Myocardial grafts and cellular compositions

Patent Number: RE37,978

This patent is useful for anyone who is performing embryonic stem cell differentiation applications and desires a method of purifying unique differentiated cells from the embryonic stem cell. Since embryonic stem cells spontaneously differentiate into various lineages depending on culture conditions, this patent provides means of "fishing out" cells based on activation of cell-specific markers. Competing technology would include methods of purifying out cells based on surface markers using antibodies. Based on the claims section, this patent has three independent claims. The first one claims a method of purifying cells of a certain phenotype by transfecting embryonic stem cells with a molecular marker that is expressed when the cells differentiate into a desired type. One potential application would be to transfect embryonic stem cells with a an albumin promoter driving expression of GFP. When GFP positive cells are detected, the patent covers their selection and purification. The second independent claim covers a cell expressing the marker being a DNA molecule. The third independent claim covers a method of purifying cells from a mixed population, based on expression of the cell phenotype-specific marker. However, reading the specification, one sees the invention is directed primarily towards methods of deliverying and using cardiac progenitor cells. The 4th example, however is directed towards the claimed invention in that it demonstrates purification of a substantially homogeneous cardiomyocyte population from embryonic stem cells that have been transfected with pGK-HYG (hygromycin) plasmid and a plasmid containing a MHC-neo.sup.r gene. The pGK-HYG plasmid provided selection for transfected embryonic stem cells, while the mMHC-neo. gene facilitated a second round of selection on differentiated cardiomyocyte cells: incubation in the presence of G418 antibiotic was shown to eliminate non-cardiomyocytes (that is, cells in which the MHC promoter is not active). One publication that seems to describe the invention is (Zandstra PW et al. Tissue Eng. 2003 Aug;9(4):767-78)

View this patent on the USPTO website.