Stromal glycosaminoglycan and proteoglycan fixed charges (FCD)

Stromal glycosaminoglycan and proteoglycan fixed charges refer to the net negative electrical charge density within the extracellular matrix, primarily generated by the sulfate and carboxyl groups of glycosaminoglycans (GAGs) such as keratan sulfate and chondroitin sulfate (Maroudas, 1979). These fixed charges play a critical role in maintaining tissue hydration and structural integrity through the Donnan effect, which creates an osmotic pressure gradient that draws water into the stroma (Hodson, 1971). In the cornea, this balance is essential for transparency, while in cartilage, it provides compressive resistance. Pathological changes in fixed charge density are associated with conditions like corneal edema, osteoarthritis, and increased interstitial fluid pressure in solid tumors, which can hinder drug delivery (Heldin et al., 2004). Therapeutic strategies often involve modulating these charges using osmotic agents like hypertonic saline or enzymes like chondroitinase to alter tissue permeability and fluid dynamics (Netti et al., 2000). Understanding these charges is vital for developing treatments that manage fluid distribution and enhance the penetration of macromolecular drugs into dense stromal environments.

Other names

Fixed charge densityStromal negative charge densityExtracellular matrix fixed chargesGAG-associated fixed charges

Modulation of the Donnan equilibrium and osmotic pressure to regulate fluid flux and interstitial transport.