Scientists interested in engineering tissue would like to find a way to get cells and other biological components to organize and assemble into an organ similar to the way they do naturally.
At the Harvard’s Wyss Institute, Peng Yin, an assistant professor of systems biology, and his team found a way program DNA to act a glue that encourages gel-like cubes smaller than salt grains to self-assemble into larger structures. The cubes could be programmed to form scaffolding that hosts cells, which eventually grow into organs.
The self-assembly works because of the way DNA sticks together. DNA is made of four molecules, called bases. They are adenine, guanine, cytosine and thymine, or A, G, C and T. To come together into the familiar ladder-like, double-helix structure of DNA, the molecules have to link in a specific order. The “rungs” of the ladder have to be either A linked to T or G linked to C. So, if a string of bases on one side of the double helix ladder is AGCT, the rung on the other has to be TCGA. Other combinations will not bind to it. This binding property makes DNA perfect as a biological glue.
Knowing this, the Wyss team coated cubes of hydrogel, a water-based gel compatible with the human body, with specific pairs of DNA base molecules and arranged them so that the half-rungs of the ladder stuck out. Next, they put the cubes in a liquid solution containing other molecules. The cubes only attached to “partners” cubes that were coated with complementary DNA. With this technique, the scientists were able to build crosses and squares. And according to the researchers, there’s no reason they couldn’t make more complicated shapes. The idea is that one day, DNA-coated hydrogels could be injected into patients that have organ damage. The hydogels would self-assemble into the appropriate shape and attract cells to grow on them, forming repair tissue.
The experiments appeared in the Sept. 9 issue of the journal Nature Communications.
via Wyss Institute
Credit: Peng Yin, Wyss Institute