Innovative Human Three-Dimensional Tissue-Engineered Models as an Alternative to Animal Testing

Animal testing has long been used in science to study complex biological phenomena that cannot be investigated using two-dimensional cell cultures in plastic dishes. With time, it appeared that more differences could exist between animal models and even more when translated to human patients. Innovative models became essential to develop more accurate knowledge. Tissue engineering provides some of those models, but it mostly relies on the use of prefabricated scaffolds on which cells are seeded. The self-assembly protocol has recently produced organ-specific human-derived three-dimensional models without the need for exogenous material. This strategy will help to achieve the 3R principles.

Norbornene-Functionalized Chitosan Hydrogels and Microgels via Unprecedented Photoinitiated Self-Assembly for Potential Biomedical Applications

Access to biocompatible self-assembled gels and microgels is of great interests for a variety of biological applications from tissue engineering to drug delivery. Here, the facile synthesis of supramolecular hydrogels of norbornene (nb)-functionalized chitosan (CS-nb) via UV-triggered self-assembly in the presence of Irgacure 2959 (IRG) is reported. The in vitro stable hydrogels are injectable and showed pH-responsive swelling behavior, while their structure and mechanical properties could be tuned by tailoring the stereochemistry of the norbornene derivative (e.g., endo- or -exo). Interestingly, unlike other nb-type hydrogels, the gels possess nanopores within their structure, which might lead to potential drug delivery applications. A gelation mechanism was proposed based on hydrophobic interactions following the combination of IRG on norbornene, as supported by ¹H NMR. This self-assembly mechanism was used to access microgels of size 100-150 nm, which could be further functionalized and showed no significant toxicity to human dermofibroblast cells.

Hidrogeles de colágeno acoplados con hidroxiapatita para aplicaciones en ingeniería tisular

Los hidrogeles basados en colágeno son redes tridimensionales (3D) con la capacidad de absorber agua y una alta biocompatibilidad para utilizarlos en la reparación de tejidos dañados. Estos materiales presentan pobres propiedades mecánicas y velocidades de degradación rápidas, limitando su aplicación a estrategias de ingeniería tisular y biomedicina; por ésto, la incorporación de fases inorgánicas en la matriz 3D del colágeno como la hidroxiapatita ha contribuido en la mejora de sus propiedades, incrementado la eficiencia de los hidrogeles híbridos obtenidos. Este trabajo, presenta las contribuciones más relevantes relacionadas con los sistemas de hidrogeles basados en colágeno y partículas de hidroxiapatita dispersas dentro de la matriz colagénica, lo que evidencia que la combinación de los materiales no altera la biocompatibilidad y biodegradabilidad típicas del colágeno, permitiendo la adhesión, proliferación, crecimiento celular y control del metabolismo de las células implicadas en los procesos de una reparación ósea, presentando a los hidrogeles como una estrategia para su uso potencial en la ingeniería tisular.

Natural Polymeric Scaffolds in Bone Regeneration

Despite considerable advances in microsurgical techniques over the past decades, bone tissue remains a challenging arena to obtain a satisfying functional and structural restoration after damage. Through the production of substituting materials mimicking the physical and biological properties of the healthy tissue, tissue engineering strategies address an urgent clinical need for therapeutic alternatives to bone autografts. By virtue of their structural versatility, polymers have a predominant role in generating the biodegradable matrices that hold the cells in situ to sustain the growth of new tissue until integration into the transplantation area (i.e., scaffolds). As compared to synthetic ones, polymers of natural origin generally present superior biocompatibility and bioactivity. Their assembly and further engineering give rise to a wide plethora of advanced supporting materials, accounting for systems based on hydrogels or scaffolds with either fibrous or porous architecture. The present review offers an overview of the various types of natural polymers currently adopted in bone tissue engineering, describing their manufacturing techniques and procedures of functionalization with active biomolecules, and listing the advantages and disadvantages in their respective use in order to critically compare their actual applicability potential. Their combination to other classes of materials (such as micro and nanomaterials) and other innovative strategies to reproduce physiological bone microenvironments in a more faithful way are also illustrated. The regeneration outcomes achieved in vitro and in vivo when the scaffolds are enriched with different cell types, as well as the preliminary clinical applications are presented, before the prospects in this research field are finally discussed. The collection of studies herein considered confirms that advances in natural polymer research will be determinant in designing translatable materials for efficient tissue regeneration with forthcoming impact expected in the treatment of bone defects.

Flexible, dense and porous chitosan and alginate membranes containing the standardized extract of Arrabidaea chica Verlot for the treatment of skin lesions

The combination of chitosan (C) with alginate (A) has been explored for the production of dressings due to the positive results on wound healing. CA films can show a dense or porous flexible structure, with characteristics tunable for different applications. Porosity and flexibility can be achieved, respectively, by the addition of surfactants such as Kolliphor® P188 (P) and silicone-based compounds as Silpuran® 2130 A/B (S). Furthermore, composite matrices of these polysaccharides have potential applications as devices for releasing bioactive compounds to skin lesions. The purpose of this study was to evaluate the physicochemical and biological characteristics of flexible dense and porous CA membranes incorporating the standardized extract of Arrabidaea chica Verlot (A. chica), and also to analyze the release mechanism of the extract from different membrane formulations. The results show that the inclusion of P in the formulation allows obtaining porous matrices, promotes greater homogeneity of the mixture of the silicone gel with the suspension of polysaccharides, and increases the swelling of the polymer matrix. All formulations presented high stability, reaching a maximum mass loss of 18% after seven days. The formulations with S showed the best performance in terms of flexibility and strain at break. The presence of A. chica standardized extract did not affect negatively the characteristics of the membranes. Incorporation efficiencies of the bioactive compound above 87% were achieved, and the addition of P and S to the membrane formulation changed the release of the A. chica extract kinetics. In addition, the developed formulations did not significantly affect Vero cells proliferation.

Preparation of complex microcapsules of soluble polysaccharide from Glycyrrhiza uralensis and its application in wound repair and scar inhibition

The extraction process of Glycyrrhiza soluble polysaccharide (GP) was optimized by RSM, a rat trauma model was established via longitudinal incision on the back skin. The effects of GP combined with microcapsule collagen on the repair of rat injury model were discussed at different levels, Based on the content of hydroxyproline at the whole animal level, the proliferation of granulation tissue stained by HE, the number of microvessels labeled by CD34, the production of collagen fibers stained by Masson, the level of phosphorylation of STAT3 protein and that of VEGF at protein level were investigated. The results showed that after the administration of GP combined with microcapsules, the content of hydroxyproline in granulation tissue increased, the proliferation of capillaries and fibroblasts in granulation tissue became active, and the number of microvessels in wound increased. The formation density of collagen fibers was uniform and orderly. GP combined with microcapsules could activate the expression of p-STAT3 and VEGF proteins and up-regulate the transcription level of VEGF mRNA and miRNA-21 genes. Furthermore, GP combined with microcapsules could accelerate wound healing and promote neovascularization.

Synthesis and structure of carboxymethylcellulose with a high degree of substitution derived from waste disposable paper cups

The cost of the cellulose derived from some raw materials was high. In addition, the dispersion of the cellulose with special shape and a low degree of substitution (DS) in water-soluble polymers was poor. To resolve this problem, cellulose was separated from waste disposable paper cups (WDPC) and then the carboxymethylcellulose (CMC) was synthesized by etherification. Under the optimized conditions (the etherification temperature of 70 ℃, the etherification time of 1.5 h, the monochloroacetic acid mass (C₂H₃ClO₂) of 7 g), the DS of CMC was as high as 1.21. As-prepared CMC showed ribbon and rod-like shapes with a diameter of 25-50 μm. In addition, they exhibited an excellent thermal stability. Compared with other CMC, we could infer that as-prepared CMC in this paper will have potential applications in flexible composites and functional materials.

Advanced Biomaterials and Processing Methods for Liver Regeneration: State-of-the-Art and Future Trends

Liver diseases contribute markedly to the global burden of mortality and disease. The limited organ disposal for orthotopic liver transplantation results in a continuing need for alternative strategies. Over the past years, important progress has been made in the field of tissue engineering (TE). Many of the early trials to improve the development of an engineered tissue construct are based on seeding cells onto biomaterial scaffolds. Nowadays, several TE approaches have been developed and are applied to one vital organ: the liver. Essential elements must be considered in liver TE-cells and culturing systems, bioactive agents or growth factors (GF), and biomaterials and processing methods. The potential of hepatocytes, mesenchymal stem cells, and others as cell sources is demonstrated. They need engineered biomaterial-based scaffolds with perfect biocompatibility and bioactivity to support cell proliferation and hepatic differentiation as well as allowing extracellular matrix deposition and vascularization. Moreover, they require a microenvironment provided using conventional or advanced processing technologies in order to supply oxygen, nutrients, and GF. Herein the biomaterials and the conventional and advanced processing technologies, including cell-sheets process, 3D bioprinting, and microfluidic systems, as well as the future trends in these major fields are discussed.

In vitro characterization of a novel magnetic fibrin-agarose hydrogel for cartilage tissue engineering

The encapsulation of cells into biopolymer matrices enables the preparation of engineered substitute tissues. Here we report the generation of novel 3D magnetic biomaterials by encapsulation of magnetic nanoparticles and human hyaline chondrocytes within fibrin-agarose hydrogels, with potential use as articular hyaline cartilage-like tissues. By rheological measurements we observed that, (i) the incorporation of magnetic nanoparticles resulted in increased values of the storage and loss moduli for the different times of cell culture; and (ii) the incorporation of human hyaline chondrocytes into nonmagnetic and magnetic fibrin-agarose biomaterials produced a control of their swelling capacity in comparison with acellular nonmagnetic and magnetic fibrin-agarose biomaterials. Interestingly, the in vitro viability and proliferation results showed that the inclusion of magnetic nanoparticles did not affect the cytocompatibility of the biomaterials. What is more, immunohistochemistry showed that the inclusion of magnetic nanoparticles did not negatively affect the expression of type II collagen of the human hyaline chondrocytes. Summarizing, our results suggest that the generation of engineered hyaline cartilage-like tissues by using magnetic fibrin-agarose hydrogels is feasible. The resulting artificial tissues combine a stronger and stable mechanical response, with promising in vitro cytocompatibility. Further research would be required to elucidate if for longer culture times additional features typical of the extracellular matrix of cartilage could be expressed by human hyaline chondrocytes within magnetic fibrin-agarose hydrogels.

Marine Seaweed Polysaccharides-Based Engineered Cues for the Modern Biomedical Sector

Seaweed-derived polysaccharides with unique structural and functional entities have gained special research attention in the current medical sector. Seaweed polysaccharides have been or being used to engineer novel cues with biomedical values to tackle in practice the limitations of counterparts which have become ineffective for 21st-century settings. The inherited features of seaweed polysaccharides, such as those of a biologically tunable, biocompatible, biodegradable, renewable, and non-toxic nature, urge researchers to use them to design therapeutically effective, efficient, controlled delivery, patient-compliant, and age-compliant drug delivery platforms. Based on their significant retention capabilities, tunable active units, swelling, and colloidal features, seaweed polysaccharides have appeared as highly useful materials for modulating drug-delivery and tissue-engineering systems. This paper presents a standard methodological approach to review the literature using inclusion-exclusion criteria, which is mostly ignored in the reported literature. Following that, numerous marine-based seaweed polysaccharides are discussed with suitable examples. For the applied perspectives, part of the review is focused on the biomedical values, i.e., targeted drug delivery, wound-curative potential, anticancer potentialities, tissue-engineering aspects, and ultraviolet (UV) protectant potential of seaweed polysaccharides based engineered cues. Finally, current challenges, gaps, and future perspectives have been included in this review.

Adipose-Derived Stem Cells in Bone Tissue Engineering: Useful Tools with New Applications

Adipose stem cells (ASCs) are a crucial element in bone tissue engineering (BTE). They are easy to harvest and isolate, and they are available in significative quantities, thus offering a feasible and valid alternative to other sources of mesenchymal stem cells (MSCs), like bone marrow. Together with an advantageous proliferative and differentiative profile, they also offer a high paracrine activity through the secretion of several bioactive molecules (such as growth factors and miRNAs) via a sustained exosomal release which can exert efficient conditioning on the surrounding microenvironment. BTE relies on three key elements: (1) scaffold, (2) osteoprogenitor cells, and (3) bioactive factors. These elements have been thoroughly investigated over the years. The use of ASCs has offered significative new advancements in the efficacy of each of these elements. Notably, the phenotypic study of ASCs allowed discovering cell subpopulations, which have enhanced osteogenic and vasculogenic capacity. ASCs favored a better vascularization and integration of the scaffolds, while improvements in scaffolds' materials and design tried to exploit the osteogenic features of ASCs, thus reducing the need for external bioactive factors. At the same time, ASCs proved to be an incredible source of bioactive, proosteogenic factors that are released through their abundant exosome secretion. ASC exosomes can exert significant paracrine effects in the surroundings, even in the absence of the primary cells. These paracrine signals recruit progenitor cells from the host tissues and enhance regeneration. In this review, we will focus on the recent discoveries which have involved the use of ASCs in BTE. In particular, we are going to analyze the different ASCs' subpopulations, the interaction between ASCs and scaffolds, and the bioactive factors which are secreted by ASCs or can induce their osteogenic commitment. All these advancements are ultimately intended for a faster translational and clinical application of BTE.

Design of high conductive and piezoelectric poly (3,4-ethylenedioxythiophene)/chitosan nanofibers for enhancing cellular electrical stimulation

Electroactive nanofibrous scaffold is a vital tool for the study of the various biological research fields from bioelectronics to regenerative medicine, which can provide cell preferable 3D nanofiber architecture and programmed electrical signal. However, intrinsic non-biodegradability is a major problem that hinders its widespread application in the clinic. Herein, we designed, synthesized, and characterized shell/core poly (3,4-ethylenedioxythiophene) (PEDOT)/chitosan (CS) nanofibers by combining the electrospinning and recrystallization processes. Upon incorporating a trace amount of PEDOT (1.0 wt%), the resultant PEDOT/CS nanofibers exhibited low interfacial charge transfer impedance, high electrochemical stability, high electrical conductivity (up to 0.1945 S/cm), and ultrasensitive piezoelectric property (output voltage of 22.5 mV by a human hair prodding). With such unique electrical and conductive properties, PEDOT/CS nanofibers were further applied to brain neuroglioma cells (BNCs) to stimulate their adhesion, proliferation, growth, and development under an optimal external electrical stimulation (ES) and a pulse voltage of 400 mV/cm. ES-responsive PEDOT/CS nanofibers indeed promoted BNCs growth and development as indicated by a large number and density of axons. The synergetic interplay between external ES and piezoelectric voltage demonstrates new PEDOT-based nanofibers as implantable electroactive scaffolds for numerous applications in nerve tissue engineering, human health monitoring, brain mantle information extraction, and degradable microelectronic devices.

Modification of Starch via the Biginelli Multicomponent Reaction

An efficient and straightforward modification of starch using renewable and commercially available aromatic aldehydes (benzaldehyde, vanillin, and p-anisaldehyde) and urea via the Biginelli multicomponent reaction is reported in this work. First, starch acetoacetate (SAA) with a degree of substitution ranging from 1.4 to 2.5, depending on the reaction time or the molar ratio of reactants, is prepared. SAA is then modified with different aromatic aldehydes and urea via the Biginelli reaction. The modified products are characterized by ATR-IR, NMR, and gel permeation chromatography (GPC). The processability of the products is also investigated using a hot press instrument, revealing that glycerol is a suitable and renewable plasticizer for the Biginelli products.

Sources, Extraction and Biomedical Properties of Polysaccharides

In the recent era, bioactive compounds from plants have received great attention because of their vital health-related activities, such as antimicrobial activity, antioxidant activity, anticoagulant activity, anti-diabetic activity, UV protection, antiviral activity, hypoglycemia, etc. Previous studies have already shown that polysaccharides found in plants are not likely to be toxic. Based on these inspirational comments, most research focused on the isolation, identification, and bioactivities of polysaccharides. A large number of biologically active polysaccharides have been isolated with varying structural and biological activities. In this review, a comprehensive summary is provided of the recent developments in the physical and chemical properties as well as biological activities of polysaccharides from a number of important natural sources, such as wheat bran, orange peel, barely, fungi, algae, lichen, etc. This review also focused on biomedical applications of polysaccharides. The contents presented in this review will be useful as a reference for future research as well as for the extraction and application of these bioactive polysaccharides as a therapeutic agent.

Injectable Alginate-Peptide Composite Hydrogel as a Scaffold for Bone Tissue Regeneration

The high demand for tissue engineering scaffolds capable of inducing bone regeneration using minimally invasive techniques prompts the need for the development of new biomaterials. Herein, we investigate the ability of Alginate incorporated with the fluorenylmethoxycarbonyl-diphenylalanine (FmocFF) peptide composite hydrogel to serve as a potential biomaterial for bone regeneration. We demonstrate that the incorporation of the self-assembling peptide, FmocFF, in sodium alginate leads to the production of a rigid, yet injectable, hydrogel without the addition of cross-linking agents. Scanning electron microscopy reveals a nanofibrous structure which mimics the natural bone extracellular matrix. The formed composite hydrogel exhibits thixotropic behavior and a high storage modulus of approximately 10 kPA, as observed in rheological measurements. The in vitro biocompatibility tests carried out with MC3T3-E1 preosteoblast cells demonstrate good cell viability and adhesion to the hydrogel fibers. This composite scaffold can induce osteogenic differentiation and facilitate calcium mineralization, as shown by Alizarin red staining, alkaline phosphatase activity and RT-PCR analysis. The high biocompatibility, excellent mechanical properties and similarity to the native extracellular matrix suggest the utilization of this hydrogel as a temporary three-dimensional cellular microenvironment promoting bone regeneration.

Emerging Biomedical Applications of Algal Polysaccharides

BACKGROUND

Over the past two decades, there have been substantial progress and a growing body of research on using natural polymeric biomaterials in emerging biomedical applications. Among different natural biopolymers, polysaccharides have gained considerable attraction among biomedical scientists and surgeons due to their biocompatibility, biodegradability, anti-inflammatory, and antimicrobial properties. In recent years, algalbased polysaccharides including agar, alginate, and carrageenan, have been broadly suggested for different biomedical applications.

METHODS

The aim of this paper is discussing various possible applications of algal-based polysaccharides in biomedical engineering particularly in controlled drug delivery systems. The main properties of each algal polysaccharide will be discussed, and particular drug delivery applications will be presented.

RESULTS

Algal polysaccharides can be detected in a group of photosynthetic unite as their key biomass constituents. They provide a range of variety in their size, shape, liquefaction, chemical stability, and crosslinking ability. In addition, algal polysaccharides have shown exceptional gelling properties including stimuli-responsive behavior, softness, and swelling properties.

CONCLUSION

All the mentioned properties of alga polysaccharides lead to their successful usage in biomedical applications specially targeted and controlled drug delivery systems such as particles, capsules, and gels.

RHAMM induces progression of rheumatoid arthritis by enhancing the functions of fibroblast-like synoviocytes

Background

Rheumatoid arthritis (RA) is a chronic and refractory autoimmune joint disease. Fibroblast-like synoviocytes (FLS) produce inflammatory cytokines and are involved in the migration and invasion of panuus tissue, which leads to the destruction of joints in RA. Receptor for hyaluronan mediated motility (RHAMM), is known to be one of the important receptors for hyaluronic acid. It has the ability to regulate migration of fibrocytes and infiltration of inflammatory cells. Here,we explored the mechanisms of RHAMM in RAFs.

Methods

Quantitative PCR and western blot were performed to test the expression of RHAMM in synoviocytes of RA patients and osteoarthritis (OA) controls. Collagen antibody-induced arthritis (CAIA) was used to investigate the RHAMM expression in mouse synovial issues. RHAMM siRNA was used to detect the function of RHAMM in FLS.

Results

RA-FLS has a significantly higher expression of RHAMM than OA-FLS. Expression of RHAMM in joint synovial tissue was markedly increased in the CAIA mice compared with the controls. RHAMM silencing using SiRNA was not only decreased the production of IL-6 and IL-8, but also inhibited the migration and invasion of RA-FLS.

Conclusions

RHAMM has an important role in the FLS induced modulation of inflammation and destruction of joints in RA.

Proteomics analysis of chicken peripheral blood lymphocyte in Taishan Pinus massoniana pollen polysaccharide regulation

The natural polysaccharides extracted from the pollen of Pinus massoniana (TPPPS) have been shown to be a promising immune adjuvant against several viral chicken diseases. However, the exact mechanism through which TPPPS enhances the host immune response in chicken remains poorly understood. In the current study, chicken peripheral blood lymphocytes were treated with varying concentrations of TPPPS and pro-inflammatory cytokines such as IFN-γ, iIL-2 and IL-6 were measured to determine the optimal dose of the polysaccharide. A comparative analysis was subsequently performed between the proteome of lymphocytes subjected to the best treatment conditions and that of untreated cells. Protein identification and quantitation revealed a panel of three up-regulated and seven down-regulated candidates in TPPPS-treated chicken peripheral blood lymphocytes. Further annotation and functional analysis suggested that a number of those protein candidates were involved in the regulation of host innate immune response, inflammation and other immune-related pathways. We believe that our results could serve as a stepping stone for further research on the immune-enhancing properties of TPPPS and other polysaccharide-based immune adjuvants.

Borrowing From Nature: Biopolymers and Biocomposites as Smart Wound Care Materials

Wound repair is a complex and tightly regulated physiological process, involving the activation of various cell types throughout each subsequent step (homeostasis, inflammation, proliferation, and tissue remodeling). Any impairment within the correct sequence of the healing events could lead to chronic wounds, with potential effects on the patience quality of life, and consequent fallouts on the wound care management. Nature itself can be of inspiration for the development of fully biodegradable materials, presenting enhanced bioactive potentialities, and sustainability. Naturally-derived biopolymers are nowadays considered smart materials. They provide a versatile and tunable platform to design the appropriate extracellular matrix able to support tissue regeneration, while contrasting the onset of adverse events. In the past decades, fabrication of bioactive materials based on natural polymers, either of protein derivation or polysaccharide-based, has been extensively exploited to tackle wound-healing related problematics. However, in today's World the exclusive use of such materials is becoming an urgent challenge, to meet the demand of environmentally sustainable technologies to support our future needs, including applications in the fields of healthcare and wound management. In the following, we will briefly introduce the main physico-chemical and biological properties of some protein-based biopolymers and some naturally-derived polysaccharides. Moreover, we will present some of the recent technological processing and green fabrication approaches of novel composite materials based on these biopolymers, with particular attention on their applications in the skin tissue repair field. Lastly, we will highlight promising future perspectives for the development of a new generation of environmentally-friendly, naturally-derived, smart wound dressings.

Nanofibrous Scaffolds with Biomimetic Composition for Skin Regeneration

Treatments of skin injuries caused by trauma and diseases are among the most considerable medical problems. The use of scaffolds that can cover the wound area and support cellular ingrowth has shown great promise. However, mimicking the physicochemical properties of the native skin extracellular matrix (ECM) is essential for the successful integration of these scaffolds. Elastin has been known as the second main protein-based component of the native skin ECM. In this research, scaffolds containing gelatin, cellulose acetate, and elastin were fabricated using electrospinning. Subsequently, the effects of soluble elastin on the physical, mechanical, and biological properties of the prepared scaffolds were studied. The results confirmed that the presence of elastin in the composition changed the fiber morphology from straight to ribbon-like structure and decreased the swelling ratio and degradation rate of the scaffold. In vitro experiments showed that elastin-containing scaffolds supported the attachment and proliferation of fibroblast cells. Overall, the obtained results suggest the ternary blend of gelatin, cellulose acetate, and elastin as a good candidate for skin tissue engineering.

Structural and rheological properties of pectic polysaccharide extracted from Ulmus davidiana esterified by succinic acid

The present study was carried out to investigate the physicochemical and structural properties of pectic polysaccharide extracted from Ulmus davidiana (UDP) and to determine the physicochemical, structural, and rheological properties of esterified UDP with succinic acid (ES-UDP). The results indicated that UDP had high amounts of galacturonic acids and various neutral sugars, such as galactose, rhamnose, and glucose. UDP was identified as a low methoxyl pectin, consisting of 1,4-linked α-d-GalpA (the main backbone chain), supported by the results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction, and 1D Nuclear magnetic resonance (NMR) spectroscopy. In the FT-IR and XRD, no difference was detected between UPD and ES-UDPs. However, ¹H and ¹³C NMR spectra revealed that the new ester bonds were formed between a hydroxyl group of UDP and a carboxyl group of succinic acid during esterification. In the steady shear rheological analysis, the consistency index (K) of ES-UDP was significantly higher than that of UDP and increased significantly with increasing concentration of succinic acid. In the dynamic rheological analysis, the tan δ values of all ES-UDP solutions were significantly lower than those of the UDP solution.

Cellulose exopolysaccharide from sugarcane molasses as a suitable substrate for 2D and 3D neuron and astrocyte primary cultures

Bacteria-synthesized polysaccharides have attracted interest for biomedical applications as promising biomaterials to be used as implants and scaffolds. The present study tested the hypothesis that cellulose exopolysaccharide (CEC) produced from sugarcane molasses of low cost and adequate purity would be suitable as a template for 2D and 3D neuron and/or astrocyte primary cultures, considering its low toxicity. CEC biocompatibility in these primary cultures was evaluated with respect to cell viability, adhesion, growth and cell function (calcium imaging). Polystyrene or Matrigel® matrix were used as comparative controls. We demonstrated that the properties of this CEC in the 2D or 3D configurations are suitable for differentiation of cortical astrocytes and neurons in single or mixed cultures. No toxicity was detected in neurons that showed NMDA-induced Ca²⁺ influx. Unlike other polysaccharides of bacterial synthesis, the CEC was efficient as a support even in the absence of surface conjugation with extracellular matrix proteins, maintaining physiological characteristics of cultured neural cells. These observations open up the perspective for development of a novel 3D biofunctional scaffold produced from bacterial cellulose and obtained from renewable sources whose residues are not pollutants. Its low cost and possibility to be manufactured in scale are also suitable for potential applications in regenerative medicine.

Osteogenic Potential of Graphene in Bone Tissue Engineering Scaffolds

Scaffolds are physical substrates for cell attachments, proliferation, and differentiation, ultimately leading to tissue regeneration. Current literature validates tissue engineering as an emerging tool for bone regeneration. Three-dimensionally printed natural and synthetic biomaterials have been traditionally used for tissue engineering. In recent times, graphene and its derivatives are potentially employed for constructing bone tissue engineering scaffolds because of their osteogenic and regenerative properties. Graphene is a synthetic atomic layer of graphite with SP2 bonded carbon atoms that are arranged in a honeycomb lattice structure. Graphene can be combined with natural and synthetic biomaterials to enhance the osteogenic potential and mechanical strength of tissue engineering scaffolds. The objective of this review is to focus on the most recent studies that attempted to explore the salient features of graphene and its derivatives. Perhaps, a thorough understanding of the material science can potentiate researchers to use this novel substitute to enhance the osteogenic and biological properties of scaffold materials that are routinely used for bone tissue engineering.

A simple strategy for robust preparation and characterisation of hydrogels derived from chitosan and amino functional monomers for biomedical applications

Molecular interactions of amino functional (AF) monomers with chitosan (CS) lead to the formation of external stimuli responsive hydrogels (HGs). These have the potential to produce biomaterials with novel properties by a simple blending approach. Six independent AF monomers such as diethylenetriamine (DETA), bis(3-aminopropyl)amine (BAPA), 3,3'-diamino-N-methyldipropyleamine (DAMPA), hexamethylenediamine (HMDA), N,N-dimethylethylamine (DMEA) and diethylamine (DEA) with distinct functional groups and chain lengths were designed to form stable HGs at physiological pH. Such AF monomers are able to form HGs within a short time (in the range from 10 to 19 seconds) by physically interacting with CS. This is an alternative to the covalently crosslinking reaction process, providing cost effective HG biomaterials. HG complexes were characterized by rheometry, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The interaction between AF monomers and the CS polymer has been discussed and the results have been confirmed by FTIR analysis. The storage modulus (G'), loss modulus (G'') and complex viscosity (η*) were evaluated for all HGs using a rheometer, and the ratios of CS and the particular AF monomer were optimized for stable HG formation. The swelling ratio was evaluated using a simple method and was found to be directly related to the structure of the AF monomer, pH and temperature. These HGs were utilised for encapsulation, and the release of active molecules (e.g., reactive red 120 (RR120) as a model compound) was measured at low pH 5.5, physiological pH 7.4 and high pH 9.5. The cell viability and cellular compatibility of the HGs were evaluated in vitro cell culture, demonstrating that all the five different types of HGs support cellular compatibility, attachment and growth. The physical mixing of AF monomers with CS is expedited for the development of new bespoke economically viable biomaterials.

Autologous liquid platelet rich fibrin: A novel drug delivery system

There is currently widespread interest within the biomaterial field to locally deliver biomolecules for bone and cartilage regeneration. Substantial work to date has focused on the potential role of these biomolecules during the healing process, and the carrier system utilized is a key factor in their effectiveness. Platelet rich fibrin (PRF) is a naturally derived fibrin scaffold that is easily obtained from peripheral blood following centrifugation. Slower centrifugation speeds have led to the commercialization of a liquid formulation (liquid-PRF) resulting in an upper plasma layer composed of liquid fibrinogen/thrombin prior to clot formation that remains in its liquid phase for approximately 15 min until injected into bodily tissues. Herein, we introduce the use of liquid PRF as an advanced local delivery system for small and large biomolecules. Potential target molecules including large (growth factors/cytokines and morphogenetic/angiogenic factors), as well as small (antibiotics, peptides, gene therapy and anti-osteoporotic) molecules are considered potential candidates for enhanced bone/cartilage tissue regeneration. Furthermore, liquid-PRF is introduced as a potential carrier system for various cell types and nano-sized particles that are capable of limiting/by-passing the immune system and minimizing potential foreign body reactions within host tissues following injection.

STATEMENT OF SIGNIFICANCE

There is currently widespread interest within the biomaterial field to locally deliver biomolecules for bone and cartilage regeneration. This review article focuses on the use of a liquid version of platelet rich fibrin (PRF) composed of liquid fibrinogen/thrombin as a drug delivery system. Herein, we introduce the use of liquid PRF as an advanced local delivery system for small and large biomolecules including growth factors, cytokines and morphogenetic/angiogenic factors, as well as antibiotics, peptides, gene therapy and anti-osteoporotic molecules as potential candidates for enhanced bone/cartilage tissue regeneration.

Decellularized matrices in regenerative medicine

Of all biologic matrices, decellularized extracellular matrix (dECM) has emerged as a promising tool used either alone or when combined with other biologics in the fields of tissue engineering or regenerative medicine - both preclinically and clinically. dECM provides a native cellular environment that combines its unique composition and architecture. It can be widely obtained from native organs of different species after being decellularized and is entitled to provide necessary cues to cells homing. In this review, the superiority of the macro- and micro-architecture of dECM is described as are methods by which these unique characteristics are being harnessed to aid in the repair and regeneration of organs and tissues. Finally, an overview of the state of research regarding the clinical use of different matrices and the common challenges faced in using dECM are provided, with possible solutions to help translate naturally derived dECM matrices into more robust clinical use.

STATEMENT OF SIGNIFICANCE

Ideal scaffolds mimic nature and provide an environment recognized by cells as proper. Biologically derived matrices can provide biological cues, such as sites for cell adhesion, in addition to the mechanical support provided by synthetic matrices. Decellularized extracellular matrix is the closest scaffold to nature, combining unique micro- and macro-architectural characteristics with an equally unique complex composition. The decellularization process preserves structural integrity, ensuring an intact vasculature. As this multifunctional structure can also induce cell differentiation and maturation, it could become the gold standard for scaffolds.

Exploiting natural polysaccharides to enhance in vitro bio-constructs of primary neurons and progenitor cells

Current strategies in Central Nervous System (CNS) repair focus on the engineering of artificial scaffolds for guiding and promoting neuronal tissue regrowth. Ideally, one should combine such synthetic structures with stem cell therapies, encapsulating progenitor cells and instructing their differentiation and growth. We used developments in the design, synthesis, and characterization of polysaccharide-based bioactive polymeric materials for testing the ideal composite supporting neuronal network growth, synapse formation and stem cell differentiation into neurons and motor neurons. Moreover, we investigated the feasibility of combining these approaches with engineered mesenchymal stem cells able to release neurotrophic factors. We show here that composite bio-constructs made of Chitlac, a Chitosan derivative, favor hippocampal neuronal growth, synapse formation and the differentiation of progenitors into the proper neuronal lineage, that can be improved by local and continuous delivery of neurotrophins.

STATEMENT OF SIGNIFICANCE

In our work, we characterized polysaccharide-based bioactive platforms as biocompatible materials for nerve tissue engineering. We show that Chitlac-thick substrates are able to promote neuronal growth, differentiation, maturation and formation of active synapses. These observations support this new material as a promising candidate for the development of complex bio-constructs promoting central nervous system regeneration. Our novel findings sustain the exploitation of polysaccharide-based scaffolds able to favour neuronal network reconstruction. Our study shows that Chitlac-thick may be an ideal candidate for the design of biomaterial scaffolds enriched with stem cell therapies as an innovative approach for central nervous system repair.

Tissue engineering with gellan gum

Engineering complex tissues for research and clinical applications relies on high-performance biomaterials that are amenable to biofabrication, maintain mechanical integrity, support specific cell behaviours, and, ultimately, biodegrade. In most cases, complex tissues will need to be fabricated from not one, but many biomaterials, which collectively fulfill these demanding requirements. Gellan gum is an anionic polysaccharide with potential to fill several key roles in engineered tissues, particularly after modification and blending. This review focuses on the present state of research into gellan gum, from its origins, purification and modification, through processing and biofabrication options, to its performance as a cell scaffold for both soft tissue and load bearing applications. Overall, we find gellan gum to be a highly versatile backbone material for tissue engineering research, upon which a broad array of form and functionality can be built.

Tissue Engineered Skin Substitutes

The fundamental skin role is to supply a supportive barrier to protect body against harmful agents and injuries. Three layers of skin including epidermis, dermis and hypodermis form a sophisticated tissue composed of extracellular matrix (ECM) mainly made of collagens and glycosaminoglycans (GAGs) as a scaffold, different cell types such as keratinocytes, fibroblasts and functional cells embedded in the ECM. When the skin is injured, depends on its severity, the majority of mentioned components are recruited to wound regeneration. Additionally, different growth factors like fibroblast growth factor (FGF), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) are needed to orchestrated wound healing process. In case of large surface area wounds, natural wound repair seems inefficient. Inspired by nature, scientists in tissue engineering field attempt to engineered constructs mimicking natural healing process to promote skin restoration in untreatable injuries. There are three main types of commercially available engineered skin substitutes including epidermal, dermal, and dermoepidermal. Each of them could be composed of scaffold, desired cell types or growth factors. These substitutes could have autologous, allogeneic, or xenogeneic origin. Moreover, they may be cellular or acellular. They are used to accelerate wound healing and recover normal skin functions with pain relief. Although there are a wide variety of commercially available skin substitutes, almost none of them considered as an ideal equivalents required for proper wound healing.

Designing Smart Biomaterials for Tissue Engineering

The engineering of human tissues to cure diseases is an interdisciplinary and a very attractive field of research both in academia and the biotechnology industrial sector. Three-dimensional (3D) biomaterial scaffolds can play a critical role in the development of new tissue morphogenesis via interacting with human cells. Although simple polymeric biomaterials can provide mechanical and physical properties required for tissue development, insufficient biomimetic property and lack of interactions with human progenitor cells remain problematic for the promotion of functional tissue formation. Therefore, the developments of advanced functional biomaterials that respond to stimulus could be the next choice to generate smart 3D biomimetic scaffolds, actively interacting with human stem cells and progenitors along with structural integrity to form functional tissue within a short period. To date, smart biomaterials are designed to interact with biological systems for a wide range of biomedical applications, from the delivery of bioactive molecules and cell adhesion mediators to cellular functioning for the engineering of functional tissues to treat diseases.