Methods and compositions for inducing hematopoietic cell differentiation

A method of identifying definitive hemogenic endothelium (HE) cells in pluripotent stem cell differentiation, comprising:

• (i) obtaining a cell population undergoing differentiation;
• (ii) introducing to the cell population an antibody specific to CD93;
• and
• (iii) identifying a subpopulation of cells in the cell population having CD93 expression level less than 1%, wherein the subpopulation of cells comprise definitive hemogenic endothelium cells.

A method of generating pluripotent stem cell derived definitive hemogenic endothelium (HE) cells, comprising culturing pluripotent stem cell derived mesodermal cells having definitive hemogenic endothelium (HE) potential in a medium comprising a Wnt pathway agonist to obtain definitive HE cells, wherein the obtained definitive HE cells:

• (i) are increased in numbers and percentage in cell population;
• (ii) have increased potency in differentiation;
• and/or
• (iii) improved HE cellularity,
• as compared to culturing without the Wnt pathway activator.

A method of generating antigen-specific induced pluripotent stem cells (iPSC) or derivative hematopoietic lineage cells therefrom comprising:

• a) isolating antigen specific T cells from a selected source that is donor-, disease- or treatment response-specific;
• b) reprogramming the antigen-specific T cells to obtain pluripotent stem cells;
• and
• c) directing differentiation of the pluripotent stem cells of step b) to hematopoietic lineage cells, wherein directing differentiation comprises:
• (i) contacting the pluripotent stem cells with a composition comprising a BMP pathway activator, and optionally bFGF, to obtain mesodermal cells;
• and
• (ii) contacting the mesodermal cells with a composition comprising a BMP pathway activator, bFGF, and a WNT pathway activator, to obtain mesodermal cells having definitive hemogenic endothelium (HE) potential;
• wherein mesodermal cells and mesodermal cells having definitive HE potential are obtained in steps (i) and (ii) without the step of forming embryoid bodies.