stammirakkude

Stammirakkude, the Estonian term for stem cells, are undifferentiated cells characterized by their ability to renew themselves and to differentiate into specialized cell types. They occur in developing embryos and in many adult tissues, where they participate in growth, maintenance, and repair.

Potency is a central concept. Totipotent cells can form all embryonic and extraembryonic tissues, seen only in the zygote and early divisions. Pluripotent cells, such as embryonic stem cells and induced pluripotent stem cells, can generate cell types from all three germ layers but cannot form placental tissues. Multipotent cells are more restricted, giving rise to multiple, related cell types within a tissue or organ (for example, hematopoietic stem cells produce blood lineages). Oligopotent and unipotent cells are even more limited, differentiating into a few or a single cell type, respectively.

Main sources include embryonic stem cells derived from the inner cell mass of blastocysts; adult stem cells found in tissues such as bone marrow, skin, and the brain; and induced pluripotent stem cells created by reprogramming differentiated cells back to a pluripotent state. Culturing stem cells relies on specific growth factors and conditions to maintain their properties and guide differentiation toward desired lineages.

Applications of Stammirakkude research span regenerative medicine, tissue engineering, disease modeling, and drug discovery. Clinical use includes bone marrow transplantation and experimental therapies aimed at repairing damaged tissues. Ethical and safety considerations include debates over embryo use, the development of alternative methods like iPSCs, and risks such as immune rejection and potential tumor formation, necessitating rigorous oversight and quality control.