| Vasuclar disease, one of the most common diseases jeopardizing the health of the human being,is mainly treated by the vessel teansplantation technique. Therefore the source of vasuclar gratfs becomes the focus of the research.Currently there are three types of sources: autograft,allograft and artificial materials. Autogratfs have limited soueres. Allografts are easy to get immune rejection. Artificial materials are not appropriate for vascular gratfs of small caliber arteries. The development of tissue engineering provides a new approach for the source of vascular gratfs. Vascular tissue engineering is classified as a field that applies the nomral cells from the vascular wall and biologic degradable materials to produce, reconsturct and regenerate the vessel substitute, by which an ideal vascular graft is constructed in vitro that will not be obstructed for a long time without immunological reaction after implantation. Vascular tissue engineering makes it possible to reconsturct vascular model in vitro whose structure and function are the same as autogenous vessels, which may provide a promising therapy for vessels defects.Chitosan is a product which chitin is removed of the acetyl.It is a poly-catholyte polysaccharide which posses active Amido and Hydroxy, and can bind to the matter with polyanion.Because chitosan is nonpoisonous to human body and has satisfactory histocompatibility,it also can be degradated into the normal component of body, stanch, anti-infect,improving the body immunity,promoting the wound healing. It wound be used widely in many field and is very valuable in burn.Chitosan origins widely.Chitin,its prosoma,is about 100 hundred million ton in the world.Chitin is the second large organism resource in the world only less than cellulose.Chitin exists in the shell of shrimp,crab and so on,so its resource is abundant and it is cheap and valuable. However, in some fields ( especially in medicine and food industry) the application of this polysaccharide is limited by its high molecular weight resulting in its low solubility in aqueousmedia . Low molecular weight chitosan (LMWC) is a degradation product of chitosan. Some researches showed that LMWC seemed to have enhanced functional-biochemical significance compared to chitosans of higher molecular weights. Because of these properties, LMWC has been applied in the pharmaceutical field and biological materials fileds. Carboxymethyl chitosan is one of the most important derivatives of chitosan. It has many properties, such as improving density,good decentralization and emulsification, excellent retention-moisture,easily-formed film and hydrogel and so on . The advantage of carboxymethyl chitosan compared to chitosan is carboxymethyl chitosan can be dissolved in neutral aqueous solution while chitosan can only be dissolved in acidic aqueous solution and therefore it also has been used in many different fields.By solubility test, determination of pH valuewe, moisture determination, determination of sugar content, measurement of molecular weight and determination of deacetylating degree, we have studied the relevant physical and chemical properties of CMC and LMWC, which Provided a premise for application of chitosan and its derivatives.In our experiment , vascular smooth muscle cells(VSMC) and fibroblast(FB) of rat aorta were performed successfully by using collagenaseⅡdispersion method and were cultured for the research of vascuilar tissue engineering. Then we used cell culture and count method to study the efects of carboxymethyl chitosan (10,50,100,500,1000μg/mL) and low molecular weight chitosan(10,50,100,500,1000μg/mL) on cell number stimulated by new born bull serum incultured rat VSMC and FB at 24 h, 48 h and 72 h after cultured. Results reveal compared with control group, CMC promoted VSMC proliferation in a dose and time-dependent manner. LMWC also promoted VSMC proliferation, but with increase of action time, the proliferation rate reduced. Both CMC and LMWC promoted the growth of FB and the promoting effect was most significantly when the concentration of chitosan was 500μg/mL(P<0.01). At 48h after cultured, CMC can keep FB to proliferate most rapidly, and at 24h after cultured, LMWC kept FB to proliferate most rapidly.Our results showed that CMC and LMWC also promoted VSMC proliferation and FB proliferation significantly. The best concentration in which CMC kept VSMC and FB to proliferate most rapidly was 1000μg/mL and 500μg/mL respectively.So did LMWC. The results provided theoretical and experimental foundation for multiplication of the seeding cells in vitro.At the same time, this study provided new clues to the development of CMC and LMWC.
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