Piceatannol enhances contractile force in 3D engineered skeletal muscle tissues

Abstract

Background: Skeletal muscle underpins movement, metabolic homeostasis, and overall health. Age- and disease-related declines in muscle function lead to disability and increased healthcare burden. Piceatannol (PIC), a polyphenol abundant in passion fruit seeds, has shown antioxidant and metabolic effects in muscle cells. However, its direct impact on contractile force remains unclear. Three-dimensional (3D) engineered skeletal muscle provides a physiologically relevant in vitro model that enables direct measurement of contractile force.

Objective: We investigated the effects of PIC on contractile force in 3D engineered skeletal muscle and the underlying molecular pathways.

Methods: 3D engineered tissues were generated from C2C12 myoblasts embedded in type I collagen and differentiated in serum-reduced medium. Constructs were treated with 50 or 100 µM PIC or vehicle. Contractile force was measured at baseline (pre-treatment) and at weeks 1 and 2 post-treatment using electrical pulse stimulation, by tracking displacement of flexible pillars. RNA-seq was performed on two-dimensional (2D) cultured myotubes to identify genes differentially expressed following PIC treatment, and key findings were validated by RT-qPCR.

Results: PIC increased contractile force relative to vehicle in the 3D skeletal muscle tissues. At 50 µM, contractile force was significantly higher than vehicle at week 2; at 100 µM, it was significantly higher at both weeks 1 and 2. Transcriptomic analysis revealed enrichment of pathways related to carbohydrate metabolism, particularly glycolysis and glucose handling. RT-qPCR confirmed increased expression of G/ut4 and glycolytic enzymes, including Hk2, Pfkm, and Pkm.

Conclusion: In 3D engineered skeletal muscle, PIC enhanced contractile force and upregulated genes related to glucose uptake and glycolysis. These preclinical findings support and inform the development of PIC-containing functional foods aimed at preserving muscle function.

Novelty of the Study: This study is the first to demonstrate, in a physiologically relevant 3D engineered skeletal muscle model that overcomes 2D culture limitations, that PIC increases contractile force measured directly. It further implicates glycolytic activation as the underlying mechanism.

Keywords: muscle function; contractile force; skeletal muscle; glycolysis; piceatannol; polyphenol; 3D engineered skeletal muscle tissues