title: Erythropoietin in combination of tissue plasminogen activator exacerbates brain hemorrhage when treatment is initiated 6 hours after stroke.
abstract: OBJECTIVE
  Erythropoietin (EPO), a hematopoietic cytokine, exerts neuroprotective effects in experimental stroke. In the present study, we investigated the effect of recombinant human EPO (rhEPO) in combination with tissue plasminogen activator (tPA) on embolic stroke.
  
  
  METHODS
  Rats subjected to embolic middle cerebral artery occlusion (MCAO) were treated with rhEPO (5000 U/kg) in combination with tPA (10 mg/kg) at 2 or 6 hours after MCAO. Control groups consisted of ischemic rats treated with rhEPO (5000 U/kg) alone, tPA (10 mg/kg) alone, or saline at 2 or 6 hours after MCAO.
  
  
  RESULTS
  The combination therapy of rhEPO and tPA initiated 6 hours after MCAO did not reduce the ischemic lesion volume and significantly (P<0.05) increased the incidence of brain hemorrhage measured by frequency of gross hemorrhage and a quantitative spectrophotometric hemoglobin assay compared with rats treated with rhEPO alone and tPA alone. However, when the combination therapy was initiated 2 hours after MCAO, the treatment significantly (P<0.05) reduced the lesion volume and did not substantially increase the incidence of hemorrhagic transformation compared with saline-treated rats. Immunostaining analysis revealed that the combination therapy of rhEPO and tPA at 6 hours significantly (P<0.05) increased matrix metalloproteinase-9, NF-kappaB, and interleukin-1 receptor-associated kinase-1 immunoreactive cerebral vessels compared with rats treated with rhEPO alone and saline.
  
  
  CONCLUSIONS
  EPO exacerbates tPA-induced brain hemorrhage without reduction of ischemic brain damage when administered 6 hours after stroke in a rat model of embolic MCAO and that matrix metalloproteinase-9, NF-kappaB, and interleukin-1 receptor-associated kinase-1 upregulated by the delayed combination therapy may contribute to augmentation of brain hemorrhage.
authors.affiliation: Department of Neurology, Henry Ford Hospital, Detroit, Mich 48202, USA.
authors.forename: Longfei
authors.initials: L
authors.lastname: Jia
authors.forename: Michael
authors.initials: M
authors.lastname: Chopp
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Mei
authors.initials: M
authors.lastname: Lu
authors.forename: Zhenggang
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D016009:Chi-Square Distribution; D004359:Drug Therapy, Combination / Q000009:adverse effects; D004921:Erythropoietin / Q000009:adverse effects*; D007150:Immunohistochemistry; D053592:Interleukin-1 Receptor-Associated Kinases / Q000378:metabolism; D020300:Intracranial Hemorrhages / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020521:Stroke / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D013997:Time Factors; D010959:Tissue Plasminogen Activator / Q000009:adverse effects*; D016896:Treatment Outcome
chemical_list: D016328:NF-kappa B; D004921:Erythropoietin; C547807:IRAK1 protein, rat; D053592:Interleukin-1 Receptor-Associated Kinases; D010959:Tissue Plasminogen Activator; D020780:Matrix Metalloproteinase 9