Shear-responsive boundary-lubricated hydrogels attenuate osteoarthritis

Lipid-based boundary layers formed on liposome-containing hydrogels can facilitate lubrication.However,these boundary layers can be damaged by shear,resulting in decreased lubrication.Here,a shear-responsive boundary-lubricated drug-loaded hydrogel is created by incorporating celecoxib(CLX)-loaded liposomes within dynamic covalent bond-based hyaluronic acid(HA)hydrogels(CLX@Lipo@HA-gel).The dynamic cross-linked network enables the hydrogel to get restructured in response to shear,and the HA matrix allows the accumulation of internal liposome microreservoirs on the sliding surfaces,which results in the formation of boundary layers to provide stable lubrication.Moreover,hydration shells formed surrounding the hydrogel can retard the degradation process,thus helping in sustaining lubrication.Furthermore,in vitro and in vivo experiments found that CLX@Lipo@HA-gels can maintain anabolic-catabolic balance,alleviate cartilage wear,and attenuate osteoarthritis progression by delivering CLX and shear-responsive boundary lubrication.Overall,CLX@Lipo@HA-gels can serve as shear-responsive boundary lubricants and drug-delivery vehicles to alleviate friction-related diseases like osteoarthritis.

Exhausted local lactate accumulation via injectable nanozyme-functionalized hydrogel microsphere for inflammation relief and tissue regeneration

Local lactate accumulation greatly hinders tissue repair and regeneration under ischemic condition.Herein,an injectable microsphere(MS@MCL)for local lactate exhaustion was constructed by grafting manganese dioxide(MnO_(2))-lactate oxidase(LOX)composite nanozyme on microfluidic hyaluronic acid methacrylate(HAMA)microspheres via chemical bonds,achieving a long-term oxygen-promoted lactate exhaustion effect and a long half-life in vivo.The uniform and porous microspheres synthesized by microfluidic technology is beneficial to in situ injection therapy and improving encapsulation efficiency.Furthermore,chemical grafting into HAMA microspheres through amide reactions promoted local enzymatic concentration and activity enhancement.It was showed that the MS@MCL eliminated oxidative and inflammatory stress and promoted extracellular matrix metabolism and cell survival when co-cultured with nucleus pulposus cells(NPCs)in vitro.In the rat degenerative intervertebral disc model caused by lactate injection,MS@MCL showed a long-term therapeutic effect in reducing intervertebral height narrowing and preventing extracellular matrix(ECM)degradation as well as inflammatory damage in vivo.Altogether,this study confirms that this nanozyme-functionalized injectable MS@MCL effectively improves the regenerative and reparative effect in ischemic tissues by disposing of enriched lactate in local microenvironment.