Adult stem cells

Adult stem cells, also known as tissue stem cells, are immature cells present in the body's fully formed tissues and organs. They have the capacity to renew themselves and differentiate into different types of specialised cells. They are present in various tissues such as bone marrow, heart, kidney, brain and muscle, and can be maintained in culture, in the form of undifferentiated colonies, indefinitely under certain conditions. They are characterised by two essential properties: 

• Multipotency or Unipotency : Adult stem cells have a limited capacity for differentiation. They are generally multipotent, which means that they can differentiate using several markers into a number of specific cell types present in the same tissue, such as SSEA-3, SSEA-4, TRA-1-60, TRA-1-81.
• Auto-renewal : Adult stem cells have the ability to self-renew, i.e. to divide to produce both an identical stem cell and a daughter cell that will undergo subsequent differentiation.
• Role in tissue regeneration : Adult stem cells play a crucial role in the regeneration and repair of damaged tissue. They are mobilised in response to injury or tissue damage to help heal and restore normal tissue function.
• Specific location : Each type of tissue has its own specific stem cells. For example haematopoietic stem cells are found mainly in bone marrow, while the​​​​​​​ mesenchymal stem cells can be found in various connective tissues such as adipose tissue and bone.
• Potential application in regenerative medicine : Adult stem cells have attracted considerable interest in regenerative medicine, as they offer the possibility of treating certain diseases and injuries by regenerating damaged tissue. Areas such as cell therapy and stem cell transplantation are part of this research.
• Age and availability: The capacity for regeneration and the quantity of adult stem cells available diminish with age. This may have implications for the ability of older individuals to recover and regenerate tissue.

The determinants of the pluripotency of these cells are beginning to be better defined, such as the OCT4 transcription factors and NANOG, or the FGFb growth factors and IGF2. The markers that characterise these cells are capable of differentiating into different in vitro cell types.

In general, adult stem cell biomarkers vary depending on the type of stem cell and where it comes from in the body: