The first successful report of using cell-depleted lung as a natural growth matrix（矩阵，模型） for generating new rat lung from embryonic¹ stem cells is presented in a breakthrough article in Tissue Engineering, Part A, a peer-reviewed journal published by Mary Ann Liebert, Inc. (www.liebertpub.com). The article is available free online at www.liebertpub.com/ten Embryonic stem cells (ESCs) have the potential to mature into virtually any type of cell and tissue type, but they require an appropriate environment and chemical signals to drive their differentiation²（变异，分化） into specific cell types and to form 3-dimensional tissue structures. Alternatives to available synthetic³ tissue matrices are needed to drive this technology forward and develop clinical applications for engineered lung tissue.

Joaquin Cortiella, MD, MPH, and colleagues from University of Texas Medical Branch (Galveston), Stanford University (Palo Alto, CA), Brown Medical School (Providence, RI), and Duke University (Durham, NC), describe the first attempt to make acellular（非细胞的） rat lung and use it as a biological matrix for differentiating⁵ ESCs into lung tissue. The authors present evidence of improved cell retention⁶（保留，扣留） , repopulation of the matrix, and differentiation into the cell types present in healthy lung. They also report signs that the cells are organizing into the 3-D structures characteristic of complex tissues and are producing the chemical signals and growth factors that guide lung tissue function and development.

Cortiella and coauthors describe the process used to remove the cellular⁴ component⁷ of natural lung tissue and create a growth matrix for ESCs in the article, "Influence of Acellular Natural Lung Matrix on Murine Embryonic Stem Cell Differentiation and Tissue Formation."

"Organ-specific extracellular matrices, properly prepared, are serving more and more as the appropriate structural⁸ scaffold（脚手架） for the recapitulation of a specific organ's tissues. This turns out to be especially true in an organ such as the lung, whose parenchyma（实质，软细胞组织） must have a structure that accommodates atmospheric⁹ gas transmission as well as vascular¹⁰（血管的） , lymphatic（淋巴的） , and neural¹¹ systems," says Peter C. Johnson, MD, Co-Editor-in-Chief of Tissue Engineering and Vice¹² President, Research and Development, Avery Dennison Medical Products.