Stem cell therapy restores muscle function in mice with muscular dystrophy

Jan 21 2008

Scientists in Texas have been able to restore muscle function in mice with muscular dystrophy by using embryonic stem cells.

Muscular dystrophy is a genetic disease that occurs when the cells can no longer regenerate after injury and there is no effective treatment for the disease.

The muscle-wasting conditions are caused by genetic mutations which block production of a key structural protein of muscle cells called dystrophin, resulting in progressive muscle weakness and eventually death.

The mice used in the study were genetically engineered to have Duchenne muscular dystrophy, the most common form of muscular dystrophy in children and the therapy used embryonic stem cells.

The researchers say their study is the first to show that transplanted embryonic stem cells can restore muscle in genetically engineered mice with the disease.

Stem cells which are the body's master cells, are a source for the various cells and tissues in the body and those taken from days-old embryos, called embryonic stem cells, can produce all of the body's cell types.

Other researchers have experimented with different stem cell strategies in the hope of treating the devastating disease but results have often been disappointing because embryonic stem cells, as they can form all the tissues in the body, often form tumours called teratomas.

Enabling them to become only certain cell types has been difficult and Dr. Rita Perlingeiro of the University of Texas Southwestern Medical Center, says a method had to be found to extract the cells they wanted.

Perlingeiro's team experimented with stem cells taken from mouse embryos; the mice in the study lacked dystrophin, a protein that is lacking in humans with muscular dystrophy.

Perlingeiro's team developed a painstaking technique using fluorescent dyes to sort through the cells, allowing them to isolate only the cells destined to become muscle.

They then injected these cells into the hindquarters of mice with the disease and within a month, the dyed cells had made their way deep into the muscle, suggesting they had started to grow new muscle cells.

By three months, the mice showed no signs of tumours and tests showed the muscles were significantly stronger than in untreated mice with the condition, and their performance in tests of coordination was also better.

The researchers hope to eventually develop a stem-cell therapy for humans with muscular dystrophy using a new approach for making human stem cells from reprogrammed skin cells.

This approach will involve tricking human skin cells into behaving as embryonic stem cells but the researchers say the technique is, as yet, far from perfected.

Duchenne muscular dystrophy is one of nine types of muscular dystrophy, a group of degenerative diseases; symptoms usually appear in male children before age 6 and the condition is terminal with death usually occurring before the age of 30.

Genetic counseling is advised for people with a family history of Duchenne muscular dystrophy which can be detected with about 95% accuracy by genetic studies performed during pregnancy.

Duchenne muscular dystrophy occurs in approximately 2 out of 10,000 people and can either be inherited or occur spontaneously; a family history of Duchenne muscular dystrophy is a significant risk factor.