The invention concerns a method for lyophilising exosomes by providing an exosome suspension in a lyophilisation buffer comprising a sugar at less than 10% w/v. The method is to preserve exosomes structural and biochemical integrity as well as the therapeutic efficacy for long term storage at ambient temperature. In one embodiment, the lyophilisation buffer comprises trehalose at 4% w/v. In another embodiment, removal of water from the frozen suspension deposits the exosomes on a biocompatible scaffold.
