p53 mediated mesenchymal-to-endothelial transition is a novel mechanism of vasculogenesis after ischemic cardiac injury

The mammalian heart displays limited regenerative capacity after acute ischemic injury and heals primarily through fibrosis. Recent therapeutic research has focused on increasing vasculature at the site of injury as a means of preserving remaining myocardium and improving cardiac function after injury. Other research has focused on the ability to reprogram cardiac fibroblasts using exogenous transcription factors to achieve a similar goal. However, the ability of cardiac fibroblasts to adopt alternate cellular fates in the absence of exogenous factors is unclear. Here, we demonstrate that a subset of cardiac fibroblasts adopts the physiological and anatomical characteristics of native endothelial cells after ischemic cardiac injury in the absence of any added factors. Using mice harboring genetically labeled fibroblasts (Col1a2-CreERT:R26RtdTomato), we show that approximately 30% of labeled cardiac fibroblasts in the injury border zone express endothelial markers such as VE-cadherin, eNOS, Occludin, and Claudin 5. Fibroblast derived endothelial cells comprised 25+/-2% of total luminal endothelial cells at the border zone 3 days after injury. To better understand fibroblast-endothelial transition we subjected cardiac fibroblasts to cellular stress (serum starvation) and found that they formed endothelium-like structures on Matrigel and up-regulated endothelial specific genes (e.g. VE-cadherin, Flk1, Flt1) 6-20 fold. We show that transition of fibroblasts to endothelial-like cells ex vivo is p53 dependent. Pharmacological inhibition of p53 using Pifithrin-α or genetic deletion in fibroblasts (Col1a2-CreERT:p53fl/fl) led to a 94% mean decrease in Matrigel tube formation and 90% reduction in endothelial gene expression. Moreover, using semi-quantitative immunofluorescent staining, we observed that p53 levels in cardiac fibroblasts were more than 6 fold higher at the injury border zone. Injection of a p53 activator, RITA, after injury doubled p53 levels in cardiac fibroblasts and increased the degree of mesenchymal-to-endothelial transition (MEndoT) by 43%. Enhanced MEndoT was also associated with decreased collagen deposition and improved heart function 7 days post injury. In summary, we show that cardiac fibroblasts adopt endothelial cell like fates after cardiac injury and contribute to the neovascularization of the injured region. Manipulation of MEndoT could represent a novel therapeutic strategy to increase post infarct angiogenesis and enhance function in the injured heart.Doctor of Philosoph

Cardiac fibroblast in development and wound healing

Cardiac fibroblasts are the most abundant cell type in the mammalian heart and comprise approximately two-thirds of the total number of cardiac cell types. During development, epicardial cells undergo epithelial-mesenchymal-transition to generate cardiac fibroblasts that subsequently migrate into the developing myocardium to become resident cardiac fibroblasts. Fibroblasts form a structural scaffold for the attachment of cardiac cell types during development, express growth factors and cytokines and regulate proliferation of embryonic cardiomyocytes. In post natal life, cardiac fibroblasts play a critical role in orchestrating an injury response. Fibroblast activation and proliferation early after cardiac injury are critical for maintaining cardiac integrity and function, while the persistence of fibroblasts long after injury leads to chronic scarring and adverse ventricular remodeling. In this review, we discuss the physiologic function of the fibroblast during cardiac development and wound healing, molecular mediators of activation that could be possible targets for drug development for fibrosis and finally the use of reprogramming technologies for reversing scar. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium.

Mesenchymal–endothelial transition contributes to cardiac neovascularization

Endothelial cells contribute to a subset of cardiac fibroblasts by undergoing endothelial-to-mesenchymal-transition, but whether cardiac fibroblasts can adopt an endothelial cell fate and directly contribute to neovascularization after cardiac injury is not known. Here, using genetic fate map techniques, we demonstrate that cardiac fibroblasts rapidly adopt an endothelial cell like phenotype after acute ischemic cardiac injury. Fibroblast derived endothelial cells exhibit anatomical and functional characteristics of native endothelial cells. We show that the transcription factor p53 regulates such a switch in cardiac fibroblast fate. Loss of p53 in cardiac fibroblasts severely decreases the formation of fibroblast derived endothelial cells, reduces post infarct vascular density and worsens cardiac function. Conversely, stimulation of the p53 pathway in cardiac fibroblasts augments mesenchymal to endothelial transition, enhances vascularity and improves cardiac function. These observations demonstrate that mesenchymal-to-endothelial-transition contributes to neovascularization of the injured heart and represents a potential therapeutic target for enhancing cardiac repair

Treatment of industrial wastewater using constructed wetland : removal of orthophosphate and ammonia nitrogen

Industrial wastewater is one of the major concerns of the environment problems. As the wastewater is found to be highly contaminated, it could not be discharged directly into the environment. Therefore, wastewater treatment is essential to minimize the effect of the contaminants to nature. Based on previous studies, constructed wetland system (CWS) was proved to have high efficiency in treating industrial wastewater with low operating and maintenance cost. The industrial wastewater studied was Palm Oil Mill Effluent (POME) which was taken from Lepar Hilir Palm Oil Mill. In this research, lab scale of free water surface constructed wetlands was designed with the water lettuce (Pistia Stratiotes) as the wetland plant. The parameter studied including ammonia nitrogen (NH 3-N) and orthophosphate (Po 4 3- ). In order to investigate the effectiveness of the systems, three variables were studied which were the number of plant used (5, 10, 15), the wastewater concentration (87.5%, 75%, 62.5%) and the physical appearance of the plants during the treatment. The results showed that NH3-N was removed at high removal efficiency meanwhile Po 4 3- removal appeared at low removal efficiency. Both NH 3-N and Po 4 3- removal showed better results in the CWS with 15 plants. In term of the different POME concentration variable, the CWS with 87.5% showed the highest removal efficiency for NH -N and 75% POME concentration showed the highest removal efficiency for Po 3 4 3- . For plant growth observation, at the end of the treatment, many of the water lettuces were wilted. As conclusion, this study showed that constructed wetland can remove contaminant in POME

Hydrogen as Carbon Gasifying Agent During Glycerol Steam Reforming over Bimetallic Co-Ni Catalyst

Alumina-supported bimetallic cobalt-nickel catalyst has been prepared and employed in a fixed-bed reactor for the direct production of synthesis gas from glycerol steam reforming. Physicochemical properties of the 5Co-10Ni/85Al2O3 catalyst were determined from N2-physisorption, H2-chemisorption, CO2 and NH3-temperature-programmed desorption measurements as well as X-ray diffraction analysis. Both weak and strong acid sites are present on the catalyst surface. The acidic:basic ratio is about 7. Carbon deposition was evident at 923 K; addition of H2 however has managed to reduce the carbon deposition. Significantly, this has resulted in the increment of CH4 formation rate, consistent with the increased carbon gasification and methanation. Carbon deposition was almost non-existent, particularly at 1023 K. In addition, the inclusion of hydrogen also has contributed to the decrease of CO2 and increase of CO formation rates. This was attributed to the reverse water-gas-shift reaction. Overall, both the CO2:CO and CO2:CH4 ratios decrease with the hydrogen partial pressure

Cardiac fibroblast in development and wound healing

Cardiac fibroblasts are the most abundant cell type in the mammalian heart and comprise approximately two-thirds of the total number of cardiac cell types. During development, epicardial cells undergo epithelial-mesenchymal-transition to generate cardiac fibroblasts that subsequently migrate into the developing myocardium to become resident cardiac fibroblasts. Fibroblasts form a structural scaffold for the attachment of cardiac cell types during development, express growth factors and cytokines and regulate proliferation of embryonic cardiomyocytes. In post natal life, cardiac fibroblasts play a critical role in orchestrating an injury response. Fibroblast activation and proliferation early after cardiac injury are critical for maintaining cardiac integrity and function, while the persistence of fibroblasts long after injury leads to chronic scarring and adverse ventricular remodeling. In this review, we discuss the physiologic function of the fibroblast during cardiac development and wound healing, molecular mediators of activation that could be possible targets for drug development for fibrosis and finally the use of reprogramming technologies for reversing scar. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium.

Kajian morfologi pada beberapa hablur yang mempunyai struktur simetri yang tinggi

Kajian ini merupakan kajian morfologi terhadap bahan yang mempunyai simetri tinggi. Tiga bahan simetri tinggi yang dikaji iaitu, Natrium Klorida (NaCl), Kromium (Cr) dan Ferum (Fe). Dalam kajian ini Mikroskop Elektron Pengimbas (SEM) digunakan untuk melihat struktur permukaan Natrium Klorida, Kromium dan Ferum. Melalui kaedah ini sampel disaluti dengan emas atau platinum untuk mendapatkan kekonduksian bahan yang sebenar tanpa campuran bendasing. Ini adalah bertujuan untuk memudahkan pengecaman bentuk permukaan bahan. Struktur permukaan yang diperolehi adalah langkah awal untuk menjalankan kajian-kajian seterusnya. Pemerhatian dilakukan pada permukaan Natrium Klorida, Kromium dan Ferum dengan meneliti ciri-ciri seperti susunan, taburan, saiz, permukaan, dan bentuk setiap unit yang terkandung dalam ketiga-tiga bahan ini. Struktur permukaan Natrium Klorida, Kromium dan Ferum adalah mudah untuk dispesifikasikan. Natrium Klorida (NaCl), mempunyai permukaan yang lebih tersusun dan mempunyai permukaan yang rata, ini adalah kerana jumlah daripada jadual berkala, nombor atom NaCI ialah 28, yang bermaksud petala terluar mempunyai bilangan elektron yang lengkap (2.8.18). Manakala Kromium pula mempunyai permukaan yang kasar dan kurang rata, berikutan dengan nombor atom bagi Kromium iaitu 24, yang menyebabkan bilangan elektron di petala luar yang tidak lengkap iaitu (2.8.14). Ferum mempunyai permukaan yang kasar, tidak rata dan bercelah, ini adalah kerana ia mempunyai bilangan elektron di petala luar yang tidak lengkap (2.8.16), berdasarkan kepada nombor atom iaitu 26