On a brilliant day in April, tens of thousands of baseball fans stream past Jonathan Thomas's office towards AT&T Park for the first home game of the San Francisco Giants 2014 season. Thomas's standing desk faces away from the window, but the cheering throngs are never far from his mind.

Thomas chairs the board of the California Institute for Regenerative Medicine (CIRM), the US$3-billion agency hailed by scientists around the world for setting a benchmark for stem-cell research funding. But scientists will not be the ones who decide what becomes of CIRM when the cash runs out in 2017. Instead, it will be the orange-and-black-clad masses walking past Thomas's window. And to win their support, Thomas knows that the agency needs to prove that their collective investment has been worthwhile. We need to drive as many projects to the patient as soon as possible, he says.

Californians voted CIRM into existence in 2004, making it the largest funder of stem-cell work in the world. The money the proceeds of bond sales that must be repaid with $3 billion in interest by taxpayers helped to bring 130 scientists to the state, and created several thousand jobs there. It has funded research that led to the publication of more than 1,700 papers, and it has contributed to five early clinical trials.

The institute has navigated a difficult path, however. CIRM had to revamp its structure and practices in response to complaints about inefficiency and potential conflicts of interest. It has also had to adapt its mission to seismic shifts in stem-cell science.

Now, ten years after taking off, the agency is fighting for its future. It has a new president, businessman Randal Mills, who replaces biologist Alan Trounson. Its backers have begun to chart a course for once again reaching out to voters, this time for $5 billion (with another $5 billion in interest) in 2016. And it is under intense pressure to produce results that truly matter to the public.

Whether or not CIRM succeeds, it will serve as a test bed for innovative approaches to funding. It could be a model for moving technologies to patients when conventional funding sources are not interested.

Much of what is celebrated and lamented about CIRM can be traced back to the Palo Alto real-estate developer who conceived of it: Robert Klein. Although officially retired from CIRM he chaired the board from 2004 to 2011 (see 'State of funding') Klein's office is adorned with mementos of the agency: a commemorative shovel from the groundbreaking of a CIRM-funded stem-cell research centre, and a photo of him with former governor Arnold Schwarzenegger at the ribbon-cutting ceremony.

Liz Hafalia/San Francisco Chronicle/Polaris/eyevine

Patient advocates and parents at a 2012 meeting in which US$100 million in CIRM grants were approved.

It was Klein's idea to ask voters to support stem-cell research in 2004, through a ballot measure called Proposition 71. When he succeeded, CIRM instilled a kind of euphoria in stem-cell scientists, who were at the time still reeling from a 2001 decree by then-President George W. Bush that severely limited federal funding for embryonic-stem-cell research. California's commitment removed this roadblock and revealed that many in the state and the country supported the research.

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