469435 Magneto-Responsive Bionanocomposite Hydrogels As Injectable Scaffolds for Osteochondral Tissue Regeneration
Hydrogel scaffolds capable of delivering viable stem cell populations to the cartilage defect and responding to external stimuli, such as a magnetic field, could be used to influence stem cell behavior and guide the reconstruction of a heterogeneous tissue structure. In particular, polymer-based hydrogels made from thermogelling macromers, such as poly(N-isopropylacrylamide) (pNiPAAm), offer promise as in situ forming injectable scaffolds capable of delivering viable stem cell populations in vivo. Furthermore, recent studies have discovered that cytocompatible, hydrophilic polyamidoamine (PAMAM) crosslinkers can counteract pNiPAAm’s natural tendency to undergo syneresis post thermogelation,[3, 4] thus enabling these materials to completely fill irregularly-shaped tissue defects and promote integration with surrounding tissue.
The aim of this study was to investigate the efficacy of using a magneto-responsive injectable hydrogel to deliver viable stem cell populations and then stimulate osteochondral tissue regeneration through magnetically-actuated mechanical force. Functional paramagnetic iron (III) oxide Fe3O4 nanoparticles were incorporated into a dual-gelling pNiPAAm-based hydrogel with degradable PAMAM-based crosslinking macromers. The physical properties of the hydrogel were assessed by rheology and scanning electron microscopy (SEM), and magnetic properties of the hydrogel were determined by superconducting quantum interference device (SQUID) magnetometry and tangential force measurements. In situ delivery of viable cell populations in the bionanocomposite hydrogels was demonstrated by fluorescent microscopy and biochemical assays. Finally, the effects of magnetic stimulation on stem cell differentiation were investigated.
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