BMPs and PDGFs are examples of which exogenous factor influencing bone remodeling?

• A. Growth factors
• B. Collagens
• C. Surgery
• D. Gene therapy

Answer: (A)

Growth factors are signaling proteins that regulate how bone cells proliferate, differentiate, and produce matrix during remodeling. BMPs, part of the bone morphogenetic protein family, are strong osteoinductive signals that drive mesenchymal stem cells to become osteoblasts and form new bone. PDGFs, released by platelets and other cells, act as mitogens and chemotactic cues, recruiting progenitor cells to the remodeling site and supporting new blood vessel formation. Because these factors can be supplied from outside the body to enhance healing, they are considered exogenous. They are not structural components like collagens, nor a surgical procedure, nor a gene therapy approach; their key function here is to act as growth factors that modulate bone remodeling.