Scientists in Michigan have discovered a biological mechanism that can preserve the gastrointestinal tracts of mice after a lethal dose of chemotherapy, a discovery that could lead to better tolerance of chemotherapy in humans with later stage cancer.

High doses of chemotherapy and radiation can kill all tumours from different tissues and organs, but for later stage cancer, due to the harmful effect chemotherapy has on the body, there is a risk you can actually kill the patient with the chemotherapy.

However, if the gastrointestinal tract remains healthy and functioning, the chances of survival increase exponentially, said University of Michigan School of Dentistry associate professor Jian-Guo Geng who helped conduct the study.

"Years down the road, we may have a way to make humans tolerate lethal doses of chemotherapy and radiotherapy," he added.

"In this way, the later-staged, metastasized cancer can be eradicated by increased doses of chemotherapy and radiation."

In the study, 50%-75% of the mice treated with the molecule survived otherwise lethal doses of chemotherapy. All of the mice that did not receive the molecule died.

The scientists found that when certain proteins bind with a specific molecule on intestinal stem cells, it pushes intestinal stem cells into overdrive for intestinal regeneration and repair in mice.

Stem cells naturally heal damaged organs and tissues, but so-called 'normal' amounts of stem cells in the intestine simply cannot keep up with the wreckage left behind by the lethal doses of chemotherapy and radiation required to successfully treat late-stage tumours.

However, extra stem cells can protect the intestines and gastrointestinal tract, which allows the ingestion of nutrients so the body can perform other critical functions and the bacterial toxins in the intestine are prevented from entering the blood circulation.

Geng's lab has worked with these molecules, called R-spondin1 and Slit2, for more than a decade.

Geng has stressed that even if they do conduct human trials and they show promise, it could take a decade or longer before an application becomes available to use on people.

"Now we have found a way to protect the intestine in mice," Geng added. "The next step is to aim for a 100% survival rate in mice who are injected with the molecules and receive lethal doses of chemotherapy and radiation."

The study, 'Induction of intestinal stem cells by R-spondin 1 and Slit2 augments chemoradioprotection', is published now in Nature Journal.