PRP vs Stem Cell Therapy: What’s the Difference?

Biologic therapies have become a major focus of orthopedic research and are increasingly sought after by patients exploring new options for musculoskeletal care. Platelet-rich plasma (PRP) and stem cell therapy lead that interest, with patients asking about both options for joint pain, tendon and ligament injuries, muscle tears, and degenerative conditions.

The two are often mentioned together, and they do share the goal of working with the body’s own biology. They are, however, different therapies that use different biologic material and work through different mechanisms and pathways.

Some useful questions a patient may want to consider before pursuing platelet-rich plasma or stem cell therapy include:

• What is causing pain, restricting function, or limiting healing?
• How advanced is the injury or the degeneration?
• Is there supporting evidence that suggests PRP or stem cell therapy can be used in my situation?
• Which option best fits the patient’s goals and situation?

Dr. Steve Yoon is a sports medicine and regenerative medicine physician who has worked with professional sports organizations and athletes in Los Angeles and around the country for over 15 years. The guide below is an objective overview of both therapies.

What is PRP?

PRP, or platelet-rich plasma, is from a patient’s own blood. After a routine blood draw, the sample is processed in a centrifuge to concentrate platelets, typically to approximately two to five times their normal concentration. The resulting platelet-rich plasma is then injected into the injured joint, tendon, ligament, or muscle using image guidance.¹

PRP does not contain stem cells. Platelets work by releasing a large number of biologically active proteins involved in tissue repair and healing, including growth factors, cytokines, and signaling molecules. Research also suggests PRP has anti-inflammatory and chondroprotective effects, meaning it may help protect remaining cartilage within an arthritic joint while improving symptoms.²

Among patients with knee osteoarthritis, randomized controlled trials and systematic reviews have shown improvements in pain and function compared with placebo injections and with hyaluronic acid (viscosupplementation).^3,4

PRP is a straightforward outpatient procedure involving a basic blood draw. Published research reports that results can vary with how PRP is prepared. A 2025 meta-analysis of placebo-controlled trials in knee osteoarthritis found that platelet concentration influenced pain and function results,⁹ and a systematic review of the orthopedic literature found that PRP preparation protocols are reported inconsistently across studies.¹⁰

What is Stem Cell Therapy?

Mesenchymal stem cells (MSCs), under appropriate conditions, can differentiate toward bone, cartilage, and other soft tissues.⁵ Current research has focused on their ability to function largely as signaling cells.⁵ They are described as communicating with the cells around them through a network of biologically active molecules.⁵ In the published literature, these effects are described as paracrine activity and include the release of cytokines, growth factors, extracellular vesicles, and other molecules that have been studied for their role in regulating inflammation and tissue repair.^5,14 MSCs are also described as having immunomodulatory effects, meaning they can influence immune activity.^5,14

Because osteoarthritis (OA) involves chronic inflammation alongside cartilage degeneration, researchers hypothesize that this signaling function is part of why stem cell therapy may be effective for OA, making it one of the most active areas of regenerative medicine research.⁵

The published trial results are encouraging. A 2025 meta-analysis of randomized controlled trials found statistically significant improvement in pain and function scores at both 6 and 12 months in patients with knee osteoarthritis who received stem cell injections, with adverse event rates comparable to controls.⁶ A 2025 Cochrane review of trials comparing stem cell injection against placebo reported pain scores 1.2 points better on a 10-point scale at six months, function scores 14.2 points better on a 100-point scale, and a successful outcome reported by 68 percent of stem cell patients versus 53 percent of placebo patients.⁷ A long-term randomized trial of bone marrow-derived MSCs reported benefits sustained at four years.⁸

Stem cell therapy is not one single, standardized approach. Studies differ in cell source, processing method, cell count, patient selection, injection technique, and outcome measures, which is part of why research continues to evaluate which approaches work best for certain situations.

At a Glance: PRP vs. Stem Cell Therapy

Measure	PRP	Stem Cell (Mesenchymal Stem Cells)
What is it	Concentrated platelets and growth factors from a patient’s own blood	Stromal cells (autologous or donor) acting primarily via paracrine and immunomodulatory effects
Contains stem cells	No	Yes, in variable amounts depending on the type of therapy
Evidence	Most-studied orthobiologic; outperformed placebo and viscosupplementation in several randomized trials for knee osteoarthritis.1,3,4	Studied in knee osteoarthritis; randomized trials report improvement versus control, though overall certainty was rated low in a 2025 Cochrane review.6,7
Invasiveness	Low; routine blood draw	Higher for autologous therapy requiring bone marrow aspiration or fat harvest; minimal for donor-derived stem cells
Relative Cost	Lower	Higher

Conditions Studied in Research

Published research on PRP and stem cell therapy spans a wide range of orthopedic problems,¹³ including:

• Joints: Osteoarthritis, cartilage damage, labrum tears, meniscus tears, joint swelling
• Tendons: rotator cuff partial tears, tennis elbow and golfer’s elbow, patellar and hamstring tendinopathy, Achilles tendinopathy and partial tears
• Ligaments: sprains and partial tears
• Muscle: strains and partial tears

Platelet-rich plasma has been researched more than stem cell therapy, although clinical studies have been documented for both over the last several decades. Many of these biologic therapies have focused more on degenerative joint disease, such as osteoarthritis, as well as tendinopathies. Published medical literature can help guide physicians when deciding whether PRP or stem cell therapy is appropriate.

Which Therapy Is Right for You?

In clinical practice, physicians commonly review several factors when discussing biologic therapy options, including:

• The diagnosis
• Severity of condition
• Prior therapies tried
• Surgical history
• Age and activity level
• Budget and tolerance for more invasive procedures
• Patient goals and expectations

Image guidance is also commonly used during these procedures. A systematic review of randomized trials found that ultrasound-guided knee injections were more accurate than blind injections.¹²

Where This Leaves Patients

PRP and stem cell therapy are complementary approaches rather than competing ones. PRP is simpler, uses predictable mechanisms of action, is less expensive, and has a substantial body of clinical research supporting its use. Stem cell therapy is described in the literature as acting through cell signaling and immune modulation,^5,14 and randomized trials in knee osteoarthritis have reported improvement in pain and function compared with control,^6,7 with research continuing with other orthopedic conditions.¹³

Deciding which form of therapy is appropriate may involve understanding the diagnosis, the severity of the condition, physical ability, and the patient’s goals. A physician experienced with both therapies can review these factors as part of a comprehensive evaluation and developing a plan of care.

To schedule a consultation to discuss PRP or stem cell therapy, please contact Dr. Yoon’s practice here.

Frequently Asked Questions

Is PRP or stem cell therapy better for knees?

A randomized trial comparing PRP with bone marrow aspirate concentrate (BMAC) in knee osteoarthritis reported similar improvements in pain and function between groups at one year.¹¹ Comparative data between the two remains limited, and the trials that do exist differ in preparation method and patient selection.

PRP is often less expensive and has a large overall body of evidence supporting its use. Stem cell therapy continues to be studied in knee osteoarthritis,^6,7 and options are typically reviewed with a physician based on each person’s needs.

What is the difference between PRP and stem cell injections?

PRP provides growth factors from your own blood. It does not contain stem cells. Stem cell therapy works primarily through cell signaling, paracrine activity, and immune modulation.

Although both are considered orthobiologic injections, they work through different biological mechanisms.

How long do the results last?

Published trials report outcomes over different follow-up periods. A meta-analysis of placebo-controlled PRP trials in knee osteoarthritis reported results through 12 months,⁹ and a randomized trial of bone marrow-derived MSCs reported results at four years of follow-up.⁸ Reported durations vary across studies.

References

1. American Academy of Orthopaedic Surgeons. (2021). Management of osteoarthritis of the knee (non-arthroplasty): Clinical practice guideline (3rd ed.).

2. Sundman EA, Cole BJ, Karas V, Della Valle C, Tetreault MW, Mohammed HO, Fortier LA. “The anti-inflammatory and matrix restorative mechanisms of platelet-rich plasma in osteoarthritis.” American Journal of Sports Medicine. 2014 Jan;42(1):35-41.

3. Belk JW, Lim JJ, Keeter C, McCulloch PC, Houck DA, McCarty EC, Frank RM, Kraeutler MJ. “Patients With Knee Osteoarthritis Who Receive Platelet-Rich Plasma or Bone Marrow Aspirate Concentrate Injections Have Better Outcomes Than Patients Who Receive Hyaluronic Acid: Systematic Review and Meta-analysis.” Arthroscopy. 2023 Jul;39(7):1714-1734.

4. Costa L, et al. (2022). “How Does Platelet-Rich Plasma Compare Clinically to Other Therapies in the Treatment of Knee Osteoarthritis? A Systematic Review and Meta-analysis.” The American Journal of Sports Medicine, 51(5), 1407-1420.

5. Caplan AI. “Mesenchymal Stem Cells: Time to Change the Name!” Stem Cells Translational Medicine. 2017;6(6):1445-1451.

6. Cao M, Ou Z, Sheng R, et al. “Efficacy and safety of mesenchymal stem cells in knee osteoarthritis: a systematic review and meta-analysis of randomized controlled trials.” Stem Cell Research & Therapy, 16, 122 (2025).

7. Whittle SL, Johnston RV, McDonald S, et al. “Stem cell injections for osteoarthritis of the knee.” Cochrane Database of Systematic Reviews, 2025, Issue 4, Art. No. CD013342.

8. Lamo-Espinosa JM, Mora G, Blanco JF, et al. “Intra-articular injection of two different doses of autologous bone marrow mesenchymal stem cells versus hyaluronic acid in the treatment of knee osteoarthritis: long-term follow-up of a multicenter randomized controlled clinical trial.” Journal of Translational Medicine, 16, 213 (2018).

9. Bensa A, Previtali D, Sangiorgio A, Boffa A, Salerno M, Filardo G. “PRP Injections for the Treatment of Knee Osteoarthritis: The Improvement Is Clinically Significant and Influenced by Platelet Concentration: A Meta-analysis of Randomized Controlled Trials.” The American Journal of Sports Medicine. 2025;53(3):745-754. doi:10.1177/03635465241246524

10. Chahla J, Cinque ME, Piuzzi NS, Mannava S, Geeslin AG, Murray IR, Dornan GJ, Muschler GF, LaPrade RF. “A Call for Standardization in Platelet-Rich Plasma Preparation Protocols and Composition Reporting: A Systematic Review of the Clinical Orthopaedic Literature.” The Journal of Bone and Joint Surgery. American Volume. 2017;99(20):1769-1779. doi:10.2106/JBJS.16.01374

11. Anz AW, et al. “Bone Marrow Aspirate Concentrate Is Equivalent to Platelet-Rich Plasma for the Treatment of Knee Osteoarthritis at 1 Year: A Prospective, Randomized Trial.” Orthopaedic Journal of Sports Medicine. 2020;8(2):2325967119900958. doi:10.1177/2325967119900958

12. Fang WH, Chen XT, Vangsness CT Jr. “Ultrasound-Guided Knee Injections Are More Accurate Than Blind Injections: A Systematic Review of Randomized Controlled Trials.” Arthroscopy, Sports Medicine, and Rehabilitation. 2021;3(4):e1177-e1187. doi:10.1016/j.asmr.2021.01.028

13. Goulian AJ, Goldstein B, Saad MA. “Advancements in Regenerative Therapies for Orthopedics: A Comprehensive Review of Platelet-Rich Plasma, Mesenchymal Stem Cells, Peptide Therapies, and Biomimetic Applications.” Journal of Clinical Medicine. 2025;14(6):2061. doi:10.3390/jcm14062061

14. Han X, et al. “Mesenchymal stem cells in treating human diseases: molecular mechanisms and clinical studies.” Signal Transduction and Targeted Therapy. 2025. doi:10.1038/s41392-025-02313-9