Nanofibrous scaffolds for bone and cartilage regeneration

Bone, cartilage, and their composites in various joints are the most important components that form the skeletal structure and enable motion and movements of the body. Their disease and/or loss are most debilitating and afflict millions of Americans, reducing productivity and deteriorating quality of life. Due to limited treatments, scientists, engineers, and clinical doctors are investigating new tissue engineering solutions. In tissue engineering approaches, scaffolds are artificially designed temporary matrices that accommodate stem/progenitor cells and provide both physical and biological signals to guide cell differentiation and 3D tissue regeneration but eventually degrade and leave behind regenerated functional tissues or organs. Therefore, scaffolds often substantially benefit from mimicking certain features of the natural extracellular matrix (ECM) and designing certain engineered features to facilitate cell repopulation, mass transportation, and mechanical and biological cues for cells to regenerate tissue. This review article focuses on the design, synthesis, fabrication, and functionalization of nanofibrous materials to mimic the ECM, deliver biological signals, and integrate various engineering design features such as pore shape, size, connectivity, tissue architectures, and anatomic tissue/organ shapes to guide 3D tissue regeneration. In addition to biological and physical principles of scaffold design and fabrication, we also provide several examples of specific applications of these advanced nanofibrous scaffolds for bone, cartilage, and their associated composite tissue regeneration in osteochondral defects. We also discuss the interdisciplinary and multidisciplinary nature of these research directions, the importance of collaborations across disciplines, and the perspectives of future developments in the field.