To assess the role of the local host environment on activating or altering MSC function and phenotype, we performed a short in vivo study in which mice with acute lung injury (virus or bacteria) were treated with cultured MSCs. After 2,5 hours, the animals will be sacrificed and MSCs were isolated from the lungs. MSCs were sorted and further characterised using single-cell RNA sequencing. Our hypothesis is that different inflammatory environments will induce different immuno-phenotypes of MSCs.