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With the potential to differentiate into any type of cell, embryonic stem cells are attractive for many uses, including tissue engineering. Getting these cells to develop into viable three-dimensional tissues is difficult, however. SUPPORTS Polymer scaffolds, shown here with (bottom) and without embryonic stem cells, undergird the formation of 3-D tissue structures. © 2003 PNAS Postdoc Shulamit Levenberg and chemical engineering professor Robert S. Langer of MIT and their coworkers have now shown that they can use biodegradable polymer scaffolds to grow 3-D tissues from embryonic stem cells [Proc. Natl. Acad. Sci., USA, published online Oct. 15, http://www.pnas.org/cgi/doi/10.1073/pnas.1735463100]. The cells can be made to stick to the scaffold using a commercial matrix known as matrigel or by coating the scaffold with fibronectin, a glycoprotein that regulates cell attachment, growth, and differentiation. Depending on the growth factors added, the researchers prod the cells to form 3-D structures having the characteristics of neural, cartilage, or liver tissues. When implanted in immunodeficient mice, the tissues remain viable and begin to integrate with the animals' vasculature. This study shows that the polymer scaffold plays a role in cell differentiation and organization by providing a specific 3-D environment. Other materials and even embryo-like structures don't provide similar results, according to Langer. Langer's group "has demonstrated the ability to employ morphological cues, adsorbed adhesion cues, and soluble growth factor cues" to direct the differentiation of embryonic stem cells, says Jeffrey A. Hubbell, a professor of biomedical engineering at the Swiss Federal Research Institute, Lausanne. "Using these approaches with designs that have been presented for more advanced biomaterials, it should be possible to gain even firmer control in directing the differentiation of embryonic stem cells." |
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