The Aqueous Extract Of Angelica Sinensis Inhibits Wear Debris-Induced Inflammatory Osteolysis

Joint replacement surgery is the best way to solute end-stage joint disorderwhich always accompany with pain, deformity, lack of range of motion andother dysfunctions. With developing of prosthesis design, emerging of newmaterials, improving of manufacturing technology and method of fixation, thesurvival rate of implants are improving and complications are decreased. But insome patients who once had a good fixiation of prosthesis, aseptic loosening isstill found with normal daily activities within a decade. This directly affected theoutcome of the operation and the patient’s life quality. Previously, asepticloosening was considered to be induced by a series of biomechanics factors,such as, fixiation location, micromotion, stress shielding, etc.. But now,researchers have focused on a new aspect which is wear debris particulatesinduced osteolysis. In this process, through several steps, such as, wear debrisparticulates generation, macrophage recuriment, phagocytosis, proinflammatorycytokines release, osteoclastogenesis, bone resorption, osteoclast was activatedand bone resorption was generated around the prosthesis. The chronicinflammation induced by wear debris particulates played a key role in all process. After particles phagocytosed by macrophages, a wide spectrum ofcytokines was released. TNF-α and IL-1β were most important among all thesecytokines. They modulated generation, differentiation and activation ofosteoclast through several signal pathways, and induced bone resorption withRANKL synergistically. Revision surgery is still the major way to treat patientswho suffered from osteolysis after joint replacement. However, revisionoperations not only let the patient suffer the pain physically, but also waste ahuge amount of medical resources of the society. Nowadays, more and moreresearchers and physicians are keen on pharmacotherapy of this disease. Thepurpose of this study is to investigate effects of the aqueous extract of AngelicaSinensis on inflammatory cytokines release, and wear debris particles inducedosteolysis.Ultra high molecular weight polyethylene(UHMWPE) particles were usedto induce inflammation in RAW264.7cell and C57BL/6J mice. AngelicaSinensis extract was obtained through a series of purification steps, and dividedinto high dose group and low dose group during the research of cell culture,tissue culture and animal treatment. After72hours culture with optimal particles,supernatants were collected for cytokine analysis. Calvaria were harvested fromthe mice model after10days treatment with the AS extract. Six calvaria of eachgroup were cultured into medium for72hours for analyzing cytokine generatedin vivo. Histologic analyses and micro computed tomography(micro-CT) scanwere used to determine osteoclastogenesis and inflammatory bone resorptionbetween different dose groups.The in vitro cell culture results showed no toxic side effects whenco-culture murine macrophage RAW264.7cells with Angelica Sinensiswater-soluble extract, and the extract could inhibit UHMWPE wear particlesinduced proinflammatory cytokines production. Using AS extract treated UHMWPE wear particles induced mouse calvarial osteolysis model showed thatthe drug in a low dose could reduce proinflammatory cytokines production,osteoclasts formation and the area of osteolysis, but no statistical significantdifference was found between this group and positive control group. However,when using high dose drug therapy, the concentration of proinflammatorycytokines, the number of osteoclasts and the area of osteolysis were significantlyreduced compared to positive control group. And this effect showed a dosedependent manner. Furthermore, the three dimensional reconstruction data of thecalavaria, such as, BMC, BMD, BV/TV, CMT also showed a same trend whencomparing with the data from two dimensional slices.Joint replacement is the best way to solve end-stage joint disorders. Asepticloosening of the implants is the major complication impacting the outcome ofthis kind of operation. A lot of medications have been tested to inhibit thiscomplication, such as, TNF-α inhibitors, bisphosphonates drugs, osteoprotegerin(OPG), RANKL-RANK signaling pathway inhibitors, non-steroidalanti-inflammatory drugs, tetracyclines, injected cytokines, etc.. However, it ishard to find a medicine which is specific for the treatment of prostheticosteolysis induced by wear particles. This study demonstrated that the aqueousextract of Angelica Sinensis could inhibit UHMWPE inducedosteoclastogenensis and related bone resorption in vitro and in vivo throughtinhibiting the release of proinflammatory cytokines by macrophages. Thisstudy suggests a potential resolution of inhibiting wear debris particles inducedinflammatory bone resorption, as well as a possible way of inhibiting asepticloosening after joint replacement surgery.