Background: Hydrogels are widely used as ECM-mimetic biomaterials, but most lack the nanofibrous hierarchy of the native extracellular matrix, which is essential for regulating human stem cells (hSCs) behavior. Nanofibrous composite hydrogels address this limitation by incorporating fibrillar cues, either intrinsically formed, dispersed within the matrix, or applied at the surface, to better replicate the structural and mechanotopographical features of the stem cell niche. Summary: This review systematically compares three nanofiber hydrogel architectures: self-assembling nanofiber matrices, hydrogels with encapsulated electrospun fibers, and hydrogels surface-decorated with fibrous coatings. We examine how differences in fiber chemistry, stiffness, degradability, and spatial organization regulate key hSCs' behaviors, including adhesion, viability, morphology, proliferation, migration, differentiation, and secretion. Polymeric, natural, hybrid, magnetic, and bioactive nanoparticle reinforced fibers are each discussed to highlight how each configuration generates distinct biophysical and biochemical cues. By linking fabrication strategies to resulting cellular outcomes, this review outlines architecture-specific advantages and limitations that inform the rational design of next-generation ECM-mimetic scaffolds. Key Messages: Nanofibrous hydrogels bridge the gap between conventional hydrogel mechanics and the nanoscale organization of the native ECM, enabling more physiologically relevant control of hSCs' behavior. Each architecture provides distinct structural and mechanobiological cues suited to different therapeutic or manufacturing goals. Hybrid and multifunctional fiber systems, such as magnetic systems, ion-releasing platforms, and nanoparticle-enhanced fibers, deliver synergistic biochemical and mechanical signals that enhance differentiation and paracrine activity. Understanding how fiber properties and organization influence cell responses provides a roadmap for designing ECM-mimetic biomaterials optimized for scalable hSCs expansion and regenerative applications.
Roca-Arroyo et al. (2026) studied this question.