Platelet-rich plasma stimulates porcine articular chondrocyte proliferation and matrix biosynthesis

ALB-PRF facilitates chondrogenesis by promoting chondrocytes migration, proliferation and differentiation

Cartilage injury is common in orthopedics and cartilage tissue engineering provides a therapeutic direction for cartilage regeneration. Albumin (ALB)-platelet-rich fibrin (PRF) is speculated to be an ideal natural scaffold material for cartilage tissue engineering theoretically as a product derived from human venous blood. Through in vitro and in vivo experiments, it was demonstrated that ALB-PRF displayed porous structure and slowly released growth factors (TGF-β1, PDGF-AA, PDGF-AB, PDGF-BB, EGF, IGF-1 and VEGF), ALB-PRF conditioned media promoted proliferation, migration, adhesion, phenotype maintenance and extracellular matrix secretion of rabbit chondrocytes. Moreover, ALB-PRF facilitated chondrogenesis in vivo, the regenerative cartilage formed by ALB-PRF/chondrocytes was histologically similar to that of natural knee joint cartilage, the regenerative cartilage expressed cartilage differentiation marker (SOX9, ACAN and COL II), and proliferation marker PCNA and secreted abundant glycosaminoglycans (GAGs) in extracellular matrix. In conclusion, ALB-PRF promoted the migration, proliferation and phenotype maintenance of chondrocytes in vitro. Its loose, porous structure and rich growth factors contained enhanced cell adhesion and growing into the materials. ALB-PRF facilitated chondrogenesis of chondrocytes in vivo.

Experimental Investigation of the Effect of Polydioxanone Plate and Platelet-Rich Plasma on Cartilage Regeneration

Objectives: This study aimed to investigate the effectiveness of polydioxanone (PDS) plate and platelet-rich plasma (PRP) on the regeneration of cartilage grafts, which are frequently used in nasal and septal surgery. Methods: Fifteen white New Zealand Albino-type female rabbits were used in the study. Our study was carried out on 4 different applications on each animal: cartilage only, cartilage+PRP, cartilage+PDS plate, and cartilage+PRP+PDS plate, and in 3 different periods: the first month, the second month, and the third month. Results: A significant difference was obtained between the groups using cartilage+PRP and cartilage+PRP+PDS only in the first month. When both application types were compared, a statistically significant decrease was found in the histopathological cartilage viability score after PDS use. In examining peripheral chondrocyte proliferation, a statistically significant difference was found only in the third-month comparison. When the group using only cartilage was compared with the group using cartilage+PDS, it was determined that peripheral chondrocyte proliferation was significantly reduced at the end of the third month with PDS. In evaluating fibrosis and foreign body reaction, a statistically significant increase was detected using a PDS plate. In histopathological cartilage viability score statistical analysis, a significant difference was obtained between the groups using cartilage+PRP and cartilage+PRP+PDS only in the first month. Degeneration in the cartilage structure was observed macroscopically in the specimens where the PDS plate was used. Shape change and cartilage deformation were observed in the PDS plate specimens. Conclusions: When the results were examined, this observation coincided with the statistically significant increase in foreign body reaction and fibrosis in the PDS plate groups. However, these results contradicted our hypothesis before the study and the information in the literature. Our results will help provide preliminary information and guidance for future studies and offer a different perspective.

Evaluation of orthobiological ozonized platelet-rich plasma therapy post-arthroscopic suturing and lone partial meniscectomy in the treatment of meniscal tears within degenerative knee osteoarthritis

BACKGROUND

Knee joint osteoarthritis (OA)-related meniscal tears are still sometimes treated in centers by arthroscopic partial meniscectomy (APM), which is then followed by a solitary physical therapy regimen.

OBJECTIVE

The present study was conducted to compare the efficacy of intra-articular injection of ozonized platelet-rich plasma (PRP) and hyaluronic acid following arthroscopic suturing, and APM to treat meniscal tear degenerative type.

METHODS

In a randomized trial of prospective comparative research, 104 patients, all of whom had meniscal tears due to OA of the knee, were randomly divided into two groups. The participants in Group A (55 patients) were given intra-articular ozonized PRP and hyaluronate therapeutics, following arthroscopic suturing of meniscal tear treatment (ASMT) of degenerative knee joint OA. Group B (49 patients) was prepared for APM alone. Both groups were followed by physical therapy and a follow up visit throughout 12, 24, and 36 months. The WOMAC and Lequesne scores were evaluated.

RESULTS

At every follow up visit for 6, 12, and 24, months, there was a significant decline in the mean of WOMAC and Lequesne scores in Groups A and B relative to baseline. Additionally, Group A significantly (P<0.0001) outperformed Group B at 12, 24, and 36 months for both Lequesne's and WOMAC scores. There were infection, stiffness, and widespread OA knee degeneration detected in Group B while no serious adverse effects were observed in Group A.

CONCLUSION

The study's findings demonstrated that physical and intra-articular orthobiological ozonized PRP and hyaluronate therapies were more effective than APM in treating degenerative knee joint OA.

Morphological and Quantitative Parametric MRI Follow-up of Cartilage Changes Before and After Intra-articular Injection Therapy in Patients With Mild to Moderate Knee Osteoarthritis: A Randomized, Placebo-Controlled Trial

BACKGROUND

Intra-articular injections are routinely used for conservative treatment of knee osteoarthritis (OA). The detailed comparative therapeutic effects of these injections on cartilage tissue are still unclear.

OBJECTIVE

The aim of this study was to detect and compare knee cartilage changes after intra-articular injection of glucocorticoid, hyaluronic acid, or platelet-rich plasma (PRP) to placebo using quantitative (T2 and T2* mapping) and morphological magnetic resonance imaging parameters in patients with mild or moderate osteoarthritis.

MATERIALS AND METHODS

In a double-blinded, placebo-controlled, single-center trial, knees with mild or moderate osteoarthritis (Kellgren-Lawrence grade 1-3) were randomly assigned to an intra-articular injection with 1 of these substances: glucocorticoid, hyaluronic acid, PRP, or placebo. Cartilage degeneration on baseline and follow-up magnetic resonance imaging scans (after 3 and 12 months) was assessed by 2 readers using quantitative T2 and T2* times (milliseconds) and morphological parameters (modified Outerbridge grading, subchondral bone marrow edema, subchondral cysts, osteophytes).

RESULTS

One hundred twenty knees (30 knees per treatment group) were analyzed with a median patient age of 60 years (interquartile range, 54.0-68.0 years). Interreader reliability was good for T2 (ICC, 0.76; IQR, 0.68-0.83) and T2* (ICC, 0.83; IQR, 0.76-0.88) measurements. Morphological parameters showed no significant changes between all groups after 3 and 12 months. T2 mapping after 12 months showed the following significant ( P = 0.001-0.03) changes between groups in 6 of 14 compartments: values after PRP injection decreased compared with glucocorticoid in 4 compartments (complete medial femoral condyle and central part of lateral condyle) and compared with placebo in 2 compartments (anterior and central part of medial tibial plateau); values after glucocorticoid injection decreased compared with placebo in 1 compartment (central part of medial tibial plateau). No significant changes were seen for T2 and T2* times after 3 months and T2* times after 12 months. No correlation was found between T2/T2* times and Kellgren-Lawrence grade, age, body mass index, or pain (Spearman ρ, -0.23 to 0.18).

CONCLUSIONS

Platelet-rich plasma injection has a positive long-term effect on cartilage quality in the medial femoral compartment compared to glucocorticoid, resulting in significantly improved T2 values after 12 months. For morphological cartilage parameters, injections with glucocorticoid, PRP, or hyaluronic acid showed no better effect in the short or long term compared with placebo.

Impact of arthroscopy on post-procedure intra-articular elbow injections: A cadaveric study

OBJECTIVE

To determine the influence of arthroscopy and injection volume on post-procedure intra-articular (IA) injection extravasation.

STUDY DESIGN

Ex vivo prospective study.

SAMPLE POPULATION

A total of 40 paired canine cadaver forelimbs.

METHODS

After radiographs and computed tomography (CT) scans with three-dimensional (3D) digital bone model reconstructions, elbows were randomly assigned to the arthroscopy or control group and randomly assigned to receive an IA injection of 2 or 4 mL of contrast. Elbow arthroscopy was performed on assigned specimens, followed by IA injections of contrast in all elbows, and imaging was repeated. 3D digital model volumes were compared. Images were interpreted and scored for extravasation by a radiologist unaware of treatment and volume assignments.

RESULTS

Based on CT images and regardless of treatment group, IA injections of 4 mL resulted in a mean extravasation score of 2.25 (SD 0.97) versus 1.55 (SD 1.05) (p = .02) for 2 mL IA injections. The change in 3D model volumes after IA injections was a mean of 13.2 cm3 (SD 5.85) after 4 mL injections, compared to 6.97 cm3 (SD 6.28) (p = .003) after 2 mL injections. On radiographic evaluation, but not CT, the mean extravasation scores were 2.45 (SD 1.15) for the arthroscopy group and 1.25 (SD 0.79) for the control group (p < .001).

CONCLUSION

A larger volume of IA injection resulted in higher CT extravasation scores and larger 3D volumes regardless of arthroscopic treatment.

CLINICAL SIGNIFICANCE

IA injections performed immediately after arthroscopy resulted in 50% or less extravasation, especially with a smaller IA injection volume.

Orthobiologic Management Options for Degenerative Disc Disease

Degenerative disc disease (DDD) is a pervasive condition that limits quality of life and burdens economies worldwide. Conventional pharmacological treatments primarily aimed at slowing the progression of degeneration have demonstrated limited long-term efficacy and often do not address the underlying causes of the disease. On the other hand, orthobiologics are regenerative agents derived from the patient's own tissue and represent a promising emerging therapy for degenerative disc disease. This review comprehensively outlines the pathophysiology of DDD, highlighting the inadequacies of existing pharmacological therapies and detailing the potential of orthobiologic approaches. It explores advanced tools such as platelet-rich plasma and mesenchymal stem cells, providing a historical overview of their development within regenerative medicine, from foundational in vitro studies to preclinical animal models. Moreover, the manuscript delves into clinical trials that assess the effectiveness of these therapies in managing DDD. While the current clinical evidence is promising, it remains insufficient for routine clinical adoption due to limitations in study designs. The review emphasizes the need for further research to optimize these therapies for consistent and effective clinical outcomes, potentially revolutionizing the management of DDD and offering renewed hope for patients.

The Nrf2/HO-1 pathway participates in the antiapoptotic and anti-inflammatory effects of platelet-rich plasma in the treatment of osteoarthritis

INTRODUCTION

We aimed to explore the molecular mechanisms through which platelet-rich plasma (PRP) attenuates osteoarthritis (OA)-induced pain, apoptosis, and inflammation.

METHODS

An in vivo model of OA was established by injuring rats using the anterior cruciate ligament transection method, whereas an in vitro model was generated by exposing chondrocytes to interleukin (IL)-1β. Both models were then treated with PRP.

RESULTS

In both the in vivo and in vitro models, OA led to the suppression of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway, whereas treatment with PRP reactivated this molecular axis. Inhibition of the Nrf2/HO-1 pathway using the Nrf2 inhibitor brusatol or through Nrf2 gene silencing counteracted the effects of PRP in reducing the tenderness and thermal pain thresholds of OA rats. Additionally, PRP reduced the mRNA expression of IL-1β, IL-6, tumor necrosis factor-alpha (TNF-α), and matrix metallopeptidase 13 (MMP-13) and the protein expression of B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X-protein (Bax), and caspase-3. Furthermore, inflammation and apoptosis were induced by brusatol treatment or Nrf2 silencing. Additionally, in the in vitro model, PRP treatment increased the proliferation of chondrocytes and attenuated their inflammatory response and apoptosis, effects that were abrogated by Nrf2 depletion.

CONCLUSIONS

The Nrf2/HO-1 pathway participates in the PRP-mediated attenuation of OA development by suppressing inflammation and apoptosis.

Bioinspired 3D scaffolds with antimicrobial, drug delivery, and osteogenic functions for bone regeneration

A major clinical challenge today is the large number of bone defects caused by diseases or trauma. The development of three-dimensional (3D) scaffolds with adequate properties is crucial for successful bone repair. In this study, we prepared biomimetic mesoporous bioactive glass (MBG)-based scaffolds with and without ceria addition (up to 3 mol %) to explore the biological structure and chemical composition of the marine sponge Spongia Agaricina (SA) as a sacrificial template. Micro-CT examination revealed that all scaffolds exhibited a highly porous structure with pore diameters primarily ranging from 143.5 μm to 213.5 μm, facilitating bone ingrowth. Additionally, smaller pores (< 75 μm), which are known to enhance osteogenesis, were observed. The undoped scaffold displayed the highest open porosity value of 90.83%. Cytotoxicity assessments demonstrated that all scaffolds were noncytotoxic and nongenotoxic toward osteoblast cells. Moreover, scaffolds with higher CeO2 content promoted osteogenic differentiation of dental pulp stem cells, stimulating calcium and osteocalcin secretion. The scaffolds also exhibited antimicrobial and antibiofilm effects against Staphylococcus aureus (S. aureus) as well as drug delivery ability. Our research findings indicated that the combination of MBG, natural biological structure, and the addition of Ce exhibited a synergistic effect on the structure and biological properties of scaffolds for applications in bone tissue engineering.

Effects of intra-articular injection of platelet-rich plasma on the inflammatory process and histopathological characteristics of cartilage and synovium in animals with osteoarthritis: a systematic review with meta-analysis

BACKGROUND

Osteoarthritis (OA) affects the entire joint, causing structural changes in articular cartilage, subchondral bone, ligaments, capsule, synovial membrane, and periarticular muscles that afflicts millions of people globally, leading to persistent pain and diminished quality of life. The intra-articular use of platelet-rich plasma (PRP) is gaining recognition as a secure therapeutic approach due to its potential regenerative capabilities. However, there is controversial clinical data regarding efficacy of PRP for OA treatment. In this context, gathering scientific evidence on the effects of PRP in treating OA in animal models could provide valuable insights into understanding its impact on aspects like cartilage health, synovial tissue integrity, and the inflammatory process in affected joints. Thus, the objective of this study was to assess the effects of PRP injections on inflammation and histopathological aspects of cartilage and synovium in animal models of OA through a comprehensive systematic review with meta-analysis.

METHODS

A electronic search was conducted on Medline, Embase, Web of Science, The Cochrane Library, LILACS, and SciELO databases for relevant articles published until June 2022. A random-effects meta-analysis was employed to synthesize evidence on the histological characteristics of cartilage and synovium, as well as the inflammatory process. The GRADE approach was utilized to categorize the quality of evidence, and methodological quality was assessed using SYRCLE's RoB tool.

RESULTS

Twenty-one studies were included in the review, with twelve of them incorporated into the meta-analysis. PRP treatment demonstrated superior outcomes compared to the control group in terms of cartilage histology (very low quality; p = 0.0002), synovium histology (very low quality; p < 0.0001), and reductions in proinflammatory markers, including IL-1 (low quality; p = 0.002), IL-6 (very low quality; p < 0.00001), and TNF-α (very low; p < 0.00001). However, PRP treatment did not yield a significant impact on PDGF-A levels (very low quality; p = 0.81).

CONCLUSION

PRP appears capable of reducing proinflammatory markers (IL-1, IL-6, TNF-α) and mitigating cartilage and synovium damage in animals with OA. However, the levels of evidence of these findings are low to very low. Therefore, more rigorous studies with larger samples are needed to improve the quality of evidence.

PROSPERO REGISTRATION

CRD42022250314.

Mesenchymal Stem Cells Cultured in a 3D Microgel Environment Containing Platelet-Rich Plasma Significantly Modify Their Chondrogenesis-Related miRNA Expression

The aim of this work is to study the effect of platelet factors on the differentiation of mesenchymal stem cells (MSCs) to hyaline cartilage chondrocytes in a three-dimensional environment. MSCs were cultured in a microgel environment with a chondrogenic medium. The microgel consisted of microspheres that combine gelatin and platelet-rich plasma (PRP). The gelatin/PRP microdroplets were produced by emulsion. The gelatin containing the microdroplets was enzymatically gelled, retaining PRP and, just before seeding the cells, platelets were activated by adding calcium chloride so that platelet growth factors were released into the culture media but not before. Platelet activation was analyzed before activation to rule out the possibility that the gelatin cross-linking process itself activated the platelets. The gene expression of characteristic chondrogenic markers and miRNA expression were analyzed in cells cultured in a differentiation medium and significant differences were found between gelation/PRP microgels and those containing only pure gelatin. In summary, the gelatin microspheres effectively encapsulated platelets that secreted and released factors that significantly contributed to cellular chondrogenic differentiation. At the same time, the microgel constituted a 3D medium that provided the cells with adherent surfaces and the possibility of three-dimensional cell-cell contact.

The Influence of Industry Affiliation on Randomized Controlled Trials of Platelet-Rich Plasma for Knee Osteoarthritis

BACKGROUND

Industry funding and corporate sponsorship have played a significant role in the advancement of orthopaedic research and technology. However, this relationship raises concerns for how industry association may bias research findings and influence clinical practice.

PURPOSE

To determine whether industry affiliation plays a role in the outcomes of randomized controlled trials (RCTs) investigating platelet-rich plasma (PRP).

STUDY DESIGN

Meta-analysis; Level of evidence, 2.

METHODS

A search of the PubMed, Cochrane, and MEDLINE databases for RCTs published between 2011 and the present comparing PRP versus hyaluronic acid, corticosteroid, or placebo for the treatment of knee osteoarthritis was performed. To determine industry affiliation, the conflict of interest, funding, and disclosure sections of publications were assessed, and all authors were assessed through the American Academy of Orthopaedic Surgeons disclosure database and the Centers for Medicare & Medicaid Services open payments database. Studies were classified as industry affiliated (IA) or non-industry affiliated (NIA). The outcomes of each study were rated as favorable, analogous, or unfavorable according to predefined criteria.

RESULTS

A total of 37 studies (6 IA and 31 NIA) were available for analysis. Overall, 19 studies (51.4%) reported PRP as favorable compared with other treatment options, while 18 studies (48.6%) showed no significant differences between PRP and other treatment methods. There was no significant difference in qualitative conclusions between the IA and NIA groups, with the IA group having 3 favorable studies and 3 analogous studies and the NIA group having 16 favorable studies and 15 analogous studies (P = .8881). When comparing IA versus NIA studies using 6- and 12-month Western Ontario and McMaster Universities Arthritis Index and International Knee Documentation Committee scores, there were no significant differences in outcomes.

CONCLUSION

The results of this study demonstrated that qualitative conclusions and outcome scores were found to not be associated with industry affiliation. Although the results of this study suggest that there is no influence of industry involvement on RCTs examining PRP, it is still necessary to carefully evaluate pertinent commercial affiliations when reviewing recommendations from studies before adopting new treatment approaches, such as the use of PRP for knee osteoarthritis.

Converse modulation of Wnt/β-catenin signaling during expansion and differentiation phases of Infrapatellar fat pad-derived MSCs for improved engineering of hyaline cartilage

Mesenchymal stem cells (MSCs) are potential candidates in cell-based therapy for cartilage repair and regeneration. However, during chondrogenic differentiation, MSCs undergo undesirable hypertrophic maturation. This poses a risk of ossification in the neo-tissue formed that eventually impedes the clinical use of MSCs for cartilage repair. TGF-β is a potent growth factor used for chondrogenic differentiation of MSCs, however, its role in hypertrophy remains ambiguous. In the present work, we decipher that TGF-β activates Wnt/β-catenin signaling through SMAD3 and increases the propensity of Infrapatellar fat pad derived MSCs (IFP-MSCs) towards hypertrophy. Notably, inhibiting TGF-β induced Wnt/β-catenin signaling suppresses hypertrophic progression and enhances chondrogenic ability of IFP-MSCs in plasma hydrogels. Additionally, we demonstrate that activating Wnt signaling during expansion phase, promotes proliferation and reduces senescence, while improving stemness of IFP-MSCs. Thus, conversely modulating Wnt signaling in vitro during expansion and differentiation phases generates hyaline-like cartilage with minimal hypertrophy. Importantly, pre-treatment of IFP-MSCs encapsulated in plasma hydrogel with Wnt modulators followed by subcutaneous implantation in nude mice resulted in formation of a cartilage tissue with negligible calcification. Overall, this study provides technological advancement on targeting Wnt/β-catenin pathway in a 3D scaffold, while maintaining the standard chondro-induction protocol to overcome the challenges associated with the clinical use of MSCs to engineer hyaline cartilage.

Platelet-Rich Plasma for Knee Osteoarthritis: What Does the Evidence Say?

The utilization of platelet-rich-plasma as a therapeutic intervention for knee osteoarthritis has gained immense attention since 2008. The increase in the number of scientific publications dedicated to this area can be attributed to the majority of favorable results reported in clinical trials and basic science studies. However, despite the growing evidence, the use of platelet-rich plasma in clinical practice still poses controversial aspects. The potential mechanisms of action described for platelet-rich-plasma so far indicate that it could serve as a disease-modifying drug, acting to counteract important aspects of knee osteoarthritis pathophysiology (cartilage breakdown, inflammation, and bone remodeling). Nevertheless, its efficacy in slowing down the progression of knee osteoarthritis remains unproven. While inconsistencies have been noted, the majority of controlled clinical trials and meta-analyses advocate for the utilization of platelet-rich-plasma in treating knee osteoarthritis, as it has demonstrated greater efficacy than hyaluronic acid and placebo, with a follow-up of at least 1 year. Despite advancements made in certain areas, significant diversity persists regarding the formulations used, therapeutic regimen, extended follow-up periods, patient selection, and assessment of clinically relevant outcomes. Consequently, the leading clinical practice guidelines do not recommend its use. In light of the emerging evidence, this narrative review aims to provide an objective evaluation of the recent available scientific literature (last 5 years) focused on randomized clinical trials and meta-analyses to present a current overview of the topic.

Hypoxia Preconditioned Serum (HPS) Promotes Proliferation and Chondrogenic Phenotype of Chondrocytes In Vitro

Autologous chondrocyte implantation (ACI) for the treatment of articular cartilage defects remains challenging in terms of maintaining chondrogenic phenotype during in vitro chondrocyte expansion. Growth factor supplementation has been found supportive in improving ACI outcomes by promoting chondrocyte redifferentiation. Here, we analysed the chondrogenic growth factor concentrations in the human blood-derived secretome of Hypoxia Preconditioned Serum (HPS) and assessed the effect of HPS-10% and HPS-40% on human articular chondrocytes from osteoarthritic cartilage at different time points compared to normal fresh serum (NS-10% and NS-40%) and FCS-10% culture conditions. In HPS, the concentrations of TGF-beta1, IGF-1, bFGF, PDGF-BB and G-CSF were found to be higher than in NS. Chondrocyte proliferation was promoted with higher doses of HPS (HPS-40% vs. HPS-10%) and longer stimulation (4 vs. 2 days) compared to FCS-10%. On day 4, immunostaining of the HPS-10%-treated chondrocytes showed increased levels of collagen type II compared to the other conditions. The promotion of the chondrogenic phenotype was validated with quantitative real-time PCR for the expression of collagen type II (COL2A1), collagen type I (COL1A1), SOX9 and matrix metalloproteinase 13 (MMP13). We demonstrated the highest differentiation index (COL2A1/COL1A1) in HPS-10%-treated chondrocytes on day 4. In parallel, the expression of differentiation marker SOX9 was elevated on day 4, with HPS-10% higher than NS-10/40% and FCS-10%. The expression of the cartilage remodelling marker MMP13 was comparable across all culture conditions. These findings implicate the potential of HPS-10% to improve conventional FCS-based ACI culture protocols by promoting the proliferation and chondrogenic phenotype of chondrocytes during in vitro expansion.

Comparison of Functional Outcome of Single Versus Multiple Intra-articular Platelet-Rich Plasma Injection for Early Osteoarthritis Knee

Background Osteoarthritis (OA) is a leading cause of pain and disability and has a negative impact on patients' quality of life. Platelet-rich plasma (PRP) has emerged as a promising treatment for various orthopaedic conditions, such as tendinopathies, nonunion, and arthritis of the knee. We sought to determine whether a single intra-articular platelet-rich plasma injection has better functional and pain outcomes when compared with multiple (two) articular platelet-rich plasma injections given in the early stages of OA of the knee, measured using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and the visual analogue scale for pain (VAS) at the sixth week, third month, and sixth month. Materials and methods The prospective observational study was conducted among patients diagnosed with early OA who presented to the Department of Orthopaedics, R. L. Jalappa Hospital and Research Centre, Kolar, Karnataka, India, between January 2020 and June 2021. A total of 64 patients were divided into: (i) S-PRP group (34 patients), which received a single PRP injection, and (ii) M-PRP group (30 patients), which received multiple (two) PRP injections, one on presentation and the second in the thirdmonth. VAS and WOMAC scores to assess functional outcomes were used at the first visit before the intervention and at the sixth week, third month, and sixth month. Results The average age of the patients was 55.26 years in the S-PRP group and 51.13 years in the M-PRP group. Both genders were equal among study participants in the M-PRP group, but 79.4% were females in the S-PRP group. In the S-PRP group, 74% had grade II OA and 26% had grade I OA. In the M-PRP group, 60% had grade II OA and the remaining 40% had grade I OA. The decreasing trend of pain and functional limitation, which was measured by VAS and WOMAC, respectively, was observed in both groups at pre-injection, sixth week, third month, and sixth month. These differences were statistically significant. The mean difference in VAS score between the pre-injection period and at six months was 4 in the S-PRP group, whereas it was 5.77 in the M-PRP group, and this was statistically significant (p-value = 0.001). Thus, multiple PRP injections have a greater response to pain reduction when compared to single PRP injections, according to the VAS score. According to the WOMAC score, there is no statistically significant difference in the treatment response with PRP injection between the S-PRP and M-PRP groups at any follow-up period. Conclusion According to the VAS score, single PRP injections have a lower pain score than multiple PRP injections until three months of follow-up, while at six months, single PRP injections have no better effect than multiple PRP injections. But multiple PRP injections have a higher reduction in the intensity of pain when compared to single PRP injections during the follow-up period. According to the WOMAC score, there is no statistically significant difference in the treatment response with PRP injection between S-PRP and M-PRP groups.

The role of Platelet-Rich Plasma (PRP) intraarticular injections in restoring articular cartilage of osteoarthritic knees. A systematic review and meta-analysis

Objective

To assess the effect of PRP on knee articular cartilage content (thickness/volume) and examine the correlation between cartilage changes and clinical outcomes in patients with knee OA.

Method

A systematic literature search was performed using the Cochrane methodology in four online databases. Studies were included if they reported on cartilage content with cross-sectional imaging pre- and post-injection. A random-effects model meta-analysis was performed. Correlation with clinical outcomes was evaluated.

Results

14 studies (n ​= ​1099 patients) from 1452 records met the inclusion criteria: seven RCTs (n ​= ​688), one prospective (n ​= ​50), one retrospective (n ​= ​68), and four case-series (n ​= ​224). The PRP preparation process and treatment protocol varied widely (follow-up 6-12 months). In meta-analysis, PRP treatment was not associated with a significant increase in cartilage thickness (4 studies, n ​= ​187, standardized mean difference: Hedges g: 0.079; 95%CI: 0.358 - 0.516; p ​= ​0.723). Meta-analysis of 3 RCTs (n ​= ​112) showed no significant difference in the change of overall knee cartilage content with PRP injections compared with no PRP (Hedges' g: 0.217; 95%CI: 0.177 - 0.611; P ​= ​0.281).

Conclusion

The current literature does not support the PRP as chondrogenic in treatment of knee OA. However, there is substantial heterogeneity in the evaluated studies which limits the robustness of any conclusion. An adequately powered RCT, with a standardized PRP regime and standardized high-resolution MRI is needed to definitely define any effect of PRP on knee cartilage content and its relation to clinical outcomes. Until such high-quality evidence becomes available, we recommend that PRP is not administered with the intention of promoting chondrogenesis.

Repeated Intra-Articular Administration of Platelet-Rich Plasma (PRP) in Temporomandibular Disorders: A Clinical Case Series

Background: Temporomandibular joint disorders (TMDs) are manifested, inter alia, by pain and limited scope of the mandibular abduction. Among the treatment strategies for these ailments, intra-articular injections of autologous blood preparations, including platelet-rich plasma (PRP), are administered. This prospective case series was aimed at assessing the effectiveness of repeated platelet-rich plasma (PRP) administration to the TMJ cavities in terms of reducing articular pain and increasing the mobility of the mandible. Material and methods: 40 consecutive patients diagnosed with TMJ pain qualified for the case series. The entire treatment program consisted of five PRP administrations and a summary appointment. Regression was analyzed for (1) intensity of spontaneous pain; (2) effectiveness of spontaneous pain relief; (3) mastication efficiency values; (4) painless mandibular abduction; (5) maximum mouth opening. The correlations between the abovementioned variable series were analyzed. Results: The mean spontaneous pain decreased consistently with successive PRP administrations in line with the regression model: −0.4x + 4.2 (R2 = 0.98). Articular pain improvement was reported in 71% of joints treated. Improvement in chewing quality at the end of the entire injection cycle was found in 63% of patients. The equations for the linear regression models for painless mandibular abduction (five applications of PRP) and maximum mouth opening (the first four applications of PRP) were x + 34 (R2 = 0.89) and 0.6x + 43.6 (R2 = 0.96), respectively. Improvement in these domains was found in 78% and 53% of patients, respectively. The strongest correlations were found between pain and chewing efficiency (−0.95), pain and painless mandible abduction (−0.96), and painless mandibular abduction and mastication efficiency (0.94). Conclusion: PRP injections into TMJ cavities should be considered as a low invasive, highly accessible form of treatment for various TMDs causing pain and mandible movement limitation.

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.

Assessment of Characteristics and Methodological Quality of the Top 50 Most Cited Articles on Platelet-Rich Plasma in Musculoskeletal Medicine

Background:

The wide range of clinical applications and controversial scientific evidence associated with platelet-rich plasma (PRP) therapy in musculoskeletal medicine requires an examination of the most commonly cited studies within this field.

Purpose:

To identify the 50 most cited articles on PRP, assess their study design, and determine any correlations between the number of citations and level of evidence (LoE) or methodological quality.

Study Design:

Cross-sectional study.

Methods:

The Web of Science database was queried to identify the top 50 most cited articles on PRP in orthopaedic surgery. Bibliometric characteristics, number of citations, and LoE were recorded. Methodological quality was evaluated using the Modified Coleman Methodology Score (MCMS), Methodological Index for Non-randomized Studies (MINORS), and Minimum Information for Studies Evaluating Biologics in Orthopaedics (MIBO). The Pearson correlation coefficient and Spearman correlation coefficient (r_S) were used to determine the degree of correlation between the number of citations or citation density and LoE, MCMS, MINORS score, and MIBO score. Student t tests were performed for 2-group comparisons.

Results:

The top 50 articles were published between 2005 and 2016 in 21 journals. The mean number of citations and citation density were 241 ± 94 (range, 151-625) and 23 ± 8, respectively, and the mean LoE was 2.44 ± 1.67, with 15 studies classified as LoE 1. The mean MCMS, MINORS score, and MIBO score were 66.9 ± 12.6, 16 ± 4.7, and 12.4 ± 3.7, respectively. No correlation was observed between the number of citations or citation density and LoE, MCMS, MINORS score, and MIBO score. A significant difference (P = .02) was noted in LoE in articles from the United States (3.56 ± 1.7) versus outside the United States (2 ± 1.5). Seven of the 8 in vivo studies were published between 2005 and 2010, whereas 19 of the 25 clinical outcome investigations were published between 2011 and 2016. Studies that were published more recently were found to significantly correlate with number of citations (r_S = –0.38; P = .01), citation density (r_S = 0.36; P = .01), and higher LoE (r_S = 0.47; P = .01).

Conclusion:

The top 50 most cited articles on PRP consisted of high LoE and fair methodological quality. There was a temporal shift in research from in vivo animal studies toward investigations focused on clinical outcomes.

A prospective randomized double-blind clinical trial to assess the effects of leukocyte-reduced platelet-rich plasma on pro-inflammatory, degradative, and anabolic biomarkers after closed pilon fractures

Posttraumatic osteoarthritis (PTOA) significantly affects patients with pilon fractures even after adequate anatomical reduction, and treatment strategies targeting the biologic mediators of PTOA are needed. This study was designed to determine the effects of intra-articular injection of platelet-rich plasma (PRP) on synovial fluid (SF) biomarkers for patients undergoing open reduction and internal fixation (ORIF) of pilon fractures. Patients undergoing staged management of pilon fractures were enrolled in a prospective, double-blinded, randomized, and placebo-controlled clinical trial to determine the effects of a single intra-articular injection of leukocyte-reduced PRP on SF biomarkers. Arthrocentesis of the injured and uninjured ankles was performed at the time of external skeletal fixation (ESF) and ORIF. Patients were randomized to receive either autogenous leukocyte-reduced PRP or saline (control) via intra-articular injection into the injured ankle at the time of ESF. SF biomarker concentrations were compared-uninjured, injured pretreatment, and saline-injected or PRP-injected. Eleven patients (PRP, n = 5; saline, n = 6) completed the study. Twenty-one uninjured, and 11 injured pretreatment, five PRP-treated, and six saline-treated SF samples were analyzed. PRP-treated SF contained significantly higher levels of PDGF-AA (p = 0.046) and significantly lower levels of MMP-3 (p = 0.042), MMP-9 (p = 0.009), IL-1β (p = 0.049), IL-6 (p < 0.01), IL-8 (p = 0.048), and PGE2 (p < 0.04). This study provided mechanistic data to suggest that a single intraarticular injection of leukocyte-reduced PRP is associated with anti-inflammatory, anti-degradative, and anabolic responses compared with saline control. These findings provide the impetus for investigating long-term clinical outcomes after PRP injection as an orthobiologic adjunct to ORIF for mitigating the incidence and severity of PTOA after pilon fractures.

Role of Triple Injection Platelet-Rich Plasma for Osteoarthritis Knees: A 2 Years Follow-Up Study

PURPOSE

To assess the clinical outcomes of intra-articular Platelet-rich plasma (PRP) injection in knee osteoarthritis (OA) at 2 year follow-up.

METHODS

This was a prospective interventional study. 68 cases (105 knees) with Kellgren-Lawrence (KL) grades I, II and III knee OA received 3 intra-articular injections of PRP 1 month apart. The cases were followed up for 2-years. Outcomes were measured using Western Ontario and McMaster Universities Arthritis Index (WOMAC) score and Visual analog scale (VAS) scores.

RESULTS

The mean age was 51.7 years. 18 knees had KL grade I, 55 had grade II and 32 had grade III OA. The mean pre-treatment VAS score decreased significantly at 1 year (mean difference - 5.3, p = 0.003) and 2 year follow-up (mean difference - 6, p = 0.007). The mean pre-treatment WOMAC score decreased significantly at 1 year (mean difference - 45.9, p = 0.011) and at 2 year (mean difference - 52.4, p = 0.009). The WOMAC and VAS scores improved significantly from baseline to final follow-up across all KL grades (p = 0.001 and 0.001, 0.009 and 0.007, 0.021 and 0.017 for WOMAC and VAS across KL grade I, II and III, respectively). There was no significant differences in WOMAC and VAS scores between three KL grades at final follow-up (p = 0.17 and 0.09, respectively), although the baseline scores had significant difference (p = 0.001 for both VAS and WOMAC) with worse scores in higher KL grades. The variables like age, sex, BMI, KL grade, baseline VAS and baseline WOMAC did not predict the final VAS and WOMAC scores.

CONCLUSION

Triple injection of intra-articular PRP given one month apart significantly relieves the symptoms of knee OA till 2 years in KL grade I, II and III. The improvement in symptoms at 2-year follow-up did not differ across different KL grades.

Intra-Articular Platelet-Rich Plasma Injections in Knee Osteoarthritis: A Review of Their Current Molecular Mechanisms of Action and Their Degree of Efficacy

Knee osteoarthritis (OA) is estimated to affect more than 10% of the population, with a lifetime risk of 45%. Contemporary guidelines advise control of body weight, therapeutic physical exercise, drug treatment (oral non-steroidal anti-inflammatory drugs, paracetamol, opioids), and mechanical aids (walking aids, braces, orthoses). Nevertheless, these treatments typically have only short-term benefits. Intra-articular corticosteroids are typically advised, but only for short-term pain alleviation, given that their benefits last only a few weeks. The efficacy of hyaluronic acid is controversial. When the aforesaid options fail, total knee arthroplasty is generally recommended as an efficacious treatment. However, it is costly and can involve medical and postoperative complications. Therefore, determining alternate safe and effective treatments for knee OA is paramount. Platelet-rich plasma (PRP) has lately been investigated for the treatment of knee OA. This article reviews recent knowledge concerning PRP’s molecular mechanisms of action. The effectiveness of intra-articular PRP injections in the knee joint remains controversial, although most recent publications show pain alleviation in the short term. Orthopedic surgeons treating people with knee OA are becoming increasingly interested in PRP, despite indecisive clinical data and basic science information. Further studies comparing PRP with placebo are required.

Chondroprotective effects of multiple PRP injections in osteoarthritis by apoptosis regulation and increased aggrecan synthesis- Immunohistochemistry based Guinea pig study

OBJECTIVE

Use of Immunohistochemistry as a tool to assess anti-apoptotic effects and cartilage regeneration effects of PRP in guinea pig model of spontaneous OA.

STUDY DESIGN

Controlled Laboratory Study involving Dunkin-Hartley guinea pigs.

METHODS

12 Dunkin-Hartley guinea pigs (weighing ∼600-800 g) were chosen for this study. One knee of each animal received 3 injections of allogenic PRP at weekly intervals (Group A = 12 Knees). The other knee received normal saline and acted as the control group (Group B = 12 Knees). Half of the animals from each group (subgroups A3 & B3 = 6 Knees each) were sacrificed at 3 months, and the remaining half (subgroups A6 & B6 = 6 Knees each) were sacrificed at 6 months after intervention. Immunohistochemistry (IHC) staining and evaluation were done for Collagen-II, Caspase-3 and Aggrecan.

RESULTS

The mean IHC score for Caspase-3 were significantly low in PRP knees compared to placebo Knees at 3 months (P = 0.031) and 6 months (P = 0.012) suggesting its down-regulation and inhibition of apoptosis. The mean IHC score for content of collagen- II and aggrecan at 3 months were higher in PRP Knees (A3) compared to placebo (B3) (Not significant). At 6 months, the Mean IHC Score decreased in both PRP (A6) and Control Knees (B6) for Collagen, but increased for aggrecan compared to its value at 3 months; and this was better in PRP group than in the control (P = 0.024).

CONCLUSION

Multiple injections of PRP has a chondroprotective role by its anti-apoptotic effect and by increasing the aggrecan content in ECM.

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

OBJECTIVE

Given the potential applications of combined biologics, the authors sought to evaluate the in vitro effect of combined platelet-rich plasma (PRP) and hyaluronic acid (HA) on cellular metabolism.

DESIGN

Bone marrow-derived mesenchymal stem cells (BMSCs) and chondrocytes were obtained from the femurs of Sprague-Dawley rats. An inflammatory model was created by adding 10 ng/mL interleukin-1-beta to culture media. Non-crosslinked high-molecular-weight HA, activated-PRP (aPRP), and unactivated-PRP (uPRP) were tested. Cellular proliferation and gene expression were measured at 1 week. Genes of interest included aggrecan, matrix metalloproteinase (MMP)-9, and MMP-13.

RESULTS

Combined uPRP-HA was associated with a significant increase in chondrocyte and BMSC proliferation at numerous preparations. There was a trend of increased chondrocyte aggrecan expression with combined PRP-HA. The greatest and only significant decrease in BMSC MMP-9 expression was observed with combined PRP-HA. While a significant reduction of BMSC MMP-13 expression was seen with PRP and HA-alone, a greater reduction was observed with PRP-HA. MMP-9 chondrocyte expression was significantly reduced in cells treated with PRP-HA. PRP-alone and HA-alone at identical concentrations did not result in a significant reduction. The greatest reduction of MMP-13 chondrocyte expression was observed in chondrocytes plus combined PRP-HA.

CONCLUSIONS

We demonstrated a statistically significant increase in BMSC and chondrocyte proliferation and decreased expression of catabolic enzymes with combined PRP-HA. These results demonstrate the additive in vitro effect of combined PRP-HA to stimulate cellular growth, restore components of the articular extracellular matrix, and reduce inflammation.

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.

Human Platelet Lysate as an Alternative to Autologous Serum for Human Chondrocyte Clinical Use

OBJECTIVE

A pivotal aspect of cartilage tissue engineering resides in cell culture medium supplementation, in view of maximizing in vitro cell proliferation and preserving cellular functionality. Autologous human serum (aHS) is commonly used as an inducive supplement for safe human articular chondrocyte (HAC) proliferation prior to clinical implantation. However, practical clinical use of aHS is hindered by constraining manufacturing requirements and quality assurance-driven downstream processing. The present study investigated potential alternative use of commercial human platelet lysate (hPL) supplements in HAC manufacturing workflows related to clinical therapeutic pathways.

DESIGN

Differential effects of hPL, aHS, and fetal bovine serum were assessed on primary cultured HAC parameters (viability, proliferative rates, and morphology) in 2-dimensional in vitro systems. A 3-dimensional HAC pellet model served for postexpansion assessment of cellular functionality, by visualizing proteoglycan production (Alcian blue staining), and by using qRT-PCR relative quantification of chondrogenic marker (SOX9, COL2-A1, and ACAN) genetic expression.

RESULTS

We found that monolayer HAC culture with hPL or aHS supplements presented similar characteristics (elongated cell morphology and nearly identical growth kinetics). Chondrogenic activity appeared as conserved in HACs expanded with human or bovine supplements, wherein histologic analysis indicated a progressive sGAG accumulation and SOX9, COL2-A1, ACAN gene expression was upregulated in 3-dimensional HAC pellet models.

CONCLUSION

This study therefore supports the use of hPL as a functional equivalent and alternative to aHS for cultured HAC batch preparation, with the potential to effectively alleviate pressure on clinical and manufacturing bottlenecks in cell therapy approaches for cartilage regeneration.

Platelet-rich plasma attenuates interleukin-1β-induced apoptosis and inflammation in chondrocytes through targeting hypoxia-inducible factor-2α

Osteoarthritis (OA) is a prevailing chronic disease in Orthopedics that characterized with severely damaged cartilage and subchondral bone, thus leading to profound disorders of synovial joints. Platelet-rich plasma (PRP) has been applied as a popular non-operative treatment option for promoting musculoskeletal healing. Our previous work demonstrated that PRP protected chondrocytes from interleukin-1β (IL-1β)-induced apoptosis in vitro. However, the underlying mechanism behind the treatment remains unclear. The current study aimed to unveil the molecular signaling underlying its protective role in chondrocytes. Rat chondrocytes were isolated from newborn Sprague Dawley rats and treated with 5 ng/mL IL-1β for 24 h. The expression of hypoxia-inducible factor 2α (HIF-2α) was determined in both mRNA and protein levels. Next, loss- and gain-of-function assays for HIF-2α were performed using small-interfering RNA (siRNA) specific for HIF-2α and adenovirus-mediated HIF-2α overexpression, respectively. In addition, cell apoptosis markers, matrix metalloproteinase (MMP)-1, 3, -9 and -13, and extracellular matrix-related genes were evaluated. Our results demonstrated that IL-1β induced distinct inflammation in chondrocytes. In addition, HIF-2α upregulated in the IL-1β-treated chondrocytes compared to the untreated cells. Interestingly, 10% PRP protected chondrocytes against IL-1β-induced apoptosis and matrix degradation, and meanwhile suppressed the HIF-2α activation. Furthermore, HIF-2α siRNA and HIF-2α overexpression experiments indicated that PRP induced chondroprotection through targeting HIF-2α. Taken together, our findings indicated that PRP attenuates IL-1β-induced chondrocyte apoptosis and inflammation at least partially through inhibiting HIF-2α.

Osteochondral Lesions of the Talus: A Review on Talus Osteochondral Injuries, Including Osteochondritis Dissecans

This is a review on talus osteochondritis dissecans and talus osteochondral lesions. A majority of the osteochondral lesions are associated with trauma while the cause of pure osteochondritis dissecans is still much discussed with a possible cause being repetitive microtraumas associated with vascular disturbances causing subchondral bone necrosis and disability. Symptomatic nondisplaced osteochondral lesions can often be treated conservatively in children and adolescents while such treatment is less successful in adults. Surgical treatment is indicated when there is an unstable cartilage fragment. There are a large number of different operative technique options with no number one technique to be recommended. Most techniques have been presented in level II to IV studies with a low number of patients with short follow ups and few randomized comparisons exist. The actual situation in treating osteochondral lesions in the ankle is presented and discussed.

Evaluation of the influence of platelet-rich plasma (PRP), platelet lysate (PL) and mechanical loading on chondrogenesis in vitro

The aim of this work is to investigate the capability of PRP as an adjuvant therapy to autologous chondrocyte implantation (ACI) in combination with multi-axial load with respect to cartilage regeneration. Articular cartilage shows poor repair capacity and therapies for cartilage defects are still lacking. Well-established operative treatments include ACI, and growing evidence shows the beneficial effects of PRP. Platelets contain numerous growth factors, among them transforming growth factor beta (TGF-β). Dynamic mechanical loading is known to be essential for tissue formation, improving extracellular matrix (ECM) production. For our ACI model monolayer expanded human chondrocytes were seeded into polyurethane scaffolds and embedded in fibrin (hChondro), in PRP-Gel (PRP), or in fibrin with platelet lysate (PL), which was added to the media once a week with a concentration of 50 vol%. The groups were either exposed to static conditions or multi-axial forces in a ball-joint bioreactor for 1 h per day over 2 weeks, mimicking ACI under physiological load. The culture medium was collected and analyzed for glycosaminoglycan (GAG), nitrite and transforming growth factor beta 1 (TGF-β1) content. The cell-scaffold constructs were collected for DNA and GAG quantification; the expression of chondrogenic genes, TGF-β and related receptors, as well as inflammatory genes, were analyzed using qPCR. Loading conditions showed superior chondrogenic differentiation (upregulation of COL2A1, ACAN, COMP and PRG4 expression) than static conditions. PRP and PL groups combined with mechanical loading showed upregulation of COL2A1, ACAN and COMP. The highest amount of total TGF-β1 was quantified in the PL group. Latent TGF-β1 was activated in all loaded groups, while the highest amount was found in the PL group. Load increased TGFBR1/TGFBR2 mRNA ratio, with further increases in response to supplements. In general, loading increased nitrite release into the media. However, over time, the media nitrite content was lower in the PL group compared to the control group. Based on these experiments, we conclude that chondrogenic differentiation is strongest when simulated ACI is performed in combination with dynamic mechanical loading and PRP-gel or PL supplementation. An inflammatory reaction was reduced by PRP and PL, which could be one of the major therapeutic effects. Loading presumably can enhance the action of TGF-β1, which was predominantly activated in loaded PL groups. The combination of load and PRP represents an effective and promising synergy concerning chondrocyte-based cartilage repair.

Google Trends Analysis Shows Increasing Public Interest in Platelet-Rich Plasma Injections for Hip and Knee Osteoarthritis

BACKGROUND

Osteoarthritis is a chronic musculoskeletal condition that frequently affects the hip and knee joints. Given the burden associated with surgical intervention for hip and knee osteoarthritis, patients continue to search for potential nonoperative treatments. One biologic therapy with mixed clinical and basic science evidence for treating osteoarthritis is platelet-rich plasma injections into the affected joint. We used the Google Trends tool to provide a quantitative analysis of national interest in platelet-rich plasma injections for hip and knee osteoarthritis.

METHODS

Google Trends parameters were selected to obtain search data from January 2009 to December 2019. Various combinations of "arthritis," "osteoarthritis," "PRP," "platelet-rich plasma," "knee," and "hip" were entered into the Google Trends tool and trend analyses were performed.

RESULTS

Three linear models were generated to display search volume trends in the United States for platelet-rich plasma and osteoarthritis, hip osteoarthritis, and knee osteoarthritis, respectively. All models showed increased Google queries as time progressed (P < .001), with R² ranging from 0.837 to 0.940. Seasonal, income-related, and geographic variations in public interest in platelet-rich plasma for osteoarthritis were noted.

CONCLUSION

Our results demonstrate a significant rise in Google queries related to platelet-rich plasma injections for osteoarthritis of the hip and knee since 2009. Surgeons treating hip and knee osteoarthritis patients can expect continued interest in platelet-rich plasma, despite inconclusive clinical and basic science data. Trends in public interest may inform patient counseling, shared decision-making, and directions for future clinical research.

Effect of Activated Platelet-Rich Plasma on Chondrogenic Differentiation of Rabbit Bone Marrow-Derived Mesenchymal Stem Cells

We aimed to evaluate the effect of activated platelet-rich plasma (PRP) on proliferation and chondrogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). Six mature male rabbits were included in this study. PRP was obtained by two-step centrifugation from whole blood, and it was activated using CaCl₂ solution. BMSCs were isolated and proliferated from bone marrow of rabbits and characterized by flow cytometry. Passage 3 BMSCs were cultured in high-glucose Dulbecco's modified Eagle's medium (HG-DMEM) with the four different compositions for consecutive 7 days, including 10% fetal bovine serum, 5% PRP, 10% PRP, and 15% PRP. Cell counting assays were performed to evaluate the cell proliferation of BMSCs. BMSCs (5 × 10⁵ cells/well in 6-well plates) were induced in four conditions for 21 days to chondrogenic differentiation evaluation, including commercial chondrogenic medium (control), 5% PRP (HG-DMEM+5% PRP), 10% PRP (HG-DMEM+10% PRP), and 15% PRP (HG-DMEM+15% PRP). The gene expression levels of ACAN, COL2A1, and SOX9 in pellets were detected. Morphological and pathological assessments were performed by the blind observer. After purifying, the percentages of cells with CD105(+)/CD34(-) and CD44(+)/CD45(-) were 96.5% and 92.9%, respectively. The proliferation of BMSCs was enhanced in all groups, and 10% PRP revealed more significant outcome than the others from day 5. The levels of ACAN, COL2A1, and SOX9 were lower in the three PRP groups than control group, but the levels of ACAN and SOX9 were higher in 10% PRP group than 5% and 15% PRP groups. Histological examinations showed that 10% PRP-treated pellets had more regular appearance, larger size, and abundant extracellular matrix than 5% or 10% PRP groups, but still inferior to commercial chondrogenic medium. In conclusion, our results show that PRP may enhance the proliferation of rabbit BMSCs. However, PRP have limited effect on chondrogenic differentiation in comparison with commercial chondrogenic medium in pellets culture.

T2-mapping MRI evaluation of patellofemoral cartilage in patients submitted to intra-articular platelet-rich plasma (PRP) injections

This study evaluated the ability of T2 mapping magnetic resonance imaging at 3 T, in addition to morphological sequences, to assess efficacy of platelet-rich plasma (PRP) injections, characterizing qualitatively and quantitatively the grade of knee cartilage repair in patients with patellofemoral chondropathy. We retrospectively studied 34 patients (22 men, 12 women, mean age 41.8 years, including 22 men) with patellofemoral knee chondropathy, who underwent intra-articular PRP injections and completed a clinical and instrumental follow-up. As control group, we evaluated 34 patients who underwent non-operative therapy. All patients were submitted to clinical (using VAS and WOMAC index) and imaging studies with 3 T magnetic resonance with cartilage analysis with T2 mapping sequences for cartilage analysis before and after treatment. In the study group, mean pre-treatment T2 relaxation time values were 44.2 ± 2.5 ms, considering all articular cartilage compartments, with significant reduction at the follow-up (p < 0.001). At the index compartment, mean pre-treatment T2 relaxation times values were 47.8 ± 3.6 ms, with statistically significant reduction at the follow-up (p < 0.001). Evaluation of focal cartilage lesions reported pre-treatment mean T2 value of 70.1 ± 13.0 ms and post-treatment mean value of 59.9 ± 4.6 ms (p < 0.001). From a clinical point of view, the pre-treatment WOMAC and VAS scores were 18.3 ± 4.5 and 7 (IQR:6-7.2), respectively; the post-treatment values were 7.3 ± 3.2 and 2 (IQR: 1.7-3.0), respectively (p < 0.001). In the control group, despite clinical improvement, we didn't find significant T2 values change during the follow-up period. In conclusion, T2 mapping is a valuable indicator for chondropathy and treatment-related changes over time.

Optimization of Lyophilized Hyperacute Serum (HAS) as a Regenerative Therapeutic in Osteoarthritis

Hyperacute serum (HAS) is a blood derivative product that promotes the proliferation of various cell types and controls inflammation in vitro. The aim of this study is to investigate the regenerative potential of different formulations of HAS, including lyophilized and hyaluronic acid combined versions, to obtain a stable and standardized therapeutic in osteoarthritis (OA), which may be able to overcome the variability limitations of platelet-rich plasma (PRP). Primary human osteoarthritic chondrocytes were used for testing cellular viability and gene expression of OA-related genes. Moreover, a co-culture of human explants of cartilage, bone and synovium under inflammatory conditions was used for investigating the inflammatory control capacities of the different therapeutics. In this study, one formulation of lyophilized HAS achieved the high cell viability rates of liquid HAS and PRP. Gene expression analysis showed that HAS induced higher Col1a1 expression than PRP. Cytokine quantification from supernatant fluids revealed that HAS treatment of inflamed co-cultures significantly reduced levels of IL-5, IL-15, IL-2, TNFα, IL-7 and IL-12. To conclude, lyophilized HAS is a stable and standardized therapeutic with high potential in joint regeneration.

Mechanisms of Action and Efficacy of Hyaluronic Acid, Corticosteroids and Platelet-Rich Plasma in the Treatment of Temporomandibular Joint Osteoarthritis-A Systematic Review

Temporomandibular joint osteoarthritis (TMJ OA) is a low-inflammatory disorder with multifactorial etiology. The aim of this review was to present the current state of knowledge regarding the mechanisms of action and the efficacy of hyaluronic acid (HA), corticosteroids (CS) and platelet-rich plasma (PRP) in the treatment of TMJ OA.: The PubMed database was analyzed with the keywords: "(temporomandibular joint) AND ((osteoarthritis) OR (dysfunction) OR (disorders) OR (pain)) AND ((treatment) OR (arthrocentesis) OR (arthroscopy) OR (injection)) AND ((hyaluronic acid) OR (corticosteroid) OR (platelet rich plasma))". After screening of 363 results, 16 studies were included in this review. Arthrocentesis alone effectively reduces pain and improves jaw function in patients diagnosed with TMJ OA. Additional injections of HA, either low-molecular-weight (LMW) HA or high-molecular-weight (HMW) HA, or CS at the end of the arthrocentesis do not improve the final clinical outcomes. CS present several negative effects on the articular cartilage. Results related to additional PRP injections are not consistent and are rather questionable. Further studies should be multicenter, based on a larger group of patients and should answer the question of whether other methods of TMJ OA treatment are more beneficial for the patients than simple arthrocentesis.

Effects of Extracellular Vesicles from Blood-Derived Products on Osteoarthritic Chondrocytes within an Inflammation Model

Osteoarthritis (OA) is hallmarked by a progressive degradation of articular cartilage. One major driver of OA is inflammation, in which cytokines such as IL-6, TNF-α and IL-1β are secreted by activated chondrocytes, as well as synovial cells—including macrophages. Intra-articular injection of blood products—such as citrate-anticoagulated plasma (CPRP), hyperacute serum (hypACT), and extracellular vesicles (EVs) isolated from blood products—is gaining increasing importance in regenerative medicine for the treatment of OA. A co-culture system of primary OA chondrocytes and activated M1 macrophages was developed to model an OA joint in order to observe the effects of EVs in modulating the inflammatory environment. Primary OA chondrocytes were obtained from patients undergoing total knee replacement. Primary monocytes obtained from voluntary healthy donors and the monocytic cell line THP-1 were differentiated and activated into proinflammatory M1 macrophages. EVs were isolated by ultracentrifugation and characterized by nanoparticle tracking analysis and Western blot. Gene expression analysis of chondrocytes by RT-qPCR revealed increased type II collagen expression, while cytokine profiling via ELISA showed lower TNF-α and IL-1β levels associated with EV treatment. In conclusion, the inflammation model provides an accessible tool to investigate the effects of blood products and EVs in the inflammatory context of OA.

Evaluation of Arthrocentesis with and Without Platelet-Rich Plasma in the Management of Internal Derangement of Temporomandibular Joint: A Randomized Controlled Trial

PURPOSE

The purpose of this study was to compare the efficacy of intra-articular injection of platelet-rich plasma after arthrocentesis versus arthrocentesis alone as a treatment modality in patients with internal derangement of temporomandibular joint.

METHODS

Twenty-four patients suffering from internal derangement of temporomandibular joint were included in the study. The patients were randomly divided into two groups as follows-twelve patients underwent arthrocentesis followed by intra-articular injection of platelet-rich plasma (study group) and the other twelve were treated by arthrocentesis alone (control group). Pain intensity was recorded on visual analogue scale (VAS); maximum mouth opening and joint sound were measured before and after intervention. The patients were clinically evaluated at the intervals of 1 month, 3 and 6 months subsequently.

RESULTS

There was no statistically significant difference in all the parameters between the groups. Intra-group analysis showed statistically significant improvement in all the parameters.

CONCLUSION

In both groups, improvement of pain, maximum mouth opening and TMJ sound were observed at all intervals, but there was no statistically significant improvement in arthrocentesis with PRP group when compared with arthrocentesis alone.

Intervertebral Disc Degeneration: The Role and Evidence for Non-Stem-Cell-Based Regenerative Therapies

The use of non-stem-cell-based regenerative medicine therapies for lumbar discogenic pain is an area of growing interest. Although the intervertebral disc is a largely avascular structure, cells located within the nucleus pulposus as well as annulus fibrosis could be targeted for regenerative and restorative treatments. Degenerative disc disease is caused by an imbalance of catabolic and anabolic events within the nucleus pulposus. As catabolic processes overwhelm the environment within the nucleus pulposus, proinflammatory cytokines increase in concentration and lead to further disc degeneration. Non-stem-cell-based therapies, which include growth factor therapy and other proteins, can lead to an increased production of collagen and proteoglycans within the disc.

Applications of Biocompatible Scaffold Materials in Stem Cell-Based Cartilage Tissue Engineering

Cartilage, especially articular cartilage, is a unique connective tissue consisting of chondrocytes and cartilage matrix that covers the surface of joints. It plays a critical role in maintaining joint durability and mobility by providing nearly frictionless articulation for mechanical load transmission between joints. Damage to the articular cartilage frequently results from sport-related injuries, systemic diseases, degeneration, trauma, or tumors. Failure to treat impaired cartilage may lead to osteoarthritis, affecting more than 25% of the adult population globally. Articular cartilage has a very low intrinsic self-repair capacity due to the limited proliferative ability of adult chondrocytes, lack of vascularization and innervation, slow matrix turnover, and low supply of progenitor cells. Furthermore, articular chondrocytes are encapsulated in low-nutrient, low-oxygen environment. While cartilage restoration techniques such as osteochondral transplantation, autologous chondrocyte implantation (ACI), and microfracture have been used to repair certain cartilage defects, the clinical outcomes are often mixed and undesirable. Cartilage tissue engineering (CTE) may hold promise to facilitate cartilage repair. Ideally, the prerequisites for successful CTE should include the use of effective chondrogenic factors, an ample supply of chondrogenic progenitors, and the employment of cell-friendly, biocompatible scaffold materials. Significant progress has been made on the above three fronts in past decade, which has been further facilitated by the advent of 3D bio-printing. In this review, we briefly discuss potential sources of chondrogenic progenitors. We then primarily focus on currently available chondrocyte-friendly scaffold materials, along with 3D bioprinting techniques, for their potential roles in effective CTE. It is hoped that this review will serve as a primer to bring cartilage biologists, synthetic chemists, biomechanical engineers, and 3D-bioprinting technologists together to expedite CTE process for eventual clinical applications.

Potential Mechanism of Action of Current Point-of-Care Autologous Therapy Treatments for Osteoarthritis of the Knee-A Narrative Review

Osteoarthritis (OA) is a progressive degenerative disease that manifests as pain and inflammation and often results in total joint replacement. There is significant interest in understanding how intra-articular injections made from autologous blood or bone marrow could alleviate symptoms and potentially intervene in the progression of the disease. There is in vitro an in vivo evidence that suggests that these therapies, including platelet-rich plasma (PRP), autologous anti-inflammatories (AAIs), and concentrated bone marrow aspirate (cBMA), can interrupt cartilage matrix degradation driven by pro-inflammatory cytokines. This review analyzes the evidence for and against inclusion of white blood cells, the potential role of platelets, and the less studied potential role of blood plasma when combining these components to create an autologous point-of-care therapy to treat OA. There has been significant focus on the differences between the various autologous therapies. However, evidence suggests that there may be more in common between groups and perhaps we should be thinking of these therapies on a spectrum of the same technology, each providing significant levels of anti-inflammatory cytokines that can be antagonists against the inflammatory cytokines driving OA symptoms and progression. While clinical data have demonstrated symptom alleviation, more studies will need to be conducted to determine whether these preclinical disease-modifying findings translate into clinical practice.

Platelet-rich plasma as an effective biological therapy in early-stage knee osteoarthritis: One year follow up

Objective: PRP is produced by centrifugation of whole blood containing highly concentrated platelets, associated growth factors, and other bioactive agents which has been shown to provide some symptomatic relief in early knee osteoarthritis (OA). The principal objective of our study was to evaluate the effectiveness and safety of standardized intra-articular injection of autologous PRP in early osteoarthritis knee. Methods: A total of 98 eligible symptomatic patients received two injections of standardized PRP 3 weeks apart. Clinical outcomes were evaluated using the VAS and Western Ontario and McMaster Universities Arthritis Index (WOMAC) questionnaire before treatment and at 6 weeks, 3 months, 6 months, and 1 year after treatment. Secondary objectives were safety (side effects), and the effect of PRP on the different grades of knee degeneration. Results: There was a statistically significant improvement in mean VAS and WOMAC scores at 6 weeks, 3 months, 6 months, and slight loss of improvement at 1 year follow-up. There was also a correlation between the degree of degeneration and improvement in the mean scores. The decrease in mean pain score is more in grades 1 and 2 (early OA) than in grade 3. The intraarticular injection is safe, with no major complications. Conclusion: PRP is a safe and effective biological regenerative therapy for early OA Knees. It provides a significant clinical improvement in patients with some loss of improvement with time. More studies will be needed to confirm our findings.

The effectiveness of platelet-rich plasma gel on full-thickness cartilage defect repair in a rabbit model

AIMS

The present study investigates the effectiveness of platelet-rich plasma (PRP) gel without adjunct to induce cartilage regeneration in large osteochondral defects in a rabbit model.

METHODS

A bilateral osteochondral defect was created in the femoral trochlear groove of 14 New Zealand white rabbits. The right knees were filled with PRP gel and the contralateral knees remained untreated and served as control sides. Some animals were killed at week 3 and others at week 12 postoperatively. The joints were harvested and assessed by Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) MRI scoring system, and examined using the International Cartilage Repair Society (ICRS) macroscopic and ICRS histological scoring systems. Additionally, the collagen type II content was evaluated by the immunohistochemical staining.

RESULTS

After 12 weeks post-surgery, the defects of the PRP group were repaired by hyaline cartilage-like tissue. However, incomplete cartilage regeneration was observed in the PRP group for three weeks. The control groups showed fibrocartilaginous or fibrous tissue, respectively, at each timepoint.

CONCLUSION

Our study proved that the use of PRP gel without any adjuncts could successfully produce a good healing response and resurface the osteochondral defect with a better quality of cartilage in a rabbit model. Cite this article: Bone Joint Res 2021;10(3):192-202.

Targeting Cartilage Degradation in Osteoarthritis

Osteoarthritis is a common, degenerative joint disease with significant socio-economic impact worldwide. There are currently no disease-modifying drugs available to treat the disease, making this an important area of pharmaceutical research. In this review, we assessed approaches being explored to directly inhibit metalloproteinase-mediated cartilage degradation and to counteract cartilage damage by promoting growth factor-driven repair. Metalloproteinase-blocking antibodies are discussed, along with recent clinical trials on FGF18 and Wnt pathway inhibitors. We also considered dendrimer-based approaches being developed to deliver and retain such therapeutics in the joint environment. These may reduce systemic side effects while improving local half-life and concentration. Development of such targeted anabolic therapies would be of great benefit in the osteoarthritis field.

Feasibility of Human Platelet Lysate as an Alternative to Foetal Bovine Serum for In Vitro Expansion of Chondrocytes

Osteoarthritis (OA) is a degenerative joint disease that affects a lot of people worldwide. Current treatment for OA mainly focuses on halting or slowing down the disease progress and to improve the patient’s quality of life and functionality. Autologous chondrocyte implantation (ACI) is a new treatment modality with the potential to promote regeneration of worn cartilage. Traditionally, foetal bovine serum (FBS) is used to expand the chondrocytes. However, the use of FBS is not ideal for the expansion of cells mean for clinical applications as it possesses the risk of animal pathogen transmission and animal protein transfer to host. Human platelet lysate (HPL) appears to be a suitable alternative to FBS as it is rich in biological factors that enhance cell proliferation. Thus far, HPL has been found to be superior in promoting chondrocyte proliferation compared to FBS. However, both HPL and FBS cannot prevent chondrocyte dedifferentiation. Discrepant results have been reported for the maintenance of chondrocyte redifferentiation potential by HPL. These differences are likely due to the diversity in the HPL preparation methods. In the future, more studies on HPL need to be performed to develop a standardized technique which is capable of producing HPL that can maintain the chondrocyte redifferentiation potential reproducibly. This review discusses the in vitro expansion of chondrocytes with FBS and HPL, focusing on its capability to promote the proliferation and maintain the chondrogenic characteristics of chondrocytes.

Effect of Platelet-Rich Plasma on Intervertebral Disc Degeneration In Vivo and In Vitro: A Critical Review

Intervertebral disc degeneration (IDD) is a globally occurring disease that represents a significant cause of socioeconomic problems. Currently, the main method for treating IDD is surgery, including discectomy and vertebral fusion. Several in vitro experiments demonstrated that platelet-rich plasma (PRP) could stimulate cell proliferation and extracellular matrix regeneration. Additionally, in vivo experiments have proven that PRP injection could restore intervertebral disc height. Clinical studies demonstrated that PRP injection could significantly relieve patient pain. However, further studies are still required to clarify the roles of PRP in IDD prevention and treatment. This review is aimed at summarizing and critically analyzing the current evidence regarding IDD treatment with PRP.

Effectiveness of platelet-rich plasma in the management of hip osteoarthritis: a systematic review and meta-analysis

The effectiveness of platelet-rich plasma (PRP) injections for osteoarthritis (OA) is still controversial. Previous research supports the use of intra-articular PRP injections to promote a favorable environment for joint tissue healing and to delay the progression of OA. The purpose of this review is to investigate the effectiveness of PRP in the management of hip osteoarthritis (HOA). Five electronic databases were searched from inception to May 2019: Medline (via PubMed), SportDiscus via EBSCO, ProQuest Health & Medical Complete, CINAHL, and Cochrane. Risk of bias was assessed with the Cochrane risk of bias tool. The GRADE method was used to assess the level of evidence for the studies included in this review. Clinical trials evaluate PRP injections among adult patients diagnosed with HOA according to the American College of Rheumatology criteria. At least one outcome measure for pain or function must have been reported. A total of 4 trials (334 participants, 340 hips) were included, all marked as "moderate risk of bias". Pain and function were assessed throughout the studies with visual analogue scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Harris Hip Score (HHS) tools. Intra-articular PRP injections were more effective at stages earlier than 3 months for both treatment groups with the exception of WOMAC score in one study. The superiority of PRP against comparative treatments was only reported in one study; longer-term evaluations from 4 to 12 months showed diverse results, with only one study reporting significantly better results for PRP. PRP may be beneficial and safe for patients with HOA at mid-term follow-up. However, its superiority over other procedures such as hyaluronic acid remains unclear. Further researches with high-quality designs and larger samples become imperative.