Scientists grow human liver tissue to be used for transplantation

As of January 2011, more than 16,000 Americans are on the waiting list to receive a suitable liver according to data from the Organ Procurement and Transplantation Network. Liver cell (hepatocyte) transplantation offers a possible solution in overcoming the organ shortage. In addition, liver cells have excellent regenerative potential making liver cell transplantation a viable therapeutic approach for patients with metabolic defects or fulminant hepatic failure as the native liver is preserved while liver dysfunction may resolve as regeneration occurs.

Dr. Joerg-Matthias Pollok, Head of the Laboratory for Tissue Engineering and Cell Transplantation, Department of Hepatobiliary and Transplantation Surgery at the University Medical Center in Hamburg, Germany explains, "Currently isolated liver cells are used for liver cell transplantation, but these cells suffer during cell isolation and cryopreservation, which is one reason there is limited success with this type of transplant procedure." In applying their tissue engineering approach, the German researchers were able to successfully create new liver tissue providing a potential solution to the obstacles challenging liver cell transplantation.

The team isolated liver cells from 12 human liver specimens with a viability of 82%. After a two-day culture period, liver cells formed tightly packed cellular aggregates, called spheroids, and took on a liver-like appearance. Human liver cells were distributed across a three-dimensional porous structure of the polymer scaffolding. From day two to four, the average number of spheroids more than doubled from 18 to 41 per visual field. "Our experimental model represents a promising technique to culture human liver cells and prepare them for transplantation on a biodegradable polymer scaffold into the peritoneal cavity," concluded Dr. Pollok. "Further studies are underway to confirm our results and may ultimately offer viable clinical options for liver cell transplantation in the future."

A related editorial also published in Liver Transplantation this month acknowledges the huge clinical potential for liver cell transplantation. Humphrey Hodgson, M.D., from the UCL Medical School in London wrote that a number of liver cell transplantation approaches have been used in uncontrolled trials, but effective clinical protocols have not yet been established. He noted that while no technique has emerged as a proven clinical approach, the use of human rather than rodent cells as demonstrated by Pollok et al. is an important step in advancing the science behind liver cell transplantation.