doi:10.1038/nindia.2015.19 Published online 10 February 2015
Researchers have converted coral carbonates into hydroxyapatite, which aids the growth of bone cells when loaded with growth factor proteins1. This hydroxyapatite loaded with growth-factor protein can act as a bone-regenerating scaffold, which could potentially be implanted in patients to repair bone tissue that has been damaged as a result of injury or arthritic diseases.
Bone grafts using the patient’s own tissue and cadavers are widely used to treat bone defects, but such grafts can increase the risk of contracting diseases and trigger adverse immune responses.
To develop materials that can safely mimic the function and structure of natural bone tissue, the researchers synthesized hydroxyapatite by hydrothermally treating slices of a sea coral. They then loaded the hydroxyapatite with growth factor proteins that support bone and cartilage growth, such as bone morphogenetic protein-2 and insulin-like growth factor.
The researchers used the hydroxyapatite loaded with growth factors as scaffolds and probed how effectively they released the growth factors in artificial environments. They found that the scaffolds released about 77% of insulin-like growth factor and 98% of bone morphogenetic protein-2 over four weeks.
The researchers also investigated how effectively the scaffolds could repair bone defects in a rabbit’s tibia. They surgically creating a bone defect in a rabbit’s tibia and then implanted the scaffold in the defect. The scientists obtained X-ray images once a month for 3 months to assess the implant (scaffold) status, the implant–bone interface and new bone formation. After 90 days, the X-ray images showed that the implants loaded with growth factor proteins formed new bone tissue at the implant–bone interface and that this new tissue was almost as dense as natural bone.
The researchers say that this hydroxyapatite-based scaffold is promising for use in bone tissue engineering.
1. Nandi, S. K. et al. Converted marine coral hydroxyapatite implants with growth factors: in vivo bone regeneration. Mater. Sci. Eng. C 49, 816–823 (2015)