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

Cytotoxicity of local anaesthetics and protective effects of platelet rich plasma on equine tenocytes: An in vitro study

Local anaesthetics (LAs) can have detrimental effects on rat, bovine, canine, and human tendon tissues and cells. Currently, there has been no available data on the impact of these drugs on equine tenocytes. Even if LA injection for managing painful tendon conditions in horses is limited, it is usually used via intra-articular, intrasynovial, perineural, and intrathecal as well as for lameness examinations. In this in vitro study, the cytotoxic effects of LAs, including lidocaine, mepivacaine, and bupivacaine on equine tenocytes, in the presence and absence of platelet rich plasma (PRP), were investigated. PRP accelerates tissue healing and can exert cytoprotective effects on different cell types exposed to different stressful conditions, including drugs. Results indicated that the exposure to LAs significantly reduced tenocytes viability in dose- and time-dependent manners while PRP was able to counteract their cytotoxic effects. Furthermore, microscopy and flow cytometry analyses revealed apoptosis and necrosis in equine tenocytes exposed to these drugs, that were both reduced when PRP was in the medium. These findings highlight the importance of considering the tenocyte toxicity associated with intrathecal and intraneural LA injections, as they might affect tenocytes or reduce the efficacy of associated therapies. Moreover, this study also highlights the protective effects of PRP, which could make LA injections safer.

A comparative study of platelet storage lesion in platelet-rich plasma under cryopreservation

Platelet-rich plasma (PRP) has significant potential for various applications and holds clinical value in regenerative medicine. Cryopreservation is used to extend the preservation period of PRP, facilitating its clinical application. However, the potential negative effects of long-term cryopreservation on platelet storage lesion are still uncertain. In this study, PRP was stored at - 30 °C or - 80 °C. Platelet count, apoptosis, reactive oxygen species (ROS) content, and CD62P expression were assessed on the 14th and 28th days. The study also evaluated platelet mitochondria morphology and function, serotonin (5-HT) secretion by platelets, and the inflammatory activating effect of cryopreserved platelets in PRP. The results showed that there were no significant differences in platelet count, the content of 5-HT, and inflammatory effects between fresh PRP and PRP cryopreserved at both - 30 °C and - 80 °C. However, there was an increase in ROS level, apoptosis, and CD62P level after cryopreservation at both temperatures. Additionally, the levels of ROS, apoptosis, and CD62P in platelets were similar after storage at - 30 °C and - 80 °C. The main difference observed was that the morphology and function of mitochondria were severely damaged after storage at - 30 °C, while they were less affected at - 80 °C. Based on these findings, it can be concluded that storing PRP at - 80 °C is more suitable for achieving a better therapeutic effect in clinical applications, but cryopreservation could not replace the current standard.

Efficacy of platelet-rich plasma and platelet-rich fibrin in arthroscopic rotator cuff repair: A systematic review and meta-analysis

OBJECTIVE

Basic scientific studies have demonstrated positive effects of platelet-rich therapies, such as platelet-rich plasma (PRP) and platelet-rich fibrin (PRF), on tendon repair. However, clinical evidence indicating improved prognosis is controversial. In this study, we aimed to determine whether augmentation of arthroscopic rotator cuff repair with PRP and PRF improves outcomes compared to arthroscopic repair alone.

LITERATURE SURVEY

PubMed, Embase, and Cochrane library databases were comprehensively searched for randomized controlled trials (RCTs) published until June 2022 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. No language restriction was applied.

METHODOLOGY

The primary outcomes were the rate of repeat tears after arthroscopic rotator cuff repair (retear rate) and clinical function scores (Constant-Murley Score, University of California, Los Angeles Score), and the extracted data were assessed for quality. Statistical analyses were performed using Review manager 5.3, and p < .05 was considered statistically significant.

SYNTHESIS

Ten RCTs with 628 patients were included. The results showed that augmenting surgery with PRP reduces retear rates compared to surgery alone (risk ratio [RR] = 0.40, 95% confidence interval [CI] 0.23-0.69, p = .001), whereas PRF has no effect on retear rates (p = .92). Regarding clinical function, PRP improves Constant-Murley scores (mean difference [MD] = 2.03, 95% CI 0.13-3.93, p = .04) and University of California, Los Angeles scores (MD = 1.30, 95% CI 0.36-2.24, p = .007), whereas PRF improves only Constant-Murley scores (MD = 3.93, 95% CI 1.50-6.36, p = .002). However, these differences were small and below the minimum clinically important difference threshold.

CONCLUSIONS

This study showed that compared to arthroscopic rotator cuff repair alone, the application of PRP in arthroscopic rotator cuff repair reduces retear rate and improves clinical function scores, whereas the application of PRF has no clinically meaningful benefit. The small number and heterogeneity of studies as well as methodological limitations and risk of bias limit confidence in the true effect.

[Platelet-rich plasma (PRP) : Compositional analysis with different dietary habits and timing of blood sampling]

The variability of PRP is a major contributor to the lack of evidence regarding the therapeutic effect of PRP in musculoskeletal diseases. In a large study, we are currently investigating factors that may influence PRP variability. Interim results showed that concentrations of IL‑6, but not IGF‑1 or cellular constituents, were significantly decreased in PRP samples from vegans compared with omnivores and tended to be decreased compared to samples from vegetarians. This suggests that diet may have a significant influence on therapeutically active PRP constituents. However, the constituents studied here did not appear to be significantly affected by the timing of the sampling. Identification of significant variables affecting PRP composition will be critical to provide sufficient medical evidence for the therapeutic effects of PRP in orthopedic conditions.

Platelet-derived biomaterial with hyaluronic acid alleviates temporal-mandibular joint osteoarthritis: clinical trial from dish to human

BACKGROUND

Bioactive materials have now raised considerable attention for the treatment of osteoarthritis (OA), such as knee OA, rheumatoid OA, and temporomandibular joint (TMJ) OA. TMJ-OA is a common disease associated with an imbalance of cartilage regeneration, tissue inflammation, and disability in mouth movement. Recently, biological materials or molecules have been developed for TMJ-OA therapy; however, ideal treatment is still lacking. In this study, we used the combination of a human platelet rich plasma with hyaluronic acid (hPRP/HA) for TMJ-OA therapy to perform a clinical trial in dish to humans.

METHOD

Herein, hPRP was prepared, and the hPRP/HA combined concentration was optimized by MTT assay. For the clinical trial in dish, pro-inflammatory-induced in-vitro and in-vivo mimic 3D TMJ-OA models were created, and proliferation, gene expression, alcian blue staining, and IHC were used to evaluate chondrocyte regeneration. For the animal studies, complete Freund's adjuvant (CFA) was used to induce the TMJ-OA rat model, and condyle and disc regeneration were investigated through MRI. For the clinical trial in humans, 12 patients with TMJ-OA who had disc displacement and pain were enrolled. The disc displacement and pain at baseline and six months were measured by MRI, and clinical assessment, respectively.

RESULTS

Combined hPRP/HA treatment ameliorated the proinflammatory-induced TMJ-OA model and promoted chondrocyte proliferation by activating SOX9, collagen type I/II, and aggrecan. TMJ-OA pathology-related inflammatory factors were efficiently downregulated with hPRP/HA treatment. Moreover, condylar cartilage was regenerated by hPRP/HA treatment in a proinflammatory-induced 3D neocartilage TMJ-OA-like model. During the animal studies, hPRP/HA treatment strongly repaired the condyle and disc in a CFA-induced TMJ-OA rat model. Furthermore, we performed a clinical trial in humans, and the MRI data demonstrated that after 6 months of treatment, hPRP/HA regenerated the condylar cartilage, reduced disc displacement, alleviated pain, and increased the maximum mouth opening (MMO). Overall, clinical trials in dish to human results revealed that hPRP/HA promoted cartilage regeneration, inhibited inflammation, reduced pain, and increased joint function in TMJ-OA.

CONCLUSION

Conclusively, this study highlighted the therapeutic potential of the hPRP and HA combination for TMJ-OA therapy, with detailed evidence from bench to bedside. Trial registration Taipei Medical University Hospital (TMU-JIRB No. N201711041). Registered 24 November 2017. https://tmujcrc.tmu.edu.tw/inquiry_general.php .

Infiltration therapy in the context of cartilage surgery

Guideline-based surgical cartilage therapy for focal cartilage damage offers highly effective possibilities to sustainably reduce patients' complaints and to prevent or at least delay the development of early osteoarthritis. In the knee joint, it has the potential to reduce almost a quarter of the arthroses requiring joint replacement caused by cartilage damage. Biologically effective injection therapies could further improve these results. Based on the currently available literature and preclinical studies, intra- and postoperative injectables may have a positive effect of platelet-rich plasma/fibrin (PRP/PRF) and hyaluronic acid (HA) on cartilage regeneration and, in the case of HA injections, also on the clinical outcome can be assumed. The role of a combination therapy with use of intra-articular corticosteroids is lacking in the absence of adequate study data and cannot be defined yet. With regard to adipose tissue-based cell therapy, the current scientific data do not yet justify any recommendation for its use. Further studies also regarding application intervals, timing and differences in different joints are required.

Aging Affects the Efficacy of Platelet-Rich Plasma Treatment for Osteoarthritis

OBJECTIVE

Despite the increased use of platelet-rich plasma in the treatment of osteoarthritis, whether and how age of the platelet-rich plasma donor affects therapeutic efficacy is unclear.

DESIGN

In vitro, male osteoarthritic human chondrocytes were treated with platelet-rich plasma from young (18-35 yrs) or old (≥65 yrs) donors, and the chondrogenic profile was evaluated using immunofluorescent staining for two markers of chondrogenicity, type II collagen and SOX-9. In vivo, we used a within-subjects design to compare Osteoarthritis Research Society International scores in aged mouse knee joints injected with platelet-rich plasma from young or old individuals.

RESULTS

In vitro experiments revealed that platelet-rich plasma from young donors induced a more youthful chondrocyte phenotype, as evidenced by increased type II collagen ( P = 0.033) and SOX-9 expression ( P = 0.022). This benefit, however, was significantly blunted when cells were cultured with platelet-rich plasma from aged donors. Accordingly, in vivo studies revealed that animals treated with platelet-rich plasma from young donors displayed a significantly improved cartilage integrity when compared with knees injected with platelet-rich plasma from aged donors ( P = 0.019).

CONCLUSIONS

Injection of platelet-rich plasma from a young individual induced a regenerative effect in aged cells and mice, whereas platelet-rich plasma from aged individuals showed no improvement in chondrocyte health or cartilage integrity.

Efficacy and safety of platelet-rich plasma injections for the treatment of osteoarthritis: a systematic review and meta-analysis of randomized controlled trials

Background

In recent years, platelet-rich plasma (PRP) injections for osteoarthritis (OA) have been widely promoted in clinical practice, but their effectiveness is controversial. Therefore, we conducted a meta-analysis of relevant randomized controlled trials (RCTs) to determine the efficacy and safety of PRP injections for the treatment of OA.

Methods

We searched databases including Embase, Web of Science, Medline, PubMed, and the Cochrane Library for relevant studies. Two researchers (YQX and CG) performed literature screening, baseline data extraction, literature quality assessment, and heterogeneity analysis of RCTs from the retrieved studies. Based on the magnitude of heterogeneity I², random-effects or fixed-effects models were selected for the meta-analysis.

Results

We included 24 RCTs comprising 1344 patients with OA who met the inclusion criteria, with the main types of morbidity being knee osteoarthritis (KOA), hip osteoarthritis (HOA), ankle osteoarthritis (AOA), and temporomandibular joint osteoarthritis (TMJOA). Our results indicate that PRP injections were effective in improving Visual Analog Scale (VAS) pain scores in patients with KOA, HOA, and AOA compared to controls (AOA, MD = -1.15, CI = 95% [-1.74, -0.56], I² = 40%, P < 0.05; KOA, MD = -1.03, CI = 95% [-1.16, -0.9], I² = 87%, P < 0.05; TMJOA, MD = -1.35, CI = 95% [-1.74, -0.97], I² = 92%, P < 0.05) but showed no significant efficacy in patients with HOA (MD = -0.27, CI = 95% [-0.8, 0.26], I² = 56%, P>0.05). Compared to controls, PRP injections were effective in improving Knee Injury and Osteoarthritis Outcome Score (KOOS), including the patient's pain symptoms, activities of daily living (ADL), and adhesion symptomatology, but not for that of sports function (KOOS-pain, MD = 2.77, CI = 95% [0, 5.53], I² = 0%, P < 0.05; KOOS-symptoms, MD = 3.73, CI = 95% [0.76, 6.71], I² = 0%, P < 0.05; KOOS-ADL, MD = 3.61, CI = 95% [0.79, 6.43], I² = 0%, P < 0.05; KOOS-QOL, MD = 4.66, CI = 95% [0.98, 8.35], I² = 29%, P < 0.05, KOOS-sport, MD = 0.48, CI = 95% [-3.02, 3.98], I² = 0%, P > 0.05). PRP injections were effective in improving Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores, including pain, stiffness, and functional joint motion, in patients with OA compared with the control group (WOMAC-pain, MD = -1.08, CI = 95% [-1.62, -0.53], I² = 87%, P < 0.05; WOMAC-stiffness, MD = -1.17, CI = 88% [-1.72, -0.63], I² = 87%, P < 0.05; WOMAC-function, MD = -1.12, CI = 95% [-1.65, -0.58], I² = 87%, P < 0.05). In addition, subgroup analysis showed that leukocyte-poor (LP) PRP injections were more effective than leukocyte-rich (LR) PRP injections in improving pain symptoms in patients with OA (VAS, LR-PRP, MD = -0.81, CI = 95% [-1.65, -0.03], I² = 83%, P = 0.06 > 0.05; LP-PRP, MD = -1.62, CI = 95% [-2.36, -0.88], I² = 92%, P < 0.05). A subgroup analysis based on injection sites showed that no statistical difference in efficacy between intra-articular (IA) combined with intra-osseous (IO) simultaneous PRP injections. IA PRP injections only improved VAS pain scores in patients with OA (IA+IO PRP injections, MD = -0.74, CI =95% [-1.29, -0.18], I² = 61%, P < 0.05; IA PRP injections, MD = -1.43, CI = 95% [-2.18, -0.68], I² = 87%, P < 0.05, test for subgroup differences, P > 0.05, I² = 52.7%).

Conclusion

PRP injection therapy can safely and effectively improve functional activity in patients with OA and produce positive analgesic effects in patients with KOA, TMJOA, and AOA. However, PRP injection therapy did not significantly reduce pain symptoms in patients with HOA. In addition, the analgesic effect of LP-PRP was greater than that of LR-PRP.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022362066.

Orthobiologics: a review

PURPOSE

The use of biologic materials in orthopaedics (orthobiologics) has gained significant attention over the past years. To enhance the body of the related literature, this review article is aimed at summarizing these novel biologic therapies in orthopaedics and at discussing their multiple clinical implementations and outcomes.

METHODS

This review of the literature presents the methods, clinical applications, impact, cost-effectiveness, and outcomes, as well as the current indications and future perspectives of orthobiologics, namely, platelet-rich plasma, mesenchymal stem cells, bone marrow aspirate concentrate, growth factors, and tissue engineering.

RESULTS

Currently available studies have used variable methods of research including biologic materials as well as patient populations and outcome measurements, therefore making comparison of studies difficult. Key features for the study and use of orthobiologics include minimal invasiveness, great healing potential, and reasonable cost as a nonoperative treatment option. Their clinical applications have been described for common orthopaedic pathologies such as osteoarthritis, articular cartilage defects, bone defects and fracture nonunions, ligament injuries, and tendinopathies.

CONCLUSIONS

Orthobiologics-based therapies have shown noticeable clinical results at the short- and mid-term. It is crucial that these therapies remain effective and stable in the long term. The optimal design for a successful scaffold remains to be further determined.

Orthobiologics and hyaluronic acid usage in the Netherlands: an electronic survey of 265 orthopaedic surgeons and sports physicians

Purpose

“Biologic therapies” in the field of orthopaedic surgery and sports medicine, so called orthobiologics, have been gaining significant interest from physicians and patients, with increasing usage over the recent years. The aim of this study is to (1) evaluate the usage of orthobiologics in the Netherlands, (2) to clarify the reasons for the use or non-use of orthobiologics, and (3) the most addressed disease for use of orthobiologics.

Methods

The authors created a 19-quenstion online survey comprised of both closed-ended and open-ended response questions in order to examine the use of and the indication for orthobiologics. The survey was sent to all the members of the Dutch Orthopaedic Association and Netherlands Association of Sports Medicine of which 15% responded.

Results

The majority of the 265 respondents (65%) did not treat patients with or refer patients for treatment with orthobiologics. The most important reasons for not using orthobiologics were the lack of scientific evidence, the lack of good experience, and the lack of insurance coverage. Of the physicians that used orthobiologics, the most used hyaluronic acid (76%) and platelet-rich plasma (27%). Orthobiologics were most used for knee osteoarthritis and medial or lateral epicondylitis.

Conclusion

Although some orthobiologic treatments might be effective and the research interest is growing, our study shows that the majority of orthopaedic and sport physician clinicians in the Netherlands still does not make use of orthobiologics as a treatment option, but almost a third of them is contemplating to start using orthobiologics.

Level of evidence

III.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-021-00380-9.

Platelet-rich plasma for tendinopathy and osteoarthritis: a narrative review

Background

Musculoskeletal disorders include a wide range of degenerative and inflammatory problems, which can affect any part of the muscular and skeletal system. Platelet-rich plasma (PRP) has been a breakthrough in musculoskeletal medicine, especially with its effects to speed up soft tissue, cartilage, and bone healing. It is now thought that stem cells are able to reverse the degenerative process and promote rapid healing. Platelet-rich plasma (PRP) has received special attention in treating tendinopathy and osteoarthritis. This review aims to do a comprehensive review of the scientific evidence for the efficiency of PRP application in tendinopathy and osteoarthritis.

Main body of the abstract

In osteoarthritis treatment, platelet-rich plasma is thought to influence the whole joint environment by increasing chondrocyte proliferation. The injection of autologous PRP into the joint space and surrounding soft tissues delivers a concentrated dose of these growth factors, which accelerate the healing process and reduce pain.

Short conclusion

Many studies report some benefits in regard to pain and functionality, especially in tendinopathy, but further investigations are needed to incorporate PRP into clinical practice and be a common form of therapy for tendinopathy and osteoarthritis. Caution should be applied with any treatment we use in clinical practice, especially with PRP and other forms of injections.

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.