Four of the trials will utilise either MSC-derived conditioned media or extracellular vesicles. Two of these propose aerosol inhalation of MSC-derived extracellular vesicles, one from AD-MSCs, for which there is no pre-clinical supporting data. Six investigations will utilise other cells, including umbilical cord blood-derived mononuclear cells, cytotoxic T-cells, dendritic cells, NK cells, cord blood stem cells and cytokine-induced killer cells, of which only the latter investigation describes dosing and frequency of injections. As best as we can ascertain, there are no apparent pre-clinical data to support the rationale for any of these approaches.