Mesothelial Cell Regeneration in Purified Human Amnion Membrane Grafts Implanted in Dog Pericardium

Abstract

We prepared a complex membrane consisting of two collagen membranes purified from human amnion and a polyglycolic acid (PGA) mesh. Using this membrane, we produced two types of sheets for pericardial replacement by glutaraldehyde cross-linking followed by succinylation [PGA-amnion (GA-S) sheet] or by dehydrothermal cross-linking followed by hyaluronic acid fixation [PGA-amnion (DHT-H) sheet]. We used these sheets to replace part of the pericardium in dogs, and the state of pericardial repair and regeneration were evaluated. As a control sheet, expanded polytetrafluoroethylene (EPTFE) with a thickness of 0.1 mm was used. After implantation of the PGA-amnion (DHT-H) sheet, soft connective tissue with abundant capillaries was observed, and its surface was covered with a mesothelial cell layer with many microvilli. The basement membrane was nearly normal. After implantation of the PGA-amnion (GA-S) sheet, dense connective tissue was observed, and its surface was covered with mesothelial cells. However, there were only a few microvilli, and the basement membrane was incomplete. After implantation of the EPTFE sheet, only a multilayer structure of dense connective tissue was observed. The connective tissue was exposed without mesothelial cells on its surface. Thus, pericardial repair and regeneration were induced by implantation of a sheet produced by dehydrothermal cross-linking, which does not impair the chemical properties of collagen purified from human amnion.