European cells & materials最新文献

Impaired bone-fracture healing is associated with long-term musculoskeletal disability, pain and psychological distress. Low-intensity pulsed ultrasound (LIPUS) is a non-invasive and side-effect-free treatment option for fresh, delayed- and non-union bone fractures, which has been used in patients since the early 1990s. Several clinical studies, however, have questioned the usefulness of the LIPUS treatment for the regeneration of long bones, including those with a compromised healing. This systematic review addresses the hurdles that the clinical application of LIPUS encounters. Low patient compliance might disguise the effects of the LIPUS therapy, as observed in several studies. Furthermore, large discrepancies in results, showing profound LIPUS effects in regeneration of small-animal bones in comparison to the clinical studies, could be caused by the suboptimal parameters of the clinical set-up. This raises the question of whether the so-called "acoustic dose" requires a thorough characterisation to reveal the mechanisms of the therapy. The adequate definition of the acoustic dose is especially important in the elderly population and patients with underlying medical conditions, where distinct biological signatures lead to a delayed regeneration. Non-industry-funded, randomised, double-blind, placebo-controlled clinical trials of the LIPUS application alone and as an adjuvant treatment for bones with complicated healing, where consistent control of patient compliance is ensured, are required.

Space missions provide the opportunity to investigate the influence of gravity on the dynamic remodelling processes in bone. Mice were examined following space flight and subsequent recovery to determine the effects on bone compartment-specific microstructure and composition. The resulting bone loss following microgravity recovered only in trabecular bone, while in cortical bone the tissue mineral density was restored after only one week on Earth. Detection of TRAP-positive bone surface cells in the trabecular compartment indicated increased resorption following space flight. In cortical bone, a persistent reduced viability of osteocytes suggested an impaired sensitivity to mechanical stresses. A compartment-dependent structural recovery from microgravity-induced bone loss was shown, with a direct osteocytic contribution to persistent low bone volume in the cortical region even after a recovery period. Trabecular recovery was not accompanied by changes in osteocyte characteristics. These post-space-flight findings will contribute to the understanding of compositional changes that compromise bone quality caused by unloading, immobilisation, or disuse.

Due to the complexity of the structure of the tooth periodontium, regeneration of the full tooth attachment is not a trivial task. There is also a gap in models that can represent human tooth attachment in vitro and in vivo. The aim of this study was to develop a bilayered in vitro construct that simulated the tooth periodontal ligament and attached alveolar bone, for the purpose of tissue regeneration and investigation of physiological and orthodontic loading. Two types of materials were used to develop this construct: sol-gel 60S10Mg derived scaffold, representing the hard tissue component of the periodontium, and commercially available Geistlich Bio-Gide® collagen membrane, representing the soft tissue component of the tooth attachment. Each scaffold was dynamically seeded with human periodontal ligament cells (HPDLCs). Scaffolds were either cultured separately, or combined in a bilayered construct, for 2 weeks. Characterisation of the individual scaffolds and the bilayered constructs included biological characterisation (cell viability, scanning electron microscopy to confirm cell attachment, gene expression of periodontium regeneration markers), and mechanical characterisation of scaffolds and constructs. HPDLCs enjoyed a biocompatible 3-dimensional environment within the bilayered construct components. There was no drop in cellular gene expression in the bilayered construct, compared to the separate scaffolds.

Osteomyelitis associated with periprosthetic joint infection (PJI) signals a chronic infection and the need for revision surgery. An osteomyelitic bone exhibits distinct morphological features, including evidence for osteolysis and an accelerated bone remodelling into poorly organised, poor-quality bone. In addition to immune cells, various bone cell-types have been implicated in the pathology. The present study sought to determine the types of bone-cell activities in human PJI bones. Acetabular biopsies from peri-implant bone from patients undergoing revision total hip replacement (THR) for chronic PJI (with several identified pathogens) as well as control bone from the same patients and from patients undergoing primary THR were analysed. Histological analysis confirmed that PJI bone presented increased osteoclastic activity compared to control bone. Analysis of osteocyte parameters showed no differences in osteocyte lacunar area between the acetabular bone taken from PJI patients or primary THR controls. Analysis of bone matrix composition using Masson's trichrome staining and second-harmonic generation microscopy revealed widespread lack of mature collagen, commonly surrounding osteocytes, in PJI bone. Increased expression of known collagenases, such as matrix metallopeptidase (MMP) 13, MMP1 and cathepsin K (CTSK), was measured in infected bone compared to non-infected bone. Human bone and cultured osteocyte-like cells experimentally exposed to Staphylococcus aureus exhibited strongly upregulated expression of MMP1, MMP3 and MMP13 compared to non-exposed controls. In conclusion, the study identified previously unrecognised bone-matrix changes in PJI caused by multiple organisms deriving from osteocytes. Histological examination of bone collagen composition may provide a useful adjunct diagnostic measure of PJI.

Treatment strategies for progressive intervertebral-disc degeneration often alleviate pain and other symptoms. With the goal of developing strategies to promote the regeneration of the nucleus pulposus (NP), the present study tried to identify the biological effects of hydrostatic (HP) and osmotic pressures on NP cells. The study hypothesis was that a repetitive regimen of cyclic HP followed by constant HP in high-osmolality medium would increase anabolic molecules in NP cells. Bovine NP cells/clusters were enclosed within semi-permeable membrane pouches and incubated under a regimen of cyclic HP for 2 d followed by constant HP for 1 d, repeated 6 times over 18 d. NP cells showed a significantly increased expression of anabolic genes over time: aggrecan, chondroitin sulfate N-acetylgalactosaminyltransferase 1, hyaluronan synthase 2, collagen type 2 (p < 0.05). In addition, the expression of catabolic or degenerative genes (matrix metalloproteinase 13, collagen type 1) and cellular characteristic genes (proliferating cell nucleic antigen, E-cadherin) was suppressed. The amount of sulfated glycosaminoglycan increased significantly at day 18 compared to day 3 (p < 0.01). Immunostaining revealed deposition of extracellular-matrix molecules and localization of other specific molecules corresponding to their genetic expression. An improved understanding of how cells respond to physicochemical stresses will help to better treat the degenerating disc using either cell- or gene-based therapies as well as other potential matrix-enhancing therapies. Efforts to apply these tissue-engineering and regenerative-medicine strategies will need to consider these important physicochemical stresses that may have a major impact on the survivability of such treatments.

Intervertebral disc (IVD) degeneration and the consequent low-back pain (LBP) affect over 80 % of people in western societies, constituting a tremendous socio-economic burden worldwide and largely impairing patients' life quality. Extracellular matrix (ECM)-based scaffolds, derived from decellularised tissues, are being increasingly explored in regenerative medicine for tissue repair. Decellularisation plays an essential role for host cells and antigen removal, while maintaining native microenvironmental signals, including ECM structure, composition and mechanical properties, which are essential for driving tissue regeneration. With the lack of clinical solutions for IVD repair/regeneration, implantation of decellularised IVD tissues has been explored to halt and/or revert the degenerative cascade and the associated LBP symptoms. Over the last few years, several researchers have focused on the optimisation of IVD decellularisation methods, combining physical, chemical and enzymatic treatments, in order to successfully develop a cell-free matrix. Recellularisation of IVD-based scaffolds with different cell types has been attempted and numerous methods have been explored to address proper IVD regeneration. Herein, the advances in IVD decellularisation methods, sterilisation procedures, repopulation and biocompatibility tests are reviewed. Additionally, the importance of the donor profile for therapeutic success is also addressed. Finally, the perspectives and major hurdles for clinical use of the decellularised ECM-based biomaterials for IVD are discussed. The studies reviewed support the notion that tissue-engineering-based strategies resorting to decellularised IVD may represent a major advancement in the treatment of disc degeneration and consequent LBP.

No optimal therapy exists to stop or cure chondral degeneration in osteoarthritis (OA). While the pathogenesis is unclear, there is consensus on the etiological involvement of both articular cartilage and subchondral bone. Compared to original bone, the substance of sclerotic bone is mechanically less solid. The osteoproliferative effect of Mg has been shown repeatedly during development of Mg-based osteosynthesis implants. The aim of the present study was to examine the influence of implanted high-purity Mg cylinders on subchondral bone quality in a rabbit OA model. 10 New Zealand White rabbits received into the knee either 20 empty drill holes or 20 drill holes, which were additionally filled with one Mg cylinder each. Follow-up was at 8 weeks. Micro-computed tomography (µCT) was performed. After euthanasia, cartilage condition was determined, bone samples were collected and processed for histological evaluation and elemental imaging by micro-X-ray fluorescence spectrometry (µXRF). Articular cartilage collected post-mortem showed different stages of lesions, from mild alterations up to exposed subchondral bone, which tended to be slightly lower in animals with implanted Mg cylinders. µCT showed significantly increased bone volume in the Mg group. Also, histological evaluation revealed distinct differences. While right, operated limbs did not show any significant difference, left, non-operated controls showed significantly less changes in articular cartilage in the Mg group. A distinct influence of implanted cylinders of pure Mg on subchondral bone of osteoarthritic rabbits was shown. Subsequent evaluations, including other time points and alternative alloys, will show if this could alter OA progression.

Sheep are one of the many animal models used to investigate the pathophysiology of disc degeneration and the regenerative strategies for intervertebral disc (IVD) disease. To date, few studies have thoroughly explored ageing of ovine lumbar IVDs. Hence, the objective of the present study was to concomitantly assess the development of spontaneous age-related lumbar IVD degeneration in sheep using X-ray, magnetic resonance imaging (MRI) as well as histological analyses. 8 young ewes (< 48 months old) and 4 skeletally mature ewes (> 48 months old) were included. Disc height, Pfirrmann and modified Pfirrmann grades as well as T2-wsi and T2 times were assessed by X-ray and MRI. The modified Boos score was also determined using histology sections. Pfirrmann (2 to 3) and modified Pfirrmann (2 to 4) grades as well as Boos scores (7 to 13) gradually increased with ageing, while T2-weighted signal intensity (1.18 to 0.75), T2 relaxation time (114.36 to 70.65 ms) and disc height (4.1 to 3.2 mm) decreased significantly. All the imaging modalities strongly correlated with the histology (p < 0.0001). The present study described the suitability of sheep as a model of age-related IVD degeneration by correlation of histological tissue alterations with the changes observed using X-ray and MRI. Given the structural similarities with humans, the study demonstrated that sheep warrant being considered as a pertinent animal model to investigate IVD regenerative strategies without induction of degeneration.

The most prevalent pathogen in bone infections is Staphylococcus aureus; its incidence and severity are partially determined by host factors. Prior studies showed that anti-glucosaminidase (Gmd) antibodies are protective in animals, and 93.3 % of patients with culture-confirmed S. aureus osteomyelitis do not have anti-Gmd levels > 10 ng/mL in serum. Infection in patients with high anti-Gmd remains unexplained. Are anti-Gmd antibodies in osteomyelitis patients of the non-opsonising, non-complement-fixing IgG4 isotype? The relative amounts of IgG4 and total IgG against Gmd and 7 other S. aureus antigens: iron-surface determinants (Isd) IsdA, IsdB, and IsdH, amidase (Amd), α-haemolysin (Hla), chemotaxis inhibitory protein from S. aureus (CHIPS), and staphylococcal-complement inhibitor (SCIN) were determined in sera from healthy controls (Ctrl, n = 92), osteomyelitis patients whose surgical treatment resulted in infection control (IC, n = 95) or an adverse outcome (AD, n = 40), and post-mortem (PM, n = 7) blood samples from S. aureus septic-death patients. Anti-Gmd IgG4 levels were generally lower in infected patients compared to controls; however, levels among the infected were higher in AD than IC patients. Anti-IsdA, IsdB and IsdH IgG4 levels were increased in infected patients versus controls, and Jonckheere-Terpstra tests of levels revealed an increasing order of infection (Ctrl < IC < AD < PM) for anti-Isd IgG4 antibodies and a decreasing order of infection (Ctrl > IC > AD > PM) for anti-autolysin (Atl) IgG4 antibodies. Collectively, this does not support an immunosuppressive role of IgG4 in S. aureus osteomyelitis but is consistent with a paradigm of high anti-Isd and low anti-Atl responses in these patients.

The orthopaedic and trauma community have faced the threat of infection since the introduction of operative fracture fixation many decades ago. The parallel emergence and spread of antimicrobial resistance in clinically relevant pathogens has the potential to significantly complicate patient care. This editorial serves to provide a global context to the issue of antimicrobial resistance and how infectious disease research in general plays a crucial role both on a global scale as evidenced by the current pandemic, but also on a more personal scale for the daily management of orthopaedic trauma patients. The special issue on Orthopaedic Infection in the eCM journal provides a snapshot of the clinically relevant basic research that is being performed in this field.