It is also imperative that the clinical investigations be conducted in a transparent manner according to established precedents for clinical investigations of potential new therapies for critical illnesses [53]. This includes recognised end-points, including but not limited to overall mortality, length of ICU and hospital stay and ventilator-free days. We also strongly advocate for utilising clinical samples, obtained as part of appropriate clinical care or for monitoring adverse events following cell administration, to obtain mechanistic information including but not limited to analyses of circulating pro- and anti-inflammatory mediators and inflammatory cell populations. Given the rapidity of the COVID-19 spread and the increasing numbers of cell-based therapy investigations, a central coordinating centre to expedite congruent trial design and appropriate data dissemination would be of significant benefit.