Cytoprotective doses of erythropoietin or carbamylated erythropoietin have markedly different procoagulant and vasoactive activities.
Recombinant human erythropoietin (rhEPO) is receiving increasing attention as a potential therapy for prevention of injury and restoration of function in nonhematopoietic tissues. However, the minimum effective dose required to mimic and augment these normal paracrine functions of erythropoietin (EPO) in some organs (e.g., the brain) is higher than for treatment of anemia. Notably, a dose-dependent risk of adverse effects has been associated with rhEPO administration, especially in high-risk groups, including polycythemia-hyperviscosity syndrome, hypertension, and vascular thrombosis. Of note, several clinical trials employing relatively high dosages of rhEPO in oncology patients were recently halted after an increase in mortality and morbidity, primarily because of thrombotic events. We recently identified a heteromeric EPO receptor complex that mediates tissue protection and is distinct from the homodimeric receptor responsible for the support of erythropoiesis. Moreover, we developed receptor-selective ligands that provide tools to assess which receptor isoform mediates which biological consequence of rhEPO therapy. Here, we demonstrate that rhEPO administration in the rat increases systemic blood pressure, reduces regional renal blood flow, and increases platelet counts and procoagulant activities. In contrast, carbamylated rhEPO, a heteromeric receptor-specific ligand that is fully tissue protective, increases renal blood flow, promotes sodium excretion, reduces injury-induced elevation in procoagulant activity, and does not effect platelet production. These preclinical findings suggest that nonerythropoietic tissue-protective ligands, which appear to elicit fewer adverse effects, may be especially useful in clinical settings for tissue protection.
The Kenneth S. Warren Institute, Warren Pharmaceuticals, Ossining, NY 10562, USA. tcoleman@kswi.org
Thomas R
TR
Coleman
Christof
C
Westenfelder
Florian E
FE
Tögel
Ying
Y
Yang
Zhuma
Z
Hu
Leanne
L
Swenson
Henri G D
HG
Leuvenink
Rutger J
RJ
Ploeg
Livius V
LV
d'Uscio
Zvonimir S
ZS
Katusic
Pietro
P
Ghezzi
Adriana
A
Zanetti
Kenneth
K
Kaushansky
Norma E
NE
Fox
Anthony
A
Cerami
Michael
M
Brines
D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D003029:Coagulants / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D004921:Erythropoietin / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use; D006410:Hematopoiesis / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D051379:Mice; D012079:Renal Circulation / Q000187:drug effects / Q000502:physiology; D013234:Stem Cells / Q000187:drug effects / Q000502:physiology; D014471:Umbilical Veins
D003029:Coagulants; C488171:carbamylated erythropoietin; D004921:Erythropoietin