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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2007.12.045 Byline: C. Pouget (a), K. Pottin (a), T. Jaffredo (a)(b) Keywords: Avian embryo; Aorta; Somite; Vascular smooth muscle; Pericyte; PAX1; PAX3; FOXC2 Abstract: We previously demonstrated that progenitors of both endothelium and smooth muscle cells in the aortic wall originated from the somite in the trunk of the embryo. However whether the contribution to vascular Smooth Muscle Cells (vSMC) is restricted to the aorta or encompasses other vessels of the trunk is not known. Moreover, the somitic compartment that gives rise to vSMC is yet to be defined. Quail-chick orthotopic transplantations of either the segmental plate or the dorsal or ventral halves from single somites demonstrate that 1[degrees] vSMC of the body wall including those of the limbs originate from the somite. 2[degrees] Like vSMC, aortic pericytes originate from the somite. 3[degrees] The sclerotome is the somite compartment that gives rise to vSMC and pericytes. PAX1 and FOXC2, two molecular markers of the sclerotomal compartment, are expressed by vSMC and pericytes during the earliest phases of vascular wall formation. Later on, PDGFR-[beta] and MYOCARDIN are also expressed by these cells. In contrast, the dermomyotome gives rise to endothelium but never to cells in the vascular wall. Taken together, out data point out to the critical role of the somite in vessel formation and demonstrate that vSMC and endothelial cells originate from two independent somitic compartments. Author Affiliation: (a) Universite Pierre et Marie Curie-Paris 6, Bat C, 6eme etage, Case 24, 75252 Paris Cedex 05, France (b) CNRS UMR7622, Laboratoire de Biologie du Developpement, Bat C, 6eme etage, Case 24, 75252 Paris Cedex 05, France Article History: Received 13 August 2007; Revised 28 November 2007; Accepted 31 December 2007

In the context of designing innovative anticancer agents, the synthesis of a series of chalcones bearing a 3,4,5-trimethoxylated A ring and a variety of B rings, including phenols and original heterocycles such as chromones, was conducted. For this end, Claisen-Schmidt condensation was performed in basic or acidic conditions between the common starting material 3,4,5-trimethoxyacetophenone and appropriate aldehydes; this allowed the recovery of fifteen chalcones in moderate-good yields. The synthesized compounds were screened for their antiproliferative activity against colorectal and prostatic cancer cells, using a colorimetric MTT assay. Among the new chromonyl series, chalcone 13 demonstrates an interesting antiproliferative effect, with IC 50 values in the range of 2.6-5.1 µM at 48 h. Then, our study evidenced that indolyl chalcone 10 exhibits excellent activity towards the selected cell lines (with IC 50 less than 50 nM). This compound has already been described and has been shown to be a potent anticancer agent against other cancer cell lines. Our investigations highlighted apoptosis induction, through several pro-apoptotic markers, of these two heterocyclic chalcones. Considering phenolic chalcones, compounds 2 and 8 were found to be the most active against cell proliferation, exerting their effect by inducing the depolymerization of cell microtubules. The most promising compounds in this series will be selected for application in a strategy of vectorization by either active or passive targeting.

Promptly identifying threatening stimuli is crucial for survival. Freezing is a natural behavior displayed by rodents toward potential or actual threats. Although it is known that the prelimbic cortex (PL) is involved in both risk evaluation and in fear and anxiety-like behavior expression, here we explored whether PL neuronal activity can dynamically represent different internal states of the same behavioral output (i.e., freezing). We found that freezing can always be decoded from PL activity at a population level. However, the sudden presentation of a fearful stimulus quickly reshaped the PL to a new neuronal activity state, an effect not observed in other cortical or subcortical regions examined. This shift changed PL freezing representation and is necessary for fear memory expression. Our data reveal the unique role of the PL in detecting threats and internally adjusting to distinguish between different freezing-related states in both unconditioned and conditioned fear representations., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Amino acid PET is recommended for the initial diagnosis of brain lesions, but its value for identifying aggressive lesions remains to be established. The current study therefore evaluates the added-value of dynamic [18 F]FDOPA PET as an adjunct to conventional MRI for determining the aggressiveness of presumed glial lesions at diagnosis., Methods: Consecutive patients, with a minimal 1 year-follow-up, underwent contrast-enhanced MRI (CE MRI) and dynamic [18 F]FDOPA PET to characterize their suspected glial lesion. Lesions were classified semi-automatically by their CE MRI (MRI-/+), and PET parameters (static tumor-to-background ratio, TBR; dynamic time-to-peak ratio, TTP ratio ). Diagnostic accuracies of MRI and PET parameters for the differentiation of tumor aggressiveness were evaluated by chi-square test or receiver operating characteristic analyses. Aggressive lesions were either defined as lesions with dismal molecular characteristics based on the WHO 2021 classification of brain tumors or with compatible clinico-radiological profiles. Time-to-treatment failure (TTF) and overall survival (OS) were evaluated., Results: Of the 109 patients included, 46 had aggressive lesions (45 confirmed by histo-molecular analyses). CE MRI identified aggressive lesions with an accuracy of 73%. TBR max (threshold of 3.2), and TTP ratio (threshold of 5.4 min) respectively identified aggressive lesions with an accuracy of 83% and 76% and were independent of CE MRI and clinical factors in the multivariate analysis. Among the MRI-lesions, 11/56 (20%) were aggressive and respectively 55% and 50% of these aggressive lesions showed high TBR max and short TTP ratio in PET. High TBR max and short TTP ratio in PET were significantly associated to poorer survivals (p ≤ 0.009)., Conclusion: Dynamic [18 F]FDOPA PET provides a similar diagnostic accuracy as contrast enhancement in MRI to identify the aggressiveness of suspected glial lesions at diagnosis. Both methods, however, are complementary and [18 F]FDOPA PET may be a useful additional tool in equivocal cases., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The first hematopoietic stem and progenitor cells (HSPCs) emerge in the Aorta-Gonad-Mesonephros (AGM) region of the mid-gestation mouse embryo. However, the precise nature of their supportive mesenchymal microenvironment remains largely unexplored. Here, we profiled transcriptomes of laser micro-dissected aortic tissues at three developmental stages and individual AGM cells. Computational analyses allowed the identification of several cell subpopulations within the E11.5 AGM mesenchyme, with the presence of a yet unidentified subpopulation characterized by the dual expression of genes implicated in adhesive or neuronal functions. We confirmed the identity of this cell subset as a neuro-mesenchymal population, through morphological and lineage tracing assays. Loss of function in the zebrafish confirmed that Decorin, a characteristic extracellular matrix component of the neuro-mesenchyme, is essential for HSPC development. We further demonstrated that this cell population is not merely derived from the neural crest, and hence, is a bona fide novel subpopulation of the AGM mesenchyme., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

Background: The transition from colonization to invasion is critical in diabetic foot ulcer (DFU). Staphylococcus aureus can colonize DFU, or invade the underlying tissues, causing serious infections. The ROSA-like prophage has previously been implicated in strain colonization characteristics of S aureus isolates in uninfected ulcers., Methods: In this study, we investigated this prophage in the S aureus-colonizing strain using an in vitro chronic wound medium mimicking the chronic wound environment., Results: Chronic wound medium reduced bacterial growth and increased biofilm formation and virulence in a zebrafish model., Conclusions: The ROSA-like prophage promoted intracellular survival of S aureus-colonizing strain in macrophages, keratinocytes, and osteoblasts., Competing Interests: Potential conflicts of interest. All authors: No reported conflicts of interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Colon cancer poses a complex and substantial global health challenge, necessitating innovative therapeutic approaches. Chalcones, a versatile class of compounds with diverse pharmacological properties, have emerged as promising candidates for addressing colon cancer. Their ability to modulate pivotal signaling pathways in the development and progression of colon cancer makes them invaluable as targeted therapeutics. Nevertheless, it is crucial to recognize that although chalcones exhibit promise, further pre-clinical studies are required to validate their efficacy and safety. The journey toward effective colon cancer treatment is multifaceted, involving considerations such as optimizing the sequencing of therapeutic agents, comprehending the resistance mechanisms, and exploring combination therapies incorporating chalcones. Furthermore, the integration of nanoparticle-based drug delivery systems presents a novel avenue for enhancing the effectiveness of chalcones in colon cancer treatment. This review delves into the mechanisms of action of natural chalcones and some derivatives. It highlights the challenges associated with their use in pre-clinical studies, while also underscoring the advantages of employing chalcone-based nanoparticles for the treatment of colon cancer.

Daptomycin (DAP) represents an interesting alternative to treat methicillin-resistant Staphylococcus aureus (MRSA) infections. Different mechanisms of DAP resistance have been described; however, in vivo-acquired resistance is uncharacterized. This study described the phenotypic and genotypic evolution of MRSA strains that became resistant to DAP in two unrelated patients with bacteremia under DAP treatment, in two hospitals in the South of France. DAP MICs were determined using broth microdilution method on the pairs of isogenic (DAP-S/DAP-R) S. aureus isolated from bloodstream cultures. Whole genome sequencing was carried out using Illumina MiSeq Sequencing system. The two cases revealed DAP-R acquisition by MRSA strains within three weeks in patients treated by DAP. The isolates belonged to the widespread ST5 (patient A) and ST8 (patient B) lineages and were of spa -type t777 and t622, respectively. SNP analysis comparing each DAP-S/DAP-R pair confirmed that the isolates were isogenic. The causative mutations were identified in MprF (Multiple peptide resistance Factor) protein: L826F (Patient A) and S295L (Patient B), and in Cls protein: R228H (Patient B). These proteins encoded both proteins of the lipid biosynthetic enzymes. The resistance to DAP is particularly poorly described whereas DAP is highly prescribed to treat MRSA. Our study highlights the non-systematic cross-resistance between DAP and glycopeptides and the importance of monitoring DAP MIC in persistent MRSA bacteremia.

Introduction: Odontogenic myxoma is a relatively rare bone tumor involving exclusively the jaws. Despite its benign nature, odontogenic myxoma can exhibit aggressive, locally invasiveness and has a high potential of recurrence. Surgical treatment can be conservative of radical. The choice of surgical procedure is controversial, and there are no established guidelines., Case Series Presentation: We present a case series of three cases of odontogenic myxomas. This case series illustrates the variability of the radioclinical presentation of odontogenic myxoma and the resulting surgical management, ranging from simple enucleation to mandibular interruptive resection surgery with free flap reconstruction., Discussion and Conclusion: Through this case series, we highlighted and described decision criteria contributing to treatment choice and summarized this in an algorithm. Radiological tumor characteristics and also patient specific factors such as age need to be considered to make a personalized decision to each patient., Competing Interests: Conflict of interest statement All authors declare that there are no financial and personal relationships with other people or organizations that could inappropriately influence their work., (Copyright © 2023. Published by Elsevier Ltd.)

Development of the dorsal aorta is a key step in the establishment of the adult blood-forming system, since hematopoietic stem and progenitor cells (HSPCs) arise from ventral aortic endothelium in all vertebrate animals studied. Work in zebrafish has demonstrated that arterial and venous endothelial precursors arise from distinct subsets of lateral plate mesoderm. Here, we profile the transcriptome of the earliest detectable endothelial cells (ECs) during zebrafish embryogenesis to demonstrate that tissue-specific EC programs initiate much earlier than previously appreciated, by the end of gastrulation. Classic studies in the chick embryo showed that paraxial mesoderm generates a subset of somite-derived endothelial cells (SDECs) that incorporate into the dorsal aorta to replace HSPCs as they exit the aorta and enter circulation. We describe a conserved program in the zebrafish, where a rare population of endothelial precursors delaminates from the dermomyotome to incorporate exclusively into the developing dorsal aorta. Although SDECs lack hematopoietic potential, they act as a local niche to support the emergence of HSPCs from neighboring hemogenic endothelium. Thus, at least three subsets of ECs contribute to the developing dorsal aorta: vascular ECs, hemogenic ECs, and SDECs. Taken together, our findings indicate that the distinct spatial origins of endothelial precursors dictate different cellular potentials within the developing dorsal aorta., Competing Interests: PS, CP, SE, OS, JC, LG, TG, DT No competing interests declared, (© 2023, Sahai-Hernandez, Pouget, Eyal et al.)

Gene fusions and MET exon skipping drive oncogenesis in 8-9% and 3% of non-small cell lung cancers (NSCLC) respectively. Their detection are essential for the management of patients since they confer sensitivity to specific targeted therapies with significant clinical benefit over conventional chemotherapy. Immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) account for historical reference techniques however molecular-based technologies (RNA-based sequencing and RT-PCR) are emerging as alternative or complementary methods. Here, we evaluated the analytical performance of the fully-automated RT-PCR Idylla GeneFusion assay compared to reference methods using 35 fixed NSCLC samples. Idylla demonstrated overall agreement, sensitivity and specificity of 100% compared to RNASeq. Interestingly, it succeeded in retrieving 10 out of 11 samples with inconclusive results due to insufficient RNA quality for sequencing. Idylla showed an overall agreement, sensitivity and specificity of 90.32%, 91.67% and 89.47% compared to IHC/FISH respectively. Using commercial standards, the limit of detection of the Idylla system for the most frequent fusions and exon skipping ranges between 5 and 10 ng RNA input. These results support that the Idylla assay is a reliable and rapid option for the detection of these alterations, however a particular attention is needed for the interpretation of the expression imbalance., (© 2023. Springer Nature Limited.)

Background: Diabetic foot infections (DFIs) represent a public health problem because of their frequency and the severity of their consequences, i.e. amputation and mortality. Polymicrobial biofilms on the skin surface of these ulcers complicate wound healing. Few in vitro models exist to study the antibiotics activity in this context., Objectives: This study evaluated the in vitro activity of antibiotics against the two main bacteria isolated in DFI, Staphylococcus aureus and Pseudomonas aeruginosa, using a dynamic system (BioFlux™ 200) and a chronic wound-like medium (CWM) that mimic the foot ulcer environment., Methods: Reference strains and two pairs of clinical S. aureus and P. aeruginosa isolated together from a DFI were cultivated in brain heart infusion and CWM media during 72 h at 37°C, alone and combined in the BioFlux™ 200 system. Antibiotic activity was evaluated after a mechanical debridement. The activities were measured by the reduction of biofilm percentage of bacteria in the microfluidic system using microscopy., Results: Daptomycin for S. aureus and ceftazidime for P. aeruginosa showed excellent activity to reduce biofilm biomass, whereas linezolid action was more mitigated and dalbavancin was ineffective. Ceftazidime + daptomycin presented the most potent in vitro activity on a mixed biofilm., Conclusions: The combination of CWM and the BioFlux™ microfluidic system represents a valuable tool to screen the potential antimicrobial activity of antibiotics under conditions mimicking those encountered in DFI. It could help clinicians in their management of chronic wounds., (© The Author(s) 2022. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Coagulase-negative staphylococci (CoNS) and especially Staphylococcus epidermidis are responsible for health care infections, notably in the presence of foreign material (e.g., venous or central-line catheters). Catheter-related bacteremia (CRB) increases health care costs and mortality. The aim of our study was to evaluate the impact of 15 days of antibiotic exposure (ceftobiprole, daptomycin, linezolid and vancomycin) at sub-inhibitory concentration on the resistance, fitness and genome evolution of 36 clinical strains of S. epidermidis responsible for CRB. Resistance was evaluated by antibiogram, the ability to adapt metabolism by the Biofilm Ring test ® and the in vivo nematode virulence model. The impact of antibiotic exposure was determined by whole-genome sequencing (WGS) and biofilm formation experiments. We observed that S. epidermidis strains presented a wide variety of virulence potential and biofilm formation. After antibiotic exposure, S. epidermidis strains adapted their fitness with an increase in biofilm formation. Antibiotic exposure also affected genes involved in resistance and was responsible for cross-resistance between vancomycin, daptomycin and ceftobiprole. Our data confirmed that antibiotic exposure modified bacterial pathogenicity and the emergence of resistant bacteria.

Meningiomas are the most common primary tumors of the central nervous system. Based on the 2021 WHO classification, they are classified into three grades reflecting recurrence risk and aggressiveness. However, the WHO's histopathological criteria defining these grades are somewhat subjective. Together with reliable immunohistochemical proliferation indices, other molecular markers such as those studied with genome-wide epigenetics promise to revamp the current prognostic classification. In this study, 48 meningiomas of various grades were randomly included and explored for DNA methylation with the Infinium MethylationEPIC microarray over 850k CpG sites. We conducted differential and correlative analyses on grade and several proliferation indices and markers, such as mitotic index and Ki-67 or MCM6 immunohistochemistry. We also set up Cox proportional hazard models for extensive associations between CpG methylation and survival. We identified loci highly correlated with cell growth and a targeted methylation signature of regulatory regions persistently associated with proliferation, grade, and survival. Candidate genes under the control of these regions include SMC4 , ESRRG , PAX6 , DOK7 , VAV2 , OTX1 , and PCDHA - PCDHB - PCDHG , i.e., the protocadherin gene clusters. This study highlights the crucial role played by epigenetic mechanisms in shaping dysregulated cellular proliferation and provides potential biomarkers bearing prognostic and therapeutic value for the clinical management of meningioma.

Staphylococcus pettenkoferi is a recently described coagulase-negative Staphylococcus identified in human diseases, especially in infections of foot ulcers in patients living with diabetes mellitus. To date, its pathogenicity remains underexplored. In this study, whole-genome analysis was performed on a collection of 29 S. pettenkoferi clinical strains isolated from bloodstream and diabetic foot infections with regard to their phylogenetic relationships and comprehensive analysis of their resistome and virulome. Their virulence was explored by their ability to form biofilm, their growth kinetics and in an in vivo zebrafish embryo infection model. Our results identified two distinct clades (I and II) and two subclades (I-a and I-b) with notable genomic differences. All strains had a slow bacterial growth. Three profiles of biofilm formation were noted, with 89.7% of isolates able to produce biofilm and harbouring a high content of biofilm-encoding genes. Two virulence profiles were also observed in the zebrafish model irrespective of the strains' origin or biofilm profile. Therefore, this study brings new insights in S. pettenkoferi pathogenicity.

In diabetic foot ulcers (DFUs), biofilm formation is a major challenge that promotes wound chronicity and delays healing. Antiseptics have been proposed to combat biofilms in the management of DFUs. However, there is limited evidence on the activity of these agents against biofilms, and there are questions as to which agents have the best efficiency. Here, we evaluated the antibiofilm activity of sodium hypochlorite, polyvinylpyrrolidoneIodine (PVPI), polyhexamethylenebiguanide (PHMB) and octenidine against Pseudomonas aeruginosa strains using static and dynamic systems in a chronic-wound-like medium (CWM) that mimics the chronic wound environment. Using Antibiofilmogram ® , a technology assessing the ability of antiseptics to reduce the initial phase of biofilm formation, we observed the significant activity of antiseptics against biofilm formation by P. aeruginosa (at 1:40 to 1:8 dilutions). Moreover, 1:100 to 1:3 dilutions of the different antiseptics reduced mature biofilms formed after 72 h by 10-log, although higher concentrations were needed in CWM (1:40 to 1:2). Finally, in the BioFlux200 TM model, after biofilm debridement, sodium hypochlorite and PHMB were the most effective antiseptics. In conclusion, our study showed that among the four antiseptics tested, sodium hypochlorite demonstrated the best antibiofilm activity against P. aeruginosa biofilms and represents an alternative in the management of DFUs.

Biofilm on the skin surface of chronic wounds is an important step that involves difficulties in wound healing. The polymicrobial nature inside this pathogenic biofilm is key to understanding the chronicity of the lesion. Few in vitro models have been developed to study bacterial interactions inside this chronic wound. We evaluated the biofilm formation and the evolution of bacteria released from this biofilm on the two main bacteria isolated in this condition, Staphylococcus aureus and Pseudomonas aeruginosa, using a dynamic system (BioFlux™ 200) and a chronic wound-like medium (CWM) that mimics the chronic wound environment. We observed that all species constituted a faster biofilm in the CWM compared to a traditional culture medium (p < 0.01). The percentages of biofilm formation were significantly higher in the mixed biofilm compared to those determined for the bacterial species alone (p < 0.01). Biofilm organization was a non-random structure where S. aureus aggregates were located close to the wound surface, whereas P. aeruginosa was located deeper in the wound bed. Planktonic biofilm-detached bacteria showed decreased growth, overexpression of genes encoding biofilm formation, and an increase in the mature biofilm biomass formed. Our data confirmed the impact of the chronic wound environment on biofilm formation and on bacterial lifecycle inside the biofilm.

Chronic wounds, defined by their resistance to care after four weeks, are a major concern, affecting millions of patients every year. They can be divided into three types of lesions: diabetic foot ulcers (DFU), pressure ulcers (PU), and venous/arterial ulcers. Once established, the classical treatment for chronic wounds includes tissue debridement at regular intervals to decrease biofilm mass constituted by microorganisms physiologically colonizing the wound. This particular niche hosts a dynamic bacterial population constituting the bed of interaction between the various microorganisms. The temporal reshuffle of biofilm relies on an organized architecture. Microbial community turnover is mainly associated with debridement (allowing transitioning from one major representant to another), but also with microbial competition and/or collaboration within wounds. This complex network of species and interactions has the potential, through diversity in antagonist and/or synergistic crosstalk, to accelerate, delay, or worsen wound healing. Understanding these interactions between microorganisms encountered in this clinical situation is essential to improve the management of chronic wounds.

The International Society for the Study of Vascular Anomalies (ISSVA) has defined four vascular lesions in the central nervous system (CNS): arteriovenous malformations, cavernous angiomas (also known as cerebral cavernous malformations), venous malformations, and telangiectasias. From a retrospective central radiological and histopathological review of 202 CNS vascular lesions, we identified three cases of unclassified vascular lesions. Interestingly, they shared the same radiological and histopathological features evoking the cavernous subtype of angioleiomyomas described in the soft tissue. We grouped them together with four additional similar cases from our clinicopathological network and performed combined molecular analyses. In addition, cases were compared with a cohort of 5 soft tissue angioleiomyomas. Three out 6 CNS lesions presented the same p.Gly41Cys GJA4 mutation recently reported in hepatic hemangiomas and cutaneous venous malformations and found in 4/5 soft tissue angioleiomyomas of our cohort with available data. Most DNA methylation profiles were not classifiable using the CNS brain tumor (version 12.5), and sarcoma (version 12.2) classifiers. However, using unsupervised t-SNE analysis and hierarchical clustering analysis, 5 of the 6 lesions grouped together and formed a distinct epigenetic group, separated from the clusters of soft tissue angioleiomyomas, other vascular tumors, inflammatory myofibroblastic tumors and meningiomas. Our extensive literature review identified several cases similar to these lesions, with a wide variety of denominations. Based on radiological and histomolecular findings, we suggest the new terminology of "dural angioleiomyomas" (DALM) to designate these lesions characterized by a distinct DNA methylation pattern and frequent GJA4 mutations., (© 2022. The Author(s).)

Biofilm on the skin surface of chronic wounds is an important factor in the pathology, inhibiting wound healing. The polymicrobial nature of these infected wounds and bacterial interactions inside this pathogenic biofilm are the keys for understanding chronic infection. The aim of our work was to develop an innovative in vitro medium that closely mimics the chronic wound emphasizing the microbiological, cellular, and inflammatory environment of chronic wounds but also focusing on the pH found at the wound level. This new medium, called chronic wound medium (CWM), will thus facilitate the study of pathogenic biofilm organization. Clinical Staphylococcus aureus and Pseudomonas aeruginosa strains coisolated from diabetic foot infection were collected and cultivated in this new medium for 24 h in monoculture and coculture. Bacterial growth (growth curves), presence of small colony variant (SCV), biofilm formation (BioFilm Ring Test ® assay, biofilm biomass quantification), and virulence (survival curve in a Caenorhabditis elegans model) were evaluated. After 24 h in the in vitro conditions, we observed that P. aeruginosa growth was not affected, compared with a control bacterial medium, whereas for S. aureus , the stationary phase was reduced by two logs. Interestingly, S. aureus growth increased when cocultured with P. aeruginosa in CWM. In coculture with P. aeruginosa , SCV forms of S. aureus were detected. Biofilm studies showed that bacteria, alone and in combination, formed biofilm faster (as soon as 3 h) than the bacteria exposed in a control medium (as soon as 5 h). The virulence of all strains decreased in the nematode model when cultivated in our new in vitro medium. Taken together, our data confirmed the impact of the chronic wound environment on biofilm formation and bacteria virulence. They indicated that P. aeruginosa and S. aureus cooperated in coinfected wounds. Therefore, this in vitro model provides a new tool for bacterial cooperation investigation and polymicrobial biofilm formation., Competing Interests: The authors were co-inventors of the CWM (European patent application EP21305337, filed on 18 March 2021). CPo was the recipient of a grant from Biofilm Pharma (Bourse CIFRE). CPo, TB, CPr, and JT were employed by Biofilm Pharma SAS., (Copyright © 2022 Pouget, Dunyach-Remy, Bernardi, Provot, Tasse, Sotto and Lavigne.)