mTOR inhibition and erythropoiesis: microcytosis or anaemia?

Background. Anaemia and microcytosis are common post kidney transplantation. The aim of this study was to evaluate the potential role of mammalian target of rapamycin (mTOR) inhibition in the development of anaemia and microcytosis in healthy animals and in human erythroid cultures in vitro. Methods. Rats with normal kidney function were treated with sirolimus (n ¼ 7) or vehicle (n ¼ 8) for 15 weeks. Hemograms were determined thereafter. In the sirolimus withdrawal part of the study, rats received sirolimus (SRL) for 67 days (n ¼ 4) 1 mg/kg three times per week or for 30 days (n ¼ 4) and were observed until Day 120. Hemograms were performed regularly. Peripheral blood mononuclear cells from healthy controls (HC; n ¼ 8), kidney transplant patients with sirolimus treatment with (SRL 1 MC; n ¼ 8) or without microcytosis