According to Official Guinness Records,
The earliest brain cell transplant was performed by a team of doctors from the University of Pittsburgh Medical Center, Pennsylvania, USA, on 23 June 1998. The aim of the operation was to reverse the damage which had been caused by a stroke to 62-year-old Alma Cerasini, who had suffered paralysis of her right arm and leg as well as the loss of most of her speech. The team has subsequently performed a further 11 operations of this type.
For a complete list of 1998 records, please visit 1998 Guinness Records in United States.