Quantitation of type I to type III collagen ratios in small samples of human tendon, blood vessels, and atherosclerotic plaque.

A method is described whereby the ratio of the major interstitial collagens (Types I and III) can be measured in biopsy specimens of human tissue weighing as little as 25 mg. Marker peptides are solubilized from the tissue by digestion with cyanogen bromide. These peptides which are not known to be involved in collagen crosslinking are isolated and quantified by a combination of carboxymethyl-cellulose chromatography and polyacrylamide gel electrophoresis. The peptides used are alpha 1(I)-CB7 and alpha 1(III)-CB5. The use of the method is illustrated by analyzing the collagen type ratio in small specimens of tendon, aorta, and vena cava.