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In this study, the fused deposition modeling method was used to fabricate 3D-printed polycaprolactone (PCL). This study introduces a cost-effective post-fabrication treatment by using a Solubilized Amniotic Membrane (SAM) extracellular matrix (ECM) as a biological surface modifier. The employment of SAM provides an easy approach to overcoming the current challenges in the way of using fresh, cryopreserved, or dehydrated tissue. Four groups were included in this study, including neat PCL, oxygen plasma-treated PCL, SAM 0.001%w/v (SAM1), and SAM 0.005%w/v (SAM5). According to the SEM images, the diameter of each 3D-printed filament and filament distance were around 573 μm and 372 μm, respectively. The FTIR-ATR spectra confirmed the presence of amide groups in specimen, containing SAM. A higher weight loss rate was obtained for oxygen plasma-treated PCL and SAM-containing samples than neat PCL. The results of in vitro studies revealed that the optimized content of SAM (SAM 5) could promote the osteogenesis potency of Wharton-Jelly Mesenchymal Stem Cells (WJ-MSCs), cultured on the 3D-printed scaffolds in terms of alkaline phosphatase activity, calcium deposition and real-time PCR assessment of alkaline phosphatase, osteocalcin, and osteonectin. Also, in vivo, the collagen content in the control group and SAM 5 was 30.89 ± 1.73 and 44.24 ± 2.91, respectively. According to the Micro-CT assessment, the bone volume fraction was remarkably improved in the presence of SAM5 as it increased from 36.52 ± 1.56% in the control group to 42.66 ± 2.17% in SAM5. The results of the present study provide a promising surface modification approach by employing SAM for the future of bone tissue engineering scaffolds.

A major burden of the healthcare system resides in providing proper medical treatment for all types of chronic wounds, which are usually treated with dressings to induce a faster regeneration. Hence, to reduce healing time and improve the patient’s quality of life, it is extremely important to select the most appropriate constituent material for a specific wound dressing. A wide range of wound dressings exist but their mechanisms of action are poorly explored, especially concerning the immunomodulatory effects that occur from the interactions between immune cells and the biomaterial. Tissue-resident and monocyte-derived recruited macrophages are key regulators of wound repair. These phagocytic immune cells exert specific functions during the different stages of wound healing. The recognition of the substantial role of macrophages in the outcome of the wound healing process requires specific understanding of the immunomodulatory effects of commercially available or newly developed wound dressings. For a precise intervention, it is necessary to obtain more knowledge on macrophage polarization in different phases of wound healing in the presence of the dressings. The main purpose of this review is to collect clinical cases in which macrophage immunomodulation was taken into consideration as an indicator of the performances of novel or mainstream wound dressing materials, including those provided with antimicrobial properties.

IntroductionArthrofibrosis is a relatively frequent complication after total knee arthroplasty. Although stiffness after total hip arthroplasty (THA), because of formation of heterotopic ossification or other causes, is not uncommon, to the authors’ best knowledge, arthrofibrosis after THA has not been described. The aim of this study is to describe the arthrofibrosis of the hip after primary THA using an established clinical and histological classification of arthrofibrosis.Materials and methodsWe retrospectively examined all patients who were histologically confirmed to have arthrofibrosis after primary THA during revision surgery by examination of tissue samples in our clinic. Arthrofibrosis was diagnosed according to the histopathological SLIM-consensus classification, which defines seven different SLIM types of the periimplant synovial membrane. The SLIM type V determines the diagnosis of endoprosthesis-associated arthrofibrosis.ResultsThe study population consists of 66 patients who were revised due to arthrofibrosis after primary THA. All patients had a limitation in range of motion prior to revision with a mean flexion of 90° (range from 40 to 125), mean internal rotation of 10° (range from 0 to 40) and mean external rotation of 20° (range from 0 to 50). All patients had histological SLIM type V arthrofibrosis, corresponding to endoprosthesis-associated arthrofibrosis. Histological examination revealed that seven patients (10.6%) had particle-induced and 59 patients (89.4%) had non-particle-induced arthrofibrosis.ConclusionThis is the first description of endoprosthetic-associated arthrofibrosis after primary THA on the basis of a well-established histological classification. Our study results could enable new therapeutic and diagnostic opportunities in patients with such an arthrofibrosis. Surgeons should keep arthrofibrosis as a possible cause for stiffness and pain after primary THA in mind.Level of evidenceDiagnostic study, Level of Evidence IV.

IntroductionThe demand for total joint arthroplasty (TJA) is increasing worldwide with excellent long-term results. In general, TJA provides several benefits to the patients but also causes possible complications. The aim of our study was to describe trends in mortality after TJA in a high-volume arthroplasty center, and to examine the potential risk factors.MethodsFrom 1996 to 2018, a total of 103,560 patients (73,130 primary cases, 30,430 revision cases) underwent a TJA procedure in our institution. Anthropometric parameters, Charlson Comorbidity Index (CCI), pre- and postoperative hemoglobin (Hb), blood loss during surgery, postoperative complication (such as infection, deep vein thrombosis, pulmonary embolism, etc.) and cause of death from all patients who deceased during hospitalization were collected. The short-term mortality rate was analyzed between the primary and the revision groups.ResultsThe short-term mortality rate within our investigated groups was low with 0.041% in primary THA, 0.299% in revision THA, 0.045% in primary TKA, 0.205% in revision TKA, 0.214% in TSA/RSA, 0.15 % in primary TAA and 0% after TEA. Significant differences were found for preoperative Hb-values in patients undergoing septic revision (10.7 g/dl) compared to patients undergoing aseptic revision (12.8 g/dl) or primary arthroplasty (13.6 g/dl) (p < 0.001). Furthermore, we found significant differences regarding CCI between the groups. The comparison between causes of death (COD) showed a significantly higher number for pulmonary embolisms in the aseptic groups, while septic shock was the leading COD in the septic group and myocardial infarction as COD was found significantly more often after primary TJA.ConclusionThis is the largest single-center study presenting the short-term mortality rate following TJA. Consequently, TJA is a safe procedure with a low short-term mortality rate. However, depending on the type of surgery, certain risk factors cannot be eliminated. In order to further reduce the mortality, procedures as such should continue to be performed at specialized centers under standardized conditions.

Immune checkpoint inhibitors are used in the treatment of various cancers and have been extensively researched with regard to inflammatory and autoimmune diseases. However, this revolutionary therapeutic strategy often provokes critical auto-inflammatory adverse events, such as inflammatory reactions affecting the cardiovascular, gastrointestinal, nervous, and skeletal systems. Because the function of these immunomodulatory co-receptors is highly cell-type specific and the role of macrophages as osteoclast precursors is widely published, we aimed to analyze the effect of immune checkpoint inhibitors on these bone-resorbing cells. We established an model of osteoclastogenesis using human peripheral blood mononuclear cells, to which various immune checkpoints and corresponding antagonistic antibodies were administered. Formation of osteoclasts was quantified and cell morphology was analyzed immunofluorescence staining, cell size measurements, and calculation of cell numbers in a multitude of samples. These methodical approaches for osteoclast research achieved objective, comparable, and reproducible results despite the great heterogeneity in the form, size, and number of osteoclasts. In addition to the standardization of experimental analyses involving osteoclasts, our study has revealed the substantial effects of agonistic and antagonistic checkpoint modulation on osteoclastogenesis, confirming the importance of immune checkpoints in bone homeostasis. Our work will enable more robust and reproducible investigations into the use of immune checkpoint inhibitors in conditions with diminished bone density such as osteoporosis, aseptic loosening of endoprostheses, cancer, as well as the side effects of cancer therapy, and might even pave the way for novel individualized diagnostic and therapeutic strategies.

A correction to this paper has been published: https://doi.org/10.1007/s00402-021-03964-3

Wound infections constitute an increasing clinical problem worldwide. To reverse this trend, several wound dressings with antimicrobial properties have been developed. Considering the increasing presence of antibiotic-resistant microorganisms, product developers have been focusing their efforts in introducing antibiotic-free antibacterial wound dressings to the market, with silver being the most commonly incorporated antimicrobial agent. In this scenario, gaining information about the microbial and eukaryotic cells' response to these dressings is needed for a proper selection of antimicrobial dressings for the different cases of infected wounds. In particular, one insufficiently explored parameter is the effect of the dressings on the immunomodulation of macrophages, the main immune cell population participating in the repair process, because of their pivotal role in the transition of the inflammation to the proliferation phase of wound healing. In this work, three different clinically applied antimicrobial, silver impregnated wound dressings were selected: Atrauman Ag, Biatain Alginate Ag and PolyMem WIC Silver Non-adhesive. Antimicrobial susceptibility tests (disk diffusion and broth dilution), cell viability evaluation (CellTiter-Blue ) and experiments to determine macrophage polarization (e.g., flow cytometry, ELISA and glucose uptake) were performed after 24 h of incubation. Among all products tested, Biatain Alginate Ag induced the most evident bactericidal effect on Gram-positive and Gram-negative bacteria, followed by PolyMem WIC Silver Non-adhesive, but did not show good cytocompatibility . On the other hand, Atrauman Ag showed excellent cytocompatibility on L929 fibroblasts, HaCaT keratinocytes and THP-1 derived macrophages, but no significant antimicrobial activity was observed. Overall, it was confirmed that macrophages initiate, in fact, an alteration of their metabolism and phenotype in response to wound dressings of different composition in a short period of contact (24 h). M0 resting state macrophages common response to all silver-containing dressings used in this study was to increase the production of the anti-inflammatory cytokine TGF-β, which indicates an acquisition of M2-like macrophages characteristics.

The fouling resistance of zwitterionic coatings is conventionally explained by the strong hydrophilicity of such polymers. Here, the in vitro biocompatibility of a set of systematically varied amphiphilic, zwitterionic copolymers is investigated. Photocrosslinkable, amphiphilic copolymers containing hydrophilic sulfobetaine methacrylate (SPe) and butyl methacrylate (BMA) were systematically synthesized in different ratios (50:50, 70:30, and 90:10) with a fixed content of photo-crosslinker by free radical copolymerization. The copolymers were spin-coated onto substrates and subsequently photocured by UV irradiation. Pure pBMA and pSPe as well as the prepared amphiphilic copolymers showed BMA content-dependent wettability in the dry state, but overall hydrophilic properties a fortiori in aqueous conditions. All polysulfobetaine-containing copolymers showed high resistance against non-specific adsorption (NSA) of proteins, platelet adhesion, thrombocyte activation, and bacterial accumulation. In some cases, the amphiphilic coatings even outperformed the purely hydrophilic pSPe coatings.

Regenerative medicine has become an extremely valuable tool offering an alternative to conventional therapies for the repair and regeneration of tissues. The re-establishment of tissue and organ functions can be carried out by tissue engineering strategies or by using medical devices such as implants. However, with any material being implanted inside the human body, one of the conundrums that remains is the ease with which these materials can get contaminated by bacteria. Bacterial adhesion leads to the formation of mature, alive and complex three-dimensional biofilm structures, further infection of surrounding tissues and consequent development of complicated chronic infections. Hence, novel tissue engineering strategies delivering biofilm-targeted therapies, while at the same time allowing tissue formation are highly relevant. In this study our aim was to develop surface modified polyhydroxyalkanoate-based fiber meshes with enhanced bacterial anti-adhesive and juvenile biofilm disrupting properties for tissue regeneration purposes. Using reactive and amphiphilic star-shaped macromolecules as an additive to a polyhydroxyalkanoate spinning solution, a synthetic antimicrobial peptide, Amhelin, with strong bactericidal and anti-biofilm properties, and Dispersin B, an enzyme promoting the disruption of exopolysaccharides found in the biofilm matrix, were covalently conjugated to the fibers by addition to the solution before the spinning process. is one of the most problematic pathogens responsible for tissue-related infections. The initial antibacterial screening showed that Amhelin proved to be strongly bactericidal at 12 μg/ml and caused >50% reductions of biofilm formation at 6 μg/ml, while Dispersin B was found to disperse >70% of pre-formed biofilms at 3 μg/ml. Regarding the cytotoxicity of the agents toward L929 murine fibroblasts, a CC of 140 and 115 μg/ml was measured for Amhelin and Dispersin B, respectively. Optimization of the electrospinning process resulted in aligned fibers. Surface activated fibers with Amhelin and Dispersin B resulted in 83% reduction of adhered bacteria on the surface of the fibers. Additionally, the materials developed were found to be cytocompatible toward L929 murine fibroblasts. The strategy reported in this preliminary study suggests an alternative approach to prevent bacterial adhesion and, in turn biofilm formation, in materials used in regenerative medicine applications such as tissue engineering.

In the course of the further development of medicine with new therapeutic possibilities such as the steadily increasing implantation of foreign materials (such as catheters, stents, joint endoprosthesis and many more) as well as technical possibilities to perform increasingly complex operations (e.g., limb reconstructions, transplantations, etc.) or life-sustaining, intensive medical therapies on a daily basis, the use and consumption of antibiotics and antimycotics also increased (Charani et al., 2017). In connection with open bone fractures, penetrating contaminants and thus bacteria, surgeons are faced with the major problem of eliminating bacterial entry, preventing bacterial adhesion and thus biofilm formation on the implants and especially at the implant-bone interface, replacing lost bone substance and at the same time supporting fracture healing and bone regeneration, in addition to acute bone fracture treatment with temporary force-bearing implants (intramedullary nails, plate-screw systems, etc.). Due to their concentration-dependent toxicity to mammalian cells, nanoparticulate silver release systems in particular represent an interesting solution.Aabed and Mohammedshowed in their article that biogenic AgNPs capped and reduced by biomolecules such as carbohydrates and proteins result in safe, inexpensive and stable Ag+-releasing nanoparticles that could be useful in antimicrobial drug formulations. [...]it is not surprising that basic experimental research is viewed critically by the industry.