What is Hyaluronic Acid?

Description

• Hyaluronic Acid (“HA”) is a naturally produced substance present throughout the body which binds with water to form a viscous gel
• HA is the primary component of synovial fluid (joint fluid) which can help reduce pain and improve joint function
• The unique combination of biomechanical and biochemical properties makes HA an important molecule for maintaining joint health
• The ability to retain water and its binding to cartilage components are the principal biological functions of HA 

Biomechanical Properties

 Unique biomechanical properties include:

• Joint lubricant
• Joint shock absorber
• Provides a molecular scaffold for many of the components of the cartilage

Biochemical Properties

 Unique Biochemical properties include regulation of:

• Pain (binding the nerve cells to reduce their sensitivity)
• Tissue homeostasis (equilibrium)
• Inflammation

The biochemical activities of HA are regulated by binding to receptors expressed by chondrocytes (cartilage cells) synovialcytes and inflammatory cells.

Function of Hyaluronic Acid

The principal functions of HA are:

• Maintain normal joint structure
• Promote joint healing
• Regulate chondrocytes (cartilage cells) growth and viability
• Stimulate synthesis of articular cartilage components
• Collagen (connective fibres)
• Proteoglycans (components that give cartilage its physical attributes)
• Body’s production of HA
• Suppress the production and activation of enzymes that cause tissue damage
• Inhabit inflammatory cytokines that cause swelling and pain
• Block movements of inflammatory cells that perpetuate the immune response

Cellular Response

The cellular response to HA is dependent on the molecular mass of the HA molecule.

In osteoarthritis affected joints, the concentration and molecular mass of HA is reduced due to:

• Decreased production of HA
• Increased activity of cell degrading enzymes which occur in response to chronic inflammation 

Importance of Molecular Mass

Low molecular weight HA fragments cannot maintain the mechanical integrity of the joint leading to:

• Reduced function
• Increased friction
• Pain

Small HA fragments:

• Promote inflammation by stimulating production of inflammatory cytokines and matrix degrading enzymes
• May impact the ability to activate important cell signalling pathways
• Allows receptors to cluster and initiate a destructive cellular response

Larger HA chains (like those found in healthy cells) block receptor activation and protect the cartilage and joint tissue.

High molecular mass HA is too large to be absorbed orally (must be injected into the joint). Having the optimal HA mass is essential to achieve the biochemical and biomechanical benefits