Examples of Mesenchymal Cells in Humans and Their Specific Functions
Mesenchymal cells in humans include osteoblasts, chondrocytes, adipocytes, and myocytes, each with distinct functions in tissue formation, repair, and homeostasis. 1
Mesenchymal Stem/Stromal Cells (MSCs)
MSCs are multipotent progenitor cells that serve as the source of various specialized mesenchymal cells:
- MSCs are rapidly proliferating, multipotent connective tissue progenitor cells found throughout the body, particularly in bone marrow, adipose tissue, and peripheral blood 1
- They express specific cell surface markers (CD73, CD90, and CD105) and lack hematopoietic markers 1
- MSCs can be harvested from bone marrow, abdominal fat, skeletal muscle, and other tissues for therapeutic applications 1
- Their primary functions include immunomodulation, neurotrophic factor secretion, and pro-angiogenic signaling 1
Differentiated Mesenchymal Cell Types and Functions
1. Osteoblasts/Osteocytes
- Differentiate from MSCs to form bone tissue 2
- Osteoblasts synthesize bone matrix proteins and regulate mineralization 2
- Osteocytes develop from osteoblasts and function as mechanosensors in bone 2
- They regulate bone remodeling through signaling to osteoblasts and osteoclasts 2
2. Chondrocytes
- Develop from MSCs to form and maintain cartilage 3
- Produce cartilage extracellular matrix components including collagen and proteoglycans 4
- Maintain joint integrity and provide cushioning at articulating surfaces 4
- Critical for skeletal development during growth 3
3. Adipocytes
- Differentiate from MSCs to form adipose tissue 5
- Store energy in the form of lipids 6
- Secrete hormones that regulate metabolism and energy homeostasis 6
- Provide insulation and mechanical protection to organs 5
4. Myocytes/Muscle Cells
- Develop from MSCs to form skeletal muscle tissue 5
- Contract to generate force for movement 6
- Contribute to metabolic regulation 5
- Participate in tissue repair after injury 6
5. Fibroblasts/Myofibroblasts
- Differentiate from MSCs to produce extracellular matrix components 5
- Secrete collagen and other proteins essential for connective tissue structure 5
- Play critical roles in wound healing and tissue repair 5
- Myofibroblasts contribute to tissue contraction during wound closure 5
6. Perivascular Cells
- Mesenchymal cells that surround blood vessels 1
- Support endothelial cells in vascular network formation 1
- Contribute to vessel stability and maturation 1
- Some perivascular cells may represent tissue-resident MSC populations 1
Clinical Applications
Mesenchymal cells have significant therapeutic potential:
- MSCs can be used in cell-based therapies for tissue regeneration and repair 3
- They can be expanded ex vivo while maintaining their differentiation potential 5
- MSCs are being investigated for treatment of spinal cord injuries, multiple sclerosis, and arthritis 1
- Bone marrow-derived MSCs are being tested in clinical trials for various conditions including spinal cord injury 1
Important Considerations
- The differentiation capacity of mesenchymal cells decreases with donor age 3
- Strict regulation of differentiation is essential for therapeutic success 3
- The term "stem cell" has been overused for minimally manipulated cell preparations 1
- No MSC therapies have yet been FDA-cleared for human clinical application to musculoskeletal diseases 1