| Tissue engineering aims to restore tissue structure and recover function through replacing damaged tissues and stimulating regeneration with porous scaffolds,which serve as carriers for various drugs,bioactive factors and cells.It is common to prepare scaffolds with highly similar structure and composition according to the principle of biomimetic.In this thesis,tissue engineering porous composite scaffolds have been developed based on the principle of biomimetic and characteristics of skin and bone,and their relevant characterization and evaluation of the ability to induce tissue regeneration have been carried out.Acellular dermal matrix(ADM)is a natural material highly similar to skin derived from skin dermis tissues,which contains many bioactive ingredients.Therefore,it is a good candidate for preparing scaffolds for wound healing.According to the clinical requirement of wound healing,ADM derived from swine skin tissues was made into a composite scaffold with biomimetic porous double-layered structure.The main ingredient of ADM is type?collagen,and its distribution is not concentrated.The internal pore diameter of the scaffold is about 100?200?m.The water absorption rate is 27.4±0.5%.The porosity is 96.1±2.0%,while the water vapor transmission rate is 952.6±55.5(g/m~2/day).It can maintain its own water for 3 hours under specific condition.These properties showed that the ADM scaffold could meet the basic requirements of moist wound healing.In vitro cytotoxicity experiments suggested no obvious cytotoxicity.Furthermore,the scaffolds demonstrated good performance in a rabbit burn model.The wound could be re-epithelialized in 21 days,and no scabs appeared during the repair process.The apatite composite nanomaterials were synthesized through the biomimetic template-controlled mineralization process,which simulated biomineralization in biological systems.The reaction system is scaled up to 30L,using collagen and citric acid as bi-templates,biomimetic apatite nanocomposite(s BHA)was successfully synthesized for a100g scale batch.Methacrylic anhydride modified gelatin(Gel-MA)and s BHA were mixed together to make a bio-ink with an inorganic content of up to 68%.A 55-layer porous composite scaffold(G-s BHA)for bone repair was printed without interruption with an accuracy of 200?m.Results of cyclic mineralization showed that a loose mineralized layer was formed on the surface of the G-s BHA scaffold.MC3T3-E1 cell culture experiments showed that G-s BHA scaffold could increase the ALP activity of cells by about 77%.A bottle-cap-like model was designed to repair rabbit skull critical dimension defects(diameter10mm).After the post scaffold implantation,the bone volume fraction(BV/TV)of rabbit skull defects was much higher compared to the control,and new blood vessels were observed after 8 weeks.Loading autologous platelet-rich plasma(PRP)on the scaffold before implantation was carried out,which could reduce the inflammatory response and red blood cell aggregation.In addition,some G-s BHA scaffolds degraded unevenly in vivo and more evidences are expected in further experiments.In summary,tissue engineering porous scaffolds prepared by using animal-derived materials such as collagen and gelatin,which possess high similarity incomposition and structure compared to tissues,are promising candidates for skin wound and bone repair. |
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