A biomimetic collagen/heparin multi-layered porous hydroxyapatite orbital implant for in vivo vascularization studies on the chicken chorioallantoic membrane

Protein-based layer-by-layer films for biomedical applications

The surface engineering of biomaterials is crucial for their successful (bio)integration by the body, i.e. the colonization by the tissue-specific cell, and the prevention of fibrosis and/or bacterial colonization. Performed at room temperature in an aqueous medium, the layer-by-layer (LbL) coating method is based on the alternating deposition of macromolecules. Versatile and simple, this method allows the functionalization of surfaces with proteins, which play a crucial role in several biological mechanisms. Possessing intrinsic properties (cell adhesion, antibacterial, degradable, etc.), protein-based LbL films represent a powerful tool to control bacterial and mammalian cell fate. In this article, after a general introduction to the LbL technique, we will focus on protein-based LbL films addressing different biomedical issues/domains, such as bacterial infection, blood contacting surfaces, mammalian cell adhesion, drug and gene delivery, and bone and neural tissue engineering. We do not consider biosensing applications or electrochemical aspects using specific proteins such as enzymes.

The Use of Functional Biomaterials in Aesthetic and Functional Restoration in Orbital Surgery

The integration of functional biomaterials in oculoplastic and orbital surgery is a pivotal area where material science and clinical practice converge. This review, encompassing primary research from 2015 to 2023, delves into the use of biomaterials in two key areas: the reconstruction of orbital floor fractures and the development of implants and prostheses for anophthalmic sockets post-eye removal. The discussion begins with an analysis of orbital floor injuries, including their pathophysiology and treatment modalities. It is noted that titanium mesh remains the gold standard for orbital floor repair due to its effectiveness. The review then examines the array of materials used for orbital implants and prostheses, highlighting the dependence on surgeon preference and experience, as there are currently no definitive guidelines. While recent innovations in biomaterials show promise, the review underscores the need for more clinical data before these new materials can be widely adopted in clinical settings. The review advocates for an interdisciplinary approach in orbital surgery, emphasizing patient-centered care and the potential of biomaterials to significantly enhance patient outcomes.

Biological activity of a vascular endothelial cell-hydroxyapatite orbital implant complex: An experimental study

The reduction in postoperative complications is a considerable concern after orbital reparation and reconstruction. Selecting the appropriate scaffold materials to improve the survival rates of the seeded cells is a challenge in tissue engineering. The aim of the present study was to evaluate the biological activity of a vascular endothelial cell-hydroxyapatite orbital complex, which was constructed with tissue engineering and used as an implant after enucleation of the eyeNew Zealand white rabbits were randomly divided into two groups that underwent hydroxyapatite orbital implant surgery in the right eye. The primary orbital microvascular endothelial cells were collected from the microvascular tissue and subsequently cultured. Then, hydroxyapatite ocular implants were cultured with vascular endothelial cells in the endothelial cell (EC) group, and implants were cultured without vascular endothelial cells in the blank group. Characterization of the cells was performed with immunofluorescence staining and a Transwell migration and cell tube formation assay. The levels of interleukin-8 (IL-8) and vascular endothelial growth factor (VEGF) in the rabbit conjunctiva were measured with an ELISA. The results showed that the levels of IL-8 were decreased in the EC group and increased in the blank group. The levels of VEGF were increased in the EC group when compared to the blank group with statistical significance. The average depth of the fibrovascular tissue was obviously thicker in the EC group compared with that found in the blank group. These findings suggest that the vascular endothelial cell-hydroxyapatite orbital implant complex may be an effective strategy with which to accelerate vascularization and reduce complications of infection with satisfactory biological activity.

The Evolution of Orbital Implants and Current Breakthroughs in Material Design, Selection, Characterization, and Clinical Use

It is occasionally essential to surgically remove the damaged eye of the patient in the case of serious oculoorbital injuries, intraocular cancers, and other life-threatening diseases. An orbital implant is placed into the anophthalmic socket after the eye is removed to provide adequate volume reinstatement and revamp the cosmetic look of a normal eye. In the previous few decades, implant design and material selection criteria have progressed from basic nonporous polymeric spheres to devices with more complicated shapes and functions to ensure improved long-term clinical results. Because of their highly interconnected porous design, ceramic and polymeric porous implants have found popularity as a passive framework for fibrovascular ingrowth, with lower obstacle rates and the option of setting to improve prosthetic eye mobility. These materials, however, are not without flaws. The danger of migration and extrusion, infections after surgery, and poor motility transferred to the cosmetic ocular prosthesis are important elements of orbital implants of today. As a result, the development of novel biomaterials with improved functionalities (i.e., antibacterial effect, angiogenesis, and in situ moldability) that allow better eye replacement is more desirable than ever, highlighting one of the most challenging aspects of research topics in the field of ocular implants. This study highlights the history of orbital implants. It gives an outline of current advancements in the area, over and above some essential observations for materials design, selection, characterization, and transformation to clinical applications.

Preparation of multigradient hydroxyapatite scaffolds and evaluation of their osteoinduction properties

Porous hydroxyapatite (HA) scaffolds are often used as bone repair materials, owing to their good biocompatibility, osteoconductivity and low cost. Vascularization and osteoinductivity of porous HA scaffolds were limited in clinical application, and these disadvantages were need to be improved urgently. We used water-in-oil gelation and pore former methods to prepare HA spheres and a porous cylindrical HA container, respectively. The prepared HA spheres were filled in container to assemble into composite scaffold. By adjusting the solid content of the slurry (solid mixture of chitin sol and HA powder) and the sintering temperature, the porosity and crystallinity of the HA spheres could be significantly improved; and mineralization of the HA spheres significantly improved the biological activity of the composite scaffold. The multigradient (porosity, crystallinity and mineralization) scaffold (HA-700) filled with the mineralized HA spheres exhibited a lower compressive strength; however, in vivo results showed that their vascularization ability were higher than those of other groups, and their osteogenic Gini index (Go: an index of bone mass, and inversely proportional to bone mass) showed a continuous decrease with the implantation time. This study provides a new method to improve porous HA scaffolds and meet the demands of bone tissue engineering applications.

Simultaneous characterization of physical, chemical, and thermal properties of polymeric multilayers using infrared spectroscopic ellipsometry

In this study, multilayered films of polyethylenimine/poly (sodium-p-styrene sulfonate) (PEI)/(PSS) and type I collagen/heparin sodium (COL)/(HEP) were fabricated using the layer-by-layer technique, and fully characterized using Infrared Variable Angle Spectroscopic Ellipsometry (IRVASE) to simultaneously analyze the chemistry, thickness, and roughness of the multilayers with respect to changes in pH of the washing solution, and changes in temperature. Film topography and Young's modulus were obtained by atomic force microscopy (AFM) and nanoindentation. Our results show that with IRVASE it is possible to analyze the thickness of the multilayers prepared using a washing solution of pH 5, obtaining values of 71.7 nm and 40.3 nm for three bilayers of PEI/PSS and COL/HEP, respectively. Film roughness varies between multilayer systems, obtaining values of 37.76 nm for three bilayers of PEI/PSS and 33.58 nm for three bilayers of COL/HEP. Increasing the pH of the washing solution for PEI/PSS yielded thinner films that were less susceptible to thermal induced changes in film chemistry in the range of 25 - 150 °C. PEI/PSS films decreased in thickness with increasing temperature up to 75 °C, whereas above 75 °C film thickness increased. Through IRVASE, a transition temperature for the PEI/PSS multilayers was observed at 75 °C. Temperatures above 37 °C drastically alter the chemistry and the thickness of the COL/HEP multilayers indicating a possible degradation of the polymers. We obtained, through nanoindentation, a Young's modulus of 15000 kPa and 9000 kPa for 12 bilayers of PEI/PSS and COL/HEP, respectively. These results demonstrate that, using IRVASE, we can simultaneously evaluate the physical, chemical, and thermal properties of synthetic and natural multilayered polymeric films.

Orbital implants: State-of-the-art review with emphasis on biomaterials and recent advances

In the treatment of severe oculo-orbital traumas, intraocular malignancies or other life-threatening conditions it is sometimes necessary to surgically remove the patient's diseased eye. Following the removal of the eye, an orbital implant is inserted into the anophthalmic socket in order to provide satisfactory volume replacement and restore the aesthetic appearance of a normal eye. Over the last decades, the implant design and the criteria of materials selection evolved from simple non-porous polymeric sphere to devices with more complex shape and functionalities for ensuring better clinical outcomes in the long-term. Polymeric and ceramic porous implants have gained prominence since their highly interconnected porous architecture allows them to act as a passive framework for fibrovascular in-growth offering reduced complication rates and the possibility of pegging to enhance the motility of the artificial eye. However, there are still drawbacks to these materials. Some critical aspects of today's orbital implants include the risk of migration and extrusion, postoperative infections and low motility transmitted to the aesthetic ocular prosthesis. Hence, the development of novel biomaterials with enhanced functionalities (e.g. angiogenesis, antibacterial effect, in situ mouldability) which enable an improved outcome of eye replacement is more than ever desirable and represents one of the most challenging topics of research in the field of ocular implants. This review summarizes the evolution of orbital implants and provides an overview of the most recent advances in the field as well as some critical remarks for materials design, selection, characterization and translation to clinical applications.

REDV–polyethyleneimine complexes for selectively enhancing gene delivery in endothelial cells

Gene therapy provides a new strategy for promoting endothelialization, and rapid endothelialization has attracted increasing attention for inhibiting thrombosis and restenosis in artificial vascular implants.