С stromal жасушалары: қасиеттері мен қызметтері

Connective tissue cell of any organ
Stromal cells, or mesenchymal stromal cells, are differentiating cells found in abundance within bone marrow but can also be seen all around the body. Stromal cells can become connective tissue cells of any organ, for example in the uterine mucosa (endometrium), prostate, bone marrow, lymph node and the ovary. They are cells that support the function of the parenchymal cells of that organ. The most common stromal cells include fibroblasts and pericytes. The term stromal comes from Latin stromat , "bed covering", and Ancient Greek στρῶμα, , "bed". Stromal cells are an important part of the body's immune response and modulate inflammation through multiple pathways. They also aid in differentiation of hematopoietic cells and forming necessary blood elements. The interaction between stromal cells and tumor cells is known to play a major role in cancer growth and progression. In addition, by regulating local cytokine networks (e. g. M CSF, LIF), bone marrow stromal cells have been described to be involved in human hematopoiesis and inflammatory processes. Stromal cells (in the dermis layer) adjacent to the epidermis (the top layer of the skin) release growth factors that promote cell division. This keeps the epidermis regenerating from the bottom while the top layer of cells on the epidermis are constantly being "sloughed" off the body. Additionally, stromal cells play a role in inflammation responses, and controlling the amount of cells accumulating at an inflamed region of tissue.

Defining a stromal cell is of importance because it was a source of difficulty in the past. Without a strong definition studies could not cross over or gain knowledge from each other because a stromal cell was not well defined and went by a plethora of names. A stromal cell is currently more specifically referred to as a mesenchymal stromal cell (MSC). It is non hematopoietic, multipotent, and self replicating. These factors make it an effective tool in potential cell therapies and tissue repair. Being a mesenchymal cell indicates an ability to develop into various other cell types and tissues such as connective tissue, blood vessels, and lymphatic tissue. Low levels of human leukocyte antigen (HLA DR) make MSCs hypoimmunogenic. MSCs have trilineage differentiation capacity where they are able to adapt into osteoblast, chondrocytes, and adipocytes. While a majority is found in the bone marrow scientists now know that stromal cells can be found in a variety of different tissues as well. These can include adipose tissue, endometrium, synovial fluid, dental tissue, amniotic membrane and fluid, as well as the placenta. High quality stromal cells are located in the placenta, due to their young age. Furthermore, the tumor stroma is primarily composed of the basement membrane, fibroblasts, extracellular matrix, immune cells, and blood vessels. Typically, most host cells in the stroma are characterized by tumor suppressive abilities. However, during malignancy, the stroma will undergo alterations to consequently incite growth, invasion, and metastasis. These changes include the formation of carcinoma associated fibroblasts (CAFs) which comprises a major portion of the reactive tissue stroma and plays a critical role in regulating tumor progression. Certain types of skin cancers (basal cell carcinomas) cannot spread throughout the body because the cancer cells require nearby stromal cells to continue their division. The loss of these stromal growth factors when the cancer moves throughout the body prevents the cancer from invading other organs. Stroma is made up of the non malignant cells, but can provide an extracellular matrix on which tumor cells can grow. Stromal cells may also limit T cell proliferation via nitric oxide production, hindering immune capability.

MSCs have the potential to be used in multiple disease interventions. One important feature of MSCs is that they can go virtually undetected by the immune system. The stromal cells possess serine proteases which are an inhibitor of the immune response. They also do not carry receptors that relate to the immune system or are not in high enough concentrations to admit a response. This is helpful for the future of MSC cell therapies because there will be little to no negative effects from a possible immune response. There is promising research in the fields of autoimmune disorders such as multiple sclerosis and rheumatoid arthritis as well as wound healing, COPD, and even acute respiratory distress syndrome (an effect of COVID 19). Stromal cells have the unique ability to create an immune modulated environment in order to best respond to foreign and known particles. The reason for halted use of MSCs is the lack of knowledge of the cells in vivo. Most research of these cells have been done in controlled laboratory environments which can sometimes alter the effects seen. The potentials, however, for cell therapy in tissue repair, immune modulation, and anti tumor agent distribution are promising.