Aims. Trained immunity confers non-specific protection against various types of infectious diseases, including bone and joint infection. Platelets are active participants in the immune response to pathogens and foreign substances, but their role in trained immunity remains elusive. Methods. We first trained the innate immune system of C57BL/6 mice via intravenous injection of two toll-like receptor agonists (zymosan and lipopolysaccharide). Two, four, and eight weeks later, we isolated platelets from immunity-trained and control mice, and then assessed whether immunity training altered platelet releasate. To better understand the role of immunity-trained platelets in bone and joint infection development, we transfused platelets from immunity-trained mice into naïve mice, and then challenged the recipient mice with Staphylococcus aureus or Escherichia coli. Results. After immunity training, the levels of pro-inflammatory cytokines (tumour necrosis factor alpha (TNF-α), interleukin (IL)-17A) and chemokines (CCL5, CXCL4, CXCL5, CXCL7, CXCL12) increased significantly in platelet releasate, while the levels of anti-inflammatory cytokines (IL-4, IL-13) decreased. Other platelet-secreted factors (e.g. platelet-derived growth factor (PDGF)-AA, PDGF-AB, PDGF-BB, cathepsin D, serotonin, and histamine) were statistically indistinguishable between the two groups. Transfusion of platelets from trained mice into naïve mice reduced infection risk and bacterial burden after local or systemic challenge with either S. aureus or E. coli. Conclusion. Immunity training altered platelet releasate by increasing the levels of inflammatory cytokines/chemokines and decreasing the levels of anti-inflammatory cytokines. Transfusion of platelets from immunity-trained mice conferred protection against bone and joint infection, suggesting that alteration of platelet releasate might be an important mechanism underlying trained immunity and may have clinical implications. Cite this article: Bone Joint Res 2022;11(2):73–81

Objectives: Platelets are suggested to participate in the pathogenesis of rheumatoid arthritis. We showed for the first time in vivo an increase of platelet-endothelial cell interactions in mice with Antigen-induced-Arthritis (AiA). However, underlying mechanisms are not clear so far. Therefore, the aim of the present study was to investigate first the impact of P-selectin on AiA and second the influence of platelet P-Selectin on the endothelial damage and activation of leukocytes by means of intravital microscopy. Methods: In the first part C57/Bl6 and P-selectin deficient mice were disposed in four groups (n=7; control/AiA per strain). In the second part ex-vivo labelled platelets were transferred between different strains in AiA. The extent of AiA was assessed by knee joint swelling and by histological scoring. Platelet- and leukocyte-endothelium interactions were investigated. Results: In arthritic P-selectin deficient mice compared to arthritic C57/Bl6 mice, platelet interaction was significantly reduced and reached the level of both control groups without AiA. In addition interaction of leukocytes in P-selectin deficient arthritic animals was significantly decreased in comparison to arthritic C57/Bl6 animals. Swelling of the knee joint and histological score was reduced in arthritic P-selectin deficient mice compared to arthritic C57/Bl6 mice. In the second part a significant increase of leukocyte-endothelial cell interaction in P-selectin deficient arthritic recipients was shown if P-selectin sufficient platelets were donated. If P-selectin deficient platelets were donated, the number of adherent leukocytes was significantly reduced. Conclusion: We demonstrated for the first time in vivo a significant decrease of the interaction of platelets and leukocytes with the endothelium in P-selectin deficient mice with AiA and a reduction of clinical and histological symptoms of arthritis. Furthermore we showed that platelets provide storage of P-selectin for the recruitment of leukocytes in P-selectin deficient animals and therefore platelets seem to play a critical role in leukocyte-endothelial cell interaction. These findings suggest that P-Selectin is involved in the development and maintenance of arthritis and it could be at least partly responsible for the leukocyte tissue damage in AiA. Therefore, a reduced presence of P-selectin due to inhibition of platelets could be a new option for treatment of rheumatoid arthritis

Aims

Extracellular vesicles (EVs) are nanoparticles secreted by all cells, enriched in proteins, lipids, and nucleic acids related to cell-to-cell communication and vital components of cell-based therapies. Mesenchymal stromal cell (MSC)-derived EVs have been studied as an alternative for osteoarthritis (OA) treatment. However, their clinical translation is hindered by industrial and regulatory challenges. In contrast, platelet-derived EVs might reach clinics faster since platelet concentrates, such as platelet lysates (PL), are already used in therapeutics. Hence, we aimed to test the therapeutic potential of PL-derived extracellular vesicles (pEVs) as a new treatment for OA, which is a degenerative joint disease of articular cartilage and does not have any curative or regenerative treatment, by comparing its effects to those of human umbilical cord MSC-derived EVs (cEVs) on an ex vivo OA-induced model using human cartilage explants.

Aims

The diagnosis of periprosthetic joint infection (PJI) can be challenging as the symptoms are similar to other conditions, and the markers used for diagnosis have limited sensitivity and specificity. Recent research has suggested using blood cell ratios, such as platelet-to-volume ratio (PVR) and platelet-to-lymphocyte ratio (PLR), to improve diagnostic accuracy. The aim of the study was to further validate the effectiveness of PVR and PLR in diagnosing PJI.

Introduction

The ability of activated platelets to induce cellular proliferation is well recognised. In a previous diffusion model, platelets combined with Tri-calcium phosphate (TCP) led to an osteoprogenitor mitogenic response followed by cellular differentiation. This study was designed to look at osteoprogenitor responses when cultured directly onto TCP granules combined with activated platelets.

Purpose: Adding bone marrow cells to ceramic materials provides an osteoprogenic capacity favouring bony regrowth. Likewise, addition of platelets, which contain growth factors, might increase the rate of bone formation. The purpose of this work was to quantify in vitro the osteogenic potential obtained by adding platelet-rich plasma (PRP) to the bone marrow culture on ceramic materials.

Material and methods: PRP was obtained by centrifugation of blood and added to bone marrow cells harvested from the iliac crest and cultured on biphasic macroporous ceramic materials. Addition of PRP was repeated with platelet counts every two days. Differentiation of bone marrow cell into cells with osteogenic potential was evaluated by quantifying alkaline phosphatase activity after 15 days culture.

Results: Proliferation of mesenchymatous cells was clearly enhanced in cultures with PRP (+31%). Mean prevalence of phasphatase-alkaline-positive colonies was also improved after addition of PRP (+38%). Similarly, alkaline phosphatase activity was higher after addition of PRP (+31%).

Discussion: Adjunction of PRP to bone marrow cells cultured on ceramic materials stimulates proliferation of osteoblast-like cells. Increased cell proliferation and differentiation observed in vitro provides quantitative elements favouring the combination of platelets with bone grafts using bone substitutes.

Introduction and Aims: Reinfusion drains have been used to decrease the need for blood transfusion following total knee replacement. The aim of this study was to evaluate the degree of activation of platelets and leucocytes in both the blood that has been salvaged after total knee arthroplasty and the patients’ blood following reinfusion.

Method: A prospective series of 24 consecutive patients undergoing a primary total knee replacement in a case-control study were investigated. Post-operatively 12 patients received salvaged blood reinfusion and as a control, 12 patients underwent TKA with a standard drain. The reinfusion was initiated four hours after the operation. Blood samples were taken from all patients at three and five and a half to six hours post-operatively. A third sample was acquired in the treatment group from salvaged blood after reinfusion. Platelet, platelet-leucocyte and leucocyte activation markers were studied in both the drainage blood and the patients’ blood following reinfusion.

Results: Comparison between platelet, platelet-leucocyte and leucocyte activation markers in patients’ circulation prior to reinfusion compared to salvaged blood showed that almost all markers were significantly increased in salvaged blood. For example the platelet activation markers P-selectin (p< 0.01), Factor V (p< 0.01), CD40L (p< 0.01) and platelet derived microparticles (p< 0.01) were all significantly increased in the drainage blood. All studied platelet-leukocyte and leucocyte activation particles were also significantly increased. Following re-infusion of autologous salvaged blood there was no statistically measurable effect on activation markers of patients’ circulating platelets and leucocytes, but there was a slight drop in platelet count in the reinfused group compared to the control group. Levels of prothrombin fragment F 1+2 increased in the reinfused group compared to control indicating either activation of coagulation or simply the effect of addition of the high levels present in the salvage blood.

Conclusion: Blood from reinfusion drains showed a significant increase in activation of platelets and leukocytes indicating activation of coagulation. The reinfused blood did not lead to a difference in platelet and leukocyte activation but a decrease in platelets and an increase in fragment F1+2 suggests the possibility of activation of coagulation.

Aims

The primary aim was to assess the independent influence of coronavirus disease (COVID-19) on 30-day mortality for patients with a hip fracture. The secondary aims were to determine whether: 1) there were clinical predictors of COVID-19 status; and 2) whether social lockdown influenced the incidence and epidemiology of hip fractures.

Aims: to evaluate effects of trombocyte growth factors derived from platelets concentrate associate to intra-medullary nailing in stimulation of healing of diaphy-seal lower limbs pseudoarthroses.

Methods: 4 patients with atrophic tibial pseudoarthrosis and 2 patients with atrophic femoral pseudoartrhrosis were treated with high diameter reamed intramedullary nail. The site of pseudoarthrosis was stimulated using percutaneous injection of platelets concentrate under image intensifier control without opening. We evaluate healing of pseudoarthrosis with radiographic controls at 15 days, 1 month after surgery and after every month until consolidation. We gave partial weight bearing two days after surgery for 2 weeks and then total weight bearing.

Results: All patients with tibial fractures had radiological healing of pseudoarthrosis site within 3 months. All patient with femoral fracture healed in 4 months.

Conclusions: Although the number of treated patients is low and follow up is short, our results are remarkable either about consolidation or about early weight bearing.

There is good scientific rationale to support the use of growth factors to promote musculoskeletal tissue regeneration. However, the clinical effectiveness of platelet-rich plasma (PRP) and other blood-derived products has yet to be proven. Characterization and reporting of PRP preparation protocols utilized in clinical trials for the treatment of musculoskeletal disease is highly inconsistent, and the majority of studies do not provide sufficient information to allow the protocols to be reproduced. Furthermore, the reporting of blood-derived products in orthopaedics is limited by the multiple PRP classification systems available, which makes comparison of results between studies challenging. Several attempts have been made to characterize and classify PRP; however, no consensus has been reached, and there is lack of a comprehensive and validated classification. In this annotation, we outline existing systems used to classify preparations of PRP, highlighting their advantages and limitations. There remains a need for standardized universal nomenclature to describe biological therapies, as well as a comprehensive and reproducible classification system for autologous blood-derived products.

Cite this article: Bone Joint J 2019;101-B:891–896.

Rotator cuff tendon healing has proven to be a substantial clinical challenge. There is significant interest in finding biologic augmentation methods to improve this healing process. Two currently available products include platelet rich plasma/platelet rich fibrin matrix and several commercially available extra cellular matrix (ECM) patches. Platelet rich plasma is a sample of an autologous blood which has been centrifuged to a concentration of platelets three to four times that of normal. Platelets contain multiple growth factors, many of which have been shown to be involved in all phases in tendon healing. An alternative is platelet rich fibrin matrix. This forms a fibrin matrix with the platelets embedded within. Growth factors are subsequently released as the fibrin is reabsorbed. There are only a few studies which look at the effectiveness of platelet rich plasma and fibrin matrix. Overall, there is no strong evidence to support its routine use in the setting of rotator cuff repair. Extra cellular matrix patches are used to reinforce the strength of the repair and offload the tendon. They also provide the potential to form a scaffold for new growth and differentiation and may at some point be a delivery vehicle for cells and growth factors. There are currently two prospective randomised studies evaluating ECM patches – one showed that the patch studied was actually harmful to repair and the second suggested there was some benefit in larger tears. While there is not a lot of strong evidence to support routine use, further research and development is necessary to maximise this strategy

Aims

We aim to evaluate the usefulness of postoperative blood tests by investigating the incidence of abnormal results following total joint replacement (TJR), as well as identifying preoperative risk factors for abnormal blood test results postoperatively, especially pertaining to anaemia and acute kidney injury (AKI).

The identification of different substances able to promote a cellular response in terms of proliferation and differentiation the so-called “morphogenetic proteins”, has expanded research, aiming to identify the cellular elements that produce these proteins, in order to find a source for clinical application. Platelets have been identified as the main source of morphogenetic protein production: they can be separated in human blood samples and thus it is possible to create a concentration of these elements that, used both in bone as well as in soft tissues, promote a cellular response useful for tissue repair in terms of bone formation and soft tissue regeneration. Our experience takes into account different fields of application of this new technology: revision surgery, non-union treatment and repair of soft tissue in 18 patients. The same manufacturing process was utilized for all cases: ”Haemonetics” MCS”+ technology for apheresis, concentration of platelets and plasma/cryoprecipitate obtained, then mixed with autologous thrombin and calcium gluconate to obtain a gel. Usually, for bone surgery, platelet gel is mixed with an autologous iliac crest bone graft or, in some instances, with a homologous bone bank graft, usually morcelized chips. For soft tissue applications, after surgical débridement, the gel is directly applied over the site and covered by a soft bandage. No adverse effects have been observed: good results, in terms of bone healing and soft tissue repair, were obtained in all cases

Introduction. Platelets play a central role in haemostasis and wound healing. We have used autologous Platelet Rich Plasma (PRP) to stimulate healing in a variety of cases. We would like to present our early experience with this technique. Method. PRP is produced by centrifuging a sample of the patient’s blood. The volume of PRP produced is about 10% of the original volume. Thrombin, derived from the patient’s plasma, is mixed with the PRP to produce a platelet gel. This gel is semi-solid and makes the PRP more manageable intra-operatively. It can be used on its own, mixed with bone graft or de-mineralised bone matrix (DBM.). Results. We have used platelet gel in 14 cases for a variety of clinical conditions. 57% were males and the mean age was 44.1 (range: 7–77.) Cases included 3 elective joint fusions, 7 non unions, 2 case of chronic osteomyelitis, 1 acute fracture and 1 pathological fracture. The gel was mixed with autologous bone graft in 10 cases, DBM in 1 case and used on its own in 3 cases. The number of cases is too small to make any comment on the rate of bone union. Some practical issues have arisen during the use of platelet gel. Discussion. Is it better to give a large number of growth factors at slightly above background levels or a single growth factor millions of times above background level? This paper doesn’t answer that question but because wound and bone healing relies upon a cascade of growth factors, it is attractive to be able to provide many of these factors. Further studies are required to answer this fundamental question

Aims

While preoperative bloodwork is routinely ordered, its value in determining which patients are at risk of postoperative readmission following total knee arthroplasty (TKA) and total hip arthroplasty (THA) is unclear. The objective of this study was to determine which routinely ordered preoperative blood markers have the strongest association with acute hospital readmission for patients undergoing elective TKA and THA.

Introduction: Platelets play a central role in hemostasis and healing processes. Upon their activation, platelet alfa-granules release over 30 cytokines including platelet-derived growth factor (PDGF), transforming growth factor-alfa (TGF-alfa), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF), epidermal growth factor (EGF) and also active substances like serotonin, catecholamines, von Willebrand factor, proaccelerin, osteonectin and antimicrobial proteins. By concentrating platelets, platelet-rich plasma (PRP) with higher levels of growth factors might be reached, which could stimulate the healing processes. The activator for PRP is a mixture of thrombin and calcium chloride. After connecting these substances platelet-rich gel (PRG) is formed. Aims: In present study, we investigated in vitro antimicrobial activity of PRG after antibiotic administration. Material and Methods: 30 minutes after iv Amoxillin/ clavulanic acid administration 54 ml of whole blood was collected from each of 10 donors. PRPs were prepared with using GPS system from Biomet. In vitro laboratory susceptibility to PRG was determined by the Kirby-Bauer disc diffusion method on Mueller-Hinton agar (Becton Dickinson). Baseline antimicrobial activity was assessed by measuring the zones of inhibition. Agar plates were coated with one of the following strain: Staphylococcus aureus ATCC 43300 (MRSA), Staphylococcus aureus ATCC 25923 (MSSA), Klebsiella pneumoniae ATCC 700603 (ESBL), Escherichia coli ATCC 35218 (ESBL), Escherichia coli ATCC 25922, Enterococcus faecalis ATCC 29212 and Pseudomonas aeruginosa ATCC 27853. Results: We tested 10 samples of PRG. Zones of inhibition produced by PRG ranged between 6 – 23 mm in diameter. PRG inhibited the growth of Staphylococcus aureus. PG also was active against Escherichia coli, Enterococcus faecalis. No activity against Klebsiella pneumoniae and Pseudomonas aeruginosa was detected. Conclusions: Our previous study showed PRG no activity against Enterococcus faecalis without antibiotic administration. In this investigation we observed PRG strong activity against this bacteria after iv Amoxicillin-clavulanic acid administration. In infections during antibiotic treatment, PRG antimicrobial properties are enhanced by antibiotics that are concentrated in plasma

Purpose: The purpose of our study, is to determine the role of erythropoetin administration, as an alternative to homologous banked blood transfusions in total hip arthroplasty. Material and Methods: We have carried out a prospective randomized, controlled study on 60 patients having unilateral total hip replacement. In all the above patients, the same surgical team applied the same surgical technique (hybrid THA) and they followed the same rehabilitation program. We examined 2 groups of patients. In group A, all the patients received intraoperatively one unit of homologous blood transfusion (average 1 unit/patient), according to the volume of blood collected in the suction device and to the anaesthesiologist’s estimation. We also administered 40,000 units of erythropoetin subcutaneously one day before the operation followed by 40,000 units (sc) every 3 days in a total scheme of 4 doses. A control group of 30 patients (group B), in whom standard suction drains were used, received intraoperatively one or two units of homologous blood transfusion (average 1,7 units/patient), and also additional blood transfusions when required. The admission of banked blood transfusion was determined by the Haemoglobin value (< 9mg/dl) and/or clinical signs (blood pressure, pulse etc.). The values of Haemoglobin, Haematocrit and Platelets were recorded preoperatively and the 1st, 5th, and 15th day postoperatively. Results: 5 patients of group A required postoperatively 7 units of homologous blood (0,23 unit/patient) (total amount for group A 37 banked blood units 1,12 units/patient). 21 patients of group B required additional 28 banked blood units postoperatively (totally 79 banked blood units, or 2,63 units/patient). In the group A (study group), the total homologous blood requirements were reduced by 53%, the postoperative blood requirements were reduced by 75% and the number of patients that required additional blood transfusion was reduced by 67%. There was no significant difference noticed in the postoperative values of Haematocrit and Haemoglobin. Conclusions: The use of erythropoetin reduces effectively the postoperative demands of homologous banked blood transfusion in total hip arthroplasty

Autologous platelet rich plasma (PRP) has an established history of clinical use in dental and orthopaedic procedures. However, there is little scientific data demonstrating a mode of action and conflicting clinical data to support its use. The aim of this study was to determine the cellular and metabolic pathways by which PRP modulates the osteogenic response. PRP is a concentrate of platelets in a small volume of plasma derived from whole blood. Platelets contain pre-packaged growth factors in & #61537;-granules that are released during clotting at the trauma site and are an essential requirement for the hard (bone) and soft tissue healing process. S& N’s Caption ™ device, a standalone disposable device that prepares autologous PRP in 15minutes, was used to prepare human PRP. We determined a platelet concentration factor of 3.4& #61617;1.2 fold and significant increases in the concentration of platelet derived growth factor–AB (PDGF-AB), transforming growth factor-& #61538; (TGF-& #61538;) and vascular endothelial growth factor (VEGF). A 5.9 fold increase in VEGF, 4 fold increase in TGF-& #61538; and 1.5 fold increase in PDGF-AB indicate that PRP has the potential to enhance bone repair as each of these growth factors individually and synergistically affect multiple cell responses essential for tissue repair. An in vitro study was then undertaken to investigate the effect of human PRP compared to human serum on the proliferation and differentiation of human primary osteoblasts (hOBs) and human mesenchymal stem cells (hMSCs). A significant proliferative effect of PRP compared to serum was observed in both cell types. In hMSCs, PRP treatment significantly increased proliferation after 24 hours as determined by Pico green analysis. However, in osteoblasts a proliferative effect of PRP over and above that of serum was not observed until 72 hours. These data indicate that PRP may have specific differing stimulatory effects on each cell type. Quantitative RT-PCR analysis also determined that PRP significantly increased the expression of BMP 2 over and above that of serum in human osteoblasts at both 6 and 12 hour time points. Furthermore, in hMSCs, PRP increased both BMP-2 and alkaline phosphatase gene expression at early time points suggesting the commitment of these cells to the osteoblastic lineage. This hypothesis was consistent with alkaline phosphatase protein expression which was significantly increased at 72hrs in hMSCs and was further confirmed by increased alizarin red staining, indicative of calcium deposition, in long term cultures of hMCSs treated with PRP. In summary, these data demonstrate that PRP initiates proliferation in hMSCs and osteoblasts, enhances BMP-2 mRNA expression and induces osteoblast differentiation and maturation in human MSC cultures. Together these data demonstrate a positive effect of PRP on osteogenesis and highlight the potential for Caption™ derived PRP to enhance bone repair

In the last few years the study of the biology of fracture repair processes has isolated chemical mediators that induce and modulate bone repair. In orthopaedic surgery and traumatology, in cases of unsuccessful fracture setting, loss of bone and in the treatment of bone cavities it is advisable to associate a biological substitute in order to restore bone continuity and to maintain the mechanical properties of the skeletal segment. Platelets contain several growth factors (PDGF, TGFβ, EGF, IGF) capable of stimulating the proliferation of mesenchymal and mature cells such as fibroblasts and osteoblasts. The autologous platelet gel is obtained by separating and concentrating platelets from 450 ml of a patient’s blood. This procedure is simple, with a low risk of infections. It is free of immunogenic risk and it is comparatively cheap, considering the risk connected with a possible graft of homologous bone or with the use of allo- or xenograft. From 2003 we applied autologous platelet gel in eight patients: two cases of humerus pseudoarthrosis for exposed and plurifragmentary fractures, one with vascular and nerve injury; one forearm infected pseudoar-throsis with loss of bone and soft tissues caused by local drug injections; one infected ulnar pseudoarthrosis for high energy exposed proximal forearm and elbow fracture; one distal radius non-union after sub-amputation of distal forearm; one distal radius resection for TGC and implant of allograft epiphysis; one massive osteomyelitis of entire forearm after exposed distal radius fracture; and one humerus fracture in re-implanted arm with elbow arthrodesis. The patients were treated with surgical curettage of bone, iliac bone graft and autologous platelet gel; two received a vascularised fibular graft, all stabilised with internal fixation and six stabilised also with external fix-ation. They were immobilised for a mean of 3 months; then with a partial tutor they started physiotherapy. At the follow-up they were evaluated clinically and radiologically and with the DASH score. None of the patients had local or general post-operative complications; X-ray showed the restoration of regular skeletal filling. Only in one case was bone reabsorption seen in the distal humerus. All patients were satisfied and four of them returned to their pre-surgical occupation. The results of this application are difficult to standardise because of the complexity of each case. Imaging techniques are currently the only means to validate the remodelling process and to demonstrate its faster pace with platelet gel application. We are satisfied by the use of autologous platelet gel as a possible co-treatment in cases characterised by multiple surgical treatments with inactive pseudarthrosis and osteoepenia. The application is also simple, and the cost is relatively low with respect to the results obtained

Aims

The purpose of this study was to develop a personalized outcome prediction tool, to be used with knee arthroplasty patients, that predicts outcomes (lengths of stay (LOS), 90 day readmission, and one-year patient-reported outcome measures (PROMs) on an individual basis and allows for dynamic modifiable risk factors.