Melt electrowriting scaffolds for investigating Schwann cell-mediated modulation of vascular network formation

Abstract Vascularization remains a major challenge in tissue engineering, restricting both the functional integration of grafts as well as the physiological relevance of in vitro models. Inspired by the crucial role of Schwann cells (SCs) in guiding vascular development, we investigated their influence on the vascular network formation of human microvascular endothelial cells (HMVECs). Using melt electrowriting (MEW), we fabricated scaffolds consisting of a single layer of parallel fibers to mimic the oriented axons of the peripheral nerve. A suspended seeding approach was carried out to ensure rat-derived SCs adhered specifically to the fibers, creating parallel arrays with SCs exhibiting strong attachment, viability, and upregulation of myelination-, neurotrophic-, and pro-angiogenic-related genes. A customized system was built to co-culture SCs-laden scaffolds with HMVECs seeded on a hydrogel (2D) and in a hydrogel (3D). The parallel fiber distances were varied to assess the spacing of the SC arrays that impacted HMVEC organization. The results revealed that SCs on MEW scaffolds exhibited enhanced expression of key genes compared to a 2D monolayer control. Further, these SC-laden scaffolds significantly enhanced HMVEC network formation in both 2D and 3D environments, with reduced fiber distance showing stronger pro-angiogenic responses. To evaluate species differences, human dental pulp stem cell-derived SCs (HDPSC-SCs) were compared with rat primary SCs. HDPSC-SCs not only showed enhanced expression of pro-angiogenic genes on the scaffold but also promoted superior network formation compared to rat SCs. Collectively, our findings highlight the ability of MEW scaffolds to both pattern SC growth and stimulate a pro-regenerative SC phenotype as a strategy to modulate vascular network formation. This provides a foundation for using the patterning of SCs to drive neurovascular organization for in vitro models and more broadly as an approach of regenerative medicine.