干细胞 z-bo 2020-09-19 348

　　If you look through a microscope, you will see a piece of image data of a human heart beating, each heart is driving its ventricles. These tiny organs are only 1 millimeter in diameter. They are the first three-dimensional "heart-shaped" organs made by scientists using individual stem cells.

　　"The contractions of these hearts cannot be seen with the naked eye, so we call them micro-hearts." said Zhen Ma of the University of California, Berkeley. These organs have also been made before, but they all use existing structures to fix new cells in place, such as made from a collagen matrix left behind after the cells are stripped from a donor heart, or made by 3D printing .

　　Ma uses induced pluripotent stem cells to form heart organs by turning ordinary skin cells back into primitive, embryonic cells. Under normal circumstances, researchers will use growth factors alone to induce such stem cells to form specialized cells in the organs, but Ma's research team used another technique.

　　In order to simulate the physical forces that usually tell fetal stem cells where and where they cannot grow, the researchers etched a chemical "no-pass zone" by punching holes in a petri dish. These holes allow stem cells to accumulate into the proper shape.

　　This process changes the shape of the cells by mimicking what happens when the real heart is in the developing embryo. Therefore, those cells in the center of the hole become a beating heart cell called a cardiomyocyte. Cardiomyocytes are surrounded by fibroblasts similar to skin cells, which form the connective tissue of the heart. More notably, the cardiomyocytes will grow and form a dome-shaped cavity-the microscopic ventricle.

　　"Our model has taken the first step in using the self-organization of cells to construct a heart, and does not require any external three-dimensional support materials." Ma said that the ultimate goal of the research is to construct a heart organ of real size.