Platelet-Rich Plasma (PRP) for Joint Regeneration

Platelet-rich plasma (PRP) therapy is one of the most established autologous regenerative treatments available today. By concentrating the patient’s own platelets and growth factors, PRP harnesses the body’s natural healing mechanisms to support tissue repair and regeneration. This article examines the science behind PRP therapy, its mechanisms of action in joint regeneration, and the clinical evidence supporting its use in osteoarthritis and related conditions.

What Is Platelet-Rich Plasma?

PRP is a concentrated preparation of platelets derived from the patient’s own blood. A small volume of blood is drawn (typically 15–60 millilitres) and processed in a centrifuge to separate the blood components. The resulting PRP contains a platelet concentration three to five times higher than normal circulating blood.

Platelets are best known for their role in blood clotting, but they also contain dense granules packed with growth factors, cytokines, and other bioactive molecules that play central roles in tissue repair. When PRP is injected into a damaged joint, these concentrated growth factors are released into the local tissue environment, initiating and amplifying the body’s natural healing response.

The Growth Factor Payload

The therapeutic activity of PRP is primarily driven by the growth factors stored within platelet alpha-granules. Key growth factors released upon platelet activation include:

Platelet-derived growth factor (PDGF): Stimulates cell proliferation, chemotaxis (cell migration to the injury site), and new blood vessel formation. PDGF is one of the first growth factors released at sites of tissue damage.

Transforming growth factor beta (TGF-β): Plays critical roles in cell differentiation, extracellular matrix production, and immunomodulation. TGF-β is particularly important in cartilage biology, where it stimulates chondrocyte proliferation and proteoglycan synthesis.

Vascular endothelial growth factor (VEGF): Promotes angiogenesis, the formation of new blood vessels, improving blood supply to areas of tissue damage or degeneration.

Insulin-like growth factor (IGF-1): Supports cell growth, differentiation, and survival. IGF-1 is an important mediator of cartilage homeostasis and repair.

Fibroblast growth factor (FGF): Stimulates the proliferation of fibroblasts and other cell types involved in tissue repair, and plays a role in angiogenesis and wound healing.

Epidermal growth factor (EGF): Promotes cell proliferation and differentiation, contributing to tissue regeneration.

In addition to growth factors, PRP contains anti-inflammatory cytokines (such as interleukin-1 receptor antagonist, IL-1Ra) that can help counteract the inflammatory environment characteristic of osteoarthritic joints.

How PRP Works in Joint Regeneration

When PRP is injected into an osteoarthritic joint, several biological processes are initiated:

Anti-Inflammatory Effects

Osteoarthritis is characterised by chronic low-grade inflammation within the joint, driven by pro-inflammatory cytokines such as interleukin-1β (IL-1β) and tumour necrosis factor alpha (TNF-α). PRP delivers concentrated anti-inflammatory mediators, including IL-1Ra and other regulatory cytokines, that help counterbalance this inflammatory cascade.

By shifting the joint microenvironment from a predominantly inflammatory state towards one more conducive to repair, PRP creates conditions that support cartilage preservation and regeneration.

Cartilage Support

The growth factors within PRP, particularly TGF-β and IGF-1, stimulate chondrocyte metabolism, promoting the production of extracellular matrix components (proteoglycans and type II collagen) that constitute healthy articular cartilage. Whilst PRP is unlikely to regenerate large areas of lost cartilage, it can support the preservation of remaining cartilage and promote repair of smaller defects.

Synovial Environment Improvement

PRP has been shown to improve the quality of synovial fluid within the joint, enhancing viscosity and lubrication. This may contribute to reduced friction, improved joint mechanics, and decreased pain during movement.

Pain Modulation

Beyond its structural effects, PRP may modulate pain through multiple mechanisms, including reducing inflammatory mediators that sensitise pain receptors, promoting the healing of painful subchondral bone lesions, and supporting the repair of damaged synovial tissue.

Clinical Evidence

PRP therapy for osteoarthritis has been the subject of extensive clinical investigation, with dozens of randomised controlled trials and several meta-analyses published in peer-reviewed journals.

Knee Osteoarthritis

The strongest evidence for PRP exists in knee osteoarthritis. A comprehensive meta-analysis published in the Journal of Orthopaedic Research (2019) analysed data from 14 randomised controlled trials and concluded that PRP injections provided superior pain relief and functional improvement compared to hyaluronic acid (viscosupplementation) and placebo at 12-month follow-up.

A subsequent Cochrane-style systematic review (2021) confirmed these findings, noting that PRP produced clinically meaningful improvements in pain and function scores, with a favourable safety profile. The review also noted that leucocyte-poor PRP preparations (containing fewer white blood cells) appeared to produce better outcomes than leucocyte-rich preparations.

Hip and Shoulder Osteoarthritis

Clinical evidence for PRP in hip and shoulder osteoarthritis is more limited than for the knee but growing. Preliminary studies suggest similar trends, reduced pain and improved function, though the evidence is not yet as robust. These joints present greater technical challenges for accurate injection placement, making image guidance particularly important.

Tendon and Ligament Injuries

PRP has also demonstrated efficacy in the treatment of tendon injuries (tendinopathy), with clinical trials showing improved outcomes in conditions such as lateral epicondylitis (tennis elbow), Achilles tendinopathy, and rotator cuff injuries. The growth factor concentration within PRP supports the cellular and matrix repair processes that are often impaired in chronic tendon pathology.

The PRP Procedure

The PRP procedure at Longevity Thailand follows a standardised protocol:

A small volume of blood is drawn from the patient’s arm. The blood is processed in a medical-grade centrifuge to concentrate the platelets. The resulting PRP is prepared for injection. Under ultrasound guidance, the PRP is precisely injected into the target joint or tissue.

The entire procedure typically takes 30 to 45 minutes. Most patients receive a series of two to three injections spaced two to four weeks apart, though the exact protocol varies depending on the severity of the condition and the clinical response.

Safety Profile

Because PRP is derived from the patient’s own blood (autologous), the risk of allergic reaction or immune rejection is negligible. This represents a significant safety advantage over synthetic or allogeneic therapeutic agents.

The most common side effects are mild and transient, including temporary pain, swelling, or stiffness at the injection site. These typically resolve within 24 to 72 hours. Infection is a rare risk associated with any injection procedure and is minimised through sterile technique and clinical best practice.

Realistic Expectations

PRP therapy can provide meaningful improvements in pain and function for many patients with mild to moderate joint degeneration. However, it is not a cure for osteoarthritis, and patients with advanced joint destruction may experience limited benefit.

The most significant improvements are typically observed in patients with early to moderate disease who combine PRP therapy with appropriate rehabilitation, lifestyle modifications, and, where indicated, complementary regenerative treatments such as MSC therapy or exosome therapy.

Response times vary between individuals. Some patients notice improvement within two to four weeks, whilst maximum benefit may not be apparent for three to six months.

PRP Preparation: Why Quality Matters

Not all PRP preparations are equivalent. The concentration of platelets, the presence or absence of leucocytes (white blood cells), and the activation method used can significantly influence therapeutic outcomes.

Leucocyte-rich PRP (LR-PRP) contains a higher concentration of white blood cells, which may introduce additional pro-inflammatory factors. Whilst this may be beneficial in some contexts (such as chronic tendinopathy where a controlled inflammatory stimulus can restart healing), it may be less desirable in conditions already characterised by excessive inflammation, such as osteoarthritis.

Leucocyte-poor PRP (LP-PRP) contains minimal white blood cells and has demonstrated superior outcomes in osteoarthritis clinical trials. The reduced inflammatory load creates a more favourable environment for cartilage preservation and repair.

At Longevity Thailand, we use standardised preparation systems that produce consistent, high-quality PRP with documented platelet concentrations. The choice between leucocyte-rich and leucocyte-poor formulations is made by the treating physician based on the specific clinical indication and the latest evidence.

Integration with Other Regenerative Therapies

PRP therapy is frequently combined with other regenerative modalities to create comprehensive treatment protocols. Common combinations include PRP with mesenchymal stem cell therapy, where PRP provides the growth factor environment that supports MSC engraftment and activity, and PRP with exosome therapy, where the complementary mechanisms of concentrated platelets and targeted molecular signalling work synergistically to promote tissue repair.