The loss of elasticity is a hallmark of systemic aging or genetic syndromes (e.g. cutis laxa, Williams-Beuren and supravalvular aortic stenosis) with direct consequences on tissue functions, and particularly deleterious when associated to the cardiovascular system. Tissue elasticity is mainly provided by large elastic fibers composed of supramolecular complexes of elastin and microfibrils. In arteries, the mature elastic fibers are located in the media compartment and form concentric elastic lamellar units together with the smooth muscle cells (SMCs). The main function of vascular elastic fibers is to allow extension and recoil of the vessel walls in response to the intraluminal pressure generated by the blood flow following cardiac systole. The synthesis of elastic fibers (elastogenesis) mainly occurs during the last third of fetal life with a peak in the perinatal period and then slowly decreases until the end of growth; as a result, elastic fiber repair is almost non-existent in adults. To date, no treatment exists to restore or repair deficient or degraded elastic fibers. A few pharmacological compounds have been proposed, but their efficacy/side effects balance remains very unfavorable. As an alternative strategy, we developed a synthetic elastic protein (SEP) inspired by the human tropoelastin, the elastin soluble precursor, to provide an elastic molecular prosthesis capable of integrating and reinforcing endogenous elastic fibers. The SEP was easily produced in E. coli and purified by inversed transition cycling method. The resulting 55 kDa protein recapitulates the main physicochemical properties of the tropoelastin as thermal responsiveness, intrinsically disordered structures, and spherical self-assembly. The cross-linked SEP displays linear elastic mechanical properties under uniaxial tension loads. Using a co-culture in vitro model of the endothelial barrier, our results show that SEP is able to cross the cohesive endothelial monolayer to reach underlying SMCs. Moreover, SEP is processed by SMCs through a lysyl oxidase-dependent mechanism to form fibrillar structures that colocalize with fibrillin-rich microfibrils. The SEP was further characterized in vivo through the zebrafish model. The results indicate a global innocuity on zebrafish embryos and an absence of neutrophil recruitment following injection into the yolk sac of zebrafish. Finally, intravenous injection of a fluorescent SEP highlights its deposition in the wall of tortuous vessels which persists for several days after injection of the larvae. Taken together, our results demonstrate for the first time the incorporation of a naked tropoelastin-bioinspired polypeptide in endogenous elastic fibrillar deposits from SMCs, and its recognition by the lysyl- oxidase enzymatic machinery. In absence of toxicity and proinflammatory signal combined to a long-lasting accumulation in vessels in vivo , the SEP fulfills the first prerequisites for the development of an original biotherapeutic compound addressing the repair of elastic fibers.

Background: The process by which functional elastic fibers are produced, namely elastogenesis, is complex and difficult to assess in vitro. Identifying efficient elasticity‐boosting ingredients thus represents a challenge. Aims: The elasticity‐boosting properties of a novel extract of Murraya koenigii leafy stems were assessed in vitro in 3D culture models before being evaluated in human female volunteers. Methods: Synthesis of elastic fiber related proteins was evaluated in a skin‐equivalent model. Using multiphoton microscopy, the structural organization of elastin deposits was studied within a scaffold‐free dermal microtissue. Biomechanical properties of the 3D microtissue were also measured by atomic force microscopy. In vivo, fringe‐projection and image analysis were used to evaluate nasogenian fold severity in a panel of Caucasian female volunteers. The impact of gravity on visible signs of facial aging was assessed by clinical scoring carried out alternatively in the supine and sitting positions. Results: We showed the Murraya koenigii extract increased protein expressions of elastin and fibrillin‐1 in a 3D skin equivalent model. Using scaffold‐free dermal microtissue, we confirmed that Murraya koenigii extract allowed a proper and ordered network of elastin deposits and consequently improved tissue elasticity. Clinical data showed that a twice‐daily application for 98 days of the extract formulated at 1% allowed to visibly reduce nasogenian fold severity, jowl severity and to mitigate the impact of gravity on the facial signs of aging. Conclusion: The newly discovered extract of Murraya koenigii leafy stems represents an innovative antiaging ingredient suited for elasticity‐boosting and antisagging claims.

Dark circles are a cosmetic concern worldwide, often associated with tiredness or aging. Owing to its thinness, the highly vascularized eye conto | POSTER

Spheroids as microtissues are a powerful alternative to standard 2D cell culture for in vitro studies. 3D scaffold-free spheroids are formed within a few days from a cell suspension using hanging drop technology. The advantages of spheroids exclusively composed of fibroblasts rely on the physiological production of the extracellular matrix thanks to the aggregative capability of

The loss of elasticity is a characteristic feature of skin aging. Indeed, elastic fibers are poorly renewed and are degraded much quicker than synthesized. To compensate for this imbalance, a unique extract from the traditional ayurvedic plant Murraya koenigii was developed. First, a proteomic study combined with bioinformatics, revealed that monolayer cultures of human dermal

Les peptides élastiques (ELP, Elastin-like peptide) sont d'excellents exemples de polymères biomimétiques récemment proposés en médecine régénérative, en particulier dans le domaine de l'ingénierie tissulaire des tissus mous (peau, vaisseaux sanguins, poumons…) pour lesquels la modélisation est complexe car l'instruction correcte des cellules nécessite une élasticité fonctionnelle. L'ajustement précis de la structure primaire des ELP peut moduler voire améliorer les propriétés physico-chimiques, structurales et fonctionnelles de la protéine native. De plus, la capacité des ELP à ajuster leurs caractéristiques physico-chimiques en réponse à des stimuli externes (température, pH), les définit comme des polymères intelligents. Ces polymères bioactifs offrent ainsi une large gamme d'applications très prometteuses encore très peu explorées dans les technologies d'ingénierie tissulaire et les systèmes d'administration de médicaments. Dans ce travail de thèse, nous avons développé, caractérisé et évalué les potentiels thérapeutiques d'une protéine élastique synthétique, Elactiv', inspirée de la structure unique de la tropoélastine humaine, précurseur soluble de l'élastine. Elactiv' conserve les caractéristiques physico-chimiques (comportement thermosensible, propriétés d'autoassemblage) et les fonctions biologiques de la protéine native (prolifération, différenciation et survie des fibroblastes dermiques et kératinocytes humains, sensibilité à la dégradation enzymatique). De plus, Elactiv' possède la particularité in vitro de s'incorporer dans les fibres élastiques néo-synthétisées par des fibroblastes dermiques sains, et d'induire la synthèse de tropoélastine fibrillaire par des fibroblastes pathologiques, syndrome de Williams-Beuren, qui ne synthétisent pas ou très peu de fibres élastiques. Un hydrogel formé exclusivement d'Elactiv' a permis d'accéder aux propriétés mécaniques de l'ensemble et de vérifier sa biocompatibilité in vitro et son innocuité et sa résorption in vivo. Enfin, l'association de la protéine Elactiv' aux dendrigrafts de poly(L-lysine), polymères synthétiques hautement fonctionnalisables, a permis de faire évoluer l'architecture de l'hydrogel vers un biomatériau hybride dans le but d'augmenter ses propriétés mécaniques et biologiques. Ainsi, les potentiels biomimétiques et thérapeutiques de la protéine Elactiv' en font un candidat prometteur pour la régénération des tissus mous