Autologous fibrin matrices: A potential source of biological mediators that modulate tendon cell activities

Exploring the applications of platelet-rich plasma in tissue engineering and regenerative medicine: evidence from goat and sheep experimental research

Platelet-rich plasma (PRP) has emerged as a promising therapeutic approach in regenerative medicine. It contains various growth factors and bioactive molecules that play pivotal roles in tissue repair, regeneration, and inflammation modulation. This comprehensive narrative review delves into the therapeutic potential of PRP in experimental goat and sheep research, exploring recent advancements, challenges, and future prospects in the field. PRP has been explored for its application in musculoskeletal injuries, wound healing, and orthopedic conditions. Studies have demonstrated the ability of PRP to accelerate tissue healing, reduce inflammation, and improve the overall quality of healing. Recent advancements in PRP technology have led to the development of novel formulations and delivery methods to enhance its therapeutic efficacy. PRP has shown promise in tendon and ligament injuries, osteoarthritis, and bone fractures in experimental goat and sheep research. Despite these advancements, several challenges and opportunities exist to harness the full therapeutic potential of PRP in regenerative medicine. Standardizing PRP preparation protocols, including blood collection techniques, centrifugation parameters, and activation methods, is essential to ensure consistency and reproducibility of the findings. Moreover, further research is needed to elucidate the optimal dosing, frequency, and timing of PRP administration for different clinical indications. Research conducted in goat and sheep models provides evidence supporting the translational potential of PRP in tissue engineering and regenerative medicine. By harnessing the regenerative properties of PRP and leveraging insights from preclinical studies, researchers can develop innovative therapeutic strategies to address unmet clinical needs and improve patient outcomes in diverse medical specialties.

Current Challenges in the Development of Platelet-Rich Plasma-Based Therapies

Nowadays, biological therapies are booming and more of these formulations are coming to the market. Platelet-rich plasma, or PRP, is one of the most widely used biological therapies due to its ease of obtention and autologous character. Most of the techniques to obtain PRP are focusing on new processes and methods of optimization. However, not enough consideration is being given to modify the molecular components of PRP to generate more effective formulations with the aim of improving PRP treatments. Therefore, this review covers different novel PRP-obtaining methods that attempt to modify the molecular composition of the plasma.

The Biological Effect of Platelet-Rich Plasma on Rotator Cuff Tears: A Prospective Randomized In Vivo Study

The positive effect of platelet-rich plasma (PRP) on tendon metabolism has been extensively investigated and proven in vitro. Additionally, in vivo animal studies have correlated the application of PRP with the enhancement of tenocyte anabolic activity in the setting of tendon degeneration. However, less is known about its in vivo effect on human tendon biology. The purpose of the current prospective randomized comparative study was to evaluate the effect of PRP on torn human supraspinatus tendon. Twenty consecutive eligible patients with painful and magnetic resonance imaging (MRI)-confirmed degenerative supraspinatus tendon tears were randomized in a one-to-one ratio into two groups. The patients in the experimental group (n = 10) underwent an ultrasound-guided autologous PRP injection in the subacromial space 6 weeks before the scheduled operation. In the control group (n = 10), no injection was made prior to surgery. Supraspinatus tendon specimens were harvested from the lateral end of the torn tendon during shoulder arthroscopy and were evaluated under optical and electron microscopy. In the control group, a mixed cell population of oval and rounded tenocytes within disorganized collagen and sites of accumulated inflammatory cells was detected. In contrast, the experimental group yielded abundant oval-shaped cells with multiple cytoplasmic processes within mainly parallel collagen fibers and less marked inflammation, simulating the intact tendon structure. These findings indicate that PRP can induce microscopic changes in the ruptured tendon by stimulating the healing process and can facilitate a more effective recovery.

Immunohistochemical Analysis of Knee Chondral Defect Repair after Autologous Particulated Cartilage and Platelet-Rich Plasma Treatment in Sheep

This study performs an analysis that will enable the evaluation of the quality, durability, and structure of repaired cartilaginous extracellular matrix tissue using an autologous-based particulated autograft cartilage and platelet-rich plasma treatment (PACI + PRP). A single-blind controlled experiment was conducted on 28 sheep to evaluate the efficacy of the PACI + PRP treatment for cartilage defects. Full-thickness 8 mm diameter defects were created in the weight-bearing area of both knees. The right knees received PACI + PRP. The left knees were treated with Ringer's lactate solution (RLS) or hyaluronic acid (HA) injections. Sheep were euthanized at 9- or 18-months post-surgery. An extensive immunohistochemical analysis was performed to assess collagen types (I, II, III, V, VI, IX, X, XI) and aggrecan positivity. A semiquantitative scoring system provided a detailed evaluation of immunostaining. Collagens and aggrecan scores in the PACI + PRP groups were similar to healthy cartilage. Significant differences were found in collagens associated with matrix maturity (II and V), degradation (IX), structure and mechanics (VI), and hypertrophy (X) between healthy cartilage and RLS- or HA-repaired cartilage. The PACI + PRP treatment advanced the repair cartilage process in chondral defects with mature hyaline cartilage and enhanced the structural and mechanical qualities with better consistent cartilage, less susceptible to degradation and without hypertrophic formation over time.

Global research trends on platelet-rich plasma for tendon and ligament injuries from the past two decades: A bibliometric and visualized study

Background

In sports medicine, tendon and ligament injuries are the most prevalent conditions, and with the booming of sports competition, the incidence of sports injuries is gradually increasing, investigating more potent therapeutic options is therefore becoming increasingly crucial. Platelet-rich plasma therapy has gained popularity as an effective and secure treatment in recent years. Currently, a faceted systematic and clear visual analysis is lacking in this research area.

Methods

The literature related to using platelet-rich plasma to treat ligament and tendon injuries from 2003 to 2022 in the core dataset of the Web of Science database was collected and analyzed visually using Citespace 6.1 software. Research hotspots and development trends were analyzed in terms of high-impact countries or regions, authors, research institutions, keywords, and cited literature.

Results

The literature comprised a total of 1,827 articles. The annual publication volume of relevant literature has demonstrated a significant development tendency as the field of platelet-rich plasma research for tendon and ligament injuries has heated up in recent years. With 678 papers, the United States came in top place, followed by China with 187 papers. Hosp Special Surg ranked first with 56 papers. The hot research topics analyzed by keywords were tennis elbow, anterior cruciate ligament, rotator cuff repair, achilles tendon, mesenchymal stem cells, guided tissue regeneration, network meta analysis, chronic patellar tendinopathy, and follow up.

Conclusion

Analysis of the research literature over the past 20 years shows that the United States and China will continue to dominate in terms of volume of publications based on annual volume and trends, with some collaboration among high-impact authors and further collaboration still needed in different countries and institutions. Platelet-rich plasma is widely used in the treatment of tendon ligament injuries. Its clinical efficacy is influenced by a number of factors, the main ones being the inconsistency in the preparation and composition of platelet-rich plasma and its related preparations, and the differences in efficacy due to different activation methods of platelet-rich plasma, as well as factors such as injection time, injection site, administration method, number of administrations, acidity and evaluation methods, In addition, the applicability to different injury diseases remains controversial. In recent years, the molecular biology of platelet-rich plasma for tendon ligament therapy has received increasing attention.

Molecular and Biologic Effects of Platelet-Rich Plasma (PRP) in Ligament and Tendon Healing and Regeneration: A Systematic Review

Platelet-rich plasma (PRP) has been introduced and applied to a wide spectrum of acute and chronic ligament and tendon pathologic conditions. Although the biological effect of PRP has been studied thoroughly in both animal and human studies, there is no consensus so far on the exact mechanism of its action as well as the optimal timing and dosage of its application. Therefore, we conducted a systematic review aiming to evaluate the molecular effect of the administration of PRP in tendoligamentous injuries and degenerative diseases. The literature search revealed 36 in vitro and in vivo studies examining the healing and remodeling response of animal and human ligament or tendon tissues to PRP. Platelet-rich plasma added in the culture media was highly associated with increased cell proliferation, migration, viability and total collagen production of both ligament- and tendon-derived cells in in vitro studies, which was further confirmed by the upregulation of collagen gene expression. In vivo studies correlated the PRP with higher fibroblastic anabolic activity, including increased cellularity, collagen production and vascularity of ligament tissue. Similarly, greater metabolic response of tenocytes along with the acceleration of the healing process in the setting of a tendon tear were noticed after PRP application, particularly between the third and fourth week after treatment. However, some studies demonstrated that PRP had no or even negative effect on tendon and ligament regeneration. This controversy is mainly related to the variable processes and methodologies of preparation of PRP, necessitating standardized protocols for both investigation and ap-plication.

Transosseous-Equivalent/Suture Bridge Technique in Combination With Platelet-Rich Plasma Application Yield Optimal Clinical Outcomes in Arthroscopic Rotator Cuff Repair: A Bayesian Network Analysis of Randomized Controlled Trials

PURPOSE

To assess the clinical evidence defining the optimal combination of arthroscopic suture technique and platelet-rich products (PRP), and application for arthroscopic rotator cuff repair (ARCR).

METHODS

All level of evidence (LOE) I randomized controlled trials (RCT) focusing on arthroscopic suture technique and/or PRP application in ARCR were included. The exclusion criteria were LOE II or worse, studies with other interventions, studies reported none of the predetermined clinical outcomes; studies unable to extract any precise data; studies from the same patient group of included studies. A pair-wise meta-analysis and Bayesian network analysis were performed on each comparison. The intervention options were ranked by Bayesian network analysis.

RESULTS

27 studies comprising 1,947 individuals met the inclusion criteria. The application of transosseous equivalent/suture bridge repair (SB) with PRP (SB+PRP) significantly reduced retear rate (risk ratio [RR], 0.29; 95% confidence interval [CI], [0.15, 0.55].) and increased Constant-Murley score (mean difference, 1.90; 95% CI, [0.14, 3.74]), compared to SB repair. Single-row repair (SR) with PRP usage (SR+PRP) significantly reduced retear rate (RR, 0.27; 95% CI, [0.12, 0.55]) and pain visual analog scale (VAS) (mean difference: -0.84; 95% CI [-1.39, -0.46].), increased University of California, Los Angeles (UCLA) shoulder score (mean difference: 1.48; 95% CI [0.50, 2.58]) and Constant-Murley score (mean difference: 4.53; 95% CI [2.65, 6.38]), compared to SR repair. The ranking for outcomes demonstrated SB+PRP resulted in the best retear rate, UCLA shoulder score, with the second-best postoperative pain, Constant-Murley score, while SR+PRP resulted in the best postoperative pain, Constant-Murley score, with the second-best retear rate and UCLA score.

CONCLUSION

Arthroscopic rotator cuff repair utilizing SB+PRP yields optimal retear rate and UCLA shoulder score, with the second-best postoperative pain and Constant-Murley shoulder outcome score, while SR+PRP yields the best in these two parameters.

LEVEL OF EVIDENCE

Level I, Bayesian network analysis of level I RCT.

Particulate cartilage and platelet-rich plasma treatment for knee chondral defects in sheep

PURPOSE

Articular cartilage is vulnerable to multiple types of damage and it has limited reparative and regenerative capacities due to its absence of vascularity. Although a large number of therapeutic strategies exist to treat chondral defects, they have some limitations, such as fibrocartilage formation. Therefore, the goal of the present study was to evaluate the chondrogenic regenerative properties of an autologous-made matrix of particulated cartilage and platelet-rich plasma (PACI + PRP) implantation for the treatment of full-thickness chondral defects in sheep.

METHODS

A full-thickness 8 mm diameter cartilage defect was created in the weight-bearing area of the medial femoral condyle in both knees of 16 sheep. The right knees of all animals were treated with particulated autograft cartilage implantation and platelet-rich plasma, while the left knees were injected with Ringer's lactate solution or hyaluronic acid. The sheep were killed 9 or 18 months after surgery. Macroscopic evaluations were performed using three different scoring systems, and histopathological evaluations were performed using a modified scoring system based on different scoring systems.

RESULTS

The PACI + PRP groups showed statistically significant differences in the percentage of defect repair and chondrocytes in the newly formed cartilage tissue at 18 months compared to 9 months.

CONCLUSIONS

The results suggest that macroscopic appearance, histological structure and chondrocyte repair were improved when using PACI + PRP treatment for chondral defects, producing an outcome similar to the surrounding healthy cartilage. PACI + PRP is a totally autologous, easy, and unexpensive treatment that can be performed in one-step procedure and is useful as a therapeutic option for knee chondral defects.

Evolution and Clinical Advances of Platelet-Rich Fibrin in Musculoskeletal Regeneration

Over the past few decades, various forms of platelet concentrates have evolved with significant clinical utility. The newer generation products, including leukocyte-platelet-rich fibrin (L-PRF) and advanced platelet-rich fibrin (A-PRF), have shown superior biological properties in musculoskeletal regeneration than the first-generation concentrates, such as platelet-rich plasma (PRP) and plasma rich in growth factors. These newer platelet concentrates have a complete matrix of physiological fibrin that acts as a scaffold with a three-dimensional (3D) architecture. Further, it facilitates intercellular signaling and migration, thereby promoting angiogenic, chondrogenic, and osteogenic activities. A-PRF with higher leukocyte inclusion possesses antimicrobial activity than the first generations. Due to the presence of enormous amounts of growth factors and anti-inflammatory cytokines that are released, A-PRF has the potential to replicate the various physiological and immunological factors of wound healing. In addition, there are more neutrophils, monocytes, and macrophages, all of which secrete essential chemotactic molecules. As a result, both L-PRF and A-PRF are used in the management of musculoskeletal conditions, such as chondral injuries, tendinopathies, tissue regeneration, and other sports-related injuries. In addition to this, its applications have been expanded to include the fields of reconstructive cosmetic surgery, wound healing in diabetic patients, and maxillofacial surgeries.

Histological and biochemical evaluation of plasma rich in growth factors treatment for grade II muscle injuries in sheep

The purpose of this study was to perform a histological and biochemical evaluation of the influence of plasma rich in growth factors (PRGF) on muscle regeneration process after a surgically induced grade II muscle laceration. A randomized, single blind, controlled experimental research was conducted including twenty-one adult healthy sheep, randomly divided in three groups (n = 7). A grade II surgical section was performed in the biceps femoris muscle of both hindlimbs. After two days (basal time), intralesional infiltration of autologous PRGF or Saline solution was randomly administered in both hindlimbs. Treatment was repeated once a week. Animal groups were euthanized at 1 (T1), 2 (T2) or 4 (T4) weeks. Histological assessment showed that PRGF intralesional injection induced a significant decrease of inflammatory cells density, significant higher centrally nucleated fibers percentage and significantly smaller fibrotic areas compared to Saline-treated muscles at T1, T2 and T4. Also, lower vascular density, with lower capillaries cross-sectional area, in PRGF group compared to Saline was observed. Biochemical analysis revealed a significant higher expression level of MYOD1, MYF5 and MYOG genes in PRGF groups at T1 compared to Saline treated muscles. At ultrastructural level, PRGF groups presented scarce edema and loss of connective tissue structure, as well as higher mitochondrial density adequately associated to the sarcomere unit in contrast to the Saline group. In conclusion, histological, biochemical, and ultrastructural results showed that PRGF treatment improved muscle regeneration process leading to more mature histological aspect in newly formed muscle tissue after a surgically induced grade II muscle injury.

An Autologous Topical Serum Derived from Platelet-Rich Plasma Therapy for the Management of Sensitive Skin Alterations: A Case Series Report

Background

Although the underlying pathophysiology of sensitive skin remains unknown, it presents clinical symptoms like erythema, burning and dryness associated with other inflammatory dermatoses such as dermatitis or rosacea.

Objective

The aim of the present report was to provide preliminary data about the efficacy of Endoret-Serum (ES) as an autologous therapy for the topical management of sensitive skin alterations.

Materials and Methods

Five patients underwent a daily topical ES treatment that was maintained for three months. Clinical assessment was carried out using validated dermatological surveys (DLQI, IGA, Likert, PGI-I). Additionally, skin hydration measurement and high-resolution topographic and reflectance confocal imaging analysis were carried out.

Results

No adverse events were observed during the treatment. At the end of the follow-up period, surveys highlighted a significant therapeutic effect compared to baseline. Skin hydration was also improved, and topographic images showed a decrease in patient’s underlying inflammatory and vascular condition.

Conclusion

This preliminary report suggests that Endoret-Serum may be useful in the management of clinical symptoms derived from sensitive skin alterations.

Ultrasound-guided platelet-rich plasma injection for the treatment of recalcitrant rotator cuff disease in wheelchair users with spinal cord injury: A pilot study

Context/Objective: Wheelchair users with spinal cord injury (SCI) have a high risk of developing shoulder pain, caused by rotator cuff disease. Platelet-rich plasma (PRP) is a potential treatment after conservative treatments fail and prior to surgical intervention; however, it has not been tested in wheelchair users who have recalcitrant shoulder pain associated with rotator cuff disease. The objective of this pilot project was to test the safety and potential treatment effect of an ultrasound-guided PRP injection for shoulder pain in the aforementioned population.Design: Prospective, quasi-experimental.Setting: Clinical research center.Participants: Six wheelchair users with SCI (3 paraplegia, 3 tetraplegia) who had chronic shoulder pain due to rotator cuff disease (presence of anterior shoulder pain, positive physical examination tests for rotator cuff disease, and tendinopathy demonstrated by ultrasound) and failed at least six months of conservative treatment.Interventions: Ultrasound-guided PRP injection into pathological shoulder tendons, targeting the supraspinatus. Subjects were provided a standardized stretching and strengthening program and were followed for 4, 8, 12, and 24 weeks post-intervention with outcomes collected at each time-point.Outcome Measures: Wheelchair User's Shoulder Pain Index (WUSPI); pain Numerical Rating Scale (NRS); physical and ultrasound examinations for supraspinatus tendinopathy; 5-point patient global impression of change (PGIC).Results: WUSPI (69.9%, P < 0.001), NRS (49.6%, P < 0.01), and physical exam scores (35.7%, P < 0.01) decreased 24 weeks after treatment. Participants reported overall improvement in their status as a result of the treatment. No adverse events were noted, and no changes in ultrasound markers for tendinopathy were observed.Conclusion: A single, ultrasound-guided PRP injection into the supraspinatus tendon, followed by a stretching and strengthening exercise program, was safe and provided improvements in shoulder pain outcome measures in this sample for 24 weeks. Lack of blinding, short-term follow-up, and a suitable control group warrant a larger randomized controlled trial.Trial Registration: NCT01355549.

Healing through the lens of immunothrombosis: Biology-inspired, evolution-tailored, and human-engineered biomimetic therapies

Evolution, from invertebrates to mammals, has yielded and shaped immunoclotting as a defense and repair response against trauma and infection. This mosaic of immediate and local wound-sealing and pathogen-killing mechanisms results in survival, restoration of homeostasis, and tissue repair. In mammals, immunoclotting has been complemented with the neuroendocrine system, platelets, and contact system among other embellishments, adding layers of complexity through interconnecting blood-born proteolytic cascades, blood cells, and the neuroendocrine system. In doing so, immunothrombosis endows humans with survival advantages, but entails vulnerabilities in the current unprecedented and increasingly challenging environment. Immunothrombosis and tissue repair appear to go hand in hand with common mechanisms mediating both processes, a fact that is underlined by recent advances that are deciphering the mechanisms of the repair process and of the biochemical pathways that underpins coagulation, hemostasis and thrombosis. This review is intended to frame both the universal aspects of tissue repair and the therapeutic use of autologous fibrin matrix as a biology-as-a-drug approach in the context of the evolutionary changes in coagulation and hemostasis. In addition, we will try to shed some light on the molecular mechanisms underlying the use of the autologous fibrin matrix as a biology-inspired, evolution-tailored, and human-engineered biomimetic therapy.

Platelet-Rich Product Supplementation in Rotator Cuff Repair Reduces Retear Rates and Improves Clinical Outcomes: A Meta-analysis of Randomized Controlled Trials

PURPOSE

The purpose of this study was to conduct a comprehensive systematic review and meta-analysis to investigate the clinical and imaging outcomes of all 4 types of platelet-rich therapies (pure platelet-rich plasma [P-PRP], leukocyte and platelet-rich plasma, pure platelet-rich fibrin, and leukocyte and platelet-rich fibrin) in rotator cuff repairs.

METHODS

A systematic literature search was performed to identify rotator cuff tears comparing any of the 4 types of platelet-rich products (PRP) to a control in rotator cuff repair. Data extracted from the studies included retear rates diagnosed with imaging studies, as well as outcome scores such as Constant, American Shoulder and Elbow Surgeons (ASES), University of California Los Angeles (UCLA), Simple Shoulder Test (SST), and visual analog scale (VAS). Meta-analyses compared postoperative outcome scores and retear rates between the control and study groups.

RESULTS

Seventeen studies were included in the meta-analysis. When pooling data from all studies, retear rate for the treatment group was 19.3%, compared to 25.4% for the control group (odds ratio [OR] 0.59, P = .0037). When stratified based on PRP type, only P-PRP resulted in a significant reduction in retear rate (OR 0.26, P = .0005). Overall, treatment with PRP significantly improved Constant scores when compared to controls (mean difference [MD] 2.41, P =.0027), as well as VAS scores (MD -0.12, P = .0014), and SST scores (MD 0.41, P = .0126). There was no significant difference in ASES scores (MD 0.37, P = .7762) or UCLA scores (MD 0.76, P =0.2447) between treatment and controls when pooling data from all studies.

CONCLUSIONS

This analysis demonstrates significant reductions in retear rates when rotator cuff repair is augmented with PRP. P-PRP appears to be the most effective formulation, resulting in significantly improved retear rates and clinical outcome scores when compared with controls.

History of autologous platelet-rich plasma: A short review

Background

Platelet‐rich plasma (PRP) is a medical material with numerous applications. It produces particularly spectacular effects when applied in cosmetic dermatology.

Aim

To illustrate the origin of the treatment.

Conclusion

The therapy originates from transfusiology, where it is applied as a concentrate of platelets to treat trombocytopenia. PRP treatment is 70 years old and has an increasing number of applications. PRP holds particular promise for cosmetic dermatology.

In vitro and in vivo Effect of Platelet-Rich Plasma-Based Autologous Topical Serum on Cutaneous Wound Healing

INTRODUCTION

Skin injury and wound healing is an inevitable event during lifetime. However, several complications may hamper the regeneration of the cutaneous tissue and lead to a chronic profile that prolongs patient recovery. Platelet-rich plasma is rising as an effective and safe alternative to the management of wounds. However, this technology presents some limitations such as the need for repeated blood extractions and health-care interventions.

OBJECTIVE

The aim of this study was to assess the use of an endogenous and storable topical serum (ES) derived from plasma rich in growth factors promoting wound healing, and to obtain preliminary data regarding its clinical and experimental effect over ulcerated skin models and patient care.

METHODS

Human dermal fibroblast and 3D organotypic ulcerated skin models were used to assess ES over the main mechanisms of wound healing including cell migration, edge contraction, collagen synthesis, tissue damage, extracellular matrix remodeling, cell death, metabolic activity, and histomorphometry analysis. Additionally, 4 patients suffering from skin wounds were treated and clinically assessed.

RESULTS

ES promoted dermal fibroblast migration, wound edge contraction, and collagen synthesis. When topically applied, ES increased collagen and elastin deposition and reduced tissue damage. The interstitial edema, structural integrity, and cell activity were also maintained, and apoptotic levels were reduced. Patients suffering from hard-to-heal wounds of different etiologies were treated with ES, and the ulcers healed completely within few weeks with no reported adverse events.

CONCLUSION

This preliminary study suggests that ES might promote cutaneous wound healing and may be useful for accelerating the re-epithelization of skin ulcers.

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

Background

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

Main body of the abstract

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

Short conclusion

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

Platelet-Rich Plasma Applications for Achilles Tendon Repair: A Bridge between Biology and Surgery

Achilles tendon ruptures are very common tendon ruptures and their incidence is increasing in modern society, resulting in work incapacity and months off sport, which generate a need for accelerated and successful therapeutic repair strategy. Platelet-rich plasma (PRP) is emerging as adjuvant human blood-derived constructs to assist Achilles tendon rupture treatment. However, myriad PRP preparation methods in conjunction with poor standardization in the modalities of their applications impinge on the consistent effectiveness of clinical and structural outcomes regarding their therapeutic efficacy. The purpose of this review is to provide some light on the application of PRP for Achilles tendon ruptures. PRP has many characteristics that make it an attractive treatment. Elements such as the inclusion of leukocytes and erythrocytes within PRP, the absence of activation and activation ex vivo or in vivo, the modality of application, and the adjustment of PRP pH can influence the biology of the applied product and result in misleading therapeutic conclusions. The weakest points in demonstrating their consistent effectiveness are primarily the result of myriad PRP preparation methods and the poor standardization of modalities for their application. Selecting the right biological scaffold and applying it correctly to restitutio ad integrum of ruptured Achilles tendons remains a daunting and complex task.

Biologic therapies for foot and ankle injuries

Introduction: The use of orthobiologics as supplemental treatment for foot and ankle pathologies have increased in the past decades. They have been used to improve the healing of bone and soft tissue injuries. There have been several studies that examined the use of biologics for knee and hip pathologies but the foot and ankle construct has unique features that must be considered.Areas covered: The biologics for foot and ankle injuries that are covered in this review are platelet-rich plasma (PRP), stem cells, growth factors, hyaluronic acid, bone grafts, bone substitutes, and scaffolds. These modalities are used in the treatment of pathologies related to tendon and soft tissue as well as cartilage.Expert opinion: The utilization of biological adjuncts for improved repair and regeneration of ankle injuries represents a promising future in our efforts to address difficult clinical problems. The application of concentrated bone marrow and PRP each represents the most widely studied and commonly used injection therapies with early clinical studies demonstrating promising results, research is also being done using other potential therapies such as stem cells and growth factors; further investigation and outcome data are still needed.

Development of a Platelet Lysate-Based Printable, Transparent Biomaterial With Regenerative Potential for Epithelial Corneal Injuries

Purpose

To develop a human platelet lysate (hPL)–based bioink that is transparent and also encompasses the regenerative properties of hPL to facilitate wound healing.

Methods

The effect of different batches of hPLand fetal bovine serum (FBS) on corneal epithelial cell growth and scratch assay was first examined using Incucyte Zoom. Various combinations of human fibrinogen (concentration range from 0.2 to 5 mg/mL) and thrombin (concentration from 1 to 10 U/mL) were combined with hPL to generate nine types of potential bioink. Rheology, transparency, and cell compatibility of bioinks were assessed and compared. The final selected bioink was used in an ex vivo corneal model to examine its ability in re-epithelization.

Results

No significant difference was detected in cell proliferation and wound healing tests between different hPL batches at the same concentration. Scratch assay data showed that hPL had significantly higher effect on wound healing than FBS. Comparing across the nine bioinks, bioink 5 consisting of 10% hPL, 2 mg/mL fibrinogen, and 5 U/mL thrombin demonstrated all required mechanical and cellular properties and was able to regenerate the full-thickness epithelium ex vivo.

Conclusions

The results showed that a transparent and adhesive bioink can be generated by combining hPL, fibrinogen, and thrombin together. The bioink can be directly applied to a human cornea to promote corneal re-epithelization with huge potential applications in corneal injuries.

Translational Relevance

The developed transparent hPL-based ink with its adhesive and healing ability showed that it could be used as a new treatment option for corneal injuries.

Long-term stability of a novel platelet-rich plasma-based topical serum for cutaneous applications

BACKGROUND

Skin alterations are usually related to chronic diseases that demand sustained and long-term dosages; hence, it is pivotal that the stability of treatments is preserved. A novel storable and endogenous topical serum (ES) based on the patient's own blood has been recently developed.

AIMS

To investigate the long-term stability of the formulation and to provide preliminary data of its biologic potential.

METHODS

Samples from six donors were obtained and either used as fresh samples or cold-stored for 6 months. Physicochemical, rheological, and biological stability of the formulation was determined.

RESULTS

Endogenous topical serum maintained unaltered its organoleptic properties, viscosity, pH, spreadability index, and sterility. The growth factor content including TGFβ-I, EGF, PDGF-AB, HGF, and Ang-I showed no decrease. In contrast, ES showed lower levels of IGF-I once stored. Dermal fibroblasts showed no change in their proliferative activity.

CONCLUSION

Endogenous topical serum showed to maintain its physicochemical and biological properties after six months of storage. ES might reduce the frequency of blood extractions and would enable patients with chronic disorders to maintain a daily use of the product in a minimally invasive way.

Comparison on effects of platelet-rich plasma versus autologous conditioned serum on Achilles tendon healing in a rat model

OBJECTIVE

The aim of this study was to compare the effects of local administrations of platelet-rich plasma (PRP) with autologous conditioned serum (ACS) on Achilles tendon healing in a rat model.

METHODS

In this study, 40 male Sprague-Dawley rats, aged 12 months and weighing 350 to 400 g were used. The rats were divided into three groups (n=10 in each group): a control group and two treatment groups (PRP vs ACS). A standardized procedure was applied for the complete rupture and repair of the Achilles tendon in each group. The PRP group received one dose of PRP on the operative area, and ACS group received ACS at 24, 48, and 72 hours after the surgery. The control group received no injection. Animals were sacrificed 30 days after the operation, and tendon healing in each group was assessed histopathologically based on Bonar's semi-quantitative score and Movin's semi-quantitative grading scale. For the biomechanical analyses, unoperated Achilles tendons of all rats in the control and ACS groups were also harvested, and pulling tests were applied to the specimen to measure the longitudinal axis strength. The highest force value among the data obtained was defined as the maximum strength value (Fmax).

RESULTS

The mean Bonar's score was significantly lower in the PRP group (3.8±0.8) than in the ACS (4.8±0.45) and control groups (5.2±0.837) (p=0.0028). The mean Movin's score was significantly lower in the PRP group (7.80±1.49) than in the ACS (9.8±1) and control groups (11.2±2.4) (p=0.029). The ratio of type I collagen was significantly higher in the PRP group (60±6) than in the ACS (52±4.5) and control groups (42±9) (p=0.005). Biomechanical results obtained from operated sites were comparable in terms of Fmax among groups (PRP, 33.93±2.61; ACS, 35.24±3.26; control, 35.69±3.62) (p=0.674). Similarly, the results obtained from unoperated sites were comparable among groups (PRP, 47.71±1.21; ACS, 48.14±2; control, 49.14.69±1.88) (p=0.395).

CONCLUSION

In terms of histopathological results, PRP seems to be more effective than ACS for Achilles tendon healing in rats.

Does the Application of Platelet-Rich Fibrin in Anterior Cruciate Ligament Reconstruction Enhance Graft Healing and Maturation? A Comparative MRI Study of 44 Cases

Background:

Anterior cruciate ligament (ACL) reconstruction performed with growth factors and activated platelets has been suggested to accelerate tendon ligamentization, leading to earlier return to daily activities and sports.

Hypotheses:

Platelet-rich fibrin (PRF) will result in improved graft maturation and healing as evaluated by magnetic resonance imaging (MRI) in patients undergoing hamstring ACL reconstruction. Hemostatic and analgesic properties of PRF will lead to less postoperative blood loss and pain.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 44 patients with isolated ACL injuries who underwent arthroscopic all-inside anatomic single-bundle ACL reconstruction with semitendinosus tendon graft were enrolled. Group 1 included 23 patients who had PRF sprayed to the surface of the graft; group 2 included 21 patients for whom no PRF was used. Patients were discharged after 24 hours and examined for hemarthrosis that needed to be aspirated. MRI was performed at the fifth postoperative month. A blinded radiologist evaluated graft maturation according to its signal intensity and the presence of synovial fluid at the tunnel-graft interface.

Results:

PRF-treated grafts demonstrated lower MRI signal intensity and less fluid in the graft-tunnel interface as compared with controls for the entire length of the graft. The mean full-length MRI signal intensities were 9.19 versus 16.59 (P = .047) for groups 1 and 2, respectively. Subgroup analysis of the semitendinosus grafts demonstrated a signal intensity of 11.57 versus 23.98 (P = .044) for the proximal third, 9.53 versus 13.83 (P = .237) for the midbody, and 6.48 versus 11.98 (P = .087) for the distal third. Synovial fluid at the graft-tunnel interface was detected in 1 patient in group 1 (4.3%) and 3 patients in group 2 (14.3%; P < .001). Patients in group 1 had significantly less hemarthrosis that needed to be aspirated (P = .003), while postoperative analgesia requirements were similar in both groups (P = .08). No clinical benefit of PRF could be demonstrated in clinical outcomes.

Conclusion:

Application of PRF led to superior graft integration and maturation in the proximal third of the ACL graft. There was no significant difference in MRI signal intensity in the midbody or distal tibial graft. Application of PRF also resulted in significantly lower rates of postoperative hemarthrosis that needed to be aspirated.

Co-treatment of wounds in rabbit skin with equine platelet-rich plasma and a commercial ointment accelerates healing

Abstract Autologous platelet-rich plasma (PRP) is beneficial in the healing process of reconstructive surgeries, contributing to the stimulation of angiogenesis; however, heterologous plasma has been shown to be more effective. The objective of this study was to verify, by macro- and microscopic evaluation, whether PRP accelerates the healing process as compared to a commercial ointment containing gentamicin, sulfanilamide, sulfadiazine, urea, and vitamin A (study ointment). This study used 24 white New Zealand rabbits, aged 12 months, and each weighing approximately 3 kg. The animals were separated into 4 equal groups and underwent wound induction through skin removal in the thoracic (study wound) and lumbar (control wound) dorsal midline. Study wounds were co-treated with equine PRP and the study ointment. Control wounds were treated with only the study ointment. Group I underwent histological evaluation 3 days after the skin removal procedure, group II after 7 days, group III after 14 days, and group IV after 21 days. A skin fragment was collected from each animal for histological evaluation. The co-treatment with heterologous equine PRP and the study ointment accelerated the healing process in the surgically induced skin wounds, confirming the acceleratory effect of PRP on wound healing.

In vitro characterization and clinical use of platelet-rich plasma-derived Endoret-Gel as an autologous treatment for atrophic scars

BACKGROUND

Normal healing process becomes severely dysregulated in pathophysiological conditions such as inflammation, infection or underlaying diseases. These scenarios hamper the standard healing pattern and dermal fibrotic tissue develops.

OBJECTIVE

In the present study a novel three-dimensional formulation (Endoret-Gel) based on plasma rich in growth factors technology (Endoret-PRGF) has been assessed for atrophic scar management.

MATERIALS AND METHODS

Microstructure analysis, growth factor content, and projection capacity of both formulations (Endoret-Gel and Endoret-PRGF) was assessed. Additionally, a clinical evaluation of Endoret-Gel treatment was also performed in a case of an extense atrophic scar.

RESULTS

Endoret-Gel presented high molecular weight plasmatic proteins that formed solid thermal aggregates enclosed by a stable fibrin network. This formulation has a higher cutaneous projection capacity compared with Endoret-PRGF. Both formulations presented a high load of bioactive proteins such as EGF, PDGF-AB, and IGF-I being higher in liquid Endoret-PRGF. Clinical results evidenced that infiltrations of Endoret-Gel derived in an early volumetric disposal that was maintained for several months. The treatment provided and immediate soft tissue augmentation and scar amelioration effect that was translated into a noticeable clinical improvement of the injury. No side effects or adverse events were reported during ten-month follow-up period.

CONCLUSION

These preliminary findings suggest that Endoret-Gel may act not only as a temporary volumizer but also as soft tissue stimulator that might be used as a monotherapy for scar management.

Adipose-Derived Stromal Vascular Fraction Cells and Platelet-Rich Plasma: Basic and Clinical Implications for Tissue Engineering Therapies in Regenerative Surgery

Cell-based therapy and regenerative medicine offer a paradigm shift in regard to various diseases causing loss of substance or volume and tissue or organ damage. Recently, many authors have focused their attention on mesenchymal stem cells for their capacity to differentiate into many cell lineages. The most widely studied types are bone marrow mesenchymal stem cells and adipose derived stem cells (ADSCs), which display similar results. Based on the literature, we believe that the ADSCs offer advantages because of lower morbidity during the harvesting procedure. Additionally, platelet-rich plasma can be used in this field for its ability to stimulate tissue regeneration. The aim of this chapter is to describe ADSC preparation and isolation procedures, preparation of platelet-rich plasma, and the application of ADSCs in regenerative plastic surgery. We also discuss the mechanisms and future role of ADSCs in cell-based therapy and tissue engineering.

Platelet-Rich Fibrin Scaffolds for Cartilage and Tendon Regenerative Medicine: From Bench to Bedside

Nowadays, research in Tissue Engineering and Regenerative Medicine is focusing on the identification of instructive scaffolds to address the requirements of both clinicians and patients to achieve prompt and adequate healing in case of injury. Among biomaterials, hemocomponents, and in particular Platelet-rich Fibrin matrices, have aroused widespread interest, acting as delivery platforms for growth factors, cytokines and immune/stem-like cells for immunomodulation; their autologous origin and ready availability are also noteworthy aspects, as safety- and cost-related factors and practical aspects make it possible to shorten surgical interventions. In fact, several authors have focused on the use of Platelet-rich Fibrin in cartilage and tendon tissue engineering, reporting an increasing number of in vitro, pre-clinical and clinical studies. This narrative review attempts to compare the relevant advances in the field, with particular reference being made to the regenerative role of platelet-derived growth factors, as well as the main pre-clinical and clinical research on Platelet-rich Fibrin in chondrogenesis and tenogenesis, thereby providing a basis for critical revision of the topic.

Cartilage regeneration using a novel autologous growth factors-based matrix for full-thickness defects in sheep

PURPOSE

To investigate the chondrogenic-regenerative properties of a novel autologous-made matrix composed of hyaline cartilage chips combined with a growth factors-based clot for full-thickness defects in sheep.

METHODS

A full-thickness, 8-mm diameter cartilage defect was created in the weight-bearing area of the medial femoral condyle in 6 sheep. Treatment consisted of surgical implantation of an autologous-based matrix of hyaline cartilage chips combined with a clot of plasma poor in platelets and intraarticular injection of plasma rich in growth factors. Outcome measures at 1, 3 and 6 months included macroscopic International Cartilage Repair Society (ICRS) score, histological and immunohistochemical analysis for collagen expression, and transmission electron microscopy study.

RESULTS

The 6-month macroscopic evaluation showed nearly normal (11.1 ± 0.7) cartilage repair assessment. The ICRS score was significantly higher at 6 months compared to 3 months (5.5 ± 1.3; p < 0.0001) and 1 (1.1 ± 0.4; p < 0.0001) month. At 6 months, hyaline cartilage tissue filling the defect was observed with adequate integration of the regenerated cartilage at the surrounding healthy cartilage margin. At 6 months, mature chondrons and cartilage matrix contained collagen fibers with masked fibrillary structure, and the expression of collagen in the newly formed cartilage was similar in intensity and distribution pattern compared to the healthy adjacent cartilage.

CONCLUSIONS

This novel treatment enhanced chondrogenesis and regenerated hyaline cartilage at 6 months with nearly normal macroscopic ICRS assessment. Histological analysis showed equivalent structure to mature cartilage tissue in the defect and a collagen expression pattern in the newly formed cartilage similar to that found in adjacent healthy articular cartilage. The present technique may have clinical application for chondral injuries in humans because this procedure is cheap (no need for allograft, or expensive instrumentation/biomaterials/techniques), easy and fast-performing through a small arthrotomy, and safe (no rejection possibility because the patients' own tissue, cells, and plasma are used).

Synergistic activity of platelet rich plasma and high volume image guided injection for patellar tendinopathy

PURPOSE

Platelet rich plasma and high volume image guided injections of saline have been used in the treatment of patellar tendinopathy with positive results. As the different mechanisms of action do not interfere each other, it can be hypothesized that they can be used in combination. Aim of this study was twofold: first, to evaluate the efficacy of these two treatments in the management of patellar tendinopathy; second, to verify whether the combination of these therapies could provide further advantages.

METHODS

Fifty-four patients suffering from patellar tendinopathy were enrolled. After clinical (VAS and VISA-P) and sonographic evaluation, two ultrasound guided injections (2 weeks apart) of platelet rich plasma, high-volume image-guided injections of saline, or both in association were performed. The VAS and VISA-P scores obtained from the three treatments groups (18 patients in each group) were compared across the different follow-up times (3 and 6 months).

RESULTS

In the short term both treatments showed comparable efficacy, whereas in the medium term the positive effects of high-volume image-guided injections gradually diminished and platelet rich plasma showed greater efficacy. Better results (reduced pain, improved function and increased number of subjects who exhibited optimal recovery [> 20 points in VISA-P score]) were observed when both procedures were associated.

CONCLUSIONS

The contemporaneous administration of platelet rich plasma and high volume image guided injections of saline treatments, which influence tendon repair by means of different mechanisms, grants a greater improvement for patellar tendinopathy. This finding has clinical relevance, given that this condition has a substantial impact on sports and work performance.

LEVEL OF EVIDENCE

III.

Autologous fibrin scaffolds: When platelet- and plasma-derived biomolecules meet fibrin

The healing of vascularized mammalian tissue injuries initiate with hemostasis and clotting as part of biological defense system leading to the formation of a fibrin clot in which activated platelets are trapped to quickly stop bleeding and destroy microbials. In order to harness the therapeutic potential of biomolecules secreted by platelets and stemmed from plasma, blood deconstruction has allowed to yield autologous platelet-and plasma-derived protein fibrin scaffold. The autologous growth factors and microparticles stemmed from platelets and plasma, interact with fibrin, extracellular matrix, and tissue cells in a combinatorial, synergistic, and multidirectional way on mechanisms governing tissue repair. This interplay will induce a wide range of cell specifications during inflammation and repair process including but not limited to fibrogenesis, angiogenesis, and immunomodulation. As biology-as-a-drug approach, autologous platelet-and plasma-derived protein fibrin scaffold is emerging as a safe and efficacious natural human-engineered growth factor delivery system to repair musculoskeletal tissues, and skin and corneal ulcers and burns. In doing so, it acts as therapeutic agent not perfect but close to biological precision. However, this autologous, biocompatible, biodegradable, and long in vivo lasting strategy faces several challenges, including its non-conventional single dose-response effect, the lack of standardization in its preparation and application, and the patient's biological features. In this review, we give an account of the main events of tissue repair. Then, we describe the procedure to prepare autologous platelet-and plasma-derived protein fibrin scaffolds, and the rationale behind these biomaterials, and finally, we highlight the significance of strategic accuracy in their application.

Meta-analysis Comparing Autologous Blood-Derived Products (Including Platelet-Rich Plasma) Injection Versus Placebo in Patients With Achilles Tendinopathy

PURPOSE

To compare the effectiveness of autologous blood-derived products (ABP) injection with that of placebo (sham injection, no injection, or physiotherapy alone) in patients with Achilles tendinopathy.

METHODS

Electronic databases, including PubMed, Scopus, EMBASE, and Cochrane Library were searched up to June 2017. All published or unpublished randomized controlled trials (RCTs) were included. Two independent raters assessed the risk of bias of RCTs with the Cochrane Risk of Bias Tool. The primary outcome was Victorian Institute of Sports Assessment-Achilles (VISA-A) score. Weighted mean differences (WMDs) were used for random effect meta-analysis.

RESULTS

Seven RCTs were enrolled in meta-analysis. The ABP injection and placebo revealed equal effectiveness in VISA-A score improvement at 4 to 6 weeks (short term, WMD 2.29, 95% confidence interval [CI]: -1.69, 6.27), 12 weeks (medium term, WMD 2.63, 95% CI: -1.72, 6.98), 24 weeks (long term, WMD 4.61, 95% CI: -1.25, 10.47), and 48 weeks (very long term, WMD 4.16, 95% CI: -6.82, 15.14). In meta-regression, there was no association between change in VISA-A score and duration of symptoms at 4 to 6 weeks (short term), 12 weeks (medium term), and 24 weeks (long term).

CONCLUSIONS

This meta-analysis revealed that ABP injection was not more effective than placebo (sham injection, no injection, or physiotherapy alone) in Achilles tendinopathy and that no association was found between therapeutic effects and duration of symptoms.

LEVEL OF EVIDENCE

Level I, meta-analysis of Level I studies.

Italian consensus conference on guidelines for conservative treatment on lower limb muscle injuries in athlete

Provide the state of the art concerning (1) biology and aetiology, (2) classification, (3) clinical assessment and (4) conservative treatment of lower limb muscle injuries (MI) in athletes. Seventy international experts with different medical backgrounds participated in the consensus conference. They discussed and approved a consensus composed of four sections which are presented in these documents. This paper represents a synthesis of the consensus conference, the following four sections are discussed: (i) The biology and aetiology of MIs. A definition of MI was formulated and some key points concerning physiology and pathogenesis of MIs were discussed. (ii) The MI classification. A classification of MIs was proposed. (iii) The MI clinical assessment, in which were discussed anamnesis, inspection and clinical examination and are provided the relative guidelines. (iv) The MI conservative treatment, in which are provided the guidelines for conservative treatment based on the severity of the lesion. Furthermore, instrumental therapy and pharmacological treatment were discussed. Knowledge of the aetiology and biology of MIs is an essential prerequisite in order to plan and conduct a rehabilitation plan. Another important aspect is the use of a rational MI classification on prognostic values. We propose a classification based on radiological investigations performed by ultrasonography and MRI strongly linked to prognostic factors. Furthermore, the consensus conference results will able to provide fundamental guidelines for diagnostic and rehabilitation practice, also considering instrumental therapy and pharmacological treatment of MI. Expert opinion, level IV.

An evidence-based evaluation on the use of platelet rich plasma in orthopedics - a review of the literature

Within orthopedics, the use of platelet-rich plasma (PRP) has been rapidly increasing in popularity, however, its true effectiveness has yet to be fully established. Several studies find that injecting PRP to the site of injury does not provide any significant benefit with respect to clinical outcomes; however, many others report the contrary. Due to the conflicting evidence and multiple meta-analyses conducted on the topic, a literature review of high-quality evidence on the use of PRP for common orthopaedic conditions was performed. Thus far, the evidence appears to suggest that PRP may provide some benefit in patients who present with knee osteoarthritis or lateral epicondylitis. On the other hand, evidence appears to be inconsistent or shows a minimal benefit for PRP usage in rotator cuff repair, patellar and Achilles tendinopathies, hamstring injuries, anterior cruciate ligament (ACL) repair, and medial epicondylitis. There is limited confidence in the conclusions from the published meta-analyses due to issues with statistical pooling, and limited subgroup analyses exploring the substantial heterogeneity across studies. Evidence-based clinicians considering the use of PRP in their patients with musculoskeletal injuries should be weary that the literature appears to be inconsistent and thus far, inconclusive.

Achilles Tendon Open Surgical Treatment With Platelet-Rich Fibrin Matrix Augmentation: Biomechanical Evaluation

The relationship between surgical technique and ankle biomechanical properties after surgery for acute rupture of the Achilles tendon (ATR) has not yet been fully investigated. Platelet-rich fibrin (PRF) matrices seem to play a central role in the complex processes of tendon healing. Our aim was to analyze the biomechanical characteristics, stiffness, and mechanical work of the ankle during walking in patients who had undergone surgery after ATR with and without PRF augmentation. We performed a retrospective review of all consecutive patients who had been treated with surgical repair after ATR. Of the 20 male subjects enrolled, 9 (45%) had undergone conventional open repair of the Achilles tendon using the Krackow technique (no-PRF) and 11 (55%) had undergone surgery with PRF augmentation. An additional 8 healthy subjects were included as a control group. A gait analysis evaluation was performed at 6 months after surgery. The percentage of the stance time of the operated leg, double-support time of the healthy leg, and net work of the ankle during the gait cycle showed statistically significant differences between the no-PRF and the healthy group (p < .005). No differences were found between the PRF and healthy groups. Treatment with suture and PRF augmentation could result in significant functional improvements in term of efficiency of motion.

Comparison of Efficacy of Autologous Platelet-rich Fibrin versus Saline Dressing in Chronic Venous Leg Ulcers: A Randomised Controlled Trial

BACKGROUND

Venous leg ulcer is a chronic condition, and various treatment modalities are available. Platelet-rich fibrin (PRF) is one of the newer modalities and it contains fibroblast growth factor (GF), vascular endothelial GF, angiopoitin and platelet-derived GF which enhances the wound healing. Hence, we conducted a randomised controlled trial to compare the efficacy of PRF versus saline dressing in chronic venous leg ulcers.

AIM

This study aims to compare the efficacy of autologous PRF with saline dressing in patients with chronic venous leg ulcer and to compare the mean reduction in ulcer area at the end of 4 weeks.

MATERIALS AND METHODS

Fifteen patients with chronic venous leg ulcers of >6 months duration having an ulcer area of 1 cm × 1 cm to 5 cm × 5 cm were taken into the study and were randomly divided into two groups. Group 1: Patients received PRF dressing. Ten millilitres of patient's blood was taken and centrifuged at 3000 rpm for 15 min. A fibrin clot obtained in the middle of the tube was removed and used for dressing over the wound surface. It was repeated every week for 4 weeks. Group 2: Patients received saline dressings once a week for 4 weeks. The assessment of the ulcer size was done with the help of photographs, and ulcer area was measured.

RESULTS

The mean reduction in the area of the ulcer size in PRF group was 85.51%, and the mean reduction in the area of the ulcer size in Saline group was 42.74% which was statistically significant with a P < 0.001 and t = 4.11.

CONCLUSION

We conclude that PRF dressing can be used as it is effective, inexpensive, safe and an outpatient procedure.

Tangibility of platelet-rich fibrin matrix for nasolabial folds

BACKGROUND

Using autologous tissue is a simple process and ideal choice for augmentation of the soft facial tissue. In this regard, platelet-rich fibrin matrix (PRFM) is used for the correction of fine rhytids and nasolabial folds (NLFs) as well as facial augmentation. This study tries to evaluate the tangibility of PRFM for facial augmentation.

MATERIALS AND METHODS

In this study, 20 patients (20-45 years) were studied to examine the augmentation (4 patients were excluded). For each, 3cc of PRFM provided by using 35cc of autologous blood and injected through subdermal technique into NLFs. Thickness and volume of the tissue were measured before and 3 months after treatment by sonography. The collected data were analyzed through paired t-test and independent t-test by using SPSS version 19.0 (SPSS Inc., Chicago, IL, USA).

RESULTS

The study included 16 women, with average of 39.43 ± 6.84 years (age range, 20-45 years). The thickness and the volume of subcutaneous tissue in NLFs before and after treatment show no significant difference on the right side rather than on the left side (P > 0.05), but the thickness and the volume of the tissue on both sides after treatment shows significant increase rather than before treatment, so that this increase was significant statistically. This study shows that different right and left thickness was 0.54 ± 0.51 and 0.51 ± 0.38 (P ≤ 0.001). Further, different right and left volume was 0.25 ± 0.20 and 0.26 ± 0.22, respectively (P < 0.001).

CONCLUSION

According to the results, the increased tissue volume by PRFM still persists after 3 months of treatment and its retention has been effective on the healing process.

Effects of plasma rich in growth factors (PRGF) on biomechanical properties of Achilles tendon repair

PURPOSE

To assess the biomechanical effects of intra-tendinous injections of PRGF on the healing Achilles tendon after repair in a sheep model.

METHODS

Thirty sheep were randomly assigned into one of the six groups depending on the type of treatment received (PRGF or placebo) and survival time (2, 4 and 8 weeks). The Achilles tendon injury was repaired by suturing the tendinous edges employing a three-loop pulley pattern. A trans-articular external fixation system was then used for immobilization. The PRGF or placebo was administered on a weekly basis completing a maximum of three infiltrations. The force, section and tension values were compared between the operated and healthy Achilles tendons across all groups.

RESULTS

The PRGF-treated tendons had higher force at 8 weeks compared with the placebo group (p = 0.007). Between 2 and 4 weeks, a significant increase in force in both the PRGF-treated tendon (p = 0.0027) and placebo group (p = 0.0095) occurred. No significant differences were found for section ratio between PRGF-treated tendons and the placebo group for any of the time periods evaluated. At 2 weeks, PRGF-treated tendons had higher tension ratio compared with placebo group tendons (p = 0.0143). Both PRGF and placebo treatments significantly improved the force (p < 0.001 and p = 0.0095, respectively) and tension (p = 0.009 and p = 0.0039, respectively) ratios at 8 weeks compared with 2 weeks.

CONCLUSION

The application of PRGF increases Achilles tendon repair strength at 8 weeks compared with the use of placebo. The use of PRGF does not modify section and tension ratios compared with placebo at 8 weeks. The tension ratio progressively increases between 2 and 8 weeks compared with the placebo.

Concise Review: The Use of Adipose-Derived Stromal Vascular Fraction Cells and Platelet Rich Plasma in Regenerative Plastic Surgery

Tissue engineering has emerged at the intersection of numerous disciplines to meet a global clinical need for technologies to promote the regeneration of tissues. Recently, many authors have focused their attention on mesenchymal stem/stromal cells (MSCs) for their capacity to differentiate into many cell lineages. The most widely studied cell types are bone marrow mesenchymal stem cells and adipose-derived stem cells (ASCs), which display similar results. Biomaterials, cells, and growth factors are needed to design a regenerative plastic surgery approach in the treatment of organ and tissue defects, but not all tissues are created equal. The aim of this article is to describe the advances in tissue engineering through the use of ASCs, platelet rich plasma, and biomaterials to enable regeneration of damaged complex tissue. Stem Cells 2017;35:117-134.

Efficacy of freeze-dried platelet-rich plasma in bone engineering

OBJECTIVE

Platelet-rich plasma (PRP) is typically isolated and applied immediately after preparation, making it both a time- and labor-intensive addition to the operative procedure. Thus, it would be convenient if PRP could be preserved. We evaluated the efficacy of freeze-dried PRP (FD-PRP), as compared with freshly isolated PRP (f-PRP) for bone engineering.

DESIGN

FD-PRP was prepared by lyophilization of f-PRP and was subsequently preserved at -20°C for one month. It was then rehydrated with an equal or 1/3 amount of distilled water (×1FD-PRP, ×3FD-PRP, respectively), and we assessed its gelation properties and the release of growth factors (PDGF-BB, TGF-β1, and VEGF). We also examined the bone forming ability with onlay-grafting on mice calvaria using β-TCP granules as a scaffold.

RESULTS

FD-PRP showed comparable gelation as f-PRP. In terms of growth factor release,×1FD-PRP released identical concentrations of PDGF-BB and TGF-β1 to f-PRP, while ×3FD-PRP released approximately 3-fold concentrations when compared with f-PRP. In vivo, ×1FD-PRP promoted identical levels of the bone formation as f-PRP, and ×3FD-PRP induced more abundant bone formation.

CONCLUSIONS

These results suggest that f-PRP can be stored without functional loss by freeze-drying and the concentration of PRP may improve its efficacy in bone engineering.

A new strategy to tackle severe knee osteoarthritis: Combination of intra-articular and intraosseous injections of Platelet Rich Plasma

INTRODUCTION

Knee osteoarthritis (KOA) is a mechanically induced, cytokine and enzyme-mediated disorder involving all the joint tissue of the knee. Rebuilding a physiological-homeostatic network at the tissue level following knee organ failure, such as in severe KOA, is a daunting task with therapeutic targets encompassing the articular cartilage, synovium and subchondral bone. Intraarticular infiltration of plasma rich in growth factors (PRP) has emerged as a promising symptomatic approach, although it is insufficient to reach the subchondral bone.

AREAS COVERED

This review addresses current molecular and cellular data in joint homeostasis and osteoarthritis pathophysiology. In particular, it focuses on changes that subchondral bone undergoes in knee osteoarthritis and evaluates recent observations on the crosstalk among articular cartilage, subchondral bone and synovial membrane. In addition, we review some mechanistic aspects that have been proposed and provide the rationale for using PRP intraosseously in KOA.

EXPERT OPINION

The knee joint is a paradigm of autonomy and connectedness of its anatomical structures and tissues from which it is made. We propose an innovative approach to the treatment of severe knee osteoarthritis consisting of a combination of intraarticular and intraosseous infiltrations of PRP, which might offer a new therapeutic tool in KOA therapy.

Platelet Rich Plasma Therapy in Non-insertional Achilles Tendinopathy: The Efficacy is Reduced in 60-years Old People Compared to Young and Middle-Age Individuals

Background: Platelet Rich Plasma (PRP) has shown positive and long-lasting effects in patients with tendinopathies. However, information about age-related differences in the clinical outcome is limited. Aim of this retrospective study was to compare the efficacy of PRP therapy in young and elderly subjects suffering for Achilles tendinopathy.

Materials and method: Patients with recalcitrant non-insertional Achilles tendinopathy were enrolled. Clinical (VISA-A) and instrumental (ultrasonography) data were collected at baseline and after 1, 3, 6, and 12 months. PRP injections (once a week for 3 weeks) were performed in sterile conditions and under ultrasound (US) control.

Results: Forty-four subjects (29 young: mean age 39.5 ± 6.9; 15 elderly: mean age 61.5 ± 5.3) were retrospectively evaluated. At baseline, no significant differences were observed in the clinical and US parameters. Throughout the whole length of the study, a significant increase of VISA-A score was seen in both groups (from 50.3 ± 8.8 to 76.1 ± 6.6 in the young group, and from 48.7 ± 7.6 to 61.1 ± 9.4 in the elderly group); however, the infra-groups comparison showed better results in young patients, compared to the aged counterpart.

Conclusion: Our results show that PRP is less effective in aged people. This finding can be ascribed to several biochemical and biomechanical differences documented in tendons of young and elderly subjects (reduced number and functionality of tenocytes and tenoblasts), which becomes more evident in the long-term tissue healing. However, prospective trials, using different PRP preparations and enrolling a larger number of subjects, are needed to draw more sound and definitive conclusions.

Three-Dimensional Platelet-Rich Plasma Hydrogel Model to Study Early Tendon Healing

Since the experimental conditions of cell cultures may bias results, it is critical to use suitable models. This is also true in the context of tendon cell biology and the study of platelet-rich plasma (PRP) therapies and PRP-augmented cell-based therapies. We compared the culture of human tendon cells in 2 dimensions (2D) with PRP-supplemented media to culture in matching 3-dimensional (3D) PRP hydrogels. Cell proliferation, cell shape, and the pattern of gene and protein expression were examined. Our data revealed modifications in cell shape and enhanced expression of tenomodulin and scleraxis in 3D hydrogels. Additionally, protein secretion analysis using glass-based arrays specific for angiogenesis revealed differences in interleukin (IL)-6 and IL-8 protein expression between 2D cultures and 3D hydrogels, while the secretion of other angiogenic or inflammatory cytokines was unaffected. Our study suggests that 3D hydrogels are physiologically more relevant than 2D cultures in the study of tendon cells, based on cell shape, support of tenocyte proliferation, phenotype, and the pattern of gene and protein expression.