Resumo Fundamento: A doença cardiovascular é a principal causa de morte em todo o mundo. A apoptose mediada por hipóxia em cardiomiócitos é uma das principais causas de distúrbios cardiovasculares. O tratamento com a proteína do fator de crescimento endotelial vascular (VEGF, do inglês vascular endothelial growth factor) foi testado, mas as dificuldades operacionais limitaram seu uso. Entretanto, com os avanços da terapia gênica, aumentou o interesse na terapia gênica baseada no VEGF em doenças cardiovasculares. No entanto, o mecanismo preciso pelo qual a reposição de VEGF resgata os danos pós-hipóxia em cardiomiócitos não é conhecido. Objetivos: Investigar o efeito da expressão de VEGF121 pós-hipóxia utilizando cardiomiócitos de ratos neonatos. Métodos: Cardiomiócitos isolados de ratos neonatos foram utilizados para estabelecer um modelo in vitro de lesão cardíaca induzida por hipóxia. O efeito da superexpressão de VEGF, isolado ou em conjunto com inibidores de moléculas pequenas que têm como alvo os canais de cálcio, receptores sensíveis ao cálcio (CaSR, do inglês calcium-sensitive receptors) e calpaína, no crescimento e proliferação celular em lesão de cardiomiócitos induzidos por hipóxia, foram determinados com ensaio de MTT, coloração TUNEL, coloração com Anexina V/PI, lactato desidrogenase e atividade da caspase. Para análise estatística, um valor de p<0,05 foi considerado significativo. Resultados: Verificou-se que o efeito do VEGF121 foi mediado por CaSR e calpaína, mas não foi dependente dos canais de cálcio. Conclusões: Nossos resultados, mesmo em um ambiente in vitro, estabelecem as bases para uma validação futura e testes pré-clínicos da terapia gênica baseada em VEGF em doenças cardiovasculares.

Abstract Background: Cardiovascular disease is the major cause of death worldwide. Hypoxia-mediated apoptosis in cardiomyocytes is a major cause of cardiovascular disorders. Treatment with vascular endothelial growth factor (VEGF) protein has been tested but operational difficulties have limited its use. However, with the advancements of gene therapy, interest has risen in VEGF-based gene therapy in cardiovascular disorders. However, the precise mechanism by which VEGF replenishment rescues post-hypoxia damage in cardiomyocytes is not known. Objectives: To investigate the effect of post-hypoxia VEGF121 expression using neonatal rat cardiomyocytes. Methods: Cardiomyocytes isolated from neonatal rats were used to establish an in vitro model of hypoxia-induced cardiac injury. The effect of VEGF overexpression, alone or in combination with small-molecule inhibitors targeting calcium channel, calcium sensitive receptors (CaSR), and calpain on cell growth and proliferation on hypoxia-induced cardiomyocyte injury were determined using an MTT assay, TUNEL staining, Annexin V/PI staining, lactate dehydrogenase and caspase activity. For statistical analysis, a value of P<0.05 was considered to be significant. Results: The effect of VEGF121 was found to be mediated by CaSR and calpain but was not dependent on calcium channels. Conclusions: Our findings, even though using an in vitro setting, lay the foundation for future validation and pre-clinical testing of VEGF-based gene therapy in cardiovascular diseases.

PURPOSE: To investigate the role of protein kinase G (PKG) in blocking post-shock mesenteric lymph (PSML) return ameliorating the calcium sensitivity in hemorrhagic shock rats. METHODS: Male Wistar rats were randomly divided into sham, shock, shock+ligation (shock plus mesenteric lymph duct ligation (MLDL)), shock+drainage (shock plus PSML drainage) groups. After shock (hypotension 40mmHg) for three hours or corresponding times, the superior mesenteric artery (SMA) was taken out for detecting the PKG and phospho PKG (p-PKG) contents, and the vascular rings of SMA were prepared for assaying the calcium sensitivity using an isolated organ perfusion system. RESULTS: The PKG and p-PKG contents of SMA in shock group were significantly increased than that of sham group, and MLDL or PSML drainage reducing the levels of PKG and p-PKG. Meanwhile, the vascular calcium sensitivity in shock group was significantly lower than that of sham group, MLDL or PSML drainage enhanced the calcium sensitivity. After incubating with PKG regulators in shock+ligation and shock+drainage groups, the PKG agonist 8Br-cGMP reduced the contractility of vascular rings to gradient calcium ions and Emax and the PKG inhibitor agonist KT5823 elevated the calcium sensitivity significantly. CONCLUSION: Protein kinase G plays an important role in post-shock mesenteric lymph blockage improving vascular calcium sensitivity.

Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein that mediates both NADH-oxidizing and caspase-independent apoptosis. Further, the proapoptotic activity of AIF is located in the C-terminus of AIF, although the precise minimum sequence responsible for apoptosis induction remains to be investigated. In the present study, we generated two truncated AIFs, AIFΔ1-480-FLAG, which is a FLAG-tagged C-terminal peptide comprising amino acids from 481 to 613, and AIF360-480 containing amino acids from 360 to 480 of AIF. We used confocal microscopy to demonstrate that both the truncated proteins are expressed and located in the cytoplasm of transfected cells. AIFΔ1-480 but not AIF360-480 induces apoptosis in transfected cells. We also found that the expression of AIFΔ1-480 could initiate the release of cytochrome c from the mitochondria. The suppression of caspase-9 via siRNA blocked the proapoptotic activity of AIFΔ1-480. Therefore, AIFΔ 1-480 is sufficient for inducing caspase-9-dependent apoptotic signaling, probably by promoting the release of cytochrome c. At last, we generated a chimeric immuno-AIFΔ 1-480 protein, which comprised an HER2 antibody, a Pseudomonas exotoxin A translocation domain and AIFΔ 1-480. Human Jurkat cells transfected with the immuno-AIFΔl-480 gene could express and secrete the chimeric protein, which selectively recognize and kill HER2-overexpressing tumor cells. Our study demonstrates the feasibility of the immuno-AIFΔl-480 gene as a novel approach to treating HER2-overexpressing cancers.