Autologous veins are the most widely used grafts for bypassing small arteries in coronary and peripheral arterial occlusive diseases. However, they have limited availability and cause donor-site morbidity. Here, we report a direct comparison of acellular biodegradable synthetic grafts and autologous veins as interposition grafts of rat carotid arteries, which is a good model for clinically relevant small arteries. Notably, extensive but transient infiltration of circulating monocytes at day 14 in synthetic grafts leads to a quickly-resolved inflammation and arterial-like tissue remodeling. The vein graft exhibits a similar inflammation phase except the prolonged presence of inflammatory monocytes. The walls of the remodeled synthetic graft contain many circumferentially aligned contractile non-proliferative smooth muscle cells (SMCs), collagen and elastin. In contrast, the walls of the vein grafts contain disorganized proliferating SMCs and thicken over time, suggesting the onset of stenosis. At 3 months, both grafts have a similar patency, extracellular matrix composition, and mechanical properties. Furthermore, synthetic grafts exhibit recruitment and re-orientation of newly synthesized collagen fibers upon mechanical loading. To our knowledge, this is the first demonstration of a biodegradable synthetic vascular graft with a performance similar to an autologous vein in small artery grafting.

Rational drug design against a determined target (disease, pathway, or protein) is the main strategy in drug discovery. However, regardless of the main strategy, chemists really wonder how to maximize the utility of their new compounds by drug repositioning them as clinical drug candidates in drug discovery. In this study, we started our drug discovery "from curiosity in the chemical structure of a drug scaffold itself" rather than "for a specific target". As a new drug scaffold, anomeric diarylamino cyclic aminal scaffold 1, was designed by combining two known drug scaffolds (diphenylamine and the most popular cyclic ether, tetrahydropyran/tetrahydrofuran) and synthesized through conventional Brønsted acid catalysis and metal-free α-C(sp3)-H functionalized oxidative cyclization. To identify the utility of the new scaffold 1, it was investigated through 2D and 3D similarity screening and chemocentric target prediction. The predicted proteins were investigated by an experimental assay. The scaffold 1 was reported to have an antineuroinflammatory agent to reduce NO production, and compound 10 concentration-dependently regulated the expression level of IL-6, PGE-2, TNF-α, ER-β, VDR, CTSD, and iNOS, thus exhibiting neuroprotective activity.

Heart attack is a global health problem that leads to significant morbidity, mortality, and health care burden. Adult human hearts have very limited regenerative capability after injury. However, evolutionarily primitive species generally have higher regenerative capacity than mammals. The extracellular matrix (ECM) may contribute to this difference. Mammalian cardiac ECM may not be optimally inductive for cardiac regeneration because of the fibrotic, instead of regenerative, responses in injured adult mammalian hearts. Given the high regenerative capacity of adult zebrafish hearts, we hypothesize that decellularized zebrafish cardiac ECM (zECM) made from normal or healing hearts can induce mammalian heart regeneration. Using zebrafish and mice as representative species of lower vertebrates and mammals, we show that a single administration of zECM, particularly the healing variety, enables cardiac functional recovery and regeneration of adult mouse heart tissues after acute myocardial infarction. zECM-treated groups exhibit proliferation of the remaining cardiomyocytes and multiple cardiac precursor cell populations and reactivation of ErbB2 expression in cardiomyocytes. Furthermore, zECM exhibits pro-proliferative and chemotactic effects on human cardiac precursor cell populations in vitro. These contribute to the structural preservation and correlate with significantly higher cardiac contractile function, notably less left ventricular dilatation, and substantially more elastic myocardium in zECM-treated hearts than control animals treated with saline or decellularized adult mouse cardiac ECM. Inhibition of ErbB2 activity abrogates beneficial effects of zECM administration, indicating the possible involvement of ErbB2 signaling in zECM-mediated regeneration. This study departs from conventional focuses on mammalian ECM and introduces a new approach for cardiac tissue regeneration.

BackgroundPulmonary hypertension (PH) results in increased right ventricular (RV) afterload and ventricular remodeling. Sacubitril/valsartan (sac/val) is a dual acting drug, composed of the neprilysin inhibitor sacubitril and the angiotensin receptor blocker valsartan, that has shown promising outcomes in reducing the risk of death and hospitalization for chronic systolic left ventricular heart failure. In this study, we aimed to examine if angiotensin receptor-neprilysin inhibition using sac/val attenuates RV remodeling in PH.Methods and ResultsRV pressure overload was induced in Sprague-Dawley rats via banding the main pulmonary artery. Three different cohorts of controls, placebo-treated PH, and sac/val-treated PH were studied in a 21-day treatment window. Terminal invasive hemodynamic measurements, quantitative histological analysis, biaxial mechanical testing, and constitutive modeling were employed to conduct a multiscale analysis on the effects of sac/val on RV remodeling in PH. Sac/val treatment decreased RV maximum pressures (29% improvement, P=0.002), improved RV contractile (30%, P=0.012) and relaxation (29%, P=0.043) functions, reduced RV afterload (35% improvement, P=0.016), and prevented RV-pulmonary artery uncoupling. Furthermore, sac/val attenuated RV hypertrophy (16% improvement, P=0.006) and prevented transmural reorientation of RV collagen and myofibers (P=0.011). The combined natriuresis and vasodilation resulting from sac/val led to improved RV biomechanical properties and prevented increased myofiber stiffness in PH (61% improvement, P=0.032).ConclusionsSac/val may prevent maladaptive RV remodeling in a pressure overload model via amelioration of RV pressure rise, hypertrophy, collagen, and myofiber reorientation as well as tissue stiffening both at the tissue and myofiber level.

In vitro cell experiments have been performed to detect and monitor the upregulation of intercellular adhesion molecule-1 (ICAM-1) and E-selectin simultaneously by photoacoustic molecular imaging (PMI). Human umbilical vein endothelial cells (HUVECs) were grown on gelatin-coated glass slides and stimulated with inflammatory cytokines to induce the expression of the inflammatory biomarkers, ICAM-1 and E-selectin. Gold nanorods (GNRs) of aspect ratio (AR) 1:3 with absorption centered at 715 nm conjugated to anti-ICAM-1 antibody and GNRs of AR 1:3.5 with absorption centered at 800 nm conjugated to anti-E-selectin were exposed to HUVECs with different stimulation conditions. A focused high frequency ultrasonic transducer (60 MHz, f/1.5) was used to scan the photoacoustic (PA) signal over the top surface of the cell containing slides. Averaged PA signal intensity from the stimulated cells was about 3 folds higher (~10 dB) compared to the un-stimulated cells for both ICAM-1 and E-selectin. The strong binding of GNRs to the stimulated HUVEC cells was evidenced by fluorescence imaging. Exposure of HUVEC cells to GNRs conjugated to isotype control antibodies confirms a low level non-specific binding. Also, at 0, 2, 6, and 24 hours after inflammatory stimulation, the HUVECs were exposed to GNRs conjugated anti-ICAM-1 antibody and anti-E-selectin antibody. PA intensity at each stage of inflammation compares well with fluorescence imaging and rt-PCR quantification.

In contrast to short-lived neutrophils, macrophages display persistent presence in the lung of animals after pulmonary exposure to carbon nanotubes. While effective in the clearance of bacterial pathogens and injured host cells, the ability of macrophages to "digest" carbonaceous nanoparticles has not been documented. Here, we used chemical, biochemical, and cell and animal models and demonstrated oxidative biodegradation of oxidatively functionalized single-walled carbon nanotubes via superoxide/NO* → peroxynitrite-driven oxidative pathways of activated macrophages facilitating clearance of nanoparticles from the lung.

Mechanical and structural changes of right ventricular (RV) in response to pulmonary hypertension (PH) are inadequately understood. While current standard biaxial testing provides information on the mechanical behavior of RV tissues using surface markers, it is unable to fully assess structural and mechanical properties across the full tissue thickness. In this study, the mechanical and structural properties of normotensive and pulmonary hypertension right ventricular (PHRV) myocardium through its full thickness were examined using mechanical testing combined with 3D ultrasound speckle tracking (3D-UST). RV pressure overload was induced in Sprague-Dawley rats by pulmonary artery (PA) banding. The second Piola-Kirchhoff stress tensors and Green-Lagrangian strain tensors were computed in the RV myocardium using the biaxial testing combined with 3D-UST. A previously established non-linear curve-fitting algorithm was applied to fit experimental data to a Strain Energy Function (SEF) for computation of myofiber orientation. The fiber orientations obtained by the biaxial testing with 3D-UST compared well with the fiber orientations computed from the histology. In addition, the re-orientation of myofiber in the right ventricular free wall (RVFW) along longitudinal direction (apex-to-outflow-tract direction) was noticeable in response to PH. For normotensive RVFW samples, the average fiber orientation angles obtained by 3D-UST with biaxial test spiraled from 20° at the endo-cardium to -42° at the epi-cardium (Δ = 62°). For PHRV samples, the average fiber orientation angles obtained by 3D-UST with biaxial test had much less spiral across tissue thickness: 3° at endo-cardium to -7° at epi-cardium (Δ = 10°, P<0.005 compared to normotensive).

There is a growing body of research on the neural control of immunity and inflammation. However, it is not known whether the nervous system can regulate the production of inflammatory myeloid cells from hematopoietic progenitor cells in disease conditions. Myeloid cell numbers in diabetic patients were strongly correlated with plasma concentrations of norepinephrine, suggesting the role of sympathetic neuronal activation in myeloid cell production. The spleens of diabetic patients and mice contained higher numbers of tyrosine hydroxylase (TH)-expressing leukocytes that produced catecholamines. Granulocyte macrophage progenitors (GMPs) expressed the β2 adrenergic receptor, a target of catecholamines. Ablation of splenic sympathetic neuronal signaling using surgical, chemical, and genetic approaches diminished GMP proliferation and myeloid cell development. Finally, mice lacking TH-producing leukocytes had reduced GMP proliferation, resulting in diminished myelopoiesis. Taken together, our study demonstrates that catecholamines produced by leukocytes and sympathetic nerve termini promote GMP proliferation and myeloid cell development.

Acute kidney injury (AKI) is a risk factor for the development of chronic kidney disease (CKD). One mechanism for this phenomenon is renal microvascular rarefaction and subsequent chronic impairment in perfusion. However, diagnostic tools to monitor the renal microvasculature in a noninvasive and quantitative manner are still lacking. Ultrasound super-resolution imaging is an emerging technology that can identify microvessels with unprecedented resolution. Here, we applied this imaging technique to identify microvessels in the unilateral ischemia-reperfusion injury mouse model of AKI-to-CKD progression in vivo. Kidneys from 21 and 42 day post- ischemia-reperfusion injury, the contralateral uninjured kidneys, and kidneys from sham-operated mice were examined by ultrasound super-resolution and histology. Renal microvessels were successfully identified by this imaging modality with a resolution down to 32 μm. Renal fibrosis was observed in all kidneys with ischemia-reperfusion injury and was associated with a significant reduction in kidney size, cortical thickness, relative blood volume, and microvascular density as assessed by this imaging. Tortuosity of the cortical microvasculature was also significantly increased at 42 days compared to sham. These vessel density measurements correlated significantly with CD31 immunohistochemistry (R2=0.77). Thus, ultrasound super-resolution imaging provides unprecedented resolution and is capable of noninvasive quantification of renal vasculature changes associated with AKI-to-CKD progression in mice. Hence, this technique could be a promising diagnostic tool for monitoring progressive kidney disease.

Pulmonary arterial hypertension (PAH) is a disease resulting in increased right ventricular (RV) afterload and RV remodeling. PAH results in altered RV structure and function at different scales from organ-level hemodynamics to tissue-level biomechanical properties, fiber-level architecture, and cardiomyocyte-level contractility. Biomechanical analysis of RV pathophysiology has drawn significant attention over the past years and recent work has found a close link between RV biomechanics and physiological function. Building upon previously developed techniques, biomechanical studies have employed multi-scale analysis frameworks to investigate the underlying mechanisms of RV remodeling in PAH and effects of potential therapeutic interventions on these mechanisms. In this review, we discuss the current understanding of RV structure and function in PAH, highlighting the findings from recent studies on the biomechanics of RV remodeling at organ, tissue, fiber, and cellular levels. Recent progress in understanding the underlying mechanisms of RV remodeling in PAH, and effects of potential therapeutics, will be highlighted from a biomechanical perspective. The clinical relevance of RV biomechanics in PAH will be discussed, followed by addressing the current knowledge gaps and providing suggested directions for future research.

Influenza virus poses a recurring threat to public health and infects many populations in annual waves of generally unpredictable magnitude and timing. We aimed to detect the arrival and estimate the case magnitude of seasonal influenza A in urban New York City college dormitory buildings. Our wastewater-based surveillance (WBS) program measured viral RNA in the sewage outflow of three dormitories at Barnard College in 2021 and 2022. Wastewater test positivity strongly correlated with New York County clinical cases (Kendall's τ = 0.58). Positive wastewater samples are also associated with campus clinical cases. The 2022 data stand in stark contrast to the 2021 results by revealing the more frequent and earlier presence of influenza A. The increase in positive tests is significant (P < 0.01). It is further noteworthy that positive samples were not evenly distributed among buildings. Surveillance additionally identified the influenza A H3 subtype but did not detect any influenza B. We also systematically analyzed our viral purification protocol to identify in which fraction influenza can be found. While virus can be found in solid fractions, a substantial quantity remains in the final liquid fraction. Our work focuses on individual buildings rather than larger sewersheds because buildings may localize interseasonal influenza variation to specific subpopulations. Our results highlight the potential value of building-level WBS in measuring influenza incidence to help guide public health intervention.IMPORTANCESeasonal influenza remains a major public health burden. We monitored influenza A in dormitory wastewater of a New York City college in 2021 and 2022. Longitudinal samples acquired over consecutive years allowed measurement of individual buildings between seasons. We uncovered building-level changes in the magnitude and timing of test positivity concordant with clinical cases. Surveillance also localized the heterogeneity of influenza variation during the large 2022 seasonal surge. The ability to detect such changes could be leveraged as part of a public health response.

Functional electrical stimulation (FES) is a potential neurorehabilitative intervention to enable functional movements in persons with neurological conditions that cause mobility impairments. However, the quick onset of muscle fatigue during FES is a significant challenge for sustaining the desired functional movements for more extended periods. Therefore, a considerable interest still exists in the development of sensing techniques that reliably measure FES-induced muscle fatigue. This study proposes to use ultrasound (US) imaging-derived echogenicity signal as an indicator of FES-induced muscle fatigue. We hypothesized that the US-derived echogenicity signal is sensitive to FES-induced muscle fatigue under isometric and dynamic muscle contraction conditions. Eight non-disabled participants participated in the experiments, where FES electrodes were applied on their tibialis anterior (TA) muscles. During a fatigue protocol under either isometric and dynamic ankle dorsiflexion conditions, we synchronously collected the isometric dorsiflexion torque or dynamic dorsiflexion angle on the ankle joint, US echogenicity signals from TA muscle, and the applied stimulation intensity. The experimental results showed an exponential reduction in the US echogenicity relative change (ERC) as the fatigue progressed under the isometric (R2=0.891±0.081) and dynamic (R2=0.858±0.065) conditions. The experimental results also implied a strong linear relationship between US ERC and TA muscle fatigue benchmark (dorsiflexion torque or angle amplitude), with R2 values of 0.840±0.054 and 0.794±0.065 under isometric and dynamic conditions, respectively. The findings in this study indicate that the US echogenicity signal is a computationally efficient signal that strongly represents FES-induced muscle fatigue. Its potential real-time implementation to detect fatigue can facilitate an FES closed-loop controller design that considers the FES-induced muscle fatigue.

Maneuverable microswimmers/microdrones that navigate in hard-to-reach spaces inside human bodies hold a great potential for various biomedical applications. Acoustically actuated microswimmers have already demonstrated feasibility. However, for eventual translation of this technology, a robust 3-D tracking strategy for the microswimmer is particularly required. This paper presents our lab-designed 3-D ultrasound tracking system for real-time tracking of an acoustically actuated 3-D swimming microdrone. The ultrasound tracking system utilizing two ultrasound probes, a step motor and a host controller, was built to track the 3-D arbitrary motion of the microdrone in real-time. The performance of tracking was evaluated in the benchtop experiments by comparing the reconstructed trajectories with synchronized camera recordings. The ultrasound tracking system showed high reliability, with an average error of less than 0.3 mm across six different trials when compared to camera tracking. The results demonstrated the capability of our lab-designed 3-D ultrasound tracking system in accurately tracking the undetermined motion of the acoustic actuated 3-D swimming microdrone in real-time. The developed tracking system holds promise as a potential approach for biomedical applications and could pave the way for future clinical translation of the microswimmer technology.

Traditional ultrasound imaging techniques are limited in spatial resolution to visualize angiogenic vasa vasorum that is considered as an important marker for atherosclerotic plaque progression and vulnerability. The recently introduced super-resolution imaging technique based on microbubble center localization has shown potential to achieve unprecedented high spatial resolution beyond the acoustic diffraction limit. However, a major drawback of the current super-resolution imaging approach is low temporal resolution because it requires a large number of imaging frames. In this study, a new imaging sequence and signal processing approach for super-resolution ultrasound imaging are presented to improve temporal resolution by employing deconvolution and spatio-temporal-interframe-correlation based data acquisition. In vivo feasibility of the developed technology is demonstrated and evaluated in imaging vasa vasorum in the rabbit atherosclerosis model. The proposed method not only identifies a tiny vessel with a diameter of 41 μm, 5 times higher spatial resolution than the acoustic diffraction limit at 7.7 MHz, but also significantly improves temporal resolution that allows for imaging vessels over cardiac motion.

Right ventricular (RV) remodeling and longitudinal fiber reorientation in the setting of pulmonary hypertension (PH) affects ventricular structure and function, eventually leading to RV failure. Characterizing the kinematics of myocardial fibers helps better understanding the underlying mechanisms of fiber realignment in PH. In the current work, high-frequency ultrasound imaging and structurally-informed finite element (FE) models were employed for an exploratory evaluation of the stretch-induced kinematics of RV fibers. Image-based experimental evaluation of fiber kinematics in porcine myocardium revealed the capability of affine assumptions to effectively approximate myofiber realignment in the RV free wall. The developed imaging framework provides a noninvasive modality to quantify transmural RV myofiber kinematics in large animal models. FE modeling results demonstrated that chronic pressure overload, but not solely an acute rise in pressures, results in kinematic shift of RV fibers towards the longitudinal direction. Additionally, FE simulations suggest a potential protective role for concentric hypertrophy (increased wall thickness) against fiber reorientation, while eccentric hypertrophy (RV dilation) resulted in longitudinal fiber realignment. Our study improves the current understanding of the role of different remodeling events involved in transmural myofiber reorientation in PH. Future experimentations are warranted to test the model-generated hypotheses.

Evidence of the clinical impact of programmed death-ligand 1 (PD-L1) expression in small cell lung cancer (SCLC) is scarce and conflicting, even though atezolizumab became the first PD-L1 inhibitor approved by the US Food and Drug Administration (FDA) in recent years for the initial treatment of extensive-stage (ES)-SCLC.

Myocardial infarction (MI) causes myocardial necrosis, triggers chronic inflammatory responses, and leads to pathological remodeling. Controlled delivery of a combination of angiogenic and immunoregulatory proteins may be a promising therapeutic approach for MI. We investigated the bioactivity and therapeutic potential of an injectable, heparin-based coacervate co-delivering an angiogenic factor, fibroblast growth factor-2 (FGF2), and an anti-inflammatory cytokine, Interleukin-10 (IL-10) in a spatially and temporally controlled manner. Coacervate delivery of FGF2 and IL-10 preserved their bioactivities on cardiac stromal cell proliferation in vitro. Upon intramyocardial injection into a mouse MI model, echocardiography revealed that FGF2/IL-10 coacervate treated groups showed significantly improved long-term LV contractile function and ameliorated LV dilatation. FGF2/IL-10 coacervate substantially augmented LV myocardial elasticity. Additionally, FGF2/IL-10 coacervate notably enhanced long-term revascularization, especially at the infarct area. In addition, coacervate loaded with 500 ng FGF2 and 500 ng IL-10 significantly reduced LV fibrosis, considerably preserved infarct wall thickness, and markedly inhibited chronic inflammation at the infarct area. These results indicate that FGF2/IL-10 coacervate has notably greater therapeutic potential than coacervate containing only FGF2. Overall, our data suggest therapeutically synergistic effects of FGF-2/IL-10 coacervate, particularly coacervate with FGF2 and 500 ng IL-10, for the treatment of ischemic heart disease.

The objective of this study was to evaluate the long-term performance of cell-free vascular grafts made from a fast-degrading elastic polymer. We fabricated small arterial grafts from microporous tubes of poly(glycerol sebacate) (PGS) reinforced with polycaprolactone (PCL) nanofibers on the outer surface. Grafts were interpositioned in rat abdominal aortas and characterized at 1 year post-implant. Grafts remodeled into "neoarteries" (regenerated arteries) with similar gross appearance to native rat aortas. Neoarteries mimic arterial tissue architecture with a confluent endothelium and media and adventita-like layers. Patent vessels (80%) showed no significant stenosis, dilation, or calcification. Neoarteries contain nerves and have the same amount of mature elastin as native arteries. Despite some differences in matrix organization, regenerated arteries had similar dynamic mechanical compliance to native arteries in vivo. Neoarteries responded to vasomotor agents, albeit with different magnitude than native aortas. These data suggest that an elastic vascular graft that resorbs quickly has potential to improve the performance of vascular grafts used in small arteries. This design may also promote constructive remodeling in other soft tissues.

Healthy aging has been associated with alterations in pulmonary vascular and right ventricular (RV) hemodynamics, potentially leading to RV remodeling. Despite the current evidence suggesting an association between aging and alterations in RV function and higher prevalence of pulmonary hypertension in the elderly, limited data exist on age-related differences in RV structure and biomechanics. In this work, we report our preliminary findings on the effects of healthy aging on RV structure, function, and biomechanical properties. Hemodynamic measurements, biaxial mechanical testing, constitutive modeling, and quantitative transmural histological analysis were employed to study two groups of male Sprague-Dawley rats: control (11 weeks) and aging (80 weeks). Aging was associated with increases in RV peak pressures (+17%, p = 0.017), RV contractility (+52%, p = 0.004), and RV wall thickness (+38%, p = 0.001). Longitudinal realignment of RV collagen (16.4°, p = 0.013) and myofibers (14.6°, p = 0.017) were observed with aging, accompanied by transmural cardiomyocyte loss and fibrosis. Aging led to increased RV myofiber stiffness (+141%, p = 0.003), in addition to a bimodal alteration in the biaxial biomechanical properties of the RV free wall, resulting in increased tissue-level stiffness in the low-strain region, while progressing into decreased stiffness at higher strains. Our results demonstrate that healthy aging may modulate RV remodeling via increased peak pressures, cardiomyocyte loss, fibrosis, fiber reorientation, and altered mechanical properties in male Sprague-Dawley rats. Similarities were observed between aging-induced remodeling patterns and those of RV remodeling in pressure overload. These findings may help our understanding of age-related changes in the cardiovascular fitness and response to disease.