Figure 14.

Poly(ethylene glycol)-4-maleimide (PEG-4MAL) “mechanical pillows” loaded with poly(lactic-co-glycolic acid) (PLGA)-dexamethasone (Dex) nanoparticles (NPs) in a load-induced model of osteoarthritis (OA). (A) Schematic showing the formation and delivery of PEG-4MAL hydrogels with NPs and their method of therapeutic retention while maintaining viscoelastic properties under daily mechanical loading. The drug is released under protease-rich conditions. (B) In OA-induced mice, these “mechanical pillows” attenuated in vivo osteophyte formation, as shown by the mean medial-lateral width of the osteophytes from three representative sections in the joint (posterior, middle, and anterior). n = 5 mice/group. φp < 0.05 for loading; and *p < 0.05 for hydrogel vs. no hydrogel nested by loading. (C) This, along with attenuation of cartilage damage, is shown by representative images of the joint with Safranin O and fast green-staining. Cartilage erosion is indicated with arrowheads and osteophyte formation with ellipses. Cartilage scale bars = 100 μm. Osteophyte scale bars = 200 μm. Reproduced under the Creative Commons CC BY License.^[197] Copyright 2019, D. T. Holyoak, T. A. Wheeler, M. C. H. van der Muelen, and A. Singh.