Stem cells are self-renewing cell types with varying potentials for differentiation. Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are pluripotent and can give rise to nearly any cell type. Others such as hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs), while still multipotent, differentiate into more specific, yet limited lineages. Sources of stem cells for research include umbilical blood and tissue, bone marrow, and amniotic fluid. Ready-to-use kits are available for the rapid and reliable isolation of stem cells and progenitor cells. Such kits typically identify key cellular markers and separate using magnetic particles.