Both Brantly and Writebol remain in "stable, but grave condition" according to the statement.
"However, Dr. Brantly received a unit of blood from a 14-year-old boy who had survived Ebola because of Dr. Brantly’s care," Franklin Graham, president of Samaritan’s Purse, said in a statement. "The young boy and his family wanted to be able to help the doctor that saved his life."
Samaritan’s Purse is currently evacuating all but the most essential members of its organization from the region because of the outbreak.
The two American patients stricken with Ebola were to be flown from Africa to the U.S., ABC News later learned.
The patients will be transported one by one, sources said.
Meanwhile, there are plans to transfer a patient with Ebola virus infection to Emory University Hospital's special facility containment unit within the next several days, hospital officials said Thursday in a statement. Officials added that it's unclear when the patient will arrive in Atlanta.