In order to use the multifunctional stem cells, the embryos have to be destroyed, an act some critics have likened to murder.
Geron is using discarded embryos from in-vitro fertilization procedures that were destined to be destroyed but that has not derailed some critics.
"The current lines of human embryonic stem cells are derived from living human embryos," David Prentice of the Family Research Council told "GMA."
"There is a concern that you're cannibalizing human lives for potential treatments."
Former President George W. Bush banned federally supported embryonic stem cell research during his administration.
Newly inaugurated President Obama has said he would relax such restrictions but the FDA's decision was not influenced by political timing, Okarma told the AP.
The slightly less controversial use of adult stem cells has been tested in humans but embryonic cells have better potential for more diverse treatments, Kiernan said.
"When you're dealing with a problem as vexing as spinal cord injury, you don't want to enter the arena with one hand tied behind your back," he said. "This liberates the scientists to go where science can take them. It takes the politics out of science and enables them to do their job."
For Kiernan, the FDA's approval marks a significant shift that's been years in the making.
"I think the parade has started and the FDA took its rightful place at the head of the parade," he said. "We've gone through eight years of fighting to get this kind of approval. That's why we're so elated to be on our way. That's the exciting part."