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1.
Am J Physiol Renal Physiol ; 315(2): F364-F373, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29693449

RESUMO

Animal models of chronic kidney disease (CKD) are critical for understanding its pathophysiology and for therapeutic development. The cardiovascular and renal anatomy and physiology of the pig are virtually identical to humans. This study aimed to develop a novel translational model of CKD that mimics the pathological features of CKD in humans. CKD was induced in seven domestic pigs by bilateral renal artery stenosis and diet-induced dyslipidemia. Animals were observed for a total of 14 wk. Renal hemodynamics and function were quantified in vivo using multi-detector CT after 6, 10, and 14 wk of CKD. Urine and blood were collected at each time-point, and blood pressure was continuously measured (telemetry). After completion of in vivo studies, pigs were euthanized, kidneys were removed, and microvascular (MV) architecture (µCT), markers of renal injury, inflammation, and fibrosis were evaluated ex vivo. Additional pigs were used as controls ( n = 7). Renal blood flow and glomerular filtration were reduced by 50% in CKD, accompanied by hypertension and elevated plasma creatinine, albumin-to-creatinine ratio and increased urinary KIM-1 and NGAL, suggesting renal injury. Furthermore, 14 wk of CKD resulted in cortical and medullary MV remodeling and loss, inflammation, glomerulosclerosis, tubular atrophy, and tubule-interstitial fibrosis compared with controls. The current study characterizes a novel model of CKD that mimics several of the pathological features observed in human CKD, irrespective of the etiology. Current approaches only slow rather than halt CKD progression, and this novel model may offer a suitable platform for the development of new treatments in a translational fashion.


Assuntos
Rim , Insuficiência Renal Crônica , Pesquisa Translacional Biomédica/métodos , Animais , Biomarcadores/sangue , Biomarcadores/urina , Dieta Hiperlipídica , Modelos Animais de Doenças , Progressão da Doença , Dislipidemias/complicações , Feminino , Taxa de Filtração Glomerular , Hemodinâmica , Humanos , Rim/irrigação sanguínea , Rim/metabolismo , Rim/patologia , Obstrução da Artéria Renal/complicações , Circulação Renal , Insuficiência Renal Crônica/etiologia , Insuficiência Renal Crônica/metabolismo , Insuficiência Renal Crônica/patologia , Insuficiência Renal Crônica/fisiopatologia , Especificidade da Espécie , Sus scrofa , Fatores de Tempo
2.
Kidney Int ; 93(4): 842-854, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29273331

RESUMO

We recently developed a therapeutic biopolymer composed of an elastin-like polypeptide (ELP) fused to vascular endothelial growth factor (VEGF) and showed long-term renoprotective effects in experimental renovascular disease after a single intra-renal administration. Here, we sought to determine the specificity, safety, efficacy, and mechanisms of renoprotection of ELP-VEGF after systemic therapy in renovascular disease. We tested whether kidney selectivity of the ELP carrier would reduce off-target binding of VEGF in other organs. In vivo bio-distribution after systemic administration of ELP-VEGF in swine was determined in kidneys, liver, spleen, and heart. Stenotic-kidney renal blood flow and glomerular filtration rate were quantified in vivo using multi-detector computed tomography (CT) after six weeks of renovascular disease, then treated with a single intravenous dose of ELP-VEGF or placebo and observed for four weeks. CT studies were then repeated and the pigs euthanized. Ex vivo studies quantified renal microvascular density (micro-CT) and fibrosis. Kidneys, liver, spleen, and heart were excised to quantify the expression of angiogenic mediators and markers of progenitor cells. ELP-VEGF accumulated predominantly in the kidney and stimulated renal blood flow, glomerular filtration rate, improved cortical microvascular density, and renal fibrosis, and was accompanied by enhanced renal expression of VEGF, downstream mediators of VEGF signaling, and markers of progenitor cells compared to placebo. Expression of angiogenic factors in liver, spleen, and heart were not different compared to placebo-control. Thus, ELP efficiently directs VEGF to the kidney after systemic administration and induces long-term renoprotection without off-target effects, supporting the feasibility and safety of renal therapeutic angiogenesis via systemic administration of a novel kidney-specific bioengineered compound.


Assuntos
Indutores da Angiogênese/farmacologia , Rim/irrigação sanguínea , Rim/efeitos dos fármacos , Neovascularização Fisiológica/efeitos dos fármacos , Peptídeos/farmacologia , Obstrução da Artéria Renal/tratamento farmacológico , Fator A de Crescimento do Endotélio Vascular/farmacologia , Indutores da Angiogênese/administração & dosagem , Indutores da Angiogênese/farmacocinética , Indutores da Angiogênese/toxicidade , Animais , Apoptose/efeitos dos fármacos , Biomarcadores/metabolismo , Modelos Animais de Doenças , Portadores de Fármacos , Fibrose , Taxa de Filtração Glomerular/efeitos dos fármacos , Injeções Intravenosas , Rim/metabolismo , Rim/patologia , Peptídeos/administração & dosagem , Peptídeos/farmacocinética , Peptídeos/toxicidade , Proteínas Recombinantes de Fusão/farmacologia , Obstrução da Artéria Renal/metabolismo , Obstrução da Artéria Renal/patologia , Obstrução da Artéria Renal/fisiopatologia , Circulação Renal/efeitos dos fármacos , Células-Tronco/efeitos dos fármacos , Células-Tronco/metabolismo , Sus scrofa , Distribuição Tecidual , Fator A de Crescimento do Endotélio Vascular/administração & dosagem , Fator A de Crescimento do Endotélio Vascular/farmacocinética , Fator A de Crescimento do Endotélio Vascular/toxicidade
3.
Am J Nephrol ; 43(2): 74-84, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26930122

RESUMO

BACKGROUND: Podocytes are major components of the filtration barrier and a renal source of vascular endothelial growth factor (VEGF). Chronic renovascular disease (RVD) progressively degrades the renal function, accompanied by podocyte damage and a progressive reduction in VEGF. We showed that the endothelin (ET) pathway contributes to this pathological process and ET-A (but not ET-B) receptor antagonism protects the kidney in RVD. We hypothesize that ET-A-induced renoprotection is largely driven by the protection of podocyte integrity and function. METHODS: To mimic the renal environment of chronic RVD, human podocytes were incubated under chronic hypoxia for 96 h and divided in untreated or treated with an ET-A or ET-B receptor antagonist. Cells were quantified after 96 h. Cell homogenates and media were obtained after 1, 24 and 96 h to quantify production of VEGF, anti-VEGF soluble receptor s-Flt1, and the expression of apoptotic mediators. A separate set of similar experiments was performed after addition of a VEGF-neutralizing antibody (VEGF-NA). RESULTS: Hypoxia decreased podocyte number, which was exacerbated by ET-B but improved after ET-A antagonism. Production of VEGF was preserved by ET-A antagonism, whereas s-Flt1 increased in hypoxic cells after ET-B antagonism only, accompanied by a greater expression of pro-apoptotic mediators. On the other hand, treatment with VEGF-NA diminished ET-A-induced protection of podocytes. CONCLUSION: ET-A antagonism preserves podocyte viability and integrity under chronic hypoxia, whereas ET-B antagonism exacerbates podocyte dysfunction and death. Enhanced bioavailability of VEGF after ET-A antagonism could be a pivotal mechanism of podocyte protection that significantly contributes to ET-A receptor blockade-induced renal recovery in chronic RVD.


Assuntos
Anticorpos Neutralizantes/farmacologia , Hipóxia Celular/efeitos dos fármacos , Antagonistas do Receptor de Endotelina A/farmacologia , Antagonistas do Receptor de Endotelina B/farmacologia , Fator A de Crescimento do Endotélio Vascular/metabolismo , Fator A de Crescimento do Endotélio Vascular/farmacologia , Apoptose/efeitos dos fármacos , Contagem de Células , Hipóxia Celular/fisiologia , Sobrevivência Celular/efeitos dos fármacos , Endotelina-1/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/metabolismo , Podócitos , Fatores de Proteção , Receptor de Endotelina A/metabolismo , Receptor de Endotelina B/metabolismo , Fator A de Crescimento do Endotélio Vascular/imunologia , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/metabolismo
4.
J Am Soc Nephrol ; 27(6): 1741-52, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26541349

RESUMO

Renovascular disease (RVD) induces renal microvascular (MV) rarefaction that drives progressive kidney injury. In previous studies, we showed that renal vascular endothelial growth factor (VEGF) therapy attenuated MV damage, but did not resolve renal injury at practical clinical doses. To increase the bioavailability of VEGF, we developed a biopolymer-stabilized elastin-like polypeptide (ELP)-VEGF fusion protein and determined its in vivo potential for therapeutic renal angiogenesis in RVD using an established swine model of chronic RVD. We measured single-kidney blood flow (RBF) and GFR and established the degree of renal damage after 6 weeks of RVD. Pigs then received a single stenotic kidney infusion of ELP-VEGF (100 µg/kg), a matching concentration of unconjugated VEGF (18.65 µg/kg), ELP alone (100 µg/kg), or placebo. Analysis of organ distribution showed high renal binding of ELP-VEGF 4 hours after stenotic kidney infusion. Therapeutic efficacy was determined 4 weeks after infusion. ELP-VEGF therapy improved renal protein expression attenuated in RVD, restoring expression levels of VEGF, VEGF receptor Flk-1, and downstream angiogenic mediators, including phosphorylated Akt and angiopoietin-1 and -2. This effect was accompanied by restored MV density, attenuated fibrogenic activity, and improvements in RBF and GFR greater than those observed with placebo, ELP alone, or unconjugated VEGF. In summary, we demonstrated the feasibility of a novel therapy to curtail renal injury. Recovery of the stenotic kidney in RVD after ELP-VEGF therapy may be driven by restoration of renal angiogenic signaling and attenuated fibrogenic activity, which ameliorates MV rarefaction and improves renal function.


Assuntos
Rim/irrigação sanguínea , Neovascularização Fisiológica , Obstrução da Artéria Renal/tratamento farmacológico , Fator A de Crescimento do Endotélio Vascular/uso terapêutico , Animais , Bioengenharia , Elastina , Humanos , Peptídeos , Polímeros , Suínos
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