Hyaluronic acid matrix in the extracellular space (HA)

Hyaluronic acid (hyaluronan) is a large, linear glycosaminoglycan composed of repeating disaccharide units (D-glucuronic acid and N-acetyl-D-glucosamine). It is a critical structural and functional component of the extracellular matrix, providing a hydrated, space-filling environment that supports tissue architecture, regulates cell migration and proliferation, and orchestrates tissue remodeling during development, regeneration, and pathology. The physical properties, molecular weight, and interactions of HA with proteoglycans and cell-surface receptors (e.g., CD44, RHAMM) underlie its diverse biological roles, including modulation of synaptic plasticity, neuronal activity, immune responses, and wound healing. HA matrix composition and its breakdown products are highly context-dependent and can have pro- or anti-inflammatory, angiogenic, or tissue-protective functions, making it central to both normal physiology and disease mechanisms—most notably cancer, inflammation, and neurodegeneration. Therapeutically, exogenous HA and hyaluronidase are used in arthritis, tissue repair, and surgery, but clinical manipulation of HA matrices must balance structural integrity with biological activity and avoid unintended tissue destabilization or immune activation.

Other names

HyaluronanHyaluronic acidHA-rich extracellular matrixPerineuronal net (when discussing condensed ECM in the CNS)HA matrix

Hyaluronidase: enzymatic cleavage and breakdown of HA, remodeling ECM and facilitating permeabilization and cell migration. Exogenous HA: supplementation to increase matrix hydration, promote tissue regeneration, and reduce inflammation. Retinoic acid: upregulates HA synthesis in skin, promoting hydration and repair. Matrikine/matricryptin release following ECM breakdown: bioactive fragments modulate cell behavior and inflammation.