Board Certified M.D.s

Colorado Stem Cell Center proudly delivers regenerative health procedures with a focus on the best outcomes. We are one of the only clinics in the state to use Board Certified M.D.s.

Robert J. Bess, M.D., FACS, grew up in Denver, Colorado and enjoys family activities such as travel, golf, skiing and daily workouts. The active and athletic lifestyle Dr. Bess embraces helps him to understand the needs of patients who wish to feel their best and get back to work and pain-free living as quickly as possible. Coming from a large Denver family and having children of his own, makes Dr. Bess excellent with treating all ages from children to seniors. In fact, Dr. Bess was the Director for the Children’s Hospital fracture clinic for 8 years.

Dr. Bess attended Cherry Creek High School where he lettered in football and baseball. Dr. Bess remained involved in Creek athletics by being the football team doctor for 15 years. Dr. Bess played baseball for the University of Arizona and graduated from the University of Colorado. Dr. Bess completed his medical school, internship and residency at the University of Colorado, as well. Dr. Bess completed a Trauma fellowship where he studied in Switzerland and Germany and later a spine fellowship where he spent 6 months studying in Nottingham, England. These international relationships enhanced Dr. Bess’ knowledge with advancing technologies.

Dr. Bess has been a prominent Colorado surgeon for 38 years. His competence, confidence, and compassion inspire a deep comfort level with his patients. While practicing in Colorado, Dr. Bess held numerous positions of respect amongst his peers, including former clinical faculty at Denver Health and associate clinical professor of orthopaedics at University of Colorado. Dr. Bess is a former president of the Colorado chapter of the Western Orthopaedic Association and founder of the Orthopaedic Trauma Symposium.

Dr. Bess has lectured nationally and internationally and currently serves as Medical Director of the Bioscience division of Korean company, Aegis Spine (

Jack Rentz, MD, is passionate about helping his patients become pain free. Board-certified in anesthesia and pain medicine, Dr. Rentz came to Colorado to help patients get back to the fantastic Colorado lifestyle that drew him and his family from their southern roots to the Rocky Mountains.

After completing his undergraduate degree at the University of Georgia, he attended the Medical School of Georgia where he received his doctorate. Dr. Rentz then moved to New Orleans where he completed his residency in anesthesiology at Ochsner Hospital. There he was honored to serve as chief resident before receiving a fellowship at the prestigious Pain Medicine Center at Texas Tech University in Lubbock, TX. After visiting Colorado with his family, Dr. Rentz decided to move to the Metro Denver area to help patients get back to the things they love to do in this beautiful area.

Dr. Rentz is excited about serving his patients at his practice,Denver Diagnostic Pain, where his goal is to provide the highest level of care to those who entrust him with their health. Each patient that comes to his practice is on a journey to improve their quality of living and choosing to partner with Dr. Rentz along the way. This is a responsibility with which he is honored to be trusted.

When he’s not helping patients, Dr. Rentz can be found skiing,hiking, camping and loving the Colorado outdoors with his wife and two kids. He is a man of faith, which helps him as he treats his patients as well as navigates daily life.