Mesoblast(?) Australian Covid-19 Trial Victor Chang Cardiac Research Institute, page-59

Given remestemcel has been approved for the treatment of graft versus host disease in children in Japan, Canada and NZ. I would not expect much in the way of side effects in adults. Growing children are more complex and at at risk organisms than adults. Whereas, hydroxychloroquine is contraindicated (ie prohibited) in children less than 6 years of old, with strong caution in older children. All of us already have stem cells in our body, but we do not have hydroxychloroquine or remdesivir in our blood streams. The main issue would be allergy, but it appears as the stem cells are early progenitor cells they do not express antigens that could trigger an allergic reaction.