Anti-fibrotic mechanisms of exogenously-expanded mesenchymal stromal cells for fibrotic diseases

•MSCs modulate fibrosis via chemokines/cytokines and extracellular vesicles.•There exists a large degree of efficacy variability in pre-clinical MSC studies.•MSCs can be modified to potentially improve pre-clinical and clinical outcomes.•Clinically, MSCs are safe but efficacy has not been adequately demonstrated.•Reducing variability in pre- and clinical studies is necessary moving forward.