Platelet-rich plasma: from basic science to clinical applications

Wound dressings as growth factor delivery platforms for chronic wound healing

Introduction: Years of tissue engineering research have clearly demonstrated the potential of integrating growth factors (GFs) into scaffolds for tissue regeneration, a concept that has recently been applied to wound dressings. The old concept of wound dressings that only take a passive role in wound healing has now been overtaken, and advanced dressings which can take an active part in wound healing, are of current research interest.Areas covered: In this review we will focus on the recent strategies for the delivery of GFs to wound sites with an emphasis on the different approaches used to achieve fine tuning of spatial and temporal concentrations to achieve therapeutic efficacy.Expert opinion: The use of GFs to accelerate wound healing and reduce scar formation is now considered a feasible therapeutic approach in patients with a high risk of infections and complications. The integration of micro - and nanotechnologies into wound dressings could be the key to overcome the inherent instability of GFs and offer adequate control over the release rate. Many investigations have led to encouraging outcomes in various in vitro and in vivo wound models, and it is expected that some of these technologies will satisfy clinical needs and will enter commercialization.

Autologous Platelet Rich Plasma (PRP) in the treatment of elbow epicondylitis and plantar fasciitis: medium to long term clinical outcome

Background and aim:

Platelet-Rich-Plasma(PRP) is a popular biological therapy especially used to regenerate different musculoskeletal tissues by releasing growth-factors and cytokines promoting cell proliferation, chemotaxis, differentiation, and angiogenesis. The

aim

was to evaluate the clinical effectiveness and safety of PRP for Lateral-Epicondylitis (LE) of the elbow and Plantar-Fasciitis (PF).

Methods:

A retrospective study was conducted including patients treated with a single topic autologous-PRP-injection between 1-1-2009 and 7-18-2019 for LE or PF at our institution; patients operated for the same problem, patients refusing the study or not traceable were excluded. Patients were assessed with VAS for pain and clinical scales.

Results:

33 patients were treated with PRP and 13 (8F, 5M) included: 4LE and 9PF for a total of 16 cases. The average pain level was 0.61±0.63: 1±1.41 for LE and 0,44±0 for PF. No significant side effect was reported. 4 PRP-treatments failed: 2LE and 2PF. OES and PRTEE gave excellent results for elbow. Average foot scores were AOFAS 98.2±5 and FADI 91.3±1. Patients were stratified and compared according to plantar arch conformation, follow-up length, healing time, time from diagnosis to PRP-treatment, therapies before PRP (physiotherapy, steroid infiltration or shock-waves), risk factors (standing work, sport, age, sex).

Conclusions:

As in other studies, our results do not allow to draw sufficiently valid conclusions regarding the effectiveness and safety of PRP in the treatment of LE and PF: in particular the statistical significance is limited by the small sample size. PRP can be chosen as a non-first-line treatment for LE and PF.

Assisted therapy with platelet-rich plasma for burn patients: A meta-analysis and systematic review

INTRODUCTION

Platelet-rich plasma (PRP) therapy has been used in different medical fields, but its effectiveness in burn wound healing remains debatable. In this study, we performed a systematic review and meta-analysis of the available evidence on burn patients treated with PRP to evaluate the safety and efficacy of the treatment.

METHODS

Randomized controlled trials evaluating the efficacy of PRP in patients with burn injuries were selected. Eligible retrospective studies were abstracted and assessed for the risk of bias by two reviewers and results of mean time to complete epithelization and wound closure rate in the included studies were analyzed. Studies on the correlation between PRP and burn wound healing published in English or Chinese before March 2020 were retrieved from PubMed.

RESULTS

Eight studies (including 449 patients) met our inclusion criteria. Qualitative analysis revealed that compared with the control group, the PRP group had significantly better wound closure rates at weeks 2 (mean difference (MD): 12.79 [95% confidence interval (CI): 7.08, 18.49]; I2: 0%; p < 0.0001) and 3 (MD: 12.66 [95% CI: 5.97, 19.34]; I2: 55%; p = 0.0002) and time to complete epithelialization (MD: -3.45 [95% CI: -4.87, -2.04] (days); I2: 0%; p < 0.00001). There was no significant difference in infection rate or graft take rate.

CONCLUSIONS

PRP application can accelerate wound closure, however, it has no effect on the rates of wound infection and graft take rate.

Prolotherapy for the patients with chronic musculoskeletal pain: systematic review and meta-analysis

Background

Prolotherapy, which stimulates the healing of loosened ligaments and tendons, is a cost-effective and safe treatment modality for chronic musculoskeletal pain. Its benefits may be affected by injection protocols, comparative regimens, and evaluation scales. The aim of this study was to determine the effectiveness of dextrose prolotherapy as a long-term treatment for chronic musculoskeletal pain.

Methods

Medline, Embase, Cochrane Central, KoreaMed, and KMbase databases were searched for studies published up to March 2019. We included randomized controlled trials which compared the effect of dextrose prolotherapy with that of other therapies such as exercise, saline, platelet-rich plasma, and steroid injection. The primary outcome was pain score change during daily life.

Results

Ten studies involving 750 participants were included in the final analysis. Pain scores from 6 months to 1 year after dextrose prolotherapy were significantly reduced compared to saline injection (standardized mean difference [SMD] –0.44; 95% confidence interval [CI] –0.76 to –0.11, P = 0.008) and exercise (SMD –0.42; 95% CI –0.77 to –0.07, P = 0.02). Prolotherapy yielded results similar to platelet-rich plasma or steroid injection, that it showed no significant difference in pain score.

Conclusions

Dextrose prolotherapy is more effective in the treatment of chronic pain compared to saline injection or exercise. Its effect was comparable to that of platelet-rich plasma or steroid injection. Adequately powered, homogeneous, and longer-term trials are needed to better elucidate the efficacy of prolotherapy.

Extract from Rostellularia procumbens (L.) Nees Inhibits Thrombosis and Platelet Aggregation by Regulating Integrin β3 and MAPK Pathways

AIM OF STUDY

The main objective of this study was to investigate the antithrombotic and antiplatelet effect of the extract from Rostellularia procumbenss (L.) Nees and understand the mechanisms by which it exerts its antithrombotic and antiplatelet mechanisms.

MATERIALS AND METHODS

The antithrombotic effective parts (RPE) were isolated using D101 macroporous adsorption resin and potential active ingredients (JAC) were isolated using the preparative liquid-phase method. The lactate dehydrogenase kit was used to determine the toxicity of RPE and JAC to platelets. The antiadhesion effect of RPE and JAC on platelets was observed by fluorescence microscopy with rhodamine phalloidin. Antithrombotic efficacy of RPE and JAC in vivo was evaluated by establishing a rat tail thrombosis model. Contents of p-selectin, TXB₂, and 6-keto-PGF_1α in rat serum were measured using an enzyme-linked immunosorbent (ELISA) assay, and the rat black tail rate was measured to prove the protective effect of RPE and JAC on the tail thrombus rat model. Western blot was used for detection of serum-related proteins in the tail thrombus rat model.

RESULTS

The results showed that RPE had antithrombotic and antiplatelet effects. RPE and JAC have no toxicity to platelets. In vitro experiments showed that RPE and JAC had antiadhesion effects on platelets. In vivo experiments showed that RPE significantly inhibited the increase of p-selectin and TXB₂ and significantly increased the content of 6-keto-PGF_1α in the serum of rats. Western blot results demonstrated that RPE and JDB significantly inhibited the phosphorylation of the MAPK protein family in the platelets of rats, and RPE also significantly inhibited the phosphorylation of β₃ protein.

CONCLUSIONS

RPE has antithrombotic and antiplatelet activity in vivo and vitro. Its mechanism may be via preventing integrin α_IIbβ₃ activation, which in turn leads to the inhibition of the phosphorylation of the MAPK family and further suppresses TXA₂, which leads to the antithrombotic and antiplatelet effects.

Quality comparison between two different types of platelet-rich plasma for knee osteoarthritis

Introduction: Knee osteoarthritis (KOA), the most common form of osteoarthritis (OA) is a considerable health concern worldwide. Platelet-rich plasma (PRP) is a common therapeutic option for KOA. Different types of PRPs have varying efficacies. However, a comparative analysis of the qualities of these PRPs is lacking. Methods: Two types of PRPs, including autologous protein solution (APS), and leukocyte-poor PRP (LP-PRP) along with whole blood (WB) and platelet-poor plasma (PPP) were characterized for platelet content, leukocyte content, and composition in 10 healthy volunteers (HV) (the controlled laboratory study) and 16 KOA patients (a retrospective observational study). Additionally, the levels of the platelet-derived growth factor (PDGF)-BB, and different cytokines were estimated in HV. Results: In HV, the concentrations of platelets and leukocytes, levels of different cytokines, including interleukin 1 receptor antagonist (IL-1Ra), soluble TNF receptor type II (sTNF-RII), and IL-1β, and the ratio of IL-1Ra/IL-1β were significantly higher in APS, whereas the PDGF-BB was higher in LP-PRP than APS. In KOA patients, a higher concentration of platelets was observed in LP-PRP, and a higher concentration of leukocytes was observed in APS than LP-PRP. Following the PAW classification system, LP-PRP was classified as P2-B type in HV (51.3 × 10⁴/μl) and KOA (53.4 × 10⁴/μl), whereas APS was classified as P3-A type in HV (110.1 × 10⁴/μl) and P2-A type in KOA (29.0 × 10⁴/μl). In a retrospective observational study, the KOA patients who underwent APS injection had a higher incidence of arthralgia, and this arthralgia lasted for a longer time than LP-PRP injection in the same individual. Discussion: The quality of the two PRPs differed distinctively depending on their preparation methods, which might affect their clinical efficacies and adverse events. Therefore, the characterization of these parameters should be prioritized while choosing PRP.

Platelet-Rich Plasma Augmentation for Isolated Arthroscopic Meniscal Repairs Leads to Significantly Lower Failure Rates: A Systematic Review of Comparative Studies

Background:

Studies have reported relatively high failure rates of isolated meniscal repairs. Platelet-rich plasma (PRP) has been suggested as a way to increase growth factors that enhance healing.

Purpose:

To compare (1) meniscal repair failures and (2) patient-reported outcomes after isolated arthroscopic meniscal repair augmented with and without PRP.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

A systematic review was performed using the PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines. Multiple databases were searched for studies that compared outcomes of isolated arthroscopic meniscal repair augmented with PRP versus without PRP in human patients. Failures and patient-reported outcome scores were reported for each study and compared between groups. Study heterogeneity was assessed using I² for each outcome measure before meta-analysis. Study methodological quality was analyzed. Continuous variable data were reported as mean and standard deviation from the mean. Categorical variable data were reported as frequency with percentage. All P values were reported with significance set at P < .05.

Results:

Five articles were analyzed (274 patients [110 with PRP and 164 without PRP]; 65.8% male; mean age, 29.1 ± 4.6 years; mean follow-up, 29.2 ± 22.1 months). The risk of meniscal repair failure ranged from 4.4% to 26.7% for PRP-augmented repairs and 13.3% to 50.0% for repairs without PRP. Meniscal repairs augmented with PRP had significantly lower failure rates than repairs without PRP (odds ratio, 0.32; 95% CI, 0.12-0.90; P = .03). One of the 5 studies reported significantly higher outcomes in the PRP-augmented group versus the no-PRP group for the International Knee Documentation Committee (IKDC), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee injury and Osteoarthritis Outcome Score (KOOS) (P < .05 for all). The remaining 4 studies reported no significant difference between groups with regard to outcomes for the IKDC, Lysholm knee scale, visual analog scale for pain, or Tegner activity level.

Conclusion:

Although the studies were of mostly of low quality, isolated arthroscopic meniscal repairs augmented with PRP led to significantly lower failure rates (10.8% vs 27.0%; odds ratio, 0.32; P = .03) as compared with repairs without PRP. However, most studies reported no significant differences in patient-reported outcomes.

Platelet-rich plasma for laryngotracheal reconstruction: an experimental study

OBJECTIVES/HYPOTHESIS

This study was designed to evaluate the graft healing effect of topical application of platelet-rich plasma (PRP) for laryngotracheal reconstruction (LTR) in a rabbit model.

STUDY DESIGN

It is a prospective randomized control animal study.

MATERIALS AND METHODS

Sixteen healthy New Zealand White rabbits were assigned to two groups of eight animals each. The control group underwent LTR with anterior auricular cartilage graft. The PRP group underwent the same surgical procedure plus PRP application over the anastomosis and surgical field. Two animals in the PRP group and two animals in control group died due to severe respiratory distress on postoperative days 10, 12, 15, and 18. Six rabbits (n = 3 for control group and n = 3 for PRP group) were sacrificed at 4 weeks, and six rabbits (n = 3 for control group and n = 3 for PRP group) were sacrificed at 8 weeks. Laryngotracheal regions were evaluated histopathologically.

RESULTS

Macroscopically, the average anteroposterior and lateral diameter of the reconstructed region and the degree of lumen patency on postoperative 4th week and 8th week were not statistically different among two groups. There was no significant difference between the groups in terms of any of the microscopic findings when the analysis was made separately. However, analysis of the total number of rabbits has shown that new cartilage formation and angiogenesis were more pronounced in PRP group than control group.

CONCLUSIONS

Application of PRP contributed to better healing in airway surgery by promoting a release of growth factors that stimulate new cartilage formation and angiogenesis.

Editorial Commentary: Human Granulocyte-Stimulating Factor Increases the Leukocyte Richness of Platelet-Rich Plasma

Platelet-rich plasma (PRP) is the most common treatment in orthobiologis, because PRP is safe, low cost, and minimally invasive and could be used to promote the tissue-repair process. The systemic mobilization with human granulocyte-stimulating factor increased concentrations of white blood cells and monocyte but not platelets in PRP. It may enhance the efficacy of PRP therapy via monocytes/macrophages. Improving the efficacy of PRP therapy, bone marrow aspirate, mesenchymal stems cells, or other orthobiologics is not simple because there are many variations in products and patient factors.

Biologics to Improve Healing in Large and Massive Rotator Cuff Tears: A Critical Review

Large and massive rotator cuff tears have the highest risk of retear. Common biologic modalities that can potentially reduce the retear rate and improve healing include platelet-rich plasma (PRP), scaffolds, and mesenchymal stem cells (MSCs). PRP has been studied for its role in improving rotator cuff healing and results of randomized controlled trials and meta-analyses show mixed results. Most studies in large and massivge tears show that PRP decreases the retear rate, but the connection between structural integrity and clinical outcomes is still unknown. Extracellular matrix (ECM) and synthetic scaffolds can increase healing in augmentation and bridging repair. Acellular dermal allografts have shown better healing rates and outcomes than xenografts in meta-analyses. Synthetic scaffolds augmented with bone marrow-derived stem cells have only been studied in vitro but are promising for the combination of mechanical stability and induction of a biological response. Superior capsule reconstruction is an exciting type of interposition graft reconstruction that has shown favorable early clinical outcomes for large and massive tears. Bone marrow-derived stem cells and adipose-derived stem cells improve the biomechanical characteristics of tendon repair and enhance the histological findings of the healing process in animal studies. However, evidence from human studies is lacking, especially in patients with large and massive tears. In summary, there are many biological options to augment rotator cuff repair in patients with large and massive tears. Due to mixed results and a lack of standardization in high-quality studies, we cannot recommend PRP at this time as an adjunct to rotator cuff repair. Both ECM and synthetic scaffolds, as well as SCR, can be used, especially in situations where native tendon is compromised, and additional mechanical augmentation is needed. Stem cells have been the least studied to date, so it is difficult to give recommendations for or against their use at this time.

Parylene-Based Porous Scaffold with Functionalized Encapsulation of Platelet-Rich Plasma and Living Stem Cells for Tissue Engineering Applications

A scaffold was fabricated to synergistically encapsulate living human adipose-derived stem cells (hASCs) and platelet-rich plasma (PRP) based on a vapor-phase sublimation and deposition process. During the process, ice templates were prepared using sterile water as the solvent and were used to accommodate the sensitive living cells and PRP molecules. Under controlled processing conditions, the ice templates underwent vapor sublimation to evaporate water molecules, while at the same time, vapor-phase deposition of poly-p-xylylene (Parylene, USP Class VI highly biocompatible) occurred to replace the templates, and the final construction yielded a scaffold with Parylene as the matrix, with simultaneously encapsulated living hASCs and PRP molecules. Evaluation of the fabricated synergistic scaffold for the proliferation activities toward the encapsulated hASCs indicated significant augmentation of cell proliferation contributed by the PRP ingredients. In addition, osteogenic activity in the early stage by alkaline phosphatase expression and later stage with calcium mineralization indicated significant enhancement toward osteogenetic differentiation of the encapsulated hASCs, which were guided by the PRP molecules. By contrast, examinations of adipogenic activity by lipid droplet formation revealed an inhibition of adipogenesis with decreased intracellular lipid accumulation, and a statistically significant downregulation of adipogenic differentiation was postulated for the scaffold products when compared to the osteogenetic results and the control experiments. The reported fabrication method featured a clean and simple process to construct scaffolds that combined delicate living hASCs and PRP molecules inside the structure. The resultant synergistic scaffold and the selected commercially available hASCs and PRP are emerging as tissue engineering tools that provide multifunctionality for tissue repair and regeneration.

Biologics

Biologics are a growing field that has shown immense promise for the treatment of musculoskeletal conditions both in orthopedic sports medicine and interventional pain management. These procedures utilize injection of supraphysiologic levels of platelets and growth factors to invoke the body's own inflammatory cascade to augment the healing of many bony and soft tissue conditions. While many patients improve with conservative care, there is a need to address the gap between those that improve with rehabilitation alone and those who ultimately require operative management. Orthobiologic procedures have the potential to fill this void. The purpose of this review is to summarize the basic science, evidence for use, and post-injection rehabilitation concepts of platelet-rich plasma (PRP) and mesenchymal stromal cells (MSCs) as they pertain to joints, tendons, ligaments, and the spine.

Leucocyte-poor-platelet-rich plasma intra-operative injection in chondral knee injuries improve patients outcomes. A prospective randomized trial

PURPOSE

Evaluate the effects of intra-operative leucocyte-poor-platelet-rich plasma (PRP) (type P3-Bβ with endogenous activation) injection in International Cartilage Repair Society (ICRS) grade III knee chondral injuries treated by chondroplasties, to increase and ameliorate the repair tissue.

METHODS

Patients were divided into two groups. Group A (control) consisted of 31 patients and Group B (PRP) 33 patients, totaling 64 patients analyzed. Patients also could had associated injuries (meniscal and/or ACL) being equally divided between both groups to avoid bias. PRP was injected at the end of surgery in group B. The patient outcomes were assessed using subjective International Knee Documentation Committee (IKDC) form, Knee Injury and Osteoarthritis Outcome Score (KOOS), and Tegner activity forms, prior to the surgery and three, six, 12, and 24 months after surgery (medium-term follow up).

RESULTS

IKDC and KOOS scores showed increase at each evaluation time points after surgery in both groups, but the treated Group (B) showed a higher increase with statistically significant difference. The Tegner activity scores were higher for the treated group only at six and 12 months.

CONCLUSION

Based on the subjective IKDC, KOOS, and Tegner scores, those patients affected by ICRS grade III chondral injuries undergoing arthroscopic chondroplasty who were also treated with PRP showed better and faster outcomes than the control group. Independently from the associated injury (meniscal or ACL). This difference could be measured for up to two years.

Gaelic Sport Injuries

The Gaelic sports of hurling and football, native to Ireland, are increasing in popularity worldwide. The injury profile of these sports requires multidisciplinary management by sports physicians, orthopaedic surgeons, and musculoskeletal (MSK) radiologists, among others. Advances in imaging modalities and interventional techniques have aided the diagnosis and treatment of sport injuries. In this article, we review the literature and our own institutional experience to describe common injury patterns identified in Gaelic games athletes, their main imaging features and relevant therapeutic interventions. We discuss the increasing prevalence of imaging services at sporting events and the central role of MSK radiologists in sports injury management.

Coaxial nanofiber scaffold with super-active platelet lysate to accelerate the repair of bone defects

To develop biocomposite materials with the local sustained-release function of biological factors to promote bone defect repair, coaxial electrospinning technology was performed to prepare a coaxial nanofiber scaffold with super-active platelet lysate (sPL), containing gelatin/PCL/PLLA. The nanofibers exhibited a uniform bead-free round morphology, observed by a scanning electron microscope (SEM), and the core/shell structure was confirmed by a transmission electron microscope (TEM). A mixture of polycaprolactone and sPL encapsulated by hydrophilic gelatin and hydrophobic l-polylactic acid can continuously release bioactive factors for up to 40 days. Encapsulation of sPL resulted in enhanced cell adhesion and proliferation, and sPL loading can increase the osteogenesis of osteoblasts. Besides, in vivo studies demonstrated that sPL-loaded biocomposites promoted the repair of skull defects in rats. Therefore, these results indicate that core-shell nanofibers loaded with sPL can add enormous potential to the clinical application of this scaffold in bone tissue engineering.

Hyaluronic acid and platelet-rich plasma for the management of knee osteoarthritis

PURPOSE

Symptomatic knee osteoarthritis (OA) remains a substantial cause of pain and disability worldwide and effective management in young patients without indications for total knee arthroplasty remains challenging. Intra-articular injections represent a viable option in the non-operative treatment of knee OA. Hyaluronic acid (HA) and platelet-rich plasma (PRP) are two commonly utilized intra-articular treatment modalities that are of particular clinical interest in the current literature. The purpose of this manuscript is to provide a concise review of the current literature on the use of HA, PRP, and HA-PRP conjugates for the treatment of symptomatic knee OA.

METHODS

A review of the literature utilizing PubMed, OVID/Medline, and Cochrane databases on basic science and clinical literature pertaining to preparation, composition, and outcomes of HA, PRP, and HA-PRP conjugates in patients with symptomatic knee OA.

RESULTS

Both HA and PRP have been shown to be efficacious for the treatment of symptomatic knee OA, with HA injections providing limited short-term improvement, while PRP may provide greater therapeutic relief, particularly with the use of leukocyte-poor (LP-PRP) formulations. Despite limited data, the combination of different formulations of HA-PRP conjugates may provide a synergistic effect, resulting in a clinically significant improvement in both pain and function.

CONCLUSION

In patients with symptomatic knee OA, intra-articular HA and PRP provide short-term improvement in pain and function, while the efficacy of HA-PRP conjugates warrants further study.

A Simple Drug Delivery System for Platelet-Derived Bioactive Molecules, to Improve Melanocyte Stimulation in Vitiligo Treatment

Vitiligo is the most common depigmentation disorder of the skin. Currently, its therapy focuses on the halting of the immune response and stimulation of the regenerative processes, leading to the restoration of normal melanocyte function. Platelet-rich plasma (PRP) represents a safe and cheap regenerative therapy option, as it delivers a wide spectrum of native growth factors, cytokines and other bioactive molecules. The aim of this study was to develop a simple delivery system to prolong the effects of the bioactive molecules released from platelets. The surface of electrospun and centrifugally spun poly-ε-caprolactone (PCL) fibrous scaffolds was functionalized with various concentrations of platelets; the influence of the morphology of the scaffolds and the concentration of the released platelet-derived bioactive molecules on melanocytes, was then assessed. An almost two-fold increase in the amount of the released bioactive molecules was detected on the centrifugally spun vs. electrospun scaffolds, and a sustained 14-day release of the bioactive molecules was demonstrated. A strong concentration-dependent response of melanocyte to the bioactive molecules was observed; higher concentrations of bioactive molecules resulted in improved metabolic activity and proliferation of melanocytes. This simple system improves melanocyte viability, offers on-site preparation and is suitable for prolonged topical PRP administration.

The Effects of Platelet-Rich and Platelet-Poor Plasma on Biological Characteristics of BM-MSCs In Vitro

Platelet-rich plasma (PRP) and its byproduct platelet-poor plasma (PPP) are rich sources of cytokines in tissue damage repair. Bone marrow-derived mesenchymal stem cells (BM-MSCs) have received more and more attention for their ability to treat multiple diseases. The purpose of our study was to investigate the biologic action of PPP and PRP on BM-MSCs. The adipogenic potential of BM-MSCs revealed no obvious change, but the osteogenic ability of BM-MSCs was enhanced after treated with PRP. CCK8 assays and cell colony formation assays showed that PRP promoted cell proliferation, while this effect of PPP was not obvious. No obvious difference was found in cell cycle and apoptosis of BM-MSCs between PRP and PPP treatment. Expression of β-galactosidase, a biological marker of senescence, was decreased upon PRP treatment which indicated that PRP provided significant protection against cellular senescence. The migratory capacity of BM-MSCs was detected by scratch and transwell assays. The results indicated that PRP could affect the migration ability of BM-MSCs. From immunofluorescence detection and western blot, we demonstrated that the level of epithelial-mesenchymal transition-related proteins was changed and several pluripotency marker genes, including Sox2, Sall4, Oct4, and Nanog, were increased. Finally, the expression of the key signal pathway such as PI3K/AKT was examined. Our findings suggested that PRP promoted cell migration of BM-MSCs via stimulating the signaling pathway of PI3K/AKT.

Novel transplant of combined platelet-rich fibrin Releasate and bone marrow stem cells prevent bone loss in Ovariectomized osteoporotic mice

BACKGROUND

Osteoporosis is a metabolic bone disorder characterized by deterioration in the quantity and quality of bone tissue, with a consequent increase susceptibility to fracture.

METHODS

In this study, we sought to determine the efficacy of platelet-rich fibrin releasates (PRFr) in augmenting the therapeutic effects of stem cell-based therapy in treating osteoporotic bone disorder. An osteoporosis mouse model was established through bilateral ovariectomy on 12-week-old female ICR (Institute of Cancer Research) mice. Eight weeks postoperatively, the ovariectomized (OVX) mice were left untreated (control) or injected with PRFr, bone marrow stem cells (BMSCs), or the combination of BMSCs and PRFr. Two different injection (single versus quadruple) dosages were tested to investigate the accumulative effects of BMSCS and PRFr on bone quality. Eight weeks after injection, the changes in tibial microstructural profiles included the percentage of bone volume versus total tissue volume (BV/TV, %), bone mineral density (BMD, g/cm3), trabecular number (Tb.N, number/mm), and trabecular separation (Tb.Sp, mm) and bony histology were analyzed.

RESULTS

Postmenopausal osteoporosis model was successfully established in OVX mice, evidenced by reduced BMD, decreased BV/TV, lower Tb.N but increased Tb.Sp. Eight weeks after injection, there was no significant change to BMD and bone trabeculae could be detected in mice that received single-injection regimen. In contrast, in mice which received 4 doses of combined PRFr and BMSCs, the BMD, BV/TV, and TB.N increased, and the TB.Sp decreased significantly compared to untreated OVX mice. Moreover, the histological analysis showed the trabecular spacing become narrower in OVX-mice treated with quadruple injection of BMSCs and combined PRFr and BMSCs than untreated control.

CONCLUSION

The systemic administration of combined BMSCs and PRFr protected against OVX-induced bone mass loss in mice. Moreover, the improvement of bony profile scores in quadruple-injection group is better than the single-injection group, probably through the increase in effect size of cells and growth factors. Our data also revealed the combination therapy of BMSCs and PRFr has better effect in enhancing osteogenesis, which may provide insight for the development of a novel therapeutic strategy in osteoporosis treatment.

Vivostat Platelet-Rich Fibrin® for Complicated or Chronic Wounds-A Pilot Study

Vivostat Platelet-Rich Fibrin^® (PRF) is an autologous platelet concentrate used for the local treatment of chronic or complicated wounds. Still, its application for this indication is not evidence-based. Therefore, we performed this monocentric retrospective pilot study investigating the clinical outcome of a local treatment of chronic or complicated wounds in 35 patients (23 male, 12 female, mean age 68.7 years) treated with Vivostat PRF^®. This study population is the largest among published studies analyzing the clinical efficacy of Vivostat PRF^® on chronic wounds so far. Using the perpendicular method we divided the wounds into three sizes (<10, 10–30, and >30 cm²). The clinical efficacy of the Vivostat PRF treatment was the primary endpoint and was divided into three groups of increasing degrees of wound improvement: (1) no improvement of the wound (wound area was not reduced > 10% under Vivostat PRF^® treatment), (2) improvement of the wound (reduced area > 10% under Vivostat PRF^® treatment) and (3) complete epithelialization (wounds that were completely re-epithelialized after Vivostat PRF^® treatment). We included patients’ diagnosis and concomitant diseases (peripheral arterial occlusive disease (PAOD)), chronic venous insufficiency (CVI)), diabetic foot syndrome (DFS)) in our data analysis in order to investigate their potential impact on the wound healing capacity of Vivostat PRF^®. Our results show that in the entire study population, 13 out of 35 (37.1%) patients experienced wound improvement and 14 out of 35 (40%) patients showed complete epithelialization of their wound under Vivostat PRF^® treatment. In summary, 77.1% of the treated patients benefited from the Vivostat PRF^® therapy. These positive wound healing effects were all observed within the first three to six Vivostat PRF^® applications. Subgroup analyses showed that Vivostat PRF^® appeared to be more efficient in patients without CVI in comparison to patients with CVI (p = 0.02). Moreover, Vivostat PRF^® treatment seems to be particularly efficient in PAOD-related wounds with a reduced crural arterial blood supply (p = 0.01). Additionally, we performed an experimental human in vivo study on ten male students where we artificially generated bilateral gluteal wounds and analyzed the influence of the Vivostat PRF^® treatment on the expression of two genes (human beta Defensin-2, ((hBD-2) and human beta-Defensin-3 (hBD-3)) in keratinocytes of resected wound specimens that are induced during wound healing. Interestingly, this analysis revealed that only seven of out ten individuals showed a relevant hBD-2 and hBD-3 gene induction after Vivostat PRF^® treatment. This led to the novel “key-lock-hypothesis”. With the goal of an individualized precision medicine approach with optimized wound treatment strategies in the future, this is an important observation that demands further experimental and clinical studies.

Characterization of a purified exosome product and its effects on canine flexor tenocyte biology

Flexor tendon injuries and tendinopathy are very common but remain challenging in clinical treatment. Exosomes-based cell-free therapy appears to be a promising strategy for tendon healing, while limited studies have evaluated its impacts on tenocyte biology. The objective of this study was to characterize a novel purified exosome product (PEP) derived from plasma, as well as to explore its cellular effects on canine tenocyte biology. The transmission electron microscope revealed that exosomes of PEP present cup-shaped structures with the diameters ranged from 80 to 141 nm, and the NanoSight report presented that their size mainly concentrated around 100 nm. The enzyme-linked immunosorbent assay kits analysis showed that PEP was positive for CD63 and AChE expression, and the cellular uptake of exosomes internalized into tenocyte cytoplasm was observed. The cell growth assays displayed that tenocyte proliferation ability was enhanced by PEP solution in a dose-dependent manner. Tenogenic phenotype was preserved as is evident by that tendon-related genes expression (SCX, COL1A, COL3A1, TNMD, DCN, and MKX) were expressed insistently in a high level, while tenocytes were treated with 5% PEP solution. Furthermore, migration capability was maintained and total collagen deposition was increased. More interesting, dexamethasone-induced cellular apoptosis was attenuated during the incubation of tenocytes with a 5% PEP solution. These findings will provide the basic understandings about the PEP, and support the potential use of this biological strategy for tendon healing.

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

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

Comparative efficacy of treatments for patients with knee osteoarthritis: a network meta-analysis

Background

Knee osteoarthritis is a common cause of musculoskeletal pain and a leading cause of disability and healthcare economic burden. The optimum treatment for knee osteoarthritis is still inconclusive. A network meta-analysis is required to assess the efficacy and safety of treatments and provide more scientific medical evidence.

Methods

Relevant studies were searched through PubMed, Embase, and Cochrane Library electronic databases from the inception to October 2018. Continuous outcomes such as pain, stiffness, physical function and total scores were expressed as the mean differences with 95% credible interval. Surface under the cumulative ranking curve illustrated the rank probability of each therapy under different outcomes.

Results

Nineteen studies were included in this study, with a total of 2395 patients. For knee pain, platelet-rich plasma (0.691) was ranked at the first place, followed by hyaluronic acid combined with platelet-rich plasma (0.670) and hyaluronic acid (0.402). In terms of stiffness, hyaluronic acid combined with platelet-rich plasma (0.743) enjoyed the highest value, platelet-rich plasma (0.603) was the next and hyaluronic acid (0.386) was the third. As for physical function, the rank was hyaluronic acid combined with platelet-rich plasma (0.772), platelet-rich plasma (0.608) and hyaluronic acid (0.343). For total scores, the order given by surface under the cumulative ranking was hyaluronic acid combined with platelet-rich plasma (0.765), platelet-rich plasma (0.624) and hyaluronic acid (0.37).

Conclusions

Hyaluronic acid combined with platelet-rich plasma showed the best efficacy in improving stiffness, physical function, and total scores, while platelet-rich plasma appeared the best in terms of pain reduction.

Meta-analysis Comparing Platelet-Rich Plasma vs Hyaluronic Acid Injection in Patients with Knee Osteoarthritis

PURPOSE

The purpose of this meta-analysis was to compare platelet-rich plasma (PRP) and hyaluronic acid (HA) in patients with knee osteoarthritis (KOA).

METHODS

Randomized controlled trials (RCTs) comparing the use of PRP and HA in KOA patients were retrieved from each database from the establishment date to April 2018. Outcome measurements were the Western Ontario and McMaster Universities Arthritis Index (WOMAC), visual analog scale (VAS), International Knee Documentation Committee, and Lequesne Index scores and adverse events. The pooled data were evaluated with Review Manager 5.3.5.

RESULTS

Fifteen RCTs (N = 1,314) were included in our meta-analysis. The present meta-analysis indicated that PRP injections reduced pain more effectively than HA injections in patients with KOA at six and 12 months of follow-up, as evaluated by the WOMAC pain score; the VAS pain score showed a significant difference at 12 months. Moreover, better functional improvement was observed in the PRP group, as demonstrated by the WOMAC function score at three, six, and 12 months. Additionally, PRP injections did not display different adverse event rates compared with HA injections.

CONCLUSION

In terms of long-term pain relief and functional improvement, PRP injections might be more effective than HA injections as a treatment for KOA. The optimal dosage, the timing interval and frequency of injections, and the ideal treatment for different stages of KOA remain areas of concern for future investigations.

Platelet-rich plasma (PRP) accelerates murine patellar tendon healing through enhancement of angiogenesis and collagen synthesis

PURPOSE

Although platelet-rich plasma (PRP) therapy has become an increasingly popular treatment for sports-related injuries, the molecular mechanisms of PRP on tissue healing process remain poorly understood. The aim of the present study was to develop an experimental method quantifying the efficacy of PRP with murine patellar tendon injury model, leading to future elucidation of the mechanisms of PRP on healing processes.

METHODS

Full-thickness defects were created in the central third of the murine patellar tendon. The prepared allogenic PRP gel was applied on the defect of the patellar tendon (PRP group), while the remaining mice served as the untreated control group. Mice were sacrificed at 2, 4, 6, 8, and 10 weeks after the operation, with histological sections obtained in each time point (n = 4 / time point / group). Semi-quantitative histological evaluation was performed in accordance with the Bonar score. The variables included in this scoring system were cell morphology, ground substance, collagen arrangement, and vascularity, with higher grades indicating worse tendon structures. In addition, the ratio of the collagen fibers to the entire tendon tissue (FT ratio) was measured using KS400 software as a quantitative histological evaluation.

RESULTS

The total Bonar score in the PRP group was significantly lower than in control group. With regard to the variables in the Bonar score, the vascularity score was significantly higher in the PRP group at 2 and 4 weeks, while the collagen arrangement score was significantly lower in the PRP group at 8 weeks. Based on a quantitative evaluation, the recovery speed of the patellar tendon determined by FT ratio was significantly faster in the PRP group than in the control group at 6 and 8 weeks.

CONCLUSIONS

We have developed an experimental method for histological and quantitative evaluation of the effects of PRP on tissue healing using murine patellar tendon injury model. The results of this study suggest that the local application of PRP could enhance the tissue-healing process both directly through action on localized cells and indirectly through the recruitment of reparative cells through the blood flow. Further investigations will be needed to confirm the mechanisms of PRP in tissue-healing processes with the development of this experimental model.

The use of PRP in treatment of Achilles Tendinopathy: A systematic review of literature. Study design: Systematic review of literature

BACKGROUND

Chronic Achilles Tendinopathy is a common condition that can be challenging to treat. There are many modalities used as treatment ranging from physiotherapy, injections, shockwave therapy to surgical intervention. Platelet Rich Plasma (PRP) has increased in popularity recently as a treatment option for Achilles Tendinopathy. It contains growth factors that might accelerate healing and speed up the recovery of this condition. Many studies have been conducted in the last few years to assess the effectiveness of this treatment method. However, there was controversy as to whether PRP had a beneficial effect on chronic Achille tendinopathy.

AIM

This systematic review of the literature was conducted to ascertain the efficacy of Platelet Rich Plasma (PRP) as a treatment option in chronic Achilles tendinopathy.

METHODS

PRISMA reporting item for systematic review has been used to conduct the selection, Electronic databases included PubMed, EMBASE, Cochrane collaborate, Google scholar, the web of science and Cochrane Library were searched for all RCT, prospective and retrospective studies conducted between January 2010 to February 2019. The quality of each study was evaluated using the Oxford CEBM tool to assess the articles for validity, relevance, and applicability of the results. A total number of 288 were found, and only 11 met the inclusion criteria.

RESULTS

5 Randomised control trials, 4 prospective and 2 retrospective cohort study were included in this systematic review. A total number of 406 patients were treated for non-insertional Achilles tendinopathy of which 230 patients had PRP local injection under Ultrasound guide.

CONCLUSION

Although many of the retrospective studies suggested an advantage of using PRP, the higher level of evidence studies do not support a significant efficacy. This systematic review showed very promising results from the use of Platelet Rich Plasma demonstrated by a significant improvement in the VAST-A score, but we certainly need decent size randomised control trials to show better and more accurate results.

Systemic Review: Is an Intradiscal Injection of Platelet-Rich Plasma for Lumbar Disc Degeneration Effective?

Current studies evaluating the outcomes of intradiscal platelet-rich plasma (PRP) injections in degenerative disc disease (DDD) are limited. The purpose of this review was to determine if an intradiscal injection of PRP for degenerative discs results in a statistically significant improvement in clinical outcomes. A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Level I-IV investigations of intradiscal PRP injections in DDD were sought in multiple databases. The Modified Coleman Methodology Score (MCMS) was used to analyze the methodological quality of the study. Only the outcome measurements used by more than 50% of the studies were included in the data analysis. The study heterogeneity and nature of evidence (mostly retrospective, non-comparative) precluded meta-analysis. Pre and post-injection pain visual analog scales (VAS) were compared using two sample Z-tests. Five articles (90 subjects, mean age 43.6 ± 7.7 years, mean follow-up 8.0 ± 3.6 months) were analyzed. Four articles were level IV evidence and one article was level II. Mean MCMS was 56.0 ± 10.3. There were 43 males and 37 females (10 unidentified). Pain VAS significantly improved following lumbar intradiscal PRP injection (69.7 mm to 43.3 mm; p<0.01). Two patients (2.2%) experienced lower extremity paresthesia after treatment. One patient (1.1%) underwent re-injection. No other complications were reported. In conclusion, intradiscal injection of PRP for degenerative discs resulted in statistically significant improvement in VAS with low re-injection and complication rates in this systematic review. It is unclear whether the improvements were clinically significant given the available evidence. The low level of evidence available (level IV) does not allow for valid conclusions regarding efficacy; however, the positive results suggest that further higher-quality studies might be of value.

Augmentation of Meniscal Repair With Platelet-Rich Plasma: A Systematic Review of Comparative Studies

Background:

The effect of platelet-rich plasma (PRP) augmentation for meniscal repair (MR) is unclear, as current evidence is limited to small, mostly nonrandomized studies.

Purpose:

To systematically review the literature to evaluate the efficacy and safety of MR with PRP augmentation.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

A systematic review was performed by searching PubMed, the Cochrane Library, and Embase to identify studies (level of evidence 1-3) that compared the clinical efficacy of MR performed with versus without PRP. The search phrase used was platelet-rich plasma meniscus. Patients were assessed based on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the visual analog scale (VAS) for pain, the Lysholm score, the Knee injury and Osteoarthritis Outcome Score (KOOS), the subjective International Knee Documentation Committee (IKDC) score, and treatment failure.

Results:

We identified 6 studies (2 studies with level 1 evidence; 4 studies with level 3 evidence) that met inclusion criteria, for a total of 309 patients undergoing MR with PRP (mean age, 31.9 years) and 445 patients without PRP augmentation (mean age, 29.6 years). The mean follow-up was 32.8 months (range, 12-72 months). Overall, 17.0% of PRP patients experienced MR failure compared with 22.1% of non-PRP patients. No differences in VAS, Lysholm, or subjective IKDC scores were found between groups except in 1 study, in which postoperative subjective IKDC scores were significantly better in the PRP group (P < .01). Another study found significantly better postoperative WOMAC scores among PRP patients, and 2 studies found significantly better KOOS subscores among PRP patients.

Conclusion:

There are a limited number of high-quality studies comparing outcomes and healing rates between patients undergoing MR with versus without PRP augmentation. Based on the available evidence, patients undergoing MR with PRP augmentation experience similar clinical outcomes at midterm follow-up when compared with conventional MR, and additional studies are needed to determine the efficacy of MR augmented with PRP.

The effects of platelet-rich plasma injection in knee and hip osteoarthritis: a meta-analysis of randomized controlled trials

OBJECTIVE

We conducted this updated meta-analysis to evaluate the effects of PRP in patients with knee or hip OA.

METHOD

PubMed, Embase, and Web of Science were searched to identify randomized controlled trials (RCTs) that compared the efficacy of PRP with other intra-articular injections. The outcomes of interest included Western Ontario and McMaster (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), Visual Analog Scale (VAS), Harris Hip Score (HHS), and International Knee Documentation Committee (IKDC).

RESULTS

Twenty-four RCTs with 21 at knee OA and three at hip OA were included in this meta-analysis. The PRP injections significantly improved the WOMAC score, VAS score, IKDC score, and HHS score as compared with comparators. The WOMAC pain, stiffness, and physical function scores were also significantly better in the PRP group than in the control group. Most of the evaluated parameters that favored PRP were observed in knee OA but not in hip OA, at short-term (at 1, 2, 3, 6, 12 months) but not long-term follow-up (at 18 months), in RCTs with low risk of bias.

CONCLUSIONS

Intra-articular PRP injection provided better effects than other injections for OA patients, especially in knee OA patients, in terms of pain reduction and function improvement at short-term follow-up. Key Points • This updated meta-analysis, based on great sample size and high-quality studies, evaluates the effects of PRP in patients with knee or hip OA. • Intra-articular PRP injection provided better effects than other injections for OA patients. • Most of the evaluated parameters that favored PRP were observed in knee OA at short term (at 1, 2, 3, 6, 12 months).

Reactivating Ovarian Function through Autologous Platelet-Rich Plasma Intraovarian Infusion: Pilot Data on Premature Ovarian Insufficiency, Perimenopausal, Menopausal, and Poor Responder Women

Intraovarian platelet-rich plasma (PRP) infusion was recently introduced in the context of addressing ovarian insufficiency. Reporting on its effectiveness prior to adopting in clinical routine practice is imperative. This study aims to provide pilot data regarding PRP application for ovarian rejuvenation. Four pilot studies were conducted on poor ovarian response (POR), premature ovarian insufficiency (POI), perimenopause, and menopause, respectively. Each pilot study reports on thirty patients, 120 participants were recruited in total. All participants provided written informed consent prior to treatment. Primary outcome measures for the POR pilot study were levels of anti-müllerian hormone (AMH), antral follicle count (AFC) and oocyte yield. For the POI, perimenopausal and menopausal pilot studies primary outcome measures were restoration of menstrual cycle, and Follicle Stimulating Hormone (FSH) levels. A significant improvement on the hormonal profile and the ovarian reserve status was noted, along with improved intracytoplasmic sperm injection (ICSI) cycle performance concerning POR participants. Menstruation recovery was observed in 18 out of 30 POI patients, along with a statistically significant improvement on levels of AMH, FSH, and AFC. Similarly, 13 out of 30 menopausal women positively responded to PRP treatment. Finally, menstruation regularity, improved hormonal levels and AFC were reported for 24 out of 30 perimenopausal women. To conclude, PRP infusion appears to convey promising results in addressing ovarian insufficiency.

Effects of intraovarian injection of autologous platelet rich plasma on ovarian reserve and IVF outcome parameters in women with primary ovarian insufficiency

We aimed to determine whether intraovarian injection of autologous platelet rich plasma (PRP) improves response to ovarian stimulation and in vitro fertilization (IVF) outcome in women with primary ovarian insufficiency (POI). Women (N=311; age 24-40) diagnosed with POI based on ESHRE criteria underwent intraovarian PRP injection. Markers of ovarian reserve, and IVF outcome parameters were followed. PRP treatment resulted in increased antral follicle count (AFC) and serum antimullerian hormone (AMH), while serum follicle stimulating hormone (FSH) did not change significantly. After PRP injection, 23 women (7.4%) conceived spontaneously, 201 (64.8%) developed antral follicle(s) and attempted IVF, and 87 (27.8%) had no antral follicles and therefore did not receive additional treatment. Among the 201 women who attempted IVF, 82 (26.4% of total) developed embryos; 25 of these women preferred to cryopreserve embryos for transfer at a later stage, while 57 underwent embryo transfer resulting in 13 pregnancies (22.8% per transfer, 4% of total). In total, of the 311 women treated with PRP, 25 (8.0%) achieved livebirth/sustained implantation (spontaneously or after IVF), while another 25 (8.0%) cryopreserved embryos. Our findings suggest that in women with POI, intraovarian injection of autologous PRP might be considered as an alternative experimental treatment option.

Advances in the development of gene therapy, noncoding RNA, and exosome-based treatments for tendinopathy

Tendinopathy is a common musculoskeletal disorder characterized by chronic low-grade inflammation and tissue degeneration. Tendons have poor innate healing ability and there is currently no cure for tendinopathy. Studies elucidating mechanisms underlying the pathogenesis of tendinopathy and mechanisms mediating the genesis of tendons during development have provided novel targets and strategies to enhance tendon healing and repair. This review summarizes the current understanding and treatments for tendinopathy. The review also highlights recent advances in gene therapy, the potential of noncoding RNAs, such as microRNAs, and exosomes, which are nanometer-sized extracellular vesicles secreted from cells, for the treatment of tendinopathy.

Platelet-rich plasma promotes recruitment of macrophages in the process of tendon healing

INTRODUCTION

Researchers have investigated the use of platelet-rich plasma (PRP) therapy. However, the mechanisms through which PRP affects tissue repair remain unclear. We hypothesize that PRP promotes tissue repair through not only via direct manner on the local cells but also via indirect manner that encourage the recruitment of reparative cells such as macrophages (MPs), and it depends on the quality of PRP including the concentration of leukocytes. The aim of this study is to elucidate the actions of the MPs in the mechanisms of PRP on tissue repair processes.

METHODS

Leukocyte-rich (LR) PRP and leukocyte-poor (LP) PRP were prepared from 12-week-old C57BL6 mice. Full-thickness defects were created in central third of patellar tendons of 12-week-old C57BL/6 mice for histologic analysis (n = 36) and 12-week-old B6.129P-Cx3cr1tm1Litt/J mice for flow cytometry analysis (n = 108). B6.129P-Cx3cr1tm1Litt/J mouse is GFP-positive only in the MP-linage cells thus MPs recruited to the repair tissue can be distinguished whether it had originated from administrated PRP or recruited from host mouse. Mice were treated either with LR-PRP, LP-PRP, or without PRP (control group). Histological analyses were performed to evaluate the tendon healing using Bonar score as semi-quantitative histological scoring system. Flow cytometric analyses were performed to count the number of GFP-positive cells around repaired patellar tendon. In addition, the ratio of pro-inflammatory MPs (M1)/anti-inflammatory MPs (M2) were analyzed in those GFP-positive cells. The statistical analysis was performed using GraphPad Prism ver6. P values < 0.05 were considered statistically significant.

RESULTS

In LR-PRP and LP-PRP groups, all variables in Bonar score such as cell morphology, cellularity, vascularity, and collagen arrangement were significantly improved in comparison with control group, indicating that both PRPs promote tendon hearing. LP-PRP promoted the tendon healing significantly faster than that of LR-PRP on postoperative day 28 (P < 0.001). LR-PRP enhanced angiogenesis (vascularity: P < 0.001), while LP-PRP improved the collagen arrangement on postoperative day 28 (collagen arrangement: P < 0.01). In other variables such as cell morphology and cellularity score, there were no significant differences between LR-PRP and LP-PRP groups in any time points. Flow cytometric findings showed that recruitment of GFP-positive MPs in the LR and LP-PRP groups were significantly increased from postoperative day 4 compared with control group without PRP treatment (P < 0.001). The majority of GFP-positive MPs were M1 at the initiation of tendon healing phase, and M2 were gradually increased from postoperative day 4. The number of M1 was significantly high both in the LP- and LR-PRP groups (day 4 and 7, p < 0.001), but the number of M2 was high only in the LP-PRP group (day 7 and 14, P < 0.05) when it compared with control group. The M1/M2 ratio on postoperative day 7 was significantly lower in the LP-PRP group than those in the control group (P < 0.05).

CONCLUSIONS

This study demonstrated that PRP enhanced the tendon healing and promoted the recruitment of MPs to the injured tissue. The subtypes of MPs were different depends on the types of PRPs, suggesting that leukocytes in PRP influence the effect of PRP therapy.

Comparison of Two Anticoagulants for Pain Associated with Platelet-Rich Plasma Injections

BACKGROUND AND AIM

Platelet-rich plasma (PRP) has long been used in skin rejuvenation and hair loss treatment. Some patients require multiple intradermal injections into the face and scalp, and the way in which these patients process and experience pain differs, depending on the patient. Minimizing pain and discomfort during nonsurgical procedures is essential for patient satisfaction. In our experience, the use of acid citrate dextrose-A (ACD-A) as an anticoagulant caused more patient discomfort than did sodium citrate (Na-citrate) among patients who underwent facial rejuvenation with PRP. The aim of the present study was to evaluate patient-related discomfort in PRP sessions using two different anticoagulants.

MATERIALS AND METHODS

This clinical trial included 10 patients who received facial PRP injections for facial rejuvenation and 10 patients who received PRP injections in their scalps for hair loss. On the application area, half the surface was treated with Na-citrate PRP injections, and the other half was treated with the same amount of ACD-A PRP injections. Neither the doctors who applied the treatment nor the patients were given information about which anticoagulant was used in each area. Immediately after the procedure, the patients were asked to score their pain on each side of the application area on a scale of 1-10 using a visual analog scale (VAS).

RESULTS

PRP injections using Na-citrate as an anticoagulant caused less discomfort on both the face and scalp as compared with that of ACD-A. The outcome was statistically significant.

CONCLUSION

Anticoagulants used in PRP preparation affected patients' pain perceptions during the injections. The sensation of pain with PRP prepared with Na-citrate as an anticoagulant was lower than that of PRP prepared with ACD-A. Further studies are required to evaluate the correlation between anticoagulants used for PRP preparation and pain feelings during injections.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

The Role of Biologic Agents in the Non-operative Management of Elbow Ulnar Collateral Ligament Injuries

PURPOSE OF REVIEW

Injuries to the elbow ulnar collateral ligament (UCL) are especially common in the overhead throwing athlete. Despite preventative measures, these injuries are occurring at increasing rates in athletes of all levels. UCL reconstruction techniques generally require a prolonged recovery period and introduce the potential for intraoperative complications prompting investigations into more conservative treatment measures based on specific patient and injury characteristics. The purpose of this review is to describe the current literature regarding the use of biologic augmentation in the management of UCL injuries. Specifically, this review will focus on the basic science background and clinical investigations pertaining to biologic augmentation utilizing platelet-rich plasma (PRP) and autologous stem cells.

RECENT FINDINGS

Despite some evidence supporting the use of PRP therapy in patients with partial UCL tears, there is no current consensus regarding its true efficacy. Similarly, due to a lack of clinical investigations, no consensus exists regarding the utilization of autologous stem cell treatments in the management of UCL injuries. Management of UCL injuries ranges from non-operative treatment with focused physical therapy protocols to operative reconstruction. The use of biologic augmentation in these injuries continues to be investigated in the orthopedic community. Currently, no consensus exists regarding the efficacy of either PRP or autologous stem cells and further research is needed to further define the appropriate role of these treatments in the management of UCL injuries.

Cytokine and Growth Factor Delivery from Implanted Platelet-Rich Fibrin Enhances Rabbit Achilles Tendon Healing

Tendons are hypocellular and hypovascular tissues, and thus, their natural healing capacity is low. In this study, we sought to evaluate the efficacy of platelet-rich fibrin (PRF) to serve as a bioactive scaffold in promoting the healing of rabbit Achilles tendon injury. For in vitro study, the essence portion of PRF was determined through bioluminescent assay. Furthermore, we analyzed the time-sequential cytokines-release kinetics of PRF and evaluated their effects on tenocytes proliferation and tenogenic gene expressions. In animal study, the rabbit Achilles tendon defect was left untreated or implanted with normal/heat-denatured PRF scaffolds. Six weeks postoperatively, the specimens were evaluated through sonographic imaging and histological analysis. The results revealed significantly more activated platelets on bottom half of the PRF scaffold. Cytokine concentrations released from PRF could be detected from the first hour to six days. For the in vitro study, PRF enhanced cell viability and collagen I, collagen III, tenomodulin, and tenascin gene expression compared to the standard culture medium. For in vivo study, sonographic images revealed significantly better tendon healing in the PRF group in terms of tissue echogenicity and homogeneity. The histological analysis showed that the healing tissues in the PRF group had more organized collagen fiber, less vascularity, and minimal cartilage formation. In conclusion, bioactive PRF promotes in vitro tenocytes viability and tenogenic phenotypic differentiation. Administration of a PRF scaffold at the tendon defect promotes tissue healing as evidenced by imaging and histological outcomes.

Growth Factor Delivery to a Cartilage-Cartilage Interface Using Platelet-Rich Concentrates on a Hyaluronic Acid Scaffold

PURPOSE

To determine whether (1) human leukocyte-platelet-rich plasma (L-PRP) or (2) leukocyte-platelet-rich fibrin (L-PRF) delivered on a hyaluronic acid (HA) scaffold at a bovine chondral defect, a simulated cartilage tear interface, in vitro would improve tissue formation based on biomechanical, histologic, and biochemical measures.

METHODS

L-PRF and L-PRP were prepared from 3 healthy volunteer donors and delivered in conjunction with HA scaffolds to defects created in full-thickness bovine cartilage plugs harvested from bovine femoral condyle and trochlea. Specimens were cultured in vitro for up to 42 days. Treatment groups included an HA scaffold alone and scaffolds containing L-PRF or L-PRP. Cartilage repair was assessed using biomechanical testing, histology, DNA quantification, and measurement of sulfated glycosaminoglycan and collagen content at 28 and 42 days.

RESULTS

L-PRF elicited the greatest degree of defect filling and improvement in other histologic measures. L-PRF-treated specimens also had the greatest cellularity when compared with L-PRP and control at day 28 (560.4 μg vs 191.4 μg vs 124.2 μg, P = .15); at day 48, there remained a difference, although not significant, between L-PRF versus L-PRP (761.1 μg vs 589.3 μg, P = .219) . L-PRF had greater collagen deposition when compared with L-PRP at day 42 (40.1 μg vs 16.3 μg, P < .0001). L-PRF had significantly greater maximum interfacial strength compared with the control at day 42 (10.92 N vs 0.66 N, P = .015) but had no significant difference compared with L-PRP (10.92 N vs 6.58 N, P = .536). L-PRP facilitated a greater amount of sulfated glycosaminoglycan production at day 42 when compared with L-PRF (15.9 μg vs 4.3 μg, P = .009).

CONCLUSIONS

Delivery of leukocyte-rich platelet concentrates in conjunction with a HA scaffold may allow for improvements in cartilage healing through different pathways. L-PRF was not superior to L-PRP in its biomechanical strength, suggesting that both treatments may be effective in improving biomechanical strength of healing cartilage through different pathways.

CLINICAL RELEVANCE

The delivery of platelet-rich concentrates in conjunction HA scaffolds may augment healing cartilaginous injuries.

Injection therapies for patellar tendinopathy

Patellar tendinopathy, or jumper's knee is a common musculoskeletal condition characterized by progressive activity-related pain on the anterior aspect of the knee and tenderness on the patellar tendon. A conservative method is often the first choice of treatment, which can include anti-inflammatory medication, injection therapies, physiotherapy, eccentric exercises, extra corporeal shock wave therapy, orthosis, etc. Although there are several treatment options available, the management of patellar tendinopathy is still controversial. The literature reveals many different injection methods are being used by clinicians for the treatment of patellar tendinopathy. Platelet rich plasma, corticosteroids, autologous blood, and aprotinin are the most commonly used injection treatments. Injection therapies give promising results in the management of Patellar tendinopathy. However, due to low quality research and variation in the protocol and population it is difficult to provide a firm conclusion on its effectiveness. More high-quality clinical studies are recommended to determine the effectiveness of injections and at which stage of Patellar tendinopathy they are the most effective. This review can provide insight to clinicians involved in the management of this condition.

Bony Ingrowth of Coil-Type Open-Architecture Anchors Compared With Screw-Type PEEK Anchors for the Medial Row in Rotator Cuff Repair: A Randomized Controlled Trial

PURPOSE

To evaluate outcomes of screw-type and coil-type open-architecture suture anchors with respect to bony ingrowth, release of biological markers, and patient-reported outcome measures when used in rotator cuff repair (RCR).

METHODS

Forty patients undergoing arthroscopic RCR for full-thickness rotator cuff tears were enrolled and prospectively randomized to receive a screw-type (19 patients) or coil-type (21 patients) suture anchor for the medial row during repair. All repairs used a transosseous-equivalent configuration with footprint anchors laterally. Marrow elements released during surgery were evaluated for 9 cytokine markers (insulin-like growth factor 1, fibroblast growth factor 2, bone morphogenetic proteins 7 and 2, platelet-derived growth factors AA and BB, epidermal growth factor, transforming growth factor beta1, and vascular endothelial growth factor). Postoperative computed tomography scans were performed at 6 months. Range of motion, strength, and validated patient-reported outcome measures (Simple Shoulder Test, Single Assessment Numeric Evaluation, visual analog scale, and American Shoulder and Elbow Surgeons scores) were gathered before the operation and at 6 months and 1 year postoperatively.

RESULTS

Bone mineral density surrounding the coil-type anchor was significantly greater than that surrounding the screw-type anchor (P = .005). Bone mineral density values within the coil-type and screw-type anchors were comparable (P = .527); however, a larger amount of total bone mineral mass (in milligrams) was shown within the coil-type anchor owing to its larger volume (P < .01). Marrow elements released at the repair site were similar between groups (P > .05). Postoperatively, no statistically significant difference was found between groups for clinical outcome measures at 6 months or 1 year. Retear and complication rates were similar between groups (P > .05).

CONCLUSIONS

Both the coil-type and screw-type anchors can be reliably used for RCR and produce similar clinical outcomes. The coil-type anchor resulted in superior bony growth surrounding the anchor and a larger total bone mineral mass within the anchor owing to its larger volume.

LEVEL OF EVIDENCE

Level II, randomized prospective comparative study.

Effect of Storage Conditions and Activation on Growth Factor Concentration in Platelet-Rich Plasma

This study aimed to evaluate growth factor concentration in platelet-rich plasma (PRP) (leukocyte-rich PRP) based on storage temperature, duration of storage, and method of activation. PRP samples were stored at 24℃ (room temperature group), 4℃ (refrigerator group), and -70℃ (deep-freezer group). In each temperature, four aliquots were prepared based on the time of analysis (immediately, 1, 3, and 7 days after preparation). After storage, concentrations of platelet-derived growth factor-AA (PDGF-AA), transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), insulin-like growth factor-1 (IGF-1), and fibroblast growth factor-basic (FGF-B) were assessed with/without activation using Quantikine colorimetric sandwich immunoassay kits. PRP was activated with 10% Triton-X for PDGF-AA, VEGF, FGF-B, IGF-1 measurement and sonication for TGF-β1 measurement. Without activation, PDGF-AA concentration was highest on day 7 in the room temperature group. With activation, the concentration of PDGF-AA was constant over the observation period at all temperatures. Without activation, the TGF-β1 concentration remained negligible over the observation period at all temperatures. However, with activation, TGF-β1 gradually increased to its highest concentration on day 7 at all temperatures. Over the observation period, VEGF and IGF-1 concentrations were constant with and without activation at all temperatures. Without activation, FGF-B concentration increased, with the highest concentration observed on day 7 in the deep-freezer group. With activation, FGF-B concentration decreased after day 1 in the room temperature group. Growth factor concentration in PRP differed significantly based on storage temperature, duration of storage, and method of activation. Appropriate storage conditions and activation are important to optimize its effects on desired clinical outcomes. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:777-784, 2020.

Addition of Platelet-Rich Plasma to Silk Fibroin Hydrogel Bioprinting for Cartilage Regeneration

The recent advent of 3D bioprinting of biopolymers provides a novel method for fabrication of tissue-engineered scaffolds and also offers a potentially promising avenue in cartilage regeneration. Silk fibroin (SF) is one of the most popular biopolymers used for 3D bioprinting, but further application of SF is hindered by its limited biological activities. Incorporation of growth factors (GFs) has been identified as a solution to improve biological function. Platelet-rich plasma (PRP) is an autologous resource of GFs, which has been widely used in clinic. In this study, we have developed SF-based bioinks incorporated with different concentrations of PRP (12.5%, 25%, and 50%; vol/vol). Release kinetic studies show that SF-PRP bioinks could achieve controlled release of GFs. Subsequently, SF-PRP bioinks were successfully fabricated into scaffolds by bioprinting. Our results revealed that SF-PRP scaffolds possessed proper internal pore structure, good biomechanical properties, and a suitable degradation rate for cartilage regeneration. Live/dead staining showed that 3D, printed SF-PRP scaffolds were biocompatible. Moreover, in vitro studies revealed that tissue-engineered cartilage from the SF-PRP group exhibited improved qualities compared with the pure SF controls, according to histological and immunohistochemical findings. Biochemical evaluations confirmed that SF-PRP (50% PRP, v/v) scaffolds allowed the largest increases in collagen and glycosaminoglycan concentrations, when compared with the pure SF group. These findings suggest that 3D, printed SF-PRP scaffolds could be potential candidates for cartilage tissue engineering. Impact statement Three-dimensional bioprinting of silk fibroin (SF) hydrogel as bioinks is a promising strategy for cartilage tissue engineering, but it lacks biological activities, which favors proliferation of seeded cells and secretion of the extracellular matrix. In this study, we have successfully added platelet-rich plasma (PRP) into SF-based bioinks as an autologous source of growth factors. The 3D, printed SF-PRP scaffold showed an enhanced biological property, thus aiding in potential future development of novel cartilage tissue engineering applications.

Investigation of the effects of thrombocyte-rich plasma, systemic ozone and hyperbaric oxygen treatment on intraoral wound healing in rats: experimental study

OBJECTIVE

In this study, it was aimed to evaluate and compare biochemical and histopathological effects of platelet-rich plasma (PRP), ozone and hyperbaric oxygen (HBO) on wound healing which was formed experimentally in oral cavity of rats.

MATERIALS AND METHODS

In this study, thirty-six Wistar Hannover rats with weight of 250-350 g, fed with standard feeds, were anesthetized to create intraoral wound on the hard palate. Rats were divided into four groups as the following: control group, PRP, HBO and Ozone groups. 0.1 ml of PRP was injected on the wound edges of each rat in the PRP group on days 1, 3 and 7. Each rat in the ozone group was systemically injected with 2.3-3.0 ml ozone gas on the 1st, 3rd and 7th days. The wounds of the rats in the control group were not performed anything. The rats in the HBO group were placed in the HBO pressure chamber and were treated with one session (2 h for each session) of 100% oxygen each day for 7 days. Rats in all groups were killed on the 15th day and the hard palates were excised for histopathological examination. Inflammation severity, neovascularization, fibroblast proliferation, collagen density and epithelization were evaluated.

RESULTS

The rate of intense wound closure (epithelialization intensity) was significantly higher in all the three treatment groups, the PRP group was the highest, than in the control group (p < 0.05). Fibroblast proliferation level was higher in PRP group (p < 0.05), followed by ozone, HBO and control groups, respectively. Histologically, inflammation was significantly higher in the control group than the treatment groups (p < 0.05). For the treatment groups; it was lowest in the PRP group, followed by the ozone and HBO groups, respectively. The rates of angiogenesis and collagenization were significantly higher in all the three treatment groups, the PRP group was the highest, than in the control group (p < 0.05). In this study, no significance difference was found between the groups in terms of blood glucose levels (p = 0.21).

CONCLUSION

In this study, all three treatment modalities were found to be effective in wound healing, and PRP was found to be more effective than the others.

Effects of autologous platelet-rich plasma injections on facial skin rejuvenation

Autologous serum platelet-rich plasma (PRP) has been used to rejuvenate wrinkled and aged skin for years; however, the molecular mechanism for the positive effects of PRP on the skin remains unclear. The present study aimed to clarify the potential molecular mechanisms for the role of PRP in wrinkled and aged skin rejuvenation, and provide evidence for future clinical applications. A total of 30 healthy females were recruited for PRP treatment and signed informed consent was obtained. A total of 3 autologous PRP injections were administered to each patient with 15-day intervals between injections. The effects of PRP injections were evaluated using the VISIA^® Complexion Analysis System and skin computed tomography. A human organotypic skin model was established and treated with PBS or PRP before ultraviolet (UV)-B light (10 mJ/cm²) irradiation. The distribution of the epidermal structure and dermal fibers were analyzed by hematoxylin and eosin and Masson's trichome staining. Expression of matrix metalloproteinase-1 (MMP-1), tyrosinase, fibrillin and tropoelastin was detected by reverse transcription-quantitative PCR, western blotting and immunofluorescence. The present results showed that PRP treatment improved skin quality in the participants. In addition, the VISIA^® results showed that wrinkles, texture and pores were decreased in the PRP groups compared with the PBS treatment. The in vitro study demonstrated that PRP treatment ameliorated photoaging by inhibiting UV-B-induced MMP-1 and tyrosinase upregulation, and by inducing fibrillin and tropoelastin expression that was downregulated by UV-B. Collectively, it was demonstrated that PRP treatment ameliorated skin photoaging through regulation of MMP-1, tyrosinase, fibrillin and tropoelastin expression.

Platelet Concentrates in Musculoskeletal Medicine

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