Hepatic targeting of transplanted liver sinusoidal endothelial cells in intact mice

Targeting of cells to specific tissues is critical for cell therapy. To study endothelial cell targeting, we isolated mouse liver sinusoidal endothelial cells (LSEC) and examined cell biodistributions in animals. To identify transplanted LSEC in tissues, we labeled cells metabolically with DiI-conjugated cetylated low density lipoprotein particles (DiI-Ac-LDL) or (111)Indium-oxine, used LSEC from Rosa26 donors expressing beta-galactosidase or Tie-2-GFP donors with green fluorescent protein (GFP) expression, and tranduced ILSEC with a GFP-lentiviral vector. LSEC efficiently incorporated (111)Indium and DiI-Ac-LDL and expressed GFP introduced by the lentiviral vector. Use of radiolabeled ISEC showed differences in cell biodistributions in relation to the cell transplantation route. After intraportal injection, LSEC were largely in the liver (60 +/- 13%) and, after systemic intravenous injection, in lungs (67 +/- 9%); however, after intrasplenic injection, only some LSEC remained in the spleen (29 +/- 10%; P < .01 ), whereas most ISEC migrated to the liver or lungs. Transplanted I-SEC were found in the liver, lungs, and spleen shortly after transplantation, whereas longer-term cell survival was observed only in the liver. Transplanted ILSEC were distinct from Kupfler cells with expression of Tie-2 promoter-driven GFP and of CD31, without F4/80 reactivity. In further studies using radiolabeled ILSEC, we established that the manipulation of receptor-mediated cell adhesion in liver sinusoids or the manipulation of blood flow- dependent cell exit from sinusoids improved intrahepatic retention of LSEC to 89 +/- 7% and 89 +/- 5 %, respectively (P < .01). In conclusion, the targeting of ILSEC to the liver and other organs is directed by vascular bed-specific mechanisms, including blood flow-related processes, and cell-specific factors. These findings may facilitate analysis of ILSEC for cell and gene therapy applications.