Matrix Metalloproteinase Response to Acute Resistance Exercise is Altered in Osteoarthritic Adults with Increased Muscle Collagen and PDGFRα+ Mesenchymal Cells

Background: Knee osteoarthritis (OA) is linked to weakened knee extensors, changes in muscle fibers, a decrease in satellite cell numbers, and an increase in collagen buildup in the vastus lateralis (VL). The cause of this collagen buildup and its connection to weaker knee extensor strength is still unclear. Satellite cells and PDGFR+ mesenchymal cells in the body also produce collagen and enzymes that break down collagen.

This study aimed to examine the impact of acute resistance exercise on knee extensor function, muscle fiber structure, satellite cells, PDGFR+ mesenchymal cells, and collagen remodeling in individuals with and without moderate-to-severe knee OA.

Methods: The study involved volunteers with and without moderate-to-severe knee OA. All participants underwent a muscle biopsy to assess resting muscle tissue. Following this, they performed an acute bout of resistance exercise and had another biopsy 72 hours later. Knee extensor strength was measured using a Biodex dynamometer.

In VL samples, researchers assessed MMP gene expression (qPCR), protein area fraction (immunofluorescence), and enzyme activity (zymography). Additionally, they examined PDGFR+ mesenchymal cells, satellite cells, their interaction with MMP9, and muscle fiber structure through immunofluorescence. Fibrillar muscle collagen content was quantified using picrosirius red.