Progress in Tissue Engineered Bone, Matching Natural Bone Structure
Researchers have announced progress in the production of larger sections of bone for transplantation. Once transplanted, the new bone serves as a template to provoke further regeneration to match the structure of the natural bone that is replaced. Based on results from animal studies, this seems a promising approach:
A new technique repairs large bone defects in the head and face by using lab-grown living bone, tailored to the patient and the defect being treated. This is the first time researchers have grown living bone that precisely replicates the original anatomical structure, using autologous stem cells derived from a small sample of the recipient's fat. "We've been able to show, in a clinical-size porcine model of jaw repair, that this bone, grown in vitro and then implanted, can seamlessly regenerate a large defect while providing mechanical function. The need is huge, especially for congenital defects, trauma, and bone repair after cancer surgery. The quality of the regenerated tissue, including vascularization with blood perfusion, exceeds what has been achieved using other approaches. So this is a very exciting step forward in improving regenerative medicine options for patients with craniofacial defects, and we hope to start clinical trials within a few years."
Researchers fabricated a scaffold and bioreactor chamber based on images of the weight-bearing jaw defect, to provide a perfect anatomical fit. The scaffold they built enabled bone formation without the use of growth factors, and also provided mechanical function, both of which are unique advantages for clinical application. They then isolated the recipient's own stem cells from a fat sample and, in just three weeks, formed the bone within a scaffold made from bone matrix, in a custom-designed perfused bioreactor. An unexpected outcome was that the lab-grown bone, when implanted, was gradually replaced by new bone formed by the body, a result not seen with the implantation of a scaffold alone, without cells. "Our lab-grown living bone serves as an 'instructive' template for active bone remodeling rather than as a definitive implant. This feature is what makes our implant an integral part of the patient's own bone, allowing it to actively adapt to changes in the body throughout its life."
The team are now including a cartilage layer in the bioengineered living bone tissue to study bone regeneration in complex defects of the head and face. They are also advancing their technology through advanced preclinical trials, and in planning stages with the FDA for clinical trials, through the company epiBone.