The Delayed Presentation of Achilles Tendon Ruptures Is Associated With Marked Alterations in the Gene Expression of COL1A1, MMPs, TIMPs, and IL-6

Abstract

Background: Both acute and chronic Achilles tendon ruptures are affected by alterations in the extracellular matrix during the healing process of the tendon. Yet, these alterations in gene expression patterns are not well characterized. Purpose: To characterize temporal and spatial differences in gene expression patterns after an Achilles tendon rupture and to evaluate if cells from chronic Achilles tendon ruptures have the same ability to form new tendon tissue (tendon constructs) as healthy tendon cells. Study Design: Controlled laboratory study. Methods: A total of 35 patients with surgically treated Achilles tendon ruptures were included in the study and divided into 3 groups: acute (<4 weeks), short-term chronic (1-6 months), and long-term chronic (>6 months). Biopsy specimens were collected during surgical repair and were used to analyze the gene expression within the different groups and to compare mRNA levels in the proximal and distal tendon ends. A complementary in vitro experiment was performed to evaluate if cells from chronic Achilles tendon ruptures can form tendon constructs. Results: The mRNA levels for COL1A1 and COL3A1 were significantly higher in the short-term chronic group compared with the acute group (P