Efficacy of autologous platelet-rich plasma use for orthopaedic indications: a meta-analysis

Progress in intra-articular therapy

Diarthrodial joints are well suited to intra-articular injection, and the local delivery of therapeutics in this fashion brings several potential advantages to the treatment of a wide range of arthropathies. Possible benefits over systemic delivery include increased bioavailability, reduced systemic exposure, fewer adverse events, and lower total drug costs. Nevertheless, intra-articular therapy is challenging because of the rapid egress of injected materials from the joint space; this elimination is true of both small molecules, which exit via synovial capillaries, and of macromolecules, which are cleared by the lymphatic system. In general, soluble materials have an intra-articular dwell time measured only in hours. Corticosteroids and hyaluronate preparations constitute the mainstay of FDA-approved intra-articular therapeutics. Recombinant proteins, autologous blood products and analgesics have also found clinical use via intra-articular delivery. Several alternative approaches, such as local delivery of cell and gene therapy, as well as the use of microparticles, liposomes, and modified drugs, are in various stages of preclinical development.

Preparation method and growth factor content of platelet concentrate influence the osteogenic differentiation of bone marrow stromal cells

BACKGROUND AIMS

An extensive debate about the clinical benefits of autologous platelet concentrates used as a treatment option for patients with orthopedic injuries is ongoing. The aim of this study was to determine whether different compositions of platelet concentrates may affect the osteogenic differentiation of bone marrow stromal cells (BMSC).

METHODS

Pure platelet-rich plasma (P-PRP) and leukocyte-PRP (L-PRP) were characterized for platelet and leukocyte content. As an indicative marker of the delivery of growth factors (GFs), the release of basic fibroblast growth factor (bFGF) from platelet gel (PG) was measured at 1, 18, 48 and 72 h and at 7 d. The ability of different PGs to induce proliferation and differentiation of BMSC was evaluated by using bioactivity assays.

RESULTS

The platelet recovery was significantly higher in L-PRP, either fresh or frozen. PGs derived from L-PRP and P-PRP showed significant differences in terms of bFGF release and biological activity. bFGF release was faster both in fresh and frozen L-PRP preparations. Moreover, L-PRP samples were able to induce a significantly higher proliferation of BMSC compared with P-PRP or PPP samples. Even though all PG preparations allowed the deposition of mineral nodules in BMSC cultures, the mineralization activity correlated significantly with bFGF levels.

CONCLUSIONS

The biological activity of platelet concentrates differs according to preparation technique, which affects platelet and leukocyte content and GF availability. Because GF levels are not always optimal in subjects with defective bone healing, composition and bioactivity of PRP should be analyzed to test the reliability and potential effectiveness of the regenerative treatment.

Platelet-rich therapies for musculoskeletal soft tissue injuries

BACKGROUND

Platelet-rich therapies are being used increasingly in the treatment of musculoskeletal soft tissue injuries such as ligament, muscle and tendon tears and tendinopathies. These therapies can be used as the principal treatment or as an augmentation procedure (application after surgical repair or reconstruction). Platelet-rich therapies are produced by centrifuging a quantity of the patient's own blood and extracting the active, platelet-rich, fraction. The platelet-rich fraction is applied to the injured tissue; for example, by injection. Platelets have the ability to produce several growth factors, so these therapies should enhance tissue healing. There is a need to assess whether this translates into clinical benefit.

OBJECTIVES

To assess the effects (benefits and harms) of platelet-rich therapies for treating musculoskeletal soft tissue injuries.

SEARCH METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (25 March 2013), the Cochrane Central Register of Controlled Trials (CENTRAL 2013 Issue 2), MEDLINE (1946 to March 2013), EMBASE (1980 to 2013 Week 12) and LILACS (1982 to March 2012). We also searched trial registers (to Week 2 2013) and conference abstracts (2005 to March 2012). No language or publication restrictions were applied.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials that compared platelet-rich therapy with either placebo, autologous whole blood, dry needling or no platelet-rich therapy for people with acute or chronic musculoskeletal soft tissue injuries. Primary outcomes were functional status, pain and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed each study's risk of bias. Disagreement was resolved by discussion or by arbitration by a third author. We contacted trial authors for clarification of methods or missing data. Treatment effects were assessed using risk ratios for dichotomous data and mean differences (MD) or standardised mean differences (SMD) for continuous data, together with 95% confidence intervals. Where appropriate, data were pooled using the fixed-effect model for RR and MD, and the random-effects model for SMD. The quality of the evidence for each outcome was assessed using GRADE criteria.

MAIN RESULTS

We included data from 19 small single centre trials (17 randomised and two quasi-randomised; 1088 participants) that compared platelet-rich therapy with placebo, autologous whole blood, dry needling or no platelet-rich therapy. These trials covered eight clinical conditions: rotator cuff tears (arthroscopic repair) (six trials); shoulder impingement syndrome surgery (one trial); elbow epicondylitis (three trials); anterior cruciate ligament (ACL) reconstruction (four trials), ACL reconstruction (donor graft site application) (two trials), patellar tendinopathy (one trial), Achilles tendinopathy (one trial) and acute Achilles rupture surgical repair (one trial). We also grouped trials into 'tendinopathies' where platelet-rich therapy (PRT) injections were the main treatment (five trials), and surgical augmentation procedures where PRT was applied during surgery (14 trials). Trial participants were mainly male, except in trials including rotator cuff tears, and elbow and Achilles tendinopathies.Three trials were judged as being at low risk of bias; the other 16 were at high or unclear risk of bias relating to selection, detection, attrition or selective reporting, or combinations of these. The methods of preparing platelet-rich plasma (PRP) varied and lacked standardisation and quantification of the PRP applied to the patient.We were able to pool data for our primary outcomes (function, pain, adverse events) for a maximum of 11 trials and 45% of participants. The evidence for all primary outcomes was judged as being of very low quality.Data assessing function in the short term (up to three months) were pooled from five trials that assessed PRT in three clinical conditions and used four different measures. These showed no significant difference between PRT and control (SMD 0.24; 95% confidence interval (CI) -0.07 to 0.56; P value 0.13; I² = 35%; 273 participants; positive values favour PRT). Medium-term function data (at six months) were pooled from six trials that assessed PRT in five clinical conditions and used six different measures. These also showed no difference between groups (SMD 0.06; 95% CI -0.39 to 0.51; P value 0.79; I² = 64%; 262 participants). Long-term function data (at one year) were pooled from 10 trials that assessed PRT in five clinical conditions and used six different measures. These also showed no difference between groups (SMD 0.25, 95% CI -0.07 to 0.57; P value 0.12; I² = 66%; 484 participants). Although the 95% confidence intervals indicate the possibility of a slightly poorer outcome in the PRT group up to a moderate difference in favour of PRT at short- and long-term follow-up, these do not translate into clinically relevant differences.Data pooled from four trials that assessed PRT in three clinical conditions showed a small reduction in short-term pain in favour of PRT on a 10-point scale (MD -0.95, 95% CI -1.41 to -0.48; I² = 0%; 175 participants). The clinical significance of this result is marginal.Four trials reported adverse events; another seven trials reported an absence of adverse events. There was no difference between treatment groups in the numbers of participants with adverse effects (7/241 versus 5/245; RR 1.31, 95% CI 0.48 to 3.59; I² = 0%; 486 participants).In terms of individual conditions, we pooled heterogeneous data for long-term function from six trials of PRT application during rotator cuff tear surgery. This showed no statistically or clinically significant differences between the two groups (324 participants). Pooled data for short-term function for three elbow epicondylitis trials (179 participants) showed a statistically significant difference in favour of PRT, but the clinical significance of this finding is uncertain.The available evidence is insufficient to indicate whether the effects of PRT will differ importantly in individual clinical conditions.

AUTHORS' CONCLUSIONS

Overall, and for the individual clinical conditions, there is currently insufficient evidence to support the use of PRT for treating musculoskeletal soft tissue injuries. Researchers contemplating RCTs should consider the coverage of currently ongoing trials when assessing the need for future RCTs on specific conditions. There is need for standardisation of PRP preparation methods.

Current concepts: tissue engineering and regenerative medicine applications in the ankle joint

Tissue engineering and regenerative medicine (TERM) has caused a revolution in present and future trends of medicine and surgery. In different tissues, advanced TERM approaches bring new therapeutic possibilities in general population as well as in young patients and high-level athletes, improving restoration of biological functions and rehabilitation. The mainstream components required to obtain a functional regeneration of tissues may include biodegradable scaffolds, drugs or growth factors and different cell types (either autologous or heterologous) that can be cultured in bioreactor systems (in vitro) prior to implantation into the patient. Particularly in the ankle, which is subject to many different injuries (e.g. acute, chronic, traumatic and degenerative), there is still no definitive and feasible answer to ‘conventional’ methods. This review aims to provide current concepts of TERM applications to ankle injuries under preclinical and/or clinical research applied to skin, tendon, bone and cartilage problems. A particular attention has been given to biomaterial design and scaffold processing with potential use in osteochondral ankle lesions.

The efficacy of platelet-rich plasma in the treatment of symptomatic knee osteoarthritis: a systematic review with quantitative synthesis

PURPOSE

The purpose of this systematic review was to synthesize the available Level I and Level II literature on platelet-rich plasma (PRP) as a therapeutic intervention in the management of symptomatic knee osteoarthritis (OA).

METHODS

A systematic review of Medline, Embase, Cochrane Central Register of Controlled Trials, PubMed, and www.clinicaltrials.gov was performed to identify all randomized controlled trials and prospective cohort studies that evaluated the clinical efficacy of PRP versus a control injection for knee OA. A random-effects model was used to evaluate the therapeutic effect of PRP at 24 weeks by use of validated outcome measures (Western Ontario and McMaster Universities Arthritis Index, visual analog scale for pain, International Knee Documentation Committee Subjective Knee Evaluation Form, and overall patient satisfaction).

RESULTS

Six Level I and II studies satisfied our inclusion criteria (4 randomized controlled trials and 2 prospective nonrandomized studies). A total of 577 patients were included, with 264 patients (45.8%) in the treatment group (PRP) and 313 patients (54.2%) in the control group (hyaluronic acid [HA] or normal saline solution [NS]). The mean age of patients receiving PRP was 56.1 years (51.5% male patients) compared with 57.1 years (49.5% male patients) for the group receiving HA or NS. Pooled results using the Western Ontario and McMaster Universities Arthritis Index scale (4 studies) showed that PRP was significantly better than HA or NS injections (mean difference, -18.0 [95% confidence interval, -28.8 to -8.3]; P < .001). Similarly, the International Knee Documentation Committee scores (3 studies) favored PRP as a treatment modality (mean difference, 7.9 [95% confidence interval, 3.7 to 12.1]; P < .001). There was no difference in the pooled results for visual analog scale score or overall patient satisfaction. Adverse events occurred more frequently in patients treated with PRP than in those treated with HA/placebo (8.4% v 3.8%, P = .002).

CONCLUSIONS

As compared with HA or NS injection, multiple sequential intra-articular PRP injections may have beneficial effects in the treatment of adult patients with mild to moderate knee OA at approximately 6 months. There appears to be an increased incidence of nonspecific adverse events among patients treated with PRP.

LEVEL OF EVIDENCE

Level II, systematic review of Level I and II studies.

Comparative effectiveness of platelet-rich plasma injections for treating knee joint cartilage degenerative pathology: a systematic review and meta-analysis

OBJECTIVE

To explore the effectiveness of platelet-rich plasma (PRP) in treating cartilage degenerative pathology in knee joints.

DATA SOURCES

Electronic databases, including PubMed and Scopus, were searched from the earliest record to September 2013.

STUDY SELECTION

We included single-arm prospective studies, quasi-experimental studies, and randomized controlled trials that used PRP to treat knee chondral degenerative lesions. Eight single-arm studies, 3 quasi-experimental studies, and 5 randomized controlled trials were identified, comprising 1543 participants.

DATA EXTRACTION

We determined effect sizes for the selected studies by extracting changes in functional scales after the interventions and compared the PRP group pooled values with the pretreatment baseline and the groups receiving placebo or hyaluronic acid (HA) injections.

DATA SYNTHESIS

PRP injections in patients with knee degenerative pathology showed continual efficacy for 12 months compared with their pretreatment condition. The effectiveness of PRP was likely better and more prolonged than that of HA. Injection doses ≤2, the use of a single-spinning approach, and lack of additional activators led to an uncertainty in the treatment effects. Patients with lower degrees of cartilage degeneration achieved superior outcomes as opposed to those affected by advanced osteoarthritis.

CONCLUSIONS

PRP application improves function from basal evaluations in patients with knee joint cartilage degenerative pathology and tends to be more effective than HA administration. Discrepancy in the degenerative severity modifies the treatment responses, leading to participants with lower degrees of degeneration benefiting more from PRP injections.

Effectiveness of bisphosphonate analogues and functional electrical stimulation on attenuating post-injury osteoporosis in spinal cord injury patients- a systematic review and meta-analysis

BACKGROUND

Various pharmacologic and non-pharmacologic approaches have been applied to reduce sublesional bone loss after spinal cord injury (SCI), and the results are inconsistent across the studies. The objective of this meta-analysis was to investigate whether the two most-studied interventions, bisphosphonate analogues and functional electrical stimulation (FES), could effectively decrease bone mineral density (BMD) attenuation and/or restore lost BMD in the SCI population.

METHODS

Randomized controlled trials, quasi-experimental studies, and prospective follow-up studies employing bisphosphonates or FES to treat post-SCI osteoporosis were identified in PubMed and Scopus. The primary outcome was the percentage of BMD change from baseline measured by dual-energy X-ray absorptiometry (DEXA) or computed tomography (CT). Data were extracted from four points: the 3rd, 6th, 12th, and 18th month after intervention.

RESULTS

A total of 19 studies were included in the analysis and involved 364 patients and 14 healthy individuals. Acute SCI participants treated with bisphosphonate therapy demonstrated a trend toward less bone loss than participants who received placebos or usual care. A significant difference in BMD decline was noted between both groups at the 3rd and 12th month post-medication. The subgroup analysis failed to show the superiority of intravenous bisphosphonate over oral administration. Regarding FES training, chronic SCI patients had 5.96% (95% CI, 2.08% to 9.84%), 7.21% (95%CI, 1.79% to 12.62%), and 9.56% (95% CI, 2.86% to 16.26%) increases in BMD at the 3rd, 6th, and 12th months post-treatment, respectively. The studies employing FES ≥ 5 days per week were likely to have better effectiveness than studies using FES ≤ 3 days per week.

CONCLUSIONS

Our meta-analysis indicated bisphosphonate administration early following SCI effectively attenuated sublesional bone loss. FES intervention for chronic SCI patients could significantly increase sublesional BMD near the site of maximal mechanical loading.

Application of Platelet-Rich Plasma to Disorders of the Knee Joint

IMPORTANCE

The promising therapeutic potential and regenerative properties of platelet-rich plasma (PRP) have rapidly led to its widespread clinical use in musculoskeletal injury and disease. Although the basic scientific rationale surrounding PRP products is compelling, the clinical application has outpaced the research.

OBJECTIVE

The purpose of this article is to examine the current concepts around the basic science of PRP application, different preparation systems, and clinical application of PRP in disorders in the knee.

EVIDENCE ACQUISITION

A systematic search of PubMed for studies that evaluated the basic science, preparation and clinical application of platelet concentrates was performed. The search used terms, including platelet-rich plasma or PRP preparation, activation, use in the knee, cartilage, ligament, and meniscus. Studies found in the initial search and related studies were reviewed.

RESULTS

A comprehensive review of the literature supports the potential use of PRP both nonoperatively and intraoperatively, but highlights the absence of large clinical studies and the lack of standardization between method, product, and clinical efficacy. Conclusions and Relevance. In addition to the call for more randomized, controlled clinical studies to assess the clinical effect of PRP, at this point, it is necessary to investigate PRP product composition and eventually have the ability to tailor the therapeutic product for specific indications.

Platelet-rich plasma for managing pain and inflammation in osteoarthritis

Osteoarthritis (OA) is a common disease involving joint damage, an inadequate healing response and progressive deterioration of the joint architecture. Autologous blood-derived products, such as platelet-rich plasma (PRP), are key sources of molecules involved in tissue repair and regeneration. These products can deliver a collection of bioactive molecules that have important roles in fundamental processes, including inflammation, angiogenesis, cell migration and metabolism in pathological conditions, such as OA. PRP has anti-inflammatory properties through its effects on the canonical nuclear factor κB signalling pathway in multiple cell types including synoviocytes, macrophages and chondrocytes. PRP contains hundreds of different molecules; cells within the joint add to this milieu by secreting additional biologically active molecules in response to PRP. The net results of PRP therapy are varied and can include angiogenesis, the production of local conditions that favour anabolism in the articular cartilage, or the recruitment of repair cells. However, the molecules found in PRP that contribute to angiogenesis and the protection of joint integrity need further clarification. Understanding PRP in molecular terms could help us to exploit its therapeutic potential, and aid the development of novel treatments and tissue-engineering approaches, for the different stages of joint degeneration.

Platelet-rich plasma for arthroscopic repair of large to massive rotator cuff tears: a randomized, single-blind, parallel-group trial

BACKGROUND

Platelet-rich plasma (PRP) is expected to have a biological augmentation potential in the healing of various diseases and injuries, including rotator cuff tears. However, few evaluations have been performed specifically for large to massive tears.

PURPOSE

To assess the efficacy of PRP augmentation in patients undergoing arthroscopic repair for large to massive rotator cuff tears.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 48 patients scheduled for arthroscopic repair of large to massive rotator cuff tears were randomly assigned to receive either PRP-augmented (PRP group) or conventional treatment (conventional group). In the PRP group, 3 PRP gels (3 × 3 mL) were applied to each patient between the torn end and the greater tuberosity. The primary outcome measure was the retear rate assessed by magnetic resonance imaging (MRI) or computed tomographic arthrography (CTA) at a minimum of 9 months after surgery. Secondary outcome measures included pain, range of motion, muscle strength, overall satisfaction, functional scores, and the change in cross-sectional area (CSA) of the supraspinatus.

RESULTS

The retear rate of the PRP group (20.0%) was significantly lower than that of the conventional group (55.6%) (P = .023). Clinical outcomes showed no statistical difference between the 2 groups (all P > .05) except for the overall function (P = .043). The change in 1-year postoperative and immediately postoperative CSA was significantly different between the 2 groups: -15.54 ± 94.34 mm² in the PRP group versus -85.62 ± 103.57 mm² in the conventional group (P = .047).

CONCLUSION

The application of PRP for large to massive rotator cuff repairs significantly improved structural outcomes, as evidenced by a decreased retear rate and increased CSA of the supraspinatus compared with repairs without PRP augmentation. While there was no significant difference in clinical outcomes except the overall shoulder function after 1-year follow-up, better structural outcomes in the PRP group might suggest improved clinical outcomes at longer term follow-up.

Platelets increase while serum reduces the differentiation and activity of osteoclasts in vitro

Platelets modulate formation of osteoclasts and osteoblasts, but research with different preparations of platelets remains inconclusive. Here, we assessed whether serum components modulate the effect of platelet preparations. In murine bone marrow cultures, osteoclastogenesis was investigated in the presence of platelet-released supernatant (PRS), serum containing PRS (SC-PRS), and serum. Osteoclastogenesis was quantified by the numbers of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells, TRAP activity and resorption assays. Also human osteoclastogenesis assays were performed. Viability and proliferation were tested by MTT and (3) [H]thymidine incorporation assays, respectively. Osteoblastogenesis was assessed by histochemical staining for alkaline phosphatase-of murine bone marrow cultures and human MG63 cells. We found PRS to increase the number of TRAP(+) multinucleated cells in the early phase and TRAP activity in the later phase of osteoclastogenesis. SC-PRS and serum decreased the number and activity of TRAP(+) multinucleated cells. Both serum containing preparations reduced viability and proliferation of hematopoietic progenitors. PRS decreased the numbers of alkaline phosphatase-positive colonies while SC-PRS and serum increased osteoblastmarkers in MG63. Proliferation of MG63 was stimulated by all preparations. These results show that activated platelets support osteoclastogenesis, while platelet preparations that contain serum components decrease osteoclastogenesis and increase osteoblastogenesis in vitro, suggesting that serum components modulate the effects of platelets on osteoclastogenesis and osteoblastogenesis.

Progression of patellar tendinitis following treatment with platelet-rich plasma: case reports

PURPOSE

The use of platelet-rich plasma (PRP) is becoming more attractive given its favourable side effect profile and autologous nature, leading to rapid clinical adoption in the absence of high-level evidence. We are presenting three patients who developed a progression of patellar tendinitis following treatment, which to our knowledge is the first report of worsening of patellar tendinitis following PRP therapy.

METHODS

The records of three patients with symptom exacerbation of patellar tendinitis following treatment with PRP were reviewed. IRB exemption was obtained. Clinical and operative records, radiographs, and MR imaging were reviewed for all patients.

RESULTS

Three patients reported to our clinic for a second opinion with symptoms of anterior knee pain consistent with patellar tendinitis. Each patient had previously been treated with PRP therapy due to prolonged symptoms. Clinical and radiological findings following treatment included patellar tendon thickening, worsening pain, discontinuation of athletic participation in all three patients, and osteolysis of the distal pole of the patella in one patient identified during surgical intervention.

CONCLUSIONS

Growing interest in the use of autologous products for the management of chronic tendinopathies has led to widespread clinical implementation with minimal scientific support. It is tempting to apply a new treatment for management of a difficult clinical entity, especially when the risk/benefit ratio appears favourable. However, caution must be exercised as unexpected results may be encountered.

LEVEL OF EVIDENCE

Case reports, level V.

Platelet lysate as replacement for fetal bovine serum in mesenchymal stromal cell cultures

Mesenchymal stromal cells (MSC) emerged as highly attractive in cell-based regenerative medicine. Initially thought to provide cells capable of differentiation towards mesenchymal cell types (osteoblasts, chondrocytes, adipocytes etc.), by and by potent immunoregulatory and pro-regenerative activities have been discovered, broadening the field of potential applications from bone and cartilage regeneration to wound healing and treatment of autoimmune diseases. Due to the limited frequency in most tissue sources, ex vivo expansion of MSC is required compliant with good manufacturing practice (GMP) guidelines to yield clinically relevant cell doses. Though, still most manufacturing protocols use fetal bovine serum (FBS) as cell culture supplement to isolate and to expand MSC. However, the high lot-to-lot variability as well as risk of contamination and immunization call for xenogenic-free culture conditions. In terms of standardization, chemically defined media appear as the ultimate achievement. Since these media need to maintain all key cellular and therapy-relevant features of MSC, the development of chemically defined media is still - albeit highly investigated - only in its beginning. The current alternatives to FBS rely on human blood-derived components: plasma, serum, umbilical cord blood serum, and platelet derivatives like platelet lysate. Focusing on quality aspects, the latter will be addressed within this review.

Platelet-rich plasma in the pathologic processes of cartilage: review of basic science evidence

PURPOSE

The purpose of this study was to systematically review the basic science evidence for the use of platelet-rich plasma (PRP) in the treatment of pathologic processes of cartilage, both as an adjunct to cartilage repair and as a conservative management strategy for osteoarthritis, with the intent of determining the effect of PRP and whether a proof of concept for its use has been established to facilitate further investigation at a clinical level.

METHODS

Using the terms "platelet-rich plasma OR PRP OR autologous conditioned plasma OR ACP AND cartilage OR chondrocytes OR chondrogenesis OR osteoarthritis OR arthritis" we searched EMBASE and PubMed/Medline in April 2012. Two authors performed the search, 3 authors independently assessed the studies for inclusion, and 2 authors extracted the data. Extracted data included cytologic analysis of PRP, study design, and results.

RESULTS

Twenty-one studies (12 in vitro, 8 in vivo, one in vitro and in vivo) met the inclusion criteria. The effects of PRP in these studies included increasing chondrocyte and mesenchymal stem cell proliferation, proteoglycan deposition, and type II collagen deposition. PRP was also found to increase the cell viability of chondrocytes and the migration and chondrogenic differentiation of mesenchymal stem cells (MSCs) and to inhibit the effect of catabolic cytokines. In vivo, PRP was used as an adjunct to concomitant surgical management, including microfracture surgery and implant, scaffold, and graft insertion. Not all studies concluded that PRP has a positive effect on cartilage repair.

CONCLUSIONS

The current basic science evidence suggests that PRP has several potential effects on cartilage repair and osteoarthritis, and a proof of concept has been established. Well-designed randomized controlled trials (RCTs) are needed to extrapolate this evidence to the clinical setting.

Future trends for unicompartmental arthritis of the knee: injectables & stem cells

Arthritis is one of the most frequent musculoskeletal problems, causing pain, disability, and a significant economic burden. In this article, we discuss current nonsurgical injectable treatment options as well as future trends for cartilage lesions and early arthritis of the knee. We cover some potential treatments for knee osteoarthritis, including stem cell and gene therapies.

HGF mediates the anti-inflammatory effects of PRP on injured tendons

Platelet-rich plasma (PRP) containing hepatocyte growth factor (HGF) and other growth factors are widely used in orthopaedic/sports medicine to repair injured tendons. While PRP treatment is reported to decrease pain in patients with tendon injury, the mechanism of this effect is not clear. Tendon pain is often associated with tendon inflammation, and HGF is known to protect tissues from inflammatory damages. Therefore, we hypothesized that HGF in PRP causes the anti-inflammatory effects. To test this hypothesis, we performed in vitro experiments on rabbit tendon cells and in vivo experiments on a mouse Achilles tendon injury model. We found that addition of PRP or HGF decreased gene expression of COX-1, COX-2, and mPGES-1, induced by the treatment of tendon cells in vitro with IL-1β. Further, the treatment of tendon cell cultures with HGF antibodies reduced the suppressive effects of PRP or HGF on IL-1β-induced COX-1, COX-2, and mPGES-1 gene expressions. Treatment with PRP or HGF almost completely blocked the cellular production of PGE2 and the expression of COX proteins. Finally, injection of PRP or HGF into wounded mouse Achilles tendons in vivo decreased PGE2 production in the tendinous tissues. Injection of platelet-poor plasma (PPP) however, did not reduce PGE2 levels in the wounded tendons, but the injection of HGF antibody inhibited the effects of PRP and HGF. Further, injection of PRP or HGF also decreased COX-1 and COX-2 proteins. These results indicate that PRP exerts anti-inflammatory effects on injured tendons through HGF. This study provides basic scientific evidence to support the use of PRP to treat injured tendons because PRP can reduce inflammation and thereby reduce the associated pain caused by high levels of PGE2.

Growth factor release from platelet concentrates: analytic quantification and characterization for clinical applications

BACKGROUND AND OBJECTIVES

Clinical use of plasma rich in growth factors requires biochemical product control. We aimed to measure and modulate concentrations of growth factors in solutions deriving from platelet apheresis or whole blood.

MATERIALS AND METHODS

Growth factor concentrations were measured 5', 10', 20', 30', 60' after CaCl2 was added at 40°C to platelet-apheresis products (n = 39) or after 60' in platelet concentrates from whole blood (n = 13). Growth factor release was also obtained in platelet apheresis a) by incubation at 22°C or 40°C for 10' or 30' (n = 4); b) by repeated freeze-thaw (n = 9).

RESULTS

Fibroblast growth factor (FGF), platelet-derived growth factor (PDGF) isoforms AA and AB and transforming growth factor beta (TGF-β) concentrations (pg/10(9 ) plt) were 25-60% higher in growth factors solutions from whole blood compared to platelet apheresis. Vascular endothelial growth factor (VEGF), TGF-β and PDGF isoforms were released early (5-10') during incubation: TGF-β concentration increased also at 30'. FGF and epidermal growth factor (EGF) were released only after 30'. Incubation at 40°C/10' increased VEGF (+70%) and decreased EGF (-30%) and PDGF-BB (-50%) versus 22°C/30'. Shock significantly increased TGF-β (1.6-fold), EGF (1.5-fold), FGF (4.5-fold) and lowered PDGF isoforms (0.2- to 0.5-fold) versus prolonged incubation at 40°C.

CONCLUSION

Platelets from platelet apheresis and whole-blood release all investigated growth factors. The release can be regulated controlling incubation time and/or temperature and performing cell lysis.

MMP inhibition as a potential method to augment the healing of skeletal muscle and tendon extracellular matrix

The extracellular matrix (ECM) of skeletal muscle and tendon is composed of different types of collagen molecules that play important roles in the transmission of forces throughout the body, and in the repair and regeneration of injured tissues. Fibroblasts are the primary cells in muscle and tendon that maintain, repair, and modify the ECM in response to mechanical loading, injury, and inactivity. Matrix metalloproteinases (MMPs) are enzymes that digest collagen and other structural molecules, which are synthesized and excreted by fibroblasts. MMPs are required for baseline ECM homeostasis, but disruption of MMP regulation due to injury or disease can alter the normal ECM architecture and prevent proper force transmission. Chronic injuries and diseases of muscles and tendons can be severely debilitating, and current therapeutic modalities to enhance healing are quite limited. This review will discuss the mechanobiology of MMPs, and the potential use of MMP inhibitors to improve the treatment of injured and diseased skeletal muscle and tendon tissue.

An in vitro evaluation of the anti-inflammatory effects of platelet-rich plasma, ketorolac, and methylprednisolone

PURPOSE

The purpose of this study was to quantify the extent of the anti-inflammatory effect of platelet-rich plasma (PRP) in a controlled in vitro environment.

METHODS

Through the stimulation of human umbilical vein endothelial cells with inflammatory cytokines (tumor necrosis factor α and interferon γ), cell adhesion molecule expression (E-selectin, vascular cell adhesion molecule, and human leukocyte antigen DR) and PRP's anti-inflammatory effect can be measured. PRP was produced from 3 individuals using a single-spin (PRPLP) process. Treatment groups include negative (unstimulated) controls, positive (stimulated) controls, ketorolac tromethamine, methylprednisolone, PRP, ketorolac-PRP, and methylprednisolone-PRP. A fluorescence assay of the cellular inflammation markers was measured by the BioTek Synergy HT plate reader (BioTek Instruments, Winooski, VT) at 0, 1, 2, and 5 days.

RESULTS

At days 2 and 5, methylprednisolone treatment showed a 2.1- to 5.8-fold reduction (P < .05) in inflammation markers over PRP. In addition, PRP and ketorolac showed a 1.4- to 2.5-fold reduction (P < .05) in cellular inflammation markers over the control. There was no statistically significant difference between ketorolac and PRP.

CONCLUSIONS

Although PRP and ketorolac reduced cellular inflammation markers (E-selectin, vascular cell adhesion molecule, and human leukocyte antigen DR) compared with control, neither caused as great a reduction as methylprednisolone.

CLINICAL RELEVANCE

Although PRP and ketorolac did not produce as significant a reduction in cellular inflammation markers as methylprednisolone, they reduced cellular inflammation compared with the control. These agents may have clinical application as injectable anti-inflammatory medications.

Treatment with platelet-rich plasma is more effective than placebo for knee osteoarthritis: a prospective, double-blind, randomized trial

BACKGROUND

Specific growth factors have been proposed as therapeutic proteins for cartilage repair.

HYPOTHESIS

Platelet-rich plasma (PRP) provides symptomatic relief in early osteoarthritis (OA) of the knee.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 78 patients (156 knees) with bilateral OA were divided randomly into 3 groups. Group A (52 knees) received a single injection of PRP, group B (50 knees) received 2 injections of PRP 3 weeks apart, and group C (46 knees) received a single injection of normal saline. White blood cell (WBC)-filtered PRP with a platelet count 3 times that of baseline (PRP type 4B) was administered in all. All the groups were homogeneous and comparable in baseline characteristics. Clinical outcome was evaluated using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) questionnaire before treatment and at 6 weeks, 3 months, and 6 months after treatment. They were also evaluated for pain by a visual analog scale, and overall satisfaction with the procedure and complications were noted.

RESULTS

Statistically significant improvement in all WOMAC parameters was noted in groups A and B within 2 to 3 weeks and lasting until the final follow-up at 6 months, with slight worsening at the 6-month follow-up. The mean WOMAC scores (pain, stiffness, physical function, and total score) for group A at baseline were 10.18, 3.12, 36.56, and 49.86, respectively, and at final follow-up were 5.00, 2.10, 20.08, and 27.18, respectively, showing significant improvement. Similar improvement was noted in group B (mean WOMAC scores at baseline: 10.62, 3.50, 39.10, and 53.20, respectively; mean WOMAC scores at final follow-up: 6.18, 1.88, 22.40, and 30.48, respectively). In group C, the mean WOMAC scores deteriorated from baseline (9.04, 2.70, 33.80, and 45.54, respectively) to final follow-up (10.87, 2.76, 39.46, and 53.09, respectively). The 3 groups were compared with each other, and no improvement was noted in group C as compared with groups A and B (P < .001). There was no difference between groups A and B, and there was no influence of age, sex, weight, or body mass index on the outcome. Knees with Ahlback grade 1 fared better than those with grade 2. Mild complications such as nausea and dizziness, which were of short duration, were observed in 6 patients (22.2%) in group A and 11 patients (44%) in group B.

CONCLUSION

A single dose of WBC-filtered PRP in concentrations of 10 times the normal amount is as effective as 2 injections to alleviate symptoms in early knee OA. The results, however, deteriorate after 6 months. Both groups treated with PRP had better results than did the group injected with saline only.

Ultrasound-guided injection of platelet-rich plasma in chronic Achilles and patellar tendinopathy

PURPOSE

The efficacy of platelet-rich plasma (PRP) in the treatment and healing of chronic tendinopathy through stimulation of cell proliferation and total collagen production has been demonstrated by both in vitro and in vivo studies. The aim of this study is to evaluate the effectiveness of ultrasound (US)-guided autologous PRP injections in patellar and Achilles tendinopathy.

MATERIALS AND METHODS

Autologous PRP was injected under US-guidance into the Achilles and patellar tendons (30 Achilles tendons, 28 patellar tendons) in 48 prospectively selected patients (30 males, 18 females, mean age 38 ± 16 years, range 20-61 years). All patients were previously evaluated according to the Victoria Institute of Sport Assessment (VISA) scale, which assessed pain and activity level, and they all underwent US of the tendon before treatment and at follow-up after 20 days and 6 months. Statistical analysis was performed with Chi-square and Wilcoxon tests.

RESULTS

20 days after PRP injection the patients presented a non-significant improvement of clinical symptoms. At the 6-month follow-up VISA score increased from a mean value of 57-75.5 (p < .01). US evaluation revealed a reduction of hypoechoic areas in 26 tendons (p < .01) associated with a widespread improvement of fibrillar echotexture of the tendon and reduced hypervascularity at power Doppler.

CONCLUSION

PRP injection in patellar and Achilles tendinopathy results in a significant and lasting improvement of clinical symptoms and leads to recovery of the tendon matrix potentially helping to prevent degenerative lesions. US-guidance allows PRP injection into the tendon with great accuracy.

Platelet-rich plasma therapy - future or trend?

Chronic complex musculoskeletal injuries that are slow to heal pose challenges to physicians and researchers alike. Orthobiologics is a relatively newer science that involves application of naturally found materials from biological sources (for example, cell-based therapies), and offers exciting new possibilities to promote and accelerate bone and soft tissue healing. Platelet-rich plasma (PRP) is an orthobiologic that has recently gained popularity as an adjuvant treatment for musculoskeletal injuries. It is a volume of fractionated plasma from the patient's own blood that contains platelet concentrate. The platelets contain alpha granules that are rich in several growth factors, such as platelet-derived growth factor, transforming growth factor-β, insulin-like growth factor, vascular endothelial growth factor and epidermal growth factor, which play key roles in tissue repair mechanisms. PRP has found application in diverse surgical fields to enhance bone and soft-tissue healing by placing supra-physiological concentrations of autologous platelets at the site of tissue damage. The relative ease of preparation, applicability in the clinical setting, favorable safety profile and possible beneficial outcome make PRP a promising therapeutic approach for future regenerative treatments. However, there is a large knowledge gap in our understanding of PRPs mechanism of action, which has raised skepticism regarding its potential efficacy and use. Thus, the aim of this review is to describe the various factors proposed to contribute to the biological activity of PRP, and the published pre-clinical and clinical evidence to support it. Additionally, we describe the current techniques and technology for PRP preparation, and review the present shortcomings of this therapy that will need to be overcome if it is to gain broad acceptance.