A method of distinguishing mesenchymal stem cells (MSCs) in a primary culture of cells derived from a placenta-related tissue is provided. Also provided is a method of increasing the purity of MSC population in a primary culture of cells derived from a placenta-related tissue. Further provided is a method of isolating a MSC population which is more responsive in an inflammatory environment. Said methods each comprise a step of sorting the cells by a marker of EphA2.
