Effect of a hydro gel elasticity for transplantation assist device of the myocardial cell sheets

Recently the myocardial cell sheet is applied for cure of the heart failure. To develop a new device for transplanting the cell sheet is needed. Authors have evaluated a stamp-type device. Gelatin hydro gel as an adhesive material is used between the device and the cell sheet. Requirements of the gelatin hydro gel are to deform, during removal from surface of the device and to fit the round surface of the heart. These are related with the viscoelasticity of the gelatin gel and it is important to understand its features. The purpose of this study is 1) to measure the viscoelasticity of the gelatin hydro gel under various manufacturing conditions, and 2) to clarify the effect of the gel elasticity on the exfoliation from the device. The reaction force needed to push the gelatin hydro gel by a column (diameter of 12.7 mm) was fitted with a standard linear Kelvin model. Viscoelastic properties of the Kelvin model increased according to the cooling period and the concentration of the gelatin powder. Maximum deformation before exfoliation was compared between 7.5 % and 15 % of concentration of the gelatin powder. Higher elasticity of the gelatin hydro gel resulted in smaller deformation before exfoliation.