Methods for Increasing Safety of Embryonic Stem Cells


This technology reduces the number of residual stem cells derived from pluripotent stem cells to lessen a population’s tumorigenic potential.

Problem Addressed

Embryonic stem (ES) cells may produce any cell type giving them enormous clinical potential including treatments for heart disease, diabetes, Parkinson’s disease and leukemia. However, ES cells may cause tumors upon implantation. This invention includes methods to reduce the carcinogenic risk of ES cells.


Differentiation of ES cells while exposed to low oxygen for prolonged periods of time reduces the number of residual pluripotent cells and therefore the tumorigenic potential of the cellular population. Lowered expression of genes that regulate pluripotency in cells, including Oct 4, Sox2, and Nanog, is a detectable marker for reduced tumorigenic risk. Increased differentiation time significantly decreases the presence of the detectable markers. Furthermore, low oxygen drastically reduces the tumorigenic potency. For example, at thirty days differentiation the fraction of cells expressing Oct4-GFP at high intensity was one-hundred and forty times lower under 7mmHg compared to populations at 142 mmHg.


  • Reduces the risk of tumor formation upon implantation of ES cells