The Role of Platelet-Rich Plasma in Cartilage Pathology: An Updated Systematic Review of the Basic Science Evidence

Efficacy of Platelet-Rich Plasma Intra-articular Injections in Hip and Knee Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disorder that causes significant pain and functional limitations. Platelet-rich plasma (PRP) therapy has gained considerable attention in recent years in the treatment of musculoskeletal injuries. In this narrative review, we aim to investigate the role of intra-articular PRP injections in the treatment of knee and hip OA. The review also discusses different classifications of PRP based on composition. Furthermore, this narrative review also identified various limitations of PRP therapy in OA. PRP is classified into different types based on cell content and fibrin architecture, including pure platelet-rich plasma (P-PRP), leukocyte- and platelet-rich plasma (L-PRP), pure platelet-rich fibrin (P-PRF), and leukocyte- and platelet-rich fibrin (L-PRF). Various clinical trials have shown that PRP is an effective option for the treatment of knee and hip OA. However, the superiority of PRP over hyaluronic acid has been reported inconsistently. This variability can be attributed to PRP preparation techniques. The safety profiles of PRP are generally favorable and the adverse effects are generally mild in nature. Although there is sufficient evidence in support of PRP in the treatment of OA, the long-term effects of PRP have not been reported. Further studies should focus on longer follow-up periods to identify the efficacy and safety of PRP in treating knee OA. There is also a need for standardization of PRP preparations in OA management.

Allogeneic platelet-rich plasma for knee osteoarthritis in patients with primary immune thrombocytopenia: A randomized clinical trial

The treatment of painful KOA in adult patients with ITP has not been well studied yet. We conducted a prospective, double-blind, randomized, placebo-controlled trial to evaluate the efficacy of intra-articular allogeneic PRP injections on symptoms and joint structure in patients with KOA and ITP. 80 participants were randomly allocated in a 1:1 ratio to allogeneic PRP group or saline group. The primary outcome was the WOMAC total score at 12 months post-injection. The number of patients in each group who achieved MCID of primary outcome showed a statistically significant difference only at 3-month (27/39 vs. 5/39, p = 0.001) and 6-month (15/39 vs. 3/38, p = 0.032). The difference in WOMAC total score exceeded the MCID only at 3 month (mean difference of -15.1 [95% CI -20.7 to -9.5], p < 0.001). Results suggest that allogeneic PRP was superior to placebo only with respect to symptoms at 3-month of follow-up.

Experts Achieve Consensus on a Majority of Statements Regarding Platelet-Rich Plasma Treatments for Treatment of Musculoskeletal Pathology

PURPOSE

To establish consensus statements on platelet-rich plasma (PRP) for the treatment of musculoskeletal pathologies.

METHODS

A consensus process on the treatment of PRP using a modified Delphi technique was conducted. Thirty-five orthopaedic surgeons and sports medicine physicians participated in these consensus statements on PRP. The participants were composed of representatives of the Biologic Association, representing 9 international orthopaedic and musculoskeletal professional societies invited due to their active interest in the study of orthobiologics. Consensus was defined as achieving 80% to 89% agreement, strong consensus was defined as 90% to 99% agreement, and unanimous consensus was indicated by 100% agreement with a proposed statement.

RESULTS

There was consensus on 62% of statements about PRP.

CONCLUSIONS

(1) PRP should be classified based on platelet count, leukocyte count, red blood count, activation method, and pure-plasma versus fibrin matrix; (2) PRP characteristics for reporting in research studies are platelet count, leukocyte count, neutrophil count, red blood cell count, total volume, the volume of injection, delivery method, and the number of injections; (3) the prognostic factors for those undergoing PRP injections are age, body mass index, severity/grade of pathology, chronicity of pathology, prior injections and response, primary diagnosis (primary vs postsurgery vs post-trauma vs psoriatic), comorbidities, and smoking; (4) regarding age and body mass index, there is no minimum or maximum, but clinical judgment should be used at extremes of either; (5) the ideal dose of PRP is undetermined; and (6) the minimal volume required is unclear and may depend on the pathology.

LEVEL OF EVIDENCE

Level V, expert opinion.

Recent Achievements in the Development of Biomaterials Improved with Platelet Concentrates for Soft and Hard Tissue Engineering Applications

Platelet concentrates such as platelet-rich plasma, platelet-rich fibrin or concentrated growth factors are cost-effective autologous preparations containing various growth factors, including platelet-derived growth factor, transforming growth factor β, insulin-like growth factor 1 and vascular endothelial growth factor. For this reason, they are often used in regenerative medicine to treat wounds, nerve damage as well as cartilage and bone defects. Unfortunately, after administration, these preparations release growth factors very quickly, which lose their activity rapidly. As a consequence, this results in the need to repeat the therapy, which is associated with additional pain and discomfort for the patient. Recent research shows that combining platelet concentrates with biomaterials overcomes this problem because growth factors are released in a more sustainable manner. Moreover, this concept fits into the latest trends in tissue engineering, which include biomaterials, bioactive factors and cells. Therefore, this review presents the latest literature reports on the properties of biomaterials enriched with platelet concentrates for applications in skin, nerve, cartilage and bone tissue engineering.

Are patients with knee osteoarthritis aware that platelet-rich plasma is a treatment option?

Osteoarthritis (OA) is a prevalent joint disease, particularly affecting the knees. This condition is often managed through various treatments, including intra-articular injections such as corticosteroids (CS), hyaluronic acid (HA), and platelet-rich plasma (PRP). PRP has shown promising outcomes in recent studies although it does lack strong endorsement in some clinical guidelines due to inconsistent results and lack of standardized results. This study was conducted to assess patient awareness and the frequency of PRP offered for the treatment of knee OA, compared to CS and HA. In a cross-sectional study, 46 knee OA patients were surveyed regarding their knowledge and experiences of CS, HA, and PRP injections. The questionnaires were administered between September 2022 and February 2023. Additionally, the study evaluated the severity of patients knee OA, using the Western Ontario and McMaster Universities Arthritis Index, and gathered demographic information from the participants. CS injections were offered to 93.5%, and 100% of participants had previously heard of this type of injection. HA injections were offered to 37%, and 65.9% of participants had heard of them. PRP was offered to 2%, and 6.5% had ever heard of it. This study underscores the limited awareness and utilization of PRP among knee OA patients. Patients and physicians need to be more informed of all of the treatment options available for knee OA, especially orthobiologics such as PRP. Future research in larger, diverse populations is needed.

Orthobiologics as an adjunct in treatment of femoroacetabular impingement syndrome: cell-based therapies facilitate improved postoperative outcomes in the setting of acetabular chondral lesions-a systematic review

PURPOSE

To evaluate studies utilizing orthobiologics in the management of femoroacetabular impingement syndrome (FAIS) to (1) assess the indications for usage, and (2) analyze patient-reported outcome measures (PROM) following treatment. It was hypothesized that orthobiologics would (1) be utilized for symptomatic FAIS in the setting of labral or chondral pathology, and (2) improve PROM at most recent follow-up.

METHODS

The Pubmed, Ovid Medline, Cochrane, and Web of Science databases were searched for clinical studies evaluating orthobiologics [hyaluronic acid (HA), platelet-rich plasma (PRP), or cell-based therapy (CBT) for treatment of FAIS. Exclusion criteria included orthobiologics used in conjunction with cartilage transfer or scaffolding procedures and a primary indication other than FAIS. Data collection included patient demographics, indications, and baseline and most recent PROM.

RESULTS

Eleven studies (one level I, four level II, four level III, and two level IV evidence) met inclusion criteria, consisting of 440 patients with mean ages ranging from 32.8 to 47 years. All 11 studies demonstrated an improvement in PROM from baseline to most-recent follow-up. Four studies administered PRP either intraoperatively or the day after surgery as an adjunct to labral repair. CBT was used intraoperatively in the setting of acetabular chondral lesions (three studies) and labral repair (one study). When comparing to a control group at most recent follow-up, three PRP cohorts demonstrated similar PROM (n.s.), while one PRP group exhibited worse visual analog pain scores (2.5 vs. 3.4, p = 0.005) and modified Harris Hip Scores (mHHS) (82.6 vs. 78.7, p = 0.049). The four CBT studies reported favorable results compared to a control group, with a significantly higher mHHS at most recent follow-up or mean improvement from baseline in Hip Outcome Score-Activities of Daily Living (p < 0.05). Three studies reported on HA, which was utilized exclusively in the nonoperative setting.

CONCLUSIONS

Intraoperative PRP and CBT have been commonly reported in the setting of hip arthroscopy for labral repairs and acetabular chondral lesions, respectively. The CBT cohorts demonstrated more favorable PROM at most recent follow-up when compared to a control group, though these results should be interpreted with caution due to heterogeneity of orthobiologic preparations.

LEVEL OF EVIDENCE

IV.

Equine Platelet-Rich Plasma

Platelet-rich plasma (PRP) is an orthobiologic therapy composed of platelets, leukocytes, red blood cells, and plasma proteins. PRP has been used for 20 years, but progress determining efficacy has been slow. The definitions and classification of PRP are reviewed, and the use of PRP for tendon, ligament, and joint disease is discussed with a focus on findings of basic science and clinical studies, platelet activation, concurrent administration of nonsteroidal anti-inflammatory drugs, and treatment complications. Finally, the advantages of platelet lysates and freeze-dried platelets are discussed. The promising results of a PRP lysate optimized for antibiofilm and antimicrobial properties are introduced.

Platelet-rich plasma therapy for temporomandibular joint osteoarthritis: A randomized controlled trial

The study aimed to compare the efficacy of platelet-rich plasma (PRP) injections for the treatment of temporomandibular joint osteoarthritis (TMJ-OA) with hyaluronic acid (HA) therapy. This randomized controlled trial included 70 patients with TMJ-OA, randomly divided into either a PRP or HA group. The pain intensity, maximum mouth opening (MMO), TMJ sound score, and proportion of crepitus were recorded and compared at baseline and at 1, 3, and 6 months. Both groups showed statistically significant improvements in pain intensity, MMO, TMJ sound, and scale scores during the 6-month follow-up period. The improvements in pain intensity during mouth opening at 1 month, MMO at 1, 3, and 6 months, TMJ sound score at 1 and 3 months, and GAD-7 score at 6 months in the PRP group were greater than in the HA group (p < 0.05). Compared with the HA group, imaging improvement in the PRP group was also higher (p < 0.05). Within the limitations of the study it seems that the application of PRP therapy in TMJ-OA is should be considered whenever possible.

Latest insights in disease-modifying osteoarthritis drugs development

Osteoarthritis (OA) is a prevalent and severely debilitating disease with an unmet medical need. In order to alleviate OA symptoms or prevent structural progression of OA, new drugs, particularly disease-modifying osteoarthritis drugs (DMOADs), are required. Several drugs have been reported to attenuate cartilage loss or reduce subchondral bone lesions in OA and thus potentially be DMOADs. Most biologics (including interleukin-1 (IL-1) and tumor necrosis factor (TNF) inhibitors), sprifermin, and bisphosphonates failed to yield satisfactory results when treating OA. OA clinical heterogeneity is one of the primary reasons for the failure of these clinical trials, which can require different therapeutic approaches based on different phenotypes. This review describes the latest insights into the development of DMOADs. We summarize in this review the efficacy and safety profiles of various DMOADs targeting cartilage, synovitis, and subchondral bone endotypes in phase 2 and 3 clinical trials. To conclude, we summarize the reasons for clinical trial failures in OA and suggest possible solutions.

Action of Platelet-Rich Plasma on In Vitro Cellular Bioactivity: More than Platelets

Platelet-rich plasma (PRP) is a biological therapy in which one of the mechanisms of action is the stimulation of biological processes such as cell proliferation. The size of PRP’s effect depends on multiple factors, one of the most important being the composition of PRP. The aim of this study was to analyze the relationship between cell proliferation and the levels of certain growth factors (IGF-1, HGF, PDGF, TGF-β and VEG) in PRP. First, the composition and effect on cell proliferation of PRP versus platelet-poor plasma (PPP) were compared. Subsequently, the correlation between each growth factor of PRP and cell proliferation was evaluated. Cell proliferation was higher in cells incubated with lysates derived from PRP compared to those cultured with lysates derived from PPP. In terms of composition, the levels of PDGF, TGF-β, and VEGF were significantly higher in PRP. When analyzing the PRP growth factors, IGF-1 was the only factor that correlated significantly with cell proliferation. Of those analyzed, the level of IGF-1 was the only one that did not correlate with platelet levels. The magnitude of PRP’s effect depends not only on platelet count but also on other platelet-independent molecules.

Efficacy of intra-articular injection of allogeneic platelet-rich plasma for knee osteoarthritis combined with hematologic blood dyscrasias with platelet dysfunction: protocol of a randomized, double-blind, placebo-controlled trial

BACKGROUND

Autologous platelet-rich plasma (PRP) has been shown to alleviate the symptoms of patients suffering from knee osteoarthritis (KOA), but for certain patients with hematologic diseases with platelet dysfunction and patients receiving anti-platelet medications, autologous PRP is not an optimum solution. Allogeneic PRP has been proven to be safe and effective in the treatment of osteoarthritis, rotator cuff disease, refractory wounds and other medical fields. However, a well-designed and long-term follow-up prospective randomized controlled trial (RCT) to evaluate the effect of allogeneic PRP intra-articular injections for KOA combined with hematologic blood dyscrasias has not yet been performed.

METHODS/ DESIGN

We will conduct an allogeneic PRP injection for KOA combined with hematologic blood dyscrasias with platelet dysfunction study: a prospective, randomized, double-blind, placebo-controlled trial. One hundred participants with KOA combined with hematologic blood dyscrasias with platelet dysfunction will be randomly allocated to receive either one allogeneic PRP injection or one saline injection into the knee joint. The primary outcome will be a 12-month change in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. Secondary outcomes will be the 36-Item Short-Form General Health Survey (SF-36) score, Lysholm score, overall knee pain score and MRI assessment at 1-, 3-, 6- and 12-month.

DISCUSSION

The results of this study will help determine whether allogeneic PRP could be used as a non-surgical intervention to treat patients with knee OA combined with hematologic blood dyscrasias with platelet dysfunction.

TRIAL REGISTRATION

Chinese Clinical Trials Registry reference: ChiCTR2100048624. Prospectively registered 11th of July 2021.

Limited evidence of adjuvant biologics with bone marrow stimulation for the treatment of osteochondral lesion of the talus: a systematic review

PURPOSE

To evaluate the complication rates, continuous functional outcome scores, and return to play data following bone marrow stimulation (BMS) versus biologics ± BMS for the treatment of osteochondral lesion of the talus (OLT).

METHODS

A systematic review was performed. The PubMed and Embase databases were searched using specific search terms and eligibility criteria according to the PRISMA guidelines. The level of evidence was assessed using published criteria by The Journal of Bone & Joint Surgery, and the quality of evidence using the Modified Coleman Methodology Score. Continuous variables were presented as mean ± standard deviation and categorical variables as frequencies (percentages).

RESULTS

BMS versus BMS + hyaluronic acid (HA): no complications in either treatment arm were reported. The mean American Orthopaedic Foot and Ankle Society score was 43.5 to 67.3 points and 44.0 to 72.4 points, respectively. The mean 10 mm Visual Analogue Scale pain score was 7.7 to 3.8 points and 7.5 to 2.5 points, respectively. BMS versus BMS + concentrated bone marrow aspirate (CBMA): the pooled overall complication rate was 17/64 (26.6%) versus 11/71 (15.5%), respectively (non-significant). The pool revision rate was 15/64 (23.4%) versus 6/71 (8.5%), respectively (p = 0.016). There has been a notable poor reporting of complication rates for the use of ADSC and PRP as adjuvant biological therapies to BMS for the treatment of OLT.

CONCLUSION

There was an overall limited comparative clinical evidence of adjuvant biologics with BMS versus BMS alone for the treatment of OLT. BMS + HA and BMS + CBMA can provide superior outcomes, albeit the currently limited evidence. Further studies are warranted to establish the true clinical superiority of the various biologics ± BMS versus BMS alone. These studies must also compare the various biologics against one another to determine, if any, the optimal biologic for OLT. Clinicians should counsel patients accordingly on these findings as required.

LEVEL OF EVIDENCE

Level III.

Bone marrow aspirate injection for osteoarthritis of the hip; A pilot study

Objectives

Bone marrow aspirate (BMA) intra-articular injection is a minimally invasive orthobiologic treatment option for osteoarthritis (OA). Hip OA affects a significant portion of the population and has a paucity of data surrounding orthobiologic treatments. The primary objective of this study was to delineate the clinical impact of bone marrow aspirate intra-articular injections on decreasing pain and improving function in patients with hip OA.

Methods

A single-center, retrospective analysis of thirty-one patients, aged 32 to 83 (62.4 ​± ​16.5), with Kellgren-Lawrence (KL) Hip OA grading of 2-4 (mean 2.9 ​± ​0.7), who underwent intra-articular bone marrow aspirate injection into the hip and were followed for twelve months. Evaluation was at baseline, 12 weeks, 6 months, and 12 months using the Numerical Rating Scale (NRS) for pain and the Hip Disability and Osteoarthritis Outcome Score Jr (HOOS-Jr) for function. The proportion of responders, as defined by a ≥50% reduction in NRS pain score, was assessed at 12 weeks, 6 months and 12 months.

Results

At 6 and 12 months follow-up, there was a statistically significant improvement in NRS scores (P ​< ​0.05). Stratifying by KL grade, subjects with KL grades 2 and 3 experienced statistically significant improvement in NRS scores at 6 and 12 months. Patients with KL grade 4 showed significant improvement in pain at 12 months. Forty-two percent of patients at 6 months and 61% at 12 months reported ≥50% reduction in pain. When stratifying by KL grade, 80% and 71% of KL2 and KL3 grades respectively were responders by 12 months. Patients experienced statistically significant improvement in HOOS-Jr scores at 6 and 12 months.

Conclusion

In patient with mild, moderate, and severe hip OA, BMA may be an alternative treatment that improves pain and function in patients for as long as 12 months. In addition, BMA may also be an effective, lower cost option to more expensive BMAC preparations.

Improved biological performance of human cartilage-derived progenitors in platelet lysate xenofree media in comparison to fetal bovine serum media

Primary articular cartilage-derived cells are among the preferred contenders for cell-based therapy approaches for cartilage repair. Limited access to primary human cartilage tissue necessitates the process of in vitro cell expansion to obtain sufficient cells for therapeutic purposes. Therapeutic outcomes of such cell-based approaches become highly dependent on the quality of the in vitro culture-expanded cells. The objective of this study was to determine the differential biological effects of human platelet lysate (hPL) xeno-free defined media vs FBS containing traditional media on primary human cartilage-derived cells. Our goal in pursuing this work was to identify a preferred xenofree media alternative, that can be used as a platform for expansion of cells intended for clinical applications. Primary cartilage-derived cells obtained from five patients were simultaneously cultured in two expansion media's: (1) traditional (DMEM+10%FBS+1%P/S) and (2) defined xenofree (Nutristem® complete media+0.5%hPL). Connective tissue progenitors (CTPs) were assayed by standard colony forming unit assay, morphology, proliferation in early and late passages, expression of MSC associated cell-surface markers (CD73, CD90 and CD105) and trilineage differentiation (adipogenesis, osteogenesis and chondrogenesis) were considered for comparison of biological performance. Early biological performance of primary cartilage-derived cells was significantly improved in Nutristem® expansion media in comparison to traditional expansion media with respect to (1) Colony forming efficiency tended to be higher (p = 0.058) and (2) CTPs formed larger colonies with respect to total cells per colony and colony area (p < 0.01). In the culture expanded cell population, Nutristem® expansion media was superior to traditional expansion media with respect to: (1) overall proliferation rate through passages 1-4 (p = 0.027), (2) total cells harvested at end of passage 4 (p = 0.028) and (3) total positive stain area of CD73 (p = 0.006), CD90 (p = 0.001) and CD105 (p = 0.049). Nutristem®-hPL expanded cells when differentiated in respective xenofree serum-free defined MSCgo™ differentiated media's, also showed significant improvement in adipogenic, osteogenic and chondrogenic marker expression. Overall, we convincingly demonstrated that a low concentration of hPL in combination with defined xenofree media is an effective and economic growth supplement to culture expand primary cartilage-derived cells. It can be manufactured under cGMP conditions to improve clinical-grade cell products' quality for therapeutic applications.

Time to Total Knee Arthroplasty after Intra-Articular Hyaluronic Acid or Platelet-Rich Plasma Injections: A Systematic Literature Review and Meta-Analysis

Intra-articular (IA) hyaluronic acid (HA) and platelet-rich plasma (PRP) injections are increasingly being prescribed for knee osteoarthritis (KOA). However, failure of the medical treatment may result in total knee arthroplasty (TKA). We wondered if IA HA or PRP injections (intervention) may delay the time to TKA (outcome) among KOA patients (population), compared to KOA patients not receiving these injections (comparator). For this systematic literature review (SLR) and meta-analysis, we selected observational studies with at least one group of patients receiving IA HA or PRP and with TKA data available. The main outcome was time from the diagnosis of KOA to TKA. We included 25 articles in the SLR (2,824,401 patients) and four in the meta-analysis. The mean strengthening the reporting of observational studies in epidemiology (STROBE) score was 63%. For patients receiving versus not receiving HA injections, the delay between a declared diagnosis of KOA to TKA was increased by 9.8 months (95% CI (8.2-11.4)). As compared with standard of care, the effect size of HA injections for this outcome was 0.57 (95% CI (0.36-0.76)). Only one study described a median time from PRP injections to TKA of 4.1 years (range 0.3-14.7). IA HA injections were associated with increased time to TKA. Causality cannot be concluded because of missing confounder factors as comorbidities. Data were insufficient to conclude any effect of PRP injections on TKA delay.

Progress of Platelet Derivatives for Cartilage Tissue Engineering

Articular cartilage has limited self-regeneration ability for lacking of blood vessels, nerves, and lymph that makes it a great challenge to repair defects of the tissue and restore motor functions of the injured or aging population. Platelet derivatives, such as platelet-rich plasma, have been proved effective, safe, and economical in musculoskeletal diseases for their autologous origin and rich in growth factors. The combination of platelet derivatives with biomaterials provides both mechanical support and localized sustained release of bioactive molecules in cartilage tissue engineering and low-cost efficient approaches of potential treatment. In this review, we first provide an overview of platelet derivatives and their application in clinical and experimental therapies, and then we further discuss the techniques of the addition of platelet derivatives and their influences on scaffold properties. Advances in cartilage tissue engineering with platelet derivatives as signal factors and structural components are also introduced before prospects and concerns in this research field. In short, platelet derivatives have broad application prospects as an economical and effective enhancement for tissue engineering–based articular cartilage repair.

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.

Effects of leukocyte-rich platelet-rich plasma and leukocyte-poor platelet-rich plasma on the healing of bone-tendon interface of rotator cuff in a mice model

Platelet-rich plasma (PRP) is widely used clinically to treat tendon injuries, and often contains leukocytes. However, the debate regarding the concentration of leukocytes in PRP is still ongoing. This study aimed to evaluate the therapeutic effects of leukocyte-rich platelet-rich plasma (LR-PRP) and leukocyte-poor platelet-rich plasma (LP-PRP) on the healing of the bone-tendon interface (BTI) of the rotator cuff. A total of 102 C57BL/6 mice were used. Thirty mice were used to prepare the PRP, while 72 underwent acute supraspinatus tendon injury repair. The animals were then randomly assigned to three groups: LR-PRP, LP-PRP and control groups. The mice were euthanized at 4 and 8 weeks postoperatively, and histological, immunological and biomechanical analyses were performed. The histological results showed that the fusion effect at the bone-tendon interface at 4 and 8 weeks after surgery was greater in the PRP groups and significantly increased at 4 weeks; however, at 8 weeks, the area of the fibrocartilage layer in the LP-PRP group increased significantly. M2 macrophages were observed at the repaired insertion for all the groups at 4 weeks. At 8 weeks, M2 macrophages withdrew back to the tendon in the control group, but some M2 macrophages were retained at the repaired site in the LR-PRP and LP-PRP groups. Enzyme-linked immunoassay results showed that the concentrations of IL-1β and TNF-α in the LR-PRP group were significantly higher than those in the other groups at 4 and 8 weeks, while the concentrations of IL-1β and TNF-α in the LP-PRP group were significantly lower than those in the control group. The biomechanical properties of the BTI were significantly improved in the PRP group. Significantly higher failure load and ultimate strength were seen in the LR-PRP and LP-PRP groups than in the control group at 4 and 8 weeks postoperatively. Thus, LR-RPR can effectively enhance the early stage of bone-tendon interface healing after rotator cuff repair, and LP-PRP could enhance the later stages of healing after rotator cuff injury.

Platelet-Rich Plasma Does Not Inhibit Inflammation or Promote Regeneration in Human Osteoarthritic Chondrocytes In Vitro Despite Increased Proliferation

OBJECTIVE

The aims of the study were to assess the anti-inflammatory properties of platelet-rich plasma (PRP) and investigate its regenerative potential in osteoarthritic (OA) human chondrocytes. We hypothesized that PRP can modulate the inflammatory response and stimulate cartilage regeneration.

DESIGN

Primary human chondrocytes from OA knees were treated with manually prepared PRP, after which cell migration and proliferation were assessed. Next, tumor necrosis factor-α-stimulated chondrocytes were treated with a range of concentrations of PRP. Expression of genes involved in inflammation and chondrogenesis was determined by real-time polymerase chain reaction. In addition, chondrocytes were cultured in PRP gels and fibrin gels consisting of increasing concentrations of PRP. The production of cartilage extracellular matrix (ECM) was assessed. Deposition and release of glycosaminoglycans (GAG) and collagen was quantitatively determined and visualized by (immuno)histochemistry. Proliferation was assessed by quantitative measurement of DNA.

RESULTS

Both migration and the inflammatory response were altered by PRP, while proliferation was stimulated. Expression of chondrogenic markers COL2A1 and ACAN was downregulated by PRP, independent of PRP concentration. Chondrocytes cultured in PRP gel for 28 days proliferated significantly more when compared with chondrocytes cultured in fibrin gels. This effect was dose dependent. Significantly less GAGs and collagen were produced by chondrocytes cultured in PRP gels when compared with fibrin gels. This was qualitatively confirmed by histology.

CONCLUSIONS

PRP stimulated chondrocyte proliferation, but not migration. Also, production of cartilage ECM was strongly downregulated by PRP. Furthermore, PRP did not act anti-inflammatory on chondrocytes in an in vitro inflammation model.

Microfracture for the Treatment of Symptomatic Cartilage Lesions of the Knee: A Survey of International Cartilage Regeneration & Joint Preservation Society

OBJECTIVE

The purpose of this study was to describe the current practice trends for managing symptomatic cartilage lesions of the knee with microfracture among ICRS (International Cartilage Regeneration & Joint Repair Society) members.

DESIGN

A 42-item electronic questionnaire was sent to all ICRS members, which explored indications, surgical technique, postoperative management, and outcomes of the microfracture procedure for the treatment of symptomatic, full thickness chondral and osteochondral defects of the knee. Responses were compared between surgeons from different regions and years of practice.

RESULTS

A total of 385 surgeons answered the questionnaire. There was a significant difference noted in the use of microfracture among surgeons by region (P < 0.001). There was no association between the number of years in practice and the self-reported proportion of microfracture cases performed (P = 0.37). Fifty-eight subjects (15%) indicated that they do not perform microfracture at all. Regarding indication for surgery, 56% of surgeons would limit their indication of microfracture to lesions measuring 2 cm² or less. Half of the surgeons reported no upper age or body mass index limit. Regarding surgical technique, 90% of surgeons would recommend a formal debridement of the calcified layer and 91% believe it is important to create stable vertical walls. Overall, 47% of surgeons use biologic augmentation, with no significant difference between regions (P = 0.35) or years of practice (P = 0.67). Rehabilitation protocols varied widely among surgeons.

CONCLUSIONS

Indications, operative technique, and rehabilitation protocols utilized for patients undergoing microfracture procedures vary widely among ICRS members. Regional differences and resources likely contribute to these practice pattern variations.

Effect of Intra-articular Platelet-Rich Plasma vs Placebo Injection on Pain and Medial Tibial Cartilage Volume in Patients With Knee Osteoarthritis: The RESTORE Randomized Clinical Trial

IMPORTANCE

Most clinical guidelines do not recommend platelet-rich plasma (PRP) for knee osteoarthritis (OA) because of lack of high-quality evidence on efficacy for symptoms and joint structure, but the guidelines emphasize the need for rigorous studies. Despite this, use of PRP in knee OA is increasing.

OBJECTIVE

To evaluate the effects of intra-articular PRP injections on symptoms and joint structure in patients with symptomatic mild to moderate radiographic medial knee OA.

DESIGN, SETTING, AND PARTICIPANTS

This randomized, 2-group, placebo-controlled, participant-, injector-, and assessor-blinded clinical trial enrolled community-based participants (n = 288) aged 50 years or older with symptomatic medial knee OA (Kellgren and Lawrence grade 2 or 3) in Sydney and Melbourne, Australia, from August 24, 2017, to July 5, 2019. The 12-month follow-up was completed on July 22, 2020.

INTERVENTIONS

Interventions involved 3 intra-articular injections at weekly intervals of either leukocyte-poor PRP using a commercially available product (n = 144 participants) or saline placebo (n = 144 participants).

MAIN OUTCOMES AND MEASURES

The 2 primary outcomes were 12-month change in overall average knee pain scores (11-point scale; range, 0-10, with higher scores indicating worse pain; minimum clinically important difference of 1.8) and percentage change in medial tibial cartilage volume as assessed by magnetic resonance imaging (MRI). Thirty-one secondary outcomes (25 symptom related and 6 MRI assessed; minimum clinically important difference not known) evaluated pain, function, quality of life, global change, and joint structures at 2-month and/or 12-month follow-up.

RESULTS

Among 288 patients who were randomized (mean age, 61.9 [SD, 6.5] years; 169 [59%] women), 269 (93%) completed the trial. In both groups, 140 participants (97%) received all 3 injections. After 12 months, treatment with PRP vs placebo injection resulted in a mean change in knee pain scores of -2.1 vs -1.8 points, respectively (difference, -0.4 [95% CI, -0.9 to 0.2] points; P = .17). The mean change in medial tibial cartilage volume was -1.4% vs -1.2%, respectively (difference, -0.2% [95% CI, -1.9% to 1.5%]; P = .81). Of 31 prespecified secondary outcomes, 29 showed no significant between-group differences.

CONCLUSIONS AND RELEVANCE

Among patients with symptomatic mild to moderate radiographic knee OA, intra-articular injection of PRP, compared with injection of saline placebo, did not result in a significant difference in symptoms or joint structure at 12 months. These findings do not support use of PRP for the management of knee OA.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry Identifier: ACTRN12617000853347.

American Medical Society for Sports Medicine Position Statement: Principles for the Responsible Use of Regenerative Medicine in Sports Medicine

ABSTRACT

Many sports medicine physicians are currently considering introducing regenerative medicine into their practice. Regenerative medicine and the subclassification of orthobiologics are a complicated topic and have produced widely varying opinions. Although there is concern by government regulators, clinicians, scientists, patient advocacy organizations, and the media regarding the use of regenerative medicine products, there is also excitement about the potential benefits with growing evidence that certain regenerative medicine products are safe and potentially efficacious in treating musculoskeletal conditions. Sports medicine physicians would benefit from decision-making guidance about whether to introduce orthobiologics into their practice and how to do it responsibly. The purpose of this position statement is to provide sports medicine physicians with information regarding regenerative medicine terminology, a brief review of basic science and clinical studies within the subclassification of orthobiologics, regulatory considerations, and best practices for introducing regenerative medicine into clinical practice. This information will help sports medicine physicians make informed and responsible decisions about the role of regenerative medicine and orthobiologics in their practice.

Supercritical carbon dioxide decellularized porcine cartilage graft with PRP attenuated OA progression and regenerated articular cartilage in ACLT-induced OA rats

Knee osteoarthritis (OA) is a common degenerative articular disorder and considered one of the primary causes of pain and functional disability. Knee OA is prevalent in 10% of men and 13% of women aged 60 years above. The study aims to use cartilage tissue engineering that combines the triads of decellularized porcine cartilage graft as "scaffold," plasma rich platelet (PRP) as "signal" and chondrocytes from rat as "cell" to attenuate ACLT-induced OA progression and regenerate the knee cartilage in rats. Decellularization of the porcine cartilage was characterized by hematoxylin and eosin, 4,6-Diamidino-2-phenylindole staining, scanning electron microscopy and residual DNA quantification. The protective effect of decellularized porcine cartilage graft (dPCG) was evaluated by intra-articular administration in surgically induced anterior cruciate ligament transection (ACLT) rat osteoarthritis (OA) model. Supercritical carbon dioxide technology completely decellularized the porcine cartilage. Intra-articular administration of dPCG with or without PRP significantly reduced the ACLT-induced OA symptoms and attenuated the OA progression. Pain-relief by dPCG with or without PRP was assessed by capacitance meter and improved articular cartilage damage in the rat knee was characterized by X-ray and micro-CT. Besides, the histological analysis depicted cartilage protection by dPCG with or without PRP. The repairation and attenuation effect by dPCG with or without PRP in the articular knee cartilage damage were also explored by safranin-O, type II collagen, aggrecan and SOX-9 immuno-staining. To conclude, intra-articular administration of dPCG with or without PRP is efficient in repairing the damaged cartilage in the experimental OA model.

Characterization and Therapeutic Use of Extracellular Vesicles Derived from Platelets

Autologous blood products, such as platelet-rich plasma (PRP), are gaining increasing interest in different fields of regenerative medicine. Although growth factors, the main components of PRP, are thought to stimulate reparation processes, the exact mechanism of action and main effectors of PRP are not fully understood. Plasma contains a high amount of extracellular vesicles (EVs) produced by different cells, including anucleated platelets. Platelet-derived EVs (PL-EVs) are the most abundant type of EVs in circulation. Numerous advantages of PL-EVs, including their ability to be released locally, their ease of travel through the body, their low immunogenicity and tumourigenicity, the modulation of signal transduction as well as the ease with which they can be obtained, has attracted increased attention n. This review focuses briefly on the biological characteristics and isolation methods of PL-EVs, including exosomes derived from platelets (PL-EXOs), and their involvement in the pathology of diseases. Evidence that shows how PL-EVs can be used as a novel tool in medicine, particularly in therapeutic and regenerative medicine, is also discussed in this review.

The 2020 NBA Orthobiologics Consensus Statement

This 2020 NBA Orthobiologics Consensus Statement provides a concise summary of available literature and practical clinical guidelines for team physicians and players. We recognize that orthobiologic injections are a generally safe treatment modality with a significant potential to reduce pain and expedite early return to play in specific musculoskeletal injuries. The use of orthobiologics in sports medicine to safely reduce time loss and reinjury is of considerable interest, especially as it relates to the potential effect on a professional athlete. While these novel substances have potential to enhance healing and regeneration of injured tissues, there is a lack of robust data to support their regular use at this time. There are no absolutes when considering the implementation of orthobiologics, and unbiased clinical judgment with an emphasis on player safety should always prevail. Current best evidence supports the following: Key Points There is support for the use of leukocyte-poor platelet-rich plasma in the treatment of knee osteoarthritis. There is support for consideration of using leukocyte-rich platelet-rich plasma for patellar tendinopathy. The efficacy of using mesenchymal stromal cell injections in the management of joint and soft tissue injuries remains unproven at this time. There are very few data to suggest that current cell therapy treatments lead to any true functional tissue regeneration. Meticulous and sterile preparation guidelines must be followed to minimize the risk for infection and adverse events if these treatments are pursued.Given the high variability in orthobiologic formulations, team physicians must stay up-to-date with the most recent peer-reviewed literature and orthobiologic preparation protocols for specific injuries.Evidence-based treatment algorithms are necessary to identify the optimal orthobiologic formulations for specific tissues and injuries in athletes.Changes in the regulatory environment and improved standardization are required given the exponential increase in utilization as novel techniques and substances are introduced into clinical practice.

Platelet-Rich Plasma Combined With Hyaluronic Acid Improves Pain and Function Compared With Hyaluronic Acid Alone in Knee Osteoarthritis: A Systematic Review and Meta-analysis

PURPOSE

To evaluate the efficacy of platelet-rich plasma (PRP) combined with hyaluronic acid (HA) injections versus HA injections alone for the management of knee osteoarthritis (OA).

METHODS

This study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eligible randomized-controlled trials and observational studies directly comparing combined PRP-HA injections with HA injections alone were identified through a search of PubMed, Scopus, and Cochrane Central databases from inception to May 2020. A random effects model meta-analysis was conducted and the I² statistic was used to assess for heterogeneity.

RESULTS

Four studies comprising 377 patients (PRP-HA: 193, HA: 184) with knee OA ranging from I-IV Kellgren-Lawrence grading scale were included. The final follow-up was 12 months in 3 studies and 6 months in 1 study. Patients who received PRP combined with HA had significantly greater improvements compared with those injected with HA alone in terms of visual analog scale scores at 3-month (standardized mean difference [SMD] 1.13; 95% confidence interval [CI] 0.56-1.70; I² = 56.7%; P < .001), 6-month (SMD 1.08; 95% CI 0.54-1.62; I² = 67.9%; P < .001), and 12-month (SMD 1.13; 95% CI 0.74-1.52; I² = 0.0%; P < .001) and 12-month Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical functioning (SMD 0.91; 95% CI 0.65-1.17; I² = 0.0%; P < .001) and 12-month WOMAC stiffness (SMD 1.09; 95% CI 0.80-1.38; I² = 0.0%; P < .001) scores. No difference was identified in terms of 12-month WOMAC pain score (SMD 0.36; 95% CI -0.19 to 0.91; I² = 74.1%; P = .195).

CONCLUSIONS

Symptomatic patients with knee OA who were injected with a combination of PRP and HA demonstrated greater improvement in pain and function compared with patients who received HA injections only, as assessed by 3-, 6-, and 12-month visual analog scale scores and 12-month WOMAC physical function and stiffness scores. This study provides encouraging evidence for the use of the combined PRP-HA injections in the management of symptomatic patients with knee OA.

LEVEL OF EVIDENCE

III (meta-analysis of randomized and non-randomized comparative trials).

Glenohumeral Osteoarthritis: The Role for Orthobiologic Therapies: Platelet-Rich Plasma and Cell Therapies

The glenohumeral (GH) joint ranks third on the list of the large joints that are most commonly affected by osteoarthritis, after the knee and the hip. General nonsurgical modalities, including changes in daily activities, physical therapy, pharmacotherapy, and corticosteroid injections, constitute the mainstay of treatment. Most of these options, however, have shown moderate and short-term effectiveness. Arthroplasty techniques have proven to be successful for elderly patients. Nevertheless, replacement options are not optimal for younger patients because their functional demands are higher and prostheses have a finite life span. This has led to the search for new nonoperative treatment options to target this subgroup of patients. It has been suggested that orthobiologic therapies, including platelet-rich plasma (PRP) and cell therapies, present great promise and opportunity for the treatment of GH osteoarthritis. Despite the promising results that have been shown by cell therapies and PRP for treating degenerative joint conditions, additional studies are needed to provide more definitive conclusions.

Systemic effects of platelet-rich plasma local injection on serum and urinary anabolic metabolites: A prospective randomized study

Platelet-rich plasma (PRP) is widely utilized in the treatment of sports injuries. However, potential systemic effects after localized PRP injection are unclear at present. In this prospective randomized study, 24 Taiwanese male athletes with tendinopathy were randomized into a PRP group (n = 13) or a saline group (n = 11). The concentrations of serum and urine biomarkers were quantified by enzyme-linked immunosorbent assay assessment as well as gas chromatographic and mass spectrometric analysis, respectively. The results showed no significant differences in serum levels of growth hormone, insulin-like growth factor-1, insulin-like growth factor-binding protein 3, vascular endothelial growth factor, platelet-derived growth factor-BB, or serum substance P(SP) between the two groups before intervention, nor at 1, 2, or 7 days after intervention. However, a significant decrease in the serum SP level 1 and 7 days after PRP injection was observed. Regarding urinary concentrations of metabolites of anabolic androgenic steroids (AAS), no between-group differences before intervention, nor at 1, 2, or 7 days after intervention, were observed. Our study failed to observe significant surge of serum anabolic molecules and urinary excretion of anabolic AAS metabolites after PRP injection.

Effects of platelet-rich plasma injection for pain control and cartilage repair in knee osteoarthritis: A protocol for the systematic review and meta-analysis of randomized controlled trials in animal models

BACKGROUND

Knee osteoarthritis (KOA) is a common disabling condition and a heavy financial burden to the society. Platelet-rich plasma (PRP) is considered to be an effective method in the repair and regeneration of cartilage and alleviate pain in KOA. But the utilising of PRP to treat KOA in clinical has shown variable results from many studies. The objective of this protocol is to determine the efficacy of PRP in pain control and cartilage repair in KOA animal models.

METHOD

We will search the following three electronic databases: MEDLINE, EMBASE and Web of Science. The primary outcome will include the histological score of cartilage and pain score. The secondary outcomes will be the behavioural assessments and cartilage thickness. SYRCLE's risk of bias tool will be used to assessment the risk of bias of including studies. The standardized mean difference and 95% confidence interval will be used to calculate the effect of PRP treatment. The I2 inconsistency values will be used to calculated the heterogeneity between studies.

RESULTS

The results of this paper will be submitted to a peer-reviewed journal for publication.

CONCLUSION

This research will determine the efficacy of PRP of the treatment of knee osteoarthritis model.

PROSPERO REGISTRATION NUMBER

CRD42020181589.

Intra-articular injections of platelet-rich plasma in symptomatic knee osteoarthritis: a consensus statement from French-speaking experts

PURPOSE

There has been much debate regarding the use of intra-articular injections of platelet-rich plasma (PRP) as symptomatic treatment for knee osteoarthritis. The objective of this consensus was to develop guidelines for PRP injections in knee osteoarthritis according to the French National Authority for Health recommendations.

METHODS

Fifteen physicians from different French-speaking countries (10 rheumatologists, 4 specialists in rehabilitation and sports medicine and 1 radiologist) were selected for their expertise in the areas of PRP and osteoarthritis. A comprehensive literature review was conducted on Medline including all published therapeutic trials, open studies, meta-analysis and systematic reviews focusing on the effects of PRP in knee OA, as well as fundamental studies concerning the characteristics of the various types of PRP and their mechanisms, indexed before April 2019. Using the method recommended by the French National Authority for Health inspired by the Delphi consensus process, 25 recommendations were finally retained and evaluated. The recommendations were classified as appropriate or not appropriate, with strong or relative agreement, or uncertain if a consensus was not achieved.

RESULTS

Among the 25 recommendations selected, the main ones are the following: (1) Intra-articular injections of PRP are an effective symptomatic treatment for early to moderate knee osteoarthritis. This recommendation was considered appropriate with a relative agreement (Median = 8; rank = 6-9). Level of evidence 1A. (2) A PRP treatment sequence in knee osteoarthritis may include 1-3 injections. This recommendation was considered appropriate with a strong agreement (Median = 9; rank = 7-9). Level of evidence 1A. (3) Leucocytes-poor PRP should be preferred in knee osteoarthritis. This recommendation was considered appropriate with a relative agreement (Median = 8; rank = 5-9). Level of evidence 5. (4) Intra-articular PRP knee injections should be performed under ultrasound or fluoroscopic guidance. This recommendation was considered uncertain with no consensus (Median = 8; rank = 3-9). Level of evidence 5. (5) PRP should not be mixed with an anesthetic or intra-articular corticosteroid. This recommendation was considered appropriate with a relative agreement (Median = 9; rank = 6-9). Level of evidence 5 CONCLUSION: Those 25 recommendations should standardize and facilitate the use of IA PRP injections, which are considered by experts as an effective treatment especially in early or moderate knee OA. Although a strong or relative agreement from the experts was obtained for most of the recommendations, many of them had a very low level of evidence (Level 5) and were principally based on the clinical experience of the experts.

3D composite engineered using supercritical CO2 decellularized porcine cartilage scaffold, chondrocytes, and PRP: Role in articular cartilage regeneration

At present, no definitive treatment for articular cartilage defects has been perfected. Most of the previous treatments involved multiple drilling and microfracture over defect sites with repair-related substances, which poses a limited therapeutic effect. End-stage therapy includes artificial knee joint replacement. In this study, we prepared a novel decellularized natural cartilage scaffold from porcine articular cartilage by supercritical CO₂ extraction technology and three-dimensional (3D) composites made using decellularized porcine cartilage graft (dPCG) as scaffolds, platelet-rich plasma (PRP), thrombin as signals and chondrocytes as cells for the treatment of articular cartilage defects. In this study, in vitro and in vivo cartilage regeneration and the expression of chondrogenic markers were examined. Decellularized cartilage graft (dPCG) was evaluated for the extent of cell and DNA removal. Residual cartilage ECM structure was confirmed to be type II collagen by SDS PAGE and immunostaining. The new 3D composite with dPCG (100 mg and 2 × 10⁶ chondrocytes) scaffold promotes chondrogenic marker expression in vitro. We found that the in vivo 3D composite implanted cartilage defect showed significant regeneration relative to the blank and control implant. Immunohistochemical staining showed increase of expression including Collagen type II and aggrecan in 3D composite both in vitro and in vivo studies. In this study, the bioengineered 3D composite by combining dPCG scaffold, chondrocytes, and PRP facilitated the chondrogenic marker expression in both in vitro and in vivo models with accelerated cartilage regeneration. This might serve the purpose of clinical treatment of large focal articular cartilage defects in humans in the near future.

Intra-articular injection with Autologous Conditioned Plasma does not lead to a clinically relevant improvement of knee osteoarthritis: a prospective case series of 140 patients with 1-year follow-up

Background and purpose - Platelet-rich plasma (PRP) is broadly used in the treatment of knee osteoarthritis, but clinical outcomes are highly variable. We evaluated the effectiveness of intra-articular injections with Autologous Conditioned Plasma (ACP), a commercially available form of platelet-rich plasma, in a tertiary referral center. Second, we aimed to identify which patient factors are associated with clinical outcome. Patients and methods - 140 patients (158 knees) with knee osteoarthritis (Kellgren and Lawrence grade 0-4) were treated with 3 intra-articular injections of ACP. The Knee Injury and Osteoarthritis Outcome Score (KOOS), pain (Numeric Rating Scale; NRS), and general health (EuroQol 5 Dimensions; EQ5D) were assessed at baseline and 3, 6, and 12 months' follow-up. The effect of sex, age, BMI, Kellgren and Lawrence grade, history of knee trauma, and baseline KOOS on clinical outcome at 6 and 12 months was determined using linear regression. Results - Mean KOOS increased from 37 at baseline to 44 at 3 months, 45 at 6 months, and 43 at 12 months' follow-up. Mean NRS-pain decreased from 6.2 at baseline to 5.3 at 3 months, 5.2 at 6 months, and 5.3 at 12 months. EQ5D did not change significantly. There were no predictors of clinical outcome. Interpretation - ACP does not lead to a clinically relevant improvement (exceeding the minimal clinically important difference) in patients suffering from knee osteoarthritis. None of the investigated factors predicts clinical outcome.

Platelet-rich plasma for the treatment of adolescent late-stage femoral head necrosis: a case report

Osteonecrosis of femoral head (ONFH) is a disabling and intractable disease. Previous studies reported the increasing failure rates of total hip arthroplasty in younger patients, thus there should be special considerations for the adolescents. In this paper, we present a case of an adolescent female with late-stage glucocorticoid-induced ONFH (according to the Association Research Circulation Osseous classification system, Association Research Circulation Osseous IV). The patient received five consecutive ultrasound-guided intra-articular injections of platelet-rich plasma, and the therapeutic effects were assessed by visual analog scale, joint range of motion, Western Ontario and McMaster Universities Osteoarthritis Index, Harris Hip Score and magnetic resonance imaging. At 9-month follow-up, clinical and radiological reassessments demonstrated favorable outcomes. This case highlights the therapeutic potential of platelet-rich plasma injections for the late-stage ONFH, especially for adolescent patients.

Systematic Review and Meta-Analysis of Nonoperative Platelet-Rich Plasma Shoulder Injections for Rotator Cuff Pathology

BACKGROUND

Platelet-rich plasma (PRP) injections have been introduced to augment the recovery of patients with shoulder pathology. Although multiple studies have been published, no large-scale trials or meta-analyses have assessed the efficacy of nonoperative shoulder PRP injection.

OBJECTIVE

To assess the efficacy of nonoperative PRP shoulder injection in rotator cuff pathology for pain as measured by the visual analog scale (VAS) and range of motion (ROM).

DESIGN

Two authors independently screened the Medline and Cochrane databases to include prospective studies that reported VAS and ROM outcomes for nonoperative shoulder PRP injections for rotator cuff pathology. Study quality was assessed using the revised Cochrane Collaboration risk-of-bias tool and modified Downs and Black checklist. Subsequent meta-analysis was performed to determine the effect of nonoperative PRP injections on pain and ROM 3 to 12 months after intervention.

RESULTS

Six studies met systematic review criteria. The included studies used different PRP formulations (concentration, leukocyte count), injection protocols (approach, injection number), and varied study designs. Three studies concluded that PRP provided no significant benefit for pain and ROM when compared to physical therapy. Within-group meta-analysis of six fairly heterogeneous studies (I² 77.8%) demonstrated a statistically significant (P < .001) improvement in pain 3 to 12 months after PRP injection. Within-group meta-analysis for four studies for shoulder flexion and abduction was found to be too heterogeneous to derive meaningful results.

CONCLUSION

There is a limited quantity of high-quality studies that assess the efficacy of nonoperative PRP shoulder injection for pain and ROM. Systematic review of PRP injections did not demonstrate an improvement in pain or ROM compared to physical therapy. Although within-group meta-analysis of nonoperative PRP statistically showed that nonoperative PRP improved pain, the lack of adequate negative controls precludes the ability to conclude whether improvements were due to natural recovery or nonoperative PRP.

Leukocyte-dependent effects of platelet-rich plasma on cartilage loss and thermal hyperalgesia in a mouse model of post-traumatic osteoarthritis

OBJECTIVE

Platelet-rich plasma (PRP) is an emerging therapeutic strategy for treatment of osteoarthritis (OA); however, there is a lack of preclinical and clinical evidence for its efficacy and its mechanism of action is unclear. In the current study, we utilized leukocyte poor-PRP (LP-PRP) and leukocyte rich-PRP (LR-PRP) to mimic clinical point of care formulations and assessed their potential to alter disease progression in a mouse model of post-traumatic OA.

METHOD

Three-month-old wild-type male FVB/N mice received destabilization of the medial meniscus (DMM) surgery to induce OA. To assess the efficacy of LP-PRP and LR-PRP, mice were given intraarticular injections at 2-, 7- and 28-days post-surgery. Mice were then assessed at 5-, 9-, and 13-weeks post-surgery for changes in chronic pain using the hot plate nociceptive assay. At 14-weeks, OA pathogenesis was evaluated using histology and phase-contrast μCT.

RESULTS

Treatment with LP-PRP and to a lesser extent LR-PRP preserved cartilage volume and surface area compared to phosphate-buffered saline (PBS) as measured by phase-contrast μCT. However, both treatments had higher Osteoarthritis Research Society International (OARSI) and synovitis scores compared to sham, and neither substantially improved scores compared to PBS controls. With respect to thermal hyperalgesia, PBS-treated mice displayed reduced latency to response compared to sham, and LR-PRP but not LP-PRP improved latency to response at 5-, 9- and 13-weeks post-surgery compared to PBS.

CONCLUSION

The results of this study suggest that effects of PRP therapy on OA progression and disease-induced hyperalgesia may be leukocyte-dependent. And while LP-PRP and to a lesser extent LR-PRP protect from volume and surface loss, significant pathology is still seen within OA joints. Future work is needed to understand how the different components of PRP effect OA pathogenesis and pain, and how these could be modified to achieve greater therapeutic efficacy.

Characterization and Chondroprotective Effects of Extracellular Vesicles From Plasma- and Serum-Based Autologous Blood-Derived Products for Osteoarthritis Therapy

Autologous blood products gain increasing interest in the field of regenerative medicine as well as in orthopedics, aesthetic surgery, and cosmetics. Currently, citrate-anticoagulated platelet-rich plasma (CPRP) preparations are often applied in osteoarthritis (OA), but more physiological and cell-free alternatives such as hyperacute serum (hypACT) are under development. Besides growth factors, blood products also bring along extracellular vesicles (EVs) packed with signal molecules, which open up a new level of complexity at evaluating the functional spectrum of blood products. Large proportions of EVs originated from platelets in CPRP and hypACT, whereas very low erythrocyte and monocyte-derived EVs were detected via flow cytometry. EV treatment of chondrocytes enhanced the expression of anabolic markers type II collagen, SRY-box transcription factor 9 (SOX9), and aggrecan compared to full blood products, but also the catabolic marker and tissue remodeling factor matrix metalloproteinase 3, whereas hypACT EVs prevented type I collagen expression. CPRP blood product increased SOX9 protein expression, in contrast to hypACT blood product. However, hypACT EVs induced SOX9 protein expression while preventing interleukin-6 secretion. The results indicate that blood EVs are sufficient to induce chondrogenic gene expression changes in OA chondrocytes, while preventing proinflammatory cytokine release compared to full blood product. This highlights the potential of autologous blood-derived EVs as regulators of cartilage extracellular matrix metabolism and inflammation, as well as candidates for new cell-free therapeutic approaches for OA.

Platelet-rich plasma (PRP) as therapy for cartilage, tendon and muscle damage - German working group position statement

Purpose

Platelet rich plasma (PRP) is widely used in orthopaedics, but is still heavily debated. Therefore, a survey among the German “Working Group for Clinical Tissue Regeneration” of the German Society of Orthopaedics and Traumatology was conducted to achieve a consensus about the current therapeutical potential of PRP.

Methods

A first survey (n = 65 experts, all orthopaedic/trauma surgeons) was conducted (n = 13 questions). Following, a second round (n = 40 experts) was conducted with 31 questions to achieve consensus in 5 categories: three most common indications, PRP application, future research areas.

Results

Therapeutic PRP application was regarded as useful (89%), possibly even more important in the future (90%). Most common indications were tendon pathologies (77%), osteoarthritis (OA) (68%), muscle injuries (57%) and cartilage damage (51%). Consensus was reached in 16/31 statements. The application of PRP for early knee OA (Kellgren-Lawrence grade II) was regarded as potentially useful, as well as for acute and chronic tendinopathies. For chronic lesions (cartilage, tendons), multiple injections (2–4) were seen preferable to singular injections. However, no sufficient data exists on the time interval between the injections. Standardization of PRP preparation, application, frequency, as well as determining the range of indication is strongly recommended.

Conclusions

There is a need of further standardization of the PRP preparation methods, indication and application protocols for knee OA and other indications, which must be further evaluated in basic science studies and randomized controlled clinical trials.

Level of evidence

Consensus of expert opinion, Level V.

Importance of Timing of Platelet Lysate-Supplementation in Expanding or Redifferentiating Human Chondrocytes for Chondrogenesis

Osteoarthritis (OA) in articular joints is a prevalent disease. With increasing life expectancy, the need for therapies other than knee replacement arises. The intrinsic repair capacity of cartilage is limited, therefore alternative strategies for cartilage regeneration are being explored. The purpose of this study is first to investigate the potential of platelet lysate (PL) as a xeno-free alternative in expansion of human OA chondrocytes for cell therapy, and second to assess the effects of PL on redifferentiation of expanded chondrocytes in 3D pellet cultures. Chondrocytes were isolated from human OA cartilage and subjected to PL in monolayer culture. Cell proliferation, morphology, and expression of chondrogenic genes were assessed. Next, PL-expanded chondrocytes were cultured in 3D cell pellets and cartilage matrix production was assessed after 28 days. In addition, the supplementation of PL to redifferentiation medium for the culture of expanded chondrocytes in 3D pellets was evaluated. Glycosaminoglycan (GAG) and collagen production were evaluated by quantitative biochemical analyses, as well as by (immuno)histochemistry. A dose-dependent effect of PL on chondrocyte proliferation was found, but expression of chondrogenic markers was decreased when compared to FBS-expanded cells. After 28 days of subsequent 3D pellet culture, GAG production was significantly higher in pellets consisting of chondrocytes expanded with PL compared to controls. However, when used to supplement redifferentiation medium for chondrocyte pellets, PL significantly decreased the production of GAGs and collagen. In conclusion, chondrocyte proliferation is stimulated by PL and cartilage production in subsequent 3D culture is maintained. Furthermore, the presences of PL during redifferentiation of 3D chondrocyte strongly inhibits GAG and collagen content. The data presented in the current study indicate that while the use of PL for expansion in cartilage cell therapies is possibly beneficial, intra-articular injection of the product in the treatment of OA might be questioned.

What Is the Appropriate Price for Platelet-Rich Plasma Injections for Knee Osteoarthritis? A Cost-Effectiveness Analysis Based on Evidence From Level I Randomized Controlled Trials

PURPOSE

To identify the price of treatment at which platelet-rich plasma (PRP) is cost-effective relative to hyaluronic acid (HA) and saline solution intra-articular injections.

METHODS

A systemized review process of the PubMed, Embase, and MEDLINE databases was undertaken to identify randomized controlled trials comparing PRP with HA and saline solution with up to 1 year of follow-up. Level I trials that reported Western Ontario and McMaster Universities Arthritis Index Likert scores were included. These scores were converted into utility scores. Cost data were obtained from Centers for Medicare & Medicaid Services fee schedules. Total costs included the costs of the injectable, clinic appointments, and procedures. The change in utility scores from baseline to 6 months and 1 year for the PRP, HA, and saline solution groups was divided by total cost to determine utility gained per dollar and to identify the price needed for PRP to be cost-effective relative to these other injection options.

RESULTS

Nine randomized controlled trials met the inclusion criteria. A total of 882 patients were included: 483 in the PRP group, 338 in the HA group, and 61 in the saline solution group. Baseline mean utility scores ranged from 0.55 to 0.57 for the PRP, HA, and saline solution groups. The 6-month gains in utility were 0.12, 0.02, and -0.06, respectively. The 12-month gains in utility from before injection were 0.14, 0.03, and 0.06, respectively. The lowest total costs for HA and saline solution were $681.93 and $516.29, respectively. For PRP to be cost-effective, the total treatment cost would have to be less than $3,703.03 and $1,192.08 for 6- and 12-month outcomes, respectively.

CONCLUSIONS

For patients with symptomatic knee osteoarthritis, PRP is cost-effective, from the payer perspective, at a total price (inclusive of clinic visits, the procedure, and the injectable) of less than $1,192.08 over a 12-month period, relative to HA and saline solution.

LEVEL OF EVIDENCE

Level I, systematic review.

Dose-Dependent Effects of Platelet-Rich Plasma Powder on Chondrocytes In Vitro

BACKGROUND

Platelet-rich plasma (PRP) is widely used in sports medicine. However, neither preparation nor parameters for clinical application, such as concentration, timing, and number of applications, are standardized, making research and clinical utilization challenging.

PURPOSE

To investigate the effect of varying doses of PRP powder in terms of different concentrations, timing, and number of applications on human chondrocytes in a reproducible cell culture model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A standardized lyophilized platelet growth factor preparation (PRP powder) was used to stimulate human chondrocytes. Chondrocytes were cultivated for 2 weeks with different stimulation frequencies (2×, 3×, 6×) and different concentrations of PRP powders (0.5%, 1%, 5%). Cell proliferation and metabolic cell activity were analyzed on days 7 and 14. Phenotypic changes were visualized through live-dead staining. Chondrogenic differentiation was quantified with enzyme-linked immunosorbent assay to assess the synthesis of procollagen types 1 and 2. Furthermore, sulfated proteoglycans and glycosaminoglycans were analyzed.

RESULTS

Human chondrocytes exhibited a significant dose- and time-dependent increase after 14 days in cell number (1% and 5% PRP powder vs unstimulated control: 7.95- and 15.45-fold increase, respectively; 2× vs 6× stimulation with 5% PRP powder: 4.00-fold increase) and metabolic cell activity (1% and 5% PRP powder vs unstimulated control: 3.27-fold and 3.58-fold change, respectively). Furthermore, cells revealed a significant increase in the amount of bone-specific procollagen type 1 (14 days, 1.94-fold) and sulfated glycosaminoglycans (14 days, 2.69-fold); however, no significant change was observed in the amount of cartilage-specific collagen type 2.

CONCLUSION

We showed that chondrocytes exhibit a significant dose- and time-dependent increase in cell number and metabolic cell activity. The standardized use of growth factor concentrates in cell culture models can contribute to clinical knowledge in terms of dosage and timing of PRP applications.

CLINICAL RELEVANCE

Problems with PRP, such as the absence of standardization, lack of consistency among studies, and unknown dosage, could be solved by using characterized PRP powder made by pooling and lyophilizing multiple platelet concentrates. The innovative PRP powder generates new possibilities for PRP research, as well as for the treatment of patients.

Editorial Commentary: Orthobiologics-The Evolution From Symptom to Structural Modification in the Treatment of Articular Cartilage Defects

The race is on to identify the optimal recipe for the treatment of focal cartilage defects. Although many attempts had been made, beyond the use of osteochondral allografts, the restoration of pristine hyaline cartilage still seems distant and out of reach. The fundamental assumption is that cartilage restoration constructs must provide both structural integrity and adequate biological features that provide the optimal environment for hyaline cartilage formation. Augmentation of biologic scaffolds and grafts with orthobiologic agents may attend to both needs by improving defect fill and integration to the host articular cartilage interface.

Alleviation of synovitis caused by joint instability with application of platelet-rich plasma

INTRODUCTION

Synovitis is an early set and persistent change during the progression of osteoarthritis, which causes symptoms such as pain and swelling of the joints. Platelet-rich plasma (PRP) can release quantities of growth factors and cytokines, and is proved effected in promoting restoration of multiple soft tissues.

MATERIALS AND METHODS

In this study, twenty rabbits were used to establish animal model of synovitis, with the method of severing the anterior and posterior cruciate ligaments and removing the medial meniscus. Then the rabbits were evenly divided into the PRP group and the control group, and each group received injections of PRP and saline respectively once a week for 3 weeks consecutively, with the first injection administered 3 weeks postoperatively.

RESULTS

The platelet count, the concentrations of growth factors in PRP and whole blood were investigated, and the IL-1β concentration in the joint fluid was detected via ELISA. The synovium as well as the adjacent articular cartilage were collected for histological assessment. The platelet concentration in PRP is 6.8 fold of that in the whole blood. The IL-1β level in the PRP group was lower than that in the control group 2 and 3 weeks after the administration of PRP. Histological investigation showed that the inflammatory reaction of the synovium and impact on the cartilage was much abated in the PRP group.

CONCLUSIONS

PRP can effectively alleviate the synovitis caused by osteoarthritis following loss of joint stability. Given the autologous origin, its low cost and low risk features of PRP, it's a promising choice for OA patients to control the symptoms caused by synovitis.

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

Background:

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.

Objective:

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.

Methods:

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.

Results:

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.

Conclusion:

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.