The bioengineering of perfusable endocrine tissue with anastomosable blood vessels.

Organ transplantation is a definitive treatment for endocrine disorders, but donor shortages limit the use of this technique. The development of regenerative therapies would revolutionize the treatment of endocrine disorders. As is the case for harvested organs, the ideal bioengineered graft would comprise vascularized endocrine tissue, contain blood vessels that could be anastomosed to host vessels, have stable blood flow, and be suitable for transplantation into various sites. Here, we describe a transplantable endocrine tissue graft that was fabricated by ex vivo perfusion of tricultured cell sheets (islet β-cells, vascular endothelial cells, and mesenchymal stem cells) on a vascularized tissue flap of in vivo origin. The present study has three key findings. First, mild hypothermic conditions enhanced the success of ex vivo perfusion culture. Specifically, graft construction failed at 37°C but succeeded at 32°C (mild hypothermia), and endocrine tissue fabricated under mild hypothermia contained aggregations of islet β-cells surrounded by dense vascular networks. Second, the construction of transplantable endocrine tissue by ex vivo perfusion culture was better achieved using a vascular flap than a muscle flap. Third, the endocrine tissue construct generated using a vascular flap could be transplanted into the rat by anastomosis of the graft artery and vein to host blood vessels, and the graft secreted insulin into the host's circulatory system for at least 2 weeks after transplantation. Endocrine tissues bioengineered using these techniques potentially could be used as novel endocrine therapies.