The Experimental Studies In Reparation Of The Segmental Bone Defects With Tissue Engineering Technology

The loss or failure of an organ or tissue is one of the most severe human health problems. It is also the main reason of human diseases and death. During the last two decades, because of the enormous develepment and intersection between cytobiology and biomaterial engineering science, tissue engineering has forged ahead rapidly as a novel frontier science. Its purpose is to research and invent the ideal tissue and orgen substitues based on principles and technique of those scientific disciplines. For this purpose, a complex should be preparaed by using a three-dimensional frame, a number of active seed cells expanded in vitro and some kinds of growth factors. The complex can provide an excellent environment of metabolism, proliferation and effective performing activity for seed cells and biological active growth factors. It is also the material base for forming the new tissues and organs which possess normal structure and function. Tissue engineering technology has been universally acknowledged as one of the most effective therapies for defective repairing and restructuring of some tissues and organs.The bone tissue reconstruction and reparation are one of the difficulties facing by orthopedist. Tissue engineering provides a new thought and way for solving these problems. Bone tissue engineering is a hot spot among the reseaches nowadays. Its main content includes three aspects of study, ①scaffolding materials which cells can be seeded on; ②seed cells characteristics; ③growth factors related with accelerating bone reconstruction. Of which, the first one is the core for the tissue engineering and the key if it can be for the clinical application. In this study, we took some long compact bones and spongy bones from rabbits to prepare the extracellular matrix material by applying NaOH cell-maceration methodfor the carrier of seed cells, autologous red marrow and osteoblast came from rabbit embryo's bone tissue and rhBMP2. We carried out a series of experimental studies to repair the segmental radius defects and allotopic osteoanagenesis in rabbits.Part One: Experimental Studies of Preparation of the Bone Tissue Engineering Frame Material by NaOH-Maceration Method and its BiocompatibilityObjective: To prepare a new natural bone tissue engineering carrier, observe its structure and research its biocompatibility and biodegradation in vivo.Methods:Radial diaphyses and iliac crests taken from the healthy rabbits were cross-linked with 2%glutaradehyde/4%paraformaldehyde mixed solution and immersed in 6%aqaeous solution of NaOH for 7days at room temperature, and then rinsed in distilled water for a couple of days, using ultrasonic wave (USW) cleaning to clear cellular pieces and removed reagent untill the distilled water was clear and pH＜7. Then putting it in the drying oven to make them dry. A series of examination about the materials were carried out including scanning electron microscope (SEM), biomechanics, experiment of biocompatibility and biodegradation in vivo and chemical composition analysis before and after implanted.Results:①SEM characteristic of the bone extracellular matrix material: Maceration of the bone tissues with a NaOH solution followed thorough washing by distilled water and USW effectively and sheerly removed the cellular elements. The main composition of extracellular matrix of compact bone, collagen fibrils and minerals, were preserved in the natural position and structure characteristic. The collagen fibrils arrangement formed networks and the minerals adhering to the surfaces of the collagen fibrils. The spongy bone treated by NaOH present with numerous orifices interlinked. Its surface looked rough and collagen fibrils' streaks could be seen on the surface. ②Results of the biomechanics: Theresults of resistant bending strength at three points and the resistant compressed strength of compact bone extracellular matrix frame(CBMF) were (0.0808±0.008)N, and(0.2453±0.078)N.The control group were(0.1035±0.017)N and(0.4675±0.07). The mechanical...