Under the right conditions, healthy bone tissue has the ability to fully regenerate. However, complete healing is often hindered by various factors, including the size of the defect and patient-specific comorbidities. To address these challenges, bone grafts are frequently used to treat defects and significant bone loss.
Bone grafts are the second most common tissue transplant in the United States, with allografts often used to stimulate bone growth in various medical procedures. Despite this, the occurrence of non-union post-treatment is approximately 10%, which has led to a growing demand for enhanced osteoconductive and osteoinductive products for bone tissue regeneration.1
Growth factors and proteins are key players in the bone repair process, enhancing the osteoinductive potential of bone grafts by recruiting and differentiating mesenchymal stem cells (MSCs).1 In certain cases, adding growth factors and proteins to allografts can further support tissue healing and optimize outcomes.
How Do They Work?
Proteins are essential components of bone, comprising about half of its volume and one-third of its mass. When a bone is fractured, the body requires protein to generate new bone for repair.2 Proteins help form collagen, the matrix of bone, and also assist the body in absorbing calcium, another crucial nutrient for bone health. This protein matrix is continuously remodeled, requiring a steady supply of amino acids and minerals to support bone formation and maintenance throughout life.3
The Process
Inflammation Phase: After a fracture, an inflammatory response is triggered, which leads to the recruitment of immune cells and the release of cytokines and growth factors. These elements initiate the healing process by attracting mesenchymal stem cells to the injury site.
Repair Phase: Growth factors like Bone Morphogenetic Proteins (BMPs), Transforming Growth Factor-beta (TGF-β), and Platelet-Derived Growth Factors (PDGF) stimulate the differentiation of MSCs into chondrocytes (cartilage-forming cells) and osteoblasts (bone-forming cells). This results in the formation of a soft callus made of collagen and cartilage, which eventually mineralizes into a hard callus of new bone.
Remodeling Phase: Proteins like osteocalcin, osteonectin, and osteopontin are involved in remodeling the newly formed bone. Osteoclasts resorb the temporary bone, while osteoblasts create new, stronger bone tissue, restoring the bone to its original shape and strength.5
Successful bone regeneration requires the delivery of sufficient growth factors to the injury site at the right time, with adequate responding cells available. In cases of extreme defects or in patients with multiple risk factors where bone repair is impaired, clinical research indicates that supplementing a bone graft with additional proteins and growth factors can aid the healing process and promote new bone formation.6
Types of Bone Grafts That Include Proteins and Growth Factors
Bone grafts that incorporate proteins and growth factors are designed to enhance healing by stimulating cellular activity, often using components that promote bone growth and regeneration.