[Neovascularisation and free microsurgical transfer of cartilage-engineered constructs]

Clinical imperatives for new cartilage to replace or restore the function of traumatized or missing tissue as a consequence of trauma, inherent malformations or disease has led to the need for therapies or procedures to generate cartilage for clinical applications. To ensure shape, function, and survival, in vitro cartilage-engineered constructs need to be revascularized. This study presents a viable method for neovascularization and free microsurgical transfer of these in vitro constructs.

Twelve female Chinchilla Bastard rabbits were operated. Cartilage-engineered constructs were created by isolating chondrocytes from auricular biopsies, amplifying in monolayer culture, and then seeding them onto polycaprolactone scaffolds. In each prefabricated skin flap, three in vitro cartilage-engineered constructs measuring 2×2×0.5 cm and one construct without cells, which served as the control, were implanted beneath an 8×15-cm random-pattern skin flap, neovascularized by implantation of an arteriovenous vascular pedicle with maximal blood flow. After 6 weeks, the neovascularized flaps with embedded cartilage-engineered constructs were completely removed based on the newly implanted vascular pedicle, and then freely retransferred into position using microsurgery. Macroscopic observation, histology, selective microangiography, and immunohistochemistry were performed to determine the construct vitality, neovascularization, and new cartilage formation.

All neovascularized skin flaps with embedded tissue-engineered cartilage constructs were effectively free-transferred as free flaps. The implanted constructs were protected and well integrated within the flap. All constructs were well neovascularized and showed histologically stability in both form and size. Immunohistology showed the existence of cartilage-like tissue with extracellular matrix neosynthesis.

Our experimental study revealed the reliable ability of neovascularization and free microsurgical transplantation of cartilage-engineered constructs using prefabricated flaps. With respect to effective clinical application, engineered cartilage composed of a patient's own cells can become a feasible option for the reconstruction of large cartilage defects or auricular reconstruction using this method. The procedure also represents a promising alternative for clinical practice due to minimal donor site morbidity and favorable aesthetic outcomes.