The 49-year-old Walter Bast also regained the use of his right arm after the revolutionary treatment, which prevents brain cells from dying, reports the Telegraph.
If the treatment's further trials prove successful, the method, called CellBeads, could be available in the market in as little as five years, providing fresh hope for people who suffer a hemorrhagic stroke, where a blood vessel in the brain bursts.
The treatment involves cutting away part of the skull to tie off leaking blood vessels and remove blood from the brain. Then, surgeons insert the 2cm by 2cm 'teabag' filled with capsules stuffed with around a million stem cells.
The stem cells, taken from bone marrow, have been genetically engineered to make a drug known as CM1 that protects brain cells from dying. This lets the cells rejuvenate and repair the damage done by the stroke.
After around two weeks, doctors at the International Neuroscience-Institute in Hanover, Germany, removed the 'teabag', resulting in Bast regaining his speech and the use of his right arm.
The treatment is the brainchild of scientists at the British medical technology firm Biocompatibles International, based in Farnham, Surrey.