Northwestern University researchers have created a miniature laboratory—a strong, flexible sac—into which they can grow human stem cells. The sacs can survive for weeks in culture and the membranes are permeable to proteins. This new mode of self-assembly, to be published March 28 in the journal Science, was developed by researchers at Northwestern’s Institute for BioNanotechnology in Medicine. The method holds promise for use in cell therapy and other biological applications.

Two molecules were each dissolved in water. One was a peptide amphiphile (PA), small synthetic molecules, which have been essential in work on regenerative medicine. The other molecule is the biopolymer hyaluronic acid (HA), which is readily found in the human body, in places like joints and cartilage.

Using just these two molecules, the researchers can make many different structures, including sacs, which have a solid membrane on the outside and liquid inside, and flat membranes of any shape. The researchers can make the structures large or small, pick up the material with tweezers, stretch it and even easily repair the sacs through self-assembly should the material tear or have some other defect. The sacs also are robust enough to be sutured by surgeons to biological tissues.

The large (hyaluronic acid) and small (peptide amphiphile) molecules come together through supramolecular interactions, not by chemical reaction, in which covalent bonds are formed.

Release Date: March 27, 2008
Source: Northwestern University