Zebrafish Head (IMAGE) University of Southern California Caption Muscle and Medicine reported that hundreds of NFL players have invested in using stem cells to treat injuries. The publication revealed one NFL linebacker 'paid $6,000 a pop for a 1-milliliter vial of donated placenta tissue containing stem cells to be injected into each of his beat-up knees.' Now USC research shows that stem cells could one day be stimulated to make a special type of cartilage to help repair large, hard-to-heal bone fractures. Credit Sandeep Paul and Seth Ruffins Usage Restrictions Please use caption and credit information. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.