The Research On Controlled-released TGF-β3Tissue Engineering Synovial Sheath

BackgroundThe postoperative outcome of flexor tendon healing remains to be limited by flexortendon adhesion that reduces joint range of motion. Despite improvements in materials andsurgical technique, various pharmacological modalities and the evolution of rehabilitativetherapies, peritendinous adhesion formation continues to present a formidable challenge. Atpresent, the main measures of clinical prevention is to reduce the tendon and tendon sheathdamage, local inflammatory reaction and early postoperative exercise. But these measurescan not completely solve tendon adhesion, we need make further researches to find a bettertreatment.In recent years, the effort of transforming growth factor(TGF-β) on tendon healing hasbecome an important research area. TGF-β has been demonstrated to be a causal agent inadhesion formation in mesothelial tissues such as tendon, synovium and peritoneum.Inhibition of TGF-β by neutralizing antibodiesduring the early course of wound healing hasbeen shown to reduce markedly fibronectin production and adhesion formation.TGF-β, agrowth-factor family with numerous biologic activities related to wound healing,represents three mammalian isoforms, TGF-β1, TGF-β2, and TGF-β3. TGF-β1is known tobe involved in wound healing and scar formation, it has also been shown to play a role inboth tendon healing and adhesion formation. Meanwhile, in cutaneous wound healing,neutralization of TGF-β1and-β2or addition of TGF-β3reduces scar formation. Theresearch into mechanisms of skin scarring identifies TGF-β3as a potential antiscarringtherapy.TGF-β3is considered as the key factor to reducing adhesion formation in skin ortendon. So we think that treatments aimed at TGF-β3may reduce tendon adhesion.Tendon healing contains intrinsic and extrinsic processes that occur simultaneously.Intrinsic healing occurs within the tendon as a result of the activity of tenocytes and appropriate nutrition to them. Flexor tendons in the region of synovial sheaths are mainlynourished by synovial diffusion and the injured tendons can heal sufficiently through theintrinsic cellular activities without adhesion formation. Excision of the synovial sheathmost frequently results in adhesion. Restoration of synovial sheath integrity can preservenutrition of the tendons, provide them with smooth gliding surface for tendons, and candecrease peritendinous adhesions. One research about synovial sheath cell migratoryresponse to flexor tendon injury has been shown in a novel tendon healing modle. So wepropose to construct synovial sheath by tissue engineering technology and seed the synovialcells directly into the sheath, then cover damaged tendon to promote tendon surfacesynovial change. It may effectively reduce the formation of tendon adhesion.Chitosan,a nature polysaccharide,has emerged as a scaffold for tissue engineering.Because it has many advantages such as nontoxic, biocompatibility, biodegradability andlow immunogenicity. The three-dimensional chitosan scaffold, fabricated via freeze drying,can be used as in vitro seeding and growing of cells. Cells directly delivered into the porousscaffolds can maintain the phenotype and the ability of proliferation. For drug deliveryapplications, chitosan microspheres, fabricated by crosslinking-emulsion, have been usedfor the delivery of biologically active protein such as TGF–β1.Based on the above results, it is expected that if using chitosan as tissue engineeringscaffold and TGF-β3controlled-released microspheres system and then planting synovialcells to construct TGF-β3controlled-released tissue engineering synovial sheath, it mayeffectively reduce flexor tendon adhesionObjectiveTherefore, this study explored the possibility of in vivo reconstruction of tissueengineering sheath and focused synovial cells and TGF-β3as the main factors.Methods(1) To achieve a sustained release of TGF-β3,chitosan microspheres loaded withTGF-β3were prepared by emulsion-crosslinking method. The controlled release of TGF-3was monitored for7days. Three-dimensional chitosan scaffold was prepared bylyophilization. Then the TGF-β3loaded microspheres were introduced into the scaffold. All of them were observed by scanning electron microscope(SEM).(2)Synovial cells were cultured and identified by immunohistochemistry assessment.Then, synovial cells were collected to seed into the scaffold. MTT assay was used in cellproliferation and biocompatibility.Results1. The microspheres were spherical and the mean diameter of microspheres was28.5±4.3μm.2. The controlled release of TGF-β3from chitosan microspheres was monitored of7days, the accumulated release of TGF-β3reached46.2％±0.3%.3. The morphology of porous scaffold was uniform and the mean diameter ofinterconnected pores is180.4±35.3μm. The porosity was83.2％±0.6%.4. Most microspheres were seen to embed in the scaffold.5. By MTT assay, statistical analysis indicated that there was no significantdifference (p>0.05) in the cell viability among different groups.ConclusionThese results expanded the feasibility combinative strategies of controlled proteinrelease and tissue-engineered synovial sheath formation. Accordingly, this scaffold mightpossess a promising potential as a mean to preventing adhesion.