The majority of the millions of plastic surgeries performed in the U.S. each year aren’t cosmetic procedures for Hollywood starlets or Beverly Hills housewives trying to hold on to their youthful looks. They’re reconstructive operations for patients with disfiguring injuries, tumor resections and congenital defects such as childhood hemangiomas, which can occur on the face.
A big challenge in reconstruction is compensating for the loss of a large volume of subcutaneous fat. Currently, there are three ways to do this, none of them ideal.
One method uses fillers like collagen gels to augment soft tissue, but the body rapidly degrades them. Another method is fat grafting: the patient’s own fat cells, obtained by liposuction, are re-injected at the desired site. But the implanted tissue doesn’t engraft well and doesn’t survive long, mainly because it doesn’t develop an adequate blood supply. A third method uses synthetic materials, such as silicone implants, but these don’t integrate into the patient’s surrounding tissue and present a risk of rupture, leakage or dislocation.
Juan Melero-Martin, in the Department of Cardiac Surgery at Children’s Hospital Boston, is taking a different approach. With his former mentor Joyce Bischoff of Children’s Vascular Biology Program, he’s seeking to engineer fat tissue with its own blood supply, using the body’s own regenerative capacity.
Although his work is still at an early stage, using human cells in mouse models, it has the potential to combine the best of the current approaches. He envisions it working like this:
1) A mix of progenitor cells, able to form adipocytes (fat cells) and a vascular network, would be purified from the patient’s own blood and fat. They would then be propagated in a dish, combined with an appropriate gel and injected at the desired site under the patient’s skin.
2) The implanted cells then create networks of blood vessels that connect to the patient’s own vascular system, allowing blood perfusion through the tissue.
3) Some of the cells then differentiate into fat tissue, by mimicking the patient’s own surrounding subcutaneous adipose tissue.
The blood supply and fat tissue would develop naturally in the patient’s body. Melero-Martin expects this technology to have better longevity than current collagen-type fillers, since the gel in this case is loaded with the patient’s own progenitor cells. As the gel is degraded, it would be progressively replaced by a permanent subcutaneous fat pad.
Three years ago, with U.S. Army funding, Melero-Martin and Bischoff were the first to grow functional human blood vessels in mice using human progenitor cells – a big step forward in tissue engineering. Melero-Martin noticed that fat tissue appeared after the vascular network was established. Based on this fortuitous scientific observation, the project on engineering vascularized adipose tissue was born.
“Additional work needs to be done to further develop this cell-based approach,” he says. “For example, we are looking into ways that we can accelerate generation of the new fat tissue, but we are hopeful that it could represent a novel option in reconstructive surgery.”
A closing note for Hollywood starlets and Beverly Hills housewives: Yes, this new technology could also be applied to cosmetic procedures such as lip augmentation and wrinkle correction.