The theory is that because these stem cells are fetal cells, they are designed to proliferate and give rise to new tissue, which means they have the potential to produce tumors.

• 由于那些干细胞来自胎儿，它们本来就是要通过自身繁殖来形成新的人体组织，因此理论上它们具有产生肿瘤的潜在可能。