Methods for inducing differentiation of pluripotent cells

Patent Number: 7,332,336

Mesenchymal stem cells are originally thought of as bone marrow derived, adherent cells, that have the ability to differentiate into a variety of tissues. Initial studies demonstrated that mesenchymal stem cells can differentiate into bone, cartilage, fat and muscle. These cells possess a very strong possibility for commercialization and therapeutics development since they can be administered to patients intravenously for various conditions. More shockingly, mesenchymal stem cells apparently do not need to be HLA-matched with the recipient in order to elicit therapeutic effects. Of course there is no guarantee that once mesenchymal stem cells actually differentiate into a new tissue that the new tissue will not be rejected. It is possible that mesenchymal stem cells induce therapeutic effects through their ability to produce various cytokines and growth factors, and not through differentiation into new tissue.

Mesenchymal stem cells have previously been administered into animal models of liver failure with positive effects. One of the mechanisms by which this therapeutic effect is mediated was postulated to involve inhibition of stellate cell activation and protection of hepatocytes from apoptosis. Others have described bone marrow stem cells transdifferentiating into hepatic oval cells. In the current patent the differentiation of mesenchymal stem cells in hepatocytes is covered.

The first independent claim of the patent covers “a method for differentiating mesenchymal stem cells to hepatocytes”. The method as described involves a) exposing the cultured mesenchymal stem cells in a tissue culture medium which is supplemented with the combination of FGF-1, FGF-4, and hepatocyte growth factor, and b) culturing the cells with another medium that contains oncostatin M. Dependent claims include culturing the cells on a gelatin-coated dish when they are exposed to the FGF-1, 4 and HGF mixture, and then transferring the cells into a culture that is coated with Type I collagen. Another dependent claim covers the overall culture in a gelatin coated culture dish.

The second independent claim covers the generation of hepatocytes from embryonic stem cells. In this claim the process of generating hepatocytes includes the steps of a) exposing the embryonic stem cells to HGF, LIF, and retinoic acid; b) culturing the cells in FGF-1, FGF-4, and HGF, and c) culturing the cells in oncostatin M.

View this patent on the USPTO website.