(334f) Effects of Short-Term Magnetic Stimulation on MSCs Encapsulated in an Injectable, Magneto-Responsive Hydrogel

Osteoarthritis (OA) is a degenerative joint disease that occurs when articular cartilage begins to naturally degrade and causes severe disability in the lower extremities of the body. Every year, 3.1 million surgeries are done to treat the damage caused by OA^[1], and the cost of non-steroidal anti-inflammatory drugs (NSAIDs) exceeds $4 billion annually^[2]. The regeneration of damaged articular cartilage has been a main area of interest in the field of tissue engineering due to its inability to naturally regenerate. This lack of functional regeneration is primarily attributed to the innate avascular and heterogeneous tissue structure. Stimuli-responsive biomaterials, capable of responding to changes in the local environment, have emerged as promising scaffolds for applications in guiding the repair of a cartilage defect^[3]. In particular, hydrogels that are susceptible to variations in external magnetic fields could be used to spatiotemporally deliver the localized mechanical forces needed to promote and maintain growth of healthy cartilage^[4].

An injectable, magneto-responsive hydrogel was developed by chemically incorporating functional paramagnetic iron (III) oxide (Fe₃O₄) nanoparticles into a dual-gelling pNiPAAm-based hydrogel with degradable PAMAM-based crosslinking macromers. Rheological results showed that the nanoparticles played an active role as chemical crosslinkers[EA1] . Furthermore, the nanocomposite hydrogel’s physical and magnetic properties were determined utilizing differential scanning calorimetry, scanning electron microscopy (SEM), superconducting quantum interference device (SQUID) magnetometry, and tangential force measurements. Finally, the effects of short-term magnetic stimulation generated by an external magnetic field on encapsulated mesenchymal stem cells were evaluated through biochemical assays and gene expression. Together, these results demonstrated that this magneto-responsive hydrogel system holds promise as a non-invasive means to externally stimulate cell activity and promote regeneration in situ.

1. Arthritis Brochure. American Academy of Orthopaedic Surgeons. Available from: www.aaos.org.

2. Van Manen, M.D., J. Nace, and M.A. Mont, Management of primary knee osteoarthritis and indications for total knee arthroplasty for general practitioners. J Am Osteopath Assoc, 2012. 112(11): p. 709-15.

3. Li, Y., et al., Magnetic hydrogels and their potential biomedical applications. Advanced Functional Materials, 2013. 23(6): p. 660-672.

4. Pankhurst, Q.A., et al., Applications of magnetic nanoparticles in biomedicine. Journal of physics D: Applied physics, 2003. 36(13): p. R167.