Firefly rats as an organ/cellular source for long-term in vivo bioluminescent imaging

Transplantation research involving the use of stem cells demands an appropriate in vivo visualization system to monitor cellular fate over an observation period. The new field of in vivo imaging is being developed with fluorescent and luminescent biotechnology, and involves the real-time visualization of complex cellular processes in living animals. : Following our recent development of inbred green fluorescent protein (GFP)-transgenic (Tg) rats, we created the establishment of inbred (Lewis) Tg rats with firefly luciferase. The immunogenicity against luciferase was evaluated by the skin grafting test, and the fate of grafts was monitored by in vivo luminescent technique. : The luciferase-Tg rats ubiquitously expressed the marker gene. Conventional skin grafting apparently showed the long-term acceptance of luciferase-Tg rat skin on wild-type rats (>100 days), compared with grafting of GFP-Tg-derived skin (