The Quest for Anti-inflammatory and Anti-infective Biomaterials in Clinical Translation

Azithromycin-carrying and microtubule-orientated biomimetic poly (lactic-co-glycolic acid) scaffolds for eyelid reconstruction

Introduction

Tarsal plate repair is the major challenge of eyelid reconstruction for the oculoplastic surgeon. The ideal synthetic tarsal plate substitute should imitate the microstructure and mechanical strength of the natural eyelid. The aim of this work was to develop a novel bionic substitute for eyelid reconstruction.

Methods

Three types of poly(lactic-co-glycolic acid) (PLGA) scaffolds (random, oriented, and azithromycin-loaded oriented scaffolds) were prepared using an improved thermal-induced phase separation technique. The microstructure of the scaffolds was examined by scanning electron microscopy. In vitro cytotoxicity was assessed using scaffold extracts. Fibroblast and primary rat meibomian gland epithelial cells (rMGCs) were cultured within the scaffolds, and their behavior was observed using fluorescence staining. Three types of PLGA scaffolds were implanted into rabbit eyelid defect in vivo to evaluate their inductive tissue repair function.

Results

We successfully fabricated three types of PLGA scaffolds with varying pore architectures, and the axially aligned scaffold demonstrated interconnected and vertically parallel channels. In vitro cytotoxicity tests using scaffold extracts revealed no apparent cytotoxicity. Fluorescence staining showed that both Fibroblast and rMGCs could adhere well onto the pore walls, with fibroblast elongating along the axially aligned porous structure. At 8 weeks post-implantation, all scaffolds were well integrated by fibrovascular tissue. The axially aligned scaffold groups exhibited faster degradation compared to the random scaffold group, with smaller fragments surrounded by mature collagen fibers.

Conclusion

The study found that the axially aligned scaffolds could well support and guide cellular activities in vitro and in vivo. Moreover, the axially aligned scaffold group showed a faster degradation rate with a matched integration rate compared to the random scaffold group. The findings suggest that the oriented scaffold is a promising alternative for eyelid tarsal plate substitutes.

Self-assembling peptides as immunomodulatory biomaterials

Self-assembling peptides are a type of biomaterial rapidly emerging in the fields of biomedicine and material sciences due to their promise in biocompatibility and effectiveness at controlled release. These self-assembling peptides can form diverse nanostructures in response to molecular interactions, making them versatile materials. Once assembled, the peptides can mimic biological functions and provide a combinatorial delivery of therapeutics such as cytokines and drugs. These self-assembling peptides are showing success in biomedical settings yet face unique challenges that must be addressed to be widely applied in the clinic. Herein, we describe self-assembling peptides' characteristics and current applications in immunomodulatory therapeutics.

A microfluidic-based approach to investigate the inflammatory response of macrophages to pristine and drug-loaded nanostructured hydroxyapatite

The in vitro biological characterization of biomaterials is largely based on static cell cultures. However, for highly reactive biomaterials such as calcium-deficient hydroxyapatite (CDHA), this static environment has limitations. Drastic alterations in the ionic composition of the cell culture medium can negatively affect cell behavior, which can lead to misleading results or data that is difficult to interpret. This challenge could be addressed by a microfluidics-based approach (i.e. on-chip), which offers the opportunity to provide a continuous flow of cell culture medium and a potentially more physiologically relevant microenvironment. The aim of this work was to explore microfluidic technology for its potential to characterize CDHA, particularly in the context of inflammation. Two different CDHA substrates (chemically identical, but varying in microstructure) were integrated on-chip and subsequently evaluated. We demonstrated that the on-chip environment can avoid drastic ionic alterations and increase protein sorption, which was reflected in cell studies with RAW 264.7 macrophages. The cells grown on-chip showed a high cell viability and enhanced proliferation compared to cells maintained under static conditions. Whereas no clear differences in the secretion of tumor necrosis factor alpha (TNF-α) were found, variations in cell morphology suggested a more anti-inflammatory environment on-chip. In the second part of this study, the CDHA substrates were loaded with the drug Trolox. We showed that it is possible to characterize drug release on-chip and moreover demonstrated that Trolox affects the TNF-α secretion and morphology of RAW 264.7 ​cells. Overall, these results highlight the potential of microfluidics to evaluate (bioactive) biomaterials, both in pristine form and when drug-loaded. This is of particular interest for the latter case, as it allows the biological characterization and assessment of drug release to take place under the same dynamic in vitro environment.

Antibacterial Effect of Pre-constructed 3D Bone Scaffolds before and after Modification with Propolis

AIM: This study was to determine and compare the antibacterial activity of different scaffold materials before and after their modification with ethanolic extract of Egyptian propolis ethanolic extract of propolis (EEP). SETTINGS AND DESIGN: Preparation of the dry mass of propolis, preparation of EEP, preparation of the scaffolds, and antibacterial activity testing. MATERIALS AND METHODS: Four bacterial strains were used to determine the antibacterial activity of two different scaffold materials before and after their modification with EEP (15% and 25% by weight). RESULTS: Tricalcium phosphate + gelatin binder modified by 25% EEP exhibited the highest antibacterial activity against Escherichia coli. While, tricalcium phosphate + (alginate and cellulose nanowhiskers) binder modified by 25% EEP demonstrated the highest antibacterial activity Staphylococcus aureus, Streptococcus mutans, and Lactobacillus casei. CONCLUSIONS: It can be concluded that EEP had a significant effect on the antibacterial activity of both scaffold materials; the antibacterial activity was higher against Gram-positive bacteria.

Titanate nanoribbon-based nanobiohybrid for potential applications in regenerative medicine

Nanoparticles capable of mimicking natural tissues represent a major technological advancement in regenerative medicine. In this pilot study, the development of a new nanohybrid composed of titanate nanoribbons to mimic the extracellular matrix is reported. During the first phase, nanoribbons were synthesized by hydrothermal treatment. Subsequently, titanate nanoribbons were functionalized by heterobifunctional polyethylene-glycol (PEG) to graft type I collagen on their surface. Biological properties of this new nanobiohybrid such as cytotoxicity to cardiac cells and platelet aggregation ability were evaluated. The so-formed nanobiohybrid permits cellular adhesion and proliferation favoring fine cardiac tissue healing and regeneration.

Titanate nanoribbons functionalized by heterobifunctional polymer and type I collagen for cellular adhesion and proliferation. This new nanobiohybrid affected neither cytotoxicity nor platelet aggregation ability.

A Review on Biphasic Calcium Phosphate Materials Derived from Fish Discards

This review summarizes the results reported on the production of biphasic calcium phosphate (BCP) materials derived from fish wastes (i.e., heads, bones, skins, and viscera), known as fish discards, and offers an in-depth discussion on their promising potential for various applications in many fields, especially the biomedical one. Thus, considerable scientific and technological efforts were recently focused on the capability of these sustainable materials to be transformed into economically attractive and highly valuable by-products. As a consequence of using these wastes, plenty of beneficial social effects, with both economic and environmental impact, will arise. In the biomedical field, there is a strong and continuous interest for the development of innovative solutions for healthcare improvement using alternative materials of biogenic origin. Thus, the orthopedic field has witnessed a significant development due to an increased demand for a large variety of implants, grafts, and/or scaffolds. This is mainly due to the increase of life expectancy and higher frequency of bone-associated injuries and diseases. As a consequence, the domain of bone-tissue engineering has expanded to be able to address a plethora of bone-related traumas and to deliver a viable and efficient substitute to allografts or autografts by combining bioactive materials and cells for bone-tissue ingrowth. Among biomaterials, calcium phosphate (CaP)-based bio-ceramics are widely used in medicine, in particular in orthopedics and dentistry, due to their excellent bioactive, osteoconductive, and osteointegrative characteristics. Recently, BCP materials (synthetic or natural), a class of CaP, which consist of a mixture of two phases, hydroxyapatite (HA) and beta tricalcium phosphate (β-TCP), in different concentrations, gained increased attention due to their superior overall performances as compared to single-phase formulations. Moreover, the exploitation of BCP materials from by-products of fish industry was reported to be a safe, cheap, and simple procedure. In the dedicated literature, there are many reviews on synthetic HA, β-TCP, or BCP materials, but to the best of our knowledge, this is the first collection of results on the effects of processing conditions on the morphological, compositional, structural, mechanical, and biological properties of the fish discard-derived BCPs along with the tailoring of their features for various applications.

PCL and PCL/bioactive glass biomaterials as carriers for biologically active polyphenolic compounds: Comprehensive physicochemical and biological evaluation

In this work, polymeric and bioactive glass (BG)-modified composite films were successfully loaded with polyphenols (PPh) extracted from sage. It was hypothesized that PPh, alone and in combination with BGs particles, would affect physicochemical and biological properties of the films. Furthermore, sol-gel-derived BG particles would serve as an agent for control the release of the polyphenolic compounds, and other important properties related to the presence of PPh. The results showed that polyphenolic compounds significantly modified numerous material properties and also acted as biologically active substances. On the one hand, PPh can be considered as plasticizers for PCL, on the other hand, they can act as coupling agent in composite materials, improving their mechanical performance. The presence of PPh in materials improved their hydrophilicity and apatite-forming ability, and also provided antioxidant activity. What is important is that the aforementioned properties and kinetics of PPh release can be modulated by the use of various concentrations of PPh, and by the modification of PCL matrix with sol-gel-derived BG particles, capable of binding PPh. The films containing the lowest concentration of PPh exhibited cytocompatibility, significantly increased alkaline phosphatase activity and the expression of bone extracellular matrix proteins (osteocalcin and osteopontin) in human normal osteoblasts, while they reduced intracellular reactive oxygen species production in macrophages. Furthermore, materials loaded with PPh showed antibiofilm properties against Gram positive and Gram negative bacteria. The results suggest that obtained materials represent potential multifunctional biomaterials for bone tissue engineering with a wide range of tunable properties.

Biosensing surfaces and therapeutic biomaterials for the central nervous system in COVID-19

COVID-19 can affect the central nervous system (CNS) indirectly by inflammatory mechanisms and even directly enter the CNS. Thereby, COVID-19 can evoke a range of neurosensory conditions belonging to infectious, inflammatory, demyelinating, and degenerative classes. A broad range of non-specific options, including anti-viral agents and anti-inflammatory protocols, is available with varying therapeutic. Due to the high mortality and morbidity in COVID-19-related brain damage, some changes to these general protocols, however, are necessary for ensuring the delivery of therapeutic(s) to the specific components of the CNS to meet their specific requirements. The biomaterials approach permits crossing the blood-brain barrier (BBB) and drug delivery in a more accurate and sustained manner. Beyond the BBB, drugs can protect neural cells, stimulate endogenous stem cells, and induce plasticity more effectively. Biomaterials for cell delivery exist, providing an efficient tool to improve cell retention, survival, differentiation, and integration. This paper will review the potentials of the biomaterials approach for the damaged CNS in COVID-19. It mainly includes biomaterials for promoting synaptic plasticity and modulation of inflammation in the post-stroke brain, extracellular vesicles, exosomes, and conductive biomaterials to facilitate neural regeneration, and artificial nerve conduits for treatment of neuropathies. Also, biosensing surfaces applicable to the first sensory interface between the host and the virus that encourage the generation of accelerated anti-viral immunity theoretically offer hope in solving COVID-19.

Biomedical optical fibers

Optical fibers with the ability to propagate and transfer data via optical signals have been used for decades in medicine. Biomaterials featuring the properties of softness, biocompatibility, and biodegradability enable the introduction of optical fibers' uses in biomedical engineering applications such as medical implants and health monitoring systems. Here, we review the emerging medical and health-field applications of optical fibers, illustrating the new wave for the fabrication of implantable devices, wearable sensors, and photodetection and therapy setups. A glimpse of fabrication methods is also provided, with the introduction of 3D printing as an emerging fabrication technology. The use of artificial intelligence for solving issues such as data analysis and outcome prediction is also discussed, paving the way for the new optical treatments for human health.

Fish Bone Derived Bi-Phasic Calcium Phosphate Coatings Fabricated by Pulsed Laser Deposition for Biomedical Applications

We report on new biomaterials with promising bone and cartilage regeneration potential, from sustainable, cheap resources of fish origin. Thin films were fabricated from fish bone-derived bi-phasic calcium phosphate targets via pulsed laser deposition with a KrF * excimer laser source (λ = 248 nm, τ_FWHM ≤ 25 ns). Targets and deposited nanostructures were characterized by SEM and XRD, as well as by Energy Dispersive X-ray (EDX) and FTIR spectroscopy. Films were next assessed in vitro by dedicated cytocompatibility and antimicrobial assays. Films were Ca-deficient and contained a significant fraction of β-tricalcium phosphate apart from hydroxyapatite, which could contribute to an increased solubility and an improved biocompatibility for bone regeneration applications. The deposited structures were biocompatible as confirmed by the lack of cytotoxicity on human gingival fibroblast cells, making them promising for fast osseointegration implants. Pulsed laser deposition (PLD) coatings inhibited the microbial adhesion and/or the subsequent biofilm development. A persistent protection against bacterial colonization (Escherichia coli) was demonstrated for at least 72 h, probably due to the release of the native trace elements (i.e., Na, Mg, Si, and/or S) from fish bones. Progress is therefore expected in the realm of multifunctional thin film biomaterials, combining antimicrobial, anti-inflammatory, and regenerative properties for advanced implant coatings and nosocomial infections prevention applications.

Current Trends in Fabrication of Biomaterials for Bone and Cartilage Regeneration: Materials Modifications and Biophysical Stimulations

The aim of engineering of biomaterials is to fabricate implantable biocompatible scaffold that would accelerate regeneration of the tissue and ideally protect the wound against biodevice-related infections, which may cause prolonged inflammation and biomaterial failure. To obtain antimicrobial and highly biocompatible scaffolds promoting cell adhesion and growth, materials scientists are still searching for novel modifications of biomaterials. This review presents current trends in the field of engineering of biomaterials concerning application of various modifications and biophysical stimulation of scaffolds to obtain implants allowing for fast regeneration process of bone and cartilage as well as providing long-lasting antimicrobial protection at the site of injury. The article describes metal ion and plasma modifications of biomaterials as well as post-surgery external stimulations of implants with ultrasound and magnetic field, providing accelerated regeneration process. Finally, the review summarizes recent findings concerning the use of piezoelectric biomaterials in regenerative medicine.

The Role of the Chemokine System in Tissue Response to Prosthetic By-products Leading to Periprosthetic Osteolysis and Aseptic Loosening

Millions of total joint replacements are performed annually worldwide, and the number is increasing every year. The overall proportion of patients achieving a successful outcome is about 80–90% in a 10–20-years time horizon postoperatively, periprosthetic osteolysis (PPOL) and aseptic loosening (AL) being the most frequent reasons for knee and hip implant failure and reoperations. The chemokine system (chemokine receptors and chemokines) is crucially involved in the inflammatory and osteolytic processes leading to PPOL/AL. Thus, the modulation of the interactions within the chemokine system may influence the extent of PPOL. Indeed, recent studies in murine models reported that (i) blocking the CCR2–CCL2 or CXCR2–CXCL2 axis or (ii) activation of the CXCR4–CXCL12 axis attenuate the osteolysis of artificial joints. Importantly, chemokines, inhibitory mutant chemokines, antagonists of chemokine receptors, or neutralizing antibodies to the chemokine system attached to or incorporated into the implant surface may influence the tissue responses and mitigate PPOL, thus increasing prosthesis longevity. This review summarizes the current state of the art of the knowledge of the chemokine system in human PPOL/AL. Furthermore, the potential for attenuating cell trafficking to the bone–implant interface and influencing tissue responses through modulation of the chemokine system is delineated. Additionally, the prospects of using immunoregenerative biomaterials (including chemokines) for the prevention of failed implants are discussed. Finally, this review highlights the need for a more sophisticated understanding of implant debris-induced changes in the chemokine system to mitigate this response effectively.