Stem Cells

PRP Therapy Explained: How Platelet-Rich Plasma Works and What It Treats

Written by dr-sarah-chen|Updated 2026-04-01|8 min read

PRP therapy has become one of the most widely used regenerative medicine treatments in the world. It is simpler, cheaper, and more accessible than stem cell therapy, and for many conditions, the evidence supporting it is actually stronger. Understanding what PRP can and cannot do will help you determine whether it is the right treatment for your situation.

What Is PRP?

Platelet-rich plasma is exactly what the name describes: a concentration of your own platelets suspended in a small volume of plasma.

Platelets are best known for their role in blood clotting, but they also contain hundreds of bioactive proteins called growth factors. When activated, platelets release these growth factors in a coordinated burst that initiates the body's natural healing cascade.

Key Growth Factors in PRP

Growth FactorFunction
PDGF (Platelet-Derived Growth Factor)Stimulates cell proliferation, angiogenesis, collagen production
TGF-beta (Transforming Growth Factor)Regulates inflammation, promotes tissue remodeling
VEGF (Vascular Endothelial Growth Factor)Promotes new blood vessel formation
EGF (Epidermal Growth Factor)Stimulates cell growth and differentiation
IGF-1 (Insulin-like Growth Factor)Promotes tissue repair and growth
FGF (Fibroblast Growth Factor)Stimulates fibroblast activity and wound healing

By concentrating these factors to 3-8 times their normal blood levels, PRP delivers a potent regenerative signal to damaged tissue.

The PRP Preparation Process

Step 1: Blood Draw

A standard venous blood draw of 15-60 mL (about 1-4 tablespoons), depending on the system used and the volume of PRP needed.

Step 2: Centrifugation

The blood is placed in a specialized centrifuge that separates it into three layers:

  • Top layer: Platelet-poor plasma (PPP)
  • Middle layer: Platelet-rich plasma (the "buffy coat") — this is the PRP
  • Bottom layer: Red blood cells

Step 3: Collection

The PRP layer is carefully extracted. Depending on the system, this yields approximately 3-8 mL of concentrated PRP.

Step 4: Activation (Optional)

Some protocols activate the platelets with calcium chloride or thrombin before injection to initiate growth factor release. Others inject the PRP in its non-activated form, allowing the body's natural environment to trigger activation.

Step 5: Injection

The PRP is injected into the target tissue, often under ultrasound guidance for joint and tendon applications.

Total procedure time: 30-60 minutes.

Not All PRP Is Created Equal

One of the biggest sources of confusion in PRP therapy is that preparation methods vary significantly, and these differences affect outcomes.

Leukocyte-Rich (LR-PRP) vs. Leukocyte-Poor (LP-PRP)

  • LR-PRP contains white blood cells along with platelets. The white blood cells add inflammatory mediators that may be beneficial for chronic tendon problems but harmful in joints.
  • LP-PRP filters out most white blood cells, creating a less inflammatory product that appears to work better for intra-articular (joint) injections.

Platelet Concentration

Higher is not always better. The therapeutic window appears to be approximately 3-8 times baseline platelet concentration. Concentrations above this range may actually be inhibitory.

Single-Spin vs. Double-Spin Systems

Double-spin systems generally produce higher and more consistent platelet concentrations. The specific system used matters.

Applications with Strong Evidence

Knee Osteoarthritis

PRP has the most robust evidence base for knee OA. A 2019 Cochrane review and multiple subsequent RCTs confirm:

  • PRP outperforms hyaluronic acid and saline placebo for pain relief
  • LP-PRP appears superior to LR-PRP for joint injections
  • Effects typically last 6-12 months
  • Most effective for mild-to-moderate OA (KL grade I-III)

Typical protocol: 1-3 injections spaced 2-4 weeks apart.

Tennis Elbow (Lateral Epicondylitis)

Multiple RCTs show PRP outperforms cortisone injection at 6 and 12 months. While cortisone provides faster initial relief, PRP produces better long-term outcomes and actually promotes tendon healing rather than masking symptoms.

Plantar Fasciitis

PRP injection has shown significant improvement in chronic plantar fasciitis that has failed conservative treatment. Results are comparable to cortisone at 3 months but superior at 6 and 12 months.

Hair Restoration

PRP for androgenetic alopecia (pattern hair loss) has growing evidence:

  • Increased hair density of 20-30% in responders
  • Improved hair thickness and coverage
  • Typically requires 3-4 initial sessions spaced 4-6 weeks apart
  • Maintenance sessions every 6-12 months
  • Works best for thinning hair, not complete baldness

Applications with Moderate Evidence

Rotator Cuff Tendinopathy

Promising for partial-thickness tears and chronic tendinitis. May enhance healing after surgical repair. Evidence is growing but not yet definitive.

Achilles Tendinopathy

Mixed results in clinical trials. May be more effective for chronic insertional tendinopathy than mid-substance disease.

Facial Rejuvenation (Vampire Facial)

PRP combined with microneedling has shown improvements in:

  • Fine lines and wrinkles
  • Skin texture and tone
  • Acne scarring
  • Under-eye dark circles

The evidence base includes several small RCTs showing benefit over microneedling alone.

Sexual Health

  • PRP for ED (P-Shot): Early evidence suggests improvement in erectile function, particularly when combined with shockwave therapy
  • PRP for female sexual dysfunction (O-Shot): Very limited evidence, mostly case reports

Applications with Weak Evidence

  • Acute muscle tears (may actually slow healing)
  • Fracture healing
  • ACL reconstruction enhancement
  • Spinal disc degeneration
  • Carpal tunnel syndrome

PRP vs. Stem Cell Therapy

FactorPRPStem Cell Therapy
Cell contentGrowth factors onlyLiving stem cells + growth factors
SourceYour own bloodBone marrow, fat, or donor tissue
Procedure complexitySimple blood drawMay require aspiration or liposuction
Cost per treatment$500-$1,500$3,000-$10,000+
Evidence levelModerate-strong for key applicationsModerate for joint applications
Duration of effect6-12 months12-24 months
Tissue regeneration potentialLimited (signaling only)Higher (cells + signaling)
Ideal forMild-moderate conditions, maintenanceModerate conditions, longer-lasting effect

What to Expect After PRP Treatment

Joint Injection

  • Mild swelling and stiffness for 2-5 days
  • Avoid NSAIDs for 2 weeks (they inhibit platelet function)
  • Light activity by week 1, progressive return to full activity by week 3-4
  • Maximum benefit typically at 6-12 weeks

Tendon Injection

  • Moderate soreness at injection site for 3-7 days
  • Relative rest of the affected tendon for 2 weeks
  • Progressive loading with physical therapy starting at week 2-3
  • Full recovery timeline: 6-12 weeks

Hair Restoration

  • Mild scalp tenderness for 24-48 hours
  • No downtime required
  • Initial shedding may occur (normal)
  • Visible improvement at 3-6 months

The Bottom Line

PRP therapy is the most accessible, affordable, and evidence-supported regenerative medicine treatment available in 2026. It is not a miracle cure, but for the right conditions — knee OA, chronic tendinopathy, hair loss, and skin rejuvenation — it delivers measurable, clinically meaningful results at a fraction of the cost of stem cell therapy.

If you are considering regenerative medicine, PRP is often the logical starting point before moving to more complex and expensive stem cell therapies.

Frequently Asked Questions

Medical Disclaimer

This content is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any new treatment or protocol. Read our full medical disclaimer.