Transplantation of engineered chimeric liver with autologous hepatocytes and xenobiotic scaffold.

OBJECTIVE

Generation of human livers in pigs might improve the serious shortage of grafts for human liver transplantation, and enable liver transplantation without the need for deceased or living donors. We developed a chimeric liver (CL) by repopulation of rat hepatocytes in a mouse and successfully transplanted it into a rat recipient with vessel reconstruction. This study was designed to investigate the feasibility of CL for supporting the recipient after auxiliary liver grafting.

METHODS

Hepatocytes from luciferase transgenic or luciferase/LacZ double-transgenic rats were transplanted into 20- to 30-day-old urokinase-type plasminogen activator/severe-combined immunodeficiency (uPA/SCID) mice (n = 40) to create CLs with rat-origin hepatocytes. After replacement of mouse hepatocytes with those from rats, the CLs were transplanted into wild-type Lewis (n = 30) and analbuminemia (n = 10) rats, followed by immunosuppression using tacrolimus (TAC) with/without cyclophosphamide (CPA) or no immunosuppression. Organ viability was traced by in vivo bioimaging and Doppler ultrasonography in the recipient rats for 4 to 6 months. Rat albumin production was also evaluated in the analbuminemia rats for 4 months. In addition, histological analyses including Ki67 proliferation staining were performed in some recipients.

RESULTS

Both immunosuppressive protocols significantly improved graft survival and histological rejection of CLs as compared to the nonimmunosuppressed group. Although rat albumin production was maintained in the recipients for 4 months after transplantation, ultrasonography revealed patent circulation in the grafts for 6 months. Ki67 staining analysis also revealed the regenerative potential of CLs after a hepatectomy of the host native liver, whereas immune reactions still remained in the mouse-origin structures.

CONCLUSIONS

This is the first report showing that engineered CLs have potential as alternative grafts to replace the use of grafts from human donors.