Synthetic ‘cradle’ boosts hope of stem cell therapies
“For therapeutics, you need millions and millions of cells,” says Dr Krishanu Saha from the Whitehead Institute for Biomedical Research. “If we can make it easier for the cells to divide and grow, that will really help to get the number of cells you need to do all of the disease studies that people are excited about.”
Now, thanks to Saha and colleagues, the situation could be about to change. They’ve created a new synthetic ‘cradle’ for stem cells that improves their ability to multiply, untransformed, and stay in better shape for medical applications.
Currently stem cells are grown in a plastic dish coated with a layer of gelatin and a layer of mouse cells or proteins. This is notoriously inefficient and makes it difficult to identify and manipulate individual cells genetically. Moreover, the use of material derived from animals, such as the mouse cells, means that any transplantation to humans runs the risk of rejection by the immune system.
Saha and colleagues have developed a better way. Their synthetic foundation allows single stem cells to form colonies of identical cells, making it easier to identify those with desirable traits.
After testing around 500 different synthetic polymers, the scientists settled on one optimised for factors such as flexibility, roughness and its affinity for water (which can affect the behaviour of stem cells). Stem cells can bind quickly and securely to this polymer’s surface.
Moreover, the supporting media used to maintain and nourish the cells is free of animal components. And because the components of the system are well defined, scientists have a better idea of what their stem cells have been exposed to.
The polymer supports the growth of cells obtained from human embryos (i.e. human embryonic stem cells) or reprogrammed adult cells (i.e. induced pluripotent stem cells). Tests have shown that such cells can survive for over two months on the polymer, which bodes well for its use in long-term cell culture.
That makes achieving some of the more attractive applications of stem cells more feasible, such as growing new neurons for patients with spinal cord injuries or new insulin-producing cells for those with type 1 diabetes.
The researchers are now in talks with several companies about the technology, with the aim of making the polymer available to scientists as soon as possible.
In the meantime, they are working to refine their method, build materials to grow other types of cells, and better define what it takes to get stem cells to grow successfully.
- Mei, Y., Saha, K., Bogatyrev, S., Yang, J., Hook, A., Kalcioglu, Z., Cho, S., Mitalipova, M., Pyzocha, N., Rojas, F., Van Vliet, K., Davies, M., Alexander, M., Langer, R., Jaenisch, R., & Anderson, D. (2010). Combinatorial development of biomaterials for clonal growth of human pluripotent stem cells Nature Materials, 9, 768-778