An open-source mechanical stretching platform for controlled stimulation of tenocytes on melt electrowritten scaffolds

Tendons, composed of fibrous connective tissue, are crucial in body movement but difficult to heal after a rupture. Effective treatment for tendon injuries necessitates innovative scaffold designs and external (biomechanical) cues to promote tissue development. This study explores the use of additive manufacturing techniques, specifically Melt Electrowriting (MEW), to produce customized scaffolds with controlled microarchitectures resembling native tendons. The melt electrowritten (MEW) scaffolds were designed to mimic the hierarchical architecture and mechanical properties of native tendons, such as a toe region, allowing for a proper response to stretching. Furthermore, a cost-effective mechanical stretching platform (called MESP) was designed and fabricated using 3D printing technology to enable the application of controlled mechanical cues, relevant to tendon healing, directly to the printed scaffolds. The fabricated device demonstrated high precision at low to moderate speeds (1–10 RPM), maintaining consistent positional accuracy. Cyclic uniaxial stretching for 10 days with a 10 % strain, 0.17 Hz frequency and 36,000 cycles resulted in significantly enhanced tenocytes viability and metabolic activity compared to static controls. The stimulated scaffolds exhibited enhanced actin and collagen type I expression, as proved by immunofluorescence staining. Additionally, the alignment of cell actin fibers was directed along the stretching axis, accompanied by organized collagen deposition, which underscores stimulation’s critical role in supporting tenocyte activity and promoting tendon-like tissue organization. In conclusion, the developed MESP offers high accuracy and flexibility at low production and maintenance costs. In combination with precisely engineered MEW scaffolds, it offers a unique and effective approach for promoting tissue regeneration through mechanical stimulation.