Drug Delivery Systems for Bone

Repair and regeneration of large or compromised bone defects is a significant clinical challenge. Autologous bone-grafting procedures offer a partial solution to functional repair of missing tissue, but face complications with a heavily limited supply and donor site morbidity concerns. Bone tissue engineering approaches seek to marry a combination of biomaterial scaffolds, stem cells, and appropriate drug or growth factor delivery to promote endogenous new bone formation. Central to this is the engineering approach’s interaction with the reparative signals and cells, as bone regeneration is characterized by numerous spatiotemporal signaling cascades that mediate the proliferation, migration, and differentiation of many different bone healing-related cell types. Many drugs in clinical use currently show marked improvements in bone healing, yet many of these are marred by high cost and/or low release efficiency, long-term safety concerns, or are unable to sufficiently promote new bone formation alone. In this chapter, alternative strategies to the current drug delivery techniques and how they address the challenges facing drug delivery for bone healing and regeneration, as well as some future perspectives in the evolution of drug delivery techniques, will be discussed.