Characterization of distinct microbiota associated with androgenetic alopecia patients treated and untreated with platelet-rich plasma(PRP)

Background:Androgenic alopecia(AGA)is the most common type of hair loss in men,and there are many studies on the treatment of hair loss by platelet-rich plasma(PRP).The human scalp contains a huge microbiome,but its role in the process of hair loss remains unclear,and the relationship between PRP and the microbiome needs further study.Therefore,the purpose of this study was to investigate the effect of PRP treatment on scalp microbiota composition.Methods:We performed PRP treatment on 14 patients with AGA,observed their clinical efficacy,and collected scalp swab samples before and after treatment.The scalp microflora of AGA patients before and after treatment was characterized by amplifying the V3-V4 region of the 16 s RNA gene and sequencing for bacterial identification.Results:The results showed that PRP was effective in the treatment of AGA patients,and the hair growth increased significantly.The results of relative abundance analysis of microbiota showed that after treatment,g_Cutibacterium increased and g_Staphylococcus decreased,which played a stable role in scalp microbiota.In addition,g_Lawsonella decreased,indicating that the scalp oil production decreased after treatment.Conclusions:The findings suggest that PRP may play a role in treating AGA through scalp microbiome rebalancing.

Efficacy and safety of platelet-rich plasma intracavernous injection for patients with erectile dysfunction:A systematic review,meta-analysis,and meta-regression

ObjectiveIntracavernous injection might be offered to patients with erectile dysfunction (ED) who did not respond to the first-line oral treatment. Platelet-rich plasma (PRP) might offer improvement in erectile function since it contains numerous growth factors. This study aimed to evaluate the efficacy and safety of PRP intracavernous injection for patients with ED.MethodsWe conducted relevant literature searches on Cochrane Library, Medline, Scopus, and ClinicalTrials.gov databases using specific keywords. The results of continuous variables were pooled into the mean difference (MD) and dichotomous variables into the odds ratio along with 95% confidence interval (95% CI).ResultsA total of six studies were included. Our pooled analysis revealed that PRP intracavernous injection was associated with a significant increase in the erectile function domain of the International Index of Erectile Function at 1 month (MD 3.47 [95% CI 2.62–4.32], p<0.00001, I^(2)=7%), 3 months (MD 3.19 [95% CI 2.25–4.12], p<0.00001, I^(2)=0%), and 6 months (MD 3.21 [95% CI 2.30–4.13], p<0.00001, I^(2)=0%) after the intervention when compared with baseline values. PRP was also superior to a placebo in terms of improvement in erectile function domain of the International Index of Erectile Function score at 1 month (MD 2.83, p<0.00001), 3 months (MD 2.87, p<0.00001), and 6 months (MD 3.20, p<0.00001) post-intervention. The adverse events from PRP injection were only mild without any serious adverse events.ConclusionPRP intracavernous injection may offer benefits in improving erectile function in patients with ED with a relatively good safety profile.

Efficacy of intraovarian autologous platelet-rich plasma administration in women with low ovarian reserve: A systematic review and meta-analysis

Objective:To conduct a systematic examination and meta-analysis of the most reliable data from experimental studies evaluating the efficacy of autologous platelet-rich plasma(PRP)on low ovarian reserve.Methods:A comprehensive search was performed utilizing pertinent search terms across electronic databases,including PubMed,Cochrane,and Google Scholar.We included studies that assigned infertile women with low ovarian reserve in experimental studies.Ovarian reserve parameters were measured before and after PRP injection into ovaries.The data of each study was retrieved and subsequently compiled.Results:Of 301 articles collected and reviewed,six studies were finally included in the meta-analysis.Following PRP injection,infertile women showed a non-significant increase in anti-Mullerian hormone(AMH)level(MD=0.10;95%CI-0.04,0.23),a significant increase in antral follicular count(AFC)(MD=1.88;95%CI 0.47,3.29),and a non-significant reduction in follicle-stimulating hormone(FSH)level(MD=-0.22;95%CI-8.32,7.87).Conclusions:Autologous PRP may increase AFC,but not AMH.Although it is found beneficial in enhancing ovarian reserve(AFC),further research with strong evidence is still required.

Platelet-rich plasma treatment for chronic wounds:A case report and literature review

BACKGROUND Wound healing is a complicated process that can be heavily influenced by patient comorbidities,in some cases leading to a chronic non-healing wound.Evidence presented in the medical literature supporting the clinical use of autologous platelet-rich plasma(PRP)in treatment of such wounds is becoming increasingly compelling.Mechanisms involved include complex interactions between the patient’s thrombocytes,cytokines,and growth factors.CASE SUMMARY We present a case of a 72-year-old male patient with a long-standing chronic wound and multiple comorbidities.Over the course of more than 7 months,the patient was unsuccessfully treated with all routinely used measures,including different dressing approaches.Multiple antibiotic regimens were administered for wound infection,with repeated evaluation of microbiological swab results.Finally,after three PRP applications,the wound showed clinical improvement with complete restitution of the epithelial layer of the skin.CONCLUSION PRP treatment may be beneficial to reduce healing time in chronic wounds.

Adenylate cyclase activates the cAMP signalling pathway to enhance platelet-rich plasma-treated Achilles tendon disease,a theoretical bioinformatics-based study

The effectiveness of platelet-rich plasma(PRP)for the treatment of Achilles tendon disorders still needs to be evaluated through a series of prospective studies,but genomic analysis can reveal the existence of complementary PRP treatment options.Based on the 96 platelet activation-related genes in the Kyoto Encyclopedia of Genes and Genomes(KEGG)database,we performed Gene Ontology functional enrichment analysis and KEGG enrichment analysis,pathway correlation analysis,and enrichment mapping to determine the enrichment results of the gene set enrichment analysis and found that the cAMP signalling pathway may be the key to enhancing the effectiveness of PRP treatment.The cAMP signalling pathway interacts with the Rap1 signalling pathway and cGMPPKG signalling pathway to mediate the entire pathophy-siological process of Achilles tendon disease.Moreover,ADCY1-9 may be the key to the activation of the cAMP signalling network.Further based on the data in the Gene Expression Omnibus database,it was found that ADCY4 and ADCY7 may be the players that play a major role,associated with the STAT4-ADCY4-LAMA5 axis and the GRbeta-ADCY7-SEMA3C axis,which is expected to be a complementary target for enhancing the efficacy of PRP in the treatment of Achilles tendon disease.

Platelet-rich plasma for de Quervain’s tenosynovitis: A systematic review and meta-analysis

BACKGROUND Platelet-rich plasma(PRP)injection is used as an alternative non-operative management for de Quervain’s tenosynovitis(DQT)to regenerate tendon healing.AIM To assess and conclude the research-based study systematically to analyse the efficacy of PRP on DQT.METHODS This systematic review used the Cochrane Handbook for Systematic Reviews and the guideline of preferred reporting items for systematic review and metaanalysis.A systematic literature search was applied to 11 databases.The authors assessed the study quality and risk of bias of each included study.Results of the meta-analysis were presented using mean difference(MD)/standardized mean difference(SMD)and 95%condence interval(CI).RESULTS The authors evaluated 275 studies found in the literature search;12 studies met the criteria for this review,and then the study quality and risk of bias were assessed.Pooled analysis of data from two studies involving 194 subjects with DQT showed that,compared with conservative treatment,PRP injection was associated with a greater reduction in visual analog scale pain in one month and six months after treatment(MD:-0.67,P value<0.00001;MD:-1.16,P value<0.00001)and the increase of Mayo’s wrist score in one month and six months after treatment(SMD:3.72,P value<0.00001;SMD:4.44,P value<0.00001).CONCLUSION PRP can be used as an alternative non-operative treatment for DQT due to the tissue regenerative effect of PRP.

Effectiveness of a Single High Dose of Platelet-Rich Plasma (PRP) Injection Over Corticosteroid and Hyaluronic Acid Injections on Osteoarthritis, Chronic Tendinitis and Tennis Elbow Treatment

Background: Corticosteroid, hyaluronic acid (HA) injections and Anti-inflammatory agents are considered as non-invasive treatments for knee osteoarthritis (OA), Chronic Tendinitis (CT) and Tennis elbow (TE) that are supposed to provide symptomatic relief and to help surgical delay intervention. Platelet rich plasma (PRP) is a biological component shown to be beneficial for different orthopedic dysfunctionalities treatment. The presence of GFs in PRPs such as transforming growth factor-β, insulin-like growth factor 1co-stimulate the mesenchymal stem cells and fibroblasts secretions and promotes the fibrin matrix formation which effectively drive the healing process, induces regenerative response and lead to the damage structure repair in orthopedics trauma. Methods: Three groups of a total of 30 patients presenting OA, CT and TE diagnosis, non-responding to corticosteroid, HA and non-steroid anti-inflammatory treatments were randomized to undergo one intra-articular injections of single high dose of PRP. The efficacy of Intra-articular PRP Injections was evaluated before the injection and one month after. The efficiency assessment score was based on [1] Knee injury and Osteoarthritis Outcome Score, [2] Physical Function Short Form (KOOS-PS) Arabic (KSA) version LK 1.0, [3] HOOS-Physical Function Short form (HOOS-PS), and [4] Macdermid patient-rated Tennis Elbow. Results: A significant reduction of pain and a marked improvement in movements was observed in the 3 patient’s groups, PRP-injected patients showed significantly higher values compared with baseline: (p < 0.005 vs baseline), improve functional status and reduce clearly the articular dysfunctions over the time. In our study, single High dose injection of PRP provided an overall superior clinical improvement compared with HA and corticosteroid treatments over the time and the different follow-up checkpoints of the study.

Vacuum Assisted Closure (VAC) and Platelet-Rich Plasma (PRP): A Successful Combination in a Challenging Case of Gastroschisis

Giant gastroschisis could be a surgical challenge concerning the abdominal wall reconstruction. Many techniques have been described for both primary or staged closure but sometimes neither of them is succesful in all patients. We are presenting the combined use of Vacuum Assisted Closure (VAC) and Platelet-Rich Plasma (PRP) to improve the result in this difficult case. The use of VAC device is a well known procedure in the treatment of adult difficult wounds closure. It consists of a sponge applied directly on the abdominal wall defect, covered with a transparent dressing and connected to a controlled continuous negative pressure system [1]. Platelet-rich plasma (PRP) is an autologous concentration of human platelets in a small volume of plasma. Due to this combination it provides multiple growth and healing factors actively secreted by platelets which have been shown to begin and accelerate wound healing [2] [3]. The association between VAC and PRP was effective in the shrinkage and reduction of the abdominal defect. Fifteen months after the removal of the VAC device the fascia appears competent with a cutaneus scar that will need a plastic correction in the future. The VAC should be considered as a helpful and effective device in case of complicated giant gastroschisis or omphalocele when traditional treatment is not sufficient.

Application of platelet-rich plasma with stem cells in bone and periodontal tissue engineering

Presently, there is a high paucity of bone grafts in the United States and worldwide. Regenerating bone is of prime concern due to the current demand of bone grafts and the increasing number of diseases causing bone loss. Autogenous bone is the present gold standard of bone regeneration. However, disadvantages like donor site morbidity and its decreased availability limit its use. Even allografts and synthetic grafting materials have their own limitations. As certain specific stem cells can be directed to differentiate into an osteoblastic lineage in the presence of growth factors(GFs), it makes stem cells the ideal agents for bone regeneration.Furthermore, platelet-rich plasma(PRP), which can be easily isolated from whole blood, is often used for bone regeneration, wound healing and bone defect repair. When stem cells are combined with PRP in the presence of GFs, they are able to promote osteogenesis. This review provides in-depth knowledge regarding the use of stem cells and PRP in vitro, in vivo and their application in clinical studies in the future.

Platelet-rich plasma for regeneration of neural feedback pathways around dental implants: a concise review and outlook on future possibilities

Along with the development of new materials, advanced medical imaging and surgical techniques, osseointegrated dental implants are considered a successful and constantly evolving treatment modality for the replacement of missing teeth in patients with complete or partial edentulism. The importance of restoring the peripheral neural feedback pathway and thus repairing the lack of periodontal rnechanoreceptors after tooth extraction has been highlighted in the literature. Nevertheless, regenerating the nerve fibers and reconstructing the neural feedback pathways around osseointegrated implants remain a challenge. Recent studies have provided evidence that platelet-rich plasma （PRP） therapy is a promising treatment for musculoskeletal injuries. Because of its high biological safety, convenience and usability, PRP therapy has gradually gained popularity in the clinical field Although much remains to be learned, the growth factors from PRP might play key roles in peripheral nerve repair mechanisms. This review presents known growth factors contributing to the biological efficacy of PRP and illustrates basic and （pre-）clinical evidence regarding the use of PRP and its relevant products in peripheral nerve regeneration. In addition, the potential of local application of PRP for structural and functional recovery of iniured peripheral nerves around dental implants is discussed.

Platelet-rich plasma gel in combination with Schwann cells for repair of sciatic nerve injury

Bone marrow mesenchymal stem cells were isolated from New Zealand white rabbits, culture-expanded and differentiated into Schwann cell-like cells. Autologous platelet-dch plasma and Schwann cell-like cells were mixed in suspension at a density of 1 x 106 cells/mL, prior to introduction into a poly （lactic-co-glycolic acid） conduit. Fabricated tissue-engineered nerves were implanted into rabbits to bridge 10 mm sciatic nerve defects （platelet-rich plasma group）. Controls were established using fibrin as the seeding matrix for Schwann cell-like cells at identical density to construct tissue-engineered nerves （fibrin group）. Twelve weeks after implantation, toluidine blue staining and scanning electron microscopy were used to demonstrate an increase in the number of regenerating nerve fibers and thickness of the myelin sheath in the platelet-rich plasma group compared with the fibrin group. Fluoro-gold retrograde labeling revealed that the number of Fluoro-gold-positive neurons in the dorsal root ganglion and the spinal cord anterior horn was greater in the platelet-rich plasma group than in the fibrin group. Electrophysiological examination confirmed that compound muscle action potential and nerve conduction velocity were superior in the platelet-rich plasma group compared with the fibrin group. These results indicate that autologous platelet-rich plasma gel can effectively serve as a seeding matrix for Schwann cell-like cells to construct tissue-engineered nerves to promote perJpheral nerve regeneration.

Establishing proof of concept:Platelet-rich plasma and bone marrow aspirate concentrate may improve cartilage repair following surgical treatment for osteochondral lesions of the talus

Osteochondral lesions of the talus are common injuries in the athletic patient. They present a challenging clinical problem as cartilage has a poor potential for healing. Current surgical treatments consist of reparative(microfracture) or replacement(autologous osteochondral graft) strategies and demonstrate good clinical outcomes at the short and medium term follow-up. Radiological findings and second-look arthroscopy however, indicate possible poor cartilage repair with evidence of fibrous infill and fissuring of the regenerative tissue following microfracture. Longer-term follow-up echoes these findings as it demonstrates a decline in clinical outcome. The nature of the cartilage repair that occurs for an osteochondral graft to become integrated with the native surround tissue is also of concern. Studies have shown evidence of poor cartilage integration,with chondrocyte death at the periphery of the graft, possibly causing cyst formation due to synovial fluid ingress. Biological adjuncts, in the form of platelet-rich plasma(PRP) and bone marrow aspirate concentrate(BMAC), have been investigated with regard to their potential in improving cartilage repair in both in vitro and in vitro settings. The in vitro literature indicates that these biological adjuncts may increase chondrocyte proliferation as well as synthetic capability, while limiting the catabolic effects of an inflammatory joint environment. These findings have been extrapolated to in vitro animal models, with results showing that both PRP and BMAC improve cartilage repair. The basic science literature therefore establishes the proof of concept that biological adjuncts may improve cartilage repair when used in conjunction with reparative and replacement treatment strategies for osteochondral lesions of the talus.

Single-and double-dose of platelet-rich plasma versus hyaluronic acid for treatment of knee osteoarthritis: A randomized controlled trial

BACKGROUND Platelet-rich plasma(PRP)and hyaluronic acid have been shown to be useful in the treatment of knee osteoarthritis.However,investigations comparing the efficacy of these two drugs together are insufficient.AIM To compare the outcomes of PRP vs hyaluronic acid injections in three groups of patients with bilateral knee osteoarthritis.METHODS This randomized controlled trial study involved 95 patients.Thirty-one subjects received a single injection of PRP(group PRP-1),33 subjects received two injections of PRP at an interval of 3 wk(group PRP-2)and 31 subjects received three injections of hyaluronic acid at 1-wk intervals(group hyaluronic acid).The patients were investigated prospectively at the enrollment and at 4-,8-and 12-wk follow-up with the Western Ontario and McMaster Universities Arthritis Index(WOMAC)and Visual Analogue Scale questionnaires.RESULTS Percentages of patients experiencing at least a 30%decrease in the total score for the WOMAC pain subscale from baseline to wk 12 of the intervention were 86%,100%and 0%in the groups PRP-1,PRP-2 and hyaluronic acid,respectively(P<0.001).The mean total WOMAC scores for groups PRP-1,PRP-2 and hyaluronic acid at baseline were 63.71,61.57 and 63.11,respectively.The WOMAC scores were significantly improved at final follow-up to 42.5,35.32 and 57.26,respectively.The highest efficacy of PRP was observed in both groups at wk 4 with about 50%decrease in the symptoms compared with about 25%decrease for hyaluronic acid.Group PRP-2 had higher efficacy than group PRP-1.No major adverse effects were found during the study.CONCLUSION PRP is a safe and efficient therapeutic option for treatment of knee osteoarthritis.It was demonstrated to be significantly better than hyaluronic acid.We also found that the efficacy of PRP increases after multiple injections.

Platelet-rich plasma:the role in neural repair

The efficacy of platelet-rich plasma（PRP）to promote tissue regeneration has been largely confirmed in several clinical settings,such as in human maxillo-facial（Froum et al.,2002）,heart（Vu et al.,2015）and orthopaedic surgery（Zhang and Wang,2010）.Up to date.

Platelet-rich plasma promotes peripheral nerve regeneration after sciatic nerve injury

The effect of platelet-rich plasma on nerve regeneration remains controversial.In this study,we established a rabbit model of sciatic nerve small-gap defects with preserved epineurium and then filled the gaps with platelet-rich plasma.Twenty-eight rabbits were divided into the following groups(7 rabbits/group):model,low-concentrati on PRP(2.5-3.5-fold concentration of whole blood platelets),medium-concentration PRP(4.5-6.5-fold concentration of whole blood platelets),and high-concentration PRP(7.5-8.5-fold concentration of whole blood platelets).Electrophysiological and histomorphometrical assessments and proteomics analysis we re used to evaluate regeneration of the sciatic nerve.Our results showed that platelet-rich plasma containing 4.5-6.5-and 7.5-8.5-fold concentrations of whole blood platelets promoted repair of sciatic nerve injury.Proteomics analysis was performed to investigate the possible mechanism by which platelet-rich plasma promoted nerve regeneration.Proteomics analysis showed that after sciatic nerve injury,platelet-rich plasma increased the expression of integrin subunitβ-8(ITGB8),which participates in angiogenesis,and differentially expressed proteins were mainly enriched in focal adhesion pathways.Additionally,two key proteins,ribosomal protein S27 a(RSP27 a)and ubiquilin 1(UBQLN1),which were selected after protein-protein interaction analysis,are involved in the regulation of ubiquitin levels in vivo.These data suggest that platelet-rich plasma promotes peripheral nerve regeneration after sciatic nerve injury by affecting angiogenesis and intracellular ubiquitin levels.

Single injection of platelet-rich plasma as a novel treatment of carpal tunnel syndrome

Both in vitro and in vivo experiments have confirmed that platelet-rich plasma has therapeutic effects on many neuropathies, but its effects on carpal tunnel syndrome remain poorly understood. We aimed to investigate whether single injection of platelet-rich plasma can improve the clinical symptoms of carpal tunnel syndrome. Fourteen patients presenting with median nerve injury who had suffered from mild carpal tunnel syndrome for over 3 months were included in this study. Under ultrasound guidance, 1-2 m L of platelet-rich plasma was injected into the region around the median nerve at the proximal edge of the carpal tunnel. At 1 month after single injection of platelet-rich plasma, Visual Analogue Scale results showed that pain almost disappeared in eight patients and it was obviously alleviated in three patients. Simultaneously, the disabilities of the arm, shoulder and hand questionnaire showed that upper limb function was obviously improved. In addition, no ultrasonographic manifestation of the carpal tunnel syndrome was found in five patients during ultrasonographic measurement of the width of the median nerve. During 3-month follow-up, the pain was not greatly alleviated in three patients. These findings show very encouraging mid-term outcomes regarding use of platelet-rich plasma for the treatment of carpal tunnel syndrome.

Platelet-rich plasma,an adjuvant biological therapy to assist peripheral nerve repair

Therapies such as direct tension-free microsurgical repair or transplantation of a nerve autograft,are nowadays used to treat traumatic peripheral nerve injuries（PNI）,focused on the enhancement of the intrinsic regenerative potential of injured axons.However,these therapies fail to recreate the suitable cellular and molecular microenvironment of peripheral nerve repair and in some cases,the functional recovery of nerve injuries is incomplete.Thus,new biomedical engineering strategies based on tissue engineering approaches through molecular intervention and scaffolding offer promising outcomes on the field.In this sense,evidence is accumulating in both,preclinical and clinical settings,indicating that platelet-rich plasma products,and fibrin scaffold obtained from this technology,hold an important therapeutic potential as a neuroprotective,neurogenic and neuroinflammatory therapeutic modulator system,as well as enhancing the sensory and motor functional nerve muscle unit recovery.

An inside-out vein graft filled with platelet-rich plasma for repair of a short sciatic nerve defect in rats

Platelet-rich plasma containing various growth factors can promote nerve regeneration. An inside-out vein graft can substitute nerve autograft to repair short nerve defects. It is hypothesized that an inside-out vein graft filled with platelet-rich plasma shows better effects in the repair of short sciatic nerve defects. In this study, an inside-out vein autograft filled with platelet-rich plasma was used to bridge a 10 mm-long sciatic nerve defect in rats. The sciatic nerve function of rats with an inside-out vein autograft filled with platelet-rich plasma was better improved than that of rats with a simple inside-out vein autograft. At 6 and 8 weeks, the sciatic nerve function of rats with an inside-out vein autograft filled with platelet-rich plasma was better than that of rats undergoing nerve autografting. Compared with the sciatic nerve repaired with a simple inside-out vein autograft, the number of myelinated axons was higher, axon diameter and myelin sheath were greater in the sciatic nerve repaired with an inside-out vein autograft filled with plateletrich plasma and they were similar to those in the sciatic nerve repaired with nerve autograft. These findings suggest that an inside-out vein graft filled with platelet-rich plasma can substitute nerve autograft to repair short sciatic nerve defects.

Platelet-rich plasma enhances adipose-derived stem cell-mediated angiogenesis in a mouse ischemic hindlimb model

AIM To evaluate the angiogenic effect of platelet-rich plasma(PRP)-preconditioned adipose-derived stem cells(ADSCs) both in vitro and in a mouse ischemic hindlimb model.METHODS ADSCs were divided based on culture medium: 2.5% PRP, 5% PRP, 7.5% PRP, and 10% PRP. Cell proliferation rate was analyzed using the MTS assay. The gene expression of CD31, vascular endothelial growth factor, hypoxia-inducible factors, and endothelial cell nitric oxide synthase was analyzed using reverse transcription polymerase chain reaction. Cell markers and structural changes were assessed through immunofluorescence staining and the tube formation assay. Subsequently, we studied the in vivo angiogenic capabilities of ADSCs by a mouse ischemic hindlimb model.RESULTS The proliferation rate of ADSCs was higher in the 2.5%, 5%, and 7.5% PRP groups. The expression of hypoxia-inducible factor, CD31, vascular endothelial growth factor, and endothelial cell nitric oxide synthase in the 5% and 7.5% PRP groups increased. The 5%, 7.5%, and 10% PRP groups showed higher abilities to promote both CD31 and vascular endothelial growth factor production and tubular structure formation in ADSCs. According to laser Doppler perfusion scan, the perfusion ratios of ischemic limb to normal limb were significantly higher in 5% PRP, 7.5% PRP, and human umbilical vein endothelial cells groups compared with the negative control and fetal bovine serum(FBS) groups(0.88 ± 0.08, 0.85 ± 0.07 and 0.81 ± 0.06 for 5%, 7.5% PRP and human umbilical vein endothelial cells compared with 0.42 ± 0.17 and 0.54 ± 0.14 for the negative control and FBS, P < 0.01).CONCLUSION PRP-preconditioned ADSCs presented endothelial cell characteristics in vitro and significantly improved neovascularization in ischemic hindlimbs. The optimal angiogenic effect occurred in 5% PRP-and 7.5% PRPpreconditioned ADSCs.

Content of blood cell components,inflammatory cytokines and growth factors in autologous platelet-rich plasma obtained by various methods

BACKGROUND The evaluation of the efficacy of platelet-rich plasma(PRP) in clinical practice yields conflicting results and raises numerous controversies. This may be due to different concentrations of biologically active components in PRP obtained with the use of different methods of gravity separation.AIM To compare the content, repeatability and correlations between biologically active components in PRP obtained with four different commercial systems.METHODS From a whole blood sample of each of 12 healthy male volunteers, 4 PRP samples were prepared using 4 different commercial kits [Arthrex Autologous Conditioned Plasma(ACP), Mini GPS Ⅲ, Xerthra, Dr. PRP] in accordance with the instructions provided by the manufacturers. A comparative analysis of blood cell components-13 selected inflammatory cytokines and 7 growth factors-in the obtained PRP samples was performed using the Kruskal-Wallis test by ranks. The repeatability of results in each method was evaluated by the estimation of the coefficient of variation. The Spearman correlation was used to estimate the relationship between blood cell content and cytokines.RESULTS Significantly higher concentrations of platelets(PLT), white blood cells(WBC) and red blood cells(RBC) were found in PRP obtained with the use of Mini GPS Ⅲ than in PRP obtained using other systems. Significant differences in the content of growth factors and cytokines in PRP were found. A positive correlation of the amount of PLT, RBC and WBC with the concentration of most of the growth factors was found but in only three inflammatory cytokines. The obtained correlations between blood cell components and cytokines differed between the systems in terms of statistical significance, which may be due to insufficient sample size. The repeatability of the obtained PLT concentration also varied between protocols with the lowest in Xerthra and the highest in Arthrex ACP.CONCLUSION Significant differences in the content of biologically active components and their repeatability were found in PRP obtained by various methods, providing new data for further research.