Prediction of heat-induced collagen shrinkage by use of second harmonic generation microscopy

Abstract

Collagen shrinkage associated with denaturation from thermal treatment has a number of important clinical applications. However, individualized treatment is hindered by the lack of reliable noninvasive methods to monitor the process of collagen denaturation. We investigate the serial changes of collagen denaturation from thermal treatment of rat tail tendons at 58 degrees C by use of second harmonic generation (SHG) microscopy. We find that rat tail tendon shrinks progressively from 0 to 9 min of thermal treatment, and remains unchanged in length upon further thermal treatment. The SHG intensity also decreases from 0 to 9 min of thermal treatment and becomes barely detectable from further thermal treatment. Collagen shrinkage and the SHG intensity are well correlated in a linear model. In addition, SHG imaging reveals a tiger-tail-like pattern of collagen denaturation. The bands of denatured collagen progressively widen from increased thermal treatment and completely replace the adjacent bands of normal collagen after 9 min of thermal treatment. Our results show that collagen denaturation in rat tail tendon from thermal treatment is inhomogeneous, and that SHG intensity can be used to predict the degree of thermally induced collagen shrinkage. With additional development, this approach has the potential to be used in biomedical applications.

Characterization of type I, III and V collagens in high-density cultured tenocytes by triple-immunofluorescence technique

“…As a result of repeated movement and degeneration which occurs in the course of time, tendons are functionally open to traumas which can come into existence in both acute and chronic ways (Lin et al 2006). In recent time, trauma which occurs in sportsman is very common.…”

“…Among these, implantation therapies of tenocytes used in the regeneration of tendon injuries are quite important. As a result of repeated movement and degeneration which occur in the course of time, tendons are functionally open to traumas which can come into existence in both acute and chronic ways (Lin et al 2006). In order to solve this problem, several tissue engineers have produced tenocytes which are buried into biopolymers and autologous mesenchymal cells originating from different tissues such as bone marrow (Cao et al 1994;Awad et al 1995;Koob et al 2001).…”

Biothermomechanical behavior of skin tissue

“…Different metrics have been used to characterize the thermal denaturation and heating-induced damage of collagen and collagenous tissues including biological metrics such as enzyme deactivation [160] and extravasation of fluorescenttagged plasma proteins [161], thermal metrics such as changes in enthalpy [162,163], mechanical metrics such as thermal shrinkage [8,158,164,165], and optical metrics such as thermally induced loss of birefringence [166][167][168][169]. Although the shrinkage of collagen due to thermal denaturation have been widely used and suggested to be used as a convenient continuum metric of thermal damage [150,170], Wells et al [171] point out that equilibrium shrinkage may not be a universal metric to measure thermal damage.…”

Multiphotonentomographie

“…Prokollagen oder denaturiertes Kollagen führt dagegen nicht zu einem SHG-Signal, sodass auch thermische Belastungen im Rahmen von Traumata oder Lasertherapien untersucht werden können [53,78].…”