Red Blood Cells in Platelet-Rich Plasma: Avoid If at All Possible

Minimum reporting requirements for platelet-rich plasma in biomaterial research

Platelet-rich plasma (PRP) is gaining significant attention in regenerative medicine, offering an abundance of growth factors and bioactive molecules that promote tissue repair and healing. In biomaterial research, PRP is often incorporated into scaffolds to enhance their bioactivity, facilitating cell attachment, proliferation, and differentiation for improved tissue regeneration. However, inconsistencies in outcomes and variability across studies hinder its clinical translation. These challenges are primarily attributed to the lack of standardized reporting criteria for PRP characterization, which limits reproducibility and cross-study comparisons. Accurate characterization of PRP is essential for understanding its biological activity and therapeutic potential. Key parameters include platelet, white blood cell, and red blood cell concentrations. Recent classification systems, such as those proposed by the ISTH Subcommittee on Platelet Physiology, emphasize the importance of these parameters in categorizing PRP types. Establishing minimal reporting requirements helps address variability in PRP studies, ensuring consistency and transparency in the methodology and results. By adopting these standards as mandatory reporting requirements, researchers can reduce variability, enhance the credibility of their findings, and facilitate the development of standardized protocols for PRP-based therapies.

PRP or not PRP: Is the debate surrounding platelets-based blood-derived products evolving?

The increasing interest in biologic treatments for musculoskeletal disorders has led to the advancement of orthobiologics, particularly in non-operative care through injectable therapies. However, defining these treatments clearly is crucial for proper clinical application. Orthobiologics include biologic substances that enhance healing, such as cell-based therapies and blood-derived products. Among these, platelet-rich plasma (PRP) is widely used, but its classification remains complex due to variations in preparation methods, platelet concentration, leucocyte content, and activation techniques. Strictly, the term 'PRP' refers to plasma enriched in platelets relative to baseline blood levels. Yet, scientific debate persists regarding whether platelet count or enrichment is more significant in clinical outcomes. Additionally, leucocyte-rich and leucocyte-poor PRPs offer different therapeutic advantages depending on the target tissue, complicating standardization. Similarly, the presence of red blood cells is generally discouraged, given their association with joint inflammation. Beyond the classical 'PRP' formulations, alternative blood-derived products offer distinct biological effects. A standardized classification system is therefore essential for research and clinical application, emphasizing precise documentation of products' characteristics, including platelet count, activation state and bioactive molecule interactions. Understanding these variables and their impact on patient-specific conditions will refine orthopaedic regenerative strategies and optimize treatment efficacy.

Re-Evaluating Platelet-Rich Plasma Dosing Strategies in Sports Medicine: The Role of the "10 Billion Platelet Dose" in Optimizing Therapeutic Outcomes-A Narrative Review

Platelet-rich plasma (PRP) therapy is increasingly recognized as a promising treatment for musculoskeletal disorders, including osteoarthritis (OA), tendinopathy, and muscle injuries. This narrative review synthesizes the current literature to evaluate the efficacy of PRP, with a focus on platelet dosing strategies, leukocyte composition, and preparation protocols. Evidence suggests that optimal therapeutic outcomes are achieved when platelet doses exceed 3.5 billion per injection, with cumulative doses of 10-12 billion across multiple treatments. In intra-articular applications, leukocyte-poor PRP (LP-PRP), characterized by reduced neutrophil content, demonstrates superior efficacy compared to leukocyte-rich PRP (LR-PRP). However, its effectiveness in tendon and muscle regeneration remains a subject of debate. Preliminary data suggest that the inclusion of peripheral blood mononuclear cells (PBMNCs) may enhance PRP efficacy, though robust clinical trials are required to confirm these findings. Furthermore, red blood cell contamination and pre-activation have been identified as detrimental to PRP effectiveness, highlighting the need for standardized preparation protocols. This review emphasizes the importance of tailoring PRP formulations to patient-specific factors and musculoskeletal conditions. Future research should focus on refining PRP preparation techniques, identifying optimal leukocyte compositions, and establishing standardized guidelines to enhance clinical outcomes.

Platelet Lysate and Osteoarthritis of the Knee: A Review of Current Clinical Evidence

INTRODUCTION

Osteoarthritis (OA) of the knee affects millions of people with sizable socioeconomic burden. Conventional treatment modalities are prioritized, turning to surgical intervention only when they have failed. However, these traditional modalities have shortcomings, only aiming to reduce pain rather than targeting the underlying pathophysiology. Recently, the use of biologics, including autologous peripheral blood-derived orthobiologics (APBOs), has increased and demonstrated great promise for the management of knee OA. Platelet-rich plasma (PRP) is the most widely used APBO, but its efficacy is still uncertain, attributed to lack of standardized formulation protocols, characterization, and patient variables. To overcome the limitations posed by PRP, the use of other APBOs such as platelet lysate (PL) has been considered. This review summarizes the outcomes of clinical studies involving PL to manage OA of the knee.

METHODS

Multiple databases (Scopus, Embase, PubMed, and Web of Science) were searched employing terms "platelet lysate" and "knee osteoarthritis" for articles published in the English language to August 15, 2024, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Only three clinical studies fulfilled our search and inclusion criteria. Intra-articular injection of three doses of PL injected every 3-4 weeks is safe and efficacious, resulting in statistically significant improvements in different patient-reported outcome measures at 6-12 months follow-up.

CONCLUSION

The existing published peer-reviewed literature suggests that intra-articular injection of PL is safe and can decrease pain and increase function in patients with knee OA. Nonetheless, given the dearth of pertinent literature, more adequately powered, multicenter, prospective, non-randomized and randomized controlled studies with extended follow-up are needed to confirm the effectiveness of PL in knee OA. Further comparative studies to help clinicians in choosing the best APBO for knee OA treatment are also warranted.

Autologous Peripheral Blood-Derived Orthobiologics for the Management of Hip Osteoarthritis: A Systematic Review of Current Clinical Evidence

Osteoarthritis (OA) of the hip affects millions of people with a sizable health-related economic burden. Conventional treatment modalities are prioritized, turning to surgical intervention only when they have failed. Nevertheless, these approaches have flaws, regularly trying to provide symptomatic pain relief instead of focusing on the underlying etiology. The last two decades have seen a significant increase in the use of autologous peripheral blood-derived orthobiologics (APBOs) for managing musculoskeletal disorders, including OA of the hip. Platelet-rich plasma (PRP) is the most regularly used APBO. Yet, studies have shown its inefficacy in improving pain and function along with a high incidence of reporting bias in systematic reviews and meta-analyses involving PRP injections for hip OA. Thus, the potential of using other APBOs, including platelet lysate (PL), autologous conditioned serum (ACS), gold-induced cytokine (GOLDIC), plasma rich in growth factors (PRGF), autologous protein solution (APS), and hyperacute serum (HS), for managing OA of the hip was investigated. This review summarizes the results of clinical studies involving the mentioned APBOs to manage OA of the hip. Multiple databases (Scopus, Embase, PubMed, and Web of Science) were searched employing terms for these 'APBOs' and 'OA of the hip' for articles published in the English language till September 21, 2024, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only two articles fit the scope of our study, and both included articles involved the use of ACS. No clinical studies involving the use of PL, GOLDIC, PRGF, APS, and HS were identified. No ongoing clinical trials were listed on any of the searched registers involving the use of the aforesaid APBOs. Intra-articular administration of ACS is safe and can reduce pain in patients with OA of the hip. Nonetheless, given the dearth of pertinent literature and limitations of included articles, more adequately powered, prospective, multicenter, controlled, open-label or blinded, randomized, and non-randomized trials with extended follow-up are necessary to determine the efficacy of various APBOs for managing hip OA. Further comparative studies to assist clinicians in finding the ideal APBO for the treatment of OA of the hip are needed.

Leukocyte-Poor Platelet-Rich Plasma for the Management of Knee Osteoarthritis: A Retrospective Study With 12 Months of Follow-Up

Introduction The knee, the most frequently affected joint in osteoarthritis (OA), impacts the life quality of millions of individuals globally, resulting in a considerable healthcare burden. Conservative treatments are preferred, turning to surgical intervention when necessary. Nonetheless, these conventional modalities have drawbacks. Recently, the use of regenerative medicine therapies, including autologous peripheral blood-derived orthobiologics (APBOs), such as leukocyte-poor platelet-rich plasma (LP-PRP), has evolved and demonstrated the ability to manage knee OA. The primary objective of this investigation was to evaluate the efficacy of LP-PRP via widely used patient-reported outcome measures (PROMs) in grade I or II (on the Kellgren-Lawrence scale) knee OA patients. The secondary objective was to characterize the formulated LP-PRP and determine the efficiency of the leukodepletion filter used for leukocyte removal and platelet recovery. Methods This investigation was a retrospective analysis of data collected from patients treated at a single center over a period of 15 months. Data from 40 patients included in this study were intra-articularly injected with 3mL of formulated LP-PRP under ultrasound guidance. PROMs questionnaires, including Kujala and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, were used and responses were documented at baseline and up to 12 months follow-up. The characterization of the formulated LP-PRP and the efficiency of the leukodepletion filter in removing leukocytes and recovering platelets were assessed via complete blood count (CBC) analysis. Results The intra-articular administration of LP-PRP resulted in statistically significant improvements in Kujala and WOMAC scores in patients with Grade I or II OA of the knee at all follow-up time points (four to 12 months) compared to the respective baseline scores. The subgroup analysis showed significant improvements in Kujala and WOMAC scores in both male and female grade I or II knee OA patients with or without comorbidities, including diabetes and/or hypertension. The characterization of formulated PRP showed platelet concentration to be at least 6x compared to the baseline whole blood levels, the absolute platelet count to be at least 5 billion, and total leukocytes, lymphocytes, neutrophils, and RBCs were depleted by over 88%, 82%, 98%, and 98%, respectively. In addition, the utilization of the PuriBlood leukocyte reduction filter (Puriblood Medical Co. Ltd., Baoshan Township, Taiwan) led to the depletion of approximately 93% of leukocytes and the recovery of about 83% of platelets. Conclusions Administration of LP-PRP resulted in significant improvements in pain and function of patients suffering from grade I or II OA of the knee. In addition, the leukodepletion filter used to formulate LP-PRP, successfully resulted in the depletion of leukocytes while recovering the platelets. More sufficiently powered, multi-center, prospective, non-randomized, and randomized controlled trials with long-term follow-up are needed to further establish the effectiveness of this formulation in knee OA patients.

High-Dose Neutrophil-Depleted Platelet-Rich Plasma Therapy for Knee Osteoarthritis: A Retrospective Study

Background/Objectives: Encouraging results have been reported for Platelet-Rich Plasma (PRP) treatment for knee osteoarthritis (KOA). This study reports the efficacy and safety of a high dose of neutrophile and red-blood-cell-depleted PRP to treat patients with KOA. Methods: A total of 212 consecutive patients diagnosed with Kellgren-Lawrence (KL) grading 1-3 KOA chronic knee pain for at least 1 year were treated with three injections at 15-day intervals with a high dose of neutrophil-depleted PRP (4 billion platelets). Clinical outcomes were retrospectively recorded as the percentage of responders at 3-, 6-, and 12-month follow-up, following the OMERACT-OARSI criteria. Pain, through the VAS score and WOMAC score, was also been recorded. Results: A total of 4 mL of PRP containing 4 × 109 platelets was obtained by single-spin centrifugation and injected intra-articularly into each patient with no preactivation. The overall responder rate of patients responding to the OMERACT-OARSI criteria at 3, 6, and 12 months was 68.9%, 72.7%, and 70.6%, respectively. A significant improvement in VAS and WOMAC scores at 3-, 6-, and 12-month follow-up compared to the pretreatment value (p < 0.01) was observed. The lowest VAS score was observed at 6 months overall and in all three KL-graded groups. The KL2 groups showed the best results regarding pain reduction and their WOMAC score at 6 months (p < 0.01). Conclusions: For KL1-3 KOA, a high dosage of neutrophil-depleted PRP is a successful treatment. It has long-lasting effects that last up to one year, relieves symptoms, and may slow the advancement of the disease.

Growth Factor Concentrate (GFC) for the Management of Osteoarthritis of the Knee: A Systematic Review

Introduction

The knee is the most commonly affected joint in osteoarthritis (OA), affecting millions of people worldwide. Knee OA significantly impacts the activities of daily living (ADL) along with affecting overall quality of life of patients (QoL), thereby leading to substantial socio-economic burden. Conservative therapies are prioritized, resorting to surgery only when needed. However, these traditional approaches have limitations. Regenerative medicine, involving the use of orthobiologics, including autologous peripheral blood-derived orthobiologics such as growth factor concentrate (GFC), has evolved and shown potential for managing knee OA. The primary goal of this review is to summarize the results of in vitro, preclinical and clinical studies involving GFC for the management of knee OA.

Methods

Multiple databases (PubMed, Scopus, Google Scholar, Web of Science and Embase) were searched applying terms for the intervention 'GFC' and treatment 'knee OA' for the studies published in the English language to March 10, 2024.

Results

Only three clinical studies met our pre-defined criteria and were included in this review.

Conclusion

Intra-articular administration of GFC is safe and potentially efficacious to manage OA of the knee. More, adequately powered, multi-center, prospective, RCTs are warranted to demonstrate the long-term effectiveness of GFC in patients suffering from mild-to-moderate knee OA and to justify its routine clinical use. Further studies evaluating the efficacy of GFC compared to other orthobiologics are also required to allow physicians/surgeons to choose the optimal orthobiologic for the treatment of OA of the knee.

Allogenic Platelet-Rich Plasma for the Treatment of Adhesive Capsulitis

Adhesive capsulitis (AC) is a common shoulder disorder leading to pain and restricted range of motion (ROM) and affects the patient's activities of daily living (ADL) and overall quality of life (QoL). Conservative therapies are prioritized, resorting to surgical intervention only when necessary. Unfortunately, these modalities have limitations and do not address the underlying pathological cause of AC. The use of autologous biologics, such as platelet-rich plasma (PRP), has evolved and shown promise for managing musculoskeletal (MSK) injuries, including AC. However, subpar functional outcomes have led clinicians to question the long-term efficacy of autologous PRP. To circumvent this, the possibility of utilizing a standardized and well-characterized allogenic PRP for AC has been explored. In this manuscript, we qualitatively present in vitro, pre-clinical, clinical, and ongoing studies investigating the varied applications of allogenic PRP for the management of AC. The results demonstrated that allogenic PRP acts in a pleiotropic manner and decreases pro-inflammatory cytokines only in the inflammatory condition. In addition, the administration of allogenic PRP is safe and potentially efficacious, in terms of reducing pain and improving range of motion, shoulder strength, and function, in non-surgical management of AC. Nonetheless, more pre-clinical studies and adequately powered, multicenter, prospective, non-randomized, and randomized controlled trials with longer follow-up are warranted to further establish the safety and efficacy of allogenic PRP and justify its routine clinical use.