Biodistribution of mesenchymal stromal cell-derived extracellular vesicles administered during acute lung injury.

BACKGROUND: Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) are a promising cell-free therapy for acute lung injury (ALI). To date, no studies have investigated their biodistribution in ALI or discerned the timing of administration for maximal lung targeting, which are crucial considerations for clinical translation. Our study aimed to characterize a mouse model of ALI and establish the distribution kinetics and optimal timing of MSC-EV delivery during lung injury. METHODS: MSC-EVs were isolated by ultracentrifugation alone (U/C) or tangential flow filtration with ultracentrifugation (TFF-U/C) and characterized by nanoparticle tracking analysis and western blot. A lipopolysaccharide (LPS)-induced mouse model of ALI was established to study the inflammatory response over 72 h. ALI was assessed by histological lung injury score, bronchoalveolar lavage fluid cell count and inflammatory cytokines. For biodistribution studies, ALI mice were intravenously administered fluorescently labeled MSC-EVs to determine the optimal timing of administration and organ-specific biodistribution. Live in vivo and ex vivo fluorescence imaging was conducted at various timepoints post-EV injection. RESULTS: EVs isolated by either ultracentrifugation alone or TFF-U/C displayed comparable size distribution (~ 50-350 nm) and EV marker expression (CD63/81). TFF-U/C generated a 5.4-fold higher particle concentration and 3.9-fold higher total protein when compared to ultracentrifugation alone. From the inflammatory time-course study, cell count and IL-1ß peaked in bronchoalveolar lavage fluid at 24 h after ALI induction. MSC-EVs delivered at 24 h (as opposed to 0.5 h, 5 h or 10 h) after disease induction resulted in a 2.7-4.4-fold higher lung uptake of EVs. Biodistribution studies comparing organ-specific MSC-EV uptake showed progressive lung accumulation up to 48 h post-delivery (threefold higher than the spleen/liver), with a decline at 72 h. Importantly, lung EV fluorescence at 48 h in ALI mice was significantly elevated as compared to control mice. The lung tropism of MSC-EVs was further validated as therapeutically inert EVs derived from HEK293T cells accumulated mainly to the spleen and liver with a 5.5-fold lower distribution to the lungs as compared to MSC-EVs. CONCLUSION: MSC-EVs exhibit maximal lung accumulation when administered during heightened inflammation at 24 h after ALI induction. This lung tropism suggests that MSC-EVs may serve as a practical rescue treatment for acute inflammatory respiratory conditions.

MSC-Derived Extracellular Vesicles to Heal Diabetic Wounds: a Systematic Review and Meta-Analysis of Preclinical Animal Studies.

INTRODUCTION: Extracellular vesicles from mesenchymal stromal cells (MSC-EVs) have shown promise in wound healing. Their use in diabetic wounds specifically, however, remains pre-clinical and their efficacy remains uncertain less clear. A systematic review of preclinical studies is needed to determine the efficacy of MSC-EVs in the treatment of diabetic wounds to accelerate the clinical translation of this cell-based therapy. METHODS: PubMed and Embase were searched (to June 23, 2020). All English-language, full-text, controlled interventional studies comparing MSC-EVs to placebo or a "no treatment" arm in animal models of diabetic wounds were included. Study outcomes, including wound closure (primary outcome), scar width, blood vessel number and density, and re-epithelialisation were pooled using a random effects meta-analysis. Risk of bias (ROB) was assessed using the SYRCLE tool for pre-clinical animal studies. RESULTS: A total of 313 unique records were identified from our search, with 10 full text articles satisfying inclusion criteria (n = 136 animals). The administration of MSC-EVs improved closure of diabetic wounds compared to controls with a large observed effect (Standardized Mean Difference (SMD) 5.48, 95% Confidence Interval (CI) 3.55-8.13). Healing was further enhanced using MSC-EVs enriched in non-coding RNAs or microRNAs compared to controls (SMD 9.89, 95%CI 7.32-12.46). Other outcomes, such as blood vessel density and number, scar width, and re-epithelialisation were improved with the administration of MSC-EVs, with a large effect. ROB across studies was unclear. CONCLUSION: MSC-EVs, particularly following enrichment for specific RNAs, are a promising treatment for diabetic wounds in pre-clinical studies and translation to the clinical domain appears warranted. REGISTRATION: PROSPERO #CRD42020199327 [248]. Forest plot demonstrating increased wound closure rates of diabetic wounds receiving genetically modified MSC-EVs that were enriched for specific RNAs. DFO = deferoxamine. Control groups were inactive (no treatment or saline) except for 3 studies which used hydrogels without MSC-EVs as control (Li M 2016; Shi 2017; Tao 2016).

Mesenchymal Stromal Cell-derived Extracellular Vesicles in Preclinical Animal Models of Tumor Growth: Systematic Review and Meta-analysis.

BACKGROUND: Mesenchymal stromal cell derived extracellular vesicles (MSC-EVs) have been implicated in the regulation of tumor growth. Studies remain preclinical with effects ranging from inhibition of tumor growth to cancer progression. A systematic review and meta-analysis is needed to clarify the effect of MSC-EVs on tumor growth to facilitate potential translation to clinical trials. METHODS: A systematic search of the literature (MEDLINE, Embase, and BIOSIS databases to June 1, 2019) identified all pre-clinical controlled studies investigating the effect of MSC-EVs on tumor growth. Study selection and data extraction were performed in duplicate. Potential risk of bias was assessed using the SYRCLE tool. A random effects meta-analysis of reduction in tumor weight/volume (primary outcome) was performed. RESULTS: We identified 29 articles and 22 reported data on tumor responses that were included for meta-analysis. Studies were associated with unclear risk of bias in a large proportion of domains in accordance with the SYRCLE tool for determining risk of bias in preclinical studies. A high risk of bias was not identified in any study. MSC-EVs had a mixed response on tumor progression with some studies reporting inhibition of tumor growth and others reporting tumor progression. Overall, MSC-EVs exerted a non-significant reduction in tumor growth compared to controls (standardized mean difference (SMD) -0.80, 95 % CI -1.64 to 0.03, p = 0.06, I2 = 87 %). Some studies reported increased tumor growth which aligned with their stated hypothesis and some interrogated mechanisms in cancer biology. EVs isolated from MSCs that overexpressed anti-tumor RNAs were associated with significant tumor reduction in meta-analysis (SMD - 2.40, 95 % CI -3.36 to -1.44, p < 0.001). Heterogeneity between studies was observed and included aspects of study design such as enrichment of MSC-EVs with specific anti-tumor molecules, tissue source of MSCs, method of EV isolation, characterization of MSCs and EVs, dosage and administration schedules, and tissue type and source of tumor cells studied. CONCLUSIONS: MSC-EVs are associated with mixed effects on tumor growth in animal models of cancer. In studies where anti-tumor RNAs are packaged in EVs, a significant reduction in tumor growth was observed. Reducing heterogeneity in study design may accelerate our understanding of the potential effects of MSC-EVs on cancer. [274 words] Forest plot of MSC-EV effect on tumor growth accordinggenetic modification of EVs in animal studies identified from a systematicreview of the literature. All cohorts from studies with multiple interventiongroups are presented separately with control groups divided equally among thegroups. M, modified; H, hypoxia.

MSC-Derived Extracellular Vesicles in Preclinical Animal Models of Bone Injury: A Systematic Review and Meta-Analysis.

BACKGROUND AND OBJECTIVE: Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) are a promising treatment for bone injuries, although studies remain preclinical. A systematic review and meta-analysis can assess the efficacy of MSC-EVs and identify treatment aspects associated with enhanced bone repair. METHODS: English language, preclinical, controlled, in vivo studies identified in our systematic search (up to May 8, 2020) examining the use of MSC-EVs in bone healing were included. Risk of bias (ROB) was assessed using the SYRCLE tool. Aggregate Data Meta-Analysis was performed to determine the effect of MSC-EVs on Bone Volume/Total Volume (BV/TV) and New Bone Formation (NBF). RESULTS: Thirteen studies were included. Twelve reported either BV/TV or NBF and were included in meta-analysis. ROB was unclear in all studies. Overall, MSC-EVs displayed benefit in terms of bone healing for both BV/TV (22.2% mean difference (MD); 95% CI: 15.8-28.5%, p < 0.001) and NBF (26.1% MD; 10.3-41.8%, p = 0.001) versus controls. Substantial heterogeneity, however, was observed between studies. MSC-EVs were reported to activate multiple signaling pathways including mTOR/AKT, AMPK and BMP2. Subgroup analysis indicated no significant difference in the improvement of BV/TV when using modified EVs isolated after gene transfection, preconditioning (p = 0.61), or using EVs in combination with a tissue scaffold and/or hydrogel versus other delivery methods (p = 0.20). CONCLUSION: Use of MSC-EVs to promote healing of bone injury appears promising, however, heterogeneity between studies and the potential for reporting bias limits confidence in the extent of benefit. Reducing bias between studies and addressing aspects of potential reporting bias should augment confidence in future meta-analyses and propel the field towards clinical studies. Forest Plot analysis assessing the percentage change in bone volume (BV) / total volume (TV) in the presence (experimental) or absence (control) of MSC-EVs.

Mesenchymal stromal cell extracellular vesicles as therapy for acute and chronic respiratory diseases: A meta-analysis.

Preclinical studies suggest mesenchymal stromal cell extracellular vesicles (MSC-EVs) reduce inflammation and improve organ function in lung diseases; however, an objective analysis of all available data is needed prior to translation. Using rigorous meta-research methods, we determined the effectiveness of MSC-EVs for preclinical respiratory diseases and identified experimental conditions that may further refine this therapy. A systematic search of MEDLINE/Embase identified 1167 records. After screening, 52 articles were included for data extraction and evaluated for risk of bias and quality of reporting in study design. A random effects meta-analysis was conducted for acute lung injury (ALI; N = 23), bronchopulmonary dysplasia (BPD; N = 8) and pulmonary arterial hypertension (PAH; N = 7). Subgroup analyses identified EV methods/characteristics that may be associated with improved efficacy. Data is presented as standardized mean differences (SMD) or risk ratios (RR) with 95% confidence intervals (CI). For ALI, MSC-EVs markedly reduced lung injury (SMD -4.33, CI -5.73 to -2.92), vascular permeability (SMD -2.43, CI -3.05 to -1.82), and mortality (RR 0.39, CI 0.22 to 0.68). Small EVs were more consistently effective than large EVs whereas no differences were observed between tissue sources, immunocompatibility or isolation techniques. For BPD, alveolarization was improved by MSC-EVs (SMD -1.45, CI -2.08 to -0.82) with small EVs more consistently beneficial then small/large EVs. In PAH, right ventricular systolic pressure (SMD -4.16, CI -5.68 to -2.64) and hypertrophy (SMD -2.80, CI -3.68 to -1.91) were significantly attenuated by EVs. In BPD and PAH, EVs isolated by ultracentrifugation demonstrated therapeutic benefit whereas tangential flow filtration (N = 2) displayed minimal efficacy. Lastly, risk of bias and quality of reporting for experimental design were consistently unclear across all studies. Our findings demonstrate clear potential of MSC-EVs to be developed as therapy for acute and chronic lung diseases. However, greater transparency in research design and direct comparisons of isolation technique and EV subtypes are needed to generate robust evidence to guide clinical translation. Protocol Registration: PROSPERO CRD42020145334.

Preclinical Studies of MSC-Derived Extracellular Vesicles to Treat or Prevent Graft Versus Host Disease: a Systematic Review of the Literature.

INTRODUCTION: Treating and preventing graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplant (HCT) remains a significant challenge. The use of mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) appears promising and a systematic review of preclinical studies is needed to accelerate the design of translational studies. METHODS: We identified 4 eligible studies from a systematic review performed on December 1, 2018. In brief, eligible studies included the treatment or prevention of GVHD in animal models and the use of MSC-EVs. Study design and outcome data were extracted and reporting was evaluated using the SYRCLE tool to identify potential bias. RESULTS: Two studies assessed the efficacy of MSC-EVs in treatment of GVHD and 2 studies address prevention. Mice treated with MSC-EVs showed improved median survival, GVHD clinical scores and histology scores as compared to untreated mice with GVHD. Prophylactic treatment with MSC-EVs attenuated GVHD severity and improved median survival as compared to no treatment or saline. CONCLUSION: Our systematic review provides important insight regarding the potential of MSC-EVs to treat or prevent GVHD. Although few studies were identified, improved survival and attenuated histologic findings of GVHD were observed in mice after MSC-EV administration for the treatment and prevention of GVHD. Dosing of EVs and route of administration remain inconsistent, however, and scalability of EV isolation for clinical studies remains a challenge. Standardized outcome reporting is needed to pool results for metanalysis. Graphical abstract.

Identifying and understanding factors that affect the translation of therapies from the laboratory to patients: a study protocol.

Background: The process of translating preclinical findings into a clinical setting takes decades. Previous studies have suggested that only 5-10% of the most promising preclinical studies are successfully translated into viable clinical applications. The underlying determinants of this low success rate (e.g. poor experimental design, suboptimal animal models, poor reporting) have not been examined in an empirical manner. Our study aims to determine the contemporary success rate of preclinical-to-clinical translation, and subsequently determine if an association between preclinical study design and translational success/failure exists. Methods: Established systematic review methodology will be used with regards to the literature search, article screening and study selection process. Preclinical, basic science studies published in high impact basic science journals between 1995 and 2015 will be included. Included studies will focus on publicly available interventions with potential clinical promise. The primary outcome will be successful clinical translation of promising therapies - defined as the conduct of at least one Phase II trial (or greater) with a positive finding. A case-control study will then be performed to evaluate the association between elements of preclinical study design and reporting and the likelihood of successful translation. Discussion: This study will provide a comprehensive analysis of the therapeutic translation from the laboratory bench to the bedside. Importantly, any association between factors of study design and the success of translation will be identified. These findings may inform future research teams attempting preclinical-to-clinical translation. Results will be disseminated to identified knowledge users that fund/support preclinical research.

An Analysis of Mesenchymal Stem Cell-Derived Extracellular Vesicles for Preclinical Use.

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) can reduce inflammation, promote healing, and improve organ function, thereby providing a potential "cell-free" therapy. Prior to clinical translation, it is critical to synthesize existing evidence on preclinical methods and efficacy. To address these issues, we used gold standard systematic review methodology to consolidate information from all published animal studies investigating MSC-EVs as an intervention. A systematic search of MEDLINE and Embase identified 206 studies. Data were extracted in duplicate for methodology, experimental design, interventional traits, modifications, and outcomes. MSC-EVs were used to treat a variety of diseases and demonstrated benefits in 97% of studies. Adverse effects were reported in only three studies, two demonstrating tumor growth. A quarter of articles modified EVs to enhance efficacy, with 72% leading to markedly improved outcomes as compared to unmodified EVs. However, several key methodological concerns were evident. Only 60% of studies used nomenclature consistent with the size definitions of EVs. Ultracentrifugation (70%) and isolation kits (23%) were the most common isolation techniques with noted differences in yield and purity. EVs were inconsistently dosed by protein (68%) or particle concentration (16%). Two-thirds of studies administered xenogeneic EVs, suggesting immunocompatibility. Less than 25% of studies assessed EV biodistribution. Approaches for determining size, protein markers, and morphology were highly heterogeneous, with only 12 and 4 studies meeting the MISEV 2014 and 2018 recommendations, respectively. Knowledge gaps identified from this systematic review highlight important opportunities to improve preclinical design and methodology in the rapidly growing field of EV therapeutics.

Mesenchymal stromal cell-derived extracellular vesicles for regenerative therapy and immune modulation: Progress and challenges toward clinical application.

Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) have emerged as a promising form of regenerative therapy and immune modulation. Fundamental advances in our understanding of MSCs and EVs have allowed these fields to merge and create potential cell-free therapy options that are cell-based. EVs contain active cargo including proteins, microRNA, and mRNA species that can impact signaling responses in target cells to modify inflammatory and repair responses. Increasing numbers of preclinical studies in animals with various types of injury models have been published that demonstrate the potential impact of MSC-EV therapy. Although the emergence of registered clinical protocols suggests translation to clinical application has already begun, several barriers to more widespread clinical adoption remain. In this review, we highlight the progress made in MSC-derived small EV-based therapy by summarizing aspects pertaining to the starting material for MSC expansion, EV production, and isolation methods, studies from preclinical models that have established a foundation of knowledge to support translation into the patient setting, and potential barriers to overcome on the path to clinical application.

Endogenous Glucocorticoid Response to Single-Dose Dexamethasone for Croup in Children: A Pharmacodynamic Study.

OBJECTIVES: Dexamethasone is associated with adrenal insufficiency in adults and children with chronic disease. This association has not been studied after single-dose oral dexamethasone, the standard of care for children with croup. We hypothesized that single-dose oral dexamethasone in children with croup is associated with a transient decrease in endogenous glucocorticoids. METHODS: We conducted a prospective, 2-arm, pharmacodynamic study of single-dose oral dexamethasone 0.6 mg/kg (maximum, 12 mg) in children older than 2 years with croup compared with controls (children with febrile upper respiratory tract infections who did not receive dexamethasone). Primary outcome was urinary 6ß-hydroxycortisol-cortisol ratio. RESULTS: Twenty-seven children were analyzed (22 with croup and 5 with upper respiratory tract infections). Median 6ß-hydroxycortisol-cortisol ratios before dexamethasone, the following morning, and on days 1, 3, and 7 were 2.8, 2.2, 2.0, 2.8, and 2.6, respectively. Among controls, the median 6ß-hydroxycortisol-cortisol ratios at the same time intervals was 1.9, 1.5, 1.8, 2.5, and 1.7, respectively. There were no significant differences in the change from time 0 between groups at any time point. There were no serious adverse events or infectious complications. CONCLUSIONS: Single-dose oral dexamethasone is not associated with decreased endogenous corticosteroid levels in children with croup. Future studies should use criterion standard tests to rule out suppression of the hypothalamic-pituitary-adrenal axis and be powered sufficiently to identify adverse clinical outcomes.

Methods and efficacy of extracellular vesicles derived from mesenchymal stromal cells in animal models of disease: a preclinical systematic review protocol.

BACKGROUND: Over the past decade, mesenchymal stromal cells have been increasingly investigated for their therapeutic potential in several different illnesses. However, cell therapy can be limited by potentially serious adverse events including cell embolus formation and tumorigenesis. Importantly, the protective effects of mesenchymal stromal cells are largely mediated by paracrine mechanisms including release of extracellular vesicles. This systematic review intends to synthesize the current knowledge of mesenchymal stromal cell-derived extracellular vesicles as a therapeutic option for preclinical models of disease, inflammation, or injury. METHODS: A systematic literature search of MEDLINE, Embase, and BIOSIS databases will be conducted. Interventional preclinical in vivo studies using extracellular vesicles derived from any tissue source of mesenchymal stromal cells will be included. Studies will be screened by abstract, and full-text by two independent reviewers. Eligible studies will undergo data extraction with subcategorization into domains based on disease. Methods utilized for extracellular vesicle characterization and isolation will be collected, as well as information on interventional traits, such as tissue source of mesenchymal stromal cells, dosage regimen, and vesicle modifications. Reported outcomes will be collected to determine which diseases studied may be impacted most from treatment with mesenchymal stromal cell-derived extracellular vesicles. DISCUSSION: This systematic review will summarize preclinical studies investigating the therapeutic efficacy of both small and large extracellular vesicles derived by mesenchymal stromal cells. Extracellular vesicles represent a possibility to harness the benefits of mesenchymal stromal cells with added benefits of reduced manufacturing costs and an improved safety profile. Hence, there has been an exponential increase in interest for developing this cell-free therapy with hundreds of preclinical studies published to date. However, a vast amount of heterogeneity between groups relates to methods of extracellular vesicle isolation, characterization, and study design. This review will capture this heterogeneity and identify the most commonly used and optimal approaches to evaluate mesenchymal stromal cell-derived extracellular vesicle treatment. A meta-analysis of outcomes within each disease domain will help elucidate which fields of research demonstrate promise for developing extracellular vesicles as a novel cell-free therapy. Summarizing this robust information on extracellular vesicles as an intervention can provide guidance for designing preclinical studies with hopes of future clinical translation.

The effect of chronic kidney disease on CYP2B expression and activity in male Wistar rats.

Chronic kidney disease (CKD) is characterized by progressive reduction in kidney function over time. CKD affects greater than 10% of the population and its incidence is on the rise due to the growing prevalence of its risk factors. Previous studies demonstrated CKD alters nonrenal clearance of drugs in addition to reducing renal clearance. We assessed the function and expression of hepatic CYP2B enzymes using a rat model of CKD. CKD was induced in Wistar rats by supplementing their chow with adenine and confirmed through the detection of elevated uremic toxins in plasma. Liver enzymes AST and ALT were unchanged by the adenine diet. Bupropion was used as a probe substrate for hepatic CYP2B function using rat liver microsomes. The resulting metabolite, hydroxy-bupropion, and bupropion were quantified by ultra-performance liquid chromatography coupled to time-of-flight mass spectrometry. Level of mRNA and protein were determined by RT-PCR and Western blot, respectively. The results of our study demonstrate that CYP2B1 is downregulated in a rat model of CKD. CYP2B1 mRNA level was significantly decreased (88%, P < 0.001) in CKD relative to control. Similarly, maximal enzymatic velocity (Vmax) for CYP2B was decreased by 46% in CKD relative to control (P < 0.0001). Previous studies involving patients with CKD demonstrated altered bupropion pharmacokinetics compared to control. Hence, our results suggest that these alterations may be mediated by attenuated CYP2B hepatic metabolism. This finding may partially explain the alterations in pharmacokinetics and nonrenal drug clearance frequently observed in patients with CKD.

ß-Blocker Dialyzability in Maintenance Hemodialysis Patients: A Randomized Clinical Trial.

BACKGROUND AND OBJECTIVES: There is a paucity of data available to describe drug dialyzability. Of the available information, most was obtained before implementation of modern hemodialysis membranes. Our study characterized dialyzability of the most commonly prescribed ß-blockers in patients undergoing high-flux hemodialysis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Patients on hemodialysis (n=8) were recruited to an open label, pharmacokinetic, four-way crossover trial. Single doses of atenolol, metoprolol, bisoprolol, and carvedilol were administered on separate days in random order to each patient. Plasma and dialysate drug concentrations were measured, and dialyzability was determined by the recovery clearance and arterial venous difference methods. RESULTS: Using the recovery clearance method, the dialytic clearance values for atenolol, metoprolol, bisoprolol, and carvedilol were 72, 87, 44, and 0.2 ml/min, respectively (P<0.001). Applying the arterial venous difference method, the dialytic clearance values of atenolol, metoprolol, bisoprolol, and carvedilol were 167, 114, 96, and 24 ml/min, respectively (P<0.001). CONCLUSIONS: Atenolol and metoprolol are extensively cleared by hemodialysis compared with the negligible dialytic clearance of carvedilol. Contrary to estimates of dialyzability on the basis of previous literature, our data indicate that bisoprolol is also dialyzable. This finding highlights the importance of conducting dialyzability studies to definitively characterize drug dialytic clearance.

Coffee inhibition of CYP3A4 in vitro was not translated to a grapefruit-like pharmacokinetic interaction clinically.

Grapefruit can augment oral medication bioavailability through irreversible (mechanism-based) inhibition of intestinal CYP3A4. Supplementary data from our recent coffee-drug interaction clinical study showed some subjects had higher area under the plasma drug concentration - time curve (AUC) and plasma peak drug concentration (Cmax) of the CYP3A4 probe felodipine compared to aqueous control. It was hypothesized that coffee might interact like grapefruit in responsive individuals. Beans from six geographical locations were consistently brewed into coffee that was separated chromatographically to a methanolic fraction for in vitro inhibition testing of CYP3A4 metabolism of felodipine at 1% coffee strength. The effect of simultaneous incubation and 10-min preincubation with coffee fractions determined whether coffee had direct and mechanism-based inhibitory activity. A subsequent five-way randomized balanced controlled crossover clinical study evaluated the clinical pharmacokinetic interaction with single-dose felodipine. Grapefruit juice, water, or three of the in vitro tested coffees were ingested at 300 mL alone 1 h before and then with felodipine. In vitro, all six coffees decreased felodipine metabolism for both simultaneous and preincubation exposure compared to corresponding control. Five coffees demonstrated mechanism-based inhibition. Grapefruit increased felodipine AUC0-8 (25 vs. 13 ng.h/mL, P < 0.001) and Cmax (5.8 vs. 2.7 ng/mL, P < 0.001) and decreased dehydrofelodipine/felodipine AUC0-8 ratio (0.84 vs. 1.29, P < 0.001), while the three coffees caused no change in these parameters compared to water. Despite high in vitro potency of CYP3A4 inhibition, the coffees did not cause a clinical pharmacokinetic interaction possibly from insufficient amount of inhibitor(s) in coffee reaching intestinal CYP3A4 during the absorption phase of felodipine. The results of this study highlight the need for follow-up clinical testing when in vitro results indicate the possibility of an interaction.

Untargeted plasma and tissue metabolomics in rats with chronic kidney disease given AST-120.

Chronic kidney disease (CKD) results in the accumulation of metabolic waste products that are normally cleared by the kidney, known as uremia. Many of these waste products are from bacteria metabolites in the gut. Accumulation of uremic toxins in plasma and tissue, as well as the gut-plasma-tissue metabolic axis are important for understanding pathophysiological mechanisms of comorbidities in CKD. In this study, an untargeted metabolomics approach was used to determine uremic toxin accumulation in plasma, liver, heart and kidney tissue in rats with adenine-induced CKD. Rats with CKD were also given AST-120, a spherical carbon adsorbent, to assess metabolic changes in plasma and tissues with the removal of gut-derived uremic toxins. AST-120 decreased >55% of metabolites that were increased in plasma, liver and heart tissue of rats with CKD. CKD was primarily defined by 8 gut-derived uremic toxins, which were significantly increased in plasma and all tissues. These metabolites were derived from aromatic amino acids and soy protein including: indoxyl sulfate, p-cresyl sulfate, hippuric acid, phenyl sulfate, pyrocatechol sulfate, 4-ethylphenyl sulfate, p-cresol glucuronide and equol 7-glucuronide. Our results highlight the importance of diet and gut-derived metabolites in the accumulation of uremic toxins and define the gut-plasma-tissue metabolic axis in CKD.

Clearance of cardiovascular medications during hemodialysis.

PURPOSE OF REVIEW: To review the current understanding of hemodialysis-mediated clearance of commonly used cardiovascular medications. RECENT FINDINGS: Although cardiovascular drug dialyzability is poorly understood, many drug classes appear to include agents with substantially different degrees of dialyzability. Recent data suggest that more readily dialyzable beta-blockers associate with higher short-term mortality in patients initiating these drugs when on hemodialysis. Although this relationship was not observed in a later study with angiotensin-converting enzyme inhibitors of varying dialyzability, studies of this kind are currently limited by pharmacokinetic data that are either incomplete or no longer applicable to modern hemodialysis procedures. SUMMARY: There are substantial deficits in our understanding of cardiovascular medication dialyzability, which relates in large part to advances in the process of hemodialysis that have rendered older studies of dialyzability irrelevant. The importance of cardiovascular disease in patients receiving hemodialysis demands a better understanding of the effect hemodialysis exerts on cardiovascular drug pharmacokinetics.

Drug Disposition Issues in CKD: Implications for Drug Discovery and Regulatory Approval.

Patients with chronic kidney disease (CKD) have several comorbidities that require pharmacologic intervention including hypertension, diabetes, anemia, and cardiovascular disease. Advanced CKD patients (eg, treated with hemodialysis) take an average of 12 medications concurrently and are known to suffer from an increased number of medication-related adverse drug events. Recent basic and clinical research has identified altered renal and nonrenal drug clearance in CKD as one mediator of the increased adverse drug events observed in this patient population. This review will briefly describe pharmacokinetic considerations in CKD, review the Food and Drug Administration guidelines for performing pharmacokinetic studies in CKD patients, and outline the roles of academia, industry, and regulatory agencies in improving drug safety in CKD patients.