Esphera SynBio is a synthetic biology company with a platform technology allowing for the production of modified exosomes. This is achieved not through the modification of isolated exosomes but rather through the modification or producer cells through the expression of multimeric proteins. As this simply relies on the expression of our transgenes this technology can cause the production of designer exosomes in vitro (from modified cells in a bioreactor) or in vivo (following delivery of our transgenes by various means. Applications include the generation of immunostimulatory, tumour-derived personalized vaccines in situ, the enhancement of standard vaccines and the delivery of specific RNAs to target cells.