Generación de cardiomiocitos humanos a partir de células madre pluripotentes inducidas (iPSCs) generadas a partir de eritoblastos de sangre periférica

Objetivos del trabajo: 1) Generar y caracterizar líneas de iPSCs a partir de eritoblastos de sangre periférica humana de pacientes con Síndrome QT largo e individuos sanos control, por medio de la transducción con vectores virales conteniendo las regiones codificantes de los genes de los factores de transcripción OCT3/4, SOX2, KLF4 y c-MYC. 2) Diferenciar dichas líneas de iPSCs a cardiomiocitos con la finalidad futura de modelar in vitro esta cardiopatía y realizar estudios comparativos a nivel morfológico y funcional entre las células derivadas de individuos sanos y pacientes, así como testear posibles drogas.Facultad de Ciencias Médica

Generación de cardiomiocitos humanos a partir de células madre pluripotentes inducidas (iPSCs) generadas a partir de eritoblastos de sangre periférica

Objetivos del trabajo: 1) Generar y caracterizar líneas de iPSCs a partir de eritoblastos de sangre periférica humana de pacientes con Síndrome QT largo e individuos sanos control, por medio de la transducción con vectores virales conteniendo las regiones codificantes de los genes de los factores de transcripción OCT3/4, SOX2, KLF4 y c-MYC. 2) Diferenciar dichas líneas de iPSCs a cardiomiocitos con la finalidad futura de modelar in vitro esta cardiopatía y realizar estudios comparativos a nivel morfológico y funcional entre las células derivadas de individuos sanos y pacientes, así como testear posibles drogas.Facultad de Ciencias Médica

Generación de cardiomiocitos humanos a partir de células madre pluripotentes inducidas (iPSCs) generadas a partir de eritoblastos de sangre periférica

Objetivos del trabajo: 1) Generar y caracterizar líneas de iPSCs a partir de eritoblastos de sangre periférica humana de pacientes con Síndrome QT largo e individuos sanos control, por medio de la transducción con vectores virales conteniendo las regiones codificantes de los genes de los factores de transcripción OCT3/4, SOX2, KLF4 y c-MYC. 2) Diferenciar dichas líneas de iPSCs a cardiomiocitos con la finalidad futura de modelar in vitro esta cardiopatía y realizar estudios comparativos a nivel morfológico y funcional entre las células derivadas de individuos sanos y pacientes, así como testear posibles drogas.Facultad de Ciencias Médica

Lycopene and beta-carotene induce growth inhibition and proapoptotic effects on ACTH-secreting pituitary adenoma cells.

Pituitary adenomas comprise approximately 10-15% of intracranial tumors and result in morbidity associated with altered hormonal patterns, therapy and compression of adjacent sella turcica structures. The use of functional foods containing carotenoids contributes to reduce the risk of chronic diseases such as cancer and vascular disorders. In this study, we evaluated the influence of different concentrations of beta-carotene and lycopene on cell viability, colony formation, cell cycle, apoptosis, hormone secretion, intercellular communication and expression of connexin 43, Skp2 and p27(kip1) in ACTH-secreting pituitary adenoma cells, the AtT20 cells, incubated for 48 and 96 h with these carotenoids. We observed a decrease in cell viability caused by the lycopene and beta-carotene treatments; in these conditions, the clonogenic ability of the cells was also significantly decreased. Cell cycle analysis revealed that beta-carotene induced an increase of the cells in S and G2/M phases; furthermore, lycopene increased the proportion of these cells in G0/G1 while decreasing the S and G2/M phases. Also, carotenoids induced apoptosis after 96 h. Lycopene and beta-carotene decreased the secretion of ACTH in AtT20 cells in a dose-dependent manner. Carotenoids blocked the gap junction intercellular communication. In addition, the treatments increased the expression of phosphorylated connexin43. Finally, we also demonstrate decreased expression of S-phase kinase-associated protein 2 (Skp2) and increased expression of p27(kip1) in carotenoid-treated cells. These results show that lycopene and beta-carotene were able to negatively modulate events related to the malignant phenotype of AtT-20 cells, through a mechanism that could involve changes in the expression of connexin 43, Skp2 and p27(kip1); and suggest that these compounds might provide a novel pharmacological approach to the treatment of Cushing's disease

Mutations in Cytoplasmic Loops of the KCNQ1 Channel and the Risk of Life-Threatening Events Implications for Mutation-Specific Response to beta-Blocker Therapy in Type 1 Long-QT Syndrome

Background-beta-Adrenergic stimulation is the main trigger for cardiac events in type 1 long-QT syndrome (LQT1). We evaluated a possible association between ion channel response to beta-adrenergic stimulation and clinical response to beta-blocker therapy according to mutation location. Methods and Results-The study sample comprised 860 patients with genetically confirmed mutations in the KCNQ1 channel. Patients were categorized into carriers of missense mutations located in the cytoplasmic loops (C loops), membrane-spanning domain, C/N terminus, and nonmissense mutations. There were 27 aborted cardiac arrest and 78 sudden cardiac death events from birth through 40 years of age. After multivariable adjustment for clinical factors, the presence of C-loop mutations was associated with the highest risk for aborted cardiac arrest or sudden cardiac death (hazard ratio versus nonmissense mutations = 2.75; 95% confidence interval, 1.29-5.86; P=0.009). beta-Blocker therapy was associated with a significantly greater reduction in the risk of aborted cardiac arrest or sudden cardiac death among patients with C-loop mutations than among all other patients (hazard ratio=0.12; 95% confidence interval, 0.02-0.73; P=0.02; and hazard ratio=0.82; 95% confidence interval, 0.31-2.13; P=0.68, respectively; P for interaction=0.04). Cellular expression studies showed that membrane spanning and C-loop mutations produced a similar decrease in current, but only C-loop mutations showed a pronounced reduction in channel activation in response to beta-adrenergic stimulation. Conclusions-Patients with C-loop missense mutations in the KCNQ1 channel exhibit a high risk for life-threatening events and derive a pronounced benefit from treatment with beta-blockers. Reduced channel activation after sympathetic activation can explain the increased clinical risk and response to therapy in patients with C-loop mutations. (Circulation. 2012; 125: 1988-1996.

Clinical Aspects of Type 3 Long-QT Syndrome: An International Multicenter Study

Risk stratification in patients with type 3 long-QT syndrome (LQT3) by clinical and genetic characteristics and effectiveness of β-blocker therapy has not been studied previously in a large LQT3 population. The study population included 406 LQT3 patients with 51 sodium channel mutations; 391 patients were known to be event free during the first year of life and were the focus of our study. Clinical, electrocardiographic, and genetic parameters were acquired for patients from 7 participating LQT3 registries. Cox regression analysis was used to evaluate the independent contribution of clinical, genetic, and therapeutic factors to the first occurrence of time-dependent cardiac events (CEs) from age 1 to 41 years. Of the 391 patients, 118 (41 males, 77 females) patients (30%) experienced at least 1 CE (syncope, aborted cardiac arrest, or long-QT syndrome-related sudden death), and 24 (20%) suffered from LQT3-related aborted cardiac arrest/sudden death. The risk of a first CE was directly related to the degree of QTc prolongation. Cox regression analysis revealed that time-dependent β-blocker therapy was associated with an 83% reduction in CEs in females (P=0.015) but not in males (who had many fewer events), with a significant sex × β-blocker interaction (P=0.04). Each 10-ms increase in QTc duration up to 500 ms was associated with a 19% increase in CEs. Prior syncope doubled the risk for life-threatening events (P <0.02). Prolonged QTc and syncope predispose patients with LQT3 to life-threatening CEs. However, β-blocker therapy reduces this risk in females; efficacy in males could not be determined conclusively because of the low number of event

ACTH secretion by AtT-20 cells.

<p>Cells were treated with 5 and 10 µM of beta-carotene or lycopene for a period of 24 h, and ACTH levels were determined in the supernatant by immunoassay. The treatment reduced the ACTH secretion in a dose-dependent manner. Data are expressed as mean±standard deviation pg/mL, of 3 independent experiments, each performed with at least 2 replicates. *indicates significant differences from control group. (*<i>p</i><0.05, **<i>p</i><0.01, ***<i>p</i><0.001).</p