Preparation Of EGF Releasing Porous Pectin/Alginate/Heparin Scaffolds For Liver Tissue Engineering

In this thesis, we developed a new complex porous controlled release system which was consisted of pectin, alginate, heparin and EGF, providing a synthetic controlled release matrix for liver tissue engineering. As a new synthetic extracellular matrix for hepatocytes, a series of scaffolds were fabricated with pectin (P), alginate (AL) and heparin (H) through lyophilization. The compositions of the scaffolds were characterized by IR. Porosity and porous distribution were observed by SEM. And the mechanical properties were determined by testing machine. The results showed that this matrix has open pores, high porosity (>90%) and improved mechanical properties.Then we incorporated EGF into the pectin/alginate/heparin scaffold by simple dipping method. The release behaviors of EGF were tested by ELISA. The results showed that compared to pectin/alginate/EGF scaffold, the scaffold containing heparin can be released out EGF in a more sustained manner with a constant release rate of 6ng/ml/day for more than 16 days. This is very important to maintain the growth and the liver specific functions of the hepatocytes for long time culture.Then we ingrafted hepatocytes into this new matrix and the liver specific function was determined by urea synthesis and albumin secretion. Compared to the pectin and alginate scaffolds, the pectin/alginate complex scaffold facilitated the adhesion and growth of hepatocytes and improved the liver function. Compared to pectin/alginate/EGF scaffold, the scaffold containing heparin released EGF in a more sustained manner, thus further increased the specific liver function to be more available for a long time culture. These results suggested that this new controlled release system of EGF enhanced the specific liver function effectively to be a new synthetic ECM for bioartificial liver (BAL) devices.