Self-assembly of molecules may offer new therapeutic treatments

February 15th, 2009 - 4:07 pm ICT by ANI  

Washington, February 15 (ANI): Northwestern University researchers have come up with an approach to deal with some of the major health problemsgather raw materials and then let them self-assemble into structures that can address a multitude of medical needs.
Samuel I. Stupp, whose laboratory has devised the novel approach, says that at the core of the research are peptide amphiphiles (PA), small synthetic molecules that Stupp first developed seven years ago, which have been essential in his work on regenerative medicine.
The researcher says that tailoring these molecules and combining them with others can help make a wide variety of structures that may provide new treatments for medical issues including spinal cord injuries, diabetes and Parkinson’’s disease.
Ramille M. Capito, a research assistant professor in Stupp’’s lab, recently discovered that combining the PA molecules with hyaluronic acid (HA), a biopolymer readily found in the human body in places like joints and cartilage, resulted in an instant membrane structure in the form of self-assembling sacs.
During a presentation at the American Association for the Advancement of Science (AAAS) Annual Meeting in Chicago on Saturday, the researchers revealed that they had found the sac membrane to have hierarchical order from the nanoscale to microscale giving it unique physical properties.
Writing as to how they created a sac in the journal Science, the researchers revealed that they took advantage of the fact that HA molecules are larger and heavier than the smaller PA molecules.
In a deep vial, Capito pipetted the PA solution and onto that injected the HA solution.
She revealed that, as the heavier molecules sank, the lighter molecules engulfed them and created a closed sac with the HA solution trapped inside the membrane.
After creating the sacs, Capito studied human stem cells engulfed by the self-assembly process inside sacs that she placed in culture, and found that the cells remained viable for up to four weeks, that a large protein — a growth factor important in the signalling of stem cells — could cross the membrane, and that the stem cells were able to differentiate.
Making a clever demonstration of self-repair, if the sac’’s membrane had a hole, Capito simply placed a drop of the PA solution on the tear, which interacted with the HA inside, resulting in self-assembly and a sealed hole.
While the underlying, highly ordered structures of the sacs and membranes have dimensions on the nanoscale, the sacs and membranes themselves can be of any dimension and are visible to the naked eye.
The researchers say that such sacs can be tailored to include bioactive regions, which would allow them to incorporate a variety of designs into one sac structure.
According to them, this capability opens the door to the creation of new methods for stem cell delivery. Stem cells can be loaded in the sac, which can be tailored to release the cells at the point of injury, they add. (ANI)

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