Injection Of Microspheres Research Articles

Development of puerarin-loaded poly(lactic acid) microspheres for sustained ocular delivery: In vitro/vivo evaluation

Diabetic retinopathy, an ocular complication of diabetes, is an important cause of blindness in adults. Puerarin is considered to have promising potential for clinical use in treating diabetic retinopathy. In this study, we designed a novel puerarin-loaded poly(lactic acid) sustained-release microspheres suitable for ocular administration, and we assessed itsin vitro and in vivo properties. The preparation of puerarin-loaded microspheres was optimized by Box-Behnken response surface design. The encapsulation efficiency and drug loading of microspheres were 35.71% and 3.85%, respectively. The microspheres exhibited good dispersion and high safety, making it suitable for ocular drug delivery. In vitro release demonstrated that microspheres had a well-sustained release effectiveness, and its release behavior complied with the zero-order kinetic characteristics. The results of ocular tissue distribution revealed that the CmaxandAUC0-∞ of the microspheres group in the retina and choroid were considerably higher than those of the solution group and the intravenous injection group. This research revealed that intravitreal injection of microspheres can significantly prolong the half-life of puerarin in eye tissues and achieve sustained drug release. Therefore, intravitreal injection of microspheres has positive implications for the treatment of diabetic retinopathy.

Metabolic and Proteomic Profiling of Coronary Microvascular Dysfunction: Insights from Rat Models

Coronary microvascular dysfunction (CMD) represents a principal etiological factor in ischemic heart disease. Nonetheless, a considerable subset of CMD patients experiences diagnostic delays attributable to the inadequacy of current diagnostic methodologies; which in turn results in deferred therapeutic interventions and elevated mortality rates. This study seeks to elucidate the distinct metabolic profile associated with CMD in rat models and to identify specific diagnostic markers that could enhance the diagnostic accuracy for CMD. In this study, 18 Wistar rats were randomly allocated into two groups: the sham group and the CMD group. The CMD group received injections of embolic microspheres into the left ventricle to establish a CMD model. Subsequently, non-targeted metabolomics and acetylated proteomics analyses were conducted. Machine-learning techniques were employed to identify the co-diagnostic markers of the disease. This study identified 53 key proteins through differential expression proteins (DEPs) and modular proteins analysis. Subsequently, four core proteins (Emc1; Ank1; Fbln2; and Hp) were determined as diagnostic markers for CMD using lasso regression, support vector machine, and random forest methodologies. Receiver operating characteristic curve analysis further demonstrated robust diagnostic performance. Gene ontology and kyoto encyclopedia of genes and genome enrichment analyses indicated that the DEPs were predominantly associated with metabolic pathways. Ultimately, the integrative analysis of proteomics and metabolomics suggested that the central metabolic mechanism underlying CMD pathogenesis may be linked to the tricarboxylic acid cycle. This study revealed specific changes in the proteomic and metabolic profiles of CMD rats and identified four diagnostic markers, which are proteins and metabolites that could be potential diagnostic biomarkers for CMD.

Quantitative CT imaging and radiation-absorbed dose estimations of 166Ho microspheres: paving the way for clinical application

BackgroundMicrobrachytherapy enables high local tumor doses sparing surrounding tissues by intratumoral injection of radioactive holmium-166 microspheres (166Ho-MS). Magnetic resonance imaging (MRI) cannot properly detect high local Ho-MS concentrations and single-photon emission computed tomography has insufficient resolution. Computed tomography (CT) is quicker and cheaper with high resolution and previously enabled Ho quantification. We aimed to optimize Ho quantification on CT and to implement corresponding dosimetry.MethodsTwo scanners were calibrated for Ho detection using phantoms and multiple settings. Quantification was evaluated in five phantoms and seven canine patients using subtraction and thresholding including influences of the target tissue, injected amounts, acquisition parameters, and quantification volumes. Radiation-absorbed dose estimation was implemented using a three-dimensional 166Ho specific dose point kernel generated with Monte Carlo simulations.ResultsCT calibration showed a near-perfect linear relation between radiodensity (HU) and Ho concentrations for all conditions, with differences between scanners. Ho detection during calibration was higher using lower tube voltages, soft-tissue kernels, and without a scanner detection limit. The most accurate Ho recovery in phantoms was 102 ± 11% using a threshold of mean tissue HU + (2 × standard deviation) and in patients 98 ± 31% using a 100 HU threshold. Thresholding allowed better recovery with less variation and dependency on the volume of interest compared to the subtraction of a single HU reference value. Corresponding doses and histograms were successfully generated.ConclusionCT quantification and dosimetry of 166Ho should be considered for further clinical application with on-site validation using radioactive measurements and intra-operative Ho-MS and dose visualizations.Relevance statementImage-guided holmium-166 microbrachytherapy currently lacks reliable quantification and dosimetry on CT to ensure treatment safety and efficacy, while it is the only imaging modality capable of quantifying high in vivo holmium concentrations.Key PointsLocal injection of 166Ho-MS enables high local tumor doses while sparing surrounding tissue.CT enables imaging-based quantification and radiation-absorbed dose estimation of concentrated Ho in vivo, essential for treatment safety and efficacy.Two different CT scanners and multiple acquisition and reconstruction parameters showed near-perfect linearity between radiodensity and Ho concentration.The most accurate Ho recoveries on CT were 102 ± 11% in five phantoms and 98 ± 31% in seven canine patients using thresholding methods.Dose estimations and volume histograms were successfully implemented for clinical application using a dose point kernel based on Monte Carlo simulations.Graphical

Tibial transverse transport combined with platelet-rich plasma sustained-release microspheres activates the VEGFA/VEGFR2 pathway to promote microcirculatory reconstruction in diabetic foot ulcer

This study proposes to investigate the therapeutic efficacy and mechanism of combining tibial transverse transport (TTT) with platelet-rich plasma (PRP) for diabetic foot ulcer (DFU). The diabetic rabbit model was constructed with Streptozotocin, which was intervened with TTT and PRP. PRP injection combined with TTT significantly promoted vascularisation and enhanced CD31, VEGFA, and VEGFR2 expressions compared to traditional TTT. However, the VEGFR2 inhibitor suppressed these phenomena. In the in vitro injury model, PRP reversed the diminished human umbilical vein endothelial cells (HUVECs) function and vascularisation caused by high-glucose damage. Additionally, PRP reduced inflammation and oxidative stress (approximately 47% ROS level) and enhanced VEGFA and VEGFR2 expression in HUVECs. However, the knockdown of VEGFR2 reversed the effect of PRP. In conclusion, TTT combined with intraosseous flap injection of PRP sustained-release microspheres activated the VEGFA/VEGFR2 pathway to promote microcirculatory reconstruction in DFU. These findings may provide new potential therapeutic strategies for DFU.

Multifunctional injectable microspheres for osteoarthritis therapy via spatiotemporally modulating macrophage polarization and inflammation

Local injection of anti-inflammatory drugs for osteoarthritis emerged as a promising administration in the clinic, and sustained-release dosage forms have great potential for future therapeutic applications. Controlling the response of patients only in the acute inflammatory phase is currently the focus of therapeutic interventions. To relieve acute pain in patients and to improve the long-term prognosis effect of osteoarthritis treatment, we designed a two-pronged approach in this research: an injectable double-layer microsphere containing a “nonsteroidal anti-inflammatory drug - macrophage polarizing factor” was constructed. The results indicated that microspheres could regulate the intra-articular environment by inhibiting local inflammatory cytokine production, promoting macrophage polarization to the M2-phenotype, and increasing the expression of cartilage repair factors. Polymers chosen could govern the biocompatibility of microspheres and control the release sequence of the two drugs. Injection of microspheres into the degenerative articular cavity of rats leads to suppressed inflammation and well-promoted cartilage regeneration.

Cardiovascular Effects of Increasing Positive End-Expiratory Pressure in A Model of Left Ventricular Cardiogenic Shock in Female Pigs.

Cardiogenic shock (CS) presents a medical challenge with limited treatment options. Positive end-expiratory pressure (PEEP) during mechanical ventilation has been linked with clinical benefits in patients with CS. We investigated if increasing PEEP levels could unload the left ventricle (LV) in CS in a large animal model of LV-CS. LV-CS was induced in 26 female pigs (60 kg) by microsphere injections into the left main coronary artery. In one study protocol PEEP was increased (5, 10, and 15 cmH2O) and then reverted (15, 10, 5 cmH2O) in 3-minute intervals. In another protocol PEEP increments with higher granularity were conducted through 3-minute intervals (5, 8, 10, 13, and 15 cmH2O). Hemodynamic measurements were performed at all PEEP levels during the healthy state and LV-CS with LV pressure-volume loops. The primary endpoint was pressure-volume area (PVA). Secondary endpoints included other mechano-energetic parameters and estimates of LV preload and afterload. Cardiac output (CO) decreased significantly in LV-CS from 4.5±1.0 L/min to 3.1±0.9 L/min (P<0.001). Increasing PEEP resulted in lower PVA, demonstrating a 36±3% decrease in the healthy state (P<0.001) and 18±3% in LV-CS (P<0.001) at PEEP 15 cmH2O. These effects were highly reversible when PEEP was returned to 5 cmH2O. While mean arterial pressure declined with higher PEEP, CO remained preserved during LV-CS (P=0.339). Increasing PEEP caused reductions in key measures of LV preload and afterload during LV-CS. Right ventricular stroke work index was decreased with increased PEEP. Despite a minor increase in heart rate (HR) at PEEP levels of 15 cmH2O (71 bpm vs. 75 bpm, p<0.05), total mechanical power expenditure (PVA normalized to HR) decreased at higher PEEP. Applying higher PEEP levels reduced PVA, preserving CO while decreasing MAP. PEEP could be a viable LV unloading strategy if titrated optimally during LV-CS.

Semaglutide Improves Myocardial Perfusion and Performance in a Large Animal Model of Coronary Artery Disease.

Coronary artery disease (CAD) is the leading cause of death worldwide. It imposes an enormous symptomatic burden on patients, leaving many with residual disease despite optimal procedural therapy, and up to 1/3 with debilitating angina amenable neither to procedures, nor to current pharmacologic options. Semaglutide, a glucagon-like peptide 1 agonist originally approved for management of diabetes, has garnered substantial attention for its capacity to attenuate cardiovascular risk. Although subgroup analyses in patients indicate promise, studies explicitly designed to isolate the impact of semaglutide on the sequelae of CAD, independently of comorbid diabetes or obesity, are lacking. Yorkshire swine (n=17) underwent placement of an ameroid constrictor around the left circumflex coronary artery to induce CAD. Oral semaglutide was initiated postoperatively at 1.5 mg and scaled up in 2 weeks to 3 mg in treatment animals (SEM, n=8) for a total of 5 weeks, while control animals (CON, n=9) received no drug. All then underwent myocardial harvest with acquisition of perfusion and functional data using microsphere injection and pressure-volume loop catheterization. Immunoblotting, immunohistochemistry, and immunofluorescence were performed on the most ischemic myocardial segments for mechanistic elucidation. SEM animals exhibited improved left ventricular ejection fraction, both at rest and during rapid myocardial pacing (both p<0.03), accompanied by increased perfusion to the most ischemic myocardial region at rest and during rapid pacing (both p<0.03); reduced perivascular and interstitial fibrosis (both p <0.03); and apoptosis (p=0.008). These changes were associated with increased activation of the endothelial-protective AMPK pathway (p=0.005), coupled with downstream increases in endothelial nitric oxide synthase (p=0.014). This study is the first to reveal the capacity of oral semaglutide to augment cardiac function in the chronically ischemic heart in a highly translational large animal model, likely through AMPK-mediated improvement in endothelial function and perfusion to the ischemic myocardium.

Construction of glaucoma model and comparing eyeball enlargement with myopia in Guinea pig

This study aimed to develop and evaluate a guinea pig model for glaucoma, comparing resultant eyeball enlargement with an existing myopia model. Thirty guinea pigs underwent intracameral injection of magnetic microspheres to induce chronic ocular hypertension (COH). Intraocular pressure (IOP) was systematically monitored, revealing a successful induction of COH in 73.33% of the guinea pigs. The mean IOP increased from a baseline of 18.04 ± 1.33 mmHg, reaching a peak at week 3 (36.31 ± 6.13 mmHg) and remaining elevated for at least 7 weeks. All data are presented as mean ± standard deviation of the mean. Subsequently, detailed assessments were conducted to validate the established glaucoma model. Immunofluorescent staining demonstrated a significant decrease in the density of retinal ganglion cells (RGC) in the glaucoma group. Optic disc excavation and notable thinning of the lamina cribrosa (LC) were observed. The quantity of optic nerve ax·ons in glaucoma group gradually decreased from baseline (44553 ± 3608/mm2) to week 4 (28687 ± 2071/mm2) and week 8 (17977 ± 3697/mm2). Moreover, regarding the global enlargement of eyeballs, both the transverse and longitudinal axis in glaucomatous eyes were found to be significantly larger than that in myopic eyes, particularly in the anterior chamber depth (1.758 ± 0.113 mm vs. 1.151 ± 0.046 mm). These findings indicate distinct patterns of structural changes associated with glaucoma and myopia in the guinea pig model. This guinea pig model holds promise for future research aimed at exploring biomechanical mechanisms, therapeutic interventions, and advancing our understanding of the relationship between glaucoma and myopia.

Gelatin-methacrylate microspheres loaded with tendon-derived stem cells facilitate tendinopathy healing

Tendon injuries are very common in orthopedic practice and can lead to constant pain, disability, and huge financial burden on society. Gelatin methacrylate (GelMA) and tendon-derived stem cells (TDSCs) may be helpful for the treatment of chronic micro-injury disease of the tendons. In vitro, GelMA microspheres were physically evaluated and assessed for their biological effects on TDSCs, including adhesion, proliferation, and ability to differentiate into tendons, and were also analyzed by sequencing at the RNA level and validated for relevant signaling pathways. A rat Achilles tendon microinjury model was used to evaluate the effect of GelMA microspheres combined with TDSCs on tendon repair. GelMA microspheres promoted adhesion, proliferation, and early tendinous differentiation of TDSCs. TDSCs were able to secrete large amounts of extracellular matrix and activate RAS/ERK signaling in the GelMA microenvironment. In vivo, injection of TDSCs-loaded GelMA microspheres promoted repair of Achilles tendon microinjury. GelMA microspheres and TDSCs synergistically promote Achilles tendon regeneration with the involvement of the RAS/ERK signaling pathway.

Proximal and distant expression of growth differentiation factor 15 (GDF15) correlate with neurological deficit following experimental ischemic stroke.

Growth differentiation factor 15 (GDF15) has emerged as a promising biomarker in cerebro-cardiovascular disease, particularly in acute and chronic inflammatory stress situations. However, understanding the origins, targets and functions of GDF15 in clinical situations, such as ischemic stroke, remains a complex challenge. This study aims to assess the sources of GDF15 production following an experimental ischemic stroke. Adult male Wistar rats underwent cerebral embolization through microspheres injection into the left or right internal carotid artery. Two hours post-surgery, GDF15 expression was analyzed in the brain, blood, lungs, liver and heart using quantitative RT-PCR and Western blotting. Stroke model induced large cerebral infarcts accompanied by severe neurological deficits. GDF15 gene expression exhibited a substantial increase in the ipsilateral cortex and cerebellum, with a lesser extent in the contralateral cortex. Regarding GDF15 protein expression, proGDF15 levels were elevated in the 3 aforementioned organs mentioned and the heart. However, the mature form of GDF15 was exclusively present and increased in the heart. Finally, the expression of GDF15 expression was correlated with the neurological deficit score. Our findings suggest that both the GDF15 gene and pro-protein are expressed in the ischemic brain after a stroke, while only its mature form is expressed remotely in in the heart. The impact of increased GDF15 in the heart following a stroke remains to be established. This is particularly relevant in understanding its relationships with poor neurological outcomes, determining whether it may contribute to stroke-induced cardiac dysfunction.

Simplification strategies for a patient-specific CFD model of particle transport during liver radioembolization

BackgroundPatient-specific 3D computational fluid dynamics (CFD) simulations have been used previously to identify the impact of injection parameters (e.g. injection location, velocity, etc.) on the particle distribution and the tumor dose during transarterial injection of radioactive microspheres for treatment of hepatocellular carcinoma. However, these simulations are computationally costly, so we aim to evaluate whether these can be reliably simplified. MethodsWe identified and applied five simplification strategies (i.e. truncation, steady flow modelling, moderate and severe grid coarsening, and reducing the number of cardiac cycles) to a patient-specific CFD setup. Subsequently, we evaluated whether these strategies can be used to (1) accurately predict the CFD output (i.e. particle distribution and tumor dose) and (2) quantify the sensitivity of the model output to a specific injection parameter (injection flow rate). ResultsFor both accuracy and sensitivity purposes, moderate grid coarsening is the most reliable simplification strategy, allowing to predict the tumor dose with only a maximal deviation of 1.4 %, and a similar sensitivity (deviation of 0.7 %). The steady strategy performs the worst, with a maximal deviation in the tumor dose of 20 % and a difference in sensitivity of 10 %. ConclusionThe patient-specific 3D CFD simulations of this study can be reliably simplified by coarsening the grid, decreasing the computational time by roughly 45 %, which works especially well for sensitivity studies.

Hemodynamic effects of treatment with the ketone body 3-hydroxybutyrate in cardiogenic shock - a randomized, controlled, assessor-blinded porcine trial

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Novo Nordisk Foundation Independent Research Fund DK. Background Cardiogenic shock (CS) is a life-threatening disease with limited evidence-based treatment options. Treatment with the ketone body 3-hydroxybutyrate (3-OHB) induces favorable hemodynamic effects in patients with heart failure and CS. It increases cardiac output (CO) and left ventricular (LV) ejection fraction (LVEF) while reducing cardiac filling pressures. Yet, whether treatment with 3-OHB demonstrates beneficial hemodynamic effects during acute ischemic LV stunning in CS must be fully elucidated. This study aimed to examine the acute hemodynamic effects and underlying cardiovascular mechanisms of 3-OHB infusion in the acute phase of LV stunning in a porcine model of ischemic CS. Methods Sixteen 60-kg-pigs were included in a randomised, controlled, assessor-blinded crossover study. CS was achieved by repeated, slow injections of microspheres into the left main coronary artery. CS was defined as ≥30% reduction in CO and/or mixed venous saturation (SVO2). Upon the onset of CS, following a one-hour no-touch period, the pigs received an infusion with 3-OHB and isoosmolar, isovolumic saline (control) for two hours each in random order. Infusion periods were separated by a one-hour washout period. CO (primary endpoint), SVO2, and pulmonary pressures were measured by right heart catheterization. A pressure-volume admittance catheter was placed in the LV to measure LVEF, contractility (the slope of end systolic pressure-volume relationship, denoded as Ees), afterload (arterial elastance, Ea, and end-systolic pressure, ESP), preload (end-diastolic volume, EDV), and work-related parameters. Results CS was successfully achieved in all randomized animals. CO decreased by 36% from 4.5±1.0 L/min to 2.9±0.5 L/min (p&amp;lt;0.001) and SVO2 decreased by 31% from 55.0±8.1% to 37.7±5.8% (p&amp;lt;0.001). During 3-OHB infusion, CO increased by 0.9 L/min (95% CI: 0.4 to 1.3 L/min) compared with the control infusion. In parallel, Ees increased by 0.22 mmHg/mL (95% CI: 0.08 to 0.37 mmHg/mL), LVEF improved by 7 percentage points (95%CI: 1 to 13 percentage points) and cardiac efficiency increased by 6 percentage points (95%CI: 1 to 11 percentage points). Systemic vascular resistance was decreased by 479 dyn*cm5 (95% CI: 736 to 221 dyn*cm5); Ea and ESP remained similar. Heart rate was increased during 3-OHB infusion by 21 bpm (95% CI: 11 to 32 bpm) while no significant change was observed in stroke volume (p=0.6). Conclusion Treatment with 3-OHB improved CO, LVEF, and cardiac efficiency in CS. The increase was mediated through increased ventricular contractility and decreased peripheral resistance accompanied by increased heart rate.CO, Ees and cardiac efficiencyEndpoint parameters during 3-OHB

Mechanical Circulatory Support Reduces Directly Recorded Renal Sympathetic Nerve Activity in an Ovine Model of Cardiogenic Shock

Cardiogenic shock (CS) following myocardial infarction carries a high mortality risk despite advancements in management. The use of mechanical circulatory support in CS has become an effective strategy to improve haemodynamics and prevent acute kidney injury. However, the mechanism of how kidney function improves is unclear. We hypothesised that mechanical support would inhibit renal sympathetic nerve activity (RSNA), mediating renal protection in CS. Experiments were conducted in two groups of anaesthetised female sheep. In one group, CS was induced (n=8) using injections of polystyrene microspheres into the left coronary artery under fluoroscopic guidance. After a 30-minute baseline period (post -embolisation), intravenous phenylephrine infusion at incremental doses was used to assess the baroreflex control of RSNA before pump insertion. When the pressures recovered to baseline values, the circulatory assist Impella pump was inserted into the left ventricle and run randomly at different levels (P0 min-P6 max) with two minutes at each pump level. The controls underwent the same protocol without embolisation (n=6). Coronary artery embolisation resulted in a drop in mean arterial pressure (MAP) of 21 ± 4 mmHg compared to baseline values (n=8). This was associated with a 67% increase in renal sympathetic nerve activity (RSNA) from 16 ± 5 to 21 ± 5 spikes/s (p=0.038; n=7). Circulatory support using Impella significantly increased MAP from 55 ± 4 mmHg to 68 ± 5 mmHg at pump level P6 (one-way ANOVA, p&lt;0.001). Incremental pump support resulted in a significant decrease in RSNA (p&lt;0.001). At pump level P6, RSNA was decreased by 25 ± 5 % compared to P0 (p&lt;0.001). Baroreflex curves predicted a 2% reduction in RSNA at P6 equivalent pressures in CS, which was significantly less than that observed with circulatory support (p=0.006). In the control cohort with no CS, the changes in MAP and RSNA from P0 to P6 were qualitatively similar to the CS cohort. MAP increased from 84 ± 9 to 94 ± 8 mmHg (one-way ANOVA, p&lt;0.001) and RSNA decreased by 13 ± 5 % at P6 (one-way ANOVA, p&lt;0.001). The expected reduction in RSNA with baroreflex assessment at equivalent pressures to P6 was 5% in controls, which was not significantly different to what was observed (p=0.065). Our data indicate that the use of Impella pumps in CS reduces RSNA, which may mediate improvements in kidney function. Interestingly, the renal sympathoinhibition with the Impella pump is greater than that with vasoactive agents alone. We gratefully acknowledge the granting support from Abiomed and the University of Auckland Faculty Research Development Fund. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Infraorbital Injections of Polymethylmethacrylate Microspheres: Treatments for Delayed Granulomatous Inflammation.

Infraorbital Injections of Polymethylmethacrylate Microspheres: Treatments for Delayed Granulomatous Inflammation.

Long-Acting Strategies for Antibody Drugs: Structural Modification, Controlling Release, and Changing the Administration Route.

Because of their high specificity, high affinity, and targeting, antibody drugs have been widely used in the treatment of many diseases and have become the most favored new drugs for research in the world. However, some antibody drugs (such as small-molecule antibody fragments) have a short half-life and need to be administered frequently, and are often associated with injection-site reactions and local toxicities during use. Increasing attention has been paid to the development of antibody drugs that are long-acting and have fewer side effects. This paper reviews existing strategies to achieve long-acting antibody drugs, including modification of the drug structure, the application of drug delivery systems, and changing their administration route. Among these, microspheres have been studied extensively regarding their excellent tolerance at the injection site, controllable loading and release of drugs, and good material safety. Subcutaneous injection is favored by most patients because it can be quickly self-administered. Subcutaneous injection of microspheres is expected to become the focus of developing long-lasting antibody drug strategies in the near future.

Pulmonary CT perfusion robustly measures cardiac output in the context of multilevel pulmonary occlusion: a porcine study

BackgroundTo validate pulmonary computed tomography (CT) perfusion in a porcine model by invasive monitoring of cardiac output (CO) using thermodilution method.MethodsAnimals were studied at a single center, using a Swan-Ganz catheter for invasive CO monitoring as a reference. Fifteen pigs were included. Contrast-enhanced CT perfusion of the descending aorta and right and left pulmonary artery was performed. For variation purposes, a balloon catheter was inserted to block the contralateral pulmonary vascular bed; additionally, two increased CO settings were created by intravenous administration of catecholamines. Finally, stepwise capillary occlusion was performed by intrapulmonary arterial injection of 75-μm microspheres in four stages. A semiautomatic selection of AFs and a recirculation-aware tracer-kinetics model to extract the first-pass of AFs, estimating blood flow with the Stewart-Hamilton method, was implemented. Linear mixed models (LMM) were developed to calibrate blood flow calculations accounting with individual- and cohort-level effects.ResultsNine of 15 pigs had complete datasets. Strong correlations were observed between calibrated pulmonary (0.73, 95% confidence interval [CI] 0.6–0.82) and aortic blood flow measurements (0.82, 95% CI, 0.73–0.88) and the reference as well as agreements (± 2.24 L/min and ± 1.86 L/min, respectively) comparable to the state of the art, on a relatively wide range of right ventricle-CO measurements.ConclusionsCT perfusion validly measures CO using LMMs at both individual and cohort levels, as demonstrated by referencing the invasive CO.Relevance statementPossible clinical applications of CT perfusion for measuring CO could be in acute pulmonary thromboembolism or to assess right ventricular function to show impairment or mismatch to the left ventricle.Key points• CT perfusion measures flow in vessels.• CT perfusion measures cumulative cardiac output in the aorta and pulmonary vessels.• CT perfusion validly measures CO using LMMs at both individual and cohort levels, as demonstrated by using the invasive CO as a reference standard.Graphical

Pharmacokinetics and pharmacodynamics of perfluoropropane after intra-venous bolus injection of perflutren lipid microsphere injection (DEFINITY®) in healthy Chinese volunteers

Background and objectiveDefinity is an ultrasound contrast agent consisting of phospholipids-encapsulated perfluoropropane (PFP), also known as perflutren, microspheres, which is initially designed to enhance echocardiographic ultrasound images. With no pharmacologic action, Definity can increase the backscatter of ultrasound resulting enhanced ultrasound signals. The objective of this study was to determine the pharmacokinetics (PKs), Pharmacodynamics (PDs) and safety of Definity in healthy male and female Chinese volunteers.MethodsA simple GC-MS method was developed and applied to simultaneously quantify PFP both in human whole blood and in expired air using Perfluorobutane (PFB) as internal standard. Meanwhile, the blood microbubble Doppler intensities were continuously monitored as companion PDs by a Doppler ultrasonography system using a non-imaging method.ResultsAfter intravenous infusion of 10 µL/kg of PFP within 30 seconds, the mean AUClast of the pharmacokinetic analysis set was 0.000653 (uL/mL)*min, the average AUC∞ was 0.001051 (uL/mL)*min. The main coefficient of variation of parameters were within 30%. In this trial, the blood drug concentration of female subjects was lower than that of males. Female Cmax, AUClast and AUC∞ were lower than males’, Tmax and t1/2 was close to males’, Vss and CL were slightly higher than males’. The concentration of PFP in the expired air of the subject reached the maximum value 1–2 min after administration and the PFP accumulation curve in the expired air began to become flat at 9.5–11 min after administration. The PFP in the expired air at the last sampling point of most subjects was still measurable. The results of the analysis showed that female subjects had slightly more and faster PFP excretion via the lungs than males. The change of blood drug concentration in this trial was related to the change process of Doppler signal intensity. The trend of the two was close, but the peak time of blood drug concentration was slightly delayed compared with the peak time of the Doppler signal intensity. The results showed that female tmax−pd, t10 was earlier than male, and women have lower AUCpd than men.ConclusionThe pharmacokinetics and pharmacodynamics of Definity in blood and expired air were systematically evaluated for the first time in this study. The PK/PD analysis results of this trial showed that the change of blood concentration was related to the change process of Doppler signal intensity, the trend of the two was close and expired air are the main excretion pathways of Definity. Definity was well tolerated by all subjects in the trial.Trial registrationThis study was registered on 08 December 2017 at the Chinese Clinical Trial Registry (CTR20171087).

Analysis of vitreous by optical coherence tomography as biomarker in neurodegenerative diseases

Purpose: Neurodegeneration is multifactorial and the immune factor is key. Chronic and acute inflammation can be analysed as hyperreflective opacities in the vitreous (HOV) by optical coherence tomography (OCT) imaging. This study analyzes vitreous cellularity by OCT in two neurodegenerative diseases, chronic glaucoma (CG) and relapsing remitting multiple sclerosis (RRMS) compared to healthy individuals.Methods: Four models of CG generated in rats by episcleral veins sclerosis (EVS n = 35) or injection of biodegradable microspheres into the anterior chamber of the eye non‐loaded (Ms n = 28) and loaded with dexamethasone (Dex n = 43) and Dex‐fibronectin (DexFibro n = 44), compared to healthy rats (n = 32). In addition, patients with RRMS treated (n = 20) and healthy subjects (n = 20) were analysed. The relative intensity of vitreous/retinal pigment epithelium (VIT/RPE) obtained from OCT (for animal and human use) images was quantified. A custom program computational analysis characterizes in vivo the HOV (number and size), identified histologically as hyalocyte‐like Iba‐1+ (microglial marker) cells in animals. For humans, artificial intelligence methods and Image J software were used.Results: Both image analysis techniques identified HOV in animals with chronic glaucoma, in patients with RRMS and in healthy (both animals and humans). Chronic glaucoma models presented more HOV than healthy (decreasing from 100 ‐EVS‐ to 15 ‐healthy‐) (p &lt; 0.05). Corticosteroid models presented an anti‐inflammatory profile (with non‐activated cells as the highest population). However, according VIT/RPE intensity, patients with RRMS treated did not show differences vs. healthy humans (p &gt; 0.44).Conclusions: HOV analysed by OCT were identified in neurodegenerative diseases of chronic course, in outbreaks, and healthy individuals. The presence of anti‐inflammatory drugs (dexamethasone in animals) and immunemodulators (in humans) decreased the VIT/RPE intensity resembling healthy conditions.Acknowledgments: Grants MAT2017‐83858‐C2‐1 and MAT2017‐83858‐C2‐2 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”. Grants PID2020‐113281RB‐C21 and PID2020‐113281RB‐C22 funded by MCIN/AEI/ 10.13039/501100011033. Research Group UCM920415 (InnOftal). MJR thanks for the grants M17/00213 and JR22_00057.

Poly-l-lactic acid microspheres delay aging of epidermal stem cells in rat skin.

Injectable skin fillers offer a wider range of options for cutaneous anti-aging and facial rejuvenation. PLLA microspheres are increasingly favored as degradable and long-lasting fillers. The present study focused solely on the effect of PLLA on dermal collagen, without investigating its impact on the epidermis. In this study, we investigated the effects of PLLA microspheres on epidermal stem cells (EpiSCs). Different concentrations of PLLA microspheres on epidermal stem cells (EpiSCs) in vitro through culture, and identification of primary rat EpiSCs. CCK-8 detection, apoptosis staining, flow cytometry, Transwell assay, wound healing assay, q-PCR analysis, and immunofluorescence staining were used to detect the effects of PLLA on EpiSCs. Furthermore, we observed the effect on the epidermis by injecting PLLA into the dermis of the rat skin in vivo. PLLA microspheres promote cell proliferation and migration while delaying cell senescence and maintaining its stemness. In vitro, Intradermal injection of PLLA microspheres in the rat back skin resulted in delayed aging, as evidenced by histological and immunohistochemical staining of the skin at 2, 4, and 12 weeks of follow-up. This study showed the positive effects of PLLA on rat epidermis and EpiSCs, while providing novel insights into the anti-aging mechanism of PLLA.

Establishment of nonobstructive coronary microcirculatory disorders in rabbits using three established methods and a comparative study

To compare the merits and drawbacks of three approaches for establishing a rabbit model of nonobstructive coronary microcirculatory disease, namely, open thoracic subtotal ligation of coronary arteries, ultrasound-guided cardiac microsphere injection, and sodium laurate injection. New Zealand rabbits were allocated to four groups: a normal group (Blank group), an Open-chest group (Open-chest), a microsphere group (Echo-M), and a sodium laurate group (Echo-SL), each comprising 10 rabbits. The rabbits were sacrificed 24 h after the procedures, and their echocardiography, stress myocardial contrast echocardiography, pathology, and surgical times were compared. The results demonstrated varying degrees of reduced cardiac function in all three experimental groups, the Open-chest group exhibiting the most significant decline. The myocardial filling in the affected areas was visually analyzed by myocardial contrast echocardiography, revealing sparse filling at rest but more after stress. Quantitative analysis of perfusion parameters (β, A, MBF) in the affected myocardium showed reduced values, the Open-chest group having the most severe reductions. No differences were observed in stress myocardial acoustic imaging parameters between the Echo-M and Echo-SL groups. Among the pathological presentations, the Open-chest model predominantly exhibited localized ischemia, while the Echo-M model was characterized by mechanical physical embolism, and the Echo-SL model displayed in situ thrombosis as the primary pathological feature. Inflammatory responses and collagen deposition were observed in all groups, with the severity ranking of Open-chest > Echo-SL > Echo-M. The ultrasound-guided intracardiac injection method used in this experiment outperformed open-chest surgery in terms of procedural efficiency, invasiveness, and maneuverability. This study not only optimizes established cardiac injection techniques but also offers valuable evidence to support clinical investigations through a comparison of various modeling methods.