Experimental Study On Reducing Tendon Adhesion Based On Photothermal Effect Of Polydopamine Nanoparticle

Research background and purpose:Adhesion formation after tendon injury is a fibrosis response between the injured tendon and surrounding tissues.Myofibroblasts with α-smooth muscle actin(α-SMA)play a crucial role in fibrosis.The conversion from fibroblasts to myofibroblasts is mediated by c-Jun N-terminal kinase(JNK)signaling pathway;selective inhibition of JNK signaling pathway can attenuate fibrosis.Heat shock protein(HSP)72 can prevent the activation of JNK.The purpose of this study was to investigate whether polydopamine nanoparticle-based photothermal effect would attenuate adhesion formation in a rat model of the Achilles tendon laceration repair.Methods:A total of 27 adult male Sprague-Dawley rats were randomly divided into 3 groups(9 rats in each group),including polydopamine nanoparticle solution photothermal therapy group,PBS group,polydopamine nanoparticle solution group.After the Achilles tendon injury model was established.A total of 50μl of 10mg/ml polydopamine nanoparticle solution was buried around the Achilles tendon in the polydopamine nanoparticle solution photothermal therapy group.A total of 50μl of PBS was buried around the Achilles tendon in the PBS group.A total of 50μl of 10mg/ml polydopamine nanoparticle solution was buried around the Achilles tendon in the polydopamine nanoparticle solution group.And the skin was closed.After feeding for two weeks,5 rats in each group were randomly selected for HE staining,immunohistochemical staining for HSP72 and α-SMA,and the remaining 4 rats were used for Western blot determination of the expression levels of HSP72,JNK,p-JNK.The polydopamine nanoparticle photothermal therapy group irradiated the operation area on the 3rd,6th,9th,and 12th day after the operation,and the 808nm near-infrared(NIR)laser power intensity was 0.48 W/cm2.Results:(1)HE staining showed that tendon adhesion scores were significantly lower in the photothermal therapy group than in the PBS group and in the polydopamine nanoparticle solution group.(2)Western blot results showed that compared with the PBS group and the polydopamine nanoparticle solution group,the expression of HSP72 in the photothermal therapy group was significantly increased.Western blot results showed that compare with the PBS group and the polydopamine nanoparticle solution group,the expression of p-JNK in the photothermal therapy group was significantly decreased.(3)Immunohistochemical results showed that compared with the PBS group and the polydopamine nanoparticle solution group,the number of HSP72 positive cells was significantly increased in the photothermal therapy group.Immunohistochemical results showed that compared with the PBS group and the polydopamine nanoparticle solution group,the number of α-SMA positive cells was significantly decreased in the photothermal therapy group.Conclusion:(1)Polydopamine nanoparticle-based photothermal effect can reduce adhesion formation after Achilles tendon injury.(2)The possible mechanism of photothermal effect to reduce tendon adhesion is that HSP72 inhibits the conversion from fibroblasts to myofibroblasts by inhibiting the phosphorylation of JNK,so as to reduce adhesion formation after Achilles tendon injury.