Microwell encapsulation scaffolds enable sustained paracrine cell therapy in limb ischaemia

Cell-based therapies for ischaemic diseases are increasingly understood to act through paracrine mechanisms rather than engraftment, but their clinical efficacy remains limited by poor cell retention and insufficient duration of therapeutic factor release. Here, we describe a simple, scalable and adaptable micromoulding strategy for fabricating biodegradable microwell scaffolds which can encapsulate therapeutic cells and enable paracrine delivery in ischaemic tissue. Using 3D-printed moulds and solvent-cast polymer blends, we generated highly porous microwell scaffolds with tuneable geometry and degradation kinetics that promote mesenchymal stromal cell (MSC) spheroid formation while permitting efficient molecular exchange. Encapsulated MSCs remained viable and metabolically active for several weeks and secreted greater amounts of pro-angiogenic and vascular remodelling-associated factors, including VEGF, IL-6, IL-8, and some chemokines. Co-culture with encapsulated MSCs preserved skeletal and cardiac myocyte viability following hypoxia/reoxygenation injury and promoted endothelial tube formation in vitro. In a mouse model of hind limb ischaemia, implantation of MSC-encapsulated scaffolds improved limb perfusion, reduced distal necrosis, enhanced donor cell retention, and attenuated chronic fibro-adipogenic muscle remodelling compared to direct intramuscular MSC injection or acellular scaffolds. Together, these findings demonstrate that microwell encapsulation scaffolds can enable sustained paracrine signalling and improve regenerative outcomes. This platform offers a simple and flexible approach for biomaterial-guided cell therapies in ischaemic disease.