Exosomes, nano-sized vesicles secreted by cells, have attracted increasing interest in biomedical research due to their unique properties, including biocompatibility, content-loading capacity, and deep tissue penetration. point on their potential, what they are and where and when to use them (*).
Essential for intercellular communication, exosomes are a nanometric subset (30-200nm) of extracellular vesicles released by cells ( Figure 1 ) as part of their normal physiology or in certain pathologies. They serve as natural signaling agents in intercellular communication, and contain amino acids, lipids, growth factors, peptides, minerals, vitamins, which gives them remarkable therapeutic potential, particularly for chemotherapy, gene therapy and photothermal therapy.
Figure 1: Classification of extracellular vesicles, biogenesis and structure of exosomes (1).
Several sources of exosomes are available today: human, animal or plant, natural or engineered with cells originating from macrophages, dendritic cells, tumor cells, platelets, mesenchymal or neural stem cells… ( Figure 2 )(2). If exosomes are the miniature version of the cells from which they come, their content can however be modified, but they cannot replicate because they do not contain a nucleus. However, they are stable in biological fluids with high biocompatibility, have a long half-life and protect their content from any degradation (3). Well tolerated and with very low immunogenicity, they can have immunomodulatory, anti-inflammatory, antioxidant, anti-apoptotic, angiogenic and tissue repair properties, which underlines their interest (3). It is therefore not surprising that exosomes from mesenchymal stem cells have been successfully tested in many age-related or inflammatory pathologies: Covid-19, ARDS, COPD, bronchopulmonary dysplasia, Alzheimer's or Parkinson's disease, refractory epilepsy, Crohn's disease, ulcerative colitis, etc. (4), or in dermatology in psoriasis, atopic dermatitis or skin rejuvenation (5). This benefit seems to be linked to the angiogenic capacities of exosomes, to the fact that they promote collagen synthesis and regulate inflammation. Several methods of administration have been tested in anti-aging dermatology, reports Beatrice Devos: by micro-needles, by subdermal injections, by fractional CO2 laser or by injection into the wound to minimize scars. Whatever the benefits of these treatments, and although it is a safer and less versatile technique than stem cell treatment, it should be noted that treatment with exosomes of human origin is not authorized in the European Union, which is possible, under certain conditions, in the United States.
Figure 2: a) production and purification of exosomes; b) content of natural exosomes; c) modification of exosomes (2).
(BM bone marrow, DC dendritic cell, IAC immunoaffinity chromatography, iPSC induced pluripotent stem cell, MHC major histocompatibility complex, miRNA microRNA, MSC mesenchymal stem cell, MVB multivesicular body, NSC neural stem cell, SEC size-exclusion chromatography, UC umbilical cord)
(*) Based on a presentation by Dr Beatrice Devos (Antwerp), at the last congress of the Belgian Society of Aesthetic Medicine
