Biomedical Engineering Reference
In-Depth Information
15
SHG Imaging of Collagen
and Application to Fibrosis
Quantization
15.1 Introduction ......................................................................................349
Collagenous Fibrosis: Biomedical Issues • SHG Imaging of Fibrillar
Collagens
15.2 Physical Origin of SHG Response from Collagen
and Specificity to Fibrillar Collagens ............................................350
Molecular Origin of Collagen Nonlinear Response • Building
the SHG Signal at Macromolecular Scale • Summary
15.3 Second-Harmonic Imaging of Tissue Fibrosis.............................353
Multiphoton Imaging of Lung, Kidney, and Liver
Fibrosis • Advantages of SHG Microscopy
15.4 Fibrosis Quantitative Scoring Using SHG Microscopy ..............359
Issues • Experimental Setup and Protocols • Image Processing
to Quantify Fibrosis Extent • Biomedical Applications
15.5 Discussion: Advantages and Limitations of SHG
Microscopy for Fibrosis Scoring.....................................................363
Comparison to Other Imaging Techniques • Perspectives, Possible
Improvements
15.6 Conclusion .........................................................................................366
Acknowledgments ........................................................................................366
References......................................................................................................366
Marie-Claire
Schanne-Klein
École Polytechnique
CNRS-Inserm
15.1 introduction
15.1.1 collagenous Fibrosis: Biomedical issues
Collagen is the most abundant protein in the extracellular matrix (ECM), and plays a central role in the
formation of fibrillar and microfibrillar networks, basement membranes, as well as other structures of
the connective tissue (Hulmes 2002). Many genetically distinct collagen types have been described so
far, and show different structures, functions, and distribution in tissues (Ricard-Blum and Ruggiero
2005). The characteristic feature of a collagen molecule is its long triple helical structure. Three polypep-
tide chains, called
α
chains and characterized by a (Gly-X-Y)
repeated structure, are wrapped around
one another in a ropelike right-handed superhelix (Beck and Brodsky 1998). The most abundant family
of collagens with more than 90% of the total collagen consists of the fibril-forming collagens: mainly
collagen I, II, III, V, and XI, whose helical domains are continuous over typically 1000 amino acids. They
are found in a wide variety of tissues such as bone, tendon, skin, ligament, cornea, and internal organs.
Once the procollagen molecules are secreted from the cells into the ECM, they are cleaved to collagen
349
