(23h) Creating Biomaterial Gradients for Musculoskeletal Interfacial Tissue Engineering

Authors: 
Holloway, J. L., Arizona State University
Tindell, R., Arizona State University
Gualtieri, A., Arizona State University
Tissue engineering is an ever-growing field, which aims to advance current treatments for injuries and disease, through a combination of biomaterials, cells, and signaling molecules to restore tissue function. Of particular interest, musculoskeletal impediments are the second most frequent disability and affect over 1.7 billion people worldwide. Musculoskeletal tissues, such as bone, tendon, and cartilage tissue, are important for load bearing and everyday movement. Additionally, musculoskeletal tissues are heterogeneous, where these tissues connect and form chemical and physical gradients responsible for transferring load from one tissue type to another (i.e. tendon-bone interface). Electrospinning is a common technique for fabricating nanofibrous scaffolds that can mimic the structure of the native extracellular matrix (ECM). However, current electrospinning techniques do not easily allow for the replication of the chemical and physical gradients present in musculoskeletal interfacial tissues. In this work, magnetic electrospinning was utilized to produce a tunable fiber alignment gradient that mimics the physical gradient in the tendon-bone interface, where the tendon ECM is highly aligned and the bone ECM is not aligned. Magnetic electrospinning uses permanent magnets to create a magnetic field, where the electrospun fibers will align in the direction of the magnetic field and transition to unaligned fibers as the field weakens. As a proof of concept, electrospinning was performed using poly(caprolactone). Permanent magnet strips were selectively adhered onto a rotating collection mandrel to spatially control the size of the aligned fiber compartment of the scaffold. Fiber alignment percent was quantified using scanning electron microscopy and bright field images of the electrospun fibers as a function of scaffold length and with different magnet configurations. Results successfully show a high degree of fiber alignment on the surface and very close to the magnets with decreasing alignment at distances away from the magnet. Furthermore, by placing multiple magnets next to each other in “series” the length of the highly aligned compartment increases. Future research will combine this technique with offset electrospinning to independently control gradients in fiber alignment (via magnetic field) and chemistry (via degree of offset between electrospinning solutions) to better mimic the tendon-bone interfacial tissue.