Development of Muscle Tendon Junction in vitro Using Aligned Electrospun PCL Fibres

This study developed an in vitro muscle–tendon junction (MTJ) model using aligned electrospun polycaprolactone (PCL) fiber scaffolds to assess how cyclic tensile strain and muscle–tendon co-culture regulate MTJ-associated markers. Aligned PCL fibers were produced using a gap-collector electrospinning setup and collagen-coated to enhance cell adhesion. Human myoblasts and tenocytes were seeded on opposite sides of the same aligned fiber strip to create an interface model and cultured for 7 or 14 days with or without cyclic strain. Cyclic strain (10%,1 Hz) increased fiber alignment and significantly increased cell alignment relative to unstrained controls, and prolonged cyclic strain increased cell elongation (aspect ratio) at day 14. MTJ marker gene expression (COL22,PAX,TAL) was upregulated most strongly under combined co-culture plus cyclic strain, with COL22 and PAX significantly increased by day 7 and TAL increased by day 14. Immunofluorescence and quantitative mean fluorescence intensity analysis showed markedly higher collagen 22 and paxillin protein production under strained co-culture conditions (largest effects at day 14), and co-culture under strain produced higher MTJ-marker protein levels than strained mono-cultures. Overall, the data indicate that cyclic strain and muscle–tendon co-culture synergize to promote MTJ-like molecular signatures on aligned electrospun scaffolds.