Development and evaluation of techniques based on second harmonic generation microscopy to quantify the collagen matrix in cartilage

Abstract

Cartilage diseases are prevalent, and intense effort is targeted to improving treatment for conditions such as osteoarthritis and traumatic cartilage injury. Collagen is one of the main structural components of cartilage, providing tensile stiffness and strength. Changes in collagen integrity are associated with most cartilage pathologies, and assessment of the collagen matrix is therefore highly relevant within the field of cartilage research. Second harmonic generation (SHG) microscopy provides a method for label free evaluation of the collagen matrix.

The purpose of this thesis has been to create, inspect and evolve tools to quantify the collagen matrix in cartilage based on SHG microscopy. This overall aim has been subdivided into three subaims to address various aspects of the SHG signal:

1. Image analysis. Using the spatial frequencies of the second harmonic signal to quantify the orientation of collagen fibrils. 2. Intensity analysis. Using the intensity of SHG together with a suitable reference to assess collagen density. 3. Polarization-resolved SHG (P-SHG). Using the polarization dependent response of the SHG signal to extract more information about collagen type and orientation.