Researchers at Wake Forest University School of Medicine have successfully isolated stem cells from human skin, expanded them in the laboratory and coaxed them into becoming fat, muscle and bone cells. The study, one of the first studies to show the ability of a single adult stem cell to become multiple tissue types, is reported today in Stem Cells and Development.
"These cells should provide a valuable resource for tissue repair and for organs as well," said Anthony Atala, M.D., director of the Wake Forest Institute for Regenerative Medicine and senior researcher on the project. "Because these cells are taken from a patient's own skin, there would not be problems with organ or tissue rejection."
The research team grew mesenchymal stem cells, a type of stem cell normally found in bone marrow. Using tissue samples from 15 donors who had routine circumcisions, the scientists were able to isolate single stem cells, which they then grew in culture dishes in the laboratory. The scientists used hormones and growth factors to coax the stem cells into becoming fat, muscle and bone cells.
When the differentiated cells were seeded onto three-dimensional molds and implanted in mice, they maintained features consistent with bone, muscle and fat tissue. "Our study shows that stem cells can be obtained from a simple skin biopsy and can be made to become three vital tissues," said Shay Soker, Ph.D., associate professor of surgery at Wake Forest's School of Medicine, which is part of Wake Forest University Baptist Medical Center. "The bulk of our bodies is made up of fat, muscle and bone."
The promise of stem cells lies in their ability to develop into specialized types of cells and to replicate themselves. Scientists hope to harness the potential of stem cells and use them to replace damaged cells and tissue in conditions such as spinal cord injuries, diabetes, Alzheimer's disease, stroke and burns.
Most scientists believe that stem cells from human embryos are the most versatile type of stem cell because they have the potential to form any cell or tissue in the body. But they are also exploring the potential of stem cells from adults. In addition to skin, the cells have been identified in bone marrow, the brain and blood from the umbilical cord.
"Compared to bone marrow, a skin biopsy is easy to take, so it offers advantages for clinical use," said Soker. "The cells can be obtained from any small sample of human skin."
Next, Atala's research team hopes to test the function of the tissue that was created from the stem cells.
"We've proved that the cells can be used to engineer tissues consistent with bone, muscle and fat when implanted in animals; now we need to test their function long term," said Soker.
Soker said the cells have potential to be used both in tissue engineering – the science of growing tissues and organs in the laboratory – as well as in cell therapy. For cell therapy, laboratory-grown cells would be injected into the body to replace breast tissue removed by surgery, to fill in the gaps in bone fractures or replace muscle damaged by injury.
"The ability to engineer tissues from a patient's own cells may overcome two major problems in transplantation medicine: immune rejection and tissue shortage," Atala said.