Research Of Hydrogel And Cell Printing Technique For Skin Tissue Engineering

Essential elements of skin tissue engineering include seed cells,scaffold materials,and tissue construction.The basic principle of this technique is to establish a three-dimensional complex of cells and biomaterials to repair skin defects.3D bio-printing technology can accurately locate many types of matrix materials and cells,with pore structure control,wide size range and high production capacity.It has great potential in the construction of tissue engineering skin.In this paper,we carried out the experimental study of hydrogel scaffold preparation and skin cell printing using self-developed 3D bio-printing system.We analyzed the characteristics of hydraulic material and its extrusion process.The experimental results show that this system has good printing performance,and the constructed tissue scaffold can provide a suitable three-dimensional environment for the cells to grow.It includes:(1)Design and development of 3D bio-printing system for skin tissue engineering.We proposed a pneumatic printing scheme combined with the existing 3D bio-printing technology and the specific requirements of skin tissue engineering.This system can be divided into five parts:motion control system,feeding system,temperature control system,cross-linking system and environment control.It can be used with a variety of biological materials and cell printing research.(2)Analysis of extrusion process of hydrogel material.Based on the constitutive equation of power-law fluid,we established the mathematical model of hydrogel in fiber width,scaffold layer height and porosity.The flow velocity,wall shear stress and extrusion swell of the fluid were analyzed by means of numerical simulation,which provided theoretical support and guidance for the optimization of printing parameters.(3)Skin tissue engineering scaffold design and printing.According to the structural characteristics of human skin,we designed a three-dimensional model of the skin scaffold.The printing algorithm includes feature recognition,intersection computation,region grouping,path filling,etc.Finally,we print out the 3D scaffolds with different structural parameters by ACSPL+ language.(4)Cell printing and three-dimensional cell culture.We selected skin fibroblasts as seed cells and analyzed the activity of the cells after printing and in culture.Then,we observed the growth,proliferation and migration of fibroblasts in the three-dimensional scaffolds of hydrogel.A skin repair experiment was also carried out in mice using the printed skin scaffold and satisfactory results were achieved.