The UK Stem Cell Bank could be stocked by samples from only 150 random human embryos, making it more practical than was previously thought, scientists say.
Stem cells hold great promise for new therapies
Stem cells from these embryos would be enough to provide a good tissue match with two-thirds of the population, a University of Cambridge team reports.
Embryonic stem cells, which can become many kinds of mature tissue, have the potential to treat many diseases.
Opponents say "false hope" is being raised among "desperate patients".
The University of Cambridge team say in theory just 10 embryos would be enough for a viable bank in the UK - if they had exactly the right genetic make-up.
Potentially embryonic stem cells can be used to replace diseased or damaged tissue in conditions such as diabetes and neurodegenerative disorders.
Scientists believe that generating clinically viable stem cell types from spare IVF embryos could be much more practical and cost effective than the more controversial solution of therapeutic cloning.
No tissue match using donated stem cells could be perfect, but there are degrees of matching, all of which reduce the need to use powerful immunosuppressant drugs to prevent tissue rejection, and increase the longevity of the graft.
The Cambridge team analysed the cell surface type of 10,000 people taken from the organ donor register.
Each was assessed for the potential compatibility of their stem cells to 6,577 patients waiting for a kidney transplant.
The scientists calculated that cells from 150 random embryos would, on average, be enough to provide the best possible match for 13% of recipients, a favourable level of match for 65%, and some use for as many as 85%.
Adding more stem cell types to the potential donor pool seemed to have little effect.
When the donor pool was narrowed down to those with the best possible set of genetics, the researchers found that just 10 stem cell types would be enough to provide a favourable level of match for 78% of recipients.
'Obscured by hype'
However, the researchers also found that tissue matching was much less likely for recipients from ethnic minorities.
To address this, either more stem cell types would need to be generated from these groups, or the UK Stem Cell Bank - one of the first in the world - would need to collaborate with other stem cell banks around the world.
At present the UK bank contains stem cells suitable only for research, not medical treatment.
Researcher Professor Roger Pedersen told the BBC News website: "What this research tells us is that the number of lines needed to achieve a significant clinical value is in the practical realm."
Professor Pedersen said researchers were already generating stem cell lines from embryos discarded from IVF treatment.
However, he said that focusing on generating just the most useful stem cell types would require additional regulatory review.
Dr Glyn Stacey, director of the UK Stem Cell Bank, said it was important that scientists were attempting to pin down how many stem cell lines were needed.
However, he said: "We are still a long way away in terms of establishing the basic cell culture methods.
"We also do not know whether all stem cell lines will give the full range of tissues."
The charity Life said research had shown that adult stem cells had more immediate potential to treat disease than those taken from embryos.
Spokesman Matthew O'Gorman said: "The UK stem cell debate is obscured by hype which only serves to raise false hope among desperate patients.
"Embryonic stem cell research involves destructive experiments on tiny human beings, that is why it has been outlawed in the majority of countries worldwide."