8
nanotimes
10-01 :: January 2010
Research
Stem Cell Growth //
3-D Scaffold Provides Clean, Biodegradable Structure
S
cientists at the University of Washington have Different processing techniques can make the scaf-
now created an alternative to get stem cells to fold out of interconnected pores of almost any size,
multiply. Most research labs still use animal-based Zhang said.
„feeder layers“ because it remains the cheapest and
most reliable way to get stem cells to multiply. Researchers first seeded the scaffold with 500,000
embryonic stem cells, and after 21 days the scaffold
The material scientists built a three-dimensional scaf- was completely saturated. The cells infiltrated the
fold out of a natural material that mimics the binding structure, Zhang added, unlike other materials where
sites for stem cells, allowing the cells to reproduce on cells often grow only on the surface.
a clean, biodegradable structure. Results show that
human embryonic stem cells grow and multiply „This scaffold mimics the extracellular matrix at the
readily on the structure. atomic level, and so the cells are able to grow in this
environment,“ Zhang said.
„The major challenge for stem cell therapy today is
it‘s very difficult to make a lot of them with high pu- To retrieve the cells, researchers immersed the scaf-
rity,“ said lead author Miqin Zhang, a UW professor fold in a mild solution. The structure is biodegradable
of materials science and engineering. „So far it seems and so dissolved to release the stem cells. One also
like this material is very good for stem cell renewal.“ could implant the stem cell-covered scaffold directly
into the body. Analysis of gene activity and testing in
„Three-dimensional scaffolds are an active area of the lab and in mice showed that the new stem cells
research,“ said Carol Ware, a UW professor of com- retained the same properties as their predecessors.
parative medicine and expert on stem cells. „They Other researcher groups are also looking for alter-
are not commonly used yet, but will be important to natives to feeder layers. The leading contenders are
transition embryonic stem cells to the clinic. To date, scaffolds coated with custom proteins designed to
nobody has found a perfect matrix.“ mimic the key properties of the animal cells in the
feeder layer. Such products are expensive and diffi-
Zhang‘s cylindrical scaffold is made of chitosan, cult to produce in a consistent manner, Zhang said.
found in the shells of crustaceans, and alginate, a The proteins also get used up in a few days and have
gelatinous substance found in algae. Chitosan and to be replaced, making them costly and time-consu-
alginate have a structure similar to the matrix that ming for everyday use.
surrounds cells in the body, to which cells can attach.