Exploração do Potencial Terapêutico do Secretoma Derivado de Macrófagos para a Regeneração de Lesões Vertebro-Medulares

During development the human embryo orchestrates the creation of all our organs, from simple forms to complex and intricate structures such as the central nervous system. However, when tragedy strikes in the form of a SCI, there is a need to repair this sophisticate network of cells. Recreating human development is no longer possible because the environment changed. However, there are new actors that can play a key role in the remake of a new and functional spinal cord. This project introduces a novel cast to the SCI stage: the regenerative macrophages M2c. There are several limitations regarding cell transplantation in a SCI clinical context. These include the substantial quantity of cells required, the low rates of cell survival upon transplantation, and most important, the influence of the tissue microenvironment on the phenotype of macrophages [6]. Recognizing these limitations, I propose a paradigm shift by opting for the use of secretome and EVs from these macrophage populations. With REGEN4SCI, the main goal is to modulate the hostile neuro-inflammatory environment, thereby fostering a local milieu conducive to regeneration and functional recovery. The outcomes of our project hold the potential for impactful results, offering significant advantages to individuals with SCI. THE HYPOTHESIS & WORKING MODEL Using the proteins and extracellular vesicles produced by pro-regenerative macrophages it will be possible to modulate the aggressive neuro-inflammatory environment seen after SCI, contributing to generate a local environment that fosters tissue repair and leads to functional recovery. While our previous data demonstrate the therapeutic potential of M2c-secreted molecules, they fall short in revealing the comprehensive contributions of dosage, route and timing of administration, to the spinal cord regeneration process. Consequently, our focus lies in establishing a novel therapeutic approach that intricately considers the nuanced roles of these clinical relevant issues. REGEN4SCI involves utilizing the proteins and extracellular vesicles derived from M2c regenerative macrophages, delivering them within the optimal time window. The absence of such an immunomodulatory approach presents an obvious disadvantage, as it fails to comprehensively address key facets of the regenerative immune response. With this project, strong outputs may be achieved, with potential advantages to individuals with SCI. In order to achieve the main goal, REGEN4SCI project has the following sub aims (Fig. 3): 1) Determine the most effective dose. In our previous results we exclusively examined a single concentration (secretome 1x, 3μg/ml). Therefore, it is imperative to ascertain whether higher doses exhibit increased efficacy without inducing harmful effects. In this sense, we aim to establish the dose-response curve for REGEN4SCI therapy. The secretome will be concentrated 2, 5 and 10 times and its therapeutic effect will be analysed using a thoracic compression injury model. A thorough evaluation will be performed, including: motor, sensory, autonomic and histological recovery as well as toxicity analysis. 2) Determine the most effective route of administration. Our previous findings indicate that M2c secretome leads to functional recovery when delivered by i.p. injection, however, it remains unknown whether intrathecal injections offer superior efficacy compared to systemic administration. Using the same thoracic compression injury model and the s