Localization of mRNA of procollagen alpha 1 type I in torn supraspinatus tendons. In situ hybridization using digoxigenin labeled oligonucleotide probe.

A tendon is predominantly composed of collagen Type I. To determine the synthesis of collagen Type I after a rotator cuff tear, an in situ hybridization technique was applied to localize cells containing procollagen alpha 1 Type I in the proximal stump of five torn supraspinatus tendons obtained during surgery. Specimens were fixed in 10% buffered formalin, embedded in paraffin, and sectioned at 6 microns. A 22 mer oligonucleotide corresponding to a sequence coding a part of human procollagen alpha 1 Type I messenger RNA (mRNA) was used as a hybridization probe. The probe was 3'-end labeled with digoxigenin-11-dUTP, and the probe-mRNA hybrids were enzymatically visualized using conventional chromogens for alkaline phosphatase. The procollagen alpha 1 type I mRNA was clearly observed in the cells near the margin of the tear. However, they were not consistently found in the vicinity of the intratendinous extension of the tear and in cells of the subacromial bursa. It is concluded that this method should be used to study the characteristics of collagen synthesis in a torn rotator cuff tendon.