Skeletal muscle tissue engineering provides a powerful platform for studying muscle regeneration, yet most in vitro models omit fibroadipogenic progenitors (FAPs), which are critical regulators of myogenic differentiation and extracellular matrix organization. We hypothesized that incorporating FAPs into 3D engineered muscle tissues (EMTs) would enhance functional maturation and produce divergent contractile outcomes in healthy versus Duchenne muscular dystrophy (DMD) models, where dystrophin deficiency reduces force generation and increases susceptibility to damage.
EMTs were generated from iPSC-derived myoblasts harboring a DMD-causing mutation and their isogenic controls (WT) using the Mantarray platform (Curi Bio). Constructs contained myoblasts, fibroblasts (~10%), and FAPs (0–16%), with myoblast content adjusted to maintain constant total cell density. Tissues were cultured to Day 25, and twitch and tetanic forces were assessed every two days with electrical stimulation.
Across all timepoints, FAP inclusion significantly increased contractile function in WT EMTs relative to 0% FAP controls. By day 25, WT twitch forces were 25% higher with 5% FAPs and 91% higher with 16% FAPs (p < 0.01). In contrast, FAP incorporation into DMD EMTs produced markedly attenuated increases in force, and no statistically significant differences were observed at Day 25. These results demonstrate that FAP co-culture drives dose-dependently contractility improvements in healthy EMTs, while dystrophin deficiency limits the functional influence of FAPs in DMD tissues. This work highlights the importance of incorporating interstitial cell populations into engineered muscle systems and establishes a tractable human platform for dissecting cell–cell interactions underlying dystrophic muscle physiology and therapeutic response.