Grupo consegue criar tecido cardíaco em laboratório

DA REPORTAGEM LOCAL FSP

Um grupo de pesquisadores americanos, canadenses e britânicos anunciou ontem ter conseguido produzir três tipos diferentes de tecido cardíaco em laboratório usando células-tronco embrionárias. O sucesso de um experimento com camundongos, descrito em estudo publicado ontem no site da revista "Nature", torna mais próxima a meta de usar a técnica para tratar vítimas de infarto no futuro.
Os cientistas, liderados por Gordon Keller, do Centro McEwen, de Toronto, alimentaram células-tronco de embriões com proteínas específicas ao longo de seu desenvolvimento para fazer com que elas adquirissem as características desejadas.
Foram criadas células de músculo cardíaco (que bombeia o sangue), células musculares que fazem parte dos vasos sangüíneos e células de endotélio (revestimento interno) de artérias. Em um vídeo, é possível ver um punhado de células "batendo".
Ao implantar as células em roedores com doença cardíaca, os animais melhoraram, relata o estudo na "Nature".

Human cardiovascular progenitor cells develop from a KDR⁺ embryonic-stem-cell-derived population

Lei Yang et al. Published online 23 April 2008 , Nature
he functional heart is comprised of distinct mesoderm-derived lineages including cardiomyocytes, endothelial cells and vascular smooth muscle cells. Studies in the mouse embryo and the mouse embryonic stem cell differentiation model have provided evidence indicating that these three lineages develop from a common Flk-1⁺ (kinase insert domain protein receptor, also known as Kdr) cardiovascular progenitor that represents one of the earliest stages in mesoderm specification to the cardiovascular lineages¹. To determine whether a comparable progenitor is present during human cardiogenesis, we analysed the development of the cardiovascular lineages in human embryonic stem cell differentiation cultures. Here we show that after induction with combinations of activin A, bone morphogenetic protein 4 (BMP4), basic fibroblast growth factor (bFGF, also known as FGF2), vascular endothelial growth factor (VEGF, also known as VEGFA) and dickkopf homolog 1 (DKK1) in serum-free media, human embryonic-stem-cell-derived embryoid bodies generate a KDR^low/C-KIT(CD117)^neg population that displays cardiac, endothelial and vascular smooth muscle potential in vitro and, after transplantation, in vivo. When plated in monolayer cultures, these KDR^low/C-KIT^neg cells differentiate to generate populations consisting of greater than 50% contracting cardiomyocytes. Populations derived from the KDR^low/C-KIT^neg fraction give rise to colonies that contain all three lineages when plated in methylcellulose cultures. Results from limiting dilution studies and cell-mixing experiments support the interpretation that these colonies are clones, indicating that they develop from a cardiovascular colony-forming cell. Together, these findings identify a human cardiovascular progenitor that defines one of the earliest stages of human cardiac development.