EPO and stroke disorder: In parallel, the present study shows that treatment with rhEPO did not prevent loss of mature oligodendrocytes but significantly increased the number of OPCs 7 days after stroke, while treatment with rhEPO substantially increased myelinating oligodendrocytes at the ischemic boundary 28 and 42 days after stroke, indicating that EPO likely acts on oligodendrogenesis rather than on protecting oligodendrocytes.