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Imaging leukocyte trafficking in vivo with two-photon-excited endogenous tryptophan fluorescence.

Li C, Pastila RK, Pitsillides C, Runnels JM, Puoris'haag M, Côté D, Lin CP - Opt Express (2010)

Bottom Line: We describe a new method for imaging leukocytes in vivo by exciting the endogenous protein fluorescence in the ultraviolet (UV) spectral region where tryptophan is the major fluorophore.Two-photon excitation near 590 nm allows noninvasive optical sectioning through the epidermal cell layers into the dermis of mouse skin, where leukocytes can be observed by video-rate microscopy to interact dynamically with the dermal vascular endothelium.Because the new method alleviates the need to introduce exogenous labels, it is potentially applicable for tracking leukocytes and monitoring inflammatory cellular reactions in humans.

View Article: PubMed Central - PubMed

Affiliation: Wellman Center for Photomedicine and Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA. Li.Chunqiang@mgh.harvard.edu

ABSTRACT
We describe a new method for imaging leukocytes in vivo by exciting the endogenous protein fluorescence in the ultraviolet (UV) spectral region where tryptophan is the major fluorophore. Two-photon excitation near 590 nm allows noninvasive optical sectioning through the epidermal cell layers into the dermis of mouse skin, where leukocytes can be observed by video-rate microscopy to interact dynamically with the dermal vascular endothelium. Inflammation significantly enhances leukocyte rolling, adhesion, and tissue infiltration. After exiting the vasculature, leukocytes continue to move actively in tissue as observed by time-lapse microscopy, and are distinguishable from resident autofluorescent cells that are not motile. Because the new method alleviates the need to introduce exogenous labels, it is potentially applicable for tracking leukocytes and monitoring inflammatory cellular reactions in humans.

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(a-c) Tryptophan fluorescence images of BALB/c mouse ear (a) 0-h, and (b & c) 24-h post LPS injection (scale bar 50 µm).
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g006: (a-c) Tryptophan fluorescence images of BALB/c mouse ear (a) 0-h, and (b & c) 24-h post LPS injection (scale bar 50 µm).

Mentions: The trafficking of leukocytes is greatly enhanced during inflammation. Leukocyte recruitment out of blood vessels and into tissues is essential for both the development of an appropriate inflammatory response to injury or infection and the debilitating sequence of events leading to inflammatory disorders such as asthma and allergy. We first induced inflammation by subcutaneous injection of 5 µg of lipopolysaccharide (LPS) into the mouse ear pinna close to its base. LPS is a prototypical endotoxin that promotes the secretion of pro-inflammatory cytokines that help to recruit leukocytes. Figure 6Fig. 6


Imaging leukocyte trafficking in vivo with two-photon-excited endogenous tryptophan fluorescence.

Li C, Pastila RK, Pitsillides C, Runnels JM, Puoris'haag M, Côté D, Lin CP - Opt Express (2010)

(a-c) Tryptophan fluorescence images of BALB/c mouse ear (a) 0-h, and (b & c) 24-h post LPS injection (scale bar 50 µm).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369551&req=5

g006: (a-c) Tryptophan fluorescence images of BALB/c mouse ear (a) 0-h, and (b & c) 24-h post LPS injection (scale bar 50 µm).
Mentions: The trafficking of leukocytes is greatly enhanced during inflammation. Leukocyte recruitment out of blood vessels and into tissues is essential for both the development of an appropriate inflammatory response to injury or infection and the debilitating sequence of events leading to inflammatory disorders such as asthma and allergy. We first induced inflammation by subcutaneous injection of 5 µg of lipopolysaccharide (LPS) into the mouse ear pinna close to its base. LPS is a prototypical endotoxin that promotes the secretion of pro-inflammatory cytokines that help to recruit leukocytes. Figure 6Fig. 6

Bottom Line: We describe a new method for imaging leukocytes in vivo by exciting the endogenous protein fluorescence in the ultraviolet (UV) spectral region where tryptophan is the major fluorophore.Two-photon excitation near 590 nm allows noninvasive optical sectioning through the epidermal cell layers into the dermis of mouse skin, where leukocytes can be observed by video-rate microscopy to interact dynamically with the dermal vascular endothelium.Because the new method alleviates the need to introduce exogenous labels, it is potentially applicable for tracking leukocytes and monitoring inflammatory cellular reactions in humans.

View Article: PubMed Central - PubMed

Affiliation: Wellman Center for Photomedicine and Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA. Li.Chunqiang@mgh.harvard.edu

ABSTRACT
We describe a new method for imaging leukocytes in vivo by exciting the endogenous protein fluorescence in the ultraviolet (UV) spectral region where tryptophan is the major fluorophore. Two-photon excitation near 590 nm allows noninvasive optical sectioning through the epidermal cell layers into the dermis of mouse skin, where leukocytes can be observed by video-rate microscopy to interact dynamically with the dermal vascular endothelium. Inflammation significantly enhances leukocyte rolling, adhesion, and tissue infiltration. After exiting the vasculature, leukocytes continue to move actively in tissue as observed by time-lapse microscopy, and are distinguishable from resident autofluorescent cells that are not motile. Because the new method alleviates the need to introduce exogenous labels, it is potentially applicable for tracking leukocytes and monitoring inflammatory cellular reactions in humans.

Show MeSH
Related in: MedlinePlus