An in Vivo Study of the Degradative Regularity about Three Porcine-derived Extracellular Matrix
|School||Second Military Medical University|
|Keywords||ECM Degradation Elastin GAGs Collagen|
Background:Repair of complex abdominal wall defects remains one of the most challengingprocedures facing reconstructive surgeons. Recognizing the challenges of each of thesecases and the unique problems facing the surgeon, the field of abdominal wallreconstruction was born. This new specialty has developed from the collaborative efforts ofgeneral surgeons, plastic surgeons, and trauma surgeons. Through these collaborativeefforts, defects that were once thought to be impossible to reconstruct can now be repaired,and patients who were left with a miserable quality of life are now offered hope. In order toovercome this problem, on the one hand, we focus on improving the skill of surgery, on theother hand, we are searching for the ideal material for repairing abdominal wall defect.We find that three-dimensional scaffolds play an important role in tissue engineering tocontrol cell functions and to promote the formation of new tissues and organs. Thescaffolds provide initial support to the seeded cells, localize the cells in the appropriatespaces, provide physical and biological cues for adhesion, migration, proliferation anddifferentiation. The scaffolds will be replaced by the cells’own matrices during theregeneration. Therefore, the scaffolds should be biocompatible, biodegradable and provideappropriate signals for the seeded cells to orchestrate the process. These specialrequirements drive the development of scaffolds and substrates that have the samefunctions as extracellular matrix (ECM)。The extracellular matrix (ECM) is by definition nature’s ideal biologic scaffoldmaterial. The ECM is custom designed and manufactured by the resident cells of eachtissue and organ and is in a state of dynamic equilibrium with its surroundingmicroenvironment. The structural and functional molecules of the ECM provide the meansby which adjacent cells communicate with each other and with the external environment.The ECM is obviously biocompatible since host cells produce their own matrix. The ECMalso provides a supportive medium or conduit for blood vessels, nerves and lymphatics andfor the diffusion of nutrients from the blood to the surrounding cells. In other words, theECM possesses all of the characteristics of the ideal tissue engineered scaffold orbiomaterial. ECM scaffolds consist of the structural and functional molecules secreted by theresident cells of each tissue and organ from which they are prepared. Therefore, thespecific composition and distribution of the ECM constituents will vary depending on thetissue source. The ECM scaffold derived from porcine small intestinal submucosa(SIS–ECM) is the biological scaffold material that has been most extensively characterized,and therefore will be used as a prototypical ECM scaffold. By dry weight, SIS–ECMscaffold is composed of greater than90%collagen. The large majority of the collagen istype I, with minor amounts of collagen types (Col) III, IV, V and VI also present. Urinarybladder matrix (UBM–ECM) also contains the same collagen types as SIS–ECM, withgreater amounts of Col III being present, as well as Col VII. Col VII is an importantcomponent of the epithelial basement membrane that distinguishes this particular ECMscaffold from most other ECM scaffold materials. SIS–ECM contains a variety ofglycosaminoglycans (GAGs), including heparin, heparin sulfate, chondroitin sulfate andhyaluronic acid. The amount of GAGs remaining in a tissue after decellularizationdepends greatly on the method of decellularization. For example, ionic detergents are oftenused in the decellularization process and such detergents can remove GAGs from the ECM.SIS–ECM has been shown to contain adhesion molecules such as fbronectin and laminin,and entactin. Various growth factors are also present in SIS–ECM, including transforminggrowth factor-B, and vascular endothelial growth factor(VEGF).Several of these growthfactors have been shown to retain their bioactivity even after terminal sterilization andlong-term storage. In summary,extracellular matrix have a complex composition with avariety of diverse molecules, The ability of an ECM harvested from one tissue to functionas a biological scaffold material for the same or different tissue may vary.The complex three-dimensional organization of the structural and functional moleculesof which the ECM is composed has not been fully characterized; therefore, synthesis ofthis biomaterial in the laboratory is not possible. Individual components of the ECM suchas collagen, laminin, fbronectin and hyaluronic acid can be isolated and used both in vitroand in vivo to facilitate cell growth and differentiation. Various forms of intact ECM havebeen used as biologic scaffolds to promote the constructive remodeling of tissues andorgans. These ECM scaffolds have been harvested from the small intestine, skin, liver,pancreas, and urinary bladder among other tissues. Many of these ECM materials havebeen commercialized for a variety of therapeutic applications. For example: Oasis（Healthpoint Company）、Restore(DePuy Company)、CuffPatch(Arthrotek Company)are made from porcine small intestinal submucosa. Axis dermi（sMentor Company）、AlloDerm（Lifecell Company）、Graft Jacket（Wright Medical Tech Company）are made from thehuman dermal. Pelvicol（Bard Company）、Permacol（Tissue Science LaboratoriesCompany）、Zimmer Collagen Patch（Tissue Science Laboratories Company）are madefrom the porcine dermal. Vascu-Guard（Synovis Surgical Company）、Peri-Guard（SynovisSurgical Company）、Dura-Guard（Synovis Surgical Company）are made of the bovinepericardial. These products have been approved by US Food and Drug Administration(FDA) to use for simple or complex surgical repair of abdominal wall defects.Objective:The purpose of this study is to research the degradative regularity about threeporcine-derived extracellular matrix (ECM): small intestine submucosa (P-SIS),pericardium (P-PC) and acellular dermal matrix (P-ADM), by quantitating the change ofelastin, glycosaminoglycans (GAGs), collagen I, collagen Ⅲ, and the collagen I:III ratio inmouse model.Methods:Part1: Preparing for ECMs and the histopathology examination after surgery in mouse.ECMs were prepared with traditional method.Animal experiments:60BALB/c mouse, weighting18~20g, Single cage to feed the animals,Abdominalwall defects(1.5cm×2cm)were created by surgery and were repaired with the same area ofP-SIS,P-ADM and P-PC, randomly divided into three groups (n=20), The animals weresacrificed at4and8weeks after surgery.3. Observation index:(1) general observation,(2) score of abdominal adhesions,(3)histopathology examination.Part2: An in vivo study of the degradative regularity about three porcine-derivedextracellular matrixAnimal experiments:60BALB/c mouse, weighting18~20g, Single cage to feed the animals,Abdominalwall defects(1.5cm×2cm)were created by surgery and were repaired with the same area of P-SIS,P-ADM and P-PC, randomly divided into three groups (n=20), The animals weresacrificed at4and8weeks after surgery.2.Observation index: quantitating the change of elastin, glycosaminoglycans (GAGs),collagen I, collagen Ⅲ, and the collagen I:III ratio.Results:1mouse was dead because of anesthetic accident, After8weeks, the abdominal walldefects of three groups could be repaired after surgery, and there was no obvious fistulaand infection case.The scores of abdominal adhesion about P-SIS group was lower than theother two groups. Compare with4weeks and8weeks after surgery, GAGs in P-ADMgroups were decreased(P<0.01); elastin(P<0.01）, GAGs(P<0.05) and collagen Ⅲ(P<0.05)in P-PC groups were increased; elastin(P<0.001）, GAGs (P<0.05), collagen I(P<0.01) andcollagen Ⅲ(P<0.05) in P-SIS groups were all increased; collagen I:III ratio in P-SISgroups was increased(P<0.01).Conclusion:the regeneration of elastin, GAGs and collagen in P-SIS groups was better than theother two groups, and P-SIS was good for anti-adhesion, relatively, P-SIS was an idealmaterial for tissue engineering application.