BEVERLY HILLS, Calif. — More than 170 clinics across the country are selling experimental stem cell procedures for dozens of diseases and conditions — a mushrooming industry that has flourished despite little evidence of its safety or effectiveness.

The rise of the U.S. stem cell industry illustrates how quickly fringe medicine can outpace government oversight. Over the last five years, academic stem cell researchers have watched in dismay as doctors treat patients with experimental techniques that they say could take years, if not decades, to become sound medicine.

Clinics throughout the country promote stem cells for dozens of conditions and diseases, including Alzheimer’s, arthritis, erectile dysfunction and hair loss. The cost of these procedures ranges from $5,000 to $20,000.

Many of the businesses are linked in large, for-profit chains.

The largest of these chains is the Cell Surgical Network, co-founded in 2012 by Dr. Mark Berman, who spent 30 years as a Beverly Hills plastic surgeon before working with stem cells. His company offers stem cell procedures for more than 30 diseases and conditions, including Lou Gehrig’s disease, multiple sclerosis and arthritis. He and his partner adapted technology from Asia into a liposuction-based procedure in which fat is pumped out of patients’ abdomen, processed with drugs and then injected back into the body.

Berman says this fat-based “soup,” is rich in shape-shifting stem cells that have the potential to treat everything from neurological diseases to achy joints.

“I don’t even know what’s in the soup,” says Berman. “Most of the time, if stem cells are in the soup, then the patient’s got a good chance of getting better.”