Image copyright SPL Image caption Embryonic stem cells

The world's first official trial using human embryonic stem cells in patients has been halted.

Geron, based in California, made the sudden announcement that it was halting further work in this field.

In a statement the company said in the "current environment of capital scarcity and uncertain economic conditions" it had decided to concentrate instead on developing cancer treatments.

Geron said it was seeking partners to enable further development of its stem cell programmes. The press statement implies the decision is purely a financial one - by stopping its stem cell programme it will cut its workforce by more than a third and save millions of dollars.

But the company has already invested tens of millions in the stem cell therapy over the past decade. Its submission to the US Food and Drug Administration to conduct the first trial in patients of human embryonic stem cells was the largest and most complex ever submitted.

Geron had injected stem cells into the spine of a small number of spinal patients to test safety. In its statement the company said the treatment had been "well tolerated with no serious adverse events".

The decision does seem to be extraordinary given the huge investment of time and resources. When I visited Geron nearly three years ago, the then chief executive Dr Tom Okarma claimed the technology had an incredible future (Green light for US stem cell work):

"What stem cells promise for a heart attack or spinal cord injury or diabetes is that you go to the hospital, you receive these cells and you go home with a repaired organ, that has been repaired by new heart cells or new new nerve cells or new islet cells that have been made from embryonic stem cells."

If that future exists, it won't be Geron that will now lead the way.

Ben Sykes, Executive Director of the UK National Stem Cell Network, said:

"Stem cell research continues to show great promise in helping many people currently suffering from incurable conditions and injuries. It is disappointing that Geron has taken the decision to stop its spinal cord injury trial but we hope that the company is able to find new partners who can take on the work and provide the necessary finance."

Joanna Knott, Co-Founder and Chair of SpinalCure Australia said: "This is incredibly sad and frustrating news for people with spinal injuries and their families. It is devastating for those people who will have a spinal injury and may as a result of this research been cured.

Daniel Heumann, who is on the board of the Christopher and Dana Reeve Foundation, was more forthright in The Washington Post online which reported him as saying: "I'm disgusted. It makes me sick. To get people's hopes up and then do this for financial reasons is despicable. They're treating us like lab rats."

John Martin, Professor of Cardiovascular Medicine at University College London said: "The Geron trial had no real chance of success because of the design and the disease targeted. It was an intrinsically flawed study. And for that reasons we should not be describing this as a set back.

"The first trials of stem cell that will give an answer are our own in the heart. The heart is an organ that can give quantitative data of quality."

Josephine Quintavalle from the group Comment on Reproductive Ethics said: "At long last after 10 years of unremitting hype, reality has caught up with embryonic stem cell claims. If Geron is abandoning this project it is because it is simply not working, despite the millions of dollars and hot air that has been invested in the promotion of this research."