An in vitro evaluation of inflammation response of titanium functionalized with heparin/fibronectin complex

Advances in osteoimmunomodulation of biomaterials after intrabone implantation: focus on surface hydrophilicity

Biomaterials intended for intrabone implantation are extensively utilized in orthopedic and dental applications. Their surface properties, particularly hydrophilicity, significantly influence the biological interactions surrounding the implant, ultimately determining the implant's in vivo fate. Recently, the role of osteoimmunomodulation in these implantable biomaterials has been recognized for its importance in regulating biomaterial-mediated osteogenesis. Consequently, it is imperative to elucidate the correlation between hydrophilicity and the immune response for the development of osteoimmunomodulatory implants. Herein, this review highlights recent advances in osteoimmunomodulation of biomaterials after intrabone implantation from a novel perspective-surface hydrophilicity, and summarizes the series of immune reactions and subsequent bone remodeling that occur in response to hydrophilic implants, focusing on protein adsorption, the behaviors of major immune cells, and osteoimmunomodulation-enhanced angiogenesis and osteogenesis. Hydrophilic biomaterials have the capacity to alter the surrounding immune microenvironment and accelerate the process of material-tissue bonding, thereby facilitating the successful integration of biomaterials with tissue. Collectively, the authors hope that this article provides strategies for modulating hydrophilicity to achieve osteoimmunomodulatory performance and further promotes the development of novel implantable biomaterials for orthopedic and dental applications.

Brain delivery of fibronectin through bioactive phosphorous dendrimers for Parkinson's disease treatment via cooperative modulation of microglia

Effective treatment of Parkinson's disease (PD), a prevalent central neurodegenerative disorder particularly affecting the elderly population, still remains a huge challenge. We present here a novel nanomedicine formulation based on bioactive hydroxyl-terminated phosphorous dendrimers (termed as AK123) complexed with fibronectin (FN) with anti-inflammatory and antioxidative activities. The created optimized AK123/FN nanocomplexes (NCs) with a size of 223 nm display good colloidal stability in aqueous solution and can be specifically taken up by microglia through FN-mediated targeting. We show that the AK123/FN NCs are able to consume excessive reactive oxygen species, promote microglia M2 polarization and inhibit the nuclear factor-kappa B signaling pathway to downregulate inflammatory factors. With the abundant dendrimer surface hydroxyl terminal groups, the developed NCs are able to cross blood-brain barrier (BBB) to exert targeted therapy of a PD mouse model through the AK123-mediated anti-inflammation for M2 polarization of microglia and FN-mediated antioxidant and anti-inflammatory effects, thus reducing the aggregation of α-synuclein and restoring the contents of dopamine and tyrosine hydroxylase to normal levels in vivo. The developed dendrimer/FN NCs combine the advantages of BBB-crossing hydroxyl-terminated bioactive per se phosphorus dendrimers and FN, which is expected to be extended for the treatment of different neurodegenerative diseases.

Decoding the "Fingerprint" of Implant Materials: Insights into the Foreign Body Reaction

Foreign body reaction (FBR) is a prevalent yet often overlooked pathological phenomenon, particularly within the field of biomedical implantation. The presence of FBR poses a heavy burden on both the medical and socioeconomic systems. This review seeks to elucidate the protein "fingerprint" of implant materials, which is generated by the physiochemical properties of the implant materials themselves. In this review, the activity of macrophages, the formation of foreign body giant cells (FBGCs), and the development of fibrosis capsules in the context of FBR are introduced. Additionally, the relationship between various implant materials and FBR is elucidated in detail, as is an overview of the existing approaches and technologies employed to alleviate FBR. Finally, the significance of implant components (metallic materials and non-metallic materials), surface CHEMISTRY (charge and wettability), and physical characteristics (topography, roughness, and stiffness) in establishing the protein "fingerprint" of implant materials is also well documented. In conclusion, this review aims to emphasize the importance of FBR on implant materials and provides the current perspectives and approaches in developing implant materials with anti-FBR properties.

Application of Nondegradable Synthetic Materials for Tendon and Ligament Injury

Tendon and ligament injuries, prevalent requiring surgical intervention, significantly impact joint stability and function. Owing to excellent mechanical properties and biochemical stability, Nondegradable synthetic materials, including polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE), have demonstrated significant potential in the treatment of tendon and ligament injuries. These above materials offer substantial mechanical support, joint mobility, and tissue healing promotion of the shoulder, knee, and ankle joint. This review conclude the latest development and application of nondegradable materials such as artificial patches and ligaments in tendon and ligament injuries including rotator cuff tears (RCTs), anterior cruciate ligament (ACL) injuries, and Achilles tendon ruptures.

High-Performance Implantable Bioelectrodes with Immunocompatible Topography for Modulation of Macrophage Responses

Implantable bioelectrodes enable precise recording or stimulation of electrical signals with living tissues in close contact. However, their performance is frequently compromised owing to inflammatory tissue reactions, which macrophages either induce or resolve by polarizing to an inflammatory (M1) or noninflammatory (M2) phenotype, respectively. Thus, we aimed to fabricate biocompatible and functional implantable conductive polymer bioelectrodes with optimal topography for the modulation of macrophage responses. To this end, we produced heparin-doped polypyrrole (PPy/Hep) electrodes of different surface roughness, with R_a values from 5.5 to 17.6 nm, by varying the charge densities during electrochemical synthesis. In vitro culture revealed that macrophages on rough PPy/Hep electrodes preferentially polarized to noninflammatory phenotypes. In particular, PPy/Hep-900 (R_a = 14 nm) was optimal with respect to electrochemical properties and the suppression of inflammatory M1 polarization. In vivo implantation indicated that PPy/Hep-900 significantly reduced macrophage recruitment, suppressed inflammatory polarization, and mitigated fibrotic tissue formation. In addition, the implanted PPy/Hep-900 electrodes could successfully record electrocardiographic signals for up to 10 days without substantial decreases in sensitivity, while other electrodes substantially lost their signal sensitivity during implantation. Altogether, we demonstrate that modulating the surface features of PPy/Hep can benefit the design and applications of high-performance and high-biocompatibility bioelectrodes.

[Osteoimmunomodulatory effects of inorganic biomaterials in the process of bone repair]

OBJECTIVE

To review the osteoimmunomodulatory effects and related mechanisms of inorganic biomaterials in the process of bone repair.

METHODS

A wide range of relevant domestic and foreign literature was reviewed, the characteristics of various inorganic biomaterials in the process of bone repair were summarized, and the osteoimmunomodulatory mechanism in the process of bone repair was discussed.

RESULTS

Immune cells play a very important role in the dynamic balance of bone tissue. Inorganic biomaterials can directly regulate the immune cells in the body by changing their surface roughness, surface wettability, and other physical and chemical properties, constructing a suitable immune microenvironment, and then realizing dynamic regulation of bone repair.

CONCLUSION

Inorganic biomaterials are a class of biomaterials that are widely used in bone repair. Fully understanding the role of inorganic biomaterials in immunomodulation during bone repair will help to design novel bone immunomodulatory scaffolds for bone repair.

ASIA (Shoenfeld's syndrome) due to hysteroscopic Essure sterilization

Essure (TM, Bayer; Leverkusen, Germany) may act as a potential cause of autoimmune/inflammatory syndrome by adjuvants (ASIA). Essure is a device hysteroscopically inserted into the fallopian tubes to elicit a local inflammatory response for permanent sterilization. Patients with ASIA present with a constellation of symptoms including fatigue, cognitive impairment, and arthralgias. It is well known that ASIA is triggered by implantation of foreign material such as breast implants and mesh for hernia repair. In the current study, we present a retrospective cohort of 33 patients electing to remove Essure due to pelvic pain and systemic symptoms consistent with an ASIA diagnosis, and detail a case report of an Essure patient. Furthermore, we reviewed the existing literature on adverse events associated with Essure and studies assessing outcomes following explantation. The concept that Essure may trigger ASIA is further supported by both in vivo and in vitro studies demonstrating immunostimulatory effects of the material components of the device. We conclude that the existing evidence is sufficient to recommend screening of Essure recipients for ASIA symptoms, and where indicated, discussion of the risks and potential benefits of surgical removal.

Size-Confined Effects of Nanostructures on Fibronectin-Induced Macrophage Inflammation on Titanium Implants

Macrophage activation determines the fate of biomaterials implantation. Though researches have shown that fibronectin (FN) is highly involved in integrin-induced macrophage activation on biomaterials, the mechanism of how nanosized structure affects macrophage behavior is still unknown. Here, titanium dioxide nanotube structures with different sizes are fabricated to investigate the effects of nanostructure on macrophage activation. Compared with larger sized nanotubes and smooth surface, 30 nm nanotubes exhibit considerable lesser pro-inflammatory properties on macrophage differentiation. Confocal protein observation and molecular dynamics simulation show that FN displays conformation changes on different nanotubes in a feature of "size-confined," which causes the hiding of Arg-Gly-Asp (RGD) domain on other surfaces. The matching size of nanotube with FN allows the maximum exposure of RGD on 30 nm nanotubes, activating integrin-mediated focal adhesion kinase (FAK)-phosphatidylinositol-3 kinase γ (PI3Kγ) pathway to inhibit nuclear factor kappa B (NF-κB) signaling. In conclusion, this study explains the mechanism of nanostructural-biological signaling transduction in protein and molecular levels, as well as proposes a promising strategy for surface modification to regulate immune responses on bioimplants.

Role of rhBMP-7, Fibronectin, And Type I Collagen in Dental Implant Osseointegration Process: An Initial Pilot Study on Minipig Animals

Background: The biological factors involved in dental implant osseointegration need to be investigated to improve implant success. Methods: Twenty-four implants were inserted into the tibias of six minipigs. Bone samples were obtained at 7, 14, and 56 days. Biomolecular analyses evaluated mRNA of BMP-4, -7, Transforming Growth Factor-β2, Interleukin-1β, and Osteocalcin in sites treated with rhBMP-7, Type 1 Collagen, or Fibronectin (FN). Inflammation and osteogenesis were evaluated by histological analyses. Results: At 7 and 14 days, BMP-4 and BMP-7 increased in the sites prepared with rhBMP-7 and FN. BMP-7 remained greater at 56 days in rhBMP-7 and FN sites. BPM-4 at 7 and 14 days increased in Type 1 Collagen sites; BMP-7 increased from day 14. FN increased the TGF-β2 at all experimental times, whilst the rhBMP-7 only did so up to 7 days. IL-1β increased only in collagen-treated sites from 14 days. Osteocalcin was high in FN-treated sites. Neutrophilic granulocytes characterized the inflammatory infiltrate at 7 days, and mononuclear cells at 14 and 56 days. Conclusions: This initial pilot study, in a novel way, evidenced that Type 1 Collagen induced inflammation and did not stimulate bone production; conversely FN or rhBMP-7 showed neo-osteogenetic and anti-inflammatory properties when directly added into implant bone site.

The State of the Art and Prospects for Osteoimmunomodulatory Biomaterials

The critical role of the immune system in host defense against foreign bodies and pathogens has been long recognized. With the introduction of a new field of research called osteoimmunology, the crosstalk between the immune and bone-forming cells has been studied more thoroughly, leading to the conclusion that the two systems are intimately connected through various cytokines, signaling molecules, transcription factors and receptors. The host immune reaction triggered by biomaterial implantation determines the in vivo fate of the implant, either in new bone formation or in fibrous tissue encapsulation. The traditional biomaterial design consisted in fabricating inert biomaterials capable of stimulating osteogenesis; however, inconsistencies between the in vitro and in vivo results were reported. This led to a shift in the development of biomaterials towards implants with osteoimmunomodulatory properties. By endowing the orthopedic biomaterials with favorable osteoimmunomodulatory properties, a desired immune response can be triggered in order to obtain a proper bone regeneration process. In this context, various approaches, such as the modification of chemical/structural characteristics or the incorporation of bioactive molecules, have been employed in order to modulate the crosstalk with the immune cells. The current review provides an overview of recent developments in such applied strategies.

Osteo-Compatibility of 3D Titanium Porous Coating Applied by Direct Energy Deposition (DED) for a Cementless Total Knee Arthroplasty Implant: in Vitro and in Vivo Study

Direct energy deposition (DED) technology has gained increasing attention as a new implant surface technology that replicates the porous structure of natural bones facilitating osteoblast colonization and bone ingrowth. However, concerns have arisen over osteolysis or chronic inflammation that could be caused by Cobalt-chrome (CoCr) alloy and Titanium (Ti) nanoparticles produced during the fabrication process. Here, we evaluated whether a DED Ti-coated on CoCr alloy could improve osteoblast colonization and osseointegration in vitro and in vivo without causing any significant side effects. Three types of implant CoCr surfaces (smooth, sand-blasted and DED Ti-coated) were tested and compared. Three cell proliferation markers and six inflammatory cytokine markers were measured using SaOS2 osteoblast cells. Subsequently, X-ray and bone histomorphometric analyses were performed after implantation into rabbit femur. There were no differences between the DED group and positive control in cytokine assays. However, in the 5-bromo-2′-deoxyuridine (BrdU) assay the DED group exhibited even higher values than the positive control. For bone histomorphometry, DED was significantly superior within the 1000 µm bone area. The results suggest that DED Ti-coated metal printing does not affect the osteoblast viability or impair osseointegration in vitro and in vivo. Thus, this technology is biocompatible for coating the surfaces of cementless total knee arthroplasty (TKA) implants.

Titanium Porous Coating Using 3D Direct Energy Deposition (DED) Printing for Cementless TKA Implants: Does It Induce Chronic Inflammation?

Because of the recent technological advances, the cementless total knee arthroplasty (TKA) implant showed satisfactory implant survival rate. Newly developed 3D printing direct energy deposition (DED) has superior resistance to abrasion as compared to traditional methods. However, there is still concern about the mechanical stability and the risk of osteolysis by the titanium (Ti) nanoparticles. Therefore, in this work, we investigated whether DED Ti-coated cobalt-chrome (CoCr) alloys induce chronic inflammation reactions through in vitro and in vivo models. We studied three types of implant surfaces (smooth, sand-blasted, and DED Ti-coated) to compare their inflammatory reaction. We conducted the in vitro effect of specimens using the cell counting kit-8 (CCK-8) assay and an inflammatory cytokine assay. Subsequently, in vivo analysis of the immune profiling, cytokine assay, and histomorphometric evaluation using C57BL/6 mice were performed. There were no significant differences in the CCK-8 assay, the cytokine assay, and the immune profiling assay. Moreover, there were no difference for semi-quantitative histomorphometry analysis at 4 and 8 weeks among the sham, smooth, and DED Ti-coated samples. These results suggest that DED Ti-coated printing technique do not induce chronic inflammation both in vitro and in vivo. It has biocompatibility for being used as a surface coating of TKA implant.

Nanotechnology in regenerative ophthalmology

In recent years, regenerative medicine is gaining momentum and is giving hopes for restoring function of diseased, damaged, and aged tissues and organs and nanotechnology is serving as a catalyst. In the ophthalmology field, various types of allogenic and autologous stem cells have been investigated to treat some ocular diseases due to age-related macular degeneration, glaucoma, retinitis pigmentosa, diabetic retinopathy, and corneal and lens traumas. Nanomaterials have been utilized directly as nanoscaffolds for these stem cells to promote their adhesion, proliferation and differentiation or indirectly as vectors for various genes, tissue growth factors, cytokines and immunosuppressants to facilitate cell reprogramming or ocular tissue regeneration. In this review, we reviewed various nanomaterials used for retina, cornea, and lens regenerations, and discussed the current status and future perspectives of nanotechnology in tracking cells in the eye and personalized regenerative ophthalmology. The purpose of this review is to provide comprehensive and timely insights on the emerging field of nanotechnology for ocular tissue engineering and regeneration.

Hyaluronic Acid Nanoparticle Composite Films Confer Favorable Time-Dependent Biofunctions for Vascular Wound Healing

Vascular stent implantation is the primary treatment for coronary artery disease. Surface modification of coronary stents is a topic of interest to prevent thrombosis and restenosis and to promote endothelization. However, bioactive coatings on implants have not yet been fully developed for the time-ordered biological requirements of vascular stents. The first month after vascular stent implantation, the pathological changes in the injured vascular tissue are complex and time-ordered. Therefore, vascular stents possess time-dependent biofunctions with early phase anticoagulant and anti-inflammatory properties. In the later stage, inhibitory effects on smooth muscle cell proliferation and the promotion of endothelial cell adhesion might meet the requirements of vascular repair. We fabricated three types of hyaluronic acid nanoparticles (HA-NPs) by subjecting HA and poly(ether imide) to ethyl(dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide coupling reaction. The HA-NPs prepared by HA with a molecular weight of 100 kDa showed the best stability in a hyaluronidase environment. HA-NP composite films (HA-NCFs) were then fabricated by coimmobilizing selected HA-NPs (100 kDa) and HA molecules (100 kDa) through amide reaction on PDA/HD coated 316 L stainless steel surfaces. The detachment behavior of HA-NPs (100 kDa) in PBS for 20 days indicated that the HA-NPs (100 kDa) gradually detached from the surface. In vitro tests (anticoagulant and anti-inflammatory tests, endothelial cells, and smooth muscle cells seeding, and bacterial adhesion test) indicated that the newly fabricated HA-NCFs have inhibitory effects on the adhesion of fibrinogen, platelets, macrophages, bacteria, SMCs, and ECs. As the HA-NPs detached from the surface, the HA-NCFs showed excellent gradual comprehensive biocompatibility, which promoted adhesion and proliferation of ECs while still exerting inhibitory effects on the platelets, macrophages, and SMCs. Finally, in vivo SS wire implantation test (aortic implantation in healthy Sprague-Dawley rats) showed that HA-NCFs possessed anti-inflammatory properties, inhibited the proliferation of smooth muscle cells, and promoted re-endothelialization. In particular, HA-NCFs with time-dependent biofunctions showed better antirestenosis effects than those of surfaces modified with molecular HA, which exhibited constant biocompatibility. This study provides an important basis for the construction of HA-NP composite films with favorable time-dependent biofunctions for the time-ordered biological requirements of vascular stent.

Biomaterials: Foreign Bodies or Tuners for the Immune Response?

The perspectives of regenerative medicine are still severely hampered by the host response to biomaterial implantation, despite the robustness of technologies that hold the promise to recover the functionality of damaged organs and tissues. In this scenario, the cellular and molecular events that decide on implant success and tissue regeneration are played at the interface between the foreign body and the host inflammation, determined by innate and adaptive immune responses. To avoid adverse events, rather than the use of inert scaffolds, current state of the art points to the use of immunomodulatory biomaterials and their knowledge-based use to reduce neutrophil activation, and optimize M1 to M2 macrophage polarization, Th1 to Th2 lymphocyte switch, and Treg induction. Despite the fact that the field is still evolving and much remains to be accomplished, recent research breakthroughs have provided a broader insight on the correct choice of biomaterial physicochemical modifications to tune the reaction of the host immune system to implanted biomaterial and to favor integration and healing.

The summary of the most important cell-biomaterial interactions that need to be considered during in vitro biocompatibility testing of bone scaffolds for tissue engineering applications

Tissue engineered products (TEPs), which mean biomaterials containing either cells or growth factors or both cells and growth factors, may be used as an alternative to the autografts taken directly from the bone of the patients. Nevertheless, the use of TEPs needs much more understanding of biointeractions between biomaterials and eukaryotic cells. Despite the possibility of the use of in vitro cellular models for initial evaluation of the host response to the implanted biomaterial, it is observed that most researchers use cell cultures only for the evaluation of cytotoxicity and cell proliferation on the biomaterial surface, and then they proceed to animal models and in vivo testing of bone implants without fully utilizing the scientific potential of in vitro models. In this review, the most important biointeractions between eukaryotic cells and biomaterials were discussed, indicating molecular mechanisms of cell adhesion, proliferation, and biomaterial-induced activation of immune cells. The article also describes types of cellular models which are commonly used for biomaterial testing and highlights the possibilities and drawbacks of in vitro tests for biocompatibility evaluation of novel scaffolds. Finally, the review summarizes recent findings concerning the use of adult mesenchymal stem cells for TEP generation and compares the potential of bone marrow- and adipose tissue-derived stem cells in regenerative medicine applications.

Multifunctional coatings that mimic the endothelium: surface bound active heparin nanoparticles with in situ generation of nitric oxide from nitrosothiols

Multifunctional coatings that mimic the endothelial function in terms of nitric oxide generation and membrane-bound active heparin species are prepared via the immobilization of cystamine-modified heparin/polyethyleneimine (Hep-Cys/PEI) nanoparticles. Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS) were conducted to confirm the coating formation. Functions of active heparin release and nitric oxide (NO) generation are obtained on the material surface after the immobilization of Hep-Cys/PEI nanoparticles. Moreover, a nanoparticle-immobilized coating is sufficiently flexible to resist the deformation of a 316L SS stent without any destruction. With the introduction of heparin, the antithrombin III (AT-III) binding ability was significantly enhanced with prolonged APTT time. Besides, a Hep-Cys/PEI nanoparticle immobilized coating surface not only significantly suppressed the platelet adhesion and activation, but also promoted EC proliferation and inhibited SMC proliferation. Besides, a milder tissue response was observed on the NP immobilized surface. With the synergistic effect of heparin and nitric oxide generating moieties, such multifunctional coatings presented potential for the modification of vascular materials.

Design, preparation and performance of a novel drug-eluting stent with multiple layer coatings

Drug-eluting stents (DESs) can effectively control the harmful effects of coronary artery disease, because of their excellent ability to reduce in-stent restenosis. However, delayed re-endothelialization and late stent thrombosis have caused concern over the safety of DESs. In this study, according to time-ordered pathological responses after stent implantation, a hierarchical multiple drug-eluting stent was designed and prepared to overcome the existing DES limitations. A platelet membrane glycoprotein IIIa monoclonal antibody (SZ-21) and a vascular endothelial growth factor (VEGF₁₂₁) were loaded into the inner coating of 316L stainless steel (316L SS) stents to inhibit thrombosis and promote re-endothelialization; rapamycin (RAPA) was loaded into the third layer to inhibit intima hyperplasia; a drug-free poly-l-lactic acid coating was located on the second and fourth layers and used as sustained release layers. The results showed that the three drugs exhibited sequential release kinetics without significant burst release. RAPA released quickly at the early stage, while SZ-21 and VEGF₁₂₁ achieved a slow and prolonged release. In vitro experiments showed that the stents had excellent hemocompatibility and anti-inflammatory properties, and promoted the proliferation and migration of endothelial cells while inhibiting the proliferation and migration of smooth muscle cells. Finally the stents were implanted in the carotid arteries of New Zealand white rabbits. In vivo results showed that compared to 316L SS stents, the multiple drug-eluting stents could accelerate re-endothelialization and inhibit thrombosis, inflammation and in-stent restenosis after 4 weeks (12.79 ± 2.45% vs. 25.27 ± 4.81%) and 12 weeks (15.87 ± 3.62% vs. 58.84 ± 6.87%). These results indicate that the novel drug-eluting stent with multiple layer coatings will have a highly potential clinical application.

Fabrication of a blood compatible composite membrane from chitosan nanoparticles, ethyl cellulose and bacterial cellulose sulfate

A heparin-like composite membrane was fabricated through electrospinning chitosan nanoparticles (CN) together with an ethylcellulose (EC) ethanol solution onto a bacterial cellulose sulfate membrane (BCS). Scanning electron microscopy images revealed that there were no chitosan particles in the obtained composite CN-EC/BCS membranes (CEB), indicating CN had been stretched to nanofibers. X-ray photoelectron spectroscopy verified the existence of –NH₂ from chitosan and –SO₃⁻ from BCS on the surface of CEB membranes. Positively charged CN in the electrospinning solution and negatively charged BCS on the collector increased the electrostatic force and the electrospinning ability of the EC was increased. The membrane was hydrophobic, with a water contact angle higher than 120°. CEB membranes expressed good blood compatibility according to the results of coagulation time and platelet adhesion experiments. No platelets adhered on the surface of the CEB membranes. An inflammatory response was investigated according to activation of the macrophages seeded onto the membranes. Macrophages seeded on CEB membranes are not activated after 24 h incubation.

A blood compatible membrane was fabricated through electrospinning a solution of chitosan nanoparticles and ethylcellulose onto a bacterial cellulose sulfate membrane to mimic heparin's structure.

In Vitro Effect of 3D Plates Used for Surgical Treatment of Condylar Fractures on Prostaglandin E₂ (PGE₂) and Thromboxane B₂ (TXB₂) Concentration in THP-1 Macrophages

Recent studies have shown promising results concerning the effectiveness of 3D plates in terms of stabilization of condylar fractures. Despite the use of new techniques and new materials, we can still observe certain side effects, including the immune reaction of the body, which may lead to the excessive inflammation. The aim of this paper was to determine how the production of prostaglandin E₂ (PGE₂) and thromboxane B₂ (TXB₂) in THP-1 monocytes/macrophages is influenced by the titanium 3D plates and dedicated screws. The experiments were conducted on THP-1 monocytic cell line and macrophages derived from a THP-1cells. The concentrations of PGE₂ and TXB₂ released were measured by using immunoassay kit. Verification of plate-induced activation of THP-1 monocytes and macrophages and initiation of inflammatory reaction was conducted by flow cytometry. Despite some differences in the content of the implant devices our results showed that these plates did not statistically significantly increase the production of these prostanoids. Osteosynthesis of condylar fractures using 3D titanium mini-plates seems to be a good alternative to traditional plates due to their lack of stimulating the cyclooxygenase-dependent production of prostanoids; limiting the development of inflammatory reactions.

Investigation of enhanced hemocompatibility and tissue compatibility associated with multi-functional coating based on hyaluronic acid and Type IV collagen

The biocompatibility of cardiovascular devices has always been considered crucial for their clinical efficacy. Therefore, a biofunctional coating composed of Type IV collagen (CoIV) and hyaluronan (HA) was previously fabricated onto the titanium (Ti) substrate for the application of promoting vascular smooth muscle cell contractile phenotype and improving surface endothelialization. However, the anti-inflammation property, blood compatibility and in vivo tissue compatibility of the HA/CoIV coating, as paramount consideration of cardiovascular materials surface coating, have not been investigated. Thus, in this study, the three crucial properties of the HA/CoIV coating were tested. The platelet adhesion/activation test and the dynamic whole blood experiment implied that the HA/CoIV coating had better blood compatibility compared with Ti substrate and pure CoIV coating. The macrophage adhesion/activation and inflammatory cytokine release (tumor necrosis factor-alpha and interleukin-1) results indicated that the HA/CoIV coating could significantly improve the anti-inflammation property of the Ti substrate. The in vivo implantation of SD rats for 3 weeks' results demonstrated that the HA/CoIV coating caused milder tissue response. All these results suggested that the multi-functional HA/CoIV coating possessed good biocompatibility. This research is anticipated to be potentially applied for the surface modification of cardiovascular stents.

Multifunctional Coating Based on Hyaluronic Acid and Dopamine Conjugate for Potential Application on Surface Modification of Cardiovascular Implanted Devices

Surface modification by conjugating biomolecules has been widely proved to enhance biocompatibility of cardiovascular implanted devices. Here, we aimed at developing a multifunctional surface that not only provides good hemocompatibility but also functions well in inducing desirable vascular cell-material interaction. In the present work, the multicoatings of hyaluronic acid (HA) and dopamine (PDA) were prepared onto 316L stainless steel (316L SS) via chemical conjugation (Michael addition, Schiff base reaction, and electrostatic adsorption). The results of platelet adhesion and activation and the whole blood tests indicated that the HA/PDA coatings obtained better hemocompatibility compared with the bare 316L SS and HA or PDA immobilized on 316L SS. The HA/PDA coatings also inhibited the proliferation of smooth muscle cells and adhesion/activation of macrophages effectively, whereas not all the HA/PDA coatings improved surface endothelialization rapidly and the effects of the multifunctional coatings on endothelial cell growth depend on the HA amounts (1.0, 2.0, and 5.0 mg/mL, labeled as PDA-HA-1, PDA-HA-2, and PDA-HA-5 respectively). Herein the PDA-HA-1 and PDA-HA-2 coatings were found to improve endothelial cell adhesion and proliferation significantly. The tissue compatibility of the HA/PDA coatings also depends on the HA amounts, and the PDA-HA-2 coating was proved to cause milder in vivo tissue response. Additionally, the mechanism of the HA molecular weight change and in vivo tissue response was also explored. These results effectively suggested that the HA/PDA coating might be promising when serving as a cardiovascular implanted device coating.

A comparison of adsorbed and grafted fibronectin coatings under static and dynamic conditions

Coatings for medical devices are expected to improve their surface biocompatibility mainly by being bioactive, i.e. stimulating healing-oriented interactions with living cells, tissues and organs.

In vitro evaluation of the risk of inflammatory response after chitosan/HA and chitosan/β-1,3-glucan/HA bone scaffold implantation

The aim of the study was to evaluate in vitro the risk of inflammatory response induced by chitosan/hydroxyapatite (chit/HA) and novel chitosan/β-1,3-glucan/hydroxyapatite (chit/glu/HA) bone scaffolds. The inflammatory response was assessed via measurement of proinflammatory cytokine and ROI production by human monocytes, macrophages, and osteoblasts stimulated with investigated scaffolds. Moreover, adsorption of human serum/plasma proteins to the tested materials was determined. Both biomaterials did not induce intracellular ROI generation by monocytes, macrophages, and osteoblasts and did not stimulate proinflammatory cytokine (IL-6 and TNF-α) production by inflammatory cells. Moreover, the chit/glu/HA material induced increased TNF-α production by osteoblasts that is believed to enhance osteogenic differentiation. Thus, it was demonstrated that chit/HA and chit/glu/HA scaffolds carry a low risk of biomaterial-induced inflammatory response and are promising materials as bone scaffolds for bone tissue engineering and regenerative medicine applications.

Sequential delivery of BMP-2 and BMP-7 for bone regeneration using a heparinized collagen membrane

To investigate the effect of the sequential delivery of bone morphogenetic proteins BMP-2 and BMP-7 on bone regeneration in rat calvarial defects (40 Sprague-Dawley rats, 8mm defect size), all animals were treated with a hydroxyapatite (HA)/tricalcium phosphate (TCP) bone graft covered with a collagen membrane. The experimental groups were as follows: (1) control group: unmodified collagen (no treatment); (2) BMP-2 group: 5 μg of BMP-2; (3) hep-BMP-7 group: 5 μg BMP-7 chemically bound to heparinized collagen; and (4) BMP-2/hep-BMP-7 group: 2.5 μg BMP-7 bound to heparinized collagen and subsequently treated with 2.5 μg BMP-2. Defect healing was examined at 2 and 8 weeks after surgery. The BMP-2 group showed the largest new bone area at week 2 (29.3 ± 7.3%; P = 0.009); new bone areas in the hep-BMP-7 and BMP-2/hep-BMP-7 groups were similar (11.8 ± 3.4% and 12.9 ± 5.71%, respectively; P = 0.917). After 8 weeks, the BMP-2/hep-BMP-7 group showed the largest new bone area (43.3 ± 6.2%), followed by the BMP-2 and hep-BMP-7 groups (P = 0.013). Accordingly, in comparison with single deliveries of BMP-2 and BMP-7, sequential delivery of BMP-2 and BMP-7 using a heparinized collagen membrane significantly induced new bone formation with a smaller quantity of BMP-2 in rat calvarial defects.

Sulfated glycans in inflammation

Sulfated glycans such as glycosaminoglycans on proteoglycans are key players in both molecular and cellular events of inflammation. They participate in leukocyte rolling along the endothelial surface of inflamed sites; chemokine regulation and its consequential functions in leukocyte guidance, migration and activation; leukocyte transendothelial migration; and structural assembly of the subendothelial basement membrane responsible to control tissue entry of cells. Due to these and other functions, exogenous sulfated glycans of various structures and origins can be used to interventionally down-regulate inflammation processes. In this review article, discussion is given primarily on the anti-inflammatory functions of mammalian heparins, heparan sulfate, chondroitin sulfate, dermatan sulfate and related compounds as well as the holothurian fucosylated chondroitin sulfate and the brown algal fucoidans. Understanding the underlying mechanisms of action of these sulfated glycans in inflammation, helps research programs involved in developing new carbohydrate-based drugs aimed to combat acute and chronic inflammatory disorders.

Does mechanical filtration of intraoperative cell salvage effectively remove titanium debris generated during instrumented spinal surgery? An in vitro analysis

BACKGROUND CONTEXT

Instrumented fusion of the spine is a surgery commonly performed to stabilize vertebrae causing pain and to correct anatomic deformities. Such surgery can create substantial blood loss. Autotransfusion is a means to limit homologous blood transfusion in this setting. However, a dilemma is created when the high-speed drill used for bone removal comes in contact with implanted titanium spinal hardware. A clinician at this point is forced to decide between two options: to discontinue autotransfusion to avoid the potential transfusion of titanium fragments while risking blood loss and the need for homologous transfusion or to continue autotransfusion while risking transfusion of titanium fragments back into circulation.

PURPOSE

To conclusively identify whether titanium fragments created by a high-speed drill are able to pass through standard autotransfusion microaggregate blood filters.

STUDY DESIGN

A positive and negatively controlled experiment with blinded sample analysis.

OUTCOMES MEASURES

The presence or absence of titanium alloy on a filter with detection by energy-dispersive X-ray spectroscopy (EDX).

METHODS

A mock autotransfusion setup was devised for in vitro filtering. Six investigational and two control experiments were conducted. Titanium fragments generated by a high-speed drill were aspirated with saline and filtered with standard autotransfusion reservoirs and microaggregate blood filters. A final filter with a 1-μm pore size was placed distal to the blood filters. After filtration was complete, this final filter was analyzed using EDX.

RESULTS

The presence of titanium was confirmed by EDX on five of six investigational filters. The positive and negative control filters were analyzed by EDX and tested positive and negative, respectively, for titanium.

CONCLUSIONS

Standard 40 μm reservoir and blood microaggregate filters do not eliminate the smallest fragments of titanium generated by contact between a high-speed drill and a titanium hardware. The mass of titanium able to elude filtration is very small. The impact of transfusing blood contaminated with such a small mass of titanium is not known.

Surface modification with dopamine and heparin/poly-L-lysine nanoparticles provides a favorable release behavior for the healing of vascular stent lesions

Surface biofunctional modification of coronary artery stents to prevent thrombosis and restenosis formation, as well as accelerate endothelialization, has become a new hot spot. However, bioactive coatings on implants are not yet sufficiently developed for long-term activity, as they quickly lose efficiency in vivo and finally fail. On the basis of a novel time-ordered concept of biofunctionality for vascular stents, heparin/poly l-lysine nanoparticle (NP) was developed and immobilized on a polydopamine-coated titanium surface, with the aim of regulating and maintaining the intravascular biological response within the normal range after biomaterial implantation. An in vitro dynamic release model was established to mimic the blood flow condition in vivo with three phases: (1) An early phase (1-7 days) with release of predominantly anticoagulant and anti-inflammatory substances and to a minor degree antiproliferative effects against smooth muscle cells (SMCs); (2) this is followed by a phase (7-14 days) of supported endothelial cell (ECs) proliferation and suppressed SMC proliferation with persisting high antithrombogenicity and anti-inflammatory properties of the surface. (3) Finally, a stable stage (14-28 days) with adequate biomolecules on the surface that maintain hemocompatibility and anti inflammation as well as inhibit SMCs proliferation and promote ECs growth. In vivo animal tests further confirmed that the NP-modified surface provides a favorable release behavior to apply a stage-adjusted remedy. We suggested that these observations provide important guidance and potential means for reasonable and suitable platform construction on a stent surface.

Polysaccharides as Cell Carriers for Tissue Engineering: the Use of Cellulose in Vascular Wall Reconstruction

Polysaccharides are long carbohydrate molecules of monosaccharide units joined together by glycosidic bonds. These biological polymers have emerged as promising materials for tissue engineering due to their biocompatibility, mostly good availability and tailorable properties. This complex group of biomolecules can be classified using several criteria, such as chemical composition (homo- and heteropolysaccharides), structure (linear and branched), function in the organism (structural, storage and secreted polysaccharides), or source (animals, plants, microorganisms). Polysaccharides most widely used in tissue engineering include starch, cellulose, chitosan, pectins, alginate, agar, dextran, pullulan, gellan, xanthan and glycosaminoglycans. Polysaccharides have been applied for engineering and regeneration of practically all tissues, though mostly at the experimental level. Polysaccharides have been tested for engineering of blood vessels, myocardium, heart valves, bone, articular and tracheal cartilage, intervertebral discs, menisci, skin, liver, skeletal muscle, neural tissue, urinary bladder, and also for encapsulation and delivery of pancreatic islets and ovarian follicles. For these purposes, polysaccharides have been applied in various forms, such as injectable hydrogels or porous and fibrous scaffolds, and often in combination with other natural or synthetic polymers or inorganic nanoparticles. The immune response evoked by polysaccharides is usually mild, and can be reduced by purifying the material or by choosing appropriate crosslinking agents.

Electrochemical modulation of plasma fibronectin surface conformation enables filament formation and control of endothelial cell–surface interactions

Electrochemical modulation of a gold surface charge induces conformational changes in fibronectin when immobilized on the surface. A negatively-charged surface yields an open and filamentous fibronectin which significantly improves endothelial cell adhesion.

Orbital adherence with titanium mesh floor implants: a review of 10 cases

BACKGROUND

Multiple materials have been used in the repair of orbital floor fractures. We report 10 cases of complications relating to the use of titanium mesh orbital floor implants.

METHOD

A retrospective review of 10 cases in 2 centres in New Zealand. Patients presented with diplopia or eyelid retraction following repair of an orbital floor fracture with titanium mesh implants.

RESULTS

Ten patients (7 male, 3 female) aged between 15-78 years old (mean 39 years) presented with significant restriction of eye movement and/or eyelid retraction following repair of an orbital floor fracture with a titanium mesh implant. Seven patients presented with restriction of eye movement alone. Three patients had lower lid retraction in addition to restriction of eye movement. One patient presented with epiphora following erosion of the implant through the nasolacrimal duct. Seven patients underwent surgical removal of the implant with all patients showing improvement of extraocular movement post-operatively. Three cases did not undergo implant removal with one case showing mild improvement over 9 months, and 2 cases showing no improvement. The mean interval between the initial surgery and removal of the implant was 7.1 months.

DISCUSSION

In our series, 7 cases required explantation of the original titanium implant. In these cases a vigorous fibrotic reaction had taken place between the orbital contents and the titanium mesh implant. We postulate that the fibrous reaction between the implant and the orbital contents caused the eye movement restriction and the lid retraction. Implant materials used in orbital floor fracture surgery should be inert with a flat profile rather than a mesh to prevent adhesions through the mesh that may cause cicatricial eye movement restriction and eyelid retraction.