In our earlier post titled “PRP 101”, we looked at Platelet Rich Plasma (PRP) and gained a general understanding of its use and benefits in veterinary medicine. Today we are going to look a little closer at the key components that provide these benefits, growth factors.
Growth factors are small proteins that are contained within a compartment inside the platelet called the alpha granule. When a platelet is exposed to an area of damage or to fibrinogen, it becomes activated and changes its shape so that the alpha granule releases its growth factors. These growth factors play an important role in tissue repair and healing because they attract other cell types to the area that in turn clean up and rebuild the tissue.
The “original” growth factor that was first discovered in platelets is Platelet Derived Growth Factor (PDGF). PDGF acts in several different capacities and is most commonly known for its role in blood vessel formation (angiogenesis). PDGF also has the ability to attract macrophages to an area of damage to begin the clean-up of injured or necrotic tissue. Additionally, PDGF prompts macrophages to release additional growth factors into the tissue.
Another notable growth factor is Transforming Growth Factor Beta (TGF-β). TGF-β is known to synthesize and preserve the extracellular matrix which can include Hyaluronic Acid (HA), chondroitin sulfate and collagen. These components of the extracellular matrix are vital for maintaining elastic, fluid moving joints. This is increasingly important for joints that have a reduced joint space or eroded cartilage as seen in osteoarthritis. In addition to this, TGF-β has also shown to act as a scaffold for cartilage regeneration both in vitro and in vivo.
With several other growth factors found in platelets including Insulin-like Growth Factor (IGF), Vascular Endothelial Growth Factor (VEGF), Fibroblastic Growth Factor (FGF) and Epidermal Growth Factor (EGF), tissue repair and healing can be done at an accelerated rate. Whether it is an arthritic joint that needs additional synovial components or a ligament injury in need of repair, platelets and their growth factors have been shown to be vital in the healing process.
Stay tuned for our next blog post where we discuss indications for using PRP.
