The term “mesenchymal” refers to a specific type of cell and tissue important for the body’s development and ongoing maintenance. Mesenchymal cells are multipotent stem cells, meaning they possess the ability to develop into various specialized cell types. They contribute to the formation and repair of many bodily structures, making their capacity for differentiation significant in biological processes.
Understanding Mesenchymal Cells
Mesenchymal cells, often called mesenchymal stem cells (MSCs) or mesenchymal stromal cells, are multipotent adult stem cells. They can differentiate into several distinct cell lineages, including osteoblasts (bone cells), chondrocytes (cartilage cells), adipocytes (fat cells), and myocytes (muscle cells).
MSCs are found in numerous adult tissues throughout the body, such as bone marrow, adipose (fat) tissue, and umbilical cord blood. These spindle-shaped cells exhibit a fibroblast-like morphology and adhere to plastic surfaces in laboratory settings. They also express specific surface markers like CD73, CD90, and CD105, while lacking others such as CD11b, CD14, CD34, and CD45, which aids in their identification.
Mesenchyme Tissue and Embryonic Development
The term “mesenchyme” refers to a type of embryonic connective tissue composed of loosely organized, undifferentiated cells within an extracellular matrix. This tissue primarily originates from the mesoderm, one of the three germ layers that form early in embryonic development. A small amount of mesenchyme also arises from the ectoderm, specifically from a structure called the neural crest.
The loose and fluid nature of mesenchyme allows its cells to migrate easily, a key feature during embryonic and fetal development. This tissue serves as a precursor for the majority of the body’s connective tissues, including bones, cartilage, fat, and the lymphatic and circulatory systems. Mesenchyme’s interactions with epithelial tissue are also important in the formation of nearly every organ in the developing embryo. While mesenchyme is largely a transient tissue during development, mesenchymal cells persist in small quantities in adult organisms within tissues like bone marrow, fat, and muscles.
Roles of Mesenchymal Cells in the Body
Mesenchymal cells contribute to the maintenance and repair of tissues throughout an individual’s life. These cells function as structural support in organs and regulate the movement of substances.
Mesenchymal cells also have immunomodulatory properties, meaning they can influence the immune system. They achieve this by secreting various bioactive factors that reduce inflammation and promote healing. These secreted factors include growth factors like hepatocyte growth factor (HGF), insulin-like growth factor (IGF-1), and vascular endothelial growth factor (VEGF), which support cell survival and tissue regeneration. Mesenchymal cells also migrate towards sites of injury or infection, guided by chemical signals.
Therapeutic Potential of Mesenchymal Cells
Mesenchymal cells hold promise in regenerative medicine due to their capacity for differentiation and immunomodulatory capabilities. They are being investigated for repairing damaged tissues such as cartilage, bone, and muscle, and for supporting the regeneration of organs like the heart and liver. MSCs can be isolated from sources like bone marrow, adipose tissue, or umbilical cord tissue, and then expanded in laboratory cultures for therapeutic use.
Their ability to modulate immune responses makes them appealing for treating autoimmune and inflammatory conditions, such as rheumatoid arthritis, multiple sclerosis, and Crohn’s disease. Research also involves combining mesenchymal cells with biomaterials to create engineered tissues for repair applications. Their accessibility and relatively low risk of immune rejection make them attractive candidates for medical advancements.