Citations

ABSTRACT The FDA Modernization Act 3.0 represents a pivotal shift in biomedical research by formally removing the requirement for animal testing and enabling regulatory acceptance of New Approach Methodologies (NAMs). This transition creates an urgent need for robust, human‐relevant biomarkers that can anchor NAM‐generated data within regulatory decision‐making, particularly for first‐in‐human studies. Extracellular vesicles (EVs), owing to their biological stability, accessibility and rich molecular cargo, may be well positioned to fulfil this role. EVs reflect dynamic cellular states and intercellular communication, making them mechanistically informative readouts of pharmacology, toxicity, immune modulation and disease biology across human‐derived model systems. This Perspective outlines how EV‐based biomarkers can support the qualification, standardization, and regulatory acceptance of NAMs, with particular emphasis on ex vivo platforms such as organoids, microtissue systems, organ‐on‐chip devices and perfused tissue slices. We highlight the advantages of EVs for longitudinal, non‐destructive sampling, representation of human variability, and integration with quantitative systems pharmacology and physiologically based pharmacokinetic models. Finally, we discuss the scientific, operational and regulatory challenges that must be addressed and argue that coordinated leadership from the International Society for Extracellular Vesicles (ISEV) is essential. The convergence of regulatory reform and EV science presents a timely call to action to establish EVs as foundational biomarkers in next‐generation, human‐centric drug development.

Abstract Multidrug efflux pumps transport antibiotics across the cellular membrane resulting in resistance conferred to the host organism. Efflux pump inhibitors (EPIs) potentiate the efficacy of antibiotics by blocking drug efflux and hold promise as adjuvant therapeutics in the fight against multidrug resistant pathogenic bacteria. A hurdle in the field has been the lack of selectivity of small molecule EPIs which often display off-target toxicity due to non-specific binding. To tackle this specificity challenge, we aimed to maximize an inhibitor’s binding surface area to efflux pumps by designing miniprotein EPIs using computational protein design and an E. coli co-expression assay to screen inhibition in cells. We used S. aureus NorA as a model efflux transporter since it confers drug resistance to fluoroquinolones, puromycin, and other cytotoxic compounds. Starting from a focused miniprotein library of only 86 members, we identified inhibitors in the screen that blocked NorA transport under active efflux conditions in vitro . Our most promising inhibitor I-23 was validated by solving a cryo-EM structure of the miniprotein in complex with NorA, which stabilized the transporter in the outward-open conformation. I-23 has a ferredoxin-like fold with one of its β-hairpins inserted into the substrate binding pocket of NorA and other parts of the globular fold occupying the shallow pocket and making extensive intermolecular contacts with NorA. An arginine residue on the tip of the hairpin loop was positioned near an anionic patch required for NorA antibiotic efflux. The identified structural motifs in this work could be employed to explore the molecular properties of peptidoglycan penetration; full realization of the therapeutic potential of the designed miniprotein inhibitors will require determining the principles for facilitating passage of ∼7 to 8 kDa miniproteins across the peptidoglycan bacterial cell wall.

Background Exercise cardiac catheterization is the gold standard for diagnosing diastolic dysfunction and impaired pulmonary reserve in patients with Fontan circulation. The diagnostic value of noninvasive parameters is unclear. Methods Patients who underwent simultaneous exercise hemodynamic evaluation and peripheral venous pressure (PVP) measurement were included. Echocardiographic surrogates for ventricular filling pressure were compared with invasive measures. Diastolic dysfunction was defined invasively as either resting pulmonary artery wedge pressure ≥12 mm Hg or exercise pulmonary artery wedge pressure >20 mm Hg. Results Twenty‐nine patients were included. Age at catheterization was 34±9 years. Atrioventricular valve systole‐to‐diastole duration ratio (S/D) and resting PVP were significant predictors of resting pulmonary artery wedge pressure (S/D: β=0.71 per 0.1 S/D [95% CI, 0.16–1.25]; P =0.01; PVP: β=0.68 per mm Hg [95% CI, 0.41–0.96]; P <0.001). By contrast, resting PVP was a predictor of diastolic dysfunction, whereas S/D was not. Based on these data, we proposed a 2‐tier assessment algorithm with the first tier considering resting PVP ≤15 mm Hg and S/D ≤1.1 and the second tier considering exercise PVP ≤25 mm Hg in those with 1 elevated resting parameter. This algorithm showed a positive predictive value of 88% (95% CI, 47%–100%), a negative predictive value of 90% (95% CI, 70%–99%), a sensitivity of 78% (95% CI, 40%–97%), and a specificity of 95% (95% CI, 75%–100%). Exercise PVP indexed to peak oxygen consumption also predicted invasively measured exercise pulmonary vascular resistance index (β=0.36 WU·m 2 per mm Hg/100 mL per min [95% CI, 0.08–0.64]; P =0.01). Conclusions This study presents a simple, noninvasive approach for evaluating diastolic function and pulmonary vascular reserve in patients with a Fontan circulation.

Abstract Prolonged infections in immunocompromised individuals may be a source for novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants, particularly when both the immune system and antiviral therapy fail to clear the infection and enable within-host evolution. Here we describe a 486-day case of SARS-CoV-2 infection in an immunocompromised individual. Following monotherapy with the monoclonal antibody Bamlanivimab, the individual’s virus acquired resistance, likely via the earliest known occurrence of Spike amino acid variant E484T. Recently, E484T has arisen again as a derivative of E484A in the Omicron Variant of Concern, supporting the hypothesis that prolonged infections can give rise to novel variants long before they become prevalent in the human population.

AbstractThe Society for Cardiovascular Angiography and Interventions (SCAI) Think Tank is a collaborative venture that brings together interventional cardiologists, administrative partners, and select members of the cardiovascular industry community annually for high‐level field‐wide discussions. The 2021 Think Tank was organized into four parallel sessions reflective of the field of interventional cardiology: (a) coronary intervention, (b) endovascular medicine, (c) structural heart disease, and (d) congenital heart disease. Each session was moderated by a senior content expert and co‐moderated by a member of SCAI's Emerging Leader Mentorship program. This document presents the proceedings to the wider cardiovascular community in order to enhance participation in this discussion, create additional dialog from a broader base, and thereby aid SCAI, the industry community and external stakeholders in developing specific action items to move these areas forward.

Abstract Higher bone marrow cell dose has been associated with improved survival after allogeneic BMT. Although PBSC provides higher cell dose, it also provides a higher number of T cells which increases the risk of GVHD and may negatively impact the outcome in pediatric patients. A prospective multi-center trial was conducted to evaluate the safety and feasibility of G-CSF primed bone marrow in children receiving HLA-identical sibling bone marrow transplantation (BMT). Thirty eight children at 9 different centers, 17 female and 21 male with a median age of 9.8 years (range 0.8–17) were enrolled between May 2003 and May 2005. Fifteen patients had high risk diseases (ALL ≥CR2=4, AML≥ CR2/refractory=5, Advanced MDS=3, JMML=1, NHL=2) and 23 had standard risk disease (SAA=6, Red Cell Aplasia=1, Sickle cell disease=1, CML-CP=2, AML CR1=9, ALL CR1=2, MDS-RA=2). Five patients had undergone a prior allogeneic transplant. All patients received myeloablative preparative regimens (Cy/TBI±VP-16=12, BU/Cy±other=20 and Cy/ATG=6) and 32 (84%) received CSP/FK506 with MTX as GVHD prophylaxis. Donors were HLA identical siblings except for one who was syngeneic. Donors with median age of 9.2 y (range 1.1–22) received 5 mcg/kg/day of GCSF SQ for 5 consecutive days. Bone marrow was collected on the fifth day with a median volume of 14.5 cc/kg (range 5.2–25). No donor experienced any complications related to G-CSF administration or harvest, up to the time of last follow-up at one month after the harvest. The absolute CD34 cell count at the day of the harvest was measured in 28 patients and it was significantly higher in bone marrow compared to peripheral blood, median of 50/μl (8–247) vs 513/μl (116–156) respectively (p <0.0001). Median nucleated and CD 34 cells infused was 8.4x108/kg (range 2.4–60.9) and 8.7x106/kg (range 2–27.6) respectively. No G-CSF was administered post transplant. All patients had neutrophil engraftment at a median of 19 days (13–28), and all but one patient with early post-transplant relapse had platelet engraftment at a median of 20 days (9–44). Thirteen patients (35%) developed grade 2 GVHD and 4 of 34 evaluable patients (12%) developed chronic GVHD (3 limited and 1 extensive). There was no transplant related mortality. Among 30 patients with malignant disorders 9 (30%) relapsed (6 with high risk and 3 with standard risk disease). The EFS and OS of patients with standard disease at 1 year is 84% (95% CI 68–100%) and 95% (95% CI 87–100) respectively. With a median follow up of 1 year the estimated EFS and OS of all patients at one year is 76% (CI 62–93) and 92% (95% CI 83–100) respectively. We conclude that G-CSF primed bone marrow from pediatric donors is safe and can result in high NC and CD34 cell dose that facilitate engraftment after myeloablative BMT without a discernable increase in the risk of GVHD. A prospective randomized trial comparing G-CSF primed bone marrow to unstimulated marrow is planned.

ABSTRACT The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell‐released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV‐associated functional activities. Finally, a checklist is provided with summaries of key points.