Methods of screening embryonic progenitor cell lines

Aspects of the present invention include methods and compositions related to the production and use of numerous clonal lineages of embryonic progenitor cell lines derived from differentiating cultures of primordial stem cells with diverse molecular markers and having been cultured for >21 doublings of clonal expansion. The robustness of these clonally-purified lines, their ability to expand for >40 passages while maintaining their pattern of gene expression, lack of tumorigenicity, and their embryonic pattern of gene expression offers novel compositions and methods for modeling numerous differentiation pathways for the first time in vitro, and for the manufacture of purified product not existing in such a purified state in nature or using other manufacturing modalities. Representative progenitor cell lines described herein are capable of development into cutaneous adipocytes, blood-brain barrier cells, neuronal cells, or smooth muscle cells each with therapeutic potential.