The use of platelets in regenerative medicine and proposal for a new classification system: guidance from the SSC of the ISTH

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.

Platelet like cells differentiated from human adipose derived mesenchymal stem cells promote healing of tendinopathy in rats

Tendon and ligament disorders, such as tendinopathy, cause pain and limit levels of activities of daily living. Thus, devising methods to heal them is crucial. Although treatment with autologous platelet rich plasma (PRP) is reportedly useful against tendon injury, PRP requires blood sampling and its quality varies. Here we show that platelet-like cells (ASCL-PLCs) derived from a heterologous human adipose-derived mesenchymal stem cell line (ASCL) promote significant tendon repair in a collagenase-induced injury model in rat Achilles tendons. Single administration of human ASCL-PLCs to rat Achilles tendon after 2 weeks of collagenase treatment significantly increased tendon strength and improved semi-quantitative histological evaluation scores in 4 weeks relative to PBS-treated controls. Moreover, xeno-graft reactions were not evident in ASCL-PLC-administered rats. In vitro, ASCL-PLC treatment significantly upregulated Col1a1, Lox and Mkx gene expression in NIH3T3 fibroblasts and activated ERK signaling. Overall, ASCL-PLCs could serve as a useful tool to repair injured tendons and treat tendinopathy. This approach eliminates the need for blood sampling, ensures consistent quality, supports xeno-transplantation, and increases injured tendon strength.

Treatment tactic of canine cranial cruciate ligament rupture management: A 28-day comparative analysis of ACP and NSAID induced effects on the serum MMP-3 levels and clinical outcomes

Cranial cruciate ligament rupture (CrCLR) is a common stifle joint pathology among dogs, leading to osteoarthritis and painfulness. Non-surgical treatment options often represent the usage of non-steroidal anti-inflammatory drugs for 14 days (NSAIDs), but autologous conditioned plasma (ACP) shows promising results in managing various orthopaedic conditions, decreasing inflammation, and improving the clinical outcome in dogs. This study aimed to determine the differences in MMP-3 serum levels and the clinical outcomes between differently treated cranial cruciate rupture cases. For this purpose, we used two different treatment methods for managing canine cranial cruciate ligament rupture (minimally invasive ACP injection or oral NSAIDs), and evaluated the clinical outcomes, indicating the quality of life, and the MMP-3 serum levels over a period of 28 days. The findings of this investigation indicate that ACP has better efficacy than two weeks of NSAIDs in inflammation reduction, clinical outcome improvement, and the allowance of a longer duration of activity after 28 days.

Systematic Review of Randomized Controlled Trials Evaluating the Use of Platelet-Rich Plasma for Knee Osteoarthritis: Adherence to Minimum Information for Studies Evaluating Biologics in Orthopaedics

BACKGROUND

The Minimum Information for Studies Evaluating Biologics in Orthopedics (MIBO) guidelines were developed in May 2017 to encourage improved reporting standards, promote increased transparency and reproducibility, and enhance clinical evaluation capabilities. The MIBO guidelines consist of 23 checklist items considered necessary to critically appraise clinical studies evaluating platelet-rich plasma (PRP).

PURPOSE

To assess randomized controlled trials that evaluated PRP for the treatment of knee osteoarthritis in order to systematically review their adherence to the MIBO guidelines.

STUDY DESIGN

Systematic review. Level 1a.

METHODS

A search was performed following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The inclusion criteria were randomized controlled trials reporting on knee osteoarthritis treated with intra-articular PRP. The studies were categorized into pre-, peri-, and post-MIBO groups based on the start date of data collection. The overall MIBO scores, defined as percentage of checklist items out of the 23 checklist items reported in 1 study, individual item scores, defined as percentage of studies reporting the checklist item within a specified group, and overall item score defined as the average of the individual item scores from all the included studies were calculated.

RESULTS

The review included 87 studies (7925 patients; 8118 knees). Of these, 51 studies were assigned to the pre-MIBO group, 19 studies to the peri-MIBO group, and 17 studies to the post-MIBO group. The overall MIBO score was 72%. No statistically significant differences in MIBO scores were found among the 3 MIBO groups (P = .345). The majority of the studies (62 studies; 71%) had MIBO scores <80%. MIBO items with particularly low item scores included reporting of whole-blood characteristics (20%), platelet recovery rate (22%), PRP analysis (30%), and PRP activation (47%). No significant difference among the 3 MIBO groups was found for the item scores except for the reporting of the recipient details (P = .012).

CONCLUSION

This study highlights the deficiencies in adherence to the MIBO guidelines, particularly in reporting key variables such as whole-blood characteristics, platelet recovery rate, PRP analysis, and PRP activation. These findings suggest that the publication of the MIBO guidelines has not resulted in improved reporting practices in studies investigating intra-articular PRP for the treatment of knee osteoarthritis.

Retrospective Analysis of Short-Term Responses to PRP Injections for Patients With Vocal Fold Scars and Presbylaryngis

Vocal fold scarring and presbylarynx significantly impair voice quality, leading to a decline in patients' quality of life. These pathologies represent considerable challenges for laryngologists. Traditional treatments often produce suboptimal outcomes. Platelet-rich plasma (PRP) is an innovative, minimally invasive treatment that uses autologous biological material rich in growth factors and platelets, with positive effects on tissue regeneration and repair. Based on its promising effects, we started using PRP as a therapeutic option in vocal folds scars and presbylarynx. We performed a retrospective study on the efficacy and clinical outcomes of PRP injections performed in these patients. Between October 2021 and November 2023, 48 patients (35 women, 13 men; mean age 53 ± 15 years) were treated with PRP for a total of 109 injections for acute or chronic vocal fold lesions or presbylaryngis. PRP preparation followed a standardized protocol. The mean volume of PRP injected per vocal fold was 0.57 ± 0.30 mL, with high platelet purity (95.05% ± 3.48) found in PRP biological characterization. No adverse events were reported. The vocal outcomes assessed 1 month after the treatment found no modification in the acoustic parameters, but a significant improvement in the perceptual voice analysis on the G (P < 0.001), R (P = 0.005), and B (P = 0.008) of the GRB scale, and a clinical improvement on videolaryngostroboscopy for 62.5% of the patients. Most importantly, 70.8% of the patients reported subjective improvement with an average reduction in VHI-30 score of 10.79 points, with 32% of patients achieving clinically significant improvement (≥18 points). PRP injections demonstrate promising efficacy and safety in vocal fold scars and presbylaryngis treatment, with a significant improvement in perceptual voice analysis and subjective assessments. Further studies with larger cohorts and control groups are needed to confirm these findings and optimize PRP therapy protocols.

Beneficial Effects of Infiltration of Platelet-Rich Plasma in the Endometrium

Platelet-rich plasma (PRP) is a concentrated product of autologous plasma platelets. It promotes the repair of tissues with low healing potential by providing supraphysiological amounts of essential growth factors and has recently become more popular in endometrial repair, achieving exciting clinical results. PRP treatment has proven to improve fertility outcomes in patients with a poor endometrial environment. However, the mechanism is not yet clear. Previous preclinical models also showed that PRP treatment decreased the expression of inflammatory markers and fibrosis, increased the endometrial proliferation rate and gene expression, and enhanced the pregnancy rate. The modulation of the endometrial immune environment and endometrial microbial community by PRP treatment appeared to be the key mechanism by which it improved endometrial receptivity. This review summarized the potential of adult PRP based on its composition and applications and the biological mechanisms and biological modifications in the endometrium after PRP instillation in preclinical models.

PRP Injections for the Treatment of Knee Osteoarthritis: The Improvement Is Clinically Significant and Influenced by Platelet Concentration: A Meta-analysis of Randomized Controlled Trials

BACKGROUND

Platelet-rich plasma (PRP) has emerged as a promising therapeutic intervention for knee osteoarthritis (OA), attracting substantial clinical and research attention. However, the clinical relevance of the treatment benefit remains controversial.

PURPOSE

To evaluate the effectiveness of PRP compared with placebo in patients with knee OA in terms of minimal clinically important difference (MCID) and to investigate the possible influence of platelet concentration on the clinical outcome.

STUDY DESIGN

Meta-analysis. Level of evidence 1.

METHODS

The search was conducted on 5 databases (PubMed, Cochrane Library, Scopus, Embase, Web of Science) using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Inclusion criteria were randomized controlled trials comparing PRP and placebo injections to treat knee OA, written in the English language, with no time limitation. The effects were quantified at 1-, 3-, 6-, and 12-month follow-up points. Visual analog scale (VAS) for pain and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were used, with subanalyses based on platelet concentration performed using a 1,000,000 ± 20% platelets/µL cutoff. The MCID values (VAS, 1.37; WOMAC, 6.4) were used to interpret clinical improvement. The articles' quality was assessed using the Revised Tool for Risk of Bias in Randomized Trials and the Grading of Recommendations Assessment, Development and Evaluation guidelines.

RESULTS

Among the 5499 articles retrieved, 18 randomized controlled trials (1995 patients) were included. PRP presented statistically superior improvements in VAS and WOMAC scores compared with placebo at all follow-up points, exceeding the MCID at 3- and 6-month follow-up points for VAS and at all follow-up points for WOMAC. The subanalysis based on platelet concentration showed that high-platelet PRP provided clinically significant pain relief with the improvement exceeding the MCID compared with placebo at 3-, 6-, and 12-month follow-up points. In contrast, low-platelet PRP failed to offer a clinically perceivable benefit in terms of VAS score. WOMAC results showed that both products provided a clinically significant improvement at 3 and 6 months of follow-up. This benefit was maintained up to the 12-month follow-up in the high-platelet group but not in the low-platelet group, where the improvement compared with placebo did not reach statistical significance.

CONCLUSION

This meta-analysis showed that PRP offered clinically relevant functional improvement at 1-, 3-, 6-, and 12-month follow-up points and pain relief at 3- and 6-month follow-up points compared with placebo for the treatment of knee OA. Platelet concentration was found to influence treatment efficacy, with high-platelet PRP providing superior pain relief and more durable functional improvement compared with low-platelet PRP.

Minimum reporting guidelines for platelet-rich plasma in veterinary regenerative medicine

Platelet concentrates such as platelet-rich plasma (PRP) are widely used in veterinary regenerative medicine and transfusion therapy. However, the therapeutic efficacy of PRP is highly dependent on its precise characterization, cellular composition, and preparation methods. Without proper standardization, PRP treatments can yield inconsistent results, undermining their clinical utility. A recent study in Veterinary Research Communications underscores the importance of pH measurement as a key quality control parameter for platelet concentrates, including PRP, in veterinary blood banks. Building on these findings and our own recent experience, we propose revised minimum reporting guidelines for the use of PRP in veterinary regenerative medicine. Adherence to minimum reporting guidelines is essential to ensure reproducibility and reduce heterogeneity in PRP therapies. Future research should focus on species-specific protocols and advanced characterization techniques to enhance the therapeutic potential of PRP. By addressing these challenges, PRP can become a cornerstone of regenerative therapies in veterinary medicine, offering safe and effective treatment options for various diseases and disorders.

Platelet extracellular vesicles-loaded hydrogel bandages for personalized wound care

Autologous or allogeneic platelet-derived extracellular vesicles (pEVs) show potential in enhancing tissue recovery and healing chronic wounds. pEVs promote neovascularization and cell migration while reducing inflammation, oxidative stress, and scarring. However, their efficacy in clinical settings is challenged by their susceptibility to washout by wound exudate. Hydrogel-based bandages are effective carriers that stabilize pEVs for optimal personalized wound care. These bandages can be tailored for easy removal to minimize damage to regenerated tissue and can incorporate antibacterial or moisture-retaining properties. Furthermore, the possibility of integrating sensors in the wound bed will enable a theragnostic approach to healing. This review explores advancements in pEV-loaded hydrogels and their potential for personalized clinical applications.

Platelet-rich plasma effects on in vitro cells derived from pediatric patients with andrological diseases

Undescended testis and testicular torsion represent two frequent andrological diseases that affect the pediatric age. Despite these testicular disorders having different causes, they both negatively influence fertility in adulthood mainly due to the accumulation of reactive oxygen species (ROS), which represents the primary molecular damage underlying their long-term effects. The gold standard of treatment for both pathologies is surgery; however, it cannot guarantee an optimal fertility outcome in all clinical cases, underscoring the need to identify effective adjuvant therapies that may target the augmented ROS levels. For this aim, we investigated the pro-proliferative and anti-oxidant effects of PRP (platelet-rich plasma), a hemoderivative product used in regenerative medicine. We confirmed the increased oxidative status in testicular tissue by directly analyzing patients' biopsies with mass spectrometry and highlighting that three antioxidant proteins are significantly overexpressed compared to healthy testicles. Afterward, we in vitro treated cells derived from patients with cryptorchidism or testicular torsion with PRP, showing that it consistently decreases ROS levels and slightly induces cell proliferation. This study supports the potential use of PRP in patients with testis torsion or cryptorchidism, encouraging its future clinical application as adjuvant therapy to preserve the functionality of this organ by decreasing its ROS levels.

Efficacy of platelet-rich plasma in meniscal repair surgery: a systematic review of randomized controlled trials

PURPOSE

This study's primary objective was to evaluate the effectiveness of platelet-rich plasma (PRP) administration for meniscal injuries treated with meniscal repair procedures (sutures), using radiologic measures and clinical scales. The secondary objective was to identify potential bias-inducing elements in the analyzed studies.

METHODS

In December 2023, a systematic search was conducted in PubMed, Cochrane, Embase, and Scopus for randomized controlled trials. This review compares PRP with placebo. Three studies were finally selected. The risk of bias was assessed using Cochrane's Risk of Bias Tool 2. Radiologic evaluation of meniscal healing was measured with magnetic resonance imaging (MRI) and arthroscopic studies, while clinical evaluation was performed using four scales [Knee Injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS), International Knee Documentation Committee Subjective Knee Form (IKDC), and Western Ontario and McMaster Universities Index (WOMAC)] and by recording the incidence of complications.

RESULTS

The three selected studies included 139 patients; of these, 76 (54.7%) were randomly assigned to the intervention group (PRP injection) and 63 (45.3%) to the control group (placebo). The mean age of the intervention group was 37.4 ± 7.5 years, while the mean age of the control group was 36.5 ± 9.2 years. There were 41 female patients (29.5%). The median follow-up duration was 27.58 ± 17.3 months. MRI evaluation did not show a significant improvement in the PRP group in any of the studies (p-value = 0.41-0.54). However, when assessed by the cumulative evaluation of MRI and arthroscopy, the cumulative failure rate was significantly better in the PRP group (p-value = 0.04-0.048). One study that evaluated isolated arthroscopy also showed significant improvement in the PRP group (p = 0.003). Regarding the VAS scale, no study demonstrated a significant difference, except for one study that showed significant improvement after 6 months and in the difference between the 3rd and 6th months. The KOOS scale yielded conflicting results; one study showed no significant difference, while the other two indicated significant improvement. The IKDC and WOMAC scales were evaluated in two studies, showing opposite results. All included studies reported no complications, and one study indicated no increased risk in the treatment group.

CONCLUSIONS

The results of this review indicate the necessity for further studies to make a definitive statement about the effectiveness of PRP administration in meniscal repair processes. Level of evidence Systematic review and meta-analysis of articles of level 1.

Comparison of bioactive substances in novel-developed freeze-dried platelet-rich plasma (PRP) and activated normal PRP, and investigation of bioactive substance levels after long-term storage

Introduction

In recent years, biotherapy in orthopedics has become widespread, and platelet-rich plasma (PRP) has been readily used to treat sports injuries and osteoarthritis. Production of freeze-dried PRP (PRP-FD) results in PRP that is in powder form, allowing it to be stored for long periods at room temperature. Using this technology, we have developed Valuable Platelet-Derived Factor Concentrate Freeze Dry (VFD). However, whether VFD contains sufficient levels of bioactive substances (BS) remains unknown and retains the same levels of BS during long-term storage. In this study, we examined whether VFD contains sufficient amounts of BS and whether they retain these BS levels during long-term storage.

Methods

Peripheral blood was collected from 10 healthy men (mean ± SD: 46.5 ± 15 years old) and various BS, including transforming growth factor β (TGF-β), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), tissue inhibitors of metalloproteinases-1 (TIMP-1), interleukin-1 receptor antagonist (IL-1ra), matrix metallopeptidase-9 (MMP-9), and interleukin-6 (IL-6), were compared between VFD and normal PRP samples, including both leukocyte-rich PRP (LR-PRP) and leukocyte-poor PRP (LP-PRP). VFD was prepared using two rounds of centrifugation. LP-PRP and LR-PRP were activated by freezing and thawing before measurement. To evaluate the effects of long-term storage, the BS of VFD purified from five professional football players was compared between baseline and 1 year after storage.

Results

In terms of the growth factors, the TGF-β and EGF levels were higher in LR-PRP than in VFD and LP-PRP (p < 0.05), while the bFGF levels were higher in VFD than in the LR-PRP and LP-PRP groups (p < 0.01). In terms of anti-inflammatory cytokines, the TIMP-1 level was lower in VFD than that in the other groups (p < 0.01), whereas the IL-1ra levels were higher in VFD than those in LP-PRP (p < 0.05) and lower than those in LR-PRP (p < 0.01). In terms of inflammatory enzymes and cytokines, the IL-1ra level was higher in VFD than that in LP-PRP (p < 0.05) and lower than that in LR-PRP (p < 0.01), whereas the IL-6 levels did not differ among the groups. Furthermore, the TGF-β, bFGF, TIMP-1, and IL-1ra levels were 5.61 → 3.38 (x103 pg/μL), 61.0 → 63.0 (pg/μL), 3.4 → 2.7 (x105 pg/μL), and 14.9 → 14.5 (x103 pg/μL) at baseline and 1 year later, respectively. No significant differences in the BS levels were observed between baseline and 1 year after storage.

Conclusions

The VFD samples prepared in this study exhibited higher levels of anti-inflammatory cytokines than LP-PRP and contained growth factor levels similar to LP-PRP and LR-PRP. In addition, the BS levels in VFD samples were maintained after one year of storage. These results suggest that VFD can be prepared and stored and may serve as a novel treatment strategy for sports injuries in high-risk groups, such as athletes.

Full-thickness burn scar treatment using a combination of microneedling and platelet-rich plasma in animal model

Microneedling (MA) and platelet-rich plasma (PRP) therapies have shown potential for enhancing scar repair through collagen production and growth factor release, yet their effects on full-thickness burn scars remain underexplored. This study evaluated the impact of MA, PRP, and combined MA + PRP treatments on scar healing in a rat model of full-thickness burns. Fifty adult rats were divided into four groups: control, MA, PRP, and MA + PRP. Treatments were administered 21 days post-burn, and animals were evaluated at 14- and 21-days post-treatment. Macroscopic, histopathological, and morphometric analyses were performed to assess epithelialization, extracellular matrix (ECM) organization, and collagen deposition. The combination of MA + PRP demonstrated superior outcomes, showing enhanced ECM organization, significant collagen deposition, increased angiogenesis, and an improved inflammatory profile with mononuclear cell infiltration. Morphometric analysis confirmed a substantial increase in collagen content, particularly in the MA + PRP group, supporting improved tissue remodeling and scar maturation. These findings suggest that combined MA + PRP therapy may be a promising approach for promoting effective and accelerated burn scar healing. Further research is warranted to optimize protocols for clinical application.

Update on Platelet-Rich Plasma and Platelet-Rich Fibrin for Dermatologic Surgery: Addressing Knowns and Unknowns

BACKGROUND

Autologous and allogeneic platelet-rich plasma (PRP) in addition to its derivatives, such as platelet-rich fibrin (PRF), are broadly accepted therapeutic approaches in orthopedics, otolaryngology, sports medicine, plastic surgery, and oral and maxillofacial surgery. However, the absence of expert consensus, standardized protocols, and varying outcomes pose challenges to their broader acceptance in cosmetic dermatology and dermatologic surgery.

OBJECTIVE

To offer a contemporary literature overview of PRP and PRF, focusing on fundamental aspects of the technology, diversity of commercially accessible systems, and shed light on present-day controversies within the field.

METHODS

A systemic review of PRP and PRF literature was conducted, utilizing search engine databases: Cochrane Database of Systematic Reviews, Embase, Ovid MEDLINE, and PubMed. Emphasis was placed on scrutinizing higher level-of-evidence articles, specifically randomized control trials, systematic reviews, and meta-analyses (Level 1A-2A), with particular emphasis on recent data that have not been well reviewed in other publications from January 2022 to May 2024.

RESULTS

An increasing body of literature affirms advantages of PRP products in dermatology, spanning wound care, facial rejuvenation, scar revision, and hair growth.

CONCLUSION

A foundational understanding of variation in preparation protocol, outcomes, and timing of administration is needed to better comprehend market dynamics, patient demand, and strategies for integrating PRP into dermatologic practice.

Highly concentrated collagen/chondroitin sulfate scaffold with platelet-rich plasma promotes bone-exposed wound healing in porcine

In the case of wounds with exposed bone, it is essential to provide not only scaffolds with sufficient mechanical strength for protection, but also environments that are conducive to the regeneration of tissues and blood vessels. Despite the excellent biocompatibility and biodegradability of collagen and chondroitin sulfate, they display poor mechanical strength and rapid degradation rates. In contrast to previous methodologies that augmented the mechanical properties of biomaterials through the incorporation of additional substances, this investigation exclusively enhanced the mechanical strength of collagen/chondroitin sulfate scaffolds by modulating collagen concentrations. Furthermore, platelet-rich plasma (PRP) was employed to establish optimal conditions for vascular and tissue regeneration at the wound site. High-concentration collagen/chondroitin sulfate (H C-S) scaffolds were synthesized using high-speed centrifugation and combined with PRP, and their effects on endothelial cell proliferation were assessed. A porcine model of bone-exposed wounds was developed to investigate the healing effects and mechanisms. The experimental results indicated that scaffolds with increased collagen concentration significantly enhanced both tensile and compressive moduli. The combination of H C-S scaffolds with PRP markedly promoted endothelial cell proliferation. In vivo experiments demonstrated that this combination significantly accelerated the healing of porcine bone-exposed wounds and promoted vascular regeneration. This represents a promising strategy for promoting tissue regeneration that is worthy of further exploration and clinical application.

Mechanisms and applications of the regenerative capacity of platelets-based therapy in knee osteoarthritis

Osteoarthritis (OA) is the most prevalent joint disease in the elderly population and its substantial morbidity and disability impose a heavy economic burden on patients and society. Knee osteoarthritis (KOA) is the most common subtype of OA, which is characterized by damage to progressive articular cartilage, synovitis, and subchondral bone sclerosis. Most current treatments for OA are palliative, primarily aim at symptom management, and do not prevent the progression of the disease or restore degraded cartilage. The activation of α-granules in platelets releases various growth factors that are involved in multiple stages of tissue repair, suggesting potential for disease modification. In recent years, platelet-based therapies, such as platelet-rich plasma, platelet-rich fibrin, and platelet lysates, have emerged as promising regenerative treatments for KOA, but their related effects and mechanisms are still unclear. Therefore, this review aims to summarize the biological characteristics and functions of platelets, classify the products of platelet-based therapy and related preparation methods. Moreover, we summarize the basic research of platelet-based regeneration strategies for KOA and discuss the cellular effects and molecular mechanisms. Further, we describe the general clinical application of platelet-based therapy in the treatment of KOA and the results of the meta-analysis of randomized controlled trials.

Tibial transverse transport combined with platelet-rich plasma sustained-release microspheres activates the VEGFA/VEGFR2 pathway to promote microcirculatory reconstruction in diabetic foot ulcer

This study proposes to investigate the therapeutic efficacy and mechanism of combining tibial transverse transport (TTT) with platelet-rich plasma (PRP) for diabetic foot ulcer (DFU). The diabetic rabbit model was constructed with Streptozotocin, which was intervened with TTT and PRP. PRP injection combined with TTT significantly promoted vascularisation and enhanced CD31, VEGFA, and VEGFR2 expressions compared to traditional TTT. However, the VEGFR2 inhibitor suppressed these phenomena. In the in vitro injury model, PRP reversed the diminished human umbilical vein endothelial cells (HUVECs) function and vascularisation caused by high-glucose damage. Additionally, PRP reduced inflammation and oxidative stress (approximately 47% ROS level) and enhanced VEGFA and VEGFR2 expression in HUVECs. However, the knockdown of VEGFR2 reversed the effect of PRP. In conclusion, TTT combined with intraosseous flap injection of PRP sustained-release microspheres activated the VEGFA/VEGFR2 pathway to promote microcirculatory reconstruction in DFU. These findings may provide new potential therapeutic strategies for DFU.

Not all platelet-rich plasma are created equal

PURPOSE OF REVIEW

This review aims to elucidate potential variations in clinical outcomes resulting from the use of different types of platelet-rich plasma (PRPs) in reproductive medicine. It seeks to explore the reasons behind the diverse results reported in various studies and assess the general features distinguishing different PRP formulations.

RECENT FINDINGS

PRPs have found applications across diverse medical fields, generating controversy due to the variability in outcomes. The field of reproductive medicine, despite its limited published studies, is encountering a similar challenge as it integrates these treatments.

SUMMARY

The multitude of PRP product brands in the market, coupled with 'home-made' PRPs, poses a significant barrier to establishing a common protocol for the preparation of standardized PRP products. This impediment hinders widespread adoption by clinicians, particularly in endometrial or ovarian treatments. Drawing from evidence in other medical disciplines, this review endeavors to compile essential characteristics that PRPs must possess, aiming to mitigate the impact of variables affecting results in forthcoming studies.

Ultrasound-Guided Subfascial Platelet-Rich Plasma Injections Versus Enthesis Needling for Greater Trochanteric Pain Syndrome: A Randomized Controlled Trial

Background

Greater trochanteric pain syndrome (GTPS) is characterized by gluteal enthesopathy involving the peritrochanteric space and associated with chronic pain and functional impairment. A corticosteroid injection in the trochanteric bursa is the usual palliative treatment for pain. However, it is important to investigate treatment options that will relieve pain in the peritrochanteric space.

Purpose

To compare the clinical efficacy of subfascial platelet-rich plasma (PRP) injection and enthesis needling for GTPS.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

A total of 92 patients (90% women; mean age, 55 years old; mean body mass index, 25.3 kg/m2) were randomly divided into a subfascial PRP injection group and an enthesis needling group. Descriptive data and radiographic measurements of the pelvis-including leg-length difference, pelvic width difference, and pelvic trochanteric index-were recorded. The primary outcome measures were the Hip Outcome Score (HOS) activities of daily living (HOS-ADL) and sports-specific (HOS-SS) subscales and the visual analog scale for pain at 3, 6, and 12 months posttreatment. In addition, we evaluated the presence or absence of ultrasound characteristics (fascia nodules, trochanteric bursa distension, and calcium deposits) over time in response to treatment.

Results

Baseline demographic and radiological characteristics were similar between the groups. The PRP group saw significantly greater improvement from baseline to 12 months posttreatment on the HOS-SS subscore compared with the needling group (32.09 [95% CI, 28.99-40.20] vs 20.52 [95% CI, 11.99-29.05]; P = .048). At 3 months, 60% of patients in the PRP group versus 33.3% in the needling group had a reduction in pain compared with a baseline of >20% (P = .040). After subfascial PRP injection, fewer patients had a fascia nodule over the trochanter and/or bursa distension (P = .006 and P = .004, respectively). The pelvic trochanteric index was predictive of HOS-ADL and HOS-SS outcomes (P = .011 and P = .022, respectively). The interaction between treatment modality and fascia nodule influenced HOS-ADL and HOS-SS outcomes (P = .021 and P = .023) as well as the interactions of treatment modality, fascia nodules, and calcifications (P = .027).

Conclusion

Both subfascial PRP injection and enthesis needling resulted in clinical improvements, but the improvement in the HOS-SS was greater in the PRP group.

Registration

NCT04231357 (ClinicalTrials.gov identifier).

Plasma Gel Matrix as a Promising Carrier of Epigallocatechin Gallate for Regenerative Medicine

Plasma gel (PG) is a protein matrix prepared from platelet-poor plasma and can be utilized as a drug carrier for controlled release. We previously demonstrated its applicability as a carrier of polyphosphate. Epigallocatechin-3-gallate (EGCG) is the main flavonoid found in green tea and functions as a strong antioxidant. To explore the applicability of PG as an EGCG carrier, we examined the release of EGCG from the PG matrix using an in vitro system. Pooled platelet-poor plasma (PPP) was prepared from four healthy adult male donors, mixed with EGCG, and heated at 75 °C for 10 or 20 min to prepare the PG matrix. The PG-EGCG matrix was incubated in PBS at 37 °C, and the EGCG released into PBS was determined using spectrophotometry. The antioxidant capacity was determined based on the principle of the iodine decolorization reaction. EGCG precipitated and incorporated into the PG matrix during thermal preparation. Trypsin, used to simulate the in vivo degradation of PG, released EGCG from the PG matrix over time. The released EGCG maintained its antioxidant capacity during incubation. These results indicate that thermally prepared PG matrices can be utilized as a promising EGCG carrier in the fields of tissue engineering and regenerative medicine.

Review of Dohan Eherenfest et al. (2009) on "Classification of platelet concentrates: From pure platelet-rich plasma (P-PRP) to leucocyte- and platelet-rich fibrin (L-PRF)"

This classic discusses the original publication of Dohan Eherenfest et al. on "Classification of platelet concentrates: from pure platelet-rich plasma (P-PRP) to leucocyte- and platelet-rich fibrin (L-PRF)", in which the authors propose four categories of platelet concentrates depending on their leucocyte and fibrin content (P-PRP, leucocyte- and platelet-rich plasma (L-PRP), pure platelet-rich fibrin (P-PRF), and L-PRF) to group a "jungle" of products in which the term platelet-rich plasma (PRP) was used indistinctly. They were able to identify common factors such as: (1) the use of anticoagulants and immediate centrifugation of the blood after its collection; (2) most preparation techniques allowed platelet concentrate preparation within an hour; (3) the centrifugation aimed to separate the blood in layers that would allow the extraction of specific fractions; and (4) the product was activated with thrombin or calcium chloride. The reviewed manuscript has been listed among the most cited PRP articles in regenerative medicine, with more than 800 citations, driving current scientific research and clinical practise by categorising L-PRP and P-PRP (now, leucocyte-poor PRP). The classification has also opened the door to understanding intrinsic biological mechanisms between platelets, leukocytes, fibrin, and growth factors, which will later be considered for studying the proliferation and differentiation of cells in different tissues affected by PRP. Since the initial classification of platelet concentrates, several other classification systems have been proposed and published in the current literature such as platelet, activation, white blood cell (PAW), Mishra, platelet, leucocyte, red blood cells, and activation (PLRA), dose of platelet, efficiency, purity, and activation (DEPA), method, activation, red blood cells, spin, platelets, image guidance, leukocytes, and light activation (MARSPILL), etc. These classifications have identified important aspects of PRP that affect the biological composition and, ultimately, the indications and outcomes. To date, there is still a lack of standardisation in sample preparation, cohort heterogeneity, and incomplete reporting of sample preparation utilised, leading to a lack of clarity and challenging researchers and clinicians.

Characterization of the molecular composition and in vitro regenerative capacity of platelet-based bioproducts and related subfractions

The use and demand of platelet-based bioproducts in regenerative medicine is steadily increasing. However, it is very difficult to establish the real clinical benefits of these therapies, as the lack of characterization and detailed production methods of platelet-based bioproducts persists in the literature and precludes cross-study comparisons. We characterized the molecular composition and in vitro regenerative capacity of platelet-rich plasma (PRP) produced in a closed-system. Furthermore, we performed a parallel characterization on different PRP subfractions (plasma and plasma-free platelet lysate), identifying that the fractions containing platelet-derived cargo exert the most potent regenerative capacity. This observation led us to develop a method to obtain a platelet secretome highly enriched in growth factors, free of plasma and cellular components (PCT/IB2022/057936), with the aim of establishing a superior bioproduct. The molecular characterization of secretomes revealed agonist-dependent differences, which correlates with beneficial grades of regenerative capacity. Importantly, secretomes showed general superiority to PRP in vitro. We discuss the variables influencing the bioproduct quality (inter-donor variation, platelet source and processing methods). Finally, we propose that the characteristics of secretomes circumvents certain limitations of PRP (autologous vs allogeneic), and envision that optimizing post-processing protocols (nanoencapsulation, lyophilization), would allow their clinical application even beyond regenerative medicine. STATEMENT OF SIGNIFICANCE: The use and demand of platelet-based bioproducts in regenerative medicine is steadily increasing. However, it is very difficult to establish the real clinical benefits of these therapies, or to improve/personalize them, as the lack of characterization of the bioproducts and their production methods is a constant in the literature, reason that precludes cross-study comparisons. In the present manuscript, we provide a comprehensive molecular and functional characterization of platelet-based bioproducts and subfractions, including platelet rich plasma, plasma fractions and platelet secretomes produced with a methodology developed by our group. Our results show that the molecular composition of each fraction correlates with its regenerative capacity in vitro. Thus, a rigorous characterization of platelet-derived bioproducts will potentially allow universal use, customizing and new applications.

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.

Slow-sculpting graphene oxide/alginate gel loaded with platelet-rich plasma to promote wound healing in rats

Wounds, especially chronic wounds, have become an important problem that endangers human health. At present, there are many repair methods, and among them combines materials science and biology is one of the important repair methods. This study explored the preparation method, physicochemical properties, biological activity and safety of Platelet-Rich plasma (PRP)-loaded slow-sculpting graphene oxide (GO)/alginate gel, and applied it to acute full-thickness skin defect wounds in rats to observe its role in wound healing. The results show that the slow-sculpting GO/alginate gel has excellent plasticity and is suitable for a variety of irregularly shaped wounds. At the same time, its porous structure and water content can maintain the activity of platelets and their released growth factors in PRP, thereby promoting wound collagen synthesis and angiogenesis to accelerate wound healing. This indicates that the slow-sculpting GO/alginate gel is an excellent loading material for PRP, and the combination of the two may become one of the methods to promote wound repair.

The Physiological Inorganic Polymers Biosilica and Polyphosphate as Key Drivers for Biomedical Materials in Regenerative Nanomedicine

There is a need for novel nanomaterials with properties not yet exploited in regenerative nanomedicine. Based on lessons learned from the oldest metazoan phylum, sponges, it has been recognized that two previously ignored or insufficiently recognized principles play an essential role in tissue regeneration, including biomineral formation/repair and wound healing. Firstly, the dependence on enzymes as a driving force and secondly, the availability of metabolic energy. The discovery of enzymatic synthesis and regenerative activity of amorphous biosilica that builds the mineral skeleton of siliceous sponges formed the basis for the development of successful strategies for the treatment of osteochondral impairments in humans. In addition, the elucidation of the functional significance of a second regeneratively active inorganic material, namely inorganic polyphosphate (polyP) and its amorphous nanoparticles, present from sponges to humans, has pushed forward the development of innovative materials for both soft (skin, cartilage) and hard tissue (bone) repair. This energy-rich molecule exhibits a property not shown by any other biopolymer: the delivery of metabolic energy, even extracellularly, necessary for the ATP-dependent tissue regeneration. This review summarizes the latest developments in nanobiomaterials based on these two evolutionarily old, regeneratively active materials, amorphous silica and amorphous polyP, highlighting their specific, partly unique properties and mode of action, and discussing their possible applications in human therapy. The results of initial proof-of-concept studies on patients demonstrating complete healing of chronic wounds are outlined.

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

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

Clinical Application of Platelet Concentrates in Bovine Practice: A Systematic Review

Platelet concentrates (PCs) have become widely used in veterinary and human medicine. The PCs consist mainly of supraphysiological concentrations of platelets and, therefore, growth factors (GFs) which are stored within platelet α-granules. Among PCs, Platelet-Rich Plasma (PRP) is characterised by low-density fibrin. Research on the effect of PCs in cattle has surged in recent years; in particular, evidence has shown the positive use of PRP for treating reproductive problems, in vitro production of bovine embryos, sole ulcers and udder diseases. The aim of this report is to critically review, in accordance with the PRISMA guidelines, the available literature reporting clinical application in the bovine practice of PRP. Three bibliographic databases PubMed, Web of Science and Scopus were used for a broad search of "platelet concentrates" OR "PRP" OR "platelet-rich plasma" OR "PRF" OR "platelet-rich fibrin" AND "cows" OR "cattle". From 1196 papers, only six met the inclusion criteria. Two papers described the use of PRP in mastitis, two papers in uterine dysfunction and two papers in ovarian dysfunction. PRP offered a low-cost, easily obtained therapeutic option and showed positive results for these patients. However, given the different pathologies and definitions involved, further studies are necessary to assess its full clinical potential.

Research and publication trends on knee osteoarthritis and cellular senescence: a bibliometric analysis

Background: Cellular senescence is associated with age-related pathological changes, senescent cells promote the development of knee osteoarthritis. A better understanding between knee osteoarthritis and cellular senescence may enhance the effectiveness of therapies that aim to slow or stop the progression of this disease. Purpose: This study aimed to systematically analyze and visualize the publication trends, research frontiers and current research hotspots of knee osteoarthritis and cellular senescence by using bibliometrics. Methods: The publication search was performed on the Web of Science Core Collection database for documents published from 1992 to 2023. VOSviewer, Citespace, R package Bibliometrix and Microsoft Office Excel were used to study the characteristics of the publications. The publication number, countries, institutions, authors, journals, citations and co-citations, keywords were analyzed. Results: A total of 1,074 publications were analyzed, with an average annual growth rate of 29.89%. United States accounted for the biggest contributor, ranked first in publications and citations. Publications of this field were published in 420 journals, OSTEOARTHRITIS and CARTILAGE was the most influential. A total of 5,657 authors contributed to this research. The most productive author was Lotz, MK (n = 31, H-index = 22, Total citation = 2,619), followed by Loeser, R.F (n = 16, H-index = 14, Total citation = 2,825). However, the collaboration between authors was relatively weak. Out of the 1,556 institutions involved, 60% were from the United States. Scripps Research ranked first with 25 papers and a total of 2,538 citations. The hotspots of this field had focused on the pathomechanisms (e.g., expression, inflammation, apoptosis, autophagy, oxidative stress) and therapeutics (e.g., stem cell, platelet-rich plasma, transplantation, autologous chondrocytes, repair), and the exploration of Senolytics might be the important direction of future research. Conclusion: Research on the cross field of knee osteoarthritis and cellular senescence is flourishing. Age-related pathomechanism maps of various cells in the joint and the targeted medicines for the senescent cells may be the future trends. This bibliometric study provides a comprehensive analysis of this cross field and new insights into future research.

Clinical Applications of PRP: Musculoskeletal Applications, Current Practices and Update

Musculoskeletal tissues are often subjected to deleterious effects stemming from traumatic injuries or degenerative pathologies, which can impede the body's natural repair response. The advent of regenerative medicine has emerged as a promising therapeutic approach in modern patient care. Among the interventions in this cutting-edge field, platelet-rich plasma (PRP) and cell-based therapies, such as mesenchymal stem cells, have garnered significant attention. In this article, we endeavor to provide an overview of the current practices and recent developments in PRP therapy, with a particular emphasis on the clinical applications for musculoskeletal pathologies.

Expanding applications of allogeneic platelets, platelet lysates, and platelet extracellular vesicles in cell therapy, regenerative medicine, and targeted drug delivery

Platelets are small anucleated blood cells primarily known for their vital hemostatic role. Allogeneic platelet concentrates (PCs) collected from healthy donors are an essential cellular product transfused by hospitals to control or prevent bleeding in patients affected by thrombocytopenia or platelet dysfunctions. Platelets fulfill additional essential functions in innate and adaptive immunity and inflammation, as well as in wound-healing and tissue-repair mechanisms. Platelets contain mitochondria, lysosomes, dense granules, and alpha-granules, which collectively are a remarkable reservoir of multiple trophic factors, enzymes, and signaling molecules. In addition, platelets are prone to release in the blood circulation a unique set of extracellular vesicles (p-EVs), which carry a rich biomolecular cargo influential in cell-cell communications. The exceptional functional roles played by platelets and p-EVs explain the recent interest in exploring the use of allogeneic PCs as source material to develop new biotherapies that could address needs in cell therapy, regenerative medicine, and targeted drug delivery. Pooled human platelet lysates (HPLs) can be produced from allogeneic PCs that have reached their expiration date and are no longer suitable for transfusion but remain valuable source materials for other applications. These HPLs can substitute for fetal bovine serum as a clinical grade xeno-free supplement of growth media used in the in vitro expansion of human cells for transplantation purposes. The use of expired allogeneic platelet concentrates has opened the way for small-pool or large-pool allogeneic HPLs and HPL-derived p-EVs as biotherapy for ocular surface disorders, wound care and, potentially, neurodegenerative diseases, osteoarthritis, and others. Additionally, allogeneic platelets are now seen as a readily available source of cells and EVs that can be exploited for targeted drug delivery vehicles. This article aims to offer an in-depth update on emerging translational applications of allogeneic platelet biotherapies while also highlighting their advantages and limitations as a clinical modality in regenerative medicine and cell therapies.

Advances and prospects of platelet-rich plasma therapy in veterinary ophthalmology

In the recent decades, there has been a significant uptick on the use of platelet-rich plasma (PRP) as a better alternative for ophthalmologic therapies in pathologies, primarily of the ocular surface. PRP is a class of liquid platelet concentrate containing a supra-physiological concentration of platelets in a relatively small amount of plasma. Its potential to heal various tissues has piqued interest in its therapeutic application as a biomaterial in regenerative medicine. It is currently a popular therapeutic agent in plastic surgery, cardiothoracic surgery, reconstructive surgery, and even oral and maxillofacial surgery. Based on the data from in vitro and in vivo studies, it can be concluded that PRP possesses adequate therapeutic potential in ocular pathologies, especially those involving cornea. In addition, the high concentrations of growth factors (TGF-β, VEGF, EGF) present in the PRP accelerate the healing of the corneal epithelium. PRP has great therapeutic prospects in veterinary ophthalmology as a regenerative therapeutic modality. However, several variables are yet to be defined and standardized that can directly affect the efficacy of PRP application in different ophthalmic conditions. There is a shortage of research on the use of PRP in ocular surface defects compared to the number of studies and reports on the use of autologous and allogeneic serum eye drops. Therefore, a data-driven approach is required to generate consensus/guidelines for the preparation, characterization, and therapeutic use of PRP in veterinary ophthalmology. This review aims to inform readers of the latest research on PRP, including its preparation methods, physiological and biochemical properties, clinical applications in veterinary ophthalmology, and their safety and efficacy.

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.

Return to Sports and Functional Outcomes after Autologous Platelet-Rich Fibrin Matrix (PRFM) and Debridement in Midportion Achilles Tendinopathy: A Case Series with 24-Month Follow-Up

(1) Background: Achilles tendinopathy (AT) is characterized by load-induced tendon pain, stiffness, and functional impairment that may affect the tendon midportion or insertion. Platelet-rich fibrin matrix (PRFM) is a promising adjunctive therapy for AT. We analyzed 24-month pain and functional outcomes in a cohort of patients managed by tendon debridement and autologous PRFM application to determine whether the combined treatment ensured an early return to sports/work and satisfactory clinical outcomes and functional scores. (2) Methods: The 24-month outcomes of 32 sport-practicing patients with chronic midportion AT treated with debridement and autologous PRFM were evaluated in terms of time to return to sports/work. The AOFAS and VISA-A were computed preoperatively and at 6 and 24 months. Blazina scores were evaluated preoperatively and at 6 months; ankle range of motion was assessed at 1, 6, 12, 24 months; and patient satisfaction was assessed at 24 months. (3) Results: Altogether, all patients had resumed their sport(s) activity, at the same or higher level, after 25.41 days (±5.37). Regarding work, all patients were able to return to their jobs after 16.41 days (±2.43). Ankle dorsiflexion and plantarflexion increased significantly: the AOFAS rose from 54.56 (±6.47) to 97.06 (±4.06) and 98.88 (±2.21) at 6 and 12 months, respectively, and the mean VISA-A score rose from 69.16 (±7.35) preoperatively to 95.03 (±4.67) and 97.28 (±2.43) at 6 and 12 months, respectively, after treatment. There were no complications. Most (90.62%) patients were very satisfied. (4) Conclusions: In symptomatic midportion AT, surgical debridement and autologous PRFM ensured a fast return to sports/work (4 weeks), significantly improving AOFAS and VISA-A and Blazina scores already at 6 months and providing excellent clinical outcomes at 24 months.

The Efficacy of Platelet-Rich Plasma Injection Therapy in the Treatment of Patients with Achilles Tendinopathy: A Systematic Review and Meta-Analysis

BACKGROUND

Over the past few years, many studies have been conducted to evaluate the effectiveness of platelet-rich plasma (PRP) in treating musculoskeletal conditions. However, there is controversy about its benefits for patients with Achilles tendinopathy.

OBJECTIVE

This study aimed to investigate whether platelet-rich plasma injections can improve outcomes in patients with Achilles tendinopathy.

METHODS

A comprehensive literature search was conducted in PubMed, Embase, Cochrane Library, Web of Science, China Biomedical CD-ROM, and Chinese Science and Technology Journal databases to identify randomised controlled clinical trials that compared the efficacy of PRP injection in patients with Achilles tendinopathy (AT) versus placebo, published between 1 January 1966 and 1 December 2022. Review Manager 5.4.1 software was used for the statistical analysis, and the Jadad score was used to assess the included literature. Only 8 of the 288 articles found met the inclusion criteria.

RESULTS

Our work suggests that: The PRP treatment group had a slightly higher VISA-A score than the placebo group at 6 weeks [MD = 1.92, 95% CI (-0.54, 4.38), I² = 34%], at 12 weeks [MD = 0.20, 95% CI (-2.65 3.05), I² = 60%], and 24 weeks [MD = 2.75, 95% CI (-2.76, 8.26), I² = 87%]). However, the difference was not statistically significant. The Achilles tendon thickness was higher at 12 weeks of treatment in the PRP treatment group compared to the control group [MD = 0.34, 95% CI (-0.04, 0.71), p = 0.08], but the difference was not statistically significant. The VAS-improvement results showed no significant difference at 6 and 24 weeks between the two groups, respectively (MD = 6.75, 95% CI = (-6.12, 19.62), I² = 69%, p = 0.30), and (MD = 10.46, 95% CI = (-2.44 to 23.37), I² = 69%, p = 0.11). However, at 12 weeks of treatment, the PRP injection group showed a substantial VAS improvement compared to the control group (MD = 11.30, 95% CI = (7.33 to 15.27), I² = 0%, p < 0.00001). The difference was statistically significant. The return to exercise rate results showed a higher return to exercise rate in the PRP treatment group than the placebo group [RR = 1.11, 95% CI (0.87, 1.42), p = 0.40]; the difference was not statistically significant.

CONCLUSION

There is no proof that PRP injections can enhance patient functional and clinical outcomes for Achilles tendinopathy. Augmenting the frequency of PRP injections may boost the outcomes, and additionally, more rigorous designs and standardised clinical randomised controlled trials are needed to produce more reliable and accurate results.

Application of platelet-rich plasma in spinal surgery

With the aging of the population and changes in lifestyle, the incidence of spine-related diseases is increasing, which has become a major global public health problem; this results in a huge economic burden on the family and society. Spinal diseases and complications can lead to loss of motor, sensory, and autonomic functions. Therefore, it is necessary to identify effective treatment strategies. Currently, the treatment of spine-related diseases includes conservative, surgical, and minimally invasive interventional therapies. However, these treatment methods have several drawbacks such as drug tolerance and dependence, adjacent spondylosis, secondary surgery, infection, nerve injury, dural rupture, nonunion, and pseudoarthrosis. Further, it is more challenging to promote the regeneration of the interstitial disc and restore its biomechanical properties. Therefore, clinicians urgently need to identify methods that can limit disease progression or cure diseases at the etiological level. Platelet-rich plasma (PRP), a platelet-rich form of plasma extracted from venous blood, is a blood-derived product. Alpha granules contain a large number of cytokines, such as platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), epidermal growth factor, platelet factor 4 (PF-4), insulin-like growth factor-1 (IGF-1), and transforming growth factor-β (TGF-β). These growth factors allow stem cell proliferation and angiogenesis, promote bone regeneration, improve the local microenvironment, and enhance tissue regeneration capacity and functional recovery. This review describes the application of PRP in the treatment of spine-related diseases and discusses the clinical application of PRP in spinal surgery.

Platelet-rich plasma injection for acute Achilles tendon rupture : two-year follow-up of the PATH-2 randomized, placebo-controlled, superiority trial

Aims

To determine whether platelet-rich plasma (PRP) injection improves outcomes two years after acute Achilles tendon rupture.

Methods

A randomized multicentre two-arm parallel-group, participant- and assessor-blinded superiority trial was undertaken. Recruitment commenced on 28 July 2015 and two-year follow-up was completed in 21 October 2019. Participants were 230 adults aged 18 years and over, with acute Achilles tendon rupture managed with non-surgical treatment from 19 UK hospitals. Exclusions were insertion or musculotendinous junction injuries, major leg injury or deformity, diabetes, platelet or haematological disorder, medication with systemic corticosteroids, anticoagulation therapy treatment, and other contraindicating conditions. Participants were randomized via a central online system 1:1 to PRP or placebo injection. The main outcome measure was Achilles Tendon Rupture Score (ATRS) at two years via postal questionnaire. Other outcomes were pain, recovery goal attainment, and quality of life. Analysis was by intention-to-treat.

Results

A total of 230 participants were randomized, 114 to PRP and 116 to placebo. Two-year questionnaires were sent to 216 participants who completed a six-month questionnaire. Overall, 182/216 participants (84%) completed the two-year questionnaire. Participants were aged a mean of 46 years (SD 13.0) and 25% were female (57/230). The majority of participants received the allocated intervention (219/229, 96%). Mean ATRS scores at two years were 82.2 (SD 18.3) in the PRP group (n = 85) and 83.8 (SD 16.0) in the placebo group (n = 92). There was no evidence of a difference in the ATRS at two years (adjusted mean difference -0.752, 95% confidence interval -5.523 to 4.020; p = 0.757) or in other secondary outcomes, and there were no re-ruptures between 24 weeks and two years.

Conclusion

PRP injection did not improve patient-reported function or quality of life two years after acute Achilles tendon rupture compared with placebo. The evidence from this study indicates that PRP offers no patient benefit in the longer term for patients with acute Achilles tendon rupture.

Cite this article: Bone Joint J 2022;104-B(11):1256–1265.

The levels of TGFβ1, VEGF, PDGF-BB, and PF4 in platelet-rich plasma of professional soccer players: a cross-sectional pilot study

Background

Regenerative therapy using platelet-rich plasma (PRP), a rich source of growth factors, has become popular in orthopedic sports medicine. Elite athletes prefer PRP therapy for their injured muscles and tendons primarily to avoid the possible risks of surgical treatment. However, the clinical effectiveness of PRP therapy in elite athletes compared to that in non-athletes remains unknown. Therefore, to investigate the effectiveness of PRP therapy in professional athletes (pro-athletes), we focused on the quality of PRP preparations and compared the levels of bioactive molecules between pro-athletes and non-athletes.

Methods

PRP was prepared from healthy, non-smoking male professional soccer players (pro-athletes) (n = 22) and non-athletes (VEGF: n = 34, others: n = 38). The levels of TGFβ1, PDGF-BB, VEGF, and PF4 were determined using ELISA kits. Polyphosphate was probed with 4’,6-diamidino-2-phenylindole and monitored using a fluorometer. The body composition of the donors was determined using a bathroom weighing scale.

Results

The levels of TGFβ1 and VEGF were significantly lower in pro-athletes than in non-athletes, whereas PF4 levels were significantly higher in pro-athletes. No significant difference was found in PDGF-BB levels between these groups. Biomolecule levels were not correlated with polyphosphate levels.

Conclusion

TGFβ1, VEGF, and PDGF-BB levels in pro-athletes were not higher than those in non-athletes. These findings suggest that growth factor levels in PRP may not be a predominant determinant of the clinical effectiveness of PRP therapy in pro-athletes. Increased PF4 levels in pro-athletes suggest an immunological function of PRP that may positively influence tissue regeneration.

The Top 100 Most Cited Articles on Platelet-Rich Plasma Use in Regenerative Medicine-A Bibliometric Analysis-From the ESSKA Orthobiologic Initiative

Over the past few decades, more and more articles about platelet-rich plasma (PRP) use in regenerative medicine have been published. The aim of this study was to determine which articles have been most influential in this field by identifying and analyzing the characteristics of the 100 most cited articles. Articles on the use of PRP in regenerative medicine were identified via the Thomson ISI Web of Science database. A majority of the articles originated from the USA (36%). The top journal in terms of number of articles was American Journal of Sports Medicine (12%). Musculoskeletal system and orthopedics (54%) were the most popular fields of applications. Preclinical studies were the most represented study type, from which only 8 from 46 (17.4%) provided a complete numerical description of the injected product. Analysis showed a time-dependent trend of increasing quality of the clinical studies (p = 0.004), although none of them provided a complete biological characterization of the injected PRP. This study demonstrated that the use of PRP in regenerative medicine is a growing and popular area of research, mainly focused on orthopedic applications. Studies on PRP-derived exosomes, biological characterization, and correlation with clinical results might be areas of future trends.

Platelet Rich Plasma in the Repair of Articular Cartilage Injury: A Narrative Review

OBJECTIVE

This paper reviews the research of platelet-rich plasma (PRP) in articular cartilage injury repair, to assess the mechanism, utilization, and efficacy of PRP in the treatment of articular cartilage injury, hoping to provide a theoretical basis for the clinical application of PRP in the future.

MATERIALS AND METHODS

A comprehensive database search on PRP applications in cartilage repair was performed. Among them, the retrieval time range of PRP in clinical trials of repairing knee cartilage injury was from January 1, 2021 to January 1, 2022. Non-clinical trials and studies unrelated to cartilage injury were excluded.

RESULT

PRP can affect inflammation, angiogenesis, cartilage protection, and cellular proliferation and differentiation after articular cartilage injury through different pathways. In all, 13 clinical trials were included in the analysis.

CONCLUSION

PRP is an emergent therapeutic approach in tissue engineering. Most studies reported that PRP has a positive effect on cartilage injury, improving the joint function, meanwhile there is a lack of standardized standards. The technology of PRP in the repair and treatment of articular cartilage injury is worthy of further research.

In vitro evaluation of platelet extracellular vesicles (PEVs) for corneal endothelial regeneration

Corneal endothelial cells (CECs) slowly decrease in number with increasing age, which is a clinical issue as these cells have very limited regenerative ability. Therapeutic platelet biomaterials are increasingly used in regenerative medicine and cell therapy because of their safety, cost-effective manufacture, and global availability from collected platelet concentrates (PCs). Platelet extracellular vesicles (PEVs) are a complex mixture of potent bioactive vesicles rich in molecules believed to be instrumental in tissue repair and regeneration. In this study we investigated the feasibility of using a PEVs preparation as an innovative regenerative biotherapy for corneal endothelial dysfunction. The PEVs were isolated from clinical-grade human PC supernatants by 20,000 × g ultracentrifugation and resuspension. PEVs exhibited a regular, fairly rounded shape, with an average size of <200 nm and were present at a concentration of approximately 10¹¹ /mL. PEVs expressed cluster of differentiation 41 (CD41) and CD61, characteristic platelets membrane markers, and CD9 and CD63. ELISA and LC-MS/MS proteomic analyses revealed that the PEVs contained mixtures of growth factors and multiple other trophic factors, as well as proteins related to extracellular exosomes with functional activities associated with cell cadherin and adherens pathways. CECs treated with PEVs showed increased viability, an enhanced wound-healing rate, stronger proliferation markers, and an improved adhesion rate. PEVs did not exert cellular toxicity as evidenced by the maintenance of cellular morphology and preservation of corneal endothelial proteins. These findings clearly support further investigations of PEV biomaterials in animal models for translation as a new CEC regeneration biotherapy.

Borrowing the Features of Biopolymers for Emerging Wound Healing Dressings: A Review

Wound dressing design is a dynamic and rapidly growing field of the medical wound-care market worldwide. Advances in technology have resulted in the development of a wide range of wound dressings that treat different types of wounds by targeting the four phases of healing. The ideal wound dressing should perform rapid healing; preserve the body’s water content; be oxygen permeable, non-adherent on the wound and hypoallergenic; and provide a barrier against external contaminants—at a reasonable cost and with minimal inconvenience to the patient. Therefore, choosing the best dressing should be based on what the wound needs and what the dressing does to achieve complete regeneration and restoration of the skin’s structure and function. Biopolymers, such as alginate (ALG), chitosan (Cs), collagen (Col), hyaluronic acid (HA) and silk fibroin (SF), are extensively used in wound management due to their biocompatibility, biodegradability and similarity to macromolecules recognized by the human body. However, most of the formulations based on biopolymers still show various issues; thus, strategies to combine them with molecular biology approaches represent the future of wound healing. Therefore, this article provides an overview of biopolymers’ roles in wound physiology as a perspective on the development of a new generation of enhanced, naturally inspired, smart wound dressings based on blood products, stem cells and growth factors.

Platelet-Rich Plasma as an Orthobiologic: Clinically Relevant Considerations

Platelet-rich plasma (PRP) is an autologous blood-derived product processed to concentrate platelets and the associated growth factors. PRP has been shown to be relatively well-tolerated and safe to use for a number of conditions in humans, equines, and canines. There are multiple commercial systems that have been validated for canine use. These systems use a variety of methodologies to produce a PRP product. However, PRP products have been shown to differ greatly between systems. Further study is needed to fully elucidate optimal component concentrations for various indications.

Clinical Response After Treatment of Knee Osteoarthritis With a Standardized, Closed-System, Low-Cost Platelet-Rich Plasma Product: 1-Year Outcomes

Background:

Intra-articular infiltration of platelet-rich plasma (PRP) is an alternative therapeutic option to classic hyaluronic acid for the treatment of symptomatic knee osteoarthritis (KOA). However, variation in preparation methods and quality assessment of PRP makes the study of its real clinical efficacy difficult.

Purpose:

To (1) evaluate the clinical efficacy of a characterized PRP product prepared in a standardized manner and in a closed-system for the treatment of KOA and to (2) evaluate the association of the clinical response to PRP-related variables.

Study Design:

Case series; Level of evidence, 4.

Methods:

We recruited 130 patients with nonoperative KOA and evaluated them for 1 year. PRP was prepared from a donation of autologous blood, obtaining 3 aliquots of approximately 10mL of product, which were frozen, allowing platelet disruption, platelet factor release, and long-term storage, until administration. Patients were treated 3 consecutive times every 4 weeks with an intra-articular PRP knee injection under sterile conditions. Complete blood count was performed on the whole-blood sample and the processed PRP before freezing it, for product quality assessment. Patients were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and basic satisfaction scale at 3 months, 6 months, and 1 year after intervention.

Results:

Quality assessment confirmed a leukocyte-poor PRP product (white blood cell count, 0.09 ± 0.09 × 10⁹/L) with a high platelet purity (platelet count, 630.86 ± 191.75 × 10⁹/L). WOMAC scores improved, and basic satisfaction was achieved in 70% of patients. No adverse events were reported. No correlations were observed between PRP quality parameters and clinical results. PRP complete treatment production costs were €108/US$125 (€36/US$41.6 per injection).

Conclusion:

This standardized PRP production method resulted in improved WOMAC scores at 1 year postoperatively in 70% of patients with KOA. This technique was safe and affordable and ensured consecutive infiltrations with the same product to each patient.

Effectiveness of intradiscal platelet rich plasma for discogenic low back pain without Modic changes: A randomized controlled trial

Objective

To determine if autologous platelet-rich plasma (PRP) injection into a degenerative intervertebral disc, without Modic changes on magnetic resonance imaging (MRI), improve pain and function.

Design

Prospective, randomized controlled study.

Setting

Outpatient spine practice (Stichting Rugpoli, Netherlands).

Participants

Adults with chronic low back pain referred to Stichting Rugpoli, according to the Dutch General Practitioners Guidelines, unresponsive to conservative treatment, without Modic changes on MRI.

Methods

Provocation discography was performed to confirm the suspected disc was the source of pain. Participants were randomized to receive 1.0 ​cc intradiscal PRP (intervention) or 1.0 ​cc Saline with 0.2g Kefzol (control). Data on pain (Numeric Rating Scale), physical function (Roland Morris Disabilty Questionnaire, RMDQ), and participants' general perceived health (SF-12) were collected at 1 week, 4 weeks, 2 months, 6 months, 9 months and 1 year. A repeated-measures analysis (mixed model) was used for comparing the outcomes of the groups.

Results

Of the initial 98 (49 intervention, 49 control) patients randomized, 89 (91%) (44 intervention, 45 control) with complete outcome data were analyzed. Groups were balanced at baseline. After twelve months no differences between groups were found in the average pain (improved 21/44 in intervention vs 16/45 in control, p ​= ​0.244), the disability scores (RMDQ minimal 3 points improvement 22/44 in intervention vs 24/45 in control, p ​= ​0.753) and the SF-12 (mean difference physical health -1.19, 95% CI -5.39 to 2.99, p ​= ​0.721, and mental health -0.34, 95% CI -3.99 to 3.29, p ​= ​0.834). One serious adverse event occurred (spondylodiscitis) after intervention.

Conclusion

Participants who received intradiscal PRP showed no significant improvement in pain or functionality compared to the control group at 1 year follow up.

Synergy of Human Platelet-Derived Extracellular Vesicles with Secretome Proteins Promotes Regenerative Functions

Platelet-rich plasma is a promising regenerative therapeutic with controversial efficacy. We and others have previously demonstrated regenerative functions of human platelet lysate (HPL) as an alternative platelet-derived product. Here we separated extracellular vesicles (EVs) from soluble factors of HPL to understand the mode of action during skin-organoid formation and immune modulation as model systems for tissue regeneration. HPL-EVs were isolated by tangential-flow filtration (TFF) and further purified by size-exclusion chromatography (SEC) separating EVs from (lipo)protein-enriched soluble fractions. We characterized samples by tunable resistive pulse sensing, western blot, tandem mass-tag proteomics and super-resolution microscopy. We evaluated EV function during angiogenesis, wound healing, organoid formation and immune modulation. We characterized EV enrichment by TFF and SEC according to MISEV2018 guidelines. Proteomics showed three major clusters of protein composition separating TSEC-EVs from HPL clustering with TFF soluble fractions and TFF-EVs clustering with TSEC soluble fractions, respectively. HPL-derived TFF-EVs promoted skin-organoid formation and inhibited T-cell proliferation more efficiently than TSEC-EVs or TSEC-soluble fractions. Recombining TSEC-EVs with TSEC soluble fractions re-capitulated TFF-EV effects. Zeta potential and super-resolution imaging further evidenced protein corona formation on TFF-EVs. Corona depletion on SEC-EVs could be artificially reconstituted by TSEC late fraction add-back. In contrast to synthetic nanoparticles, which commonly experience reduced function after corona formation, the corona-bearing EVs displayed improved functionality. We conclude that permissive isolation technology, such as TFF, and better understanding of the mechanism of EV corona function are required to realize the complete potential of platelet-based regenerative therapies.