A replicating in vitro cell culture of human placental mesenchymal stem cells comprising； cells which maintain a potential to differentiate to derivatives of multiple progenitor cell types throughout the culture. The progenitor cell types may include neuronal cells, oligodendrocytes and beta-cells. A method of treating a disease, disorder, or condition in a human comprising administering a pharmacologically effective dose of human placental mesenchymal stem cells to the human. A method for producing human placental mesenchymal stem cells.
