Table 4 –

Techniques to prepare the liver to allow improved uptake and engraftment of cells.

Liver preconditioning
Irradiation	Low dose may improve cell engraftment and proliferation Suppresses phagocytic activity of Kupffer cells Optimal timing for transplant 1–7 days after radiation Long-term risk of fibrosis Low doses may be used for children
Portal embolization	Reversible with absorbable material Ischemia/reperfusion injury stimulates the regenerative response Can cause transient increased in portal pressure and mild inflammatory reaction Replacement of up to 10% of liver mass with donor cells has been demonstrated
Microbeads	Nonselective embolization of distal presinusoidal vessels Induces regenerative signals and spares significant liver parenchyma Major obstruction and hemorrhage can potentially lead to acute liver failure and death Animal studies only
Ischemic preconditioning	Short period of ischemia followed by a brief period of reperfusion before planned insult The brief reperfusion period stimulates protective mechanisms against repetitive stress Clinical application has not been performed with hepatic cell transplants
Chemical therapy	Various agents accelerate and increase entry into liver sinusoids and engraftment in the parenchyma Numerous side effects make these options ill-suited for clinical application