The impotence the men in the study were experiencing was so bad that none of them were able to achieve an erection, even with the help of Viagra.
But after the conclusion of the study that lasted for three months, eight out of the 21 guys were once again able to have sex. A year on, and the affects are still apparent.
This promising new treatment brings hope to guys all around the world, with around half of all men over 40 experiencing some sort of erectile dysfunction. It's also a more beneficial, long-term option than Viagra which needs to be taken each time you have sex.
Scientists are planning a large trial later this year, and if all goes well a widely available treatment could be given to the public within three years.
Lead researcher Dr Martha Haahr said the therapy works by rejuvenating damaged nerves and blood vessels in the penis, and it's potentially much better than Viagra.
"It's very promising. This therapy is regenerating actual functino of the penis rather than just treating symptoms.
"So we could offer just one procedure. It would be attractive for many men, rather than constantly having to take pills and be reminded of their impotence.
"If it works in larger trials we will have a safe new treatment that is more effective than Viagra," said Haahr.