Stem cell biology, hormone/matrix synergies and liver differentiation.

Extracellular matrix, in conjunction with hormones and growth factors, plays a profound role in regulating gene expression in liver and in all tissues. The availability of matrix components for liver cells in culture is having a major impact on our ability to study every aspect of gene expression. Its significance has been particularly profound in permitting cultures with partial restoration of transcription rates of tissue-specific mRNAs. However, the matrix reagents available to date are not so potent as the forms known to be present uniquely in the liver. Thus, there is a great need to purify and characterize these tissue-specific matrix components (e.g. heparin-PG) to enable the eventual production of them for general use by investigators. The use of matrix reagents and the eventual use of cultures of liver stem cells will begin a new era in the understanding of liver differentiation.