Development of a resorbable macroporous cellulosic material used as hemostatic in an osseous environment

Bacterial cellulose as a potential biopolymer in biomedical applications: a state-of-the-art review

Throughout history, natural biomaterials have benefited society. Nevertheless, in recent years, tailoring natural materials for diverse biomedical applications accompanied with sustainability has become the focus. With the progress in the field of materials science, novel approaches for the production, processing, and functionalization of biomaterials to obtain specific architectures have become achievable. This review highlights an immensely adaptable natural biomaterial, bacterial cellulose (BC). BC is an emerging sustainable biopolymer with immense potential in the biomedical field due to its unique physical properties such as flexibility, high porosity, good water holding capacity, and small size; chemical properties such as high crystallinity, foldability, high purity, high polymerization degree, and easy modification; and biological characteristics such as biodegradability, biocompatibility, excellent biological affinity, and non-biotoxicity. The structure of BC consists of glucose monomer units polymerized via cellulose synthase in β-1-4 glucan chains, creating BC nano fibrillar bundles with a uniaxial orientation. BC-based composites have been extensively investigated for diverse biomedical applications due to their similarity to the extracellular matrix structure. The recent progress in nanotechnology allows the further modification of BC, producing novel BC-based biomaterials for various applications. In this review, we strengthen the existing knowledge on the production of BC and BC composites and their unique properties, and highlight the most recent advances, focusing mainly on the delivery of active pharmaceutical compounds, tissue engineering, and wound healing. Further, we endeavor to present the challenges and prospects for BC-associated composites for their application in the biomedical field.

Controlling the degradation of cellulose scaffolds with Malaprade oxidation for tissue engineering

Cellulose scaffolds, whose biodegradation can be controlled through the reaction with amine compounds in the human body, were developed for tissue engineering applications.

Latest Advances on Bacterial Cellulose-Based Materials for Wound Healing, Delivery Systems, and Tissue Engineering

Bacterial cellulose (BC) is a nanocellulose form produced by some nonpathogenic bacteria. BC presents unique physical, chemical, and biological properties that make it a very versatile material and has found application in several fields, namely in food industry, cosmetics, and biomedicine. This review overviews the latest state-of-the-art usage of BC on three important areas of the biomedical field, namely delivery systems, wound dressing and healing materials, and tissue engineering for regenerative medicine. BC will be reviewed as a promising biopolymer for the design and development of innovative materials for the mentioned applications. Overall, BC is shown to be an effective and versatile carrier for delivery systems, a safe and multicustomizable patch or graft for wound dressing and healing applications, and a material that can be further tuned to better adjust for each tissue engineering application, by using different methods.

Biomaterials and Advanced Technologies for Hemostatic Management of Bleeding

Bleeding complications arising from trauma, surgery, and as congenital, disease-associated, or drug-induced blood disorders can cause significant morbidities and mortalities in civilian and military populations. Therefore, stoppage of bleeding (hemostasis) is of paramount clinical significance in prophylactic, surgical, and emergency scenarios. For externally accessible injuries, a variety of natural and synthetic biomaterials have undergone robust research, leading to hemostatic technologies including glues, bandages, tamponades, tourniquets, dressings, and procoagulant powders. In contrast, treatment of internal noncompressible hemorrhage still heavily depends on transfusion of whole blood or blood's hemostatic components (platelets, fibrinogen, and coagulation factors). Transfusion of platelets poses significant challenges of limited availability, high cost, contamination risks, short shelf-life, low portability, performance variability, and immunological side effects, while use of fibrinogen or coagulation factors provides only partial mechanisms for hemostasis. With such considerations, significant interdisciplinary research endeavors have been focused on developing materials and technologies that can be manufactured conveniently, sterilized to minimize contamination and enhance shelf-life, and administered intravenously to mimic, leverage, and amplify physiological hemostatic mechanisms. Here, a comprehensive review regarding the various topical, intracavitary, and intravenous hemostatic technologies in terms of materials, mechanisms, and state-of-art is provided, and challenges and opportunities to help advancement of the field are discussed.

Advances in biomedical and pharmaceutical applications of functional bacterial cellulose-based nanocomposites

Bacterial cellulose (BC) synthesized by certain species of bacteria, is a fascinating biopolymer with unique physical and mechanical properties. BC's applications range from traditional dessert, gelling, stabilizing and thickening agent in the food industry to advanced high-tech applications, such as immobilization of enzymes, bacteria and fungi, tissue engineering, heart valve prosthesis, artificial blood vessels, bone, cartilage, cornea and skin, and dental root treatment. Various BC-composites have been designed and investigated in order to enhance its biological applicability. This review focuses on the application of BC-based composites for microbial control, wound dressing, cardiovascular, ophthalmic, skeletal, and endodontics systems. Moreover, applications in controlled drug delivery, biosensors/bioanalysis, immobilization of enzymes and cells, stem cell therapy and skin tissue repair are also highlighted. This review will provide new insights for academia and industry to further assess the BC-based composites in terms of practical applications and future commercialization for biomedical and pharmaceutical purposes.

Epichlorohydrin-Cross-linked Hydroxyethyl Cellulose/Soy Protein Isolate Composite Films as Biocompatible and Biodegradable Implants for Tissue Engineering

A series of epichlorohydrin-cross-linked hydroxyethyl cellulose/soy protein isolate composite films (EHSF) was fabricated from hydroxyethyl cellulose (HEC) and soy protein isolate (SPI) using a process involving blending, cross-linking, solution casting, and evaporation. The films were characterized with FTIR, solid-state (13)C NMR, UV-vis spectroscopy, and mechanical testing. The results indicated that cross-linking interactions occurred in the inter- and intramolecules of HEC and SPI during the fabrication process. The EHSF films exhibited homogeneous structure and relative high light transmittance, indicating there was a certain degree of miscibility between HEC and SPI. The EHSF films exhibited a relative high mechanical strength in humid state and an adjustable water uptake ratio and moisture absorption ratio. Cytocompatibility, hemocompatibility and biodegradability were evaluated by a series of in vitro and in vivo experiments. These results showed that the EHSF films had good biocompatibility, hemocompatibility, and anticoagulant effect. Furthermore, EHSF films could be degraded in vitro and in vivo, and the degradation rate could be controlled by adjusting the SPI content. Hence, EHSF films might have a great potential for use in the biomedical field.

Role of polymeric biomaterials as wound healing agents

In uncontrolled hemorrhage, the main cause of death on the battlefield and in accidents, half of the deaths are caused by severe blood loss. Polymeric biomaterials have great potential in the control of severe hemorrhage from trauma, which is the second leading cause of death in the civilian community following central nervous system injuries. The intent of this article is to provide a review on currently available biopolymers used as wound dressing agents and to describe their best use as it relates to the condition and type of the wound (acute, chronic, superficial, and full thickness) and the phases of the wound healing process. These biopolymers are beneficial in tissue engineering as scaffolds, hydrogels, and films. Different types of wound dressings based on biopolymers are available in the market, with various physical, chemical, and biological properties. The use of biopolymers as a hemostatic agent depends on its biocompatibility, biodegradability, nonimmunogenicity, and optimal mechanical property. This review summarizes different biopolymers, their physiological characters, and their use as wound healing agents along with biomedical applications.

Bacterial cellulose-based materials and medical devices: current state and perspectives

Bacterial cellulose (BC) is a unique and promising material for use as implants and scaffolds in tissue engineering. It is composed of a pure cellulose nanofiber mesh spun by bacteria. It is remarkable for its strength and its ability to be engineered structurally and chemically at nano-, micro-, and macroscales. Its high water content and purity make the material biocompatible for multiple medical applications. Its biocompatibility, mechanical strength, chemical and morphologic controllability make it a natural choice for use in the body in biomedical devices with broader application than has yet been utilized. This paper reviews the current state of understanding of bacterial cellulose, known methods for controlling its physical and chemical structure (e.g., porosity, fiber alignment, etc.), biomedical applications for which it is currently being used, or investigated for use, challenges yet to be overcome, and future possibilities for BC.

Biomimetic calcium phosphate crystal mineralization on electrospun cellulose-based scaffolds

Novel cellulose based-scaffolds were studied for their ability to nucleate bioactive calcium phosphate crystals for future bone healing applications. Cellulose-based scaffolds were produced by electrospinning cellulose acetate (CA) dissolved in a mixture of acetone/dimethylacetamide (DMAc). The resulting nonwoven CA mats containing fibrils with diameters in the range of 200 nm to 1.5 μm were saponified by NaOH/ethanol for varying times to produce regenerated cellulose scaffolds. Biomimetic crystal growth nucleated from the fiber surface was studied as a function of surface chemistry. Regenerated cellulose scaffolds of varying treatments were soaked in simulated body fluid (SBF) solution. Scaffolds that were treated with CaCl(2), a mixture of carboxymethyl cellulose (CMC) and CaCl(2), and NaOH and CaCl(2), were analyzed using X-ray photoelectron spectroscopy, X-ray powder diffraction, and scanning electron microscopy to understand the growth of bioactive calcium phosphate (Ca-P) crystals as a function of surface treatment. The crystal structure of the nucleated Ca-P crystals had a diffraction pattern similar to that of hydroxyapatite, the mineralized component of bone. The study shows that the scaffold surface chemistry can be manipulated, providing numerous routes to engineer cellulosic substrates for the requirements of scaffolding.

Cyclo-DfKRG peptide modulates in vitro and in vivo behavior of human osteoprogenitor cells on titanium alloys

The first aim of the present study was to investigate the capacity of a cyclo-DfKRG-coated hydroxyapatite-titanium alloy (Ti-HA-RGD) to activate in vitro human osteoprogenitor cells adhesion and differentiation. The second purpose was to examine in vivo the role of a autologous cell seeding on cyclo-DfKRG-functionalized materials to provide bone repair after implantation in femoral condyle of rabbits. Our in vitro results have demonstrated that both titanium alloy functionalized with hydroxyapatite (Ti-HA-RGD and Ti-HA) contributed to higher cell adhesion than titanium alloy alone respectively 85 and 55% vs 15% compared to tissue culture polystyrene after one hour of cell seeding. As for differentiation, after 3 days of culture, Ti-HA presented the highest increase of ALP mRNA of all surfaces studied. Ti-HA-RGD showed an intermediate value about half as high as Ti-HA. Moreover after 3 days, both Ti-HA and Ti-HA-RGD surfaces showed the highest increase of cbfa1 mRNA expression. Two weeks following implantation, in vivo findings revealed that percentage of lacunae contact observed with pre-cellularized Ti-HA-RGD samples remains significantly lower than with Ti-HA group (10.5+/-9.6 % vs 33.7+/-11.5 %, P<0.03). Meanwhile, RGD peptide coating had no significant additional effect on the bone implant contact and area. Moreover, histomorphometry analysis revealed that implantation of pre-cellularized RGD coated materials with ROP cells increased significantly peri-implant fibrous area (24+/-11.6% vs 3+/-1.7% for Ti-HA-RGD, P<0.02). RGD coatings demonstrated osteoblastic adhesion, differentiation and in vivo bone regeneration at most equivalent to HA coatings.

In VitroandIn VivoDegradation of Oxidized Acetyl- and Ethyl-Cellulose Sponges

The objective of this study was to assess the in vitro and in vivo degradation properties of macroporous sponges composed of oxidized acetyl-cellulose (AC; 45.000 Mw) and ethyl-cellulose (EC; 50.000 Mw). The sponges were constructed by solvent-casting and particulate-leaching technique using a polymer concentration of 2.5 and 5.0% (w:v), and periodate oxidation. The resulting sponges were: AC2.5, AC5.0, EC2.5 and EC5.0. While AC sponges exhibited a gradual degradation overtime, EC sponges had a very slow in vitro mass loss. In general, sponges made up of 2.5% (w:v) polymer content degraded faster than the ones with 5.0% (w:v). The sponges degraded faster at pH 5.0, compared to pH 6.0 and 7.4 conditions. About 60%, 44% and 31% of dry mass loss was determined for AC2.5 sponges after 60 weeks at pH 5.0, pH 6.0 and pH 7.4 conditions, respectively; thus, ca. 21%, 13% and 12% of dry mass loss from EC2.5 sponges was observed at the same pH conditions, in the same order. The in vivo degradation studies were performed on Wistar rats (n = 24) for a duration of 60 weeks. In general, all sponge implants were well-tolerated by the subjects. While granulation tissue or fibrotic capsule was not formed around the sponges, neovascularization was observed. AC and EC sponges demonstrated an in vivo degradation behavior quite similar to that observed for the in vitro study conducted at pH 5.0 conditions. Histomorphometric analysis revealed that the in vivo degradation of AC2.5 and EC2.5 after 60 weeks was about 47% and 18%, respectively. The results indicate that oxidized acetyl cellulose may be considered as a partially degradable scaffold material for tissue engineering applications.