Sprouting your own breast tissue

January 23, 2002

By Charlene LainoMSNBC

June 19 — Using high-tech microsurgery techniques and smart scaffolds, tissue engineers have successfully induced the growth of breast and fat tissue in mice and rabbits. Human tests of “natural” breast augmentation could begin within five years, they say.

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THE NOVEL approach, which could one day allow women to sprout their own breast tissue, would offer a natural alternative for those seeking to boost their bust size or undergoing reconstruction after mastectomy for breast cancer, researchers and doctors agree. “This has great potential,” said Dr. Baker, a clinical professor of plastic surgery at the University of South Florida in Tampa. “Using a woman’s own tissue would be ideal, if it works.” Early results indicate the strategy is working. In experiments in mice, both breast and fat tissue were successfully grown inside an implanted chamber filled with a gel that acts like a scaffold, promoting the growth of new blood vessels. And in female rabbits, researchers not only grew a breast-shaped blob of fat tissue in the groin area, but also successfully transplanted the mass onto the chest area. The ultimate goal: To grow realistically shaped breasts directly on a woman’s chest, said Dr. Stefan Hofer, a plastic surgeon and tissue engineer at the Bernard O’Brien Institute of Microbiology in Melbourne, Australia.

The key to success: The continual generation of new blood vessels to nourish the growing tissue in the body. In the past, tissue had to be grown in the lab and transplanted back to the body. “The fact that we’ve grown new tissue — with blood vessels that feed it — right in the body is significant,” said tissue engineer Cronin, who works with Hofer at the O’Brien Institute. Baker agreed. “In the past, when someone tried taking fat from one place and injecting it, you got a lot of cell death, microcalcifications that obscured breast X-rays,” he explained. “But here the tissue is coming in as a living mass that’s vascularized by the new blood vessels. This is smart.” HURDLES REMAIN Nevertheless, many hurdles remain, Cronin said. “First, we’re not even sure it’s desirable to women,” he said. Then, there’s the issue of potential risks. Since the tissue would be a woman’s own, immune-system rejection would not be a problem, but there could be breast cancer risks, Cronin said. If the technique were being performed for reconstructive purposes and microscopic cancerous cells were left behind after mastectomy, those breast cancer cells could start multiplying, he explained. Even if it were done on a woman without a history of breast cancer, there would be the possibility of regenerating cells that contain cancer-making instructions, Cronin said. That’s because cancer is characterized by out-of-control cell growth, and the technique works by inducing cell growth. “So there’s a chance,” he said, “that we could be increasing the chance a woman will get breast cancer — a disease that is very common to begin with — by inducing cell growth.”

Fat tissue that was grown in the shape of a breast in the rabbit's groin area and transplanted looks like the real thing. The blue line marks where the breast was attached to the chest.

For that reason, Hofer said he thinks fat — not breast — tissue is the answer. “There’s no real advantage to using breast tissue, but there is a very real disadvantage in stimulating breast cells that could grow out of control,” he said. “Fat tissue looks just as good and feels just as good. Why not use it?” The major hurdle, Hofer said, is growing enough tissue to fill a chamber the size of the breast the woman desires. “Normal tissue doesn’t just keep growing; only cancer cells do,” he explained. “So the big trick will be to get benign tissue to grow to a certain point and then stop it.” The key, he said, is finding the right combination of special proteins called growth factors. Some of the body’s own growth factors kick in during the wound healing that occurs after the operation to implant the chamber, but these wouldn’t be enough, he said.

The next step in his rabbit tests, he said, will be experimenting with different growth factors to get just the right amount of cell growth. TECHNIQUE OFFERS ADVANTAGES As a doctor who both performs cosmetic surgery on humans and microsurgery on lab animals, Hofer said he has no doubt some women will embrace the technique. While dismissing the possibility that implants cause serious ills like autoimmune diseases — “the research has disproved that” — Hofer said growing one’s own tissue would circumvent long-term problems that are associated with any type of breast implant. First, implants often do not last a lifetime, he noted, so a patient usually has to undergo multiple surgeries, incurring multiple scars. In contrast, tissue engineering requires a small, barely noticeable incision. Second, a new study in this month’s issue of the journal Plastic and Reconstructive Surgery shows that less than half of women who underwent reconstruction of one breast were satisfied with their appearance after five years, he said. The reason: The real breast starts to sag, while the implant remains perky. “If you use your own tissue,” he said, “both would look alike.”

So just how does the procedure work? To grow new breast tissue in mice, Cronin put the lab animal under general anesthesia for an operation in which a silicone chamber is implanted on top of a blood vessel that feeds breast tissue. A biological product known as Matrigel, which acts as a scaffold, is scooped into the chamber, which looks much like a section of electrical cord. Within about 10 days, new blood vessels begin to sprout from that blood vessel and grow into the gel, he said. Then, by two to four weeks, breast cells begin to migrate into the area of the gel where they are nourished by the new blood vessels. During this time, proteins known as growth factors are released into the gel as a result of wound healing from the operation. Once the breast cells have established themselves, they start to produce collagen that forms a scaffold of its own. The Matrigel, which is biodegradable, breaks down and disintegrates. Breast cells continue to grow in the area of the gel until they form a mass of breast tissue the size and shape of the silicone chamber. The chamber can then be removed during another simple operation; ultimately, researchers said it, too, will be made of a biodegradable material. GROWING A RABBIT BREAST Hofer’s rabbit experiments went a step further, and utilized fat rather than breast tissue. Since the tissue appears to grow in the shape of the chamber that is originally implanted, he used a droplet-shaped chamber that is more anatomically correct for a breast. And for the scaffold, he chose a biomaterial known as polyglycolic acid, a white porous sponge that provides more stability than the gel for the blood vessel growth and contains some growth factors. The final product — a breast shaped mass of fat tissue — was transplanted into the chest of the rabbit.

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Growing the natural transplants took a few months; in humans, it could take six months to grow a breast, Hofer said. “But breasts aren’t all we will be able to grow,” he predicted. “In fact, even more popular will be growing smaller amounts of tissue for contour effects — filling in scars or smoothing wrinkles, for example. That could happen within two years.” And while the scaffold materials used thus far seem to have a predilection for fat or breast cells, other tissue engineering techniques could help build all sorts of spare body parts — from livers to hearts, Cronin said. “The potential is huge.” Return next Monday for Skin Deep Part 4: Beauty in a syringe.

Novel wrinkle fillers in the pipeline

4 of 4

1. Back-alley beauty injections

2. A return to silicone valley?

3. Sprouting new breast tissue

4. Novel wrinkle fillers in the pipeline

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