RESUMO
Deep second-degree burns are characterized by delayed formation of granulation tissue and impaired angiogenesis. Erythropoietin (EPO) is able to stimulate angiogenesis and mitosis, activating vascularization and cell cycle. The aim of our study was to investigate whether two biosimilar recombinant human erythropoietins, EPO-α and EPO-Z, may promote these processes in an experimental model of burn injury. A total of 84 mice were used and a scald burn was produced on the back after shaving, in 80°C water for 10 seconds. Mice were then randomized to receive EPO-α (400 units/kg/day/sc) or EPO-Z (400 units/kg/day/sc) or their vehicle (100 µL/day/sc 0.9% NaCl solution). After 12 days, both EPO-α and EPO-Z increased VEGF protein expression. EPO-α caused an increased cyclin D1/CDK6 and cyclin E/CDK2 expression compared with vehicle and EPO-Z (p<0.001). Our study showed that EPO-α and EPO-Z accelerated wound closure and angiogenesis; however EPO-α resulted more effectively in achieving complete skin regeneration. Our data suggest that EPO-α and EPO-Z are not biosimilars for the wound healing effects. The higher efficacy of EPO-α might be likely due to its different conformational structure leading to a more efficient cell proliferation and skin remodelling.
Assuntos
Lesões Encefálicas/tratamento farmacológico , Epoetina alfa/administração & dosagem , Eritropoetina/administração & dosagem , Neovascularização Fisiológica/genética , Proteínas Recombinantes/administração & dosagem , Animais , Lesões Encefálicas/genética , Queimaduras/tratamento farmacológico , Queimaduras/fisiopatologia , Epoetina alfa/genética , Eritropoetina/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Camundongos , Modelos Teóricos , Neovascularização Fisiológica/efeitos dos fármacos , Proteínas Recombinantes/genética , Fator A de Crescimento do Endotélio Vascular/biossíntese , Fator A de Crescimento do Endotélio Vascular/genética , Cicatrização/efeitos dos fármacos , Cicatrização/genéticaRESUMO
KEY MESSAGE: C -terminally fused Strep -tag II is removed from rhuEPO expressed in tobacco plants. The finding suggests that direct fusion of purification tags at the C -terminus of rhuEPO should be avoided. Asialo-erythropoietin (asialo-EPO), a desialylated form of EPO, is a potent tissue-protective agent. Recently, we and others have exploited a low-cost plant-based expression system to produce recombinant human asialo-EPO (asialo-rhuEPO(P)). To facilitate purification from plant extracts, Strep-tag II was engineered at the C-terminus of EPO. Although asialo-rhuEPO(P) was efficiently expressed in transgenic tobacco plants, affinity purification based on Strep -tag II did not result in the recovery of the protein. In this study, we investigated the stability of Strep-tag II tagged asialo-rhuEPO(P) expressed in tobacco plants to understand whether this fused tag is cleaved or inaccessible. Sequencing RT-PCR products confirmed that fused DNA sequences encoding Strep-tag II were properly transcribed, and three-dimensional protein structure model revealed that the tag must be fully accessible. However, Western blot analysis of leaf extracts and purified asialo-rhuEPO(P) revealed that the Strep-tag II was absent on the protein. Additionally, no peptide fragment containing Strep-tag II was identified in the LC-MS/MS analysis of purified protein further supporting that the affinity tag was absent on asialo-rhuEPO(P). However, Strep-tag II was detected on asialo-rhuEPO(P) that was retained in the endoplasmic reticulum, suggesting that the Strep-tag II is removed during protein secretion or extraction. These findings together with recent reports that C-terminally fused Strep-tag II or IgG Fc domain are also removed from EPO in tobacco plants, suggest that its C-terminus may be highly susceptible to proteolysis in tobacco plants. Therefore, direct fusion of purification tags at the C-terminus of EPO should be avoided while expressing it in tobacco plants.
