It's uncertain if the procedure will ultimately help either player, but NFL Network's Albert Breer reported Friday that there is hope.
Namely in the experience of former Denver Broncos defensive lineman Jarvis Green, who opted for stem-cell therapy in 2010 and saw discomfort from multiple knee surgeries disappear.
"The pain was gone," Green said. "It was a tremendous difference in the pain level, my range of motion. It was amazing. I rented a house in Denver with an elevator, just to get by, and said nothing to coaches, because I was worried about getting cut. Two weeks later, I'm swimming and biking in the mountains. ... I went to camp, didn't miss a day of practice, ran every day, beat everyone in sprints."
There's no guarantee that Manning or Owens will see the same results.
"It's experimental," renowned orthopedic surgeon Dr. Neal ElAttrache told Breer. "The effects and benefits of it are not known yet. We don't know whether it's a bunch of nonsense or if it's highly effective."