Scientists have converted human skin cells into brain cells and used them to treat mice with myelin disorders, a family of diseases that includes multiple sclerosis.

The research, reported Thursday, marks another promising advance for a technique known as cell reprogramming. The approach returns mature cells to an embryonic-like state, and then transforms them into various types of fresh, healthy tissue that could be used to treat diseases.

Multiple sclerosis is the most common myelin disorder. It strikes when the body's own immune system attacks myelin, the coating around nerve fibers. That disrupts communication between cells and can cause problems related to muscle movement, balance and vision.

In the latest study, the reprogramming technique "led to the re-myelination of the complete nervous system" of diseased animals, improving their symptoms and prolonging their life, said Steven Goldman, lead author of the report and a neurologist at University of Rochester Medical Center in Rochester, N.Y.

The findings appear in the journal Cell Stem Cell.

Myelin is made in cells known as oligodendrocytes. Those, in turn, are the offspring of oligodendrocyte progenitor cells, or OPCs.

One way to tackle a malady like multiple sclerosis is to transplant healthy, lab-made OPCs into the diseased brain, which could restore the lost myelin and reverse the damage from the disease.

Dr. Goldman's team first reprogrammed human skin cells into embryonic-like stem cells. Then they identified the cascade of chemical signals used by the body to turn embryonic cells into OPCs—and replicated that process in a lab dish.

It was hard to do, mainly because OPCs form very late in the body's development, via a multistage and complex process. It took the researchers six years to decipher the signals and to produce and purify enough OPCs that would yield sufficient myelin.

The OPCs were transplanted into mice with leukodystrophy, a hereditary condition that rendered them incapable of producing myelin. (Each year, thousands of children are born in the U.S. with some form of leukodystrophy.)

In the experiment, untreated mice displayed the typical symptoms of myelin-loss as they grew older: They developed tremors, lost their sense of balance and died prematurely, often from seizures.

The treated group initially also developed tremors and other symptoms. But once the transplanted cells began to produce sufficient myelin—it took four months—their symptoms improved and they no longer died of seizures.

Dr. Goldman said he hopes to start human trials using the cell-transplantation approach in 2015.

Write to Gautam Naik at