Foetal hepatocyte transplantation in a vascularized AV-Loop transplantation model in the rat

The use of foetal liver cells (FLC) in the context of hepatic tissue engineering might permit efficient in vitro expansion and cryopreservation in a cell bank. A prerequisite for successful application of bioartificial liver tissue is sufficient initial vascularization. In this study, we evaluated the transplantation of fibrin gel‐immobilized FLC in a vascularized arterio‐veno‐venous (AV)‐loop model. FLC were isolated from embryonic/foetal (ED 16) rat livers and were enriched by using magnetic cell sorting (MACS). After cryopreservation, FLC were labelled by pkh‐26. Cells were transplanted in a fibrin matrix into a subcutaneous chamber containing a microsurgically created AV‐loop in the femoral region of the recipient rat. The chambers were explanted after 14 days. Subcutaneous implants without an AV‐loop and cell‐free implants served as controls. Fluorescence microscopy of the constructs was used to identify pkh‐26+‐ donor cells. Characterization was performed by RT‐PCR and immunhistology (IH) for CK‐18 and CD31. Transplantation of FLC using the AV‐loop permitted a neo‐tissue formation in the fibrin matrix. A high‐density vascularization was observed in the AV‐loop constructs as shown by CD31 IH. Viable foetal donor cells were detected which expressed CK‐18. FLC can be successfully used for heterotopic transplantation. Fibrin matrix permits rapid blood vessel ingrowth from the AV‐loop and supports engraftment of FLC. It is therefore an appropriate environment for hepatocyte transplantation in combination with microsurgical vascularization strategies. Transplantation of fibrin gel‐immobilized FLC may be a promising approach for the development of highly vascularized in vivo tissue‐engineering‐based liver support systems.