypes from male cells, whereas only integrin aV, ICAM‐1 and E‐selectin positive MVs were released from female cells. THR increased release of PECAM‐1, ICAM‐1, and MCAM positive MVs from male cells, but did not increase release of MV in female cells. After 24 hours exposure to MV (2,500 MV/mL) derived from TNF a ‐treated female cells, permeability increased by 17%. Permeabiity was not increased when female cells were exposed to THR‐generated MV. Conclusions These results indicate that: 1) inflammatory and procoagulant stimuli release a different array of MV subtypes from male and female HBMECs; 2) specific stimuli‐derived MVs can modify HMBMEC permeability. Support or Funding Information (Supported by NIH P50 AG44170 and the Mayo Clinic Fnd.).

Objective Preeclampsia (PE) is a hypertensive pregnancy disorder that represents a sex‐specific risk factor for future cardiovascular disease in affected women. This study evaluated the associations of a history of PE, conventional cardiovascular risk factors and vascular activation (defined by activation of blood elements and blood‐borne microvesicles (MV)) with carotid intima‐media thickness (CIMT) in menopausal women. Methods Caucasian women residents of Olmsted County, MN who delivered between 1976 and 1982 were identified from review of their medical records and matched for parity and age at index birth: 40 with a history of preeclampsia (PE) and 40 with a history of normotensive pregnancy (NP). Blood clinical chemistries and 38 measures of intravascular activation including differential cell counts, platelet aggregation and secretion, cell‐cell interactions, and blood‐borne MV were measured in venous blood. CIMT was measured by B‐mode ultrasound. The study was approved by the IRB at Mayo Clinic and all women gave written informed consent. Results Women averaged 60 years of age at the time of testing. CIMT was greater in the PE [0.80 mm (0.75, 0.85); median (25th, 75th percentile)] compared to the NP [0.73 mm (0.70, 0.78)] group (P=0.004). Body mass index, waist circumference, fasting insulin, high‐sensitive C‐reactive protein and present day hypertension were greater in the PE group. After adjusting for potential confounding factors, the odds of having a higher CIMT value was more than 3‐fold higher for women with a history of PE [OR 3.46 (1.38, 8.68); P=0.008]. Principal components (PC) analysis identified 7 components that accounted for 63% of the variability in measures of intravascular activation. The global test for association of intravascular activation with CIMT (P=0.009) was only significant among women with a history of NP. PC#4, which conveyed measures of whole blood platelet aggregation and platelet interactions with granulocytes and monocytes, positively associated with CIMT in the overall group after adjustment for PE status (partial ρ=0.290; P=0.009). PC#6, consisting of measures of platelet activation with platelet count and interactions between monocytes and the vascular endothelium, also showed a significant interaction with pregnancy history (P=0.014). Conclusion A history of preeclampsia accompanied by metabolic and pro‐coagulant/‐inflammatory intravascular cellular activation contributes to progression of CIMT in menopausal women. Support or Funding Information This work was funded by grants from the NIH AG44170, AG034676, UL1 TR000135 and the Mayo Foundation.

American Heart Association estimates the prevalence of valvular heart disease to be 2.5% in the United States. Biological heart valve replacements, such as glutaraldehyde‐fixed bovine pericardium (BP), are considered the current standard of care. The NHLBI xenotransplantation working group identified xenoantigenicity as the major barrier to expanding use of such xenogeneic tissues. Previous research has utilized an immunoproteomic approach based on two‐dimensional western blots to identify a small number of BP xenoantigens, which is time consuming and technically challenging. These limitations have resulted in an ever increasing use of shotgun proteomic approaches due to their superior throughput and reproducibility. However, traditional Liquid Chromatography‐Mass Spectrometry (LC‐MS) fails to separate proteins based on their antigenicity, and therefore it is impossible to determine which identified proteins are antigenic versus not. We hypothesized that an affinity chromatography method utilizing poly‐polyclonal serum would bridge this gap and represent an innovative shotgun proteomic antigen identification approach. Using affinity chromatography rabbit IgG antibodies were isolated from whole serum with Protein A HP SpinTrap (GE Healthcare). IgG capture was confirmed by serum protein electrophoresis and ELISA. Two types of antibody affinity columns were generated, with naive serum (D0) or serum from rabbits immunized with bovine pericardium (D84). Bovine pericardial protein extracts were run through both affinity columns, allowing for the specific capture of antigens, which were later eluted and collected. To confirm specificity of antigen capture, eluants were subjected to western blot, and probed with D84 serum. Affinity enriched antigenic proteins were identified by LC‐MS/MS, with statistical comparisons made between D0 and D84. This approach identified 133 putative antigenic proteins that were enriched on D84 compared to D0 columns. Ten of these antigens corresponded to previously published BP xenoantigens. Of the remaining 123 previously unidentified antigens, 30 have been indicated to be immunogenic in other fields such as cancer and autoimmunity. This method was then applied to three humans who had been implanted with bovine pericardial heart valves. Surprisingly, 300 to 500 proteins were identified from patient columns. Between 57 to 79% of the identified proteins were shared among the three individuals, as well as almost all of the proteins identified in the rabbit model were also present in the human. This work therefore represents the first high throughput method of antigen identification that can now be used to monitor currently implanted patients as well as inform the development of BP‐based biomaterials in the future. Support or Funding Information Research supported by grant number R01HL115205 from the National Heart Lung and Blood Institute (NHLBI) at the National Institutes of Health (NIH) and grant number 5T32OD010931‐10 from the NIH.

Ultrasound has been used more frequently in the anatomical sciences to reinforce core anatomy concepts in the classroom and introduce commonly applied imaging technologies encountered in a clinical setting. Interprofessional Education (IPE) is being incorporated into health sciences training as a learning model for real world interactions. The primary objective of the current study was to determine the impact of an IPE ultrasound curriculum on students' anatomy and ultrasound knowledge, as well as attitudes towards interprofessional collaboration. We hypothesized that students who participated in an IPE experience would have improved recall of anatomical and ultrasound concepts as well as improved attitudes and perceptions towards IPE when compared to students who did not participate in an IPE session. First year medical students (MD, n = 40) and first year physical therapy students (PT, n = 25) were randomly assigned to PT‐only, MD‐only, or mixed PT‐MD ultrasound instruction groups studying the shoulder. Students were assessed using an anatomy and ultrasound knowledge test and University of the West of England Interprofessional Questionnaire (UWEIPQ) prior to and following the session. The results of this study suggest that while ultrasound instruction significantly improves ultrasound post‐test scores when compared to pre‐test scores regardless of group assignment (PT‐only: p < 0.001; MD‐only: p = 0.007; PT‐MD: p < 0.001), learning in an interprofessional PT‐MD group did not significantly impact knowledge recall of ultrasound concepts when compared to non‐IPE groups. Interestingly, students in PT‐MD groups had significantly higher anatomy post‐test scores when compared to the MD‐only groups (PT‐MD post‐test = 93.2%; MD‐only post‐test = 84.1%; p = 0.041), but not when compared to the PT‐only groups. Additionally, the results of the UWEIPQ are consistent with the impression that students who participate in an IPE experience are more likely to be cognizant of inherent biases in the interactions between different health professionals as well as demonstrate increased confidence in their interprofessional relationships. In conclusion, our study reinforces that IPE programs should quantify knowledge recall in order to assess the effectiveness of a specific program. Furthermore, such endeavors should assess important competencies including communication, teamwork, and interdisciplinary respect that are necessary to succeed in a multidisciplinary health care team. Support or Funding Information Department of Anatomy, Mayo Clinic College of Medicine and Science, Mayo Clinic, Rochester, MN; Social Science and Humanities Research Council, Government of Canada

Enzyme catalytic power and specificity derive from dynamic interactions between enzymes and their substrates. While considerable effort has been devoted to understanding how enzyme conformational dynamics can affect catalysis, the importance of conformational dynamics within protein substrates has been overlooked. Proteases are ubiquitous enzymes that catalyze the hydrolysis of peptide bonds within protein substrates; they have served as key model enzymes for studying the molecular basis for catalysis and specificity. Recent work from our research group, focusing on trypsins and chymotrypsins as model proteolytic enzymes, reveals that differing conformational dynamics in otherwise similar protein substrates can profoundly impact proteolysis. In this talk, I will present some of our recent findings, integrating evidence from crystal structures, molecular dynamics simulations, and enzyme kinetics studies, which implicate flexibility and conformational motions of protease substrates as critical determinants of proteolysis. Our studies suggest that specific substrate conformational dynamics have evolved to regulate biological proteolytic events. More generally, our work suggests that we must look beyond enzymes, and examine substrates also, to fully appreciate the importance of protein dynamics in enzyme catalysis. Support or Funding Information Supported by NIH grant R01CA154387.

In modern medical curricula, anatomists share responsibility for training the next generation of health care providers. As expectations for medical professionals continue to evolve, anatomy teachers are strategically positioned to support students' acquisition of the core anatomy knowledge together with skills and attitudes necessary to produce caring and effective health care providers. Anatomists must ensure that learners not only possess the necessary breath of knowledge in anatomical sciences but also skills such as leadership, teamwork, communication and professionalism among others. To attain this, anatomy curricula need to follow a path of authentic learning in which students are expected to exercise higher levels of thinking and clinical reasoning through discovery and inquiry. Learning‐by‐doing is the most effective learning strategy not only in the laboratory and interactive classroom, but also in the real‐life environment of imaging technologies. To ensure the success of this strategy, students must receive frequent performance feedback to advance their learning and capability for improvement. When anatomists embrace the maxim “the needs of the patient come first,” the learning becomes as much social as cognitive, as much solid as intangible, and becomes entwined with judgment and exploration just as it is in the real clinical world.