Abstract
The progress in the field of tissue engineering and clinical surgery demands further investigation of the correlation between mechanically exposed proteins of the extracellular matrix and the mechanical properties of macro-specimen. For example, a piece of tissue is often transferred between different locations or species and not only biological but also mechanical issues have to be concerned (different pressure, thickness, density, etc.).
This paper discusses the microscopic method for the type I collagen and elastin fiber identification that effectively supports and explains biomechanical results. The examined object was vena saphena magna that is used for coronary artery bypass graft surgery.
It has to be noted that the conditions in the venous and artery system differ significantly. The adopted mechanical testing was the inflation-extension test.
The initial longitudinal prestrain was induced in the tubular specimen of vena saphena magna and then inflated four times up to the pressure 4 kPa (vein pressure) and then four times up to the 16 kPa (systolic pressure). The longitudinal and circumferential deformations of the tube were evaluated using the edge detection method.
The second part of the same vein was immediately visualized for type I collagen by backward nondescanned second harmonic generation imaging (excitation at 860 nm by IR pulse laser, detection at 430+-10 nm) and elastin by twophoton excited autoflorescence (excitation at 860 nm by IR pulse laser, detection at 620+-40 nm) that enabled one to observe both proteins at the same depth. The result of the inflation-extension tests and the findings obtained during label-free optical imaging that requires little specimen processing for visualization of the mechanically most significant proteins, promises better understanding of the micro macro mechanical relationships.