Fourier transform infrared spectroscopic analysis of normal and torn rotator-cuff tendons

Abstract

We have used Fourier transform infrared spectroscopy (FTIR) to characterise the chemical and structural composition of the tendons of the rotator cuff and to identify structural differences among anatomically distinct tears. Such information may help to identify biomarkers of tears and to provide insight into the rates of healing of different sizes of tear. The infrared spectra of 81 partial, small, medium, large and massive tears were measured using FTIR and compared with 11 uninjured control tendons. All the spectra were classified using standard techniques of multivariate analysis. FTIR readily differentiates between normal and torn tendons, and different sizes of tear. We identified the key discriminating molecules and spectra altered in torn tendons to be carbohydrates/phospholipids (1030 cm(-1) to 1200 cm(-1)), collagen (1300 cm(-1) to 1700 cm(-1) and 3000 cm(-1) to 3350 cm(-1)) and lipids (2800 cm(-1) to 3000 cm(-1)). Our study has shown that FTIR spectroscopy can identify tears of the rotator cuff of varying size based upon distinguishable chemical and structural features. The onset of a tear is mainly associated with altered structural arrangements of collagen, with changes in lipids and carbohydrates. The approach described is rapid and has the potential to be used peri-operatively to determine the quality of the tendon and the extent of the disease, thus guiding surgical repair.

A quantitative label-free analysis of the extracellular proteome of human supraspinatus tendon reveals damage to the pericellular and elastic fibre niches in torn and aged tissue

“…A clear downregulation of collagens has been previously described in torn supraspinatus tendon [22–24] and in particular a significant reduction in the abundance of both of the subunits of collagen I. Moreover, a significantly lower abundance of cartilage oligomeric matrix protein (COMP) was measured in torn samples.…”

“…This is an interesting issue, and a recent systematic review of the literature has made a claim that the expression of collagen III is increased in tendinopathy [12]. Although this claim is well supported by transcriptome data [28–31], protein evaluation directly from torn supraspinatus has resulted in mixed results, with one study showing an increase in the ratio of collagen III to collagen I [23] and another a reduction in both collagens [24]. This calls for some consideration of the possibly significant differences between transcriptome and proteome data, with processes such as degradation or the presence of complex post-transcriptional regulation pathways affecting the actual composition of the tissue.…”

Distribution and expression of type VI collagen and elastic fibers in human rotator cuff tendon tears

“…Alterations in pre-existing molecular components within tissue, such as proteoglycans and collagens, play a crucial role in rotator cuff tear pathology (31,32). The ratio of type III to type I collagen is an important indicator of tendon healing potential, with higher expression of type III collagen during injury associated with improved prognosis (33,34).…”

Proteomics Perspectives in Rotator Cuff Research: A Systematic Review of Gene Expression and Protein Composition in Human Tendinopathy

“…An increased expression of collagen III was related to tendinopathy including tears in all[40, 46, 53, 64, 66, 69, 70, 73, 74, 79, 86, 116] but 2[33, 38] of 45 included studies, which examined this protein. This change was evident both with respect to gene expression, i.e.…”