Impact of liver surgery on liver transplantation:

[Adipose tissue-derived stem cells: hepatic plasticity]

Currently, the only effective treatment for end-stage liver disease is liver transplantation. The number of patients on the waiting list increases considerably each year, giving rise to a wide imbalance between supply and demand for healthy livers. Knowledge of stem cells and their possible use have awakened great interest in the field of hepatology, these cells being one of the most promising short-term alternatives. Hepatic stem cell therapy consists of the implantation of healthy cells capable of performing the functions that damaged cells are unable to carry out. Recent observations indicate that several stem cells can differentiate into distinct cell lineages. Hepatic differentiation of adult stem cells from several origins has yielded highly promising results. Adipose tissue in adults contains a reservoir of stem cells that can be induced and differentiated into different types of cells, showing a high degree of plasticity. Because of its abundance and easy access, adipose tissue is a promising source of adult stem cells for hepatic stem cell therapy. The present article reviews the progress made in the differentiation of adult stem cells from adipose tissue into cells with hepatic phenotype. We also discuss the potential application of this technique as a therapy for temporary metabolic support in patients with end-stage liver failure awaiting whole organ transplantation, as a method to support liver function and facilitate regeneration of the native liver in cases of fulminant hepatic failure, and as a treatment in patients with genetic metabolic defects in vital liver functions.

Morphological and functional analysis of rat hepatocyte spheroids generated on poly(L-lactic acid) polymer in a pulsatile flow bioreactor

Liver neo-tissue suitable for transplantation has not been established. Primary rat hepatocytes were cultured on three-dimensional biodegradable polymer matrices in a pulsatile flow bioreactor with the intention of inducing tissue formation and improving cell survival. Functional and structural analysis of the hepatocytes forming liver neo-tissue was performed. Biodegradable poly(L-lactic acid) (PLLA) polymer discs were seeded with 4 x 10(6) primary rat hepatocytes each, were exposed to a pulsatile medium flow of 24 mL/min for 1, 2, 4, or 6 days and were investigated for monoethylglycinexylidine (MEGX) formation, ammonia detoxification, Cytokeratin 18 (CK18) expression, and preserved glycogen storage. Fine structural details were obtained using scanning and transmission electron microscopy. Spheroids of viable hepatocytes were formed. MEGX-specific production was maintained and ammonia removal capacity remained high during the entire flow-culture period of 6 days. CK18 distribution was normal. Periodic-acid- Schiff reaction demonstrated homogenous glycogen storage. The hepatocytes reassembled to form intercellular junctions and bile canaliculi. Functional and morphological analysis of rat hepatocytes forming spheroids in a pulsatile flow bioreactor indicated preserved and intact hepatocyte morphology and specific function. Pulsatile flow culture on PLLA scaffolds is a promising new method of hepatic tissue engineering leading to liver neo-tissue formation.