Biological Function And Biosafety Research Of The Absorbable Chitin Surgical Suture

Injury is inevitable in surgery and trauma. Clinically, suture is the most effectiveavenue among various methods for wound closure and healing during the last twodecades. With the development of the synthetic polymers, Polyglycolide (PGA) in the1970s, a new chapter has opened on absorbable sutures that got huge commercialsuccess. Nowadays, surgical suture has a huge market exceeding$1.3billion annually.Compared with traditional nonabsorbable suture materials, these absorbablepolymeric sutures have advantages on reproducible degradability in biologicalenvironment during the wound reconstruction progression, avoiding chronicundesirable tissue reactions. With the clinical needs of antimicrobial activity,biological safety and other physiological characteristics to surgical suture, absorbablechitin and chitosan (CS) nature sutures are of extensive attention. Chitin, a naturalalkaline polysaccharide, is one of the most promising biomaterials that can provideprotection from wound infection for its antimicrobial property. Moreover, thefiber-forming ability, biocompatibility, biodegradability and low immunogenicity ofchitin make it potential to be a promising biomaterial for absorbable suture. However,long degradation cycle and low mechanical strength limit the applications of chitinsutures.Acyl chitin (AC) is an acidylated chitin obtained using acetic anhydride mixedperchloric acid system. By wet spinning and weaving technique, AC is successfullydeveloped into a novel absorbable monocomponent multifilament surgical suture(USP2-0). The mechanical properties and biological safety were investigatedsystematically. Then, we performed the feasibility assessment of AC suture asabsorbable suture for wound healing on a linear incisional wound model, incomparison with Vicryl Plus suture (USP2-0), another commercially available multifilament suture. More over, the interaction of AC fibers with human keloidfibroblasts (HKFs) was also investigated. The main results are as follows:(1) Infrared spectrometry (FTIR) and X-ray diffraction (XRD) confirmed thechemical structures of the AC product. The CHN elemental analysis suggested thedegree of esterification was very close to2. The basic physical and chemicalproperties of the AC product met the quality standards of biomedical materials. TheMTT results revealed that AC membrane had no significant effects on L929cells. Onthe other hand, AC membrane was completely absorbed at about150d in vivo.(2) The basic physical and chemical properties of AC suture (USP2-0) met thequality standards of biomedical devices. Relevant mechanical parameters wereinvestigated and the results showed that the breaking strength and breaking elongationof AC suture were13.42±1.13N and16.77±2.67%respectively, meeting therequirement for conventional suturing of epithelial and connective tissue. More over,AC suture retained approximately63.0%of the original strength at14d in vivo.(3) The results showed that AC suture had no significant effects on L929cellsgrowth and the blood system, caused no obvious inflammatory reaction and had noobvious systemic toxicity. Additionally, AC suture (USP2-0) was completelyabsorbed at about42d in vivo and no obvious inflammatory reactions or other tissuereactions were observed.(4) It was demonstrated that AC suture significantly accelerated the woundhealing process on a linear full thickness wound model, with more collagen fibersrunning parallel to the epidermal layer, higher wound breaking strength, less woundhealing time and less scar. In addition, AC suture could enhance the expression oftransforming growth factor β1(TGF-β1) and secretion of Hydroxyproline (Hyp),leading to acceleration of the wound healing process.(5) AC fiber significantly inhibited the proliferation and adhesion of Humankeloid fibroblasts (HKFs), inhibited the expression of TGF-β1and reduced thesecretion of Hyp.In sum, this paper studied the basic physical, chemical and biological propertiesof a novel absorbable monocomponent multifilament AC surgical suture, and investigated its promotion of skin regeneration and inhibition of scars. All theseresults demonstrate the potential use of AC suture in short or middle term woundhealing, such as epithelial and connective tissue.