Recombinant human erythropoietin

Erythropoietin promotes M2 macrophage phagocytosis of Schwann cells in peripheral nerve injury

Following acute sciatic nerve crush injury (SNCI), inflammation and the improper phagocytic clearance of dying Schwann cells (SCs) has effects on remodeling that lead to morbidity and incomplete functional recovery. Therapeutic strategies like the use of erythropoietin (EPO) for peripheral nerve trauma may serve to bring immune cell phagocytotic clearance under control to support debris clearance. We evaluated EPO’s effect on SNCI and found EPO treatment increased myelination and sciatic functional index (SFI) and bolstered anti-apoptosis and phagocytosis of myelin debris via CD206⁺ macrophages when compared to saline treatment. EPO enhanced M2 phenotype activity, both in bone marrow-derived macrophages (BMMØs) and peritoneal-derived macrophages (PMØs) in vitro, as well as in PMØs in vivo. EPO increased efferocytosis of apoptotic sciatic nerve derived Schwann cells (SNSCs) in both settings as demonstrated using immunofluorescence (IF) and flow cytometry. EPO treatment significantly attenuated pro-inflammatory genes (IL1β, iNOS, and CD68) and augmented anti-inflammatory genes (IL10 and CD163) and the cell-surface marker CD206. EPO also increased anti-apoptotic (Annexin V/7AAD) effects after lipopolysaccharide (LPS) induction in macrophages. Our data demonstrate EPO promotes the M2 phenotype macrophages to ameliorate apoptosis and efferocytosis of dying SCs and myelin debris and improves SN functional recovery following SNCI.

Drugs acting on blood and/or blood forming organs

Pharmacologic therapy for anemia is oriented toward (1) providing components needed for red blood cell production (vitamin B12 and folic acid), including hemoglobin synthesis (iron and other minerals), and (2) stimulating bone marrow formation of red blood cells. Drugs used to stimulate bone marrow activity will be the focus of this article.

The use of erythropoietin in renal failure

The treatment of renal anaemia by recombinant human erythropoietin (EPO) is now well established. Several studies have examined the pharmacokinetics and efficacy of the drug given intravenously, intraperitoneally and subcutaneously and there is increasing evidence that the subcutaneous route has several advantages including the requirement for a lower dose. It is also important to stress the need for careful determination of baseline iron status of all patients before commencing EPO therapy. In the long term the extremely high iron stores of transfusion dependent patients will disappear. In the short term, however, the majority of the patients whose serum ferritin is less than 100 micrograms/l will require iron supplementation to allow an appropriate haemoglobin response. Alternatively, a fall in transferrin saturation to less than 20% is certainly an indication for iron supplementation and if oral iron therapy is not adequate then intravenous preparations may have to be considered. Although the anaemia of renal failure can be fully corrected by EPO, partial correction may be sufficient to reverse the problems of reduced exercise capacity, myocardial ischaemia and cardiomegaly which are frequently associated with end-stage renal disease. Partial correction will also result in a lesser rise in whole blood viscosity and, in turn, possibly reduce hypertension, thrombosis and increased peripheral resistance and thus lessen the side effects of EPO therapy.