Adult human and rat pancreas stem cells as well as tumor spheroids were irradiated with femtosecond laser pulses in the near infrared (NIR) spectral range at high transient GW/cm² and TW/cm² intensities. The cellular response to the laser exposure was probed by the detection of modifications of NAD(P)H autofluorescence, the formation of reactive oxygen species (ROS) and DNA strand breaks (TUNEL-assay), and viability (live/dead test). The results confirm that long-term scanning of stem cells can be performed at appropriate laser exposure parameters without a measurable impact on the cellular metabolism and vitality. In addition, it was proven that a targeted inactivation of a particular single stem cells or a single tumour cell inside a 3D cell cluster using single point illumination at TW/cm² laser intensities can be performed without affecting neighbouring cells. Therefore multiphoton microscopes can be considered as biosafe tools for long-term analysis of stem cells as well as highly precise optical knocking out of single cells within cell clusters and tissues.

Date Published: 10 February 2007
PDF: 5 pages
Proc. SPIE 6442, Multiphoton Microscopy in the Biomedical Sciences VII, 64421Z (10 February 2007); doi: 10.1117/12.702586

Published in SPIE Proceedings Vol. 6442:
Multiphoton Microscopy in the Biomedical Sciences VII
Ammasi Periasamy; Peter T. C. So, Editor(s)