Modeling and fabrication of MEW-3D tubular scaffolds with tendon mechanical behavior for tenocyte differentiation

Tendon injuries present substantial challenges in clinical settings, where traditional treatments often lead to suboptimal outcomes, including scar tissue formation, reduced strength, limited range of motion, and re-ruptures. These difficulties primarily arise from the complex hierarchical structure of tendons and their limited healing capacity. Tissue engineering offers promising solutions for tendon regeneration and muscle-to-bone reconnection, typically through the use of biodegradable scaffolds that mimic the extracellular matrix of tendons, thereby supporting cell growth and tissue formation. However, several obstacles must be addressed to develop tendon reconstruction strategies suitable for clinical application. In this study, we developed computational models to design and produce Melt Electrowriting (MEW)-3D tubular structures that replicate the mechanical properties of native mouse Achilles tendons, improving the guidance of tenocyte growth and differentiation. These models incorporated a new approach to consider the non-continuum nature of printed scaffolds formed by sets of fibers interacting with one another. Moreover, these structures facilitated cell confinement, expansion, and alignment, resulting in bundle-like formations with enhanced tensile properties. Importantly, tenocyte differentiation was achieved through a two-step cell culture protocol, which involved transitioning cells from high to low serum media. This approach effectively mitigated the phenotypic drift that often occurs with long-term cell cultures. Statement of Significance Tendon injuries are a common issue in healthcare, often leading to scar tissue, weaker tendons, limited mobility, and frequent re-injury. Tendon engineering aims to address these challenges by using biodegradable "scaffolds" that mimic the natural tendon environment, supporting cell growth and tissue repair. In this study, we developed computational models to design 3D tubular structures using a printing method called Melt Electrowriting (MEW). These structures replicate the mechanical properties of mouse Achilles tendons, guiding tendon cells to grow and differentiate effectively. By creating scaffolds from interwoven fibers, we closely replicated how natural tendon fibers interact, allowing cells to form strong, organized bundles. This approach may improve engineered tendon strength and durability, addressing key challenges in tendon reconstruction strategies.