Scaffold-free biofabrication of liver

The liver performs multiple functions that are essential for life. The development of a functional human liver tissue model showing a similar response to that in the human body for investigations of liver disease and medical treatment has been challenging. Many studies have described in vitro human liver tissue models based on two-dimensional cultures of primary hepatocytes. However, those models lost their function rapidly. Efforts to engineer a three-dimensional liver tissue model are currently underway. Regenerative therapy using engineered liver tissue has been proposed as a promising alternative to orthotopic liver transplantation for patients presenting with liver failure and liver-based inherited metabolic diseases. To increase its potential clinical utility, the next step will be to make the human liver model large enough to reflect the liver function in the human body. The key to constructing larger tissue specimens is to avoid creating an ischemic environment ex vivo. In this respect, the "Kenzan" method has advantages through its elaborate geometry and immediate execution of culture circulation. We successfully fabricated human liver-like tissue exhibiting self-tissue organization and engraftment on the liver of a rat using the "Kenzan" method. Our efforts may provide new insight into cell-based therapy and facilitate the shift from cell- to bio-tissue-based therapy.