Conditioned media for propagating human pluripotent stem cells

A method for preparing a conditioned medium for proliferating primate pluripotent stem (pPS) cells, comprising:

• a) culturing cells in a tissue culture medium, thereby conditioning the medium;
• and then
• b) harvesting the conditioned medium from the culture;
• wherein the cells used to condition the medium are from a human cell line immortalized with telomerase reverse transcriptase (TERT);
• and
• wherein pPS cells proliferate without differentiation when cultured in an environment essentially free of feeder cells but comprising the conditioned medium, an extracellular matrix, and a growth factor.

A composition of undifferentiated pluripotent stem cells obtained from a human blastocyst, proliferating in a growth environment containing an extracellular matrix and a medium conditioned by:

• a) culturing cells in a tissue culture medium, thereby conditioning the medium;
• and then
• b) harvesting the conditioned medium from the culture;
• wherein the cells used to condition the medium are from a non-malignant mouse cell line immortalized by genetic engineering, or a human cell line that proliferates in culture for at least 60 days.

A method for preparing a conditioned medium for proliferating human blastocyst-derived pluripotent stem cells, comprising:

• a) culturing cells of a telomerized mammalian cell line in a tissue culture medium, thereby conditioning the medium;
• b) harvesting the conditioned medium from the culture;
• and then
• c) adding a growth factor to the medium;
• wherein pPS cells proliferate without differentiation when cultured in an environment essentially free of feeder cells, but comprising an extracellular matrix and the conditioned medium.

A conditioned medium for proliferating human blastocyst-derived pluripotent stem cells, produced by a method comprising:

• a) culturing cells of a telomerized mammalian cell line in a tissue culture medium, thereby conditioning the medium;
• b) harvesting the conditioned medium from the culture;
• and then
• c) adding a growth factor to the medium;
• wherein pPS cells proliferate without differentiation when cultured in an environment essentially free of feeder cells, but comprising an extracellular matrix and the conditioned medium.