Comparison of neuroprotective effects of erythropoietin (EPO) and carbamylerythropoietin (CEPO) against ischemia-like oxygen–glucose deprivation (OGD) and NMDA excitotoxicity in mouse hippocampal slice cultures

Abstract

In addition to its well-known hematopoietic effects, erythropoietin (EPO) also has neuroprotective properties. However, hematopoietic side effects are unwanted for neuroprotection, underlining the need for EPO-like compounds with selective neuroprotective actions. One such compound, devoid of hematopoietic bioactivity, is the chemically modified, EPO-derivative carbamylerythropoietin (CEPO). For comparison of the neuroprotective effects of CEPO and EPO, we subjected organotypic hippocampal slice cultures to oxygen-glucose deprivation (OGD) or N-methyl-D-aspartate (NMDA) excitotoxicity. Hippocampal slice cultures were pretreated for 24 h with 100 IU/ml EPO (= 26 nM) or 26 nM CEPO before OGD or NMDA lesioning. Exposure to EPO and CEPO continued during OGD and for the next 24 h until histology, as well as during the 24 h exposure to NMDA. Neuronal cell death was quantified by cellular uptake of propidium iodide (PI), recorded before the start of OGD and NMDA exposure and 24 h after. In cultures exposed to OGD or NMDA, CEPO reduced PI uptake by 49 ± 3 or 35 ± 8%, respectively, compared to lesion-only controls. EPO reduced PI uptake by 33 ± 5 and 15 ± 8%, respectively, in the OGD and NMDA exposed cultures. To elucidate a possible mechanism involved in EPO and CEPO neuroprotection against OGD, the integrity of α-II-spectrin cytoskeletal protein was studied. Both EPO and CEPO significantly reduced formation of spectrin cleavage products in the OGD model. We conclude that CEPO is at least as efficient neuroprotectant as EPO when excitotoxicity is modeled in mouse hippocampal slice cultures.

Erythropoietin and Oxidative Stress

“…In cells that involve the brain or the retina, EPO can prevent injury from hypoxic ischemia , Chong, et al, 2002b, Liu, et al, 2006, Meloni, et al, 2006, Wei, et al, 2006, Yu, et al, 2005, excitotoxicity (Montero, et al, 2007, Yamasaki, et al, 2005, infection (Kaiser, et al, 2006), free radical exposure , Chong, et al., 2003e, Yamasaki, et al, 2005, staurosporine (Pregi, et al, 2006), and dopaminergic cell injury (Demers, et al, 2005, McLeod, et al, 2006. In addition, administration of EPO also represents a viable option for the prevention of retinal cell injury during glaucoma (Tsai, et al, 2007).…”

“…The passage of EPO entry into the central nervous system continues to attract significant interest (Doolittle, et al, 2007) as well as does the use of novel intranasal routes for EPO administration (Yu, et al, 2005). Other avenues of study are directed to the development of derivations of EPO to reduce erythropoietic activity and the potential associated vascular complications (Montero, et al, 2007). Yet, these lines of investigation are not without limitations, since chemical derivatives of EPO can become absent of clinical efficacy as well as possibly loose the ability to promote sustainable cytoprotective effects, such as neurogenesis (Gonzalez, et al, 2007) and angiogenesis , Reinders, et al, 2006, Slevin, et al, 2006, Zhang and Ma, 2007.…”

The Receptor That Tames the Innate Immune Response

“…A number of such compounds have been designed and validated. Modification of the EPO protein (for example, CEPO [33] or S100E EPO [61]) or peptides on the basis of the three-dimensional structure of EPO (62) results in tissue-protective molecules as potent as EPO but devoid of erythropoietic and hematopoietic activities.…”

Investigation of the protective effect of erythropoietin on spinal cord injury in rats

“…EPO exhibits neuroprotective effects in a variety of models of central and peripheral nervous system injury (9,10). The local EPO and EPO-R system is markedly engaged in the early stages after compressive spinal cord injury.…”