Times of India
27 March 2010

Scientists create a material from fat cells that can, someday, be used along with stem cells to repair tissues and even organs, without fear of rejection
It frequently happens in science that what you throw away turns out to be most valuable. It happened to Deepak Nagrath, a professor of chemical and biomolecular engineering at Rice university. He was looking for ways to grow cells in a scaffold, and he discarded the sticky substance secreted by the cells.

“I thought it was contamination, so I threw the plates away,” said Nagrath. That substance, derived from adipose cells – aka body fat – turned out to be a natural extracellular matrix, the very thing he was looking for.

Nagrath and his co–authors have since built a biological scaffold that allows cells to grow and mature. He hopes the new material, when suffused with stem cells, will someday be injected into the human body, where it can repair tissues of many types without fear of rejection.

The research has appeared in the Federation of American Societies for Experimental Biology Journal.

The basic idea is simple: Prompt fat cells to secrete what bioengineers call “basement membrane.” This membrane mimics the architecture tissues naturally use in cell growth, literally a framework to which cells attach while they form a network. When the cells have matured into the desired tissue, they secrete another substance that breaks down and destroys the scaffold.

Structures that support the growth of living cells into tissues are highly valuable to pharmaceutical companies for testing drugs in vitro. Companies commonly use Matrigel, a protein mixture secreted by mouse cancer cells, but for that reason it can’t be injected into patients.

“Fat is one thing, in excess that we can always lose it,” Nagrath said.

The substance derived from the secretions, called Adipogel, has proven effective for growing hepatocytes – primary liver cells. “My approach is to force the cells to secrete a natural matrix,” he said.

That matrix is a honey–like gel that retains the natural growth factors, cytokines (substances that carry signals between cells) and hormones in the original tissue.

Nagrath’s strategy for growing cells isn’t the only approach being pursued: Another method reported last week in Nature Nanotechnology uses magnetic levitation to grow three–dimensional cell cultures. But Nagrath is convinced his strategy is ultimately the most practical for rebuilding tissue, and not only because it may cost significantly less than Matrigel.

“The short–term goal is to use this as a feeder layer for human stem cells. It’s very hard to maintain them in the pluripotent state (where they keep dividing and are self–renewing),” he said.

Once that goal is achieved, Adipogel may be just the ticket for transplanting cells to repair organs.

“You can use this matrix as an adipogenic scaffold for stem cells and transplant it into the body where an organ is damaged. Then, we hope, these cells and the Adipogel can take over and improve their functionality.”