Mesenchymal stem cells (MSCs) are multipotent stem cells that can differentiate into bone, muscle, tendon, cartilage and fat cells. They are mainly found in the bone marrow and their main function is the production and repair of skeletal tissue. MSCs have great potential in regenerative medicine and could one day be used to treat bone and cartilage injuries, ischemic heart disease, and inflammatory diseases.
What is a mesenchymal stem cell?
Mesenchymal stem cells (MSCs) are adult stem cells found in bone marrow, adipose tissue, and the umbilical cord. They are multipotent and can differentiate into a variety of different cell types, including bone, muscle, tendon, cartilage, and fat cells.
Location of mesenchymal stem cells
Mesenchymal stem cells are traditionally located in the bone marrow. But they also occur in adipose tissue, blood and umbilical cord.
Function of mesenchymal stem cells
Mesenchymal stem cells lead to a variety of cell types, including muscle, bone, tendon, cartilage, and fat cells. Hence, they play a central role in the growth and repair of skeletal tissues.
In the event of tissue damage, MSCs migrate through the walls of the blood vessels to reach the site of the injury. There they can differentiate into specialized cells that are used to repair and regenerate damaged tissue. They also secrete cytokines, chemokines, and growth factors that help in tissue repair.
Differentiation of mesenchymal stem cells
Mesenchymal stem cells are multipotent stem cells and can differentiate into chondrocytes, osteoblasts, adipocytes, myocytes and tenocytes.
Chondrogenesis is the formation of cartilage tissue, which is important for the repair of skeletal tissues.
MSCs differentiate into chondrocytes, the specialized cells that are responsible for the formation of cartilage. Chondrocytes secrete molecules (like collagen) that make up the extracellular cartilage matrix that connects and supports musculoskeletal tissues.
Mesenchymal stem cells play a central role in repairing broken bones by breaking into Osteoblasts. Osteoblasts are specialized cells responsible for creating new bone tissue and secreting molecules that contribute to the bone matrix.
MSCs can also differentiate by shape Fat cells (AKA fat cells). Adipocytes are the main component of Adipose tissue, they are therefore essential for the formation of new adipose tissue.
Myoblasts play a central role Myogenesis, or building muscle. When a muscle is damaged, MCSs migrate to the site of the injury, where they differentiate into myoblasts. The myoblasts can fuse with damaged myofibers in the muscles or fuse into myotubes. The myotubes will eventually mature and form new muscle fibers.
Tenogenesis is the formation of tendon tissue and is initiated when MSCs differentiate Tenocytes. Tenocytes are specialized cells that secrete collagen molecules that aggregate into collagen fibrils. A group of collagen fibrils forms a collagen bundle, a group of collagen bundles forms a fascicle, and a group of fascicles forms a tendon.
Mesenchymal stem cells and inflammation
MSCs also act as immunosuppressive cells with powerful anti-inflammatory functions. By releasing cytokines and chemokines, MSCs can suppress almost all cells of the innate and adaptive immune system. This helps maintain immune homeostasis and promotes immune tolerance, thereby preventing unnecessary or excessive activation of the immune system.
Clinical applications for mesenchymal stem cells
The ability of MCS to self-renew and differentiate into different cell types offers enormous potential in the field of regenerative medicine. MSC therapies are not currently available, but research into their potential uses is ongoing, and they could eventually be used in bone and cartilage repair, heart and blood vessel repair, and the treatment of a variety of other diseases.
Bone and cartilage repair
MSCs can differentiate into osteoblasts and chondrocytes, both of which are important for bone and cartilage healing. Hence, MSCs could be used to treat otherwise difficult-to-repair bone and cartilage injuries.
Another potential use of MSCs is for cartilage regeneration, which could improve symptoms of osteoarthritis. Osteoarthritis is a chronic condition in which the cartilage that normally cushions the ends of bones is worn out. Studies have shown that injecting MSC into the affected joints of osteoarthritis patients increases cartilage thickness, reducing pain and other symptoms.
Repair of the heart and blood vessels
Recent studies with MSCs suggest that these stem cells may also contribute to the formation of new blood vessels (a process known as Neovascularization). Eventually, if MSCs can be used to reconstruct blood vessels in the heart, they could be used to treat ischemic heart disease.
Treatment of inflammatory diseases
As immunosuppressive cells, MSCs can also be useful for the treatment of inflammatory diseases such as graft-versus-host reaction (GVHD), sepsis, and irritable bowel syndrome (IBS). However, research in this area is ongoing.
Mesenchymal stem cells vs. hematopoietic stem cells
Mesenchymal and hematopoietic stem cells are both found in the bone marrow, but differentiate into different cell types. Hematopoietic stem cells are blood stem cells and result in different types of blood cells (including red blood cells, white blood cells, and platelets).