Mechanism-guided nano and advanced biomaterials for intrauterine adhesions: from pathological microenvironment modulation to functional endometrial regeneration

Intrauterine adhesions arise from failed endometrial repair, in which wound apposition, maladaptive immune–stromal signaling, oxidative injury, fibrotic remodeling and loss of regenerative niches impair reproductive function. This critical narrative review organizes nano and advanced biomaterials around six overlapping biological repair requirements and examines how material structure influences interfacial behavior, mechanics, transport and local exposure. Study-level comparisons distinguish treatment timing, component controls, measured release or residence, and reproductive outcomes. Spatially asymmetric interfaces, stimulus-responsive networks and sequential delivery are evaluated as different design principles; differential release alone does not establish repair-stage matching. Nanoscale structure is also distinguished from evidence that a particular nanoscale feature causes therapeutic benefit. Human evidence is most developed for relatively simple barriers and selected cell–scaffold strategies, whereas catalytic, EV-containing and responsive systems remain predominantly preclinical. We propose minimum sufficient material complexity as a comparison principle: each added component should address a defined unmet function and demonstrate an increment over an indication-relevant simpler approach. Functional recovery requires coordinated hormonal, epithelial, stromal and vascular behavior, with pregnancy outcomes interpreted alongside product fate and reproductive safety.