A study by researchers at Stanford's School of Medicine has revealed that fat that is left after liposuction is a huge bank of versatile cells that could be more quickly and easily coaxed to become induced pluripotent stem (iPS) cells than the often used skin cells.
Lead researcher Dr. Michael Longaker has even called the readily available liposuction leftovers "liquid gold".
"We've identified a great natural resource," said Longaker.
Reprogramming adult cells to function like embryonic stem cells is one way the researchers hope to create patient-specific cell lines to regenerate tissue or to study specific diseases in the laboratory.
"Thirty to 40 percent of adults in this country are obese. Not only can we start with a lot of cells, we can reprogram them much more efficiently. Fibroblasts, or skin cells, must be grown in the lab for three weeks or more before they can be reprogrammed. But these stem cells from fat are ready to go right away," said cardiologist Dr. Joseph Wu.
As the cells can also be converted without the need for mouse-derived "feeder cells", they could be an ideal starting material for human therapies.
The flab, which is left post liposuction, is filled with multipotent cells called adipose, or fat, stem cells.
Unlike highly specialized skin-cell fibroblasts, these cells have a relatively wide portfolio of differentiation options-becoming fat, bone or muscle as needed.
The researchers believe that it is this pre-existing flexibility that gives these cells an edge over the skin cells.
"These cells are not as far along on the differentiation pathway, so they're easier to back up to an earlier state. They are more embryonic-like than fibroblasts, which take more effort to reprogram," said first author Dr. Ning Sun.
These reprogrammed iPS cells are usually created by expressing four genes, called Yamanaka factors, normally unexpressed (or expressed at very low levels) in adult cells.
The researchers found that the fat stem cells actually express higher starting levels of two of the four reprogramming genes than do adult skin cells, which indicated that these cells are already primed for change.
After adding all four genes, about 0.01 percent of the skin-cell fibroblasts eventually became iPS cells but about 0.2 percent of the fat stem cells did so-a 20-fold improvement in efficiency.
The new iPS cells passed the standard tests for pluripotency.
"The idea of reprogramming a cell from your body to become anything your body needs is very exciting," said Longaker
The findings have been published in the Proceedings of the National Academy of Sciences.