Embryonic Cell-Based Therapeutic Candidate Screening Systems, Models for Huntington's Disease and Uses Thereof

A method for identifying therapeutic candidates for treatment of Huntington's Disease (HD) comprising:

• contacting a test substance with each of
• a first clonal population of human embryonic stem cells comprising a wild type Huntingtin (HTT) gene, and
• a second clonal population of human embryonic stem cells isogenic to the first population, wherein the cells in the second population are genetically modified to comprise a nucleotide segment, wherein the nucleotide segment, upon expression, results in a polyQ repeat peptide segment comprising at least 36 or at least 40 glutamine residues in the N-terminal region of the HTT protein;
• and
• determining whether the test substance wholly or partially reverses the phenotype of the cells of the second clonal population.

A fate reporter cell for use in monitoring induction of germ layers, or fate acquisition, or both, in human embryonic stem cells, wherein the fate reporter cell comprises at least one of the following:

• a first detectable marker inserted into the genome of the cell so as to co-express with a first germ layer specific marker;
• a second detectable marker inserted into the genome of the cell so as to co-express with a second germ layer specific marker;
• and
• a third detectable marker inserted into the genome of the cell so as to co-express with a third germ layer specific marker.

A method for identifying a therapeutic candidate for Huntington's disease comprising:

• (a) contacting a clonal population of human embryonic stem cells or human neural progenitor cells or human neurons differentiated therefrom, wherein the clonal population expresses a mutant Huntingtin (HTT) gene which encodes an HTT protein comprising a polyQ repeat peptide segment of least 40 glutamine residues with a test compound;
• (b) culturing said clonal population;
• and
• (c) detecting whether the phenotype of the clonal population partially or fully reverts to the wild-type phenotype, wherein a test compound that causes a partial or complete reversion to the wild-type phenotype is a therapeutic candidate for Huntington's disease.

A method of screening for a therapeutic candidate for Huntington's Disease, comprising:

• (a) culturing
• a first clonal population comprising human embryonic stem cells or human neuronal cell progenitors or human neurons differentiated therefrom, said cells in the first clonal population comprising a wild-type Huntingtin gene (HTT);
• and
• a second clonal population of human embryonic stem cells, human neuronal cell progenitors or human neurons, said cells in the second clonal population isogenic to the first population but comprising an HTT genetically modified to comprise a nucleotide segment, wherein the nucleotide segment, upon expression, results in a polyQ repeat peptide segment comprising at least 40 glutamine residues in the N-terminal region of the HTT protein;
• in the presence of a therapeutic candidate;
• (b) measuring a parameter that is altered in the second clonal population as compared to the first clonal population;
• and
• (c) determining whether the therapeutic candidate reverts the parameter to the wild type phenotype of the first clonal cell population.