Leukocyte-poor Platelet-rich Plasma Research Articles

Platelet-rich plasma promotes recruitment of macrophages in the process of tendon healing.

IntroductionResearchers have investigated the use of platelet-rich plasma (PRP) therapy. However, the mechanisms through which PRP affects tissue repair remain unclear. We hypothesize that PRP promotes tissue repair through not only via direct manner on the local cells but also via indirect manner that encourage the recruitment of reparative cells such as macrophages (MPs), and it depends on the quality of PRP including the concentration of leukocytes. The aim of this study is to elucidate the actions of the MPs in the mechanisms of PRP on tissue repair processes.MethodsLeukocyte-rich (LR) PRP and leukocyte-poor (LP) PRP were prepared from 12-week-old C57BL6 mice. Full-thickness defects were created in central third of patellar tendons of 12-week-old C57BL/6 mice for histologic analysis (n = 36) and 12-week-old B6.129P-Cx3cr1tm1Litt/J mice for flow cytometry analysis (n = 108). B6.129P-Cx3cr1tm1Litt/J mouse is GFP-positive only in the MP-linage cells thus MPs recruited to the repair tissue can be distinguished whether it had originated from administrated PRP or recruited from host mouse. Mice were treated either with LR-PRP, LP-PRP, or without PRP (control group). Histological analyses were performed to evaluate the tendon healing using Bonar score as semi-quantitative histological scoring system. Flow cytometric analyses were performed to count the number of GFP-positive cells around repaired patellar tendon. In addition, the ratio of pro-inflammatory MPs (M1)/anti-inflammatory MPs (M2) were analyzed in those GFP-positive cells. The statistical analysis was performed using GraphPad Prism ver6. P values < 0.05 were considered statistically significant.ResultsIn LR-PRP and LP-PRP groups, all variables in Bonar score such as cell morphology, cellularity, vascularity, and collagen arrangement were significantly improved in comparison with control group, indicating that both PRPs promote tendon hearing. LP-PRP promoted the tendon healing significantly faster than that of LR-PRP on postoperative day 28 (P < 0.001). LR-PRP enhanced angiogenesis (vascularity: P < 0.001), while LP-PRP improved the collagen arrangement on postoperative day 28 (collagen arrangement: P < 0.01). In other variables such as cell morphology and cellularity score, there were no significant differences between LR-PRP and LP-PRP groups in any time points. Flow cytometric findings showed that recruitment of GFP-positive MPs in the LR and LP-PRP groups were significantly increased from postoperative day 4 compared with control group without PRP treatment (P < 0.001). The majority of GFP-positive MPs were M1 at the initiation of tendon healing phase, and M2 were gradually increased from postoperative day 4. The number of M1 was significantly high both in the LP- and LR-PRP groups (day 4 and 7, p < 0.001), but the number of M2 was high only in the LP-PRP group (day 7 and 14, P < 0.05) when it compared with control group. The M1/M2 ratio on postoperative day 7 was significantly lower in the LP-PRP group than those in the control group (P < 0.05).ConclusionsThis study demonstrated that PRP enhanced the tendon healing and promoted the recruitment of MPs to the injured tissue. The subtypes of MPs were different depends on the types of PRPs, suggesting that leukocytes in PRP influence the effect of PRP therapy.

Platelet-Rich Plasma Versus Hyaluronic Acid for Knee Osteoarthritis: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background: Platelet-rich plasma (PRP) and hyaluronic acid (HA) are 2 nonoperative treatment options for knee osteoarthritis (OA) that are supposed to provide symptomatic relief and help delay surgical intervention. Purpose: To systematically review the literature to compare the efficacy and safety of PRP and HA injections for the treatment of knee OA. Study Design: Meta-analysis of level 1 studies. Methods: A systematic review was performed by searching PubMed, the Cochrane Library, and Embase to identify level 1 studies that compared the clinical efficacy of PRP and HA injections for knee OA. The search phrase used was platelet-rich plasma hyaluronic acid knee osteoarthritis randomized. Patients were assessed via the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analog scale (VAS) for pain, and Subjective International Knee Documentation Committee (IKDC) scale. A subanalysis was also performed to isolate results from patients who received leukocyte-poor and leukocyte-rich PRP. Results: A total of 18 studies (all level 1) met inclusion criteria, including 811 patients undergoing intra-articular injection with PRP (mean age, 57.6 years) and 797 patients with HA (mean age, 59.3 years). The mean follow-up was 11.1 months for both groups. Mean improvement was significantly higher in the PRP group (44.7%) than the HA group (12.6%) for WOMAC total scores (P < .01). Of 11 studies based on the VAS, 6 reported PRP patients to have significantly less pain at latest follow-up when compared with HA patients (P < .05). Of 6 studies based on the Subjective IKDC outcome score, 3 reported PRP patients to have significantly better scores at latest follow-up when compared with HA patients (P < .05). Finally, leukocyte-poor PRP was associated with significantly better Subjective IKDC scores versus leukocyte-rich PRP (P < .05). Conclusion: Patients undergoing treatment for knee OA with PRP can be expected to experience improved clinical outcomes when compared with HA. Additionally, leukocyte-poor PRP may be a superior line of treatment for knee OA over leukocyte-rich PRP, although further studies are needed that directly compare leukocyte content in PRP injections for treatment of knee OA.

Comparison of Leukocyte-Rich Platelet-Rich Plasma and Leukocyte-Poor Platelet-Rich Plasma on Achilles Tendinopathy at an Early Stage in a Rabbit Model

Background: Tendinopathy is still a great challenge in clinical practice, and the role of platelet-rich plasma (PRP) is controversial. The influence of leukocytes on tendinopathy at an early stage has not been defined so far. Purpose: To compare the effects of leukocyte-rich PRP (Lr-PRP) and leukocyte-poor PRP (Lp-PRP) on Achilles tendinopathy when applied at an early stage. Study Design: Controlled laboratory study. Methods: A rabbit Achilles tendinopathy model was induced by a collagenase injection. A week later, treatments were applied randomly on local Achilles tendon lesions: (1) 200 μL of Lr-PRP (16 legs), (2) 200 μL of Lp-PRP (16 legs), and (3) 200 μL of saline (16 legs). At 3 and 6 weeks after the collagenase injection, outcomes were evaluated by histology, magnetic resonance imaging (MRI), real-time polymerase chain reaction analysis, immunohistochemistry, and transmission electron microscopy (TEM). Results: The Lr-PRP group had a lower T2 signal intensity (P = .0377) and smaller diameter (P = .0193) and cross-sectional area (P = .0194) than the Lp-PRP group on MRI. Histologically, the Lr-PRP group had better scores than the Lp-PRP group (P = .0284 and P = .0188, respectively). Compared with the Lp-PRP group, higher gene expression and more protein synthesis of collagen I (P = .0160 and P = .0309, respectively) and CD163 (P < .0001 and P = .0411, respectively) were found in the Lr-PRP group. Considering TEM and biomechanical testing, the Lr-PRP group demonstrated more mature collagen fibers (P < .0001), a larger fiber diameter (P = .0005), a higher failure load (P = .00417), and higher tensile stress (P < .0001) than the Lp-PRP group. Conclusion: Lr-PRP had more beneficial effects than Lp-PRP when delivered at an early stage during tendon repair. Clinical Relevance: Here, we showed that tendinopathy influenced the curative effects of PRP in vivo. An early-stage application of Lr-PRP had more benefits for the repair of tendinopathy than Lp-PRP in a rabbit model, which will supplement guidelines of PRP treatment on tendinopathy clinically.

Comparison of two platelet rich plasma formulations with viscosupplementation in treatment of moderate grade gonarthrosis: A prospective randomized controlled study

BackgroundThe success of platelet rich plasma (PRP) applications in conservative treatment of moderate gonarthrosis has increased over time. Two different PRP formulations that buffy coat (Leukocyte rich PRP: LR-PRP) and plasma-based (Leukocyte poor PRP: LP-PRP) are obtained by different centrifugation methods. This prospective randomized trial was whether LP-PRP will be more effective combination for moderate gonarthrosis when compared to LR-PRP or HA. MethodsA total 90 patients suffering from moderate knee osteoarthritis were enrolled. Patients were divided equally into three groups and treated with 3 times LR-PRP, LP-PRP and HA injections. A prospective evaluation was done at baseline, and then at 2, 6 and 12 months of follow-up using VAS, WOMAC and Likert scoring systems. ResultsThe 2nd, 6th and 12th month VAS and WOMAC scores of LR-PRP demonstrated the most obvious improvement. Recurrence of symptoms was statistically lower (3; 10%) in LR-PRP group (p < 0.001). Male gender had lower recurrence rate than females (1 vs. 18; p = 0.043). Only high BMI had statistically negative effect on recovery and recurrence rates (p = 0.004). Local adverse effects were more common in LR-PRP group (p < 0.05). ConclusionsPRP injections produced superior results than HA. LR-PRP seems to be the most effective treatment modality for moderate gonarthrosis especially in normal weighted men at the 6th decade of age.

Quality comparison between two different types of platelet-rich plasma for knee osteoarthritis.

Introduction: Knee osteoarthritis (KOA), the most common form of osteoarthritis (OA) is a considerable health concern worldwide. Platelet-rich plasma (PRP) is a common therapeutic option for KOA. Different types of PRPs have varying efficacies. However, a comparative analysis of the qualities of these PRPs is lacking. Methods: Two types of PRPs, including autologous protein solution (APS), and leukocyte-poor PRP (LP-PRP) along with whole blood (WB) and platelet-poor plasma (PPP) were characterized for platelet content, leukocyte content, and composition in 10 healthy volunteers (HV) (the controlled laboratory study) and 16 KOA patients (a retrospective observational study). Additionally, the levels of the platelet-derived growth factor (PDGF)-BB, and different cytokines were estimated in HV. Results: In HV, the concentrations of platelets and leukocytes, levels of different cytokines, including interleukin 1 receptor antagonist (IL-1Ra), soluble TNF receptor type II (sTNF-RII), and IL-1β, and the ratio of IL-1Ra/IL-1β were significantly higher in APS, whereas the PDGF-BB was higher in LP-PRP than APS. In KOA patients, a higher concentration of platelets was observed in LP-PRP, and a higher concentration of leukocytes was observed in APS than LP-PRP. Following the PAW classification system, LP-PRP was classified as P2-B type in HV (51.3 × 104/μl) and KOA (53.4 × 104/μl), whereas APS was classified as P3-A type in HV (110.1 × 104/μl) and P2-A type in KOA (29.0 × 104/μl). In a retrospective observational study, the KOA patients who underwent APS injection had a higher incidence of arthralgia, and this arthralgia lasted for a longer time than LP-PRP injection in the same individual. Discussion: The quality of the two PRPs differed distinctively depending on their preparation methods, which might affect their clinical efficacies and adverse events. Therefore, the characterization of these parameters should be prioritized while choosing PRP.

Optimal double-spin method for maximizing the concentration of platelets in equine platelet-rich plasma.

ABSTRACTThis study optimized the double-spin conditions for preparing equine platelet-rich plasma (PRP): leukocyte-rich PRP (L-PRP) and leukocyte-poor PRP (P-PRP). Whole blood samples were centrifuged at various double-spin conditions. Both L-PRP and P-PRP were prepared at each stage, and complete blood counts and growth factor concentrations were compared. Samples centrifuged at 160 × 900 g, 160 × 2,000 g, and 400 × 2,000 g exhibited the highest platelet counts. P-PRP had significantly lower leukocyte and erythrocyte contents than L-PRP, especially at 400 × 2,000 g. No significant differences were observed in growth factor concentrations. Our data suggest that optimum L-PRP preparation should include centrifugation under the aforementioned conditions, whereas centrifugation at 400 × 2,000 g is optimal for P-PRP.

Use of Fresh Leukocyte-rich Platelet Rich Plasma or Fresh Leukocyte-poor Platelet Rich Plasma for the Treatment of Knee Cartilage Degeneration: a Randomized Controlled Trial

Use of Fresh Leukocyte-rich Platelet Rich Plasma or Fresh Leukocyte-poor Platelet Rich Plasma for the Treatment of Knee Cartilage Degeneration: a Randomized Controlled Trial

Autologous bone marrow expanded mesenchymal stem cells in patellar tendinopathy: protocol for a phase I/II, single-centre, randomized with active control PRP, double-blinded clinical trial

IntroductionPatellar tendon overuse injuries are common in athletes. Imaging may show a change in tissue structure with tendon thickening and disruption of the intratendinous substance. We wish to test the hypothesis that both autologous bone marrow expanded mesenchymal stem cells and autologous leukocyte-poor platelet-rich plasma (LP-PRP) implanted into the area of the disrupted tendinopathic patellar tendon will restore function, but tendon regeneration tissue will only be observed in the subjects treated with autologous bone marrow expanded mesenchymal stem cells.Methods and analysisThis is a single-centre, pilot phase I/II, double-blinded clinical trial with randomisation with active control. Twenty patients with a diagnosis of patellar tendinopathy with imaging changes (tendon thickening and disruption of the intratendinous substance at the proximal portion of the patellar tendon) will be randomised in a 1:1 ratio to receive a local injection of either bone-marrow autologous mesenchymal stem cells (MSC), isolated and cultured under GMP at The Institute of Biology and Molecular Genetics (IBGM) (Spain) or P-PRP. The study will have two aims: first, to ascertain whether a clinically relevant improvement after 3, 6 and 12 months according to the visual analogue scale (VAS), Victorian Institute of Sport Assessment for patellar tendons (VISA-P) and dynamometry scales (DYN) will be achieved; and second, to ascertain whether the proposed intervention will restore tendon structure as determined by ultrasonography (US), Doppler ultrasonography (DUS), and innovative MRI and ultrasound techniques: Magnetic Resonance T2 FAT SAT (UTE, Ultrashort Echo TE) sequence and Ultrasound Tissue Characterization (UTC). Patients who are randomised to the P-PRP treatment group but do not achieve a satisfactory primary endpoint after 6 months will be offered treatment with MSC.Trial registrationNCT03454737.

Use of Platelet-Rich Plasma for the Improvement of Pain and Function in Rotator Cuff Tears: A Systematic Review and Meta-analysis With Bias Assessment

Background: Many clinical trials have investigated the use of platelet-rich plasma (PRP) to treat rotator cuff–related abnormalities. Several meta-analyses have been published, but none have focused exclusively on level 1 randomized controlled trials. Purpose: To assess the efficacy of PRP for rotator cuff–related abnormalities and evaluate how specific tendon involvement, the inclusion of leukocytes, and the use of gel/nongel formulations affect pain and functional outcomes. Study Design: Systematic review and meta-analysis. Methods: The literature was screened following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Baseline, short-term, and long-term data were extracted for the Constant score, University of California, Los Angeles (UCLA) score, visual analog scale (VAS) for pain, retear rate, Simple Shoulder Test (SST), and American Shoulder and Elbow Surgeons (ASES) score. The 100-point modified Coleman Methodology Score (CMS) was used to assess methodological quality. Funnel plots and the Egger test were used to screen for publication bias, and sensitivity analysis was performed to evaluate the effect of potential outliers. Results: A total of 18 level 1 studies were included in this review, 17 (1116 patients) of which could be included in quantitative analysis. The mean modified CMS was 79.4 ± 10.39. The Constant scores of patients who received PRP were significantly better short term (weighted mean difference [WMD], 2.89 [95% CI, 0.89-4.90]; P < .01) and long term (WMD, 2.66 [95% CI, 1.13-4.19]; P < .01). The VAS scores were significantly improved short term (WMD, –0.45 [95% CI, –0.75 to −0.15]; P < .01). Sugaya grade IV and V retears in PRP-treated patients were significantly reduced long term (odds ratio [OR], 0.34 [95% CI, 0.20-0.57]; P < .01). In PRP-treated patients with multiple tendons torn, there were reduced odds of retears (OR, 0.28 [95% CI, 0.13-0.60]; P < .01). Patients who received leukocyte-rich PRP had significantly better Constant scores compared with the leukocyte-poor PRP group, but there was no difference in VAS scores. Patients receiving PRP gel reported higher Constant scores compared with the controls, whereas those receiving nongel PRP treatments did not, although there was no difference in VAS scores. Long-term odds of retears were decreased, regardless of leukocyte content (leukocyte-poor PRP: OR, 0.36 [95% CI, 0.16-0.82]; leukocyte-rich PRP: OR, 0.32 [95% CI, 0.16-0.65]; all P < .05) or usage of gel (nongel: OR, 0.42 [95% CI, 0.23-0.76]; gel: OR, 0.17 [95% CI, 0.05-0.51]; all P < .01). Conclusion: Long-term retear rates were significantly decreased in patients with rotator cuff–related abnormalities who received PRP. Significant improvements in PRP-treated patients were noted for multiple functional outcomes, but none reached their respective minimal clinically important differences. Overall, our results suggest that PRP may positively affect clinical outcomes, but limited data, study heterogeneity, and poor methodological quality hinder firm conclusions.

Platelet-rich plasma (PRP) for patellar tendinopathy: a randomized controlled trial of leukocyte-rich PRP or leukocyte-poor PRP vs. saline

Background: A small number of randomized controlled trials have found ultrasound-guided injection of PRP to be no more effective than saline for several tendinopathies; limited information exists for patellar tendinopathy. The purpose of this study was to determine if a single ultrasound-guided PRP injection, either leukocyte-rich (LR–PRP) or leukocyte-poor (LP–PRP), was superior to saline injection, for the treatment of patellar tendinopathy. Our null hypothesis was that no treatment would be superior to another for the treatment of patellar tendinopathy.

Platelet yield and yield consistency for six single-spin methods of platelet rich plasma preparation

Single-spin methods of preparation of platelet-rich plasma are used widely in private practice, yet they have not been extensively studied and compared. The use of platelet-rich plasma (PRP) by the private practitioner can be facilitated by efficient and predictable PRP preparation. The primary purpose of this study was to study common methods of single-spin PRP preparation to determine their efficiency and variability. Six single-spin methods of PRP production from whole blood were analyzed. The primary measures were mean yield and standard deviation as the quotient of total platelet count in PRP produced divided by total platelet count in whole blood utilized. Each sample was analyzed in triplicate and the results were averaged. Secondary measures included red blood cell count (RBC) and white blood cell count (WBC), concentration ratio, and variable cost per million platelets produced. Sixty-four volunteers provided samples from 30 June 2017 to 30 September 2018. Seventeen to twenty six samples were utilized to assess each method. Yields for the six preparation methods (PMs) varied from 53(±18)% to 72(±13)%. Differences were observed for WBC count (1.8 to 14), Hematocrit (0.8 to 32), platelet concentration (568 to 1062), and variable cost per billion platelets produced ($1.55 to $44.31). All six methods evaluated provided a platelet yield of more than 50%, although two methods were less efficient than the others. Two methods were able to produce leukocyte-poor PRP. Variability was moderate across all methods, suggesting that estimation of platelet yield should be feasible from a baseline platelet count for all methods.

Effect of Combined Leukocyte-Poor Platelet-Rich Plasma and Hyaluronic Acid on Bone Marrow-Derived Mesenchymal Stem Cell and Chondrocyte Metabolism.

Given the potential applications of combined biologics, the authors sought to evaluate the in vitro effect of combined platelet-rich plasma (PRP) and hyaluronic acid (HA) on cellular metabolism. Bone marrow-derived mesenchymal stem cells (BMSCs) and chondrocytes were obtained from the femurs of Sprague-Dawley rats. An inflammatory model was created by adding 10 ng/mL interleukin-1-beta to culture media. Non-crosslinked high-molecular-weight HA, activated-PRP (aPRP), and unactivated-PRP (uPRP) were tested. Cellular proliferation and gene expression were measured at 1 week. Genes of interest included aggrecan, matrix metalloproteinase (MMP)-9, and MMP-13. Combined uPRP-HA was associated with a significant increase in chondrocyte and BMSC proliferation at numerous preparations. There was a trend of increased chondrocyte aggrecan expression with combined PRP-HA. The greatest and only significant decrease in BMSC MMP-9 expression was observed with combined PRP-HA. While a significant reduction of BMSC MMP-13 expression was seen with PRP and HA-alone, a greater reduction was observed with PRP-HA. MMP-9 chondrocyte expression was significantly reduced in cells treated with PRP-HA. PRP-alone and HA-alone at identical concentrations did not result in a significant reduction. The greatest reduction of MMP-13 chondrocyte expression was observed in chondrocytes plus combined PRP-HA. We demonstrated a statistically significant increase in BMSC and chondrocyte proliferation and decreased expression of catabolic enzymes with combined PRP-HA. These results demonstrate the additive in vitro effect of combined PRP-HA to stimulate cellular growth, restore components of the articular extracellular matrix, and reduce inflammation.

Optimization of leukocyte-poor platelet-rich plasma preparation: a validation study of leukocyte-poor platelet-rich plasma obtained using different preparer, storage, and activation methods

BackgroundAlternative methods of platelet-rich plasma (PRP) preparation, storage, and activation that can be stably reproduced are needed to improve PRP production. The purpose of this study was to investigate the effect of the preparer’s experience on the quality of prepared PRP, chronological changes occurring in PRP, and the effect of the activation procedures on the release of several growth factors from PRP, using PRP prepared with the PRGF-Endoret Kit.MethodsLeukocyte-poor PRP samples from seventeen healthy volunteers were prepared using the PRGF-Endoret Kit and the PRGF IV System Centrifuge. The platelet and leukocyte concentrations were compared based on the preparer’s experience. The concentrations of platelets, hepatocyte growth factor (HGF), platelet-derived growth factor-BB (PDGF-BB), and insulin-like growth factor-1 (IGF-1) were determined at 0 and 60 min after PRP preparation, and compared. Concentrations of the above growth factors from PRP activated by freeze–thaw cycling and by calcium chloride (CaCl2) were also compared.ResultsNo significant difference was observed in the platelet concentrations and leukocyte contamination rates, based on the preparer’s experience. At 60 min after PRP preparation, the platelet concentration decreased significantly, while the HGF, PDGF-BB, and IGF-1 concentrations remained unchanged. Activation with CaCl2 resulted in a significant increase in the PDGF-BB levels, although the HGF and IGF-1 concentrations remained unchanged.ConclusionsThe results of this study show that leukocyte-poor PRP prepared using the PRGF-Endoret Kit did not result in any qualitative difference that depended on the experience of the preparer. However, PRP preparation required standardization in terms of the time of blood count measurement. Growth factor concentrations in PRP differed according to the platelet-activation method used.

Prospective Clinical Research of the Efficacy of Platelet-rich Plasma in the Outpatient-based Treatment of Rotator Cuff Tendinopathy.

BackgroundThe purpose of this study is to compare the clinical outcomes of the control group and platelet-rich plasma (PRP) group among the patients who failed to respond to conservative treatment as outpatient-based therapy for rotator cuff tendinopathy, and to compare the clinical results of leukocyte-poor (LP) PRP and leukocyte-rich (LR) PRP.MethodsInclusion criteria are (1) over 18-year-old, (2) patients with rotator cuff tendinopathy, no rotator cuff tear by radiologic diagnosis (ultrasonography or magnetic resonance imaging) within the last 3 months, and (3) not effective to conservative treatment for more than 1 month. Of the final 60 subjects, 33 patients in the exercise treatment group and 27 patients in the PRP injection group (LP-PRP, 13; LR-PRP, 14) were included. Clinical evaluation was carried out by assessing the outcomes of treatment using the Numeric Rating Scale pain score, the American Shoulder and Elbow Society (ASES) score, and the Constant score at baseline and at 3 and 6 months after the procedure.ResultsThere was a statistically significant difference in ΔASES3months (ASES3months-ASESfirst) score between the control and PRP groups (p=0.006). However, there was no statistical significance between LP-PRP and LR-PRP groups (p>0.05).ConclusionsThis study showed that PRP injection was more effective than exercise therapy for the first 3 months. However, there was no difference between the LP-PRP group and the LR-PRP group. Regardless of the type of PRP, clinical application of PRP injection in patients with rotator cuff tendinopathy seems to be effective in early treatment.

Platelet-Rich Plasma for Patellar Tendinopathy: A Randomized Controlled Trial of Leukocyte-Rich PRP or Leukocyte-Poor PRP Versus Saline

Background: A small number of randomized controlled trials have found ultrasound-guided injection of platelet-rich plasma (PRP) to be no more effective than saline for several tendinopathies; limited information exists for patellar tendinopathy. In addition, different PRP formulations that produce varying concentrations of leukocytes have not been directly compared for patellar tendinopathy. Purpose/Hypothesis: To determine if a single ultrasound-guided PRP injection, either leukocyte-rich PRP (LR-PRP) or leukocyte-poor PRP (LP-PRP), was superior to saline injection for the treatment of patellar tendinopathy. The null hypothesis was that no treatment would be superior to another for the treatment of patellar tendinopathy. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: Athletes with patellar tendinopathy for ≥6 months (Blazina stage IIIB) were assessed for eligibility in a multisite single-blind controlled trial. There were 3 injection arms: LR-PRP, LP-PRP, and saline. Patients received a single ultrasound-guided injection, followed by 6 weeks of supervised rehabilitation (heavy slow resistance training, concentric and eccentric, 3 times per week). Outcome measures—Victorian Institute of Sport Assessment (patellar; VISA-P), pain during activity, and global rating of change—were assessed at 6 and 12 weeks and 6 and 12 months. VISA-P score at 12 weeks was the primary outcome. Fifty-seven patients (19 in each group) were included in an intention-to-treat analysis. Secondary outcome measures included pain during activity and patients’ global rating of change. Results: Study retention was 93% at 12 weeks and 79% after 1 year. There was no significant difference in mean change in VISA-P score, pain, or global rating of change among the 3 treatment groups at 12 weeks or any other time point. After 1 year, the mean (SD) outcomes for the LR-PRP, LP-PRP, and saline groups were as follows, respectively: VISA-P—58 (29), 71 (20), and 80 (18); pain—4.0 (2.4), 2.4 (2.3), and 2.0 (1.9); global rating of change—4.7 (1.6), 5.6 (1.0), and 5.7 (1.2) (P > .05 for all outcomes). Conclusion: Combined with an exercise-based rehabilitation program, a single injection of LR-PRP or LP-PRP was no more effective than saline for the improvement of patellar tendinopathy symptoms. Registration: NCT02116946 (ClinicalTrials.gov identifier).

Characterization of Growth Factors, Cytokines, and Chemokines in Bone Marrow Concentrate and Platelet-Rich Plasma: A Prospective Analysis

Background: Platelet-rich plasma (PRP) and bone marrow concentrate (BMC) are orthobiologic therapies with numerous growth factors and other bioactive molecules. Before the clinical utility of PRP and BMC is optimized as a combined therapy or monotherapy, an improved understanding of the components and respective concentrations is necessary. Purpose: To prospectively measure and compare anabolic, anti-inflammatory, and proinflammatory growth factors, cytokines, and chemokines in bone marrow aspirate (BMA), BMC, whole blood, leukocyte-poor PRP (LP-PRP), and leukocyte-rich PRP (LR-PRP) from samples collected and processed concurrently on the same day from patients presenting for elective knee surgery. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Patients presenting for elective knee surgery were prospectively enrolled over a 3-week period. Whole blood from peripheral venous draw and BMA from the posterior iliac crest were immediately processed via centrifugation and manual extraction methods to prepare LR-PRP, LP-PRP, and BMC samples, respectively. BMA, BMC, whole blood, LR-PRP, and LP-PRP samples were immediately assayed and analyzed to measure protein concentrations. Results: BMC had a significantly higher interleukin 1 receptor antagonist (IL-1Ra) concentration than all other preparations (all P < .0009). LR-PRP also had a significantly higher IL-1Ra concentration than LP-PRP (P = .0006). There were no significant differences in IL-1Ra concentration based on age, sex, body mass index, or chronicity of injury in all preparations. LR-PRP had significantly higher concentrations of platelet-derived growth factor AA (PDGF-AA) and PDGF-AB/BB than all other preparations (all P < .0006). LR-PRP also had significantly higher concentrations of matrix metalloproteinase 1 (MMP-1) and soluble CD40 ligand than all other preparations (all P < .004). LP-PRP had significantly higher concentrations of MMPs, namely MMP-2, MMP-3, and MMP-12, than all other preparations (all P < .007). Conclusion: BMC is a clinically relevant source of anti-inflammatory biologic therapy that may be more effective in treating osteoarthritis and for use as an intra-articular biologic source for augmented healing in the postsurgical inflammatory and healing phases, owing to its significantly higher concentration of IL-1Ra as compared with LR-PRP and LP-PRP. Additionally, LR-PRP had a significantly higher concentration of IL-1Ra than LP-PRP. In cases where increased vascularity and healing are desired for pathological or injured tissues, including muscle and tendon, LR-PRP may be optimal given its higher overall concentrations of PDGF, TGF-β, EGF, VEGF, and soluble CD40 ligand.

Platelet-rich plasma (PRP) treatment of noninsertional Achilles tendinopathy in a two case series: no significant difference in effect between leukocyte-rich and leukocyte-poor PRP.

BackgroundThere is a theoretical basis for the treatment of chronic tendinopathies by platelet-rich plasma (PRP), and it can, therefore, be considered a possible treatment of chronic Achilles tendinopathies (CATs), even though the clinical evidence for the use is not clear and, in addition, there is a lack of treatment algorithms and it is unclear which type of PRP is most effective. The objective of this study was through the comparison of two case series to assess: 1) the effect of PRP on CAT and 2) if there is any difference in effect between leukocyte-rich PRP (LR-PRP) and leukocyte-poor PRP (LP-PRP) in the treatment of CAT.Patients and methodsTwo separate series of achilles tenodinopathies treated with either LR-PRP or LP-PRP were evaluated with a natural experiment/quasi-experimental study design, with a short-term (2 months) and long-term (8–42 months) follow-up to assess the effect and stability of the treatment. In total, 84 patients with failed basic treatment for CAT for at least 6 months were treated with either Biomet’s GPS III recovery kit with LR-PRP (36 patients) or with Arthrex ACP LP-PRP (48 patients).ResultsThe overall probability of reaching a minimal clinically important change (MCIC) of at least 30% reduction in visual analog scale (VAS) was in activity (63%) and during rest (81%), and for Victorian Institute of Sport Assessment Scale (VISA-A), it was 61%. There was no statistical difference in change of VISA-A score or VAS between the patients treated with LP-PRP and LR-PRP.ConclusionPRP seems to be a possible treatment when all other treatment regimens have failed, with a reasonably high probability of reaching MCIC. The choice of either LR-PRP or LP-PRP seems to be up to personal preference as there were no significant differences between patients treated with LR-PRP and LP-PRP.

Cellular Components and Growth Factor Content of Platelet-Rich Plasma With a Customizable Commercial System

Background: Platelet-rich plasma (PRP) is an autologous orthobiologic treatment option for musculoskeletal conditions with favorable results in a limited number of high-quality clinical trials. Because different blood-processing methods result in PRP with varying cellular and growth factor content, it is critical that clinicians understand the content of the specific PRP being used in clinical practice. One adjustable system, the Angel System, has few independent laboratory reports on the specific composition of its PRP. The goal of this study was to quantify the cellular and growth factor composition of PRP produced by this system at its lowest hematocrit settings. Hypothesis: The authors hypothesized that the system would significantly concentrate platelets over baseline and, at the lowest hematocrit settings, would reduce leukocytes to produce leukocyte-poor PRP. Study Design: Descriptive laboratory study. Methods: Ten healthy male volunteers donated 150 mL of whole blood for processing. Three separate processing cycles were performed for each sample at the 0%, 1%, and 2% hematocrit settings. The resultant PRP from each cycle was sent for complete blood counts and enzyme-linked immunosorbent assay to quantify the following growth factors: platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF). Results: The system consistently concentrated platelets 5-fold over baseline, with no significant differences among settings. Leukocytes were concentrated at all settings, between 2 and 5 times over baseline. The 0% and 1% settings had significantly lower leukocyte concentrations than the 2% setting. Lymphocytes made up >89% of the leukocyte differential, while neutrophils represented <11% of the differential at each setting. There was a significant increase in PDGF and bFGF, a significant decrease in IGF-1, and no change in VEGF, with no difference among settings. Conclusion: The system consistently concentrated platelets 5 times but was unable to reduce leukocytes, therefore resulting in leukocyte-rich PRP at each setting tested. Leukocytes had a differential composition of >89% lymphocytes and <11% neutrophils. For all settings, PDGF and bFGF were concentrated; IGF-1 was reduced; and VEGF was not significantly different from baseline. Clinical Relevance: These data can serve to guide clinicians considering using this particular PRP system. It consistently yielded leukocyte-rich PRP with a lymphocyte-predominant/neutrophil-reduced profile. Further research is needed to better understand how to apply this specific PRP in clinical practice.

Growth factor levels in leukocyte-poor platelet-rich plasma and correlations with donor age, gender, and platelets in the Japanese population

BackgroundClinical application of platelet-rich-plasma (PRP) has been accelerated to investigate early recovery from various musculoskeletal conditions. It involves the promotion of tissue damage repair through the action of multiple growth factors at physiological concentrations. The composition of PRP differs based on many factors, which may include age and gender. Therefore, we analyzed correlations between age, gender, and platelet counts in PRP with growth factors in Japanese subjects.MethodPeripheral blood was drawn from 39 healthy volunteers between 20 and 49 years of age (age, mean ± standard deviation = 33 ± 8.7 years; gender ratio, male:female = 19:20; BMI, mean ± standard deviation = 22 ± 4.0) and prepared through centrifugation (volume, 6 mL per sample). After being activated with CaCl2, the supernatant was stored. The mean platelet count in PRP was 41.4 ± 12.2 × 104/μL. PRP concentration rate (i.e., PRP/peripheral platelet counts) was 1.8 ± 0.4 times. Growth factor levels (platelet-derived growth factor-BB, transforming growth factor-β1, vascular endothelial growth factor, epidermal growth factor, fibroblast growth factor, insulin-like growth factor-1, and hepatocyte growth factor) were measured using enzyme-linked immunosorbent assay (ELISA), and correlations with age, gender, and PRP platelet counts were statistically analyzed by calculating Spearman’s rank correlation coefficients (r).ResultsAge was negatively correlated with platelet-derived growth factor-BB and insulin-like growth factor-1 (r = − 0.32, − 0.39), and gender had no influence on growth factors. Platelet counts in PRP positively correlated with platelet-derived growth factor-BB, transforming growth factor-β1, epidermal growth factor, and hepatocyte growth factor (r = 0.39, 0.75, 0.71, and 0.48, respectively).ConclusionsThis clinical study shows a significant variation of PRP among individual patients and that this variation is influenced by the age and the platelet counts of the subjects. Our data demonstrate that patient characteristics account for the differences in PRP physiological activity.

Intra-articular Injection of Platelet-Rich Plasma Is Superior to Hyaluronic Acid or Saline Solution in the Treatment of Mild to Moderate Knee Osteoarthritis: A Randomized, Double-Blind, Triple-Parallel, Placebo-Controlled Clinical Trial

To prospectively compare the efficacy of intra-articular injections of platelet-rich plasma (PRP) and hyaluronic acid (HA) with a sham control group (normal saline solution [NS]) for knee osteoarthritis in a randomized, dose-controlled, placebo-controlled, double-blind, triple-parallel clinical trial. A total of 87 osteoarthritic knees (53 patients) were randomly assigned to 1 of 3 groups receiving 3 weekly injections of either leukocyte-poor PRP (31 knees), HA (29 knees), or NS (27 knees). The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score and International Knee Documentation Committee (IKDC) subjective score were collected at baseline and at 1, 2, 6, and 12months after treatment. Data were analyzed using generalized estimating equations. All 3 groups showed statistically significant improvements in both outcome measures at 1month; however, only the PRP group sustained the significant improvement in both the WOMAC score (63.71 ± 20.67, increased by 21%) and IKDC score (49.93 ± 17.74, increased by 40%) at 12months. For the intergroup comparison, except for the first month, there was a statistically significant difference between the PRP and NS groups in both scores throughout the study duration (regression coefficients of 8.72 [P= .0015], 7.94 [P= .0155], and 11.92 [P= .0014] at 2, 6, and 12months, respectively, for WOMAC score, and 9.1 [P= .0001], 10.28 [P= .0002], and 13.97 [P < .0001], respectively, for IKDC score). There was no significant difference in both functional outcomes between the HA and NS groups at any time point. Only the PRP group reached the minimal clinically important difference in the WOMAC score at every evaluation (15%, 21%, 18%, and 21% at 1, 2, 6, and 12months, respectively) and the minimal clinically important difference in the IKDC score at 6months (improvement of 11.6). Intra-articular injections of leukocyte-poor PRP can provide clinically significant functional improvement for at least 1year in patients with mild to moderate osteoarthritis of the knee. Level I, randomized controlled single-center trial.