Peyton Manning underwent a stem-cell procedure in Europe before having neck surgery recently, Fox’s Jay Glazer reported today.

The treatment is not used in the United States and Manning sought a number of consultations and therapies before undergoing anterior fusion surgery Sept. 8. Manning, 35, has had three procedures on his neck in 19 months, but the Colts continue to hope he’ll be available this season. He remains on the active list and reportedly made his first appearance at the Colts’ facility Friday and Saturday.

According to ESPN, Manning received therapy and watched part of practice Friday.