Abstract: Objective To construct an engineered scaffold-free tendon tissue using bone-marrow mesenchymal stem cells (BMSCs)pre-treated with connective tissue growth factor (CTGF) and ascorbic acid. Methods After isolated from rat bone marrow and cultured, BMSCs at P3 were treated by CTGF and ascorbic acid for 2 weeks, and a cellular sheet formed.The BMSCs cell sheets were collected, then rolled up and loaded on a 1 cm wide U-shaped spring to form tendon-like structure.The engineered tendon tissue was sutured to posterior midline of nude mice，and histological and immunohistochemical staining were performed to assess the characteristics. Results The engineered tendon tissue showed an immature tissue structure with relatively loose extra-cellular matrix.After transplanting the engineered tissue into nude mice for 12 weeks, neo-tendon tissues formed with good collagen fibril alignment and spindle shaped cells. Conclusion An engineered tendon using BMSCs and CTGF without exogenous scaffolds was constructed in this study, and it showed potentials for neo-tendon formation.This could be a potentially new approach for tendon repair and regeneration.