Provided herein are human embryonic stem cells and their method of culturing. In one embodiment, the human embryonic stem cells are maintained in an environment containing an extracellular matrix isolated from feeder cells and a conditioned medium pre-conditioned by the feeder cells; the feeder cells are pre-inactivated by either gamma ray radiation or by mitomycin C treatment. The cultured human embryonic stem cells remain substantially undifferentiated and maintain their pluripotency to differentiate into three germ layer cells.