New study directs stem cell growth



A recent study by Yale researchers has determined a new, more effective technique for guiding the development of neuronal cells by manipulating the environment in which the cells grow.

This technique may be useful in the treatment of spinal cord injuries and neurological disorders such as Parkinson’s disease.

W. Mark Saltzman, chair of the Yale biomedical engineering department, and other Yale researchers focused on directing stem cell development by manipulating the surface on which the cells grow, called the cell substrate.

By using mesenchymal cells — stem cells procured from bone marrow — and by mimicking cell surfaces found in the human body, researchers were better able to direct the stem cell transformation into neuronal cells.

“We found the most effective technique was using a mixture of proteins that are normally found in the extra-cellular matrix,” Saltzman said.

More complex manipulations of the cell substrate are also being explored, such as micro-patterning to better predict cell migration and orientation.

Stem cells have been a popular research topic in recent years. Not yet predetermined to develop into a certain cell type, stem cells can theoretically develop into any kind of cell in the body.

“There is a tremendous amount of interest in stem cells,” Saltzman said. “But part of the problem is realizing their application, to guide the stem cells that have the potential to become the type of cells you’re looking for.”

There are various other techniques currently used to guide stem cell development. The most common technique is to manipulate the liquid medium in which the cells grow by infusing it with hormones and nutrients. Another approach is to culture the stem cells with mouse “feeder cells,” however Saltzman said this process is less efficient because the human cells are often contaminated by the foreign cells.

Although he has not applied his technology to specific diseases, Saltzman said he hopes his research will have far reaching affects.

“We’ve just been using it as a model to show you can guide the fate of cells,” he said. “We hope some of the things we are doing in my lab might be used by other groups to treat diseases.”

Similar technology is currently being explored by another Yale researcher, Erin Lavik, assistant professor of Biomedical Engineering. Lavik is studying spinal cord injury repair. Such injuries effect 10,000 Americans annually.

Lavik, using paralyzed rats, created substrates that mimic the structural design of a healthy spinal cord, into which neural stem cells were implanted.

“We used polymer scaffolds — made of biodegradable materials that actually [dissolve],” Lavik said. “These create the right environment for integration and differentiation of stem cells and then get out of the way.”

In Lavik’s research, the rats showed significant functional recovery, exhibiting weight-bearing stepping .

This research is the first to show dramatic progress in the treatment of such injuries, but the technology must be developed further before its is applied to humans.

“It’s much easier to repair [spinal cord injuries in] rodents than it is in humans,” Lavik said. “Rodents have functional recovery with much less tissue than in humans — we have to augment the [technology] before we’re ready to repair [spinal cord damage] in higher-level organisms.”

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