| Objective: Through using PLGA, HA and nano-silver as basic materials to create poprous artificial material to recover the defective of tracheal cartilage of experimental dogs, the experiment can evaluate the effectivity of trachea reconstruction material in treatment of tracheal defects.Methods:1. Use 256 layer CT sanner to scan the experimental dog, reconstruct the general form of dog’s tracheal cartilage and measure its diameter and depth. Use CAD software to design model, export the punch model as STL file. Apply RP technology to get the precise stent mold.Using HA, PLGA as material to repair the tracheal defects, and take freeze-drying method to build artificial material bracket. 2. Using freeze-drying method to make samples(0.4×0.4×0.3cm) for different groups(HA group,PLGA/HA group and PLGA/HA and nano-silver group). Choose part of tracheal cartilage, digestive treatment with collagenase II, cartilage cells were gained by serial subcultivation. Insert the third generation of chondrocyte into 96-well plates and take them out at the first day, the third day, the fifth day and the seventh day individually. Using the MTT method to test the proliferation of chondrocyte. 3. Chossing ten experimental dogs(mongrel dogs, weight 10kg-15kg) and divide them into three groups randomly(the last one as blank controller group for the pre-test). Remove 3 cartilage rings to create damage. Put artificial material to replace the removed tracheal tissue and suture on it. Implant HA bracket into Group A experimental’s defective area, insert PLGA/HA bracket into Group B’s and insert PLGA/HA and nano-silver brecket into Group C’s. Observe all experimentals generally after surgery, according to the experiment schedule execute them after the first week, the forth week and the eighth week respectively. Using electronic laryngoscope to examine the dogs before execute them.After execute the experimental dogs, take out the implants observe the condition of new cartilage formation by HE stain.Results:1.MTT method shows the speed of cartilage cell proliferation in PLGA/HA group and PLGA/HA and nano-silver group were obviously higher than HA group, P<0.05 for the difference was statistically siginifance. This shows that the complex combination material of PLGA/HA can be more beneficial for the formation of cartilage cells than HA material only.2.For blank control group, the incision heal poorly and swelling. 8 weeks after the operation, a big mount of fibrous tissue proliferation can be observed, and lost the form of cartilagines tracheales.For Group A, swelling and exudation can be observed.Granulation can be found and the defect slightly collapsed after 4 and 8 weeks by electronic laryngoscope. 8 weeks after the operation, small quantity of cartilage tissue could be found at the defect, inflammatory reaction observed, a big mount of fibrous tissue proliferation.For Group B, swelling and exudation can be observed.Granulation can be rarely found and there is no collapse after 1, 4 and 8 weeks by electronic laryngoscope. 8 weeks after the operation, a big mount of cartilage tissue and a lot of fibrillar tissue can be observed, inflammatory reaction is not obvious.For Group C, all incisions primarily healed.There is no inflammatory reaction or granulation on tracheal mucosa, the reconstructed tracheal lumens unobstructed. New cartilage tissue reformed after 8weeks, which was as the same as the normal tissue and had the same cover epithelium.Conclusion:1.Through the combination of CAD/CAM,RP technology and by using the freeze-drying method successfully prepared artificial scaffolds which can be designed with personalized bracket anatomical shape and have good tissue compatibility and stability.2.The porosity of the PLGA/HA and nano-silver brecket can benefit of chondrocyte formation.3.Nano-silver can resist bacterial effect which can efficiently reduce the inflammatory reaction.4.The success of this experiment provide an experimental basis for repair of the tracheal defect with the porous scaffold material, which can provide new technologies and methods for future clinical application. |
