Allogeneic mesenchymal stem cells (MSCs) are a type of adult stem cell derived from a donor that can be used to treat various diseases and conditions. One of the unique properties of allogeneic MSCs is that they do not express human leukocyte antigens (HLA), which are proteins found on the surface of cells that help the immune system distinguish between self and non-self-cells. This lack of HLA expression makes allogeneic MSCs an attractive option for use in cell-based therapies as they are less likely to be rejected by the patient's immune system.

The reason why allogeneic MSCs do not express HLA antigens is due to the fact that they are derived from the mesoderm, which is the embryonic layer that gives rise to connective tissue and muscle. The cells that make up the mesoderm, including MSCs, do not express HLA antigens because they do not need to interact with the immune system. Unlike cells such as blood cells, which are constantly exposed to potential pathogens and need to be able to signal the immune system to attack invaders, MSCs are not in contact with the immune system and do not need to express HLA antigens.

Another reason why allogeneic MSCs do not express HLA antigens is that they have a low level of genetic expression. MSCs are considered to be "immortal" cells, meaning that they can divide indefinitely without losing their ability to differentiate into various cell types. This immortality is due to the fact that MSCs have a low level of genetic expression, which means that they do not activate the genes that are responsible for HLA expression.

In addition, allogeneic MSCs also have immune-modulatory properties, meaning that they can suppress the immune response. They can release a variety of cytokines, which are small signaling molecules that can influence the behavior of other cells. These cytokines can influence the activity of immune cells such as T-cells and macrophages, which can help to dampen the immune response and prevent the rejection of the transplanted cells.

It is important to note that allogeneic MSCs are not completely immunologically invisible, and the risk of immune rejection still exists. However, the low expression of HLA antigens combined with the immune-modulatory properties of MSCs can decrease the risk of immune rejection dramatically and increase the chances of successful treatment.

In conclusion, the lack of HLA expression in allogeneic MSCs is a crucial factor that makes them an attractive option for use in cell-based therapies. Their ability to differentiate into various cell types, combined with their lack of HLA expression and immune-modulatory properties, make them a promising option for treating a wide range of diseases and conditions. 

Please reach out to your Patient Advisor for more information.