If it weren't for a stem cell transplant — less than half a cup of blood from a stranger's umbilical cord — four-year-old Tristan Ford would almost certainly have died as an infant, his parents say.

Now, he's smaller than other kids his age. But in almost every other way, he's a normal kid.

Ford suffers from Griscelli syndrome, an inherited condition that could cause severe problems with brain function or the immune system. It's one of the 80 conditions, ranging from blood cancers, blood disorders, immune disorders and metabolic disorders, that doctors currently treat with a stem cell transplant from cord blood.

Umbilical cord blood is a rich source of stem cells. They're more flexible: because a baby's immune system is less mature, their stem cells can successfully be transplanted to patients, even if the cells don't perfectly match. In Tristan's case, doctors had to give him an intense round of chemotherapy to wipe out his errant immune system entirely, before transplanting the cord blood, which started producing its own healthy cells.

It's a rare story. Almost a decade after the creation of a national public cord blood bank, latest data shows its use remains infrequent.

Of nearly 4,700 units banked, only 86 have been used. Twenty-eight were sent to patients in Canada, while 58 were sent to international patients, according to Canadian Blood Services. Canadian patients also received 181 samples from international donors, said the non-profit organization. Canadian Blood Services says it cost $48 million to establish the national public bank. Provincial and territorial governments (except Quebec) contributed to the investment, and Canadian Blood Services fundraised $12.5 million.

"Low numbers doesn't equate to low importance," said Dr. Matthew Seftel, the medical director of stem cells at Canadian Blood Services.

"They fulfill a niche for patients who are particularly hard to serve, that are particularly hard to find matches for."

While recipients who need cord blood from the public bank aren't charged, that's not the case for a host of private cord blood banks, which promise the future use of the stem cells — even when many potential treatments are still at experimental stages.

WATCH | Why cord blood transplant numbers are low despite donations:

Media Video | The National : Cord blood transplants remain rare but life-saving

Caption: New data from the Canadian Blood Services' Cord Blood Bank show less than two per cent of donated units have been transplanted in nearly a decade. The treatment is still rare, but scientists say it's important for saving the lives of young patients who are hard to find stem cell matches for.

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Seftel says there are several reasons why cord blood transplants are relatively rare. For one, umbilical cords just don't have a lot of blood: a little less than half a cup, in most cases. That's enough for kids – but not for most adults.

"It's wonderful for many children who don't need many cells, but the largest amount of demand for transplantation globally is in adults."

Advances in treating certain cancers like leukemia are also why cord blood is not being used more often, says John Dick, a senior scientist at Princess Margaret Cancer Centre in Toronto. For instance, he says, CAR T-cell therapy, which engineers patients' immune cells to help treat their cancer, was not available 10 years ago.

"There are a whole number of other therapies that have come forward where you really target the specific abnormalities of the cancer."

Nonetheless, Dick sees the need for a public cord blood bank.

"Cancer can be a wily beast, and sometimes it can escape the best of therapies. And then this becomes the only rescue that's left for you."

Especially, he says, because the Canadian public bank is so diverse.

A 2022 analysis of cord blood usage from Canadian Blood Services' public bank found stem cells from multiethnic donors made up a significant part of the units that were distributed. Nearly half the units distributed were from non-Caucasian donors.

Parents also have the option to bank their child's cord blood privately, for roughly $1,000 up front, and yearly fees of hundreds of dollars. But in the private system, where families would be able to save the sample for their personal use only, cord blood transplants may be even rarer, according to numbers from one private cord bank.

"Of the 50,000 units or so, we have only released fewer than 10," says Edmond Wong, a scientific director at Healthcord Cryogenics, one of a handful of companies that operate private cord blood banks in Canada.

That's because in most cases, a child who gets sick with a condition treatable with cord blood can't use their own sample.

"I absolutely do not want to use those stem cells," says Dick. "If my child has leukemia, that leukemia started when the baby was still in the uterus."

Private companies say they're selling a promise — that these cord cells would be useful in the future, if and when there are breakthroughs in science. Several private banks advertise a lot of potential uses for cord blood cells, like for Alzheimer's, autism and diabetes, saying they are still experimental.

"The expectation is that they are for future use, so it's sort of like an insurance in a sense," Wong said, saying the cord blood can be stored for decades.

Those are promises some say the science can't back up yet.

"They play on the hype around stem cells, not on the reality," says Tim Caulfield, a law professor at the University of Alberta's school of public health.

"I think they over-promise, at least implicitly, about how often or how likely you are to use these therapies. And I think they also play on parental guilt and fears."

Private banks also have the potential to "take donors away from public banks where there is a higher likelihood of use," says Caulfield.

Caulfield says parents should strongly consider donating to the public bank if they have the option.

For the Ford family, in Guelph, Tristan's successful cord blood transplant was a full circle moment. His older sister had donated her umbilical cord blood to the public bank when she was born, but she wasn't a match. It was a stranger who saved Tristan's life.

"I believe if you put good out in the world you get it back and our story is a perfect example of getting things back."