Human Cord Blood CD133 Cells (also known as Prominin-1 or AC133) has been identified as an important cell surface marker. Cells expressing the CD133 marker are commonly referred to as primitive hematopoietic stem and progenitor cells (HSCs and HPCs). While cells expressing the CD133 marker are usually undifferentiated embryonic stem cell lines, this cell type is usually harvested from bone marrow and cord blood but can be also found in multiple locations including the liver, kidney, prostate, muscle, and neural tissue.