Inhibition of endogenous TGF-β normalizes extracellular matrix deposition in hiPSC-derived fibroblasts

Fibroblasts are mesenchymal cells with essential functions for connective tissue homeostasis and repair through the production and organization of the extracellular matrix (ECM). Most reconstructed skin models used in research and skin-related applications rely on fibroblasts to produce ECM. Despite their shared functions, human fibroblasts from different origins exhibit heterogeneity in age, morphotype, and localization. Induced pluripotent stem cells (iPSCs) offer a promising alternative by providing a consistent and scalable source of fibroblasts, overcoming the challenges of availability and variability. Here, we show that iPSC-derived fibroblasts (F-hiPSC) exhibit enhanced proliferative capacity and substantial functional differences compared to primary fibroblasts. Our aim was thus to comprehensively characterize F-hiPSCs in terms of fibroblast marker expression to benchmark their subtype identity, phenotype and ECM production. Secretome analysis also revealed that both Transforming Growth Factor-beta (TGF-β) abundance and activity were strongly increased in F-hiPSC, thereby enhancing ECM production and collagen I biosynthesis and affecting the maturation and assembly of collagen I fibers. By inhibiting the main TGF-β signaling receptor, we also unraveled the potential of modulating TGF-β signaling to normalize F-hiPSC ECM production.