Intravital imaging of fluorescent markers and FRET probes by DNA tattooing.
BACKGROUND
Advances in fluorescence microscopy and mouse transgenesis have made it possible to image molecular events in living animals. However, the generation of transgenic mice is a lengthy process and intravital imaging requires specialized knowledge and equipment. Here, we report a rapid and undemanding intravital imaging method using generally available equipment.


RESULTS
By DNA tattooing we transfect keratinocytes of living mice with DNA encoding fluorescent biosensors. Subsequently, the behavior of individual cells expressing these biosensors can be visualized within hours and using conventional microscopy equipment. Using this "instant transgenic" model in combination with a corrected coordinate system, we followed the in vivo behavior of individual cells expressing either FRET- or location-based biosensors for several days. The utility of this approach was demonstrated by assessment of in vivo caspase-3 activation upon induction of apoptosis.


CONCLUSIONS
This "instant skin transgenic" model can be used to follow the in vivo behavior of individual cells expressing either FRET- or location-based probes for several days after tattooing and provides a rapid and inexpensive method for intravital imaging in murine skin.
Bins
Adriaan D
AD
Department of Immunology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands. a.bins@nki.nl <a.bins@nki.nl>
van Rheenen
Jacco
J
Jalink
Kees
K
Halstead
Jonathan R
JR
Divecha
Nullin
N
Spencer
David M
DM
Haanen
John B A G
JB
Schumacher
Ton N M
TN
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D053148:Caspase 3 / Q000378:metabolism*; D002478:Cells, Cultured; D015342:DNA Probes; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes; D015603:Keratinocytes / Q000166:cytology / Q000201:enzymology*; D051379:Mice; D008856:Microscopy, Fluorescence / Q000379:methods; D015336:Molecular Probe Techniques; D014162:Transfection / Q000379:methods*
D015342:DNA Probes; D005456:Fluorescent Dyes; D053148:Caspase 3