Our tissue's inability to repair itself as we grow older is thought to correlate with the decline in the presence of stem cells. So it follows that if stem cell function can be preserved beyond the norm, it could have implications for the aging process and adverse effects of tissue degeneration, such as cancer. Scientists from the University of Toronto have followed this line of thinking through research on the mammary glands of genetically modified mice, finding that development of the tissue can be manipulated to avoid the effects of aging.

Led by Professor Rama Khoka, the researchers were investigating the relationship between enzymes that break down and then rebuild tissue, and the inhibitors that regulate this process. Known as metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs), how these elements interact can dictate the health of the tissue, and whether it effectively regenerates or begins to deteriorate, possibly leading to cancer.

The researchers worked with mice engineered to be missing at least one of the four different kinds of TIMPs, experimenting with various combinations to observe the impacts on tissue. They discovered that removing TIMP1 and TIMP3 caused the number of stem cells to actually increase and continue to function, resulting in breast tissue that remained young throughout the mice's lives.

"Normally you would see these pools of stem cells, which reach their peak at six months in the mice, start to decline," says Khoka. "As a result, the mammary glands start to degenerate, which increases the risk of breast cancer occurring. However, we found that in these particular mice, the stem cells remained consistently high when we measured them at every stage of life."

Generally, a potential by-product of having a higher amount of stem cells is an increased risk of cancer. However, the researchers say that they found these modified mice to be at no greater risk than normal.

From here, the scientists hope to learn more about this process and establish why removing certain TIMPs impacts aging tissue. Khoka plans to explore how this technique could be used to halt the development of cancer or be adapted as a form of therapeutic treatment.

The team's research appears in the journal Nature Cell Biology.