The invention described herein relates to methods of isolating non-embryonic stem cell, e.g., adult stem cell, from a non-embryonic tissue, e.g., an adult tissue or organ. Non-embryonic stem cells (e.g., adult stem cells) thus isolated from the various tissues or organs can self-renew or propagate indefinitely in vitro, are multipotent and can differentiate into the various differentiated cell types normally found within the tissue or organ from which the stem cells are isolated. In addition, the isolated stem cells can be propagated through clonal expansion of a single isolated stem cell, to produce a clone of which at least about 40%, 70%, or 90% or more cells within the clone can be further passaged as single cell originated clones.
