Guidance system for stem cells
How to put stem cells in place?
ChemPort.Ru based on Chemical & Engineering News: Putting Stem Cells In Their PlaceIn people suffering from chronic diseases such as diabetes and multiple sclerosis, thinned vessels are often inflamed, which significantly increases the risk of heart attack and stroke.
A number of researchers hope that using the patient's own stem cells to re-grow healthy tissue can suppress inflammatory processes and restore the vessels to their healthy state. The new polymer coating may turn out to be a guide that will help stem cells find inflamed endothelial tissue and attach to it.
The stem cell guidance system consists of a hyperbranched polymer modified with peptides binding to the tissues of the cardiovascular system and lipophilic octadecyl chains. Upon contact with stem cells, octadecyl chains bind to cell membranes, and peptides bind to the cell surface of blood vessels.
Targeting stem cells to certain tissues, such as the inner walls of inflamed blood vessels, is a complex process, since after injection into the patient's bloodstream, the cells quickly spread throughout the body. A number of researchers have previously made attempts to force stem cells to attach to certain types of tissue. However, as Hyunjoon Kong from the University of Illinois notes, the stem cell management techniques currently developed are time-consuming and in some cases can kill cells. The researcher emphasizes that the goal of his research group was to find a molecule that could self-organize with stem cells and direct them to the desired tissue. According to him, if such a molecule could be developed, it would allow the doctor to simply mix the patient's stem cells with a "magic" molecule and inject this mixture into the patient's bloodstream.
Kong and co-authors synthesized a molecule containing peptides specifically binding to proteins distributed on the inner surface of inflamed vessels. These peptides were associated with branched glycerin-based polymers, which played the role of a template for the placement of peptides.
To link the system to stem cells, the researchers modified hyperbranched polymers with lipophilic octadecyl fragments that can spontaneously embed into the lipid membrane of cells.
To test the capabilities of the new molecules, the researchers injected a mixture of the resulting compound and mesenchymal stem cells into a microcapillary that simulated an inflamed blood vessel. The device distilled a mixture of cells and molecules over a colony of endothelial cells depicting inflamed tissue, and the researchers counted the number of stem cells attached to a "section of inflamed tissue." Compared to unmodified stem cells, cells coated with a new molecule were attached to the desired site twice as often.
Despite the already noted advantage of the new system, Kong emphasizes that he will be able to make the system even more selective and efficient by changing the structure of the hyperbranched polymer, which would allow peptides and hydrocarbon residues not to interfere with each other.
Article by Jeong et al. Leukocyte-Mimicking Stem Cell Delivery via in Situ Coating of Cells with a Bioactive Hyperbranched Polyglycerol is published in the Journal of American Chemical Society.
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