Syria played for the Cyclones as a true freshman during the 2014-15 season. He rushed for 47 yards on 20 carries and scored one touchdown.
He had battled both concussion and neck-related injuries over the past year, and had been shut down from playing this past spring.
Iowa State already lost running back DeVondrick Nealy when coach Paul Rhoads announced he was no longer part of the team.
Iowa State's leading rusher in 2014-15, Aaron Wimberly, graduated from the school in May.