"There are many different causes of the scarring. Viruses are common. Hepatitis B, hepatitis C, what we call autoimmune diseases where the body attacks the liver itself such as primary biliary cirrhosis is an autoimmune disease; sclerosing cholangitis is an autoimmune disease; and so those diseases where the liver is being destroyed by either the virus or an autoimmune disease, it can only scar, and why it doesn't regenerate has to do with the fact that there is this ongoing scar tissue that blocks that regeneration."