Standardized Platelet-rich Plasma Research Articles

Impact of Centrifugation Parameters on Platelet-Rich Plasma Injection for Patella Tendinopathy: A Systematic Review and Meta-Analysis.

Patellar tendinopathy (PT) is a chronic, degenerative form of tendinitis commonly affecting young, active individuals. Numerous nonsurgical treatments exist, of which platelet-rich plasma (PRP) is a frontrunner. However, heterogeneity among various PRP preparation techniques results in a large variation in treatment efficacy. This review and meta-analysis aims to investigate the effect of PRP centrifugation factors, specifically centrifuge speed and duration, on functional outcomes in patients with PT. A systematic search of the literature was performed in April 2024 on Medline and Embase. Articles involving the use of PRP in the treatment of PT were included. The risk of bias was assessed using the Risk of Bias 2 (RoB 2; the Cochrane Collaboration, England, UK) and Risk of Bias in Non-randomised Studies of Intervention (ROBINS-I; the Cochrane Collaboration, England, UK) tools. Comparative meta-analysis between the different centrifugation speeds and the different centrifugation durations was performed on articles reporting Victorian Institute of Sports Assessment - Patellar tendon (VISA-P) and visual analogue scale (VAS) scores for PT. Seventeen studies consisting of 360 participants were included in the analysis. The mean follow-up duration was 13.2 months (95% CI: 8.81 to 17.7). The mean VAS reduction was 3.85 (95% CI: -4.63 to -3.08; P < 0.01). VISA-P scores improved by 32.03 (95% CI: 24.29 to 39.78; P < 0.01). There were no significant differences between centrifuge speeds for VAS (P = 0.17) and VISA-P (P = 0.18) and between centrifuge durations for VAS (P = 0.25) and VISA-P (P = 0.27). Centrifuge speed and duration and number of centrifuge cycles did not show any significant differences in patient outcomes. There were no significant differences observed in outcomes for the different preparations of PRP. There remains a need for further high-quality RCTs using standardized PRP preparations with long-term follow-up for the development of a consensus method of PRP preparation for the treatment of PT.

Management of rotator cuff injuries using allogenic platelet-rich plasma

Rotator cuff injuries are a major cause of shoulder pain, affecting the quality of life and producing a significant burden on healthcare systems. Conservative management modalities are prioritized, resorting to surgery only when required. The field of regenerative medicine involving the use of biologics, such as platelet-rich plasma (PRP), has evolved and shown potential for managing rotator cuff injuries. Nonetheless, limitations including subpar outcomes have led clinicians to question the efficacy of autologous PRP. To circumvent this, the possibility of utilizing a standardized and well-characterized allogenic PRP for RCI has been explored. In this manuscript, we qualitatively present the evidence from in vitro, pre-clinical, clinical and ongoing studies investigating the applications of allogenic PRP in the context of rotator cuff disorders. Administration of allogenic PRP is safe and potentially efficacious to manage rotator cuff injuries, though more adequately powered randomized controlled trials with longer follow-ups are warranted to further establish the efficacy of allogenic PRP and justify its routine clinical use.

Not all platelet-rich plasma are created equal.

This review aims to elucidate potential variations in clinical outcomes resulting from the use of different types of platelet-rich plasma (PRPs) in reproductive medicine. It seeks to explore the reasons behind the diverse results reported in various studies and assess the general features distinguishing different PRP formulations. PRPs have found applications across diverse medical fields, generating controversy due to the variability in outcomes. The field of reproductive medicine, despite its limited published studies, is encountering a similar challenge as it integrates these treatments. The multitude of PRP product brands in the market, coupled with 'home-made' PRPs, poses a significant barrier to establishing a common protocol for the preparation of standardized PRP products. This impediment hinders widespread adoption by clinicians, particularly in endometrial or ovarian treatments. Drawing from evidence in other medical disciplines, this review endeavors to compile essential characteristics that PRPs must possess, aiming to mitigate the impact of variables affecting results in forthcoming studies.

Allogenic Platelet-Rich Plasma for the Treatment of Adhesive Capsulitis.

Adhesive capsulitis (AC) is a common shoulder disorder leading to pain and restricted range of motion (ROM) and affects the patient's activities of daily living (ADL) and overall quality of life (QoL). Conservative therapies are prioritized, resorting to surgical intervention only when necessary. Unfortunately, these modalities have limitations and do not address the underlying pathological cause of AC. The use of autologous biologics, such as platelet-rich plasma (PRP), has evolved and shown promise for managing musculoskeletal (MSK) injuries, including AC. However, subpar functional outcomes have led clinicians to question the long-term efficacy of autologous PRP. To circumvent this, the possibility of utilizing a standardized and well-characterized allogenic PRP for AC has been explored. In this manuscript, we qualitatively present in vitro, pre-clinical, clinical, and ongoing studies investigating the varied applications of allogenic PRP for the management of AC. The results demonstrated that allogenic PRP acts ina pleiotropic manner and decreases pro-inflammatorycytokines only in the inflammatory condition. In addition, the administration of allogenic PRP is safe and potentially efficacious, in terms of reducing pain and improving range of motion, shoulder strength, and function,in non-surgical management of AC. Nonetheless, more pre-clinical studies and adequately powered, multicenter, prospective, non-randomized, and randomized controlled trials with longer follow-up are warranted to further establish the safety and efficacy of allogenic PRP and justify its routine clinical use.

Platelet-rich plasma for jumper's knee: a comprehensive review of efficacy, protocols, and future directions.

This comprehensive review evaluates the current state of platelet-rich plasma (PRP) treatment for jumper's knee, also known as patellar tendinopathy. The aim is to assess the efficacy of PRP as a therapeutic option compared to other available procedures, investigate the benefits and potential drawbacks of PRP infiltration, and provide insights into the optimal protocols for PRP preparation and administration. A comprehensive literature search of English articles published up to June 2023 was conducted using PubMed and Scopus databases. Studies evaluating PRP for treating jumper's knee or patellar tendinopathy were analyzed to assess the current state of research in this field. PRP has demonstrated promising results in promoting cellular remodeling and accelerating the healing process in the jumper's knee. It shows potential benefits in pain reduction, improved function, and accelerated recovery. However, the efficacy of PRP varies depending on patient characteristics, disease severity, and the specific administration methodology. Establishing standardized PRP preparation and administration protocols are necessary to optimize its effectiveness. Further research is needed to define appropriate patient selection criteria and refine the application of PRP therapy in patellar tendinopathy management. Jumper's knee is commonly managed conservatively, but there is a lack of consensus on further treatment options. PRP treatment holds promise in promoting tissue healing and repair. However, standardized protocols for PRP preparation and administration, as well as optimal dosage and number of injections, require further investigation to enhance its efficacy. Continued research efforts are necessary to ascertain the precise role of PRP and its refinement in the management of patellar tendinopathy.

Process Optimization and Efficacy Assessment of Standardized PRP for Tendinopathies in Sports Medicine: Retrospective Study of Clinical Files and GMP Manufacturing Records in a Swiss University Hospital.

Platelet-rich plasma (PRP) preparations have recently become widely available in sports medicine, facilitating their use in regenerative therapy for ligament and tendon affections. Quality-oriented regulatory constraints for PRP manufacturing and available clinical experiences have underlined the critical importance of process-based standardization, a pre-requisite for sound and homogeneous clinical efficacy evaluation. This retrospective study (2013-2020) considered the standardized GMP manufacturing and sports medicine-related clinical use of autologous PRP for tendinopathies at the Lausanne University Hospital (Lausanne, Switzerland). This study included 48 patients (18-86 years of age, with a mean age of 43.4 years, and various physical activity levels), and the related PRP manufacturing records indicated a platelet concentration factor most frequently in the range of 2.0-2.5. The clinical follow-up showed that 61% of the patients reported favorable efficacy outcomes (full return to activity, with pain disappearance) following a single ultrasound-guided autologous PRP injection, whereas 36% of the patients required two PRP injections. No significant relationship was found between platelet concentration factor values in PRP preparations and clinical efficacy endpoints of the intervention. The results were in line with published reports on tendinopathy management in sports medicine, wherein the efficacy of low-concentration orthobiologic interventions appears to be unrelated to sport activity levels or to patient age and gender. Overall, this study confirmed the effectiveness of standardized autologous PRP preparations for tendinopathies in sports medicine. The results were discussed in light of the critical importance of protocol standardization for both PRP manufacturing and clinical administration to reduce biological material variability (platelet concentrations) and to enhance the robustness of clinical interventions (comparability of efficacy/patient improvement).

PRPCalc2: An App for Platelet-Rich Plasma Preparation.

Platelet-rich plasma (PRP), an inexpensive yet powerful treatment modality, is widely used but poorly understood. Three areas of unmet need are the ability to compare results using differing centrifuges and methods; translating a study result into a specific practice; and estimating yield and dosage without the benefit of an in-office hematology analyzer. PRPCalc2 is a set of software tools that facilitates these goals. The app consists of software tools that (1) calculate the appropriate radius for centrifugation, (2) calculate the correct revolutions per minute (RPM) for the centrifuge, (3) calculate the mean yield for the method and its confidence interval, and (4) calculate platelet dosage. Using these tools, a practitioner with any centrifuge can create and validate their own PRP preparation method and then use it to create a standardized PRP.

Efficacy of autologous platelet-rich plasma therapy versus topical Minoxidil in men with moderate androgenetic alopecia: a randomized open-label trial

BackgroundPlatelet-rich plasma (PRP) is an adjunctive treatment in androgenetic alopecia (AGA). Its role as a monotherapy, when compared to FDA-approved therapies in moderate grades of androgenetic alopecia is not established.ObjectivesWe sought to study the efficacy and safety of standardized non-activated PRP preparation against topical minoxidil in AGA.MethodsMen aged 20–50 with Grade III and IV (Modified Hamilton-Norwood) AGA were randomized to receive 5% Minoxidil (×6 months) or PRP injections (monthly ×3). The primary endpoints were global photographic assessment at week 24, change in target area hair counts, density, and anagen hair at week 12. Other outcomes were subjects’ satisfaction and adverse events.ResultsIn total, 64 participants were randomized. At week 24, 56% responded to Minoxidil arm and 38% to PRP (p = 0.124). There was a significant increase in target area hair count and density at week 12 within the groups. The difference between the groups was not statistically significant. Adverse events occurred in 53% and 37% of the PRP and minoxidil groups, respectively. Patient satisfaction was better with Minoxidil.ConclusionPRP is effective in the treatment of moderate grades of androgenetic alopecia in men, although perhaps not different from minoxidil. Side effects occur more frequently with PRP.

Swiss Medical Devices for Autologous Regenerative Medicine: From Innovation to Clinical Validation

Regenerative medicine, based on the use of autologous tissues and embryonic, stem or differentiated cells, is gaining growing interest. However, their preparation, in a manner compliant with good practices and health regulations, is a technical challenge. The aim of this manuscript is to present the design of reliable CE marked medical devices for the preparation of standardized platelet-rich plasma (PRP) and other autologous biologics intended for therapeutic uses. There are numerous PRP isolation processes. Depending on the methodology used, PRP composition varies greatly in terms of platelet concentration, platelet quality, and level of contamination with red and white blood cells. This variability in PRP composition might affect the clinical outcomes. The devices presented here are based on a specific technology, patented all over the world, that allows the precise separation of blood components as a function of their density using thixotropic separator gels in closed systems. This allows the preparation, in an automated manner, of leukocyte poor PRP with a standardized composition. Production of different forms of PRP is a clinical asset to suit various therapeutic needs. Therefore, we are offering solutions to prepare PRP either in liquid or gel form, and PRP combined with hyaluronic acid. These biologics have been successfully used in many different therapeutic domains, resulting in more than 150 published clinical studies. We also developed the CuteCell technology platform for cell culture expansion for further autologous cell therapies. This technology enables the safe and rapid in vitro expansion of cells intended for therapeutic use in good manufacturing practices (GMP) and autologous conditions, using blood-derived products as culture media supplementation. We summarize in this article our 20 years’ experience of research and development for the design of PRP devices and, more recently, for PRP combined with hyaluronic acid.

Clinical Response After Treatment of Knee Osteoarthritis With a Standardized, Closed-System, Low-Cost Platelet-Rich Plasma Product: 1-Year Outcomes.

Background:Intra-articular infiltration of platelet-rich plasma (PRP) is an alternative therapeutic option to classic hyaluronic acid for the treatment of symptomatic knee osteoarthritis (KOA). However, variation in preparation methods and quality assessment of PRP makes the study of its real clinical efficacy difficult.Purpose:To (1) evaluate the clinical efficacy of a characterized PRP product prepared in a standardized manner and in a closed-system for the treatment of KOA and to (2) evaluate the association of the clinical response to PRP-related variables.Study Design:Case series; Level of evidence, 4.Methods:We recruited 130 patients with nonoperative KOA and evaluated them for 1 year. PRP was prepared from a donation of autologous blood, obtaining 3 aliquots of approximately 10mL of product, which were frozen, allowing platelet disruption, platelet factor release, and long-term storage, until administration. Patients were treated 3 consecutive times every 4 weeks with an intra-articular PRP knee injection under sterile conditions. Complete blood count was performed on the whole-blood sample and the processed PRP before freezing it, for product quality assessment. Patients were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and basic satisfaction scale at 3 months, 6 months, and 1 year after intervention.Results:Quality assessment confirmed a leukocyte-poor PRP product (white blood cell count, 0.09 ± 0.09 × 109/L) with a high platelet purity (platelet count, 630.86 ± 191.75 × 109/L). WOMAC scores improved, and basic satisfaction was achieved in 70% of patients. No adverse events were reported. No correlations were observed between PRP quality parameters and clinical results. PRP complete treatment production costs were €108/US$125 (€36/US$41.6 per injection).Conclusion:This standardized PRP production method resulted in improved WOMAC scores at 1 year postoperatively in 70% of patients with KOA. This technique was safe and affordable and ensured consecutive infiltrations with the same product to each patient.

A narrative review of the research progress and clinical application of platelet-rich plasma.

As a traditional treatment invented in the 1970s, the usage of platelet-rich plasma (PRP) has been reported constantly in many medical areas, such as tissue regeneration, wound healing, ligament repair, hair loss, and so on. In this review, we focus on the administration of PRP in musculoskeletal recovery. As a part of autogenous blood plasma, PRP's platelet concentration is above the baseline. It is extracted from the host's blood sample collected before centrifugal separation. The history, mechanism and preparation of PRP, and existing clinical applications of it will become a helper for clinicians to better understand this therapy. However, the molecular mechanism of PRP treatment is still under debate. On the other hand, because of the safety concern during the PRP's preparation, the practical application of PRP is only applied in many rare cases, especially in spinal diseases. In this paper, we attempt to make a better understanding of the mechanism of PRP and the preparation of PRP; meanwhile, to raise existing questions about further application of PRP in the future. We recommend that PRP should be used in spinal diseases and other fields and in the future we ought to find a safe, simple, and standardized PRP preparation protocol.

Platelet-rich plasma for the treatment of lichen sclerosus.

Aim:Evaluate the clinical effectiveness of platelet-rich plasma as a treatment for lichen sclerosus.Methods:A systematic review was performed. The electronic databases PubMed, Ovid MEDLINE®, Web of Science, Cochrane, clinicaltrials.gov were used to identify case studies, case series, prospective uncontrolled, and randomized controlled studies published between 1946 and April 21, 2021. Six prospective uncontrolled studies, one randomized double-blind prospective study, and one case report were included.Results:Platelet-rich plasma treatment was subjectively reported to improve quality of life, but objective measures demonstrating treatment efficacy were not observed. In addition, platelet-rich plasma preparation and administration between studies lacked standardization.Conclusion:Platelet-rich plasma may be used for symptomatic adjuvant treatment of lichen sclerosus, though additional double-blind controlled studies with standardized platelet-rich plasma protocols are needed to better characterize the efficacy of platelet-rich plasma.

Assessment of Quality of Platelet-Rich Plasma Produced With Desktop Centrifuge and Comparison With Standardized Commercially Available Platelet-rich plasma.

ABSTRACTAims:The aim of this study was to assess the quality of platelet-rich plasma (PRP) produced by in-house desktop centrifuge method and compare it with that of standardized commercial PRP.Materials and Methods:REMI desktop centrifuge was used to prepare PRP and to compare with standardized commercial PRP by calculating the quantity of platelets using Beckman Coulter cell counter in 10 PRP samples and assessing the morphological quality of platelets using JEOL JEM transmission electron microscope (TEM).Statistical Analysis Used:The t test for platelet count in desktop PRP with the test value of therapeutic PRP was 12.618. The P value was <0.001, which was significant statistically. The data followed a normal distribution in normal Q-Q plot for platelet count in desktop centrifuge. So the test samples were not much deviated.Results:The platelet count was lesser than that of standardized commercial PRP. When viewed under JEOL JEM transmission electron microscope, the α granules in platelets were intact and the morphological quality of the PRP was good.Conclusions:With this study, we have determined that the morphological quality of PRP produced by the in-house desktop centrifuge method is comparable to that of standardized commercial PRP. Though the quantity of platelets was less than 1 million cells/μL, the clinical results were good with desired bone formation, thereby providing good avenue for further research.

Platelet-Rich Plasma and Osteoarthritis of the Knee: A Literature Review

Osteoarthritis (OA) is a debilitating disease affecting people worldwide that affects weight-bearing joints, including the knee. Pharmacological options should be attempted before surgical therapy, especially for the younger population where there is a likelihood of residual symptoms and risk of revision post-surgery. There are several injection therapies available to treat symptoms and slow degenerative process. One option is platelet-rich plasma (PRP).The study aims to answer the following questions: What effect does PRP have on osteoarthritic chondrocytes?What are the current results on the clinical outcomes of PRP on knee OA?A search was conducted on Google Scholar and PubMed to find studies from the past five years on “knee osteoarthritis” and ”platelet-rich plasma”.Results from current findings demonstrate that PRP induces chondroprotection in vitro. Clinically, PRP improves short-term outcomes of symptomatic knee OA. Although the results look promising; unfortunately, a standardized PRP protocol has not been established and several studies are biased, thus the efficacy of PRP is still inconclusive.

Anti-Inflammatory Effects of Novel Standardized Platelet Rich Plasma Releasates on Knee Osteoarthritic Chondrocytes and Cartilage in vitro.

Platelet Rich Plasma (PRP) has recently emerged as a potential treatment for osteoarthritis (OA), but composition heterogeneity hampers comparison among studies, with the result that definite conclusions on its efficacy have not been reached. 1) To develop a novel methodology to prepare a series of standardized PRP releasates (PRP-Rs) with known absolute platelet concentrations, and 2) To evaluate the influence of this standardization parameter on the anti-inflammatory properties of these PRP-Rs in an in vitro and an ex vivo model of OA. A series of PRPs was prepared using the absolute platelet concentration as the standardization parameter. Doses of platelets ranged from 0% (platelet poor plasma, PPP) to 1.5·105 platelets/µl. PRPs were then activated with CaCl2 to obtain releasates (PRP-R). Chondrocytes were stimulated with 10% of each PRP-R in serum-free culture medium for 72 h to assess proliferation and viability. Cells were co-stimulated with interleukin (IL)-1β (5 ng/ml) and 10% of each PRP-R for 48 h to determine the effects on gene expression, secretion and intra-cellular content of common markers associated with inflammation, catabolism and oxidative stress in OA. OA cartilage explants were co-stimulated with IL-1β (5 ng/ml) and 10% of either PRP-R with 0.75·105 platelets/µl or PRP-R with 1.5·105 platelets/µl for 21 days to assess matrix inflammatory degradation. Chondrocyte viability was not affected, and proliferation was dose-dependently increased. The gene expression of all pro-inflammatory mediators was significantly and dose-independently reduced, except for that of IL-1β and IL-8. Immunoblotting corroborated this effect for inducible NO synthase (NOS2). Secreted matrix metalloproteinase-13 (MMP-13) was reduced to almost basal levels by the PRP-R from PPP. Increasing platelet dosage led to progressive loss to this anti-catabolic ability. Safranin O and toluidine blue stains supported the beneficial effect of low platelet dosage on cartilage matrix preservation. We have developed a methodology to prepare PRP releasates using the absolute platelet concentration as the standardization parameter. Using this approach, the composition of the resulting PRP derived product is independent of the donor initial basal platelet count, thereby allowing the evaluation of its effects objectively and reproducibly. In our OA models, PRP-Rs showed antiinflammatory, anti-oxidant and anti-catabolic properties. Platelet enrichment could favor chondrocyte proliferation but is not necessary for the above effects and could even be counter-productive.

Application of standardized platelet-rich plasma in elderly patients with complex wounds.

In recent years, autologous platelet-rich plasma (PRP) derivatives have been used widely in the regeneration and repair of tissue, but a standard definition and preparation method for PRP are lacking. We developed a standardized method using platelet indices as quality-control indicators for PRP preparation. Twenty-one elderly patients (9 males, 12 females) with complex wounds were treated with standardized platelet-rich plasma (S-PRP). The platelet count in PRP after the second centrifugation was 1,069-1,436 × 109 /L. We adjusted the platelet concentration in PRP after a second centrifugation to 1,000 × 109 /L according to a formula using platelet-poor plasma (PPP). The standardized preparation method that we developed gave S-PRP with a relatively uniform platelet concentration. The wounds of 21 patients showed accelerated healing after S-PRP treatment, and there were no obvious side effects during treatment. These data suggest that our preparation method of S-PRP, using platelet indices as quality-control indicators with platelet count of 1,000 × 109 /L could be used for the treatment of complex wounds in the elderly. The preparation method of S-PRP proposed in the present study may be a simple and effective method of PRP quality control.

Preparation, Procedures and Evaluation of Platelet-Rich Plasma Injection in the Treatment of Knee Osteoarthritis.

Knee osteoarthritis (KOA) is one of the most frequently encountered diseases in the orthopedic department. Existing non-surgical treatments have a limited effect on the repair of cartilage and on bone regeneration. Platelet-rich plasma (PRP) is an autologous bioactive substance that can repair cartilage injury and accelerate bone regeneration effectively. However, reporting of PRP preparation protocols in clinical studies is highly inconsistent, with the majority of studies providing insufficient information to allow the protocol to be reproduced. We describe a repeatable method of preparing PRP visually, the treatment of KOA using PRP intra-articular injection, and methods of evaluating the outcome. PRP was prepared using manual double centrifugation. The PRP layer was extracted from peripheral blood and used for knee joint cavity injection. Evaluations included assessments of blood platelet concentrations and clinical outcomes. Preparation of PRP by manual centrifugation requires less apparatus and is less costly than plasma filtration or centrifugation using equipment. The centrifugation time of our double centrifugation method was 6 and 5 minutes for the respective centrifugations at forces of 800 and 1400 x g, respectively, to allow for the consistent preparation of standardized PRP. However, a manual method is susceptible to operator error, and PRP batch preparation is not available. Intra-articular injection of PRP proved to be an effective treatment for knee osteoarthritis. The entire treatment procedure took less than 30 minutes, the blood platelet concentration of PRP could be standardized, and treatment was proven to be effective when evaluated by follow-up.

Platelet-rich plasma and the shoulder: clinical indications and outcomes.

The orthopedic community has seen a rapid rise in the clinical use of platelet-rich plasma (PRP) in the management of shoulder pathologies over the past decade. The purpose of this paper is to review the current literature regarding the indications and outcomes of PRP for the surgical and non-surgical management of common shoulder pathologies, including rotator cuff tears. Multiple studies have been published recently regarding the use of PRP for the operative and non-operative treatment of rotator cuff tears. There has been less research published on the use of PRP in the management of other conditions of the shoulder. Despite attempts to standardize and classify PRP formulations, there remains great variation in the inter- and intra-subjection composition, preparation, and administration techniques of PRP, limiting the conclusions that can be drawn regarding the utility and effectiveness of this biologic treatment as reported by Mazzocca et al. (J Bone Joint Surg Am. 94(4):308-16, 2012). Recent literature has shown equivocal to minor benefit of PRP use for shoulder pain, function, and healing. While few complications have been reported and PRP administration appears to carry little risk to the patient, the body of literature is currently inconclusive regarding the clinical benefit and cost-effectiveness of PRP in the treatment of shoulder pathology. As for PRP use specifically as an adjunct to surgical rotator cuff repairs, there is no clear consensus on its effectiveness in either clinical or structural outcomes. To further delineate the efficacy of PRP for shoulder pathology, it is essential that more double-blinded, randomized controlled investigations with large sample sizes and standardized PRP preparations be performed.

Platelet-Rich Plasma Modulates Actions on Articular Cartilage Lubrication and Regeneration.

Osteoarthritis (OA) is characterized by articular cartilage degeneration in the joints and results in pain, swelling, stiffness, muscle atrophy, and attendant functional disability. The progression of OA cannot be prevented by drugs. Current treatments for OA focus on symptomatic relief of pain. Recently, platelet-rich plasma (PRP) injection has attracted much attention for modulating articular cartilage and synovial membrane in OA. Despite the increasing interest in PRP for the treatment of OA, the precise mechanisms underlying the actions of PRP on OA remain unclear. We have reviewed the known actions of PRP in the joint. The in vitro and in vivo evidence is reviewed concerning the potential of the modulation of PRP on normal articular cartilage and OA progression. PRP modulates the repair and regeneration of damaged articular cartilage in the joints and delays the degeneration of cartilage by stimulation of mesenchymal stem cell migration, proliferation, and differentiation into articular chondrocytes. In addition to the symptomatic relief, PRP is a biological response modifier of inflammatory nuclear factor-κB signaling pathway and PRP reduces the pain by decreasing inflammation and angiogenesis of the synovial membrane where pain receptors are localized. PRP has the therapeutic potential not only to promote tissue regeneration, but also to contribute to articular cartilage lubrication by decreasing the friction coefficient and minimizing wear. Although further refinements and improvements are needed in standardized PRP preparations, PRP may modulate regeneration of articular cartilage and retards the progression of OA by stimulating cell migration, proliferation, differentiation of progenitor/stem cells, joint homeostasis, and joint lubrication.

Platelet-Rich Plasma Preparation Types Show Impact on Chondrogenic Differentiation, Migration, and Proliferation of Human Subchondral Mesenchymal Progenitor Cells

To evaluate the chondrogenic potential of platelet concentrates on human subchondral mesenchymal progenitor cells (MPCs) as assessed by histomorphometric analysis of proteoglycans and type II collagen. Furthermore, the migratory and proliferative effect of platelet concentrates were assessed. Platelet-rich plasma (PRP) was prepared using preparation kits (Autologous Conditioned Plasma [ACP] Kit [Arthrex, Naples, FL]; Regen ACR-C Kit [Regen Lab, Le Mont-Sur-Lausanne, Switzerland]; and Dr.PRP Kit [Rmedica, Seoul, Republic of Korea]) by apheresis (PRP-A) and by centrifugation (PRP-C). In contrast to clinical application, freeze-and-thaw cycles were subsequently performed to activate platelets and to prevent medium coagulation by residual fibrinogen invitro. MPCs were harvested from the cortico-spongious bone of femoral heads. Chondrogenic differentiation of MPCs was induced in high-density pellet cultures and evaluated by histochemical staining of typical cartilage matrix components. Migration of MPCs was assessed using a chemotaxis assay, and proliferation activity was measured by DNA content. MPCs cultured in the presence of 5% ACP, Regen, or Dr.PRP formed fibrous tissue, whereas MPCs stimulated with 5% PRP-A or PRP-C developed compact and dense cartilaginous tissue rich in type II collagen and proteoglycans. All platelet concentrates significantly (ACP, P= .00041; Regen, P= .00029; Dr.PRP, P= .00051; PRP-A, P < .0001; and PRP-C, P < .0001) stimulated migration of MPCs. All platelet concentrates but one (Dr.PRP, P= .63) showed a proliferative effect on MPCs, as shown by significant increases (ACP, P= .027; Regen, P= .0029; PRP-A, P= .00021; and PRP-C, P= .00069) in DNA content. Platelet concentrates obtained by different preparation methods exhibit different potentials to stimulate chondrogenic differentiation, migration, and proliferation of MPCs. Platelet concentrates obtained by commercially available preparation kits failed to induce chondrogenic differentiation of MPCs, whereas highly standardized PRP preparations did induce such differentiation. These findings suggest differing outcomes with PRP treatment in stem cell-based cartilage repair. Our findings may help to explain the variability of results in studies examining the use of PRP clinically.