Rapid Prototyping Technology To Construct Tissue Engineering Bone Scaffold And The In Vitro Experiment

Background:Every year, many patients have to withstand pain of bone defect whichcaused by many factors such as trauma, infection and tumor. Those patientsrequire bone grafts. The current clinical routine treatment methods are subjectedto a number of limitations. The emergence of tissue engineering technology willbring new developing direction for the treatment of bone defect.Bone tissue engineering scaffolds have four key factors which are seed cells, bone scaffold, growth factors and environment. Bone scaffold is the core element of these four key factors. Bone scaffold has two key elements:1, bone tissue engineering scaffold materials;2, preparation of bone tissue engineering scaffold. There are many kinds of bone tissue engineering scaffold material nowadays. They are polymers (such as polycaprolactone, polylactic acid, polyurethane, PLA etc.), natural polymer (such as hydroxyapatite, tricalcium phosphate, etc.), natural polymer (such as chitosan, alginate, collagen, etc.), composite materials. Compared to other materials, polycaprolactone has many advantages, such as good biocompatibility,perfect compliance, good plasticity, the degradation rate and the mechanical strength of the material can be adjusted to matching the rate of new bone generation and the mechanical property of natural bone respectively according to the molecular weight, so it is widely used in soft tissue suture, bone tissue engineering scaffolds preparation, bone defect repair, drug delivery system and other fields.Traditional preparation methods of scaffolds have thermal induced phase separation, particle leaching method, dissolve salt method, etc. Due to the complexity of its production processing, people are unable to make individualized scaffolds and control porosity, pore diameter and connectivity rate among pores, so ideal bone tissue engineering scaffolds could not beprepared. With the development of industrial manufacturing technology, first three dimensional printer was made out in1986. Since then, rapid prototyping technology has developed rapidly. Nowadays, a lot of scholars devote to combing the rapid prototyping technology with tissue engineeringtechnology to create ideal scaffolds. Now the common methods of rapid prototyping technologies have selective laser sintering, stereo lithography technology, three dimensional printing technology, etc. Compared to other rapid prototyping technology, fused deposition molding technology has manyadvantages, such as the low cost of scaffold production and machine maintenance, etc. It is expected to become the ideal method to make bone tissue engineering scaffolds. This study use polycaprolactone as raw material, and take advantage of fused deposition molding to prepare bone scaffold, and study the biocompatibility and the physicochemical properties of the polycaprolactone scaffolds. Research purposes:Using rapid prototyping technology (RP) to build poly caprolacton (PCLS) support, testing its biocompatibility, and exploring the potential as bone tissue engineering scaffolds.Method:At first, we use CAD software to establish models which groups areno pore,300μm pores and500μm pores. The three kinds of models areall1mm high,10mm diameter round bracket. After hierarchical processingthe data, we use polycaprolactone as raw materials; take advantage of fused deposition technology to produce no pore,300μm diameter,500μmdiameter three kinds of polycaprolactone scaffolds. Then, we use field emission electron microscopy to scan scaffolds characterization, pycnometer method is used to test300μm diameter and500μm diameter of polycaprolactone scaffolds porosity. Second, MTT method is used to inspect scaffold material for cell proliferation, cell adhesionis observed under inverted microscope, adhesion on the stent is observed by scanning electron microscopecell morphology.Results:300μm and500μm diameter stents materials which is observed by naked eyes both have uniform pore size, neat distinct, both tent has good pore connectivity rate. MTT test result shows that all have no obvious cytotoxicity at1d,2d,3d, cytotoxicity for level1.Under inverted microscopewe found that the number of the cell adhesion without pore group and 500μm diameter group,300μm diameter group increases in turn. Under scanning electron microscope we found that the cells adhere tightly on stentsAccording to the above results, using rapid prototyping technology toprepare poly caprolactone scaffolds has high porosity, good connectivity rate between pores, well biocompatibility and perfect cell adhesion, whichis expected to become the bone tissue engineering scaffolds.The innovation of the experiment lies in using fused deposition molding which is one of the rapid prototyping technologies to prepare poly caprolactone stents, and testing its physical and chemical properties by MTTmethods, scanning electron microscope and inverted fluorescence microscope, porosity determination.biological compatibility, which provides theorysupport for the later bone defect animal experiments.