Quantitative analysis of cyanogen bromide-cleaved peptides for the assessment of type I: type II collagen ratios in equine articular repair tissue.

This research investigates a method to measure the ratios of Type I to Type II collagen in horse repair tissue using cyanogen bromide and a densitometric scanning process. The study also outlines how this method successfully indicated the absence of Type II collagen in repair tissue after an injury in ponies.

Methodology

• Researchers used cyanogen bromide to dissolve and fragment purified equine Type I and II collagen and equine articular surface repair tissue.
• The fragmented peptides were then segregated using a sodium dodecyl sulphate-polyacrylamide gel electrophoresis process.
• The densities of the separated peptides were scanned and measured, producing quantifiable data.

Assessing Collagen Ratios

• By examining the relative amounts of the peptides alpha 2(I) CB3, 5 and alpha 1(II)CB10, the method provided a precise way of determining Type I to Type II collagen ratios in mixtures of purified equine collagens.
• This technique proved sensitive enough to identify as low as 6% Type II collagen, once the band areas were corrected for peptide molecular weight and the number of chains in the parent tropocollagen molecule containing that particular peptide.

Application on Repair Tissue

• The research also involved applying this process to examine repair tissue from full-thickness osteochondral defects (a type of joint damage) in the dorso-distal margins (the upper, rear edge) of the intermediate carpal bones (the middle bones of the wrist) in ponies.
• The results demonstrated that the repair tissue did not contain noticeable amounts of Type II collagen 11 weeks after the defect was induced, providing useful insight into collagen change during the healing process.