Alternatively activated macrophages as therapeutic agents for kidney disease: in vivo stability is a key factor.

Infusing ex vivo-generated alternatively activated macrophages (AAM) has shown promise in experimental systems as a therapeutic strategy for inflammatory kidney disease. In the mouse Adriamycin nephropathy model, however, Cao et al. report that AAM derived from bone marrow precursors fail to ameliorate disease severity. Absence of the anticipated protective effect resulted from a loss of macrophage anti-inflammatory (M2) phenotype following trafficking to injured kidney-an effect that was mediated by localized colony-stimulating factor-1-dependent macrophage proliferation.