Plants as a cost-effective source for customizable photosynthetic wound dressings: A proof of concept study.

Oxygen is essential for tissue regeneration, playing a crucial role in several processes, including cell metabolism and immune response. Therefore, the delivery of oxygen to wounds is an active field of research, and recent studies have highlighted the potential use of photosynthetic biomaterials as alternative oxygenation approach. However, while plants have traditionally been used to enhance tissue regeneration, their potential to produce and deliver local oxygen to wounds has not yet been explored. Hence, in this work we studied the oxygen-releasing capacity of Marchantia polymorpha explants, showing their capacity to release oxygen under different illumination settings and temperatures. Moreover, co-culture experiments revealed that the presence of these explants had no adverse effects on the viability and morphology of fibroblasts in vitro, nor on the viability of zebrafish larvae in vivo. Furthermore, oxygraphy assays demonstrate that these explants could fulfill the oxygen metabolic requirements of zebrafish larvae and freshly isolated skin biopsies ex vivo. Finally, the biocompatibility of explants was confirmed through a human skin irritation test conducted in healthy volunteers following the ISO-10993-10-2010. This proof-of-concept study provides valuable scientific insights, proposing the potential use of freshly isolated plants as biocompatible low-cost oxygen delivery systems for wound healing and tissue regeneration.

Microalgae share key features with human erythrocytes and can safely circulate through the vascular system in mice.

As animal cells cannot produce oxygen, erythrocytes are responsible for gas interchange, being able to capture and deliver oxygen upon tissue request. Interestingly, several other cells in nature produce oxygen by photosynthesis, raising the question of whether they could circulate within the vascular networks, acting as an alternative source for oxygen delivery. To address this long-term goal, here some physical and mechanical features of the photosynthetic microalga Chlamydomona reinhardtii were studied and compared with erythrocytes, revealing that both exhibit similar size and rheological properties. Moreover, key biocompatibility aspects of the microalgae were evaluated in vitro and in vivo, showing that C. reinhardtii can be co-cultured with endothelial cells, without affecting each other's morphology and viability. Moreover, short-term systemic perfusion of the microalgae showed a thoroughly intravascular distribution in mice. Finally, the systemic injection of high numbers of microalgae did not trigger deleterious responses in living mice. Altogether, this work provides key scientific insights to support the notion that photosynthetic oxygenation could be achieved by circulating microalgae, representing another important step towards human photosynthesis. KEY POINTS: • C. reinhardtii and endothelial cells are biocompatible in vitro. • C. reinhardtii distribute throughout the entire vasculature after mice perfusion. • C. reinhardtii do not trigger deleterious responses after injection in mice.

Development of an implantable three-dimensional model of a functional pathogenic multispecies biofilm to study infected wounds.

Chronic wounds cannot heal due to impairment of regeneration, mainly caused by the persistent infection of multispecies biofilms. Still, the effects of biofilm wound infection and its interaction with the host are not fully described. We aimed to study functional biofilms in physiological conditions in vitro, and their potential effects in health and regeneration in vivo. Therefore, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis were seeded in collagen-based scaffolds for dermal regeneration. After 24 h, scaffolds had bacterial loads depending on the initial inoculum, containing viable biofilms with antibiotic tolerance. Afterwards, scaffolds were implanted onto full skin wounds in mice, together with daily supervision and antibiotic treatment. Although all mice survived their health was affected, displaying fever and weight loss. After ten days, histomorphology of scaffolds showed high heterogeneity in samples and within groups. Wounds were strongly, mildly, or not infected according to colony forming units, and P. aeruginosa had higher identification frequency. Biofilm infection induced leucocyte infiltration and elevated interferon-γ and interleukin-10 in scaffolds, increase of size and weight of spleen and high systemic pro-calcitonin concentrations. This functional and implantable 3D biofilm model allows to study host response during infection, providing a useful tool for infected wounds therapy development.

Dietas vegetarianas en niños: conocimientos de pediatras de la Sociedad Uruguaya de Pediatría: encuesta 2020 / Vegetarian diet in children: pediatric knowledge from the Uruguayan Society of Pediatrics: 2020 survey / Dietas vegetarianas em crianças: conhecimento dos pediatras da Sociedade Uruguaia de Pediatria: inquérito 2020

Introducción: en los últimos años el incremento de vegetarianos es considerable. Se debe tener cautela al incorporar este tipo de dietas en la población pediátrica. No son contempladas en las actuales guías de nutrición nacionales, generando incertidumbre al realizar recomendaciones. Objetivo: describir los conocimientos sobre dietas vegetarianas en niños por parte de médicos pediatras, posgrados y residentes socios de la Sociedad Uruguaya de Pediatría en el período de junio-setiembre 2020. Determinar la necesidad de incorporar dietas vegetarianas a las guías uruguayas de nutrición pediátrica por parte de los encuestados. Material y método: estudio observacional descriptivo, tipo encuesta transversal, en el período entre junio y setiembre de 2020. Los criterios de inclusión fueron médicos residentes/posgrados en pediatría y pediatras de la Sociedad Uruguaya de Pediatría, de Montevideo y el interior del país. La fuente de datos fue una encuesta online anónima. El análisis de datos fueron frecuencias relativas y absolutas para variables cualitativas. Resultados: se enviaron 1.080 encuestas online, de las que se incluyeron 119. Sobre la autopercepción en el conocimiento de los encuestados, el 58,0% se calificó dentro del rango medio. Acerca del concepto de dieta ovolactovegetariana, 63,9% seleccionó la opción correcta. Más de 50,0% respondió correctamente acerca de conocimientos sobre nutrientes en la mayoría de los ítems. Iniciar estas dietas en la alimentación complementaria fue desaconsejado por el 58% de los socios. Un 79,8% pretende adquirir más conocimientos del tema. Conclusiones: más de la mitad de los profesionales tiene los conocimientos correctos acerca de la correcta planificación y suplementación de dietas vegetarianas en niños. Se destaca la necesidad de incluir dietas vegetarianas en las guías de alimentación pediátrica en territorio uruguayo.

Introduction: the number of vegetarian people has increased considerably in recent years. Caution is suggested when incorporating this type of diet to the pediatric population. This diet has not been contemplated in the current national nutritional guidelines, generating uncertainty among pediatricians when making recommendations. Objective: describe the knowledge Pediatric Physicians and graduate / resident members of the Uruguayan Society of Pediatrics have regarding vegetarian diets in children during the period June-September 2020. Determine the need of the participants of the survey to incorporate vegetarian diet information into the Uruguayan Pediatric Nutritional Guidelines. Materials and methods: descriptive observational study, cross-sectional survey carried out from June to September 2020. The inclusion criteria included resident doctors / postgraduate pediatricians and pediatricians from the Uruguayan Society of Pediatrics of Montevideo and the interior of the country. The data source was an anonymous online survey. The data analyses were relative and absolute frequencies of qualitative variables. Results: 1.080 online surveys were sent and 119 were included. Regarding the respondents' self-perception of knowledge, 58.0% were rated within the medium range. Regarding the concept of lacto-ovo-vegetarian diet, 63.9% selected the correct option. Regarding knowledge about nutrients, we obtained more than 50.0% of correct answers in most of the items. Starting these diets as supplementary food was discouraged by 58% of the participants. 79.8% expressed the intention to acquire more knowledge regarding the subject. Conclusions: more than half of the professionals have the correct knowledge about the correct planning and supplementation of vegetarian diets in children. They stressed the need to include vegetarian diets in pediatric food guidelines in Uruguay.

Introdução: nos últimos anos, o aumento das pessoas vegetarianas tem sido considerável. Deve-se ter cuidado ao incorporar esse tipo de dieta na população pediátrica. Ela não está incluída nas atuais diretrizes nacionais de nutrição, gerando incerteza nos pediatras no momento de fazer recomendações. Objetivo: descrever o conhecimento sobre dietas vegetarianas em crianças dos Pediatras e pós-graduados/residentes da Sociedade Uruguaia de Pediatria no período de junho a setembro de 2020 para poder determinar a necessidade de incorporar dietas vegetarianas às diretrizes nutricionais pediátricas uruguaias. Material e métodos: estudo observacional descritivo, tipo de pesquisa transversal realizada no período de junho a setembro de 2020. Os critérios de inclusão foram médicos residentes/pós-graduados em pediatria e pediatras da Sociedade Uruguaia de Pediatria, Montevidéu e interior do país. A fonte de dados foi uma pesquisa on-line anônima sobre a necessidade de incorporar dietas vegetarianas às diretrizes uruguaias para nutrição pediátrica. As análises dos dados foram frequências relativas e absolutas de variáveis qualitativas. Resultados: 1.080 pesquisas online foram enviadas e 119 foram incluídas. Quanto à autopercepção de conhecimento dos entrevistados, 58,0% foram avaliados dentro da faixa média. Quanto ao conceito de dieta lacto-ovo-vegetariana, 63,9% selecionaram a opção correta. Quanto ao conhecimento sobre nutrientes, obtivemos mais de 50,0% das respostas corretas na maioria dos itens. O início dessas dietas como alimentos suplementares foi desencorajado por 58% dos participantes. 79,8% expressaram a intenção de adquirir mais conhecimento sobre o assunto. Conclusões: mais da metade dos profissionais têm o conhecimento correto sobre o planejamento correto e suplementação de dietas vegetarianas em crianças. Eles enfatizaram a necessidade de incluir dietas vegetarianas nas diretrizes de alimentos pediátricos no Uruguai.

Development of a Novel Perfusable Solution for ex vivo Preservation: Towards Photosynthetic Oxygenation for Organ Transplantation.

Oxygen is the key molecule for aerobic metabolism, but no animal cells can produce it, creating an extreme dependency on external supply. In contrast, microalgae are photosynthetic microorganisms, therefore, they are able to produce oxygen as plant cells do. As hypoxia is one of the main issues in organ transplantation, especially during preservation, the main goal of this work was to develop the first generation of perfusable photosynthetic solutions, exploring its feasibility for ex vivo organ preservation. Here, the microalgae Chlamydomonas reinhardtii was incorporated in a standard preservation solution, and key aspects such as alterations in cell size, oxygen production and survival were studied. Osmolarity and rheological features of the photosynthetic solution were comparable to human blood. In terms of functionality, the photosynthetic solution proved to be not harmful and to provide sufficient oxygen to support the metabolic requirement of zebrafish larvae and rat kidney slices. Thereafter, isolated porcine kidneys were perfused, and microalgae reached all renal vasculature, without inducing damage. After perfusion and flushing, no signs of tissue damage were detected, and recovered microalgae survived the process. Altogether, this work proposes the use of photosynthetic microorganisms as vascular oxygen factories to generate and deliver oxygen in isolated organs, representing a novel and promising strategy for organ preservation.