By presenting a sustained, high concentration of a cytokine, such as IFN‐γ, through incorporation of microparticles within MSC aggregates, the use of MSCs for in vivo immunomodulatory applications could be greatly expanded; for example, MSCs could potentially be transplanted concurrently with graft tissue to effectively suppress an immune response prior to the development of GvHD and severe inflammation. Here, IFNG is linked to graft versus host disease.