Actin filaments regulate microtubule growth at the centrosome.

The centrosome is the main microtubule-organizing centre. It also organizes a local network of actin filaments. However, the precise function of the actin network at the centrosome is not well understood. Here, we show that increasing densities of actin filaments at the centrosome of lymphocytes are correlated with reduced amounts of microtubules. Furthermore, lymphocyte activation resulted in disassembly of centrosomal actin and an increase in microtubule number. To further investigate the direct crosstalk between actin and microtubules at the centrosome, we performed in vitro reconstitution assays based on (i) purified centrosomes and (ii) on the co-micropatterning of microtubule seeds and actin filaments. These two assays demonstrated that actin filaments constitute a physical barrier blocking elongation of nascent microtubules. Finally, we showed that cell adhesion and cell spreading lead to lower densities of centrosomal actin, thus resulting in higher microtubule growth. We therefore propose a novel mechanism, by which the number of centrosomal microtubules is regulated by cell adhesion and actin-network architecture.

Hospital-based health technology assessment of innovative medical devices: insights from a nationwide survey in France.

OBJECTIVES: To better understand the process of hospital acquisition of innovative medical devices (MDs) and the hospital-based health technology assessment (HB-HTA) pathways in France, an in-depth study based on a quantitative approach is needed. The aim of the present study was to assess through a national survey how HB-HTA is currently implemented in French hospitals and to identify its level of formalization. METHODS: A quantitative online survey was conducted among hospitals performing HB-HTA in France, with a focus on the acquisition of innovative MDs for individual use. The survey, conducted between March and June 2022, was developed by a scientific board composed of members of the French-speaking Society for HB-HTA. RESULTS: Sixty-seven out of 131 surveyed hospitals with HB-HTA activities responded, including 29 university hospitals, 24 nonprofit private hospitals, and 14 local hospitals. Sixty-one respondents (91 percent) reported the existence of a process dedicated to evaluating innovative MDs; of these, 16 declared that their hospitals had a formalized unit with HB-HTA activity. These units were more frequently found in larger hospitals with more than 500 inpatient beds (n = 16, p = 0.0160) and in university hospitals (n = 12, p = 0.0158). No hospital reported any collaboration with HAS, the French national HTA agency. CONCLUSION: A diverse range of HB-HTA organizations with different structural levels exist in France for MD procurement linked to the category of hospitals. The study highlights the need for recognition of HB-HTA activity at the regulatory level in France and for direct collaboration between HTA activities performed at local and national levels.

Differential nanoscale organisation of LFA-1 modulates T-cell migration.

Effector T-cells rely on integrins to drive adhesion and migration to facilitate their immune function. The heterodimeric transmembrane integrin LFA-1 (αLß2 integrin) regulates adhesion and migration of effector T-cells through linkage of the extracellular matrix with the intracellular actin treadmill machinery. Here, we quantified the velocity and direction of F-actin flow in migrating T-cells alongside single-molecule localisation of transmembrane and intracellular LFA-1. Results showed that actin retrograde flow positively correlated and immobile actin negatively correlated with T-cell velocity. Plasma membrane-localised LFA-1 forms unique nano-clustering patterns in the leading edge, compared to the mid-focal zone, of migrating T-cells. Deleting the cytosolic phosphatase PTPN22, loss-of-function mutations of which have been linked to autoimmune disease, increased T-cell velocity, and leading-edge co-clustering of pY397 FAK, pY416 Src family kinases and LFA-1. These data suggest that differential nanoclustering patterns of LFA-1 in migrating T-cells may instruct intracellular signalling. Our data presents a paradigm where T-cells modulate the nanoscale organisation of adhesion and signalling molecules to fine tune their migration speed, with implications for the regulation of immune and inflammatory responses.This article has an associated First Person interview with the first author of the paper.

Quality of economic evaluations of drug-coated balloons and drug-eluting stents in peripheral artery disease: a systematic review.

OBJECTIVE: We aimed to perform a systematic review of economic evaluations of drug-coated balloons (DCBs) and drug-eluting stents (DESs) in peripheral artery disease (PAD) and to assess the level of evidence of relevant studies. The purpose was not to present economic findings. METHODS: A systematic review was performed using four electronic databases to identify health economic evaluation studies reporting on the use of DCBs and DESs in PAD. The methodological and reporting quality of the studies was assessed using three different tools, the Drummond, Cooper, and CHEERS (Consolidated Health Economic Evaluation Reporting Standards) checklists. RESULTS: Six articles were included in this review of the 1,728 publications identified. Four studies were cost-effectiveness analyses and two cost-utility analyses. According to the Cooper hierarchy scale, the studies used good-quality data sources. The level of evidence used for clinical effect sizes, safety data, baseline clinical data, and costs was of high quality in general. In contrast, an evaluation of the reporting quality suggested that essential information was lacking. CONCLUSION: The present study demonstrates that clinical data used in economic evaluations of DCBs and DESs in PAD are from clinical studies of high quality in general. However, the quality of reporting represents a concern when interpreting the results provided by these economic studies.

Evaluation of 3D printing costs in surgery: a systematic review.

OBJECTIVES: The use of three-dimensional (3D) printing in surgery is expanding and there is a focus on comprehensively evaluating the clinical impact of this technology. However, although additional costs are one of the main limitations to its use, little is known about its economic impact. The purpose of this systematic review is to identify the costs associated with its use and highlight the first quantitative data available. METHODS: A systematic literature review was conducted in the PubMed and Embase databases and in the National Health Service Economic Evaluation Database (NHS EED) at the University of York. Studies that reported an assessment of the costs associated with the use of 3D printing for surgical application and published between 2009 and 2019, in English or French, were included. RESULTS: Nine studies were included in our review. Nine types of costs were identified, the three main ones being printing material costs (n = 6), staff costs (n = 3), and operating room costs (n = 3). The printing cost ranged from less than U.S. dollars (USD) 1 to USD 146 (in USD 2019 values) depending on the criteria used to calculate this cost. Three studies evaluated the potential savings generated by the use of 3D printing technology in surgery, based on operating time reduction. CONCLUSION: This literature review highlights the lack of reliable economic data on 3D printing technology. Nevertheless, this review makes it possible to identify expenditures or items that should be considered in order to carry out more robust studies.

Quality of economic evaluations of ventricular assist devices: A systematic review.

OBJECTIVE: Because of a lack of suitable heart donors, alternatives to transplantation are required. These alternatives can have high costs. The aim of this study was to perform a systematic review of cost-effectiveness studies of ventricular assist devices (VADs) and to assess the level of evidence of relevant studies. The purpose was not to present economic findings. METHODS: A systematic review was performed using four electronic databases to identify health economic evaluation studies dealing with VADs. The methodological quality and reporting quality of the studies was assessed using three different tools, the Drummond, Cooper, and CHEERS (Consolidated Health Economic Evaluation Reporting Standards) checklists. RESULTS: Of the 1,258 publications identified, thirteen articles were included in this review. Twelve studies were cost-utility analyses and one was a cost-effectiveness analysis. According to the Cooper hierarchy scale, the quality of the data used was heterogeneous. The level of evidence used for clinical effect sizes, safety data, and baseline clinical data was of poor quality. In contrast, cost data were of high quality in most studies. Quality of reporting varied between studies, with an average score of 17.4 (range 15-19) according to the CHEERS checklist. CONCLUSION: The current study shows that the quality of clinical data used in economic evaluations of VADs is rather poor in general. This is a concern that deserves greater attention in the process of health technology assessment of medical devices.

The learning curve in transcatheter aortic valve implantation clinical studies: A systematic review.

BACKGROUND: Transcatheter aortic-valve implantation (TAVI) has become an essential alternative to surgical aortic-valve replacement in the treatment of symptomatic severe aortic stenosis, and this procedure requires technical expertise. The aim of this study was to identify prospective studies on TAVI from the past 10 years, and then to analyze the quality of information reported about the learning curve. MATERIALS AND METHODS: A systematic review of articles published between 2007 and 2017 was performed using PubMed and the EMBASE database. Prospective studies regarding TAVI were included. The quality of information reported about the learning curve was evaluated using the following criteria: mention of the learning curve, the description of a roll-in phase, the involvement of a proctor, and the number of patients suggested to maintain skills. RESULTS: A total of sixty-eight studies met the selection criteria and were suitable for analysis. The learning curve was addressed in approximately half of the articles (n = 37, 54 percent). However, the roll-in period was mentioned by only eight studies (12 percent) and with very few details. Furthermore, a proctorship was disclosed in three articles (4 percent) whereas twenty-five studies (37 percent) included authors that were proctors for manufacturers of TAVI. CONCLUSION: Many prospective studies on TAVI over the past 10 years mention learning curves as a core component of successful TAVI procedures. However, the quality of information reported about the learning curve is relatively poor, and uniform guidance on how to properly assess the learning curve is still missing.

HARMONIZING HEALTH TECHNOLOGY ASSESSMENT PRACTICES IN UNIVERSITY HOSPITALS: TO WHAT EXTENT IS THE MINI-HTA MODEL SUITABLE IN THE FRENCH CONTEXT?

BACKGROUND: The number of new medical devices for individual use that are launched annually exceeds the assessment capacity of the French national health technology assessment (HTA) agency. This has resulted in hospitals, and particularly university hospitals (UHs), developing hospital-based HTA initiatives to support their decisions for purchasing innovative devices. However, the methodologies used in such hospitals have no common basis. The aim of this study was to assess a mini-HTA model as a potential solution to harmonize HTA methodology in French UHs. METHODS: A systematic review was conducted on Medline, Embase, Health Technology Assessment database, and Google Scholar to identify published articles reporting the use of mini-HTA tools and decision support-like models. A survey was also carried out in eighteen French UHs to identify in-house decision support tools. Finally, topics evaluated in the Danish mini-HTA model and in French UHs were compared using Jaccard similarity coefficients. RESULTS: Our findings showed differences between topics evaluated in French UHs and those assessed in decision support models from the literature. Only five topics among the thirteen most evaluated in French UHs were similar to those assessed in the Danish mini-HTA model. The organizational and ethical/social impacts were rarely explored among the surveyed models used in French UHs when introducing new medical devices. CONCLUSIONS: Before its widespread and harmonized use in French UHs, the mini-HTA model would first require adaptations to the French context.

Combining multi-criteria decision analysis and mini-health technology assessment: A funding decision-support tool for medical devices in a university hospital setting.

BACKGROUND: At the hospital level, decisions about purchasing new and oftentimes expensive medical devices must take into account multiple criteria simultaneously. Multi-criteria decision analysis (MCDA) is increasingly used for health technology assessment (HTA). One of the most successful hospital-based HTA approaches is mini-HTA, of which a notable example is the Matrix4value model. OBJECTIVES: To develop a funding decision-support tool combining MCDA and mini-HTA, based on Matrix4value, suitable for medical devices for individual patient use in French university hospitals - known as the IDA tool, short for 'innovative device assessment'. METHODS: Criteria for assessing medical devices were identified from a literature review and a survey of 18 French university hospitals. Weights for the criteria, representing their relative importance, were derived from a survey of 25 members of a medical devices committee using an elicitation technique involving pairwise comparisons. As a test of its usefulness, the IDA tool was applied to two new drug-eluting beads (DEBs) for transcatheter arterial chemoembolization. RESULTS: The IDA tool comprises five criteria and weights for each of two over-arching categories: risk and value. The tool revealed that the two new DEBs conferred no additional value relative to DEBs currently available. CONCLUSIONS: Feedback from participating decision-makers about the IDA tool was very positive. The tool could help to promote a more structured and transparent approach to HTA decision-making in French university hospitals.

Innovative medical devices and hospital decision making: a study comparing the views of hospital pharmacists and physicians.

Objectives Many university hospitals have developed local health technology assessment processes to guide informed decisions about new medical devices. However, little is known about stakeholders' perceptions and assessment of innovative devices. Herein, we investigated the perceptions regarding innovative medical devices of their chief users (physicians and surgeons), as well as those of hospital pharmacists, because they are responsible for the purchase and management of sterile medical devices. We noted the evaluation criteria used to assess and select new medical devices and suggestions for improving local health technology assessment processes indicated by the interviewees. Methods We randomly selected 18 physicians and surgeons (nine each) and 18 hospital pharmacists from 18 French university hospitals. Semistructured interviews were conducted between October 2012 and August 2013. Responses were coded separately by two researchers. Results Physicians and surgeons frequently described innovative medical devices as 'new', 'safe' and 'effective', whereas hospital pharmacists focused more on economic considerations and considered real innovative devices to be those for which no equivalent could be found on the market. No significant difference in evaluation criteria was found between these groups of professionals. Finally, hospital pharmacists considered the management of conflicts of interests in local health technology assessment processes to be an issue, whereas physicians and surgeons did not. Conclusions The present study highlights differences in perceptions related to professional affiliation. The findings suggest several ways in which current practices for local health technology assessment in French university hospitals could be improved and studied. What is known about the topic? Hospitals are faced with ever-growing demands for innovative and costly medical devices. To help hospital management deal with technology acquisition issues, hospital-based health technology assessment has been developed to support decisions. However, little is known about the different perceptions of innovative medical devices among practitioners and how different perceptions may affect decision making. What does this paper add? This paper compares and understands the perceptions of two groups of health professionals concerning innovative devices in the university hospital environment. What are the implications for practitioners? Such a comparison of viewpoints could facilitate improvements in current practices and decision-making processes in local health technology assessment for these medical products.

INTRODUCTION OF INNOVATIVE MEDICAL DEVICES AT FRENCH UNIVERSITY HOSPITALS: AN OVERVIEW OF HOSPITAL-BASED HEALTH TECHNOLOGY ASSESSMENT INITIATIVES.

OBJECTIVES: Local health technology assessment (HTA) to determine whether new health technologies should be adopted is now a common practice in many healthcare organizations worldwide. However, little is known about hospital-based HTA activities in France. The objective of this study was to explore hospital-based HTA activities in French university hospitals and to provide a picture of organizational approaches to the assessment of new and innovative medical devices. METHODS: Eighteen semi-structured interviews with hospital pharmacists were conducted from October 2012 to April 2013. Six topics were discussed in depth: (i) the nature of the institution concerned; (ii) activities relating to innovative medical devices; (iii) the technology assessment and decision-making process; (iv) the methodology for technology assessment; (v) factors likely to influence decisions and (vi) suggestions for improving the current process. The interview data were coded, collated and analyzed statistically. RESULTS: Three major types of hospital-based HTA processes were identified: medical device committees, innovation committees, and "pharmacy & management" processes. HTA units had been set up to support medical device and innovation committees for technology assessment. Slow decision making was the main limitation to both these committee-based approaches. As an alternative, "pharmacy & management" processes emerged as a means of rapidly obtaining a formal assessment. CONCLUSIONS: This study provides an overview of hospital-based HTA initiatives in France. We hope that it will help to promote hospital-based HTA activities in France and discussions about ways to improve and harmonize practices, through the development of national guidelines and/or a French mini-HTA tool, for example.

Use of a risk assessment method to improve the safety of negative pressure wound therapy.

To conduct a risk analysis of the negative pressure wound therapy (NPWT) care process and to improve the safety of NPWT, a working group of nurses, hospital pharmacists, physicians and hospital managers performed a risk analysis for the process of NPWT care. The failure modes, effects and criticality analysis (FMECA) method was used for this analysis. Failure modes and their consequences were defined and classified as a function of their criticality to identify priority actions for improvement. By contrast to classical FMECA, the criticality index (CI) of each consequence was calculated by multiplying occurrence, severity and detection scores. We identified 13 failure modes, leading to 20 different consequences. The CI of consequences was initially 712, falling to 357 after corrective measures were implemented. The major improvements proposed included the establishment of 6-monthly training cycles for nurses, physicians and surgeons and the introduction of computerised prescription for NPWT. The FMECA method also made it possible to prioritise actions as a function of the criticality ranking of consequences and was easily understood and used by the working group. This study is, to our knowledge, the first to use the FMECA method to improve the safety of NPWT.

Hospital-based health technology assessment for innovative medical devices in university hospitals and the role of hospital pharmacists: learning from international experience.

OBJECTIVES: Several models of hospital-based health technology assessment (HTA) have been developed worldwide, for the introduction of innovative medical devices and support evidence-based decision making in hospitals. Two such models, the HTA unit and mini-HTA models, are widespread in university hospitals and involve various stakeholders. The purpose of this work was to highlight the potential role of hospital pharmacists in hospital-based HTA activities. METHODS: We searched for articles, reviews, and letters relating to hospital-based HTA, as defined by the Hospital-Based Health Technology Assessment Worldwide Survey published by the Health Technology Assessment International (HTAi) Society, in the Health Technology Assessment database, MEDLINE, EMBASE, and hospital pharmacy journals. RESULTS: The number of university hospitals performing hospital-based HTA has increased since the 2008 Hospital-Based Health Technology Assessment Worldwide Survey. Our own experience and international findings show that hospital pharmacists already contribute to hospital-based HTA activities and have developed study interpretation skills and a knowledge of medical devices. CONCLUSIONS: Promoting multidisciplinary approaches is one of the key success factors in hospital-based HTA. Hospital pharmacists occupy a position between hospital managers, clinicians, health economists, biomedical engineers, and patients and can provide a new perspective. In the future, hospital pharmacists are likely to become increasingly involved in hospital-based HTA activities.

Functionalized Lipid Droplets and Microfluidics Approach to Study Immune Cell Polarity In Vitro.

The study of lymphocyte polarization upon antigen encounter typically relies on the random pairing between the cells of interest and a stimulating particle (micro bead) that mimics only some of the properties of the antigen-presenting cells. Here, we show how to build and use a microfluidic chip that allows to multiplex and synchronize the encounter between a lymphocyte and an antigen-presenting object: a functionalized oil-in-water droplet. We also explain how to fabricate and functionalize lipid droplets, an antigen-presenting tool that is, at the same time, deformable, fluid, and spherical.

Polarity in immune cells.

Immune cells are responsible for pathogen detection and elimination, as well as for signaling to other cells the presence of potential danger. In order to mount an efficient immune response, they need to move and search for a pathogen, interact with other cells, and diversify the population by asymmetric cell division. All these actions are regulated by cell polarity: cell polarity controls cell motility, which is crucial for scanning peripheral tissues to detect pathogens, and recruiting immune cells to sites of infection; immune cells, in particular lymphocytes, communicate with each other by a direct contact called immunological synapse, which entails a global polarization of the cell and plays a role in activating lymphocyte response; finally, immune cells divide asymmetrically from a precursor, generating a diversity of phenotypes and cell types among daughter cells, such as memory and effector cells. This review aims at providing an overview from both biology and physics perspectives of how cell polarity shapes the main immune cell functions.

Microtubules restrict F-actin polymerization to the immune synapse via GEF-H1 to maintain polarity in lymphocytes.

Immune synapse formation is a key step for lymphocyte activation. In B lymphocytes, the immune synapse controls the production of high-affinity antibodies, thereby defining the efficiency of humoral immune responses. While the key roles played by both the actin and microtubule cytoskeletons in the formation and function of the immune synapse have become increasingly clear, how the different events involved in synapse formation are coordinated in space and time by actin-microtubule interactions is not understood. Using a microfluidic pairing device, we studied with unprecedented resolution the dynamics of the various events leading to immune synapse formation and maintenance in murine B cells. Our results identify two groups of events, local and global, dominated by actin and microtubules dynamics, respectively. They further highlight an unexpected role for microtubules and the GEF-H1-RhoA axis in restricting F-actin polymerization at the lymphocyte-antigen contact site, thereby allowing the formation and maintenance of a unique competent immune synapse.

Phenotyping polarization dynamics of immune cells using a lipid droplet-cell pairing microfluidic platform.

The immune synapse is the tight contact zone between a lymphocyte and a cell presenting its cognate antigen. This structure serves as a signaling platform and entails a polarization of intracellular components necessary to the immunological function of the cell. While the surface properties of the presenting cell are known to control the formation of the synapse, their impact on polarization has not yet been studied. Using functional lipid droplets as tunable artificial presenting cells combined with a microfluidic pairing device, we simultaneously observe synchronized synapses and dynamically quantify polarization patterns of individual B cells. By assessing how ligand concentration, surface fluidity, and substrate rigidity impact lysosome polarization, we show that its onset and kinetics depend on the local antigen concentration at the synapse and on substrate rigidity. Our experimental system enables a fine phenotyping of monoclonal cell populations based on their synaptic readout.

Pinching the cortex of live cells reveals thickness instabilities caused by myosin II motors.

The cell cortex is a contractile actin meshwork, which determines cell shape and is essential for cell mechanics, migration, and division. Because its thickness is below optical resolution, there is a tendency to consider the cortex as a thin uniform two-dimensional layer. Using two mutually attracted magnetic beads, one inside the cell and the other in the extracellular medium, we pinch the cortex of dendritic cells and provide an accurate and time-resolved measure of its thickness. Our observations draw a new picture of the cell cortex as a highly dynamic layer, harboring large fluctuations in its third dimension because of actomyosin contractility. We propose that the cortex dynamics might be responsible for the fast shape-changing capacity of highly contractile cells that use amoeboid-like migration.

Traction Force Microscopy to Study B Lymphocyte Activation.

Traction force microscopy (TFM) enables the measurement of forces produced by a cell on a substrate. This technique infers traction force measurements from an experimentally observed displacement field produced by a cell pulling on an elastic substrate. Here, we adapted TFM to investigate the spatial and temporal structure of the force field exerted by B cells when activated by antigen engagement of the B cell receptor. Gel rigidity, bead density, and protein functionalization must be optimized for the study of relatively small cells (~ 6 µm) that interact with, and respond specifically to ligands for cell surface receptors.