Platelet-rich plasma shows beneficial effects for patients with knee osteoarthritis by suppressing inflammatory factors

Optimal Dosage of Platelet-Rich Plasma Injections in Patients With Osteoarthritis of the Knee: A Scoping Review

Knee osteoarthritis (KOA) is a healthcare burden affecting over 595 million people worldwide. Recently, intra-articular platelet-rich plasma (PRP) injections from the patient's blood have shown promise in slowing KOA progression due to platelets' regenerative properties. This study aimed to evaluate the optimal dosing and schedule for PRP therapy in managing mild to moderate KOA. A systematic search was conducted across Embase, Ovid Medline, Web of Science, Cochrane Central, and CINAHL using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify articles published from August 2015 to March 2024. Keywords included "platelet rich plasma," "knee osteoarthritis," and "administration schedule." Inclusion criteria were studies on human patients utilizing PRP as monotherapy in experimental trials, while review articles, editorials, case reports, and meta-analyses were excluded. Three reviewers independently extracted and described patient interventions and outcomes, focusing on Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Visual Analog Scale (VAS), and imaging changes. Thirty-nine publications with PRP monotherapy protocols were found, with fourteen meeting the inclusion criteria. Twelve studies were randomized clinical trials, and two were longitudinal cohort studies, totaling 1704 patients with a mean follow-up of 7.51 ± 4.82 months. The most common PRP protocol was 4.357 ± 1.419 mL infusions, with three doses every four weeks and a single dose being frequent. Platelet values varied, with seven including a mean platelet count, three reporting that the platelet concentration in each dose had to be at least 150,000/μL, and four did not include platelet concentration. There was notable variation in PRP acquisition protocols, blood volume, and centrifugation processes across studies. Therapeutic benefits were represented by WOMAC and VAS scores rather than imaging changes. PRP injections appear to be safe and effective for symptomatic relief of knee pain associated with mild to moderate osteoarthritis (OA). The average infusion volume was 4 mL, administered at three doses four weeks apart. Given that platelet-derived growth factors promote the proliferation of chondrocytes and mesenchymal stem cells, leading to the stimulation of articular cartilage remodeling, further studies are warranted to assess the optimal platelet count necessary for the long-term effects of PRP in knee cartilage healing and sustained symptomatic improvement.

Comparison of the short-term effect of intra-articular hyaluronic acid and platelet-rich plasma injections in knee osteoarthritis: a randomized clinical trial

Introduction

Osteoarthritis (OA) is one of the most common degenerative joint diseases which involved all joints. It is very important to choose a treatment method with high efficiency to reduce the pain and disability of patients and also to improve their quality of life. The current study aimed to investigate the therapeutic effects of intra-articular injection of PRP and hyaluronic acid (HA) in the knee of people with knee osteoarthritis (KOA).

Methods

In this randomized clinical trial study, 90 patients with KOA were randomly divided into two groups of intra-articular HA and PRP. The patients of the two groups were followed up for five months and different outcomes were recorded. The McMaster index (WOMAC) evaluated all patients at rest and during movements. Measurements were taken at the beginning and after the third month of follow-up.

Results

Three month after the last injection (5th month) and after adjusting of baseline value using analysis of covariance, the mean of knee pain, stiffness, physical function and finally total score in the PRP group, was significantly lower than the HA group. Regarding the Osteoarthritis grade, the mean of knee pain, Stiffness, Physical function and finally total score in the PRP group was significantly lower than the HA group in all Osteoarthritis grades. Also, there were no complications in the studied groups.

Conclusions

The results of the current study showed that pain and stiffness reduction as well as physical function of the knee joint in the PRP group was better than in the HA group.

Is there a role for platelet rich plasma injection in vulvar lichen sclerosus? A self-controlled pilot study

BACKGROUND

Owing to the evidence that as many as 30-40% of patients with vulvar lichen sclerosus (VLS) fail to report a remission of symptoms with first-line corticosteroid treatment (TCS), especially as what regards dyspareunia, we aimed to analyze patients' satisfaction following vulvar injection of autologous platelet-rich plasma (PRP). This is intended as an adjunctive treatment, to be used following TCS, and appears to promote tissue repair. It may also possibly have immunomodulatory proprieties.

MATERIALS AND METHODS

Patients with VLS were considered eligible for this pilot study if, despite having been treated with a 3-month TCS regimen, they reported a persistence of symptoms. PRP was produced in a referral center using a manual method and a standardized protocol. Each patient received three treatments 4 to 6 weeks apart.

RESULTS

A total of 50 patients with a median age of 53 years [IQR 38-59 years] were included in the study. 6 months after the last injection of PRP all patients were either satisfied or very satisfied with the treatment (100%; 95% CI 93-100%). Median NRS scores for itching, burning, dyspareunia and dysuria were significantly reduced (p < 0.05) and FSFI, HADS and SF-12 questionnaires revealed a significant improvement in sexual function, psychological wellbeing and quality of life (p < 0.05). The number of patients reporting the need for maintenance TCS treatment was reduced by 42% (p < 0.001) and an improvement in vulvar elasticity and color was reported in all patients.

CONCLUSION

Following standard medical therapy, PRP may be effective not only in improving symptoms, but also in restoring function.

Long term improvement of knee osteoarthritis after injection of single high/very high volume of very pure PRP: A retrospective analysis of patients optimally managed in dedicated centers

Introduction

PRP is gaining increasing interest for pain relief and improvement of joint function in patients with knee osteoarthritis (KOA) but practices and results remain heterogeneous limiting its adoption as standard of care. Current international recommendations are to collect real-life evidence of efficacy with a systematic monitoring of PRP quality and patients' outcomes. We aimed to analyze the response of patients presenting KOA and treated with standardized PRP injection in routine care. We also investigated the potential contributing factors including patient's phenotype and PRP characteristics.

Methods

Patients with symptomatic KOA and that failed first-line therapy received a single injection of a qualified PRP prepared using medical devices allowing to recover a high/very high volume of very pure PRP. Visual analogue scale (VAS) and Western Ontario and McMaster Osteoarthritis Index (WOMAC) score were recorded at baseline and during 18 months follow-up.

Results

431 patients had available follow-up data at 3 months, 291 at 6 months, 137 at 12 months and 44 at 18 months. PRP induced a significant decrease of WOMAC score at all follow up endpoints (29.2 ± 19.2 at 3 months, p < 0.001 and 25.9 ± 19.7 at 12 months, p < 0.01, compared to 39.7 ± 18.9 at baseline). Similar results were observed for pain VAS (38.9 ± 23.3 at 3 months, p < 0.001 and 35.3 ± 24.1 at 12 months, p < 0.05, compared to 56.0 ± 20.7 at baseline). Changes at 12 months were correlated to baseline scores and to the level of improvement at 3 months. The proportion of OMERACT OARSI responders reached 56.2 % for the total cohort and 60.4 % for severe patients at 6 months. Treatment failure occurred for 8.4 % of patients. Age, BMI or Kellgren-Lawrence grade did not impact on efficacy.

Conclusion

This real-life study evidences the clinical benefit of a standardized high or very high-volume injection of very pure PRP in patients with KOA, including those with a severe grade. It opens perspectives in the positioning of such strategy to delay arthroplasty and provide insights on factors able to anticipate long term efficacy.

Efficacy and safety of corticosteroids, hyaluronic acid, and PRP and combination therapy for knee osteoarthritis: a systematic review and network meta-analysis

OBJECTIVE

There are many injectable treatments for knee osteoarthritis with different characteristics and effects, the aim is to understand which one can lead to better and safer results.

METHODS

The PRISMA principles were followed when doing the literature search. Web of Science databases, Embase, the Cochrane Library, PubMed, and the Wanfang database were searched to identified randomized controlled trials that assessed the efficacy of corticosteroids (CSC), platelet-rich plasma (PRP), hyaluronic acid (HA), and combination therapy in treating KOA. Risk of bias was assessed using the relevant Cochrane tools (version 1.0). The outcome measure included the visual analog scale (VAS) score, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score, and treatment-related adverse events. The network meta-analysis was performed using STATA17 software and a Bayesian stratified random effects model.

RESULTS

Network meta-analysis using the Bayesian random-effects model revealed 35 studies with 3104 participants. PRP showed the best WOMAC score at a 3-month follow-up, followed by PRP + HA, HA, placebo, and CSC; PRP + HA scored the highest VAS, followed by PRP, CSC, HA, and placebo. PRP, CSC, HA, and placebo had the highest WOMAC scores six months following treatment; PRP + HA showed the best VAS scores. PRP showed the best WOMAC score at 12 months, followed by PRP + HA, HA, placebo, and CSC; The best VAS score was obtained with PRP, followed by PRP + HA, HA, and CSC. No therapy demonstrated a rise in adverse events linked to the treatment in terms of safety.

CONCLUSIONS

The current study found that PRP and PRP + HA were the most successful in improving function and alleviating pain after 3, 6, and 12 months of follow-up. CSC, HA, PRP, and combination therapy did not result in an increase in the incidence of treatment-related side events as compared to placebo.

Platelet-Rich Plasma Treatment for Chronic Respiratory Disease

This study was conducted to test the hypothesis that platelet-rich plasma (PRP) therapy in chronic respiratory disease patients will cause lung regeneration, thereby slowing the progression of the disease. We performed a search to obtain pertinent articles on the following electronic databases: Google Scholar, PubMed, NCBI, Medscape, and clinicaltrials.gov. Keywords used during in search included "Platelet Rich Plasma" AND "Chronic Respiratory Disease" AND/OR "Chronic Obstructive Pulmonary Disease". A total of 15 articles were chosen for this paper, published from 2011 to 2021, and included case series, lab studies, animal studies, cohort studies, and clinical trials. All statistical data were considered significant if the p-value was less than 5%, or 0.05. Our findings confirmed that PRP therapy successfully caused anti-inflammatory effects and acceleration of tissue regeneration, resulting in improved lung function. This, in turn, slowed the progression of the disease and led to an improved quality of life. Not all chronic respiratory disease patients present in the same manner, but the connecting link is the damaged tissue of the lungs, causing issues with the functionality of the lungs. By adjunctively treating patients with PRP, the high concentration of platelets and their secreted growth factors can help induce an acceleration of healing and regeneration of pulmonary tissue. This, in turn, can slow the progression of the disease, which could lower the overall mortality rate in chronic respiratory disease patients. More studies should be conducted on this topic, specifically large, double-blinded, randomized human trials with controls, to further assess the efficacy and beneficial effects of PRP treatment on the lungs.

Stored whole blood transfusion initiates serum amyloid A activation monitored by real-time dynamic imaging

BACKGROUND

Transfusion of stored whole blood (SWB) to resuscitate severe traumatic haemorrhage patients in military operations and civilian emergency centres is being increasingly used in routine practice. It has been well established that transfusion of red blood cells (RBCs) after prolonged storage has harmful effects, mainly mediated by inflammation. Whether the side effects of inflammation are brought about by SWB transfusion remains unclear.

MATERIALS AND METHODS

A hepatocyte SAA (serum amyloid A) specific reporter mouse that facilitated non-invasive imaging of hepatocyte SAA expression was used to evaluate acute inflammation and acute-phase reaction after the transfusion of SWB or components separated from end-storage whole blood. The whole blood of C57BL/6 donor mouse was used to model an allogeneic transfusion to BALB/c recipient mouse.

RESULTS

End-storage whole blood (14 days of storage) transfusion induced the most significant SAA expression, while 10-day storage resulted in a much weaker signal compared to their fresh and 5-day storage counterparts. RBCs rather than white blood cells and plasma-containing platelets are thought to be responsible for the systemic inflammatory and SAA activation during end-storage whole blood transfusion. Circulatory and hepatic pro-inflammatory cytokines secreted by M1-polarised macrophage initiated the SAA expression in hepatocytes through nuclear transcription factor NF-κB.

DISCUSSION

Storage lesions will also occur during the storage of whole blood, which is related to the change in RBCs with prolonged storage. The side effect induced by systemic inflammation and acute-phase reaction should be considered before resuscitation with long-term storage whole blood transfusion.

The Influence of Body Mass Index on Growth Factor Composition in the Platelet-Rich Plasma in Patients with Knee Osteoarthritis

BACKGROUND

An abnormally high body mass index is strongly associated with knee osteoarthritis. Usually, obese patients are excluded from clinical trials involving PRP intra-articular injections. Growth factors have been demonstrated to have a disease-modifying effect on KOA treatment, even though data on their influence on treatment effectiveness in obese patients are lacking.

PURPOSE

To prospectively compare the level of selected growth factors including transforming growth factor-b (TGF-β), epidermal growth factor (EGF), fibroblast growth factor, insulin-like growth factor-1 (IGF-1), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and fibroblast growth factor-2 (FGF-2) in platelet-rich plasma (PRP) in obese patients and patients with normal BMI.

METHODS

A total of 49 patients were included in the study according to inclusion and exclusion criteria. The groups strongly differed in body mass index (median values 21.6 vs. 32.15). Concentrations of growth factors were measured with an enzyme-linked immunosorbent assay. Statistical significance was determined with the Mann-Whitney U test. The compliance of the distribution of the results with the normal distribution was checked using the Shapiro-Wilk test separately for both groups.

RESULTS

There were no statistically significant differences in median marker levels between groups. Statistically significant Pearson correlations were observed between IGF-1 serum level and age (weak negative, r = -0.294, p = 0.041) and gender (moderate positive, r = 0.392, 0.005).

CONCLUSIONS

BMI does not influence the level of selected growth factors in patients with knee osteoarthritis. Obese and non-obese patients had similar compositions of PDGF, TGF-β, EGF, FGF-2, IGF-1, and VEGF. PRP can be used in both groups with similar effects associated with growth factors' influence on articular cartilage.

Osteotomies and Total Knee Arthroplasty: Systematic Review and Meta-Analysis

Total knee replacement (TKA) is a frequent modality performed in patients with osteoarthritis. Specific circumstances can make it much more difficult to execute successfully, and additional procedures such as osteotomy may be required. The aim of this study was to perform a meta-analysis and systematic review of osteotomies combined with TKA.

METHODS

In June 2022, a search PubMed, Embase, Cochrane, and Clinicaltrials was undertaken, adhering to PRISMA guidelines. The search included the terms "osteotomy" and "total knee arthroplasty".

RESULTS

Two subgroups (tibial tubercle osteotomy and medial femoral condyle osteotomy) were included in the meta-analysis. Further subgroups were described as a narrative review. The primary outcome showed no significant difference in favor to TTO. Secondary outcomes showed improved results in all presented subgroups compared to preoperative status.

CONCLUSION

This study showed a significant deficit of randomized control trials treated with osteotomies, in addition to TKA, and a lack of evidence-based surgical guidelines for the treatment of patients with OA in special conditions: posttraumatic deformities, stiff knee, severe varus, and valgus axis or patella disorders.

Activated Serum Increases In Vitro Cellular Proliferation and Growth Factor Expression of Musculoskeletal Cells

The purpose of this study was to investigate proteomic alteration that occurs to whole blood when converted to activated serum (AS) using an autologous thrombin system. This study further sought to evaluate the functional in vitro effect of AS on tenocytes, chondrocytes, subacromial bursal cells, and osteoblasts. The peptide/protein composition of AS was analyzed by liquid chromatography−mass spectrophotometry (LC-MS). The cell lines were treated with AS, and cellular proliferation was quantified 48 h after treatment. Platelet-derived growth factor (PDGF), insulin-like growth factor 1 (IGF-1), vascular endothelial growth factor (VEGF), interleukin-1 beta (IL-1β), and interleukin-1 receptor antagonist (IL-1Ra) were quantified utilizing enzyme-linked immunosorbent assays (ELISAs). LC-MS identified 357 proteins across the AS and whole blood. Fifty-four of the proteins identified had significant differences between the relative protein abundance of the AS samples compared to whole blood. Treatment with AS in all cell lines significantly increased proliferation compared to control cells at 48 h. Increased PDGF, VEGF, and IGF-1 in all cell lines exposed to AS compared to the control (p < 0.05) were observed. These findings suggest that treatment with AS increases in vitro cellular proliferation and the release of growth factors that may play a role in tissue repair.

Intra-Articular Injection of Platelet-Rich Plasma Is More Effective than Hyaluronic Acid or Steroid Injection in the Treatment of Mild to Moderate Knee Osteoarthritis: A Prospective, Randomized, Triple-Parallel Clinical Trial

Purpose: To prospectively compare the efficacy and safety of intra-articular injections of platelet-rich plasma (PRP) with hyaluronic acid (HA) and glucocorticosteroid (CS) control groups for knee osteoarthritis (KOA) in a randomized, triple-parallel, single-center clinical trial. Methods: A total of 75 patients were randomly assigned to one of three groups receiving a single injection of either leukocyte-poor platelet-rich plasma (25 knees), hyaluronic acid (25 knees), or glucocorticosteroid (25 knees). The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score was collected at baseline and 6, 12, and 26 weeks after treatment. Results: After 6 weeks of PRP administration, a decrease in the mean WOMAC value was observed in all three study groups. Three months after administration, the greatest decrease in the mean WOMAC value was obtained in the PRP group. The results in the HA and CS groups were similar (p = 0.681). In the one-way analysis of variance and post hoc analysis using the HSD Tukey test, a significantly greater improvement was shown by comparing the PRP and CS groups (p = 0.001), and the PRP and HA groups (p = 0.010). After intra-articular injection of CS, the reduction in pain was greatest 6 weeks after administration, and the mean value was the lowest among all groups. During subsequent visits, the value of the pain subscale increased, and after 6 months, it was the highest among the studied groups. Using the Wilcoxon paired test, no PRP effect was found to reduce stiffness at the 6-month follow-up (p = 0.908). Functional improvement was achieved in all groups, i.e., a decrease in the value of this subscale 6 months after administration. The largest decrease was seen in the group that received PRP (p < 0.001) and then in the HA group. The smallest decrease among the investigated methods was shown in the CS group. Conclusions: Intra-articular injections of PRP can provide clinically significant functional improvement for at least 6 months in patients with mild to moderate KOA which is superior to HA or CS injections.

Role of Platelets in Osteoarthritis-Updated Systematic Review and Meta-Analysis on the Role of Platelet-Rich Plasma in Osteoarthritis

Platelets are an essential component of hemostasis, with an increasing role in host inflammatory processes in injured tissues. The reaction between receptors and vascular endothelial cells results in the recruitment of platelets in the immune response pathway. The aim of the present review is to describe the role of platelets in osteoarthritis. Platelets induce secretion of biological substances, many of which are key players in the inflammatory response in osteoarthritis. Molecules involved in cartilage degeneration, or being markers of inflammation in osteoarthritis, are cytokines, such as tumor necrosis factor α (TNFα), interleukins (IL), type II collagen, aggrecan, and metalloproteinases. Surprisingly, platelets may also be used as a treatment modality for osteoarthritis. Multiple randomized controlled trials included in our systematic review and meta-analyses prove the effectiveness of platelet-rich plasma (PRP) as a minimally invasive method of pain alleviation in osteoarthritis treatment.

Bladder Ultrastructure and Urinary Cytokine Abnormality in Patients with Recurrent Urinary Tract Infection and the Changes after Intravesical Platelet-Rich Plasma Injections

This study investigates the bladder from patients with recurrent urinary tract infection (rUTI) at baseline and after intravesical platelet-rich plasma (PRP) injections. Patients with rUTI who underwent repeated intravesical PRP injections provided bladder and urine specimens at baseline and after treatment. Bladder specimens were investigated with electron microscopy and Western blotting. The urine sample was analyzed with commercially available Milliplex immunoassays. A total of 29 patients were enrolled. At baseline, the rUTI bladders exhibited defects of integrity in umbrella cells, a widened tight junction, and lysed organelles. Intracellular bacterial community incubations in the epithelial cells were also noted. Improvement in bladder defects after PRP injection was noted in 25–42% of patients. Bladder UPK3 expression was significantly lower in the patients with rUTI than in controls. Baseline levels of urinary inflammatory cytokine interleukin (IL)-6, IL-8, and brain-derived neurotrophic factor were higher in the patients with rUTI than in the controls, but there were lower levels of vascular endothelial growth factor and nerve growth factor. In the patients with rUTI who recovered from acute infection, the bladders still had immature urothelium, various ultrastructural defects, and elevated urinary inflammatory cytokines. PRP injection has the potential to promote bladder recovery in some of these patients.

The Effect of Platelet-Rich Plasma on the Intra-Articular Microenvironment in Knee Osteoarthritis

Knee osteoarthritis (KOA) represents a clinical challenge due to poor potential for spontaneous healing of cartilage lesions. Several treatment options are available for KOA, including oral nonsteroidal anti-inflammatory drugs, physical therapy, braces, activity modification, and finally operative treatment. Intra-articular (IA) injections are usually used when the non-operative treatment is not effective, and when the surgery is not yet indicated. More and more studies suggesting that IA injections are as or even more efficient and safe than NSAIDs. Recently, research to improve intra-articular homeostasis has focused on biologic adjuncts, such as platelet-rich plasma (PRP). The catabolic and inflammatory intra-articular processes that exists in knee osteoarthritis (KOA) may be influenced by the administration of PRP and its derivatives. PRP can induce a regenerative response and lead to the improvement of metabolic functions of damaged structures. However, the positive effect on chondrogenesis and proliferation of mesenchymal stem cells (MSC) is still highly controversial. Recommendations from in vitro and animal research often lead to different clinical outcomes because it is difficult to translate non-clinical study outcomes and methodology recommendations to human clinical treatment protocols. In recent years, significant progress has been made in understanding the mechanism of PRP action. In this review, we will discuss mechanisms related to inflammation and chondrogenesis in cartilage repair and regenerative processes after PRP administration in in vitro and animal studies. Furthermore, we review clinical trials of PRP efficiency in changing the OA biomarkers in knee joint.

A Retrospective Analysis of Characteristic Features of Responders and Impaired Patients to a Single Injection of Pure Platelet-Rich Plasma in Knee Osteoarthritis

(1) Background: The emergence of injectable “biologic” medication creates a new approach to treat osteoarthritis (OA). Among them, the use of intra-articular injection of PRP became widespread despite the absence of consensus regarding its optimal composition. The aim of this study was to retrospectively correlate an extensive biological characterization of injected PRP to the clinical responses of patients presenting knee OA. (2) Methods: This retrospective study included 75 patients with knee OA. Cartilage lesions were assessed using magnetic resonance imaging and the International Cartilage Regeneration Society (ICRS) classification. PRP extensive biological characterization was performed and patients’ subjective symptoms were recorded before injection and 3 and 6 months after injection using the Knee injury and Osteoarthritis Outcome Score (KOOS). Responders were defined by an improvement of 10 points on KOOS. (3) Results: At 6 months, 63.0% of the patients were responders. Impairment was characterized by a significantly higher proportion of patients with three compartments altered at baseline MRI and receiving a significantly higher dose of platelets compared to responders. (4) Conclusions: Single injection of pure PRP resulted in significant clinical improvement in the management of knee OA. Both baseline MRI and PRP biological features may be predictive factors of the clinical response, highlighting that a better understanding of action mechanism of PRP is still required.

Moving toward targeting the right phenotype with the right platelet-rich plasma (PRP) formulation for knee osteoarthritis

Intra-articular injections of platelet-rich plasma (PRP) and other novel blood-derived products developed specifically for osteoarthritis (OA) can provide pain relief and potential benefits in disease progression. Meta-analyses show the clinical superiority of PRP compared with other intra-articular injections, but results are modest and the effect sizes are small. PRP injections in knee OA are performed indiscriminately, but the clinical response varies enormously between patients because of an array of mixed OA phenotypes. Subgroup analyses are scarce; some studies stratify patients according to radiographic severity and found better results in early OA, without consensus for more advanced stages of the condition. Parallel identification of soluble and imaging biomarkers is essential to personalise and leverage PRP therapies. The inflammatory phenotype is most interesting from the PRP perspective because PRPs modulate inflammation by releasing a large pool of chemokines and cytokines, which interact with synovial fibroblasts and macrophages; in addition, they can modulate the innate immune response. No soluble biomarkers have been discovered that have implications for OA research and PRP interventions. Clinical examination of patients based on their inflammatory phenotype and imaging identification of pain sources and structural alterations could help discern who will respond to PRP. Synovial inflammation and bone marrow lesions are sources of pain, and intra-articular injections of PRP combined with subchondral bone injection can enhance clinical outcomes. Further refining ultrasound phenotypes may aid in personalising PRP therapies. Intra-articular delivery combined with injections in altered ligamentous structures, medial and coronal ligaments or premeniscal pes anserinus showed positive clinical outcomes. Although the evidence supporting these approaches are weak, they merit further consideration to refine PRP protocols and target the right OA phenotypes.

From Pathogenesis to Therapy in Knee Osteoarthritis: Bench-to-Bedside

Osteoarthritis (OA) is currently the most widespread musculoskeletal condition and primarily affects weight-bearing joints such as the knees and hips. Importantly, knee OA remains a multifactorial whole-joint disease, the appearance and progression of which involves the alteration of articular cartilage as well as the synovium, subchondral bone, ligaments, and muscles through intricate pathomechanisms. Whereas it was initially depicted as a predominantly aging-related and mechanically driven condition given its clear association with old age, high body mass index (BMI), and joint malalignment, more recent research identified and described a plethora of further factors contributing to knee OA pathogenesis. However, the pathogenic intricacies between the molecular pathways involved in OA prompted the study of certain drugs for more than one therapeutic target (amelioration of cartilage and bone changes, and synovial inflammation). Most clinical studies regarding knee OA focus mainly on improvement in pain and joint function and thus do not provide sufficient evidence on the possible disease-modifying properties of the tested drugs. Currently, there is an unmet need for further research regarding OA pathogenesis as well as the introduction and exhaustive testing of potential disease-modifying pharmacotherapies in order to structure an effective treatment plan for these patients.

Effects and mechanism of platelet-rich plasma on military drill injury: a review

Military drill injury is a significant part of military medical research. The increase of training intensity and changes in training methods lead to differences in injury types. The ideal therapeutic modality should allow rapid healing at a reasonable cost and minimize impact on patients' life. Platelet -rich plasma (PRP), a platelet concentrate, is rich in a variety of growth factors and widely used clinically as a minimally invasive treatment. It plays an important role in injury repair and rehabilitation. In this article, we review the therapeutic role of PRP in military drill injury and its possible underlying mechanisms, with a focus on plantar fasciitis, stress fractures and other common injuries, in order to provide basic support for military reserve.

Multimodal approach to intraarticular drug delivery in knee osteoarthritis

The expectations from any future disease-modifying treatment for knee osteoarthritis (KOA) are extremely high as it has to impact the joint as a whole leading to favorable alterations of diverse tissues and functions. In this light, targeting the knee only from the inside may not be biologically justified for the management of a whole joint disease such as KOA. Our hypothesis to test is whether any injectable therapeutic intervention alone can lead to disease modification of KOA which is viewed in the complexity of the modern concept of osteoarthritis (OA) as a whole joint disease. Therefore, we aimed at analyzing the intraarticular route to the KOA patient in an attempt to unveil its "biological" constraints. A comprehensive search through databases was carried out using specific keywords to add objectivity to the main messages. The literature analysis has shown that "cutting-edge" intraarticular therapies may offer a key to non-invasive symptomatic relief. Changing the course of KOA, however, may necessitate a multimodal approach towards the knee joint including a combination of intraarticular injections with interventions on multiple levels. Importantly, our understanding of OA has evolved redefining the concept of the disease, being in interaction with the human body as a whole. Any future conservative disease-modifying treatment of KOA should aim at a multimodal, holistic approach towards the knee joint including but not limited only to intraarticular injections. A combination with other interventions should be further researched.

Micro-Clotting of Platelet-Rich Plasma Upon Loading in Hydrogel Microspheres Leads to Prolonged Protein Release and Slower Microsphere Degradation

Platelet-rich plasma (PRP) is an autologous blood product that contains a variety of growth factors (GFs) that are released upon platelet activation. Despite some therapeutic potential of PRP in vitro, in vivo data are not convincing. Bolus injection of PRP is cleared rapidly from the body diminishing its therapeutic efficacy. This highlights a need for a delivery vehicle for a sustained release of PRP to improve its therapeutic effect. In this study, we used microfluidics to fabricate biodegradable PRP-loaded polyethylene glycol (PEG) microspheres. PRP was incorporated into the microspheres as a lyophilized PRP powder either as is (powder PRP) or first solubilized and pre-clotted to remove clots (liquid PRP). A high PRP loading of 10% w/v was achieved for both PRP preparations. We characterized the properties of the resulting PRP-loaded PEG microspheres including swelling, modulus, degradation, and protein release as a function of PRP loading and preparation. Overall, loading powder PRP into the PEG microspheres significantly affected the properties of microspheres, with the most pronounced effect noted in degradation. We further determined that microsphere degradation in the presence of powder PRP was affected by platelet aggregation and clotting. Platelet aggregation did not prevent but prolonged sustained PRP release from the microspheres. The delivery system developed and characterized herein could be useful for the loading and releasing of PRP to promote tissue regeneration and wound healing or to suppress tissue degeneration in osteoarthritis, and intervertebral disc degeneration.

Evidence on ankle injections for osteochondral lesions and osteoarthritis: a systematic review and meta-analysis

PURPOSE

To evaluate the evidence supporting safety and effectiveness of intra-articular injective treatments for ankle lesions ranging from osteochondral lesions of the talus (OLT) to osteoarthritis (OA).

METHODS

A systematic review and a meta-analysis were performed on PubMed, Embase, and Cochrane Library in March 2020. Safety was evaluated through the reported side effects and effectiveness through the scores used. The quality of the studies was assessed using the Cochrane Collaboration Risk of Bias 2.0 tool and the Downs and Black checklist. For each outcome, the quality of evidence was graded according to GRADE guidelines.

RESULTS

Twenty-four studies (21 for OA, 3 for OLT) were included on hyaluronic acid (HA), platelet-rich plasma (PRP), saline, methylprednisolone, botulinum toxin type A (BoNT-A), mesenchymal stem cells (MSCs), and prolotherapy. No severe adverse events were reported. For OLT, a comparison was possible between HA and PRP showing no significant difference. For ankle OA, a significant difference favouring HA versus saline was documented at six months (p < 0.001). The GRADE level of evidence was very low.

CONCLUSION

This meta-analysis supports the safety of intra-articular treatment for ankle OA and OLT, while only a very low evidence supports the efficacy of HA in terms of better results versus placebo for the treatment of ankle OA, and other conclusions are hindered by the scarcity of the available literature. This urges further and stronger trials to specifically investigate potential and limitations of these different injective approaches for the treatment of OLT and ankle OA.

The Clinical Use of Platelet-Rich Plasma in Knee Disorders and Surgery-A Systematic Review and Meta-Analysis

In recent years, the interest in biological treatment of knee lesions has increased, especially the application of platelet-rich plasma is of particular note. The number of articles evaluating platelet-rich plasma (PRP) efficacy in the recovery of knee disorders and during knee surgery has exponentially increased over the last decade. A systematic review with meta-analyses was performed by assessing selected studies of local PRP injections to the knee joint. The study was completed in accordance with 2009 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A multistep search of PubMed, Embase, Cochrane Database of Systematic Reviews, and Clinicaltrials.gov was performed to identify studies on knee surgery and knee lesion treatment with PRP. Of the 4004 articles initially identified, 357 articles focusing on knee lesions were selected and, consequently, only 83 clinical trials were analyzed using the revised Cochrane risk-of-bias tool to evaluate risk. In total, seven areas of meta-analysis reported a positive effect of PRP. Among them, 10 sub-analyses demonstrated significant differences in favor of PRP when compared to the control groups (p < 0.05). This study showed the positive effects of PRP, both on the recovery of knee disorders and during knee surgery; however further prospective and randomized studies with a higher number of subjects and with lower biases are needed.

The molecular mechanism of platelet lysate promotes transformation of non-union cells into osteoblasts

Background

Platelet lysate (PL) had a remarkable therapeutic effect on bone repair related diseases, such as delayed fracture healing, femoral head necrosis and meniscal tear. In this study, we investigated the effect of PL on patients with nonunion, cartilage repair and osteonecrosis, and to evaluate the effect of PL on nonunion cells proliferation and the effect of PL on OPG/RANKL signaling pathway in nonunion cell of male rats. To reveal the molecular mechanism of PL for bone healing.

Methods

We used different concentrations of PL to treat nonunion cells, then detected cell proliferation and protein expression levels of osteoprotegerin (OPG), RANKL, osteopontin (OPN), osteocalcin (OCN) and alkaline phosphatase (ALP).

Results

The proliferation rate of nonunion cells treated by 5% PL, was significantly higher than that of the control group (P<0.05). Surprisingly, there were no significant difference among the proliferation rates of nonunion cells treated by 8% PL, 10% FBS and the control group (P>0.05). the results of western blot analysis and immunofluorescence analysis showed that PL improved the expression of OPG, OPN, OCN and ALP proteins in nonunion cells, but PL had no effect on the expression of nuclear factor-κB ligand (RANKL) protein.

Conclusions

We found that PL had a remarkable therapeutic effect on bone repair related diseases; 5% PL significantly improved the proliferation rate of the nonunion cells; 10% PL had a significantly positive effect on improving the expression levels of osteogenic related genes.

Platelet Concentrates in Musculoskeletal Medicine

Platelet concentrates (PCs), mostly represented by platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) are autologous biological blood-derived products that may combine plasma/platelet-derived bioactive components, together with fibrin-forming protein able to create a natural three-dimensional scaffold. These types of products are safely used in clinical applications due to the autologous-derived source and the minimally invasive application procedure. In this narrative review, we focus on three main topics concerning the use of platelet concentrate for treating musculoskeletal conditions: (a) the different procedures to prepare PCs, (b) the composition of PCs that is related to the type of methodological procedure adopted and (c) the clinical application in musculoskeletal medicine, efficacy and main limits of the different studies.

An Analysis of Current Treatment Trends in Platelet-Rich Plasma Therapy in the Medicare Database

Background:

The use of platelet-rich plasma (PRP) in the Medicare population is not well described.

Purpose:

To investigate the national use of PRP among Medicare beneficiaries, including the incidence and conditions for which it was used in both operative and nonoperative settings, and determine charges to Medicare.

Study Design:

Descriptive epidemiology study.

Methods:

The Medicare Standard Analytical Files within the PearlDiver database were queried for PRP injections by use of Current Procedural Terminology (CPT) code 0232T from 2010 to 2014. A search of every associated International Classification of Diseases, 9th Revision, code and CPT code on the day of the injection was performed, and codes were broadly categorized as shoulder, knee, elbow, hip, and foot/ankle. These categories were then subdivided into 2 groups based on whether the injection was performed at the time of surgery or for a nonoperative condition. The patient data were analyzed by demographics and geographic region. In further analysis, the charges sent to Medicare for PRP injections were stratified by year and musculoskeletal site.

Results:

A total of 3654 PRP injections were coded for and administered during the study period; 57% of recipients were men and 33% were 65 to 69 years of age. We found that 42% of all PRP injections were administered in the southern geographic region. PRP injections were most commonly associated with shoulder diagnoses, followed closely by the foot and ankle and by the knee. The majority of injections given for shoulder conditions were performed at the time of surgery, whereas the majority of knee conditions treated with PRP were associated with nonoperative treatments. Annual charges to Medicare for PRP injections increased 400%, from $500,000 in 2010 to more than $2 million in 2014.

Conclusion:

The use and breadth of PRP therapy have increased substantially in Medicare beneficiaries. Further research is required to obtain a consensus on treatment recommendations for PRP use in this population in addition to strategies to obtain insurance reimbursement.

Autologous platelet-rich plasma therapy for refractory pain after low-grade medial collateral ligament injury

Objective

This study was performed to explore the effect of intra-articular injection of autologous platelet-rich plasma (PRP) on refractory pain after low-grade medial collateral ligament (MCL) injury.

Methods

In total, 52 patients with refractory pain after low-grade knee MCL injury were treated by intra-articular injection of autologous PRP. Every patient received a 5-mL intra-articular injection of autologous PRP once weekly for 3 weeks. All patients were evaluated by the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form score before treatment and 1, 3, and 6 months after treatment. Magnetic resonance imaging of the knee was performed to observe the healing of the MCL injury 6 months after treatment.

Results

After one injection, the patients’ pain was greatly decreased and they stopped taking nonsteroidal anti-inflammatory drugs. The IKDC Subjective Knee Evaluation Form scores were significantly better after than before treatment; however, there were no significant differences among the various post-treatment time points. Magnetic resonance imaging showed that the low-grade MCL injury had completely healed, and no edema was present around the MCL.

Conclusions

Intra-articular injection of autologous PRP is an effective treatment for refractory pain after low-grade MCL injury.

Inflammatory cytokines via up-regulation of aquaporins deteriorated the pathogenesis of early osteoarthritis

BACKGROUND

Inflammatory cytokines enhanced the progress of the pathogenesis of osteoarthritis, however the mechanisms remain unclear. The objective is to determine aquaporins (AQPs) in the pathogenesis of osteoarthritis.

METHODS AND FINDINGS

Primary rat articular chondrocytes were treated with IL-1β to mimic the early stage of osteoarthritis in vitro. Early osteoarthritis animal model was established by intra-articular injection of 4% papain. Micro- or ultra-structure histopathologic changes, cell viability, apoptosis cells and cell membrane permeability, locations and expressions of AQP1 and AQP3 and matrix were detected in the cartilage or in the chondrocytes of knee. IL-1β could reduce the chondrocytes viability, increase the apoptosis cells, and also impair the cell membrane and organelles. IL-1β significantly induced the up-regulation of AQP1 and AQP3 in the chondrocytes. In the chondrocytes, AQPs were mainly clustered in both membrane and perinuclear region of cytoplasm, while higher AQPs were detected in the superficial and middle layers of the cartilage. With the up-regulation of AQPs, the cartilage matrix was considerably decreased in both the chondrocytes and in the osteoarthritis cartilage. In the early osteoarthritis rat model, serum and synovial fluid confirmed that higher IL-1β could increase the expressions of AQPs, and decrease the cartilage matrix in both the chondrocytes and the cartilage.

CONCLUSIONS

Inflammatory cytokine IL-1β via up-regulation of AQPs caused the abnormal metabolism of water transport and loss of the cartilage matrix in the chondrocytes, and ultimately exacerbated the pathogenesis of early osteoarthritis. Therefore, AQPs may be a candidate therapeutic target for prevention and treatment of osteoarthritis.

The Clinical Use of Biologics in the Knee Lesions: Does the Patient Benefit?

PURPOSE OF REVIEW

Overview the outcomes of the latest use of platelet-rich plasma (PRP) for the treatment of knee lesions in the clinics and discuss the challenges and limitations.

RECENT FINDINGS

Recent clinical studies mainly indicate there may be benefit of PRP usage for the treatment of knee lesions. As an autologous source of bioactive components, PRP has been shown to be typically safe, free of major adverse outcomes. The use of PRP has been continuously increasing, and some well-designed, double-blinded, placebo-controlled clinical trials have been published. Clinical outcomes relating to PRP usage are multifactorial and depend on the severity of the lesion and patient characteristics. Although PRP is safe to use and it can be easily applied in the clinics, case-specific considerations are needed to determine whether PRP could be beneficial or not. If the use of PRP is favored, then, the configuration/optimization of the preparation and administration/delivery strategy with or without a concomitant treatment may further enhance the clinical outcomes and patients' experience.

Blood Plasma Derivatives for Tissue Engineering and Regenerative Medicine Therapies

Platelet-rich plasma (PRP) and its derivatives have been investigated and applied in regenerative medicine. The use of PRP as a supplement of cell culture media has consistently shown to potentiate stem cell proliferation, migration, and differentiation. In addition, the clinical utility of PRP is supported by evidence that PRP contains high concentrations of growth factors (GFs) and proteins which contribute to the regenerative process. PRP based therapies are cost effective and also benefit from the accessibility and safety of using the patient's own GFs. In the last years, a great development has been witnessed on PRP based biomaterials, with both structural and functional purposes. In this study we overview the most relevant PRP applications encompassing PRP based materials for tissue engineering and regenerative medicine. This review also summarizes the challenges in the fields of tissue engineering and regenerative medicine and provides a perspective on future directions.

Biological and Mechanical Properties of Platelet-Rich Fibrin Membranes after Thermal Manipulation and Preparation in a Single-Syringe Closed System

Platelet-rich fibrin (PRF) membrane is a three-dimensional biodegradable biopolymer, which consists of platelet derived growth factors enhancing cell adhesion and proliferation. It is widely used in soft and hard tissue regeneration, however, there are unresolved problems with its clinical application. Its preparation needs open handling of the membranes, it degrades easily, and it has a low tensile strength which does not hold a suture blocking wider clinical applications of PRF. Our aim was to produce a sterile, suturable, reproducible PRF membrane suitable for surgical intervention. We compared the biological and mechanical properties of PRF membranes created by the classical glass-tube and those that were created in a single-syringe closed system (hypACT Inject), which allowed aseptic preparation. HypACT Inject device produces a PRF membrane with better handling characteristics without compromising biological properties. Freeze-thawing resulted in significantly higher tensile strength and higher cell adhesion at a lower degradation rate of the membranes. Mesenchymal stem cells seeded onto PRF membranes readily proliferated on the surface of fresh, but even better on freeze/thawed or freeze-dried membranes. These data show that PRF membranes can be made sterile, more uniform and significantly stronger which makes it possible to use them as suturable surgical membranes.

Repair of Damaged Articular Cartilage: Current Approaches and Future Directions

Articular hyaline cartilage is extensively hydrated, but it is neither innervated nor vascularized, and its low cell density allows only extremely limited self-renewal. Most clinical and research efforts currently focus on the restoration of cartilage damaged in connection with osteoarthritis or trauma. Here, we discuss current clinical approaches for repairing cartilage, as well as research approaches which are currently developing, and those under translation into clinical practice. We also describe potential future directions in this area, including tissue engineering based on scaffolding and/or stem cells as well as a combination of gene and cell therapy. Particular focus is placed on cell-based approaches and the potential of recently characterized chondro-progenitors; progress with induced pluripotent stem cells is also discussed. In this context, we also consider the ability of different types of stem cell to restore hyaline cartilage and the importance of mimicking the environment in vivo during cell expansion and differentiation into mature chondrocytes.