Chemistry

Shepherding Stem Cells

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Science  17 May 2013:
Vol. 340, Issue 6134, pp. 789
DOI: 10.1126/science.340.6134.789-a

Stem cells, because of their ability to differentiate into multiple cell types, are of interest in aiding tissue repair and for treating diseases such as diabetes. However, their lack of specificity also makes it hard to guide them to the target tissue of concern. Leukocytes express transmembrane receptors that will bind with overexpressed proteins on damaged or pathologic tissues. Using this as their model, Jeong et al. synthesized a hyperbranched polyglycerol (HPG) that was covalently modified with octadecyl chains and vasculature binding peptides of sequence VHSPNKK, chosen for its binding affinity toward vascular endothelial adhesion molecules overexpressed by inflamed blood vessels. The modified HPG showed an affinity to bind to cell surfaces but without interfering with the metabolic activity of the cells. Two types of adiposederived mesenchymal stem cells (MSCs) were used in a flow cell across an endothelial cell sheet that had been exposed to tumor necrosis factor–α. The peptide-modified HPG decreased the rolling rate of the MSCs and increased the adhesion of the cells to the endothelium, although only by a factor of 2.

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J. Am. Chem. Soc. 135, 10.1021/ja400636d (2013).

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