Explore the vast range of titles available.

Heterogeneous populations of human bone marrow-derived stromal cells (BMSC) are among the most frequently tested cellular therapeutics for treating degenerative and immune disorders, which occur predominantly in the aging population. Currently, it is unclear whether advanced donor age and commonly associated comorbidities affect the properties of -expanded BMSCs. Thus, we stratified cells from adult and elderly donors from our biobank ( = 10 and = 13, mean age 38 and 72 years, respectively) and compared their phenotypic and functional performance, using multiple assays typically employed as minimal criteria for defining multipotent mesenchymal stromal cells (MSCs). We found that BMSCs from both cohorts meet the standard criteria for MSC, exhibiting similar morphology, growth kinetics, gene expression profiles, and pro-angiogenic and immunosuppressive potential and the capacity to differentiate toward adipogenic, chondrogenic, and osteogenic lineages. We found no substantial differences between cells from the adult and elderly cohorts. As positive controls, we studied the impact of aging and inflammatory cytokine stimulation. Both conditions clearly affected the cellular properties, independent of donor age. We conclude that aging rather than donor aging influences BMSC characteristics.

There is increasing evidence that T lymphocytes play a key role in controlling endogenous regeneration. Regeneration appears to be impaired in case of local accumulation of CD8+ effector T cells (T ), impairing endogenous regeneration by increasing a primary \"useful\" inflammation toward a damaging level. Thus, rescuing regeneration by regulating the heightened pro-inflammatory reaction employing regulatory CD4+ T (T ) cells could represent an immunomodulatory option to enhance healing. Hypothesis was that CD4+ T might counteract undesired effects of CD8+ T . Using adoptive T transfer, bone healing was consistently improved in mice possessing an inexperienced immune system with low amounts of CD8+ T . In contrast, mice with an experienced immune system (high amounts of CD8+ T ) showed heterogeneous bone repair with regeneration being dependent upon the individual T /T ratio. Thus, the healing outcome can only be improved by an adoptive T therapy, if an unfavorable T /T ratio can be reshaped; if the individual CD8+ T percentage, which is dependent on the individual immune experience can be changed toward a favorable ratio by the T transfer. Remarkably, also in patients with impaired fracture healing the T /T ratio was higher compared to uneventful healers, validating our finding in the mouse osteotomy model. Our data demonstrate for the first time the key-role of a balanced T /T response following injury needed to reach successful regeneration using bone as a model system. Considering this strategy, novel opportunities for immunotherapy in patients, which are at risk for impaired healing by targeting T cells and supporting T cells to enhance healing are possible.

Objective Platelet-rich plasma (PRP) therapy is increasingly popular to treat musculoskeletal diseases, including tendinopathies and osteoarthritis (OA). To date, it remains unclear to which extent PRP compositions are determined by the immune cell and cytokine profile of individuals or by the preparation method. To investigate this, we compared leukocyte and cytokine distributions of different PRP products to donor blood samples and assessed the effect of pro-inflammatory cytokines on chondrocytes. Design For each of three PRP preparations (ACP®, Angel™, and nSTRIDE® APS), products were derived using whole blood samples from twelve healthy donors. The cellular composition of PRP products was analyzed by flow cytometry using DURAClone antibody panels (DURAClone IM Phenotyping Basic and DURAClone IM T Cell Subsets). The MESO QuickPlex SQ 120 system was used to assess cytokine profiles (V-PLEX Proinflammatory Panel 1 Human Kit, Meso Scale Discovery). Primary human chondrocyte 2D and 3D in vitro cultures were exposed to recombinant IFN-γ and TNF-α. Proliferation and chondrogenic differentiation were quantitatively assessed. Results All three PRP products showed elevated portions of leukocytes compared to baseline levels in donor blood. Furthermore, the pro-inflammatory cytokines IFN-γ and TNF-α were significantly increased in nSTRIDE® APS samples compared to donor blood and other PRP products. The characteristics of all other cytokines and immune cells from the donor blood, including pro-inflammatory T cell subsets, were maintained in all PRP products. Chondrocyte proliferation was impaired by IFN-γ and enhanced by TNF-α treatment. Differentiation and cartilage formation were compromised upon treatment with both cytokines, resulting in altered messenger ribonucleic acid (mRNA) expression of collagen type 1A1 ( COL1A1 ), COL2A1 , and aggrecan ( ACAN ) as well as reduced proteoglycan content. Conclusions Individuals with elevated levels of cells with pro-inflammatory properties maintain these in the final PRP products. The concentration of pro-inflammatory cytokines strongly varies between PRP products. These observations may help to unravel the previously described heterogeneous response to PRP in OA therapy, especially as IFN-γ and TNF-α impacted primary chondrocyte proliferation and their characteristic gene expression profile. Both the individual’s immune profile and the concentration method appear to impact the final PRP product. Trial registration This study was prospectively registered in the Deutsches Register Klinischer Studien (DRKS) on 4 November 2021 (registration number DRKS00026175).

Metallic implants are frequently used in medicine to support and replace degenerated tissues. Implant loosening due to particle exposure remains a major cause for revision arthroplasty. The exact role of metal debris in sterile peri‐implant inflammation is controversial, as it remains unclear whether and how metals chemically alter and potentially accumulate behind an insulating peri‐implant membrane, in the adjacent bone and bone marrow (BM). An intensively focused and bright synchrotron X‐ray beam allows for spatially resolving the multi‐elemental composition of peri‐implant tissues from patients undergoing revision surgery. In peri‐implant BM, particulate cobalt (Co) is exclusively co‐localized with chromium (Cr), non‐particulate Cr accumulates in the BM matrix. Particles consisting of Co and Cr contain less Co than bulk alloy, which indicates a pronounced dissolution capacity. Particulate titanium (Ti) is abundant in the BM and analyzed Ti nanoparticles predominantly consist of titanium dioxide in the anatase crystal phase. Co and Cr but not Ti integrate into peri‐implant bone trabeculae. The characteristic of Cr to accumulate in the intertrabecular matrix and trabecular bone is reproducible in a human 3D in vitro model. This study illustrates the importance of updating the view on long‐term consequences of biomaterial usage and reveals toxicokinetics within highly sensitive organs. Spatially micron‐ and nanoresolved synchrotron X‐ray fluorescence analyses of peri‐implant cancellous bone reveal specific distribution and accumulation patterns of metals released from alloys frequently used in knee and hip arthroplasty. These new insights of the local toxicokinetics of metallic debris prove that cobalt, chromium, and titanium exposure also occurs behind the insulating implant membrane, in the bone and bone marrow.

IntroductionOpen reduction and fixation are the standard of care for treating mandibular fractures and usually lead to successful healing. However, complications such as delayed healing, non-union, and infection can compromise patient outcomes and increase healthcare costs. The initial inflammatory response, particularly the response involving specific CD8+ T cell subpopulations, is thought to play a critical role in healing long bone fractures. In this study, we investigated the role of these immune cell profiles in patients with impaired healing of mandibular fractures.Materials and methodsIn this prospective study, we included patients with mandibular fractures surgically treated at Charité – Universitätsmedizin Berlin, Germany, between September 2020 and December 2022. We used follow-up imaging and clinical assessment to evaluate bone healing. In addition, we analyzed immune cell profiles using flow cytometry and quantified cytokine levels using electrochemiluminescence-based multiplex immunoassays in preoperative blood samples.ResultsOut of the 55 patients enrolled, 38 met the inclusion criteria (30 men and 8 women; mean age 32.18 years). Radiographic evaluation revealed 31 cases of normal healing and 7 cases of incomplete consolidation, including 1 case of non-union. Patients with impaired healing exhibited increased levels of terminally differentiated effector memory CD8+ T cells (TEMRA) and a higher TEMRA to regulatory T cell (Treg) ratio, compared with those with normal healing.ConclusionsOur analysis of mandibular fracture cases confirms our initial hypothesis derived from long bone fracture healing: monitoring the TEMRA to Treg ratio in preoperative blood can be an early indicator of patients at risk of impaired bone healing. Radiologic follow-up enabled us to detect healing complications that might not be detected by clinical assessment only. This study highlights the potential of individual immune profiles to predict successful healing and may form the basis for future strategies to manage healing complications.

Background Proximal humerus fractures (PHFs) are the third most common fractures in elderly patients. Over 70% of PHFs in patients aged over 60 are displaced fractures, often necessitating surgical treatment. However, osteosynthesis is associated with a high rate of complications, highlighting the urgent need for additional therapeutic approaches to enhance bone healing and prevent osteonecrosis. This study evaluates the safety, feasibility and potential efficacy of local prostacyclin (iloprost) to improve bone healing in patients with PHFs. Methods Thirty eligible patients will be randomized into one of three groups at a 1:1:1 ratio. All patients will receive angular stable locking plate fixation. Two treatment groups will receive an additional single dose of local iloprost through a 24-hour infusion postoperatively (group 1: low dose; group 2: high dose), while the control group will only receive the osteosynthesis. Patients will be monitored for 52 weeks. The primary endpoint is safety, with secondary endpoints including the preservation of the screw tip apex distance as an indicator of fracture healing, head shaft angle, necrosis rate, and patient-related outcome measures. Discussion The Ilobone study aims to provide data on the potential for biological augmentation of osteosynthesis procedures in PHFs, prone to healing challenges and complications. Trial registration The trial is registered with ClinicalTrial.gov (NCT04543682), registered 02 Sep. 2020, https://clinicaltrials.gov/show/NCT04543682 and the German Clinical Trials Registry (DRKS00027081), registered 10 Nov. 2021 https://drks.de/search/de/trial/DRKS00027081 .

Aims The BioBone consortium aims to validate circulating CD8 + TEMRA cells as a prognostic biomarker for predicting impaired fracture healing outcomes in a prospective, blinded, multicenter clinical study. The primary performance parameters are the pre-operative identification of at least 30% of patients who ultimately experience impaired healing at the first clinical endpoint, with a specificity greater than 90% to minimize the false-positive rate. Methods BioBone is a prospective, blinded, multicenter biomarker validation study designed to assess the prognostic value of circulating CD8 + TEMRA cells in fracture healing. A total of 640 patients aged 18 to 80 years with fractures of the humeral diaphysis, radial and/or ulnar diaphysis, femoral neck, trochanteric femur, femoral diaphysis, distal femur, proximal tibia, tibial diaphysis and distal tibia will be enrolled. The study is powered to validate the target assay performance and accounting for 6–7 potential confounders at an expected incidence of 10% impaired healing. Biomarker levels will be measured pre- and post-operatively using flow cytometry (FC) and patients will be monitored for one year. The primary endpoint is fracture healing status at 17–19 weeks (normal healing or delayed healing), while the secondary endpoint evaluates healing at nine months (delayed healing or pseudarthrosis). Fracture consolidation will be assessed through radiographs or computed tomography (CT) scans in conjunction with clinical assessments such as range of motion and weight-bearing capacity. Key outcome measures include radiographic analysis (RUST/RUSH scores), functional and patient-reported outcomes (e.g. weight bearing ability, range of motion, and the SF-36 questionnaire), as well as socioeconomic parameters (e.g. work capacity, rehabilitation needs, mobility). The predictive performance (sensitivity, specificity, NPV, PPV) of the biomarker will be determined in a prospective, double-blinded analysis, where CD8 + TEMRA blood levels are measured prior to surgical treatment and healing status at clinical endpoints is assessed by independent observers. Additional immunological examination and in vitro analysis of blood and fracture hematoma samples will further investigate the mechanism of action of CD8 + TEMRA cells in impaired human bone regeneration. Conclusion The BioBone study will validate the suitability of CD8 + TEMRA cells as a prognostic marker for impaired fracture healing and their integration into routine clinical practice. The results could have a global impact by incorporating immune-based prognostic tools into clinical workflows, paving the way for precision medicine approaches in trauma care. The BioBone study is funded by the German Federal Ministry of Education and Research (BMBF).

Introduction: Mechanical loading is known to determine the course of bone fracture healing. We hypothesise that lower limb long bone loading differs with knee flexion angle during walking and frontal knee alignment, which affects fracture healing success. Materials and methods: Using our musculoskeletal in silico modelling constrained against in vivo data from patients with instrumented knee implants allowed us to assess internal loads in femur and tibia. These internal forces were associated with the clinical outcome of fracture healing in a relevant cohort of 178 extra-articular femur and tibia fractures in patients using a retrospective approach. Results: Mean peak forces differed with femoral compression (1,330–1,936 N at mid-shaft) amounting to about half of tibial compression (2,299–5,224 N). Mean peak bending moments in the frontal plane were greater in the femur (71–130 Nm) than in the tibia (from 26 to 43 Nm), each increasing proximally. Bending in the sagittal plane showed smaller mean peak bending moments in the femur (−38 to 43 Nm) reaching substantially higher values in the tibia (−63 to −175 Nm) with a peak proximally. Peak torsional moments had opposite directions for the femur (−13 to −40 Nm) versus tibia (15–48 Nm) with an increase towards the proximal end in both. Femoral fractures showed significantly lower scores in the modified Radiological Union Scale for Tibia (mRUST) at last follow-up ( p < 0.001) compared to tibial fractures. Specifically, compression ( r = 0.304), sagittal bending ( r = 0.259), and frontal bending ( r = −0.318) showed strong associations ( p < 0.001) to mRUST at last follow-up. This was not the case for age, body weight, or localisation alone. Discussion: This study showed that moments in femur and tibia tend to decrease towards their distal ends. Tibial load components were influenced by knee flexion angle, especially at push-off, while static frontal alignment played a smaller role. Our results indicate that femur and tibia are loaded differently and thus require adapted fracture fixation considering load components rather than just overall load level.

Circulating, blood-borne SARS-CoV-2-reactive memory T cells in persons so far unexposed to SARS-CoV-2 or the vaccines have been described in 20-100% of the adult population. They are credited with determining the efficacy of the immune response in COVID-19. Here, we demonstrate the presence of preexisting memory CD4 + T cells reacting to peptides of the spike, membrane, or nucleocapsid proteins of SARS-CoV-2 in the bone marrow of all 17 persons investigated that had previously not been exposed to SARS-CoV-2 or one of the vaccines targeting it, with only 15 of these persons also having such cells detectable circulating in the blood. The preexisting SARS-CoV-2-reactive memory CD4 + T cells of the bone marrow are abundant and polyfunctional, with the phenotype of central memory T cells. They are tissue-resident, at least in those persons who do not have such cells in the blood, and about 30% of them express CD69. Bone marrow resident SARS-CoV-2-reactive memory CD4 + memory T cells are also abundant in vaccinated persons analyzed 10-168 days after 1°-4° vaccination. Apart from securing the bone marrow, preexisting cross-reactive memory CD4 + T cells may play an important role in shaping the systemic immune response to SARS-CoV-2 and the vaccines, and contribute essentially to the rapid establishment of long-lasting immunity provided by memory plasma cells, already upon primary infection.

Professional soccer players have a lengthy playing season, throughout which high levels of physical stress are maintained. The following recuperation period, before starting the next pre-season training phase, is generally considered short but sufficient to allow a decrease in these stress levels and therefore a reduction in the propensity for injury or musculoskeletal tissue damage. We hypothesised that these physical extremes influence the body composition, blood flow, and endothelial/immune function, but that the recuperation may be insufficient to allow a reduction of tissue stress damage. Ten professional football players were examined at the end of the playing season, at the end of the season intermission, and after the next pre-season endurance training. Peripheral blood flow and body composition were assessed using venous occlusion plethysmography and DEXA scanning respectively. In addition, selected inflammatory and immune parameters were analysed from blood samples. Following the recuperation period a significant decrease of lean body mass from 74.4+/-4.2 kg to 72.2+/-3.9 kg was observed, but an increase of fat mass from 10.3+/-5.6 kg to 11.1+/-5.4 kg, almost completely reversed the changes seen in the pre-season training phase. Remarkably, both resting and post-ischemic blood flow (7.3+/-3.4 and 26.0+/-6.3 ml/100 ml/min) respectively, were strongly reduced during the playing and training stress phases, but both parameters increased to normal levels (9.0+/-2.7 and 33.9+/-7.6 ml/100 ml/min) during the season intermission. Recovery was also characterized by rising levels of serum creatinine, granulocytes count, total IL-8, serum nitrate, ferritin, and bilirubin. These data suggest a compensated hypo-perfusion of muscle during the playing season, followed by an intramuscular ischemia/reperfusion syndrome during the recovery phase that is associated with muscle protein turnover and inflammatory endothelial reaction, as demonstrated by iNOS and HO-1 activation, as well as IL-8 release. The data provided from this study suggest that the immune system is not able to function fully during periods of high physical stress. The implications of this study are that recuperation should be carefully monitored in athletes who undergo intensive training over extended periods, but that these parameters may also prove useful for determining an individual's risk of tissue stress and possibly their susceptibility to progressive tissue damage or injury.