Autologous Conditioned Plasma Therapy (ACP)

Platelet concentrates and the place of ACP

A 2009 review by Dohan Ehrenfest and colleagues described several ways of making platelet concentrates and noted that each method gives a different product with different biology and potential uses. The authors proposed four categories based on leukocyte and fibrin content: pure platelet-rich plasma, leukocyte- and platelet-rich plasma, pure platelet-rich fibrin and leukocyte- and platelet-rich fibrin. They described the clinical efficiency of topical platelet concentrates as controversial at that time.

A 2025 cohort study from a UK orthopedic center describes autologous conditioned plasma as a single-spin, leukocyte-poor form of platelet-rich plasma with a platelet concentration estimated at two to three times that of blood. Its authors present ACP as a possible refinement of earlier PRP products, which had been criticized for high leukocyte content. In that study the term referred to plasma prepared with a named commercial double-syringe system.

What the sources do not establish

The sources reviewed for this page do not give a verified date or inventor for ACP, and they do not trace the history of platelet-rich plasma from its first clinical use. Statements about when and where the technique began are therefore left out. What the sources do show is that PRP has been studied across many medical fields, with musculoskeletal conditions making up most of the higher-level clinical trials, as a 2021 review of 132 such studies found.

ACP and platelet-rich plasma

In the literature reviewed, ACP is a type of platelet-rich plasma, not a separate substance. The 2025 cohort study defines it as a leukocyte-poor PRP produced with a single centrifugation step. Systematic reviews and guidelines generally use the broader term PRP, so findings reported for PRP are the main body of evidence available when ACP is discussed, but results for one preparation cannot be assumed to apply to another.

Two further terms recur. Leukocyte-poor PRP and leukocyte-rich PRP describe the white blood cell content of the preparation. In one meta-analysis of adverse events, leukocyte-rich was defined as 1 percent or more leukocytes and leukocyte-poor as less than 1 percent. This page does not cover prolotherapy, which injects an irritant solution such as dextrose and has its own page.

Why naming matters

The 2009 classification was proposed because products labeled as platelet-rich plasma differ in cell content and biology. A 2021 review of 132 level I and II clinical studies across medical specialties found that only 33 percent described the composition of the PRP used and only 17 percent reported its leukocyte component. A name such as ACP on its own therefore tells a reader less about the actual preparation than a stated platelet and leukocyte content would.

General outline

The sources describe PRP-type therapy in general terms. A sample of the person's own blood is processed in a centrifuge to concentrate platelets in a small volume of plasma, and the resulting preparation is injected into a joint or tendon area. The 2025 cohort study describes ACP as a preparation with platelet counts about two to three times those of blood, and it reports a mean platelet concentration of about 588 thousand per microliter in its sample.

Practical details differ between manufacturers, and this page does not describe preparation or injection methods. Authors of a 2026 safety review noted that PRP differs in preparation, dose, leukocyte content, activation and follow-up between trials, and that only 6 of 32 randomized trials gave enough information to analyze platelet dose.

Where the procedure sits in care

In the studies reviewed, injections were given in clinical settings such as orthopedic and sports medicine services, often after other conservative treatment. The sources describe it as an adjunct or alternative to injections such as corticosteroid or hyaluronic acid, not a replacement for diagnosis. Whether it is covered by insurers or public health systems was not addressed by the sources reviewed.

Conditions studied

A review of 132 level I and II PRP studies across eight medical specialties found that most were musculoskeletal and that knee osteoarthritis and tendinopathy were the most studied conditions. Other studied fields included dermatology, oral and maxillofacial surgery, ophthalmology and plastic surgery. A separate meta-analysis of 78 randomized trials covered bone, cartilage and soft tissue conditions treated with or without surgery.

ACP in particular is described in the 2025 cohort study in knee osteoarthritis. The sources reviewed do not provide separate bodies of ACP-specific randomized evidence for other conditions, so uses beyond the knee are discussed here under the wider PRP heading.

Proposed rationale

Proponents hold that concentrated platelets release growth factors that influence inflammation and tissue repair. The sources reviewed treat this as a rationale for research and not as established clinical benefit. The Cochrane-based commentary on soft tissue injuries and the 2019 guideline both frame the effect of PRP as a question for rigorous trials, as described in the next section.

Knee osteoarthritis: placebo-controlled trial and reviews

The RESTORE trial randomized 288 adults aged 50 or older with symptomatic mild to moderate medial knee osteoarthritis to injections of commercially prepared leukocyte-poor PRP or saline placebo, with participants, injectors and assessors blinded. At 12 months knee pain fell by 2.1 points on an 11-point scale with PRP and 1.8 with placebo (difference -0.4, 95% confidence interval -0.9 to 0.2), and cartilage volume change on MRI did not differ. Of 31 secondary outcomes, 29 showed no significant difference between groups.

Pooled analyses are more favorable but vary in comparator. A 2019 meta-analysis of 78 randomized trials (5,308 patients) found pain reductions with PRP of SMD -0.34 at 3 months and -0.60 at 1 year, from low- to moderate-quality evidence, and its authors judged evidence for clinically significant efficacy to be limited. A 2026 network meta-analysis of 21 trials ranked both leukocyte-rich and leukocyte-poor PRP above hyaluronic acid and placebo for function at 6 to 12 months, without evidence to prefer one formulation.

Tendinopathy and other soft tissue injuries

A Cochrane review discussed in a 2015 commentary included 19 randomized or quasi-randomized trials (1,088 patients) of platelet-rich therapies for soft tissue injuries, with comparators such as placebo, whole blood, dry needling or no PRP. It reported small short-term pain improvements, probably not clinically important, no benefit for function, and low-certainty evidence. The commentary concluded that PRP use for these injuries was unsupported at that time and called for larger trials with standardized preparations.

A later sham-controlled trial of 240 adults with chronic midportion Achilles tendinopathy found a mean VISA-A score of 54.4 with a single PRP injection and 53.4 with sham at 6 months (adjusted difference -2.7, 95% CI -8.8 to 3.3), and its authors concluded the findings did not support the treatment. For lateral elbow tendinopathy, a 2026 meta-analysis of six trials (338 participants) comparing PRP with corticosteroid found corticosteroid favored on pain at 4 weeks or less and PRP favored beyond 24 weeks; the authors called the time trend hypothesis-generating.

Guideline position and variation between preparations

The 2019 American College of Rheumatology and Arthritis Foundation guideline strongly recommends against PRP for knee and hip osteoarthritis, citing heterogeneity and lack of standardization in available preparations. It makes no recommendation for hand osteoarthritis. The guideline predates the trials above and states that recommendations should not be used to deny access to therapies.

Whether leukocyte content changes outcomes is unsettled. A 2021 systematic review of 32 studies found both leukocyte-poor and leukocyte-rich PRP exceeded minimal clinically important differences for pain and function with no significant difference between them, while leukocyte-rich PRP had higher odds of post-injection pain and swelling. The 2025 ACP cohort study had no control group and its authors listed this as a key limitation.

Reported adverse events

A 2026 systematic review and meta-analysis of 32 randomized trials (about 1,268 PRP-treated knees) reported adverse events in 18.7 percent of PRP cases, mostly mild knee pain and swelling (10.6 percent), with mild symptoms usually resolving within about two weeks. Mild pain and swelling were more frequent than with hyaluronic acid, a difference confined to leukocyte-rich preparations. Knee stiffness was more frequent than with saline. No infection, hematoma, thrombosis or hemarthrosis was reported. The authors cautioned that trials may underestimate real-world rates and that adverse events were inconsistently defined.

In the Achilles tendinopathy trial, injection-site discomfort at two weeks was reported by 97 of 119 participants given PRP and 73 of 119 given sham, and swelling and bruising were common in both groups. One serious event judged related to the injection occurred in the PRP group: severe pain that resolved after tendon debridement. The preparation in that trial was leukocyte-rich.

Limits of the safety evidence and suitability

The 2025 ACP cohort study did not include a systematic adverse-event report, even though its discussion describes the treatment as safe; that statement is not backed by safety data in the paper. Safety findings from knee trials are not evidence about other body sites, rarer events or long-term outcomes.

The sources reviewed do not provide a list of contraindications or drug interactions, so none is stated here. New or worsening joint pain, swelling with fever, a locked joint or loss of function warrant assessment by a clinician, and injection therapy should not delay or replace necessary diagnosis or conventional care. No professional register, training standard or regulatory status specific to ACP was found in the sources reviewed.