Lab Mice Shed Fat and Build Muscle with Gene Therapy

body composition in lab mice drastically improved

By Jonny Lupsha, Wondrium Staff Writer

Researchers injected genes into mice that caused them to lose weight and gain muscle, Fierce Biotech reported. The treatment may one day help people who are reluctant or unable to exercise to get into better shape. Gene therapy can also treat or cure diseases.

Lab concept, genes in dish
Gene therapy, or genetic engineering, involves making local modifications to the human genome for the purpose of therapeutic therapy in treating disease. Photo by Igor Stramyk / Shutterstock

According to the Fierce Biotech article, the mice who underwent the new gene therapy were injected with a gene that makes the protein follistatin, which in turn blocks a protein called myostatin. Myostatin regulates muscle growth. “The therapy caused a significant buildup of muscle mass in the mice while also preventing obesity,” the article said. “The mice didn’t just build muscle; they also nearly doubled their strength without exercising any more than they usually did. Despite being fed a high-fat diet, they had fewer metabolic issues and stronger hearts than did animals that did not receive the follistatin gene.”

Scientists have been developing gene therapy for many years. It can change our bodies in many ways, and has potential serving as a treatment for cancer and muscular dystrophy.

Understanding Gene Therapy

The procedure that the mice underwent encapsulates what gene therapy is—although scientists generally focus on people.

“I define [gene therapy] as the addition of genes to humans for medical purposes,” said Dr. David Sadava, Adjunct Professor of Cancer Cell Biology at the City of Hope Medical Center.

Dr. Sadava said gene therapy is based on four assumptions. First, whoever is doing the gene therapy has to know the gene that’s involved in whichever problem needs to be treated. Second, they must have a normal, healthy copy of that gene available in the lab. Third, they must know where and when the gene is normally expressed. Finally, they have to be fairly certain what will happen when the gene is expressed normally.

Additionally, gene therapy must do several things in order to be considered successful.

“First, gene therapy must get the gene into the appropriate cells,” Dr. Sadava said. “Second, gene therapy must get the gene expressed in those cells. Third, we have to get the gene integrated into the genome of the target cells so it’ll be there permanently. And fourth, you better not have any bad side effects to gene therapy, like any therapy in medicine.”

Practical Applications of Gene Therapy

According to Dr. Sadava, one kind of gene therapy is referred to as gene augmentation, and it comes into play when the functional product of a gene has been lost and no longer gets produced normally. By injecting a gene into someone, healthy copies of a protein product will be made and function restored.

“We could hypothetically think of muscular dystrophy as a good target for gene therapy,” he said. “We know that muscles lack the protein dystrophin—it’s an organizing protein—so we’ll put in the good gene for good dystrophin.”

Another kind of gene therapy is called target cell killing. Dr. Sadava said it uses a gene that either produces a poison that kills certain types of cells or it stimulates the immune system to do so. Target cell killing can be applied to cancer.

“A gene is put into cancer cells that allows them to produce a protein that will make a toxic drug from a harmless chemical,” Dr. Sadava said. “So the idea is we inject a harmless chemical into the body, it goes all over the body and when it enters a tumor cell, it’s converted into a poison by the gene product of the gene that we’ve put in for gene therapy. So we might put in a gene that will cause a protein to be made that attracts killer T cells so the tumor will stick up its hand and say ‘Come kill me now.'”

Gene therapy is an exciting field in science and medicine with a lot of potential for humans. For now, it may seem like it’s just helping some overweight mice get a confidence boost, but the practical applications should shore up within our lifetime.

Dr. David Sadava, Ph.D.

Dr. David Sadava contributed to this article. Dr. Sadava is Adjunct Professor of Cancer Cell Biology at the City of Hope Medical Center in Duarte, CA, and the Pritzker Family Foundation Professor of Biology, Emeritus, at The Claremont Colleges. Professor Sadava graduated from Carleton University with a B.S. with first-class honors in biology and chemistry. He earned a Ph.D. in Biology from the University of California, San Diego.