Extracellular Matrix Overview

Extracellular Matrix

• The extracellular matrix (ECM) is the material that lies between cells in multicellular organisms.
• The ECM is made up of fibrous structural proteins, proteoglycans, and adhesive glycoproteins.
• ECM is present in varying amounts depending on tissue type.
• Load-bearing tissues like artery walls, tendons, cartilage, skin, and bone have a higher ratio of ECM to cells (10:1).
• Muscles have a lower ratio of ECM to cells (1:10).
• The physical nature of ECM varies greatly.
• Bone ECM is thick, highly mineralized, hard, inflexible, and opaque.
• The cornea's ECM is water-rich, transparent, flexible, and acts as a gel.
• ECM functions include space filling, mechanical support, cellular interaction for maintaining normal tissue architecture, cell proliferation control, and tissue regeneration.

Fibrous Structural Proteins

• Collagen is the most abundant protein in the human body and provides strength and resilience to tissues.
• Elastin allows tissues to stretch and recoil, much like a rubber band.
• UV light can damage elastin fibers, causing wrinkles in the skin.
• Collagen plays a crucial role in wound healing by tissue remodeling.
• The synthesis of collagen requires ascorbic acid (vitamin C).
• Collagen production slows down with age, leading to skin wrinkles and loss of firmness.

Proteoglycans

• Proteoglycans are a ground substance in the ECM, providing compression resistance and lubrication.
• Examples of proteoglycans include chondroitin sulfate and keratin sulfate.

Adhesive Glycoproteins

• Adhesive glycoproteins like fibronectin and laminin attach cells to the matrix.

Other Key Points

• Collagen synthesis can be reduced by decreased ascorbic acid or increased collagenases.
• Collagen injection, topical collagen creams, antioxidants, and retinoids can be used to restore skin volume and decrease wrinkles.
• Collagen and elastin contribute significantly to the integrity and function of various tissues.