Researchers have used a new microscopic, three-dimensional scaffolding to coax mouse stem cells to transform themselves into fat cells, and then to function identically to how fat cells naturally do in the body. This discovery offers hope of a new approach to growing fat tissue for use in breast reconstruction surgery and other clinical needs, and may even be important for curing type II diabetes.

Douglas Kniss, professor of obstetrics and gynecology and of biomedical engineering at Ohio State University, reported this progress in the journal Tissue Engineering.

While other studies have previously grown fat cells, or adipocytes, in the laboratory, those cells never completely functioned in the same way they do in normal tissue. They failed to produce the genetic and biologic components that all cells require to do their work.

Along with Xihai Kang and Yubing Xie, both postdoctoral fellows in his laboratory, Kniss built a fabric-like carpet of polyethylene terephathalene (PET), or Dacron, fibers that served as scaffolding upon which new fat cells were grown.

In conventional cell cultures, cells usually grow as flat deposits bathed in growth medium. While useful, these "two-dimensional" patches fail to mimic all the tasks performed by cells in vivo. Specific genes, proteins and hormones normally produced by healthy cells are often absent in two-dimensional colonies.

"The PET fibers are spun out onto a mat that resembles the intracellular matrix that bonds cells together in normal tissue. The fibers are about the size of a collagen fiber, several nanometers (a billionth of a meter) across, and provide tensile strength to support the growing tissue," Kniss said.

The researchers then "seeded" that scaffolding with cells called pre-adipocytes cells that had begun their transformation from stem cells. "They just needed to be tweaked with a cocktail of hormones for them to evolve into fat cells," he said.

Kniss said that the transformation into bona fide fat cells took about two weeks to complete. At that point, the cells were able to absorb lipids, a hallmark task of fat cells.

Researchers were able to extract RNA from the cells, just as they can from naturally occurring fat cells, and from that proved that the cells expressed the normally expected array of genes and subsequent proteins that occur in normal tissue.

SOURCES:
Tissue Engineering, March 2005
Ohio State University (http://www.osu.edu)