Gordie suffered two strokes late last year and had "maybe a month to live," Marty said, when his family took the 86-year-old to Mexico in December for the treatment.
Gordie Howe can walk again, his speech is improving and he's gained weight that he lost, according to his son.
"He is doing so much better," Marty said Tuesday in Calgary. "It's a joy to have him with us still.
"Hopefully, in my mind, we're going to have another treatment of this probably within two months.
"I'm actually hoping if he keeps doing what he's doing he'll be able to travel again and maybe get to five or six events a year so people can see him another time."
Gordie Howe, known as "Mr. Hockey", holds NHL records for most games played (1,767) and seasons played (26). He won the Stanley Cup four times as a Detroit Red Wing and also played for the Hartford Whalers.
His 801 career goals rank second only to Wayne Gretzky's 894.
Gordie Howe and Gretzky are scheduled to appear Feb. 6 in Saskatoon at a dinner, which Marty said will be a "trial run" on how his father responds to travel.
Marty Howe was in Calgary alongside NHL alumni Darryl Sittler, Marty McSorley and Lanny McDonald to promote a pro-am hockey tournament in Gordie's name that raises money for Alzheimer's and dementia research.
The April 17-19 tournament is in its fifth year and has raised a total of $1.5 million, according to organizers. Gordie became involved with dementia research because his wife Colleen died in 2009 of Pick's disease, which is a form of dementia.
Gordie is now also affected by dementia, which Marty does not expect to change with stem cell treatment.
"He still has dementia," Marty said. "It's not a cure, but it sure prolongs life and the quality of life that you have is greatly increased."
Gordie is in Lubbock, Texas, with his daughter Cathy Purnell. What appeared to be a setback after his return from Mexico was caused by dehydration, said Marty.
"The biggest thing was his swallowing," he said. "With dementia, your brain forgets how to do it. That's where he was.
"He had lost so much weight. He was down to 175 pounds. The Gordie Howe that everyone is used to, he didn't look like Gordie Howe. He was starting to fade away."
The family was contacted by Stemedica Cell Technologies in San Diego, Calif., about treating Gordie in a stem cell clinical trial. The treatment is not yet approved in the United States.
The family made the difficult decision to fly their ailing father to San Diego and drive him to Mexico.
"We were told to have the hospice come in and take care of his meds and everything and just let him go peacefully and we just weren't ready," Marty recalled.
"Every once in a while you could see in his eyes that there was something in there still that was Gordie that wanted to get out. We wanted to give him the chance."
The family has described the treatment as neural stem cells injected into the spinal canal, as well as mesenchymal stem cells administered by intravenous infusion.
Researchers caution that most stem cell therapies are experimental and have not been approved by government regulators in Canada or the U.S. The International Society for Stem Cell Research, a leading professional group, has issued a guide for patients and their families advising them to approach stem-cell therapy with extreme caution.
Marty pointed out Tuesday the procedure involves adult, not embryonic, stem cells.
"As a longshot it seemed to us at the time, it was worth it," he said. "We took him down there and the results were pretty unbelievable.
"He went from not being able to walk to getting the stem cell treatment and was able to walk that day, not very well mind you but he was moving his feet.
"Going back on the plane on the way back, he was able to walk on the plane to his seat. It's unbelievable."