Epithelial tissues undergo fetal-like cellular reprogramming to regenerate after damage1,2. Although the mesenchyme and the extracellular matrix (ECM) play critical roles in tissue homeostasis and regeneration2–5, their role in repurposing developmental programs in epithelium is unknown. To model epithelial regeneration, we culture intestinal epithelium on decellularized small intestinal scaffold (iECM), and identify Asporin (Aspn), an ECM bound proteoglycan, as a critical mediator of cellular reprogramming. Aspn is produced by the mesenchyme, and we show that its effect on epithelial Tgfβ-signalling via CD44 is critical for fetal-like conversion. Furthermore, we demonstrate that Aspn is transiently increased upon chemotherapy-induced damage and pivotal for a timely induction of the fetal-like state and tissue regeneration. In summary, we establish a platform for modelling epithelial injury responses ex vivo, and show that the mesenchymal Aspn-producing niche controls tissue repair by regulating epithelial fetal-like reprogramming.
