Introduction. Platelet Rich Plasma (PRP) is widely used in clinical praxis. Especially the effects in musculoskeletal repair studies are diverse and an augmentation of healing processes stays questionable. However, diverse cell culture studies reported promising results, which seem not be transferable into the clinical situation. We therefore performed a cell culture study which better reflects the clinical situation: the autologous stimulation of human tendon cells with PRP. Materials and Methods. Human tenocyte-like cells (hTLCs) from 24 donors (12 male/female) with supraspinatus tendon tears were isolated and characterized. The donors were grouped into 4 groups according to their age (</> 65 years) and sex. During follow up, approximately 2.5 years after initial surgery, the patients donated blood for PRP preparation (Ethic vote and written informed consent). Growth factors and platelets were quantified and the effect of autologous stimulation of the hTLCs was measured by analysis of cell proliferation, Collagen I synthesis and expression of Collagen I, III and Osteocalcin. Results. The platelet concentration for the 4 groups was between 3.6–4.5 × 10. 5. platelets/µl (reference level: 1.5–3×10. 5. platelets/µl blood). PRP contained high amounts of IGF-1, lower amounts of TGF-β1 and PDGF-AB. PDGF-AB concentration significantly correlated with platelet concentration and the TGF-β1 concentration. The amounts of BMP-7 and −12 were underneath the detection limits of the assays. Cell proliferation was positively affected by PRP exposure when compared to controls (2% FCS and 10% FCS) (p<0.05). However, the expression and synthesis of Collagen I was significantly reduced compared to controls. Collagen III expression was partly increased, while Osteocalcin expression was not affected. Discussion. PRP is a source of growth factors such as IGF-1, TGF-β and PDGF-AB. It has a high potential to stimulate cell proliferation, which might have a positive effect in clinical applications. However, the decreased expression and synthesis of Collagen I, the most important Collagen in the tendon, might explain the, to date, less satisfactory clinical results. PRPs might have their potential in chronic situation with pain reducing function rather than in acute healing situations. Further studies are necessary to better understand these mechanisms

Introduction and Objective. Platelet-Rich-plasma (PRP) has been used in combination with stem cells, from different sources, with encouraging results both in vitro and in vivo in osteochondral defects management. Adipose-derived Stem Cells (ADSCs) represents an ideal resource for their ease of isolation, abundance, proliferation and differentiation properties into different cell lineages. Furthermore, Stem Cells in the adipose tissue are more numerous than from other sources. Aim of this study was to evaluate the potential of ADSCs in enhancing the effect of arthroscopic mesenchymal stimulation combined with infiltration of PRP. Materials and Methods. The study includes 82 patients. 41 patients were treated with knee arthroscopy, Steadman microfractures technique and intraoperative PRP infiltration, Group A. In the Group B, 41 patients were treated knee arthroscopy, Steadman microfractures and intraoperative infiltration of PRP and ADSCs (Group B). Group A was used as a control group. Inclusion criteria were: Age between 40 and 65 years, Outerbridge grade III-IV chondral lesions, Kellegren-Lawrence Grade I-II. Patient-reported outcome measures (PROMs) evaluated with KOOS, IKDC, VAS, SF-12 were assessed pre-operatively and at 3 weeks, 6 months, 1-year post-operative. 2 patients of Group A and 3 patients of Group B, with indication of Puddu plate removal after high tibial osteotomy (HTO), underwent an arthroscopic second look, after specific informed consent obtained. On this occasion, a bioptic sample was taken from the repair tissue of the chondral lesion previously treated with Steadman microfractures. Results. PROMs showed statistically significant improvement (p <0.05) with comparable results in both groups. The histological examination of the bioptic samples in Group B showed a repair tissue similar to hyaline cartilage, according to the International Cartilage Repair Society (ICRS) Visual Histological Assessment Scale. In Group A, the repair tissue was fibrocartilaginous. Conclusions. According to the PROMs and the histological results, showing repair tissue after Steadman microfractures qualitatively similar to hyaline cartilage, the combination of ADSCs and PRP could represent an excellent support to the arthroscopic treatment of focal chondral lesions and mild to moderate osteoarthritis

We investigated the effect of Platelet Rich Plasma (PRP) in tendon healing. The aim was to assess the effect of an application of PRP on angiogenesis and immunohistochemical expression of TGF-b1 and IGF-I during tendon healing. We used a patellar tendon defect model after resecting its central portion. 48 skeletally mature New Zealand White rabbits were divided into the respective group and each group they were randomised into controls and PRP treated cases. The rabbits were sacrificed at weekly intevals and histological and immunohistological assessments were performed. The results showed a faster healing rate, increased vascularity, and higher expression of the growth factors in the PRP group. We conclude that the mixture of growth factors present in PRP gel improved the rate and quality of tendon healing

Introduction. Whilst most cases of plantar fasciitis can be resolved with existing conservative established treatment options, a few intractable cases can be difficult to resolve. New biologic treatments have been proposed for a variety of soft tissue tendon problems. We evaluated the results of PRP in the treatment of recalcitrant chronic cases of plantar fasciitis. Methods. Patients with plantar fasciitis that had not responded to a minimum of 8 months standard conservative management (eccentric stretching, physiotherapy, cortisone injection, night splints) were offered PRP therapy. The injection into the tender spot at the proximal plantar fascial insertion was performed in theatre as a day case. Roles Maudsley (RM) scores, Visual analogue scores (VAS) for pain, AOFAS scores and ‘would have injection again’ were collated pre-operatively, at three and six months. Results. Prospective data was collected on 39 patients (44 heels – 15 males, 24 females; mean age 51 years, range 25–79 years). No complications were noted. At six months review RM score improved from 3.8 to 2.5 (p<0.001), VAS improved from 7.7 to 4.2 (p<0.001) and AOFAS improved from 61 to 82 (p<0.001). 21 patients had complete relief of symptoms on 3 months review. 25 patients were very satisfied with the clinical improvement and would have the injection again. Whilst there was a slight improvement in scores from 3 to 6 months, this was not significant. 3 patients with bilateral injections on the same sitting did not improve, though 2 patients with bilateral injections on separate sittings did improve. Conclusion. In this series of chronic intractable cases, PRP injection produced a 64% satisfaction rate from patients. The procedure was safe with no reported complications. The authors feel PRP for plantar fasciitis may have some role in treatment and merits further study with a prospective randomised trial

Aims. The present study investigates the effectiveness of platelet-rich plasma (PRP) gel without adjunct to induce cartilage regeneration in large osteochondral defects in a rabbit model. Methods. A bilateral osteochondral defect was created in the femoral trochlear groove of 14 New Zealand white rabbits. The right knees were filled with PRP gel and the contralateral knees remained untreated and served as control sides. Some animals were killed at week 3 and others at week 12 postoperatively. The joints were harvested and assessed by Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) MRI scoring system, and examined using the International Cartilage Repair Society (ICRS) macroscopic and ICRS histological scoring systems. Additionally, the collagen type II content was evaluated by the immunohistochemical staining. Results. After 12 weeks post-surgery, the defects of the PRP group were repaired by hyaline cartilage-like tissue. However, incomplete cartilage regeneration was observed in the PRP group for three weeks. The control groups showed fibrocartilaginous or fibrous tissue, respectively, at each timepoint. Conclusion. Our study proved that the use of PRP gel without any adjuncts could successfully produce a good healing response and resurface the osteochondral defect with a better quality of cartilage in a rabbit model. Cite this article: Bone Joint Res 2021;10(3):192–202

Platelet Rich Plasma (PRP) has shown to be a general stimulation for repair and 1 year results showed promising success percentages. To determine the effectiveness of PRP compared with corticosteroid injections in patients with chronic lateral epicondylitis with a two-year follow-up. A double-blind randomized controlled trial was conducted between May 2006 and January 2008. The trial was conducted in two Dutch teaching hospitals. 100 patients with chronic lateral epicondylitis were randomly assigned to a leucocyte-enriched PRP group (n=51) or in the corticosteroid group (n=49). Randomization and allocation to the trial group were carried out by a central computer system. Patients received either a corticosteroid injection or an autologous platelet concentrate injection through a peppering needling technique. The primary analysis included Visual Analogue Scale (VAS) pain scores and Disabilities of the Arm, Shoulder, and Hand Outcome (DASH) scores. The PRP group was more often successfully treated than the corticosteroid group (p<.0001). Success was defined as a reduction of 25% on VAS or DASH scores without a re-intervention after 2 years. When baseline VAS and DASH scores were compared with the scores at 2 years follow-up, both groups significantly improved across time (intention-to-treat principle). However, the DASH scores of the corticosteroid group returned back to baseline levels, while the PRP significantly improved (as-treated principle). There were no complications related to the use of PRP. Treatment of patients with chronic lateral epicondylitis with PRP reduces pain and increases function significantly, exceeding the effect of corticosteroid injection even after a follow-up of two years. Future decisions for application of PRP for lateral epicondylitis should be confirmed by further follow-up from this trial and should take into account possible costs and harms as well as benefits

Following the recognition of platelet rich plasma (PRP) as an interventional procedure by NICE, patients who had failed standard conservative treatment for chronic elbow tendinitis and referred for surgery were recruited prospectively into a PRP injection study. 52 patients at Torbay Hospital, Devon, UK received PRP injections in 18 months and 37 had a minimum of 6 months follow up. The outcomes in these patients are summarised. There were 16 males and 21 females. 30 had tennis elbow and 7 had golfers elbow. All patients had their symptoms for a minimum of 6 months and had failed to improve with standard conservative treatment. 2 had a failed outcome from previous tennis elbow release surgery. The PRP injections were carried out under ultrasound guidance after correlating the tender spot with neovascularisation on flow Doppler. 31 patients had a single injection; the other 21 patients had 2 injections. Quick DASH score and patients own self-satisfaction was used to measure outcome. 18 patients (48%) were discharged by 6 months. DASH score worsened in 7 patients (19%) and 2 of these patients opted to have surgery, which had no benefit either. No complications were observed with the use of PRP. Overall, by using PRP injections, surgery was avoided in 35 patients (95%) at 18 months and nearly half of the patients were discharged from follow up by 6 months

Introduction. Ostochondral lesion of the knee is a common cause of chronic knee pain. Arthroscopic treatment with subcondral microfracture is a widespread technique leading to noticeable improvement of knee function and pain. To improve the effectiveness of this treatment options, we thought to add intra (PRF) or post-operative (PRP) growth factors. Platelet rich plasma (PRP) is obtained by centrifugation of the blood to produce a plasma with high concentration of platelets and growth factors. This latter represents a promising method to manage degenerative cartilage lesion and can be used postoperatively to improve clinical results of patients treated arthroscopically. Platelet Rich Fibrin (PRF) has been presented as a second-generation platelet concentrate, and it is used intraoperatively to cover the microfracuteres’ holes. No literature was found about using of PRF intraoperative in association with arthroscopic microfracture technique. The aim of this study is to compare clinical outcomes of the treatment of knee osteochondral lesion using arthroscopic microfracture technique alone or in association with PRF Intraoperative application using “Vivostat” system or with PRP “ReGen Lab” postoperative injection. Patients & Methods. 90 patients with clinical and radiographic evidence of osteochondral lesion of the medial or lateral compartment of the knee were enrolled. All patients received arthroscopic debridement and Microfractures and were randomised into 3 groups: 30 patients received microfractures and intraoperative PRF “Vivostat” injection(Group A), 30 patients received microfracture and 3 intra-articular injections of 5.5 mL PRP “Regen”(Group B), 30 patients received microfracture only. IKDC, KOOS and VAS score were administered to all patients before starting the treatment, at 1, 6 and 12 months from the end of the management. Results. Patients who received microfracture and PRF intraoperative application provided the best outcomes, showing a significant higher clinical scores (P<0.001) compared to the other two groups. Patients underwent PRP postoperative administration reported significant higher score than those undergoing arthroscopic microfracture alone (P<0.005), but lesser than Intraoperative PRF group at 6 months and 1 year follow up. Discussion/Conclusion. Treatment of osteochondral lesions of the knee using microfracture technique significantly improved functional and pain scores from the pre- to postoperatively time in the overall cohort. Intraoperative application of PRF shows significantly better outcome than postoperative PRP injections. However, additional treatment with intra-articular PRP injection as an adjunct to microfracture technique may offer better clinical outcomes over microfracture technique alone

Aims

The use of biologics in the treatment of musculoskeletal injuries in Olympic and professional athletes appears to be increasing. There are no studies which currently map the extent, range, and nature of existing literature concerning the use and efficacy of such therapies in this arena. The objective of this scoping review is to map the available evidence regarding the use of biologics in the treatment of musculoskeletal injuries in Olympic and professional sport.

Aims. To determine whether platelet-rich plasma (PRP) injection improves outcomes two years after acute Achilles tendon rupture. Methods. A randomized multicentre two-arm parallel-group, participant- and assessor-blinded superiority trial was undertaken. Recruitment commenced on 28 July 2015 and two-year follow-up was completed in 21 October 2019. Participants were 230 adults aged 18 years and over, with acute Achilles tendon rupture managed with non-surgical treatment from 19 UK hospitals. Exclusions were insertion or musculotendinous junction injuries, major leg injury or deformity, diabetes, platelet or haematological disorder, medication with systemic corticosteroids, anticoagulation therapy treatment, and other contraindicating conditions. Participants were randomized via a central online system 1:1 to PRP or placebo injection. The main outcome measure was Achilles Tendon Rupture Score (ATRS) at two years via postal questionnaire. Other outcomes were pain, recovery goal attainment, and quality of life. Analysis was by intention-to-treat. Results. A total of 230 participants were randomized, 114 to PRP and 116 to placebo. Two-year questionnaires were sent to 216 participants who completed a six-month questionnaire. Overall, 182/216 participants (84%) completed the two-year questionnaire. Participants were aged a mean of 46 years (SD 13.0) and 25% were female (57/230). The majority of participants received the allocated intervention (219/229, 96%). Mean ATRS scores at two years were 82.2 (SD 18.3) in the PRP group (n = 85) and 83.8 (SD 16.0) in the placebo group (n = 92). There was no evidence of a difference in the ATRS at two years (adjusted mean difference -0.752, 95% confidence interval -5.523 to 4.020; p = 0.757) or in other secondary outcomes, and there were no re-ruptures between 24 weeks and two years. Conclusion. PRP injection did not improve patient-reported function or quality of life two years after acute Achilles tendon rupture compared with placebo. The evidence from this study indicates that PRP offers no patient benefit in the longer term for patients with acute Achilles tendon rupture. Cite this article: Bone Joint J 2022;104-B(11):1256–1265

There are a number of patients in whom hip preservation surgery is not indicated as they have developed signs of early osteoarthritis, and nor can they have a hip replacement as they are too early in the disease process. The use of PRP in OA of the hip has not been studied systematically and this study concisely collates all the available data in the use of PRP in Hip OA. This systematic review and meta-analysis aimed to assess intra-articular platelet-rich plasma as a therapeutic intervention for hip osteoarthritis, including the duration of efficacy, influence of dose and composition of PRP, and the incidence of adverse effects. We performed literature searches on the MEDLINE, EMBASE, CINHAL, WEB OF SCIENCE, COCHRANE and SCOPUS databases, and PRSIMA guidelines were followed. Data was pooled using random effects meta-analysis. We assessed quality of the included studies using the Methodological Index for Non-Randomised Studies (MINORS) instrument, with an additional assessment for Randomised Controlled Trials with the Revised Cochrane risk-of-bias tool for randomized trials (RoB 2). Eight studies were included in the analysis, with data from a total of 331 patients. PRP significantly reduced pain compared to baseline at multiple timepoints, with the greatest effect at 1–2mo follow-up. PRP only significantly improved function at the 1–2mo follow-up. A significantly larger reduction in pain was achieved with a single injection or PRP compared to multiple injections, a total injected dose of PRP <15mL compared to ≥15mL or using a leukocyte-poor PRP preparation compared to leukocyte-rich PRP. There were no lasting adverse effects. Low and moderate quality evidence suggests that PRP reduces pain and improves function at endpoint compared to baseline. Moderate quality evidence suggests a larger reduction in pain is achieved with a single injection of PRP compared to multiple injections, and low quality evidence attributes a larger reduction of pain with a total injected dose of PRP <15mL compared to ≥15mL or using leukocyte-poor PRP compared to leukocyte-rich PRP

Background. Disability and slow return to sport and work after tendon rupture are major challenges. Platelet Rich Plasma (PRP) is an autologous supraphysiological concentration of platelets from whole blood that has demonstrated positive cellular and physiological effects on healing in laboratory conditions but evidence from adequately powered robust clinical trials is lacking. We aimed to determine the clinical efficacy of PRP for treatment of acute Achilles tendon rupture. Methods. In a placebo-controlled, participant- and assessor-blinded, trial at 19 NHS hospitals we randomly assigned 230 adults starting acute Achilles rupture non-surgical management to PRP injection or dry-needle insertion (placebo) to the rupture gap under local anaesthetic. Patients with confounding or contraindicated concurrent medical conditions were excluded. The primary outcome was muscle-tendon function, assessed by the limb symmetry index (LSI, uninjured limb/injured limb × 100, higher scores better) of the work (Joules) performed during the heel-rise endurance test at 24 weeks. Secondary outcomes were: Achilles Tendon Rupture Score (ATRS, 0–100, higher scores better), quality of life (SF-12), pain, and goal attainment. Trial registration: ISRCTN54992179. Results. Participants were aged mean 46 years and 57 (25%) were female. 103/114 (90%) of the PRP group and all (n=116) in the placebo group received allocated treatment. At 24 weeks, mean LSI was 34.4 for the PRP group and 38.8 for placebo (adjusted mean difference −4.4 95% CI −11.2 to 2.5, n=201) and ATRS was mean 65.2 PRP vs 65.8 (adjusted mean difference −0.6, 95% CI −4.9 to 3.7, n=224). There were no differences between groups in the other secondary outcomes. Conclusion. We found no evidence of PRP efficacy for improving muscle-tendon function or patient-reported recovery after acute Achilles tendon rupture. Our findings challenge the increasing global use of PRP for acute tendon injury and indicate that robust evaluations are required in other applications

Background. The PATH-2 trial found no evidence of a benefit of Platelet Rich Plasma (PRP) injection versus a placebo after Achilles tendon rupture (ATR) at six-months. ATR often leave longer-term functional deficiencies beyond six-months. This study aim is to determine if PRP affect tendon functional outcomes at two-years after rupture. Study design. Randomised multi-centre two-arm parallel-group, participant- and assessor-blinded, superiority trial. Methods. Adults with acute ATR managed non-surgically were recruited in 19 UK hospitals from 2015 to 2019. Exclusions were insertion or musculotendinous injuries, leg injury or deformity, diabetes, haematological disorder, corticosteroids and anticoagulation therapy. Participants were randomised via an online system 1:1 to PRP or placebo. Primary outcome was Achilles Tendon Rupture Score (ATRS) at two-years. Secondary outcomes were pain, Patient-Specific Functional Scale (PSFS), SF-12 and re-rupture. Assessors were blinded. Intention-to-treat and Compliance Average Causal effects (CACE) analyses were carried out. Consistency of effects across subgroups age, BMI, smoking and gender were assessed using Forest plots. Pearson's correlation was used to explore ATRS correlation with blood and growth factors. Results. 216/230 (94%) participants completed the 6-months follow-up were contacted. 182/216 (84%) completed the two-year follow-up. Participants were aged mean 46 (SD 13.0), 57 female/159 male. 96% received the allocated intervention. Two-years ATRS scores were 82.2 (SD 18.3) in the PRP group (n=85) and 83.8 (SD 16.0) in the placebo group (n=92). There was no evidence of a difference in the two-years ATRS (adjusted-mean difference −0.752 95%CI −5.523 to 4.020, p=0.757), or in any secondary outcome, and no re-rupture between at two-years. Neither PRP cellular or growth factors correlated with the two-year ATRS. Conclusion. PRP did not improve patient-reported function or quality of life two-years after acute Achilles tendon rupture, compared with placebo, indicating that PRP offers no patient benefit in the longer term

Abstract. Introduction. This study aimed to assess the effect of PRP on knee articular cartilage content (thickness and/or volume) and establish if there is a correlation between changes in cartilage and clinical outcomes in patients with knee osteoarthritis. Methodology. A systematic review was performed following the Cochrane methodology. Studies were included if they reported on cartilage content with MRI or Ultrasound before and after the injection. A random-effects model meta-analysis was performed. Results. 11 studies (n=786) from 1,453 records met the inclusion criteria, with five (n=444) being RCTs. The PRP treatment protocol varied widely. Follow-up ranged from 6–12 months. Eight studies reported increase in cartilage content in the PRP group as compared to control (four showing significant difference). In meta-analysis: PRP treatment was not associated with a significant increase in cartilage thickness in medial and lateral femoral condyle, or in the overall cartilage content (4 studies, n=187, Hedges’ g: 0.079; 95%CI: 0.358-0.516; p=0.723). Meta-analysis of 3 RCTs (n=112) showed no significant difference in increasing cartilage content overall with PRP injections compared with no PRP (Hedges’ g: 0.217; 95%CI: -0.177 – 0.611; P=0.281). There was no correlation between changes in cartilage and clinical outcomes following PRP treatment. Conclusion. Treatment of knee osteoarthritis with PRP is not associated with a significant increase in articular cartilage content and any effect on cartilage is not associated with better clinical outcomes. A multi-centre, adequately powered RCT, with a standardized preparation / administration protocol assessing long-term effect of PRP in knee osteoarthritis is needed to guide clinical care

Platelet-rich plasma (PRP) has been demonstrated to benefit a variety of disciplines. But there exists heterogeneity in results obtained due to lack of standardization of the preparation protocols employed in them. We aim to identify and standardize a preparation protocol for PRP with maximum recovery of platelets to obtain reproducible results across studies. Blood samples were collected from 20 healthy volunteers. The double spin protocol of PRP preparation was analyzed for variables such as centrifugal acceleration, time, and volume of blood processed and final product utilized. The final PRP prepared was investigated for platelet recovery, concentration, integrity, and viability. We noted maximum platelet recovery (86-99%) with a mean concentration factor of 6-times baseline, with double centrifugation protocol at 100xg and 1600xg for 20 minutes each. We also noted that 10 ml of blood in a 15 ml tube was the ideal volume of blood to be processed to maximize platelet recovery. We demonstrated that the lower 1/3rd is the ideal volume to be utilized for clinical application. We did not note a loss of integrity or viability of the platelets in the final product from the above-said protocol. Preparation of PRP by the double spin protocol of 10 ml of blood at 100xg and 1600xg for 20 minutes each in a 15ml tube and using the lower 1/3rd of the final product demonstrated consistent high platelet recovery (86-99%) and concentration (6x) without disturbing the platelet integrity or viability

Degenerative disc disease, associated to low back pain, afflicts more than 50% of humans, and represents a major healthcare problem, especially for the pathology initiation. Current treatments range from conservative strategies to more invasive surgical techniques, such as disc removal and vertebral fusion. In the Intervertebral Disease (IVD) the nucleus pulposus (NP) degeneration is a key factor for the pathology initiation. Several tissue engineering approaches aiming to restore the appropriate NP cell (NPCs) and matrix content, were attempted by using adult stromal cells either from bone marrow or adipose tissue, chondrocytes, notochordal cells and more recently also pluripotent stem cells. However, none was fully satisfactory since the NP acid and a-vascularized environment appeared averse to the implanted heterologous cells. Several studies demonstrated the efficacy of platelet derivatives such as platelet rich plasma (PRP) in promoting the regeneration of connective tissues. We investigated the efficacy of PRP on NPCs proliferation and differentiation with the goal to propose the direct stimulation of resident cells (stimulation of endogenous cells – less invasive surgical procedure) or the implantation of NPCs expanded in vitro in the presence of PRP as therapeutic agents in IVD degeneration. NPCs were isolated from small fragments of NP explants, cultivated in medium supplemented with PRP or FCS (standard condition control) and characterized by FACS analysis for the expression of the typical mesenchymal stem cells markers CD34, CD44, CD45, CD73, CD90 and CD105. NPCs cultured in PL showed a phenotypic profile like the cells cultured in FCS. However, compared to NPCs expanded in the presence of FCS, NPCs expanded in PRP showed a much better proliferation and differentiation capacity. NPCs differentiation was evaluated by the cell ability to produce an organized metachromatic cartilaginous matrix, confirmed by the positive immunohistochemical staining for chondrogenic markers

Platelet Rich Plasma (PRP), either rich (L-PRP) or poor (P-PRP) of leukocytes, is frequently used as an anti-inflammatory and regenerative tool in osteoarthritis (OA). PRP contains proteins but not genes as it is derived from megakaryocytes. Proteomics but not metabolomics of PRP was recently studied. Metabolomics is a field of ‘omics’ research involved in comprehensive portrayal of the small molecules, metabolites, in the metabolome. These small molecules can be endogenous metabolites or exogenous compounds found in an organism (1). Our aim was to determine the difference between L-PRP and P-PRP. A cross-sectional clinical study was designed in six recreational male athletes between the ages of 18 and 35 years. 3 mL P-PRP and 3 mL -LPRP was prepared from 60 mL of venous blood after treating with 9 mL of sodium citrate and centrifugation at 2.700 rpm for 10 min. Half of the prepared PRP's were frozen at −20°C for a week. Fresh and frozen samples were analyzed at the Q-TOF LC/MS device after thawing to room temperature. Untargeted metabolomic results revealed that the metabolomic profile of the L-PRP and P-PRP were significantly different from each other. A total of 33.438 peaks were found. Statistically significant (p<0.05) peaks were uploaded to the MetaboAnalyst 5.0 platform. Exogenous out of 2.308 metabolites were eliminated and metabolites found significant for our study were subjected to pathway analysis. Steroid biosynthesis, sphingolipid metabolism and metabolism of lipid pathways were affected. In the L-PRP samples, Nicotinamide riboside (FC: 2.2), MHPG (FC: 3.0), estrone sulfate (FC: 7.5), thiamine diphosphate (FC: 2.0), leukotriene E4 (FC: 7.5), PC(18:1 (9Z)e/2:0) (FC: 9.8) and Ap4A (FC: 2.1) were higher compared to P-PRP. C24 sulfatide (FC: −11.8), 3-hexaprenyl-4,5-dihydroxybenzoic acid (FC: −2.8) metabolites were furthermore lower in P-PRP. Clinical outcomes of PRP application should consider these metabolic pathways in future studies (2)

Aims. For cementless implants, stability is initially attained by an interference fit into the bone and osteo-integration may be encouraged by coating the implant with bioactive substances. Blood based autologous glue provides an easy, cost-effective way of obtaining high concentrations of growth factors for tissue healing and regeneration with the intention of spraying it onto the implant surface during surgery. The aim of this study was to incorporate nucleated cells from autologous bone marrow (BM) aspirate into gels made from the patient’s own blood, and to investigate the effects of incorporating three different concentrations of platelet rich plasma (PRP) on the proliferation and viability of the cells in the gel. Methods. The autologous blood glue (ABG) that constituted 1.25, 2.5, and 5 times concentration PRP were made with and without equal volumes of BM nucleated cells. Proliferation, morphology, and viability of the cells in the glue was measured at days 7 and 14 and compared to cells seeded in fibrin glue. Results. Overall, 2.5 times concentration of PRP in ABG was capable of supporting the maximum growth of cells isolated from the BM aspirate and maintain their characteristics. Irrespective of PRP concentration, cells in ABG had statistically significantly higher viability compared to cells in fibrin glue. Conclusion. In vitro this novel autologous gel is more capable of supporting the growth of cells in its structure for up to 14 days, compared to commercially available fibrin-based sealants, and this difference was statistically significant. Cite this article: Bone Joint Res 2020;9(7):402–411

Objectives. Platelet-rich plasma (PRP) is being used increasingly often in the clinical setting to treat tendon-related pathologies. Yet the optimal PRP preparations to promote tendon healing in different patient populations are poorly defined. Here, we sought to determine whether increasing the concentration of platelet-derived proteins within a derivative of PRP, platelet lysate (PL), enhances tenocyte proliferation and migration in vitro, and whether the mitogenic properties of PL change with donor age. Methods. Concentrated PLs from both young (< 50 years) and aged (> 50 years) donors were prepared by exposing pooled PRP to a series of freeze-thaw cycles followed by dilution in plasma, and the levels of several platelet-derived proteins were measured using multiplex immunoassay technology. Human tenocytes were cultured with PLs to simulate a clinically relevant PRP treatment range, and cell growth and migration were assessed using DNA quantitation and gap closure assays, respectively. Results. Platelet-derived protein levels increased alongside higher PL concentrations, and PLs from both age groups improved tenocyte proliferation relative to control conditions. However, PLs from aged donors yielded a dose-response relationship in tenocyte behaviour, with higher PL concentrations resulting in increased tenocyte proliferation and migration. Conversely, no significant differences in tenocyte behaviour were detected when increasing the concentration of PLs from younger donors. Conclusion. Higher PL concentrations, when prepared from the PRP of aged but not young donors, were more effective than lower PL concentrations at promoting tenocyte proliferation and migration in vitro. Cite this article: D. R. Berger, C. J. Centeno, N. J. Steinmetz. Platelet lysates from aged donors promote human tenocyte proliferation and migration in a concentration-dependent manner. Bone Joint Res 2019;8:32–40. DOI: 10.1302/2046-3758.81.BJR-2018-0164.R1

Aims. This study investigates the effects of intra-articular injection of adipose-derived mesenchymal stem cells (AdMSCs) and platelet-rich plasma (PRP) on lameness, pain, and quality of life in osteoarthritic canine patients. Methods. With informed owner consent, adipose tissue collected from adult dogs diagnosed with degenerative joint disease was enzymatically digested and cultured to passage 1. A small portion of cells (n = 4) surplus to clinical need were characterized using flow cytometry and tri-lineage differentiation. The impact and degree of osteoarthritis (OA) was assessed using the Liverpool Osteoarthritis in Dogs (LOAD) score, Modified Canine Osteoarthritis Staging Tool (mCOAST), kinetic gait analysis, and diagnostic imaging. Overall, 28 joints (25 dogs) were injected with autologous AdMSCs and PRP. The patients were followed up at two, four, eight, 12, and 24 weeks. Data were analyzed using two related-samples Wilcoxon signed-rank or Mann-Whitney U tests with statistical significance set at p < 0.05. Results. AdMSCs demonstrated stem cell-like characteristics. LOAD scores were significantly lower at week 4 compared with preinjection (p = 0.021). The mCOAST improved significantly after three months (p = 0.001) and six months (p = 0.001). Asymmmetry indices decreased from four weeks post-injection and remained significantly lower at six months (p = 0.025). Conclusion. These improvements in quality of life, reduction in pain on examination, and improved symmetry in dogs injected with AdMSCs and PRP support the effectiveness of this combined treatment for symptom modification in canine OA for six months. Cite this article: Bone Joint Res 2021;10(10):650–658