(CBS) — New parents are given the option to store their child's umbilical cord stem cells. They can be seen as a "repair kit" for the body. A couple in Sacramento says the cells changed their child's life.

Excited over their first born, it didn't take long for Cynthia and Derek Hextell to suspect something was wrong with baby Dallas.

"He didn't open his eyes,” Cynthia said. “He just cried constantly, and they kept saying it was colic.”

At 8 months old, Dallas was diagnosed with cerebral palsy. There is no cure for the brain damage — only medication and therapy to help manage the debilitating effects.

"You can tell he's frustrated because his mind is healthy and he wants to do things physically,” Cynthia said. “He just can't."

By the time Dallas reached 18 months, his only form of communication was screaming. He also lacked control over his body, unable to clap, wave, crawl or speak.

Conventional therapy had little impact.

But when Dallas was born, his parents decided to bank his stem cells. These are not the controversial stem cells created from embryos, but those taken directly from the umbilical cord.

Dallas was accepted into a clinical trial at Duke University. By placing his own stem cells back into his body through a simple IV, doctors hoped the cells would heal the damaged part of his brain.

"The hope is that the infusion of these cells would lessen the severity of cerebral palsy in these children,” explained Duke University’s Joanne Kurtzburg.

Insurance did not cover the $12,000 for the experimental treatment. Following the procedure, Dallas was brought back to Sacramento, the family waiting to see if the cost and their efforts would pay off. They didn’t have to wait long.

Incredibly, just five days later, Dallas spoke for the first time. He also learned to wave.

“That's the best feeling in the world, to hear your little kid laugh,” Derek said. “He never laughed before.”

There is no way to know if or how much the improvements are directly related to the treatment. But Dallas, just three months later, is on the move, with muscle control, and his own way of getting around.

"When you talk to him he looks at you and listens to you,” Derek said.