Using a different approach, it has been demonstrated that adoptive transfer of cultured splenic macrophages polarized into M2a or M2c phenotypes can suppress both inflammation and fibrosis in experimental adriamycin-induced nephropathy, with M2c cells showing greater potency owing to their ability to induce the production of immune-suppressing regulatory T cells. In addition, donor-derived regulatory macrophages are being developed as a prophylactic approach to induce tolerance in recipients of kidney and other solid organ transplants,