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Making Good Use of Useless Fat

Scientists transform body fat into bone, cartilage for repair

TUESDAY, Feb. 12, 2002 (HealthDayNews) -- Imagine being able to transform unwanted body fat into bone or cartilage tissue that could repair your body.

Researchers at Duke University Medical Center have achieved this Cinderella effect -- at least in a test tube. They grew functioning cartilage, bone and fat cells from adult stem cells taken from apparently useless fat deposits in an area called the "fat pad" behind the kneecap. This is a potential source of stem cells that avoids the controversy surrounding the use of embryonic stem cells, the scientists say.

Last year, the same research team turned human fat cells salvaged from liposuctions into functioning cartilage cells in mice. Those cells functioned for 12 weeks.

This time around, the scientists went a few steps further.

"We've been able to show [fat pad] cells can be transformed into several different cell types," says Farshid Guilak, senior author of the study and director of orthopedic research at Duke University Medical Center.

Paul R. Sanberg, director of the Center for Aging and Brain Repair at the University of South Florida College of Medicine, says "this is the first study to use the adipose tissue in the knee area, with a concept of creating cartilage to help that knee."

It's also the first time anyone has been able to demonstrate the changes in the fat-derived cells take place at both the genetic and protein levels, says Guilak.

The results were presented this week at the annual meeting of the Orthopaedic Research Society in Dallas.

"Given the enormous pressure being put on embryonic stem cells, adult stem cells are taking on a more and more important role," says Dr. Wise Young, director of the W.M. Keck Center for Collaborative Neuroscience at Rutgers University.

"If adult stem cells prove to be as potent and as efficacious as embryonic stem cells, they will be a cheaper and safer source of stem cells for therapy," he adds.

Most experts believe that stem-cell therapies could help thousands or even millions of people with disorders ranging from diabetes to Alzheimer's disease to multiple sclerosis, Young says.

The fat pad behind the kneecap intrigued the Duke researchers because it has no apparent purpose, and it's different from fat found elsewhere in the body. Although the tissue has no known function, after injury or surgery, it sometimes turns into fibrous tissues, causing the knee to contract and become painful, thus limiting motion. Often, more surgery is required to correct the condition.

"Part of our rationale was, 'What is it about these cells that leads to fibrosis problems in the knee?' " Guilak says. "We're trying to take advantage of that, control the differentiation and have them grow the way we want them to."

The researchers examined fat cells from fat pad tissue that had been removed from patients undergoing total knee replacement surgery. The cells were treated with a series of enzymes and then separated. They were then treated with a combination of steroids and growth factors.

Sure enough, the researchers were able to coax the growth of fat, bone and cartilage cells.

Although humans will not directly benefit from the research for several years, the potential is exciting, researchers say.

"It will likely be at least five years before we can apply this technology to bone and cartilage regeneration. However, for regenerating fat in reconstructive or cosmetic surgery, a clinical application could be possible even sooner," says Guilak. "There are tremendous applications for these cells, if all of this holds out."

Most likely, the first application of this tissue-engineering technology will be to remove fat pad cells from a person, grow them into the cells that person needs, then re-implant them to repair damaged cartilage or bone.

In the future, there may be even more applications.

"Eventually, we'll have the technology to have stem-cell banks," says Guilak. These banks would type-match tissues, and transfer them to another person when needed.

The next step, though, is to try to grow the cells into actual tissues, and implant them in animals to heal a cartilage defect or a broken bone.

It remains to be seen if new discoveries about adult stem cells will fuel or cool the debate about cloning and embryonic stem cells. If so, the real significance of this and related findings could be how they affect academic freedom.

"I would rank [these issues] amongst the top 10 scientific issues of the last 100 years because at stake here is scientific freedom," Young says.

What To Do: Check the National Institutes of Health (NIH) for a for a basic primer on stem cells. For more on the future of stem cell research, check this NIH site.

SOURCES: Interviews with Farshid Guilak, Ph.D., director, orthopedic research, Duke University Medical Center, Durham, N.C.; Wise Young, Ph.D., M.D., director, W.M. Keck Center for Collaborative Neuroscience, Rutgers, the State University of New Jersey, New Brunswick; Paul R. Sanberg, Ph.D., D.Sc., director, Center for Aging and Brain Repair, University of South Florida College of Medicine, Tampa; Feb. 10, 2002, presentation, annual meeting, Orthopaedic Research Society, Dallas
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