‘Super exciting’ results in stem cell therapy trial

Scientists Kuldeep Kaur (left), Peter Llontop and Heather Jones work together on stem cell research at Asterias Biotherapeutics in Fremont, which had striking results in a recent trial. Scientists Kuldeep Kaur (left), Peter Llontop and Heather Jones work together on stem cell research at Asterias Biotherapeutics in Fremont, which had striking results in a recent trial. Photo: Gabrielle Lurie, The Chronicle Buy photo Photo: Gabrielle Lurie, The Chronicle Image 1 of / 5 Caption Close ‘Super exciting’ results in stem cell therapy trial 1 / 5 Back to Gallery

Four out of six paralyzed patients who had 10 million stem cells transplanted into their spinal cords have shown striking improvement a year after treatment, including increased ability to move their hands and arms and to perform basic functions like feeding and bathing themselves, according to research results being released Monday.

All six patients in the early-stage clinical trial, conducted by Fremont’s Asterias Biotherapeutics, reported at least some recovery after the stem cell transplant. The trial is among the first to use embryonic stem cells in human subjects.

It’s too soon to know for sure that the stem cells were solely responsible for the patients’ improvement. The patients could have experienced a spontaneous recovery, which is not unheard of in spinal cord injury victims, or their improvement could be the result of intense rehabilitation.

But compared to a large group of people with similar injuries, the results among patients treated with stem cells were remarkable, said doctors and scientists involved with research.

“Scientifically, I have to say we don’t know for sure if it’s the stem cells. But I’ve been treating these kinds of patients for 30 years, and I’ve never seen anything like this before,” said Dr. Richard Fessler, lead investigator of the Asterias trial and a professor in the department of neurosurgery at Rush University Medical Center in Chicago.

There are no FDA-approved treatments for spinal cord injuries, and currently patients can only improve with rehabilitation, Fessler said. “This is the first time we’ve had reason for hope,” he said.

The Asterias treatment uses embryonic stem cells that have been expanded from cells first isolated in the 1990s, from an embryo that had been made for in vitro fertilization and was later donated for scientific research. Scientists at Asterias’ Fremont laboratories process the stem cells to turn them into cells called oligodendrocyte precursors, which are then transplanted directly into the spinal cord with a syringe.

Oligodendrocytes are support cells that are largely responsible for building the insulation material, called myelin, that keeps nerve cells healthy and functional. In spinal cord injuries, many nerve cells are killed outright, and often the myelin on remaining cells is damaged beyond the body’s ability to repair naturally.

Without myelin, nerve cells are unable to send signals up and down the spine to control movement or sensory information in the limbs and other parts of the body. People who have suffered the most serious spinal cord injuries will not be able to move or feel anything below the point of injury.

The Asterias therapy is believed to boost healing. Studies in animals showed that the transplanted cells can repair myelin on their own, as well as release chemical agents that trigger the body to repair itself.

Earlier versions of the Asterias study — which were conducted by a Menlo Park company called Geron Corp. that later passed on the spinal cord injury research — transplanted 2 million cells into patients. That was considered a large enough amount to test whether the transplant was safe, but too small to actually help patients recover.

The newer study transplanted 10 million cells, enough to have a therapeutic effect. Another study that’s still enrolling patients is transplanting 20 million cells. All patients are treated within a month or two of their injury, which is considered the optimal time to promote healing, before scar tissue begins to develop.

According to the results released Monday, 67 percent of patients — or four out of six — in the 10-million-cell study had improved by at least two motor levels in the 12 months since they were treated. In control groups made up of patients with similar injuries, 26 to 29 percent experienced two motor levels of improvement.

The patients are by no means fully recovered. But two motor levels generally means they had much better use of their hands and arms. A patient who improves two levels could go from not being able to help a caretaker dress him to being able to mostly dress himself.

That the patients were still improving a year from the transplant suggested that the stem cells were still healthy and functioning — something scientists weren’t sure would happen.

“The bottom line is super, super exciting. Well beyond anything I thought we could have achieved at this point,” said Dr. Edward Wirth, chief medical officer with Asterias.

Christopher Block, 31, couldn’t lift his left arm at all and could barely raise his right arm to his chest in the first weeks after he suffered a spinal cord injury in a bicycle accident near his home in Lake Forest, Ill., in July 2016.

“About a month after my stem cells, I was able to begin feeding myself,” Block said. He could raise his right arm to his face, and lift his left arm a few inches off the bed.

Now more than a year after the August 2016 treatment, Block is able to get himself out of his wheelchair and change his shirts. He’s been working out and hopes to be driving and living largely independently in another year or so.

“I’m excited to be on the forefront of science,” Block said. “I’m happy to be a guinea pig.”

The next step in clinical research will be conducting a randomized controlled trial, which would compare patients receiving stem cell transplants to a group getting exactly the same care without stem cells. Wirth cautioned that though the new results are thrilling, it’s not uncommon for therapies to prove less effective when tested under more rigorous conditions.

“We have sufficient confidence that we’re ready for a randomized controlled trial,” Wirth said. “What we really need now is to put our therapy to the test. If it holds up, then we’ll be on track for (FDA) approval.”

Asterias also announced Monday that the U.S. Food and Drug Administration had granted the company’s request for a special designation that is meant to speed up the research and approval process for stem cell therapies. The Regenerative Medicine and Advanced Therapy designation, which only went live this year and has been granted to five or six companies, doesn’t guarantee FDA approval, but it implies that Asterias has a strong record so far.

The Asterias trials have been funded in part by a $14 million grant from the California Institute for Regenerative Medicine, the state’s stem cell agency.

Erin Allday is a San Francisco Chronicle staff writer. Email: eallday@sfchronicle.com Twitter: @erinallday