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

Electrospun Polymeric Nanofibers: Current Trends in Synthesis, Surface Modification, and Biomedical Applications

Electrospun polymeric nanofibers are essential in various fields for various applications because of their unique properties. Their features are similar to extracellular matrices, which suggests them for applications in healthcare fields, such as antimicrobials, tissue engineering, drug delivery, wound healing, bone regeneration, and biosensors. This review focuses on the synthesis of electrospun polymeric nanofibers, their surface modification, and their biomedical applications. Nanofibers can be fabricated from both natural and synthetic polymers and their composites. Even though they mimic extracellular matrices, their surface features (physicochemical characteristics) are not always capable of fulfilling the purpose of the target application. Therefore, they need to be improved via surface modification techniques. Both needle-based and needleless electrospinning are thoroughly discussed. Various techniques and setups employed in each method are also reviewed. Furthermore, pre- and postspinning modification approaches for electrospun nanofibers, including instrument design and the modification features for targeted biomedical applications, are also extensively discussed. In this way, the remarkable potential of electrospun polymeric nanofibers can be highlighted to reveal future research directions in this dynamic field.

Material matters: exploring the interplay between natural biomaterials and host immune system

Biomaterials are widely used for various medical purposes, for instance, implants, tissue engineering, medical devices, and drug delivery systems. Natural biomaterials can be obtained from proteins, carbohydrates, and cell-specific sources. However, when these biomaterials are introduced into the body, they trigger an immune response which may lead to rejection and failure of the implanted device or tissue. The immune system recognizes natural biomaterials as foreign substances and triggers the activation of several immune cells, for instance, macrophages, dendritic cells, and T cells. These cells release pro-inflammatory cytokines and chemokines, which recruit other immune cells to the implantation site. The activation of the immune system can lead to an inflammatory response, which can be beneficial or detrimental, depending on the type of natural biomaterial and the extent of the immune response. These biomaterials can also influence the immune response by modulating the behavior of immune cells. For example, biomaterials with specific surface properties, such as charge and hydrophobicity, can affect the activation and differentiation of immune cells. Additionally, biomaterials can be engineered to release immunomodulatory factors, such as anti-inflammatory cytokines, to promote a tolerogenic immune response. In conclusion, the interaction between biomaterials and the body's immune system is an intricate procedure with potential consequences for the effectiveness of therapeutics and medical devices. A better understanding of this interplay can help to design biomaterials that promote favorable immune responses and minimize adverse reactions.

Progress in construction and release of natural polysaccharide-platinum nanomedicines: A review

Natural polysaccharides are natural biomaterials that have become candidate materials for nano-drug delivery systems due to their excellent biodegradability and biocompatibility. Platinum (Pt) drugs have been widely used in the clinical therapy for various solid tumors. However, their extensive systemic toxicity and the drug resistance acquired by cancer cells limit the applications of platinum drugs. Modern nanobiotechnology provides the possibility for targeted delivery of platinum drugs to the tumor site, thereby minimizing toxicity and optimizing the efficacies of the drugs. In recent years, numerous natural polysaccharide-platinum nanomedicine delivery carriers have been developed, such as nanomicelles, nanospheres, nanogels, etc. Herein, we provide an overview on the construction and drug release of natural polysaccharide-Pt nanomedicines in recent years. Current challenges and future prospectives in this field are also put forward. In general, combining with irradiation and tumor microenvironment provides a significant research direction for the construction of natural polysaccharide-platinum nanomedicines and the release of responsive drugs in the future.

Polydopamine-Functionalized Bacterial Cellulose as Hydrogel Scaffolds for Skin Tissue Engineering

Bacterial cellulose (BC) is a natural polysaccharide polymer hydrogel produced sustainably by the strain Gluconacetobacter hansenii under static conditions. Due to their biocompatibility, easy functionalization, and necessary physicochemical and mechanical properties, BC nanocomposites are attracting interest in therapeutic applications. In this study, we functionalized BC hydrogel with polydopamine (PDA) without toxic crosslinkers and used it in skin tissue engineering. The BC nanofibers in the hydrogel had a thickness of 77.8 ± 20.3 nm, and they could be used to produce hydrophilic, adhesive, and cytocompatible composite biomaterials for skin tissue engineering applications using PDA. Characterization techniques, namely Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and Raman spectroscopy, were performed to investigate the formation of polydopamine on the BC nanofibers. The XRD peaks for BC occur at 2θ = 14.65°, 16.69°, and 22.39°, which correspond to the planes of (100), (010), and (110) of cellulose type Iα. Raman spectroscopy confirmed the formation of PDA, as indicated by the presence of bands corresponding to the vibration of aromatic rings and aliphatic C-C and C-O stretching at 1336 and 1567 cm-1, respectively. FTIR confirmed the presence of peaks corresponding to PDA and BC in the BC/PDA hydrogel scaffolds at 3673, 3348, 2900, and 1052 cm-1, indicating the successful interaction of PDA with BC nanofibers, which was further corroborated by the SEM images. The tensile strength, swelling ratio, degradation, and surface wettability characteristics of the composite BC biomaterials were also investigated. The BC/PDA hydrogels with PDA-functionalized BC nanofibers demonstrated excellent tensile strength and water-wetting ability while maintaining the stability of the BC fibers. The enhanced cytocompatibility of the BC/PDA hydrogels was studied using the PrestoBlue assay. Culturing murine NIH/3T3 fibroblasts on BC/PDA hydrogels showed higher metabolic activity and enhanced proliferation. Additionally, it improved cell viability when using BC/PDA hydrogels. Thus, these BC/PDA composite biomaterials can be used as biocompatible natural alternatives to synthetic substitutes for skin tissue engineering and wound-dressing applications.

Polysaccharide-Based Composite Scaffolds for Osteochondral and Enthesis Regeneration

The rotator cuff and Achilles tendons along with the anterior cruciate ligament (ACL) are frequently injured with limited healing capacity. At the soft-hard tissue interface, enthesis is prone to get damaged and its regeneration in osteochondral defects is essential for complete healing. The current clinical techniques used in suturing procedures to reattach tendons to bones need much improvement for the generation of the native interface tissue, that is, enthesis, for patients to regain their full functions. Recently, inspired by the composite native tissue, much effort has been made to fabricate composite scaffolds for enthesis tissue regeneration. This review first focuses on the studies that used composite scaffolds for the regeneration of enthesis. Then, the use of polysaccharides for osteochondral tissue engineering is reviewed and their potential for enthesis regeneration is presented based on their supporting effects on osteogenesis and chondrogenesis. Gellan gum (GG) is selected and reviewed as a promising polysaccharide due to its unique osteogenic and chondrogenic activities that help avoid the inherent weakness of dissimilar materials in composite scaffolds. In addition, original preliminary results showed that GG supports collagen type I production and upregulation of osteogenic marker genes. Impact Statement Enthesis regeneration is essential for complete and functional healing of tendon and ligament tissues. Current suturing techniques to reattach the tendon/ligament to bones have high failure rates. This review highlights the studies on biomimetic scaffolds aimed to regenerate enthesis. In addition, the potential of using polysaccharides to regenerate enthesis is discussed based on their ability to regenerate osteochondral tissues. Gellan gum is presented as a promising biopolymer that can be modified to simultaneously support bone and cartilage regeneration by providing structural continuity for the scaffold.

Role of immediate early genes in the development of salivary gland organoids in polyisocyanopeptide hydrogels

Human salivary gland organoids have opened tremendous possibilities for regenerative medicine in patients undergoing radiotherapy for the treatment of head and neck cancer. However, their clinical translation is greatly limited by the current use of Matrigel for organoid derivation and expansion. Here, we envisage that the use of a fully, synthetic hydrogel based on the oligo (-ethylene glycol) functionalized polymer polyisocyanopeptides (PICs) can provide an environment suitable for the generation and expansion of salivary gland organoids (SGOs) after optimization of PIC polymer properties. We demonstrate that PIC hydrogels decorated with the cell-binding peptide RGD allow SGO formation from salivary gland (SG)-derived stem cells. This self-renewal potential is preserved for only 4 passages. It was found that SGOs differentiated prematurely in PIC hydrogels affecting their self-renewal capacity. Similarly, SGOs show decreased expression of immediate early genes (IEGs) after culture in PIC hydrogels. Activation of multiple signalling pathways involved in IEG expression by β-adrenergic agonist isoproterenol, led to increased stem cell self-renewal capacity as measured by organoid forming efficiency (OFE). These results indicate that PIC hydrogels are promising 3D matrices for SGOs, with the option to be used clinically, after further optimization of the hydrogel and culture conditions.

The therapeutic effect and targets of cellulose polysaccharide on coronary heart disease (CHD) and the construction of a prognostic signature based on network pharmacology

Cellulose is the first rich biological polysaccharide in nature and has many excellent properties, so it is being developed as a variety of drug carriers. Moreover, applications in drug delivery, biosensors/bioanalysis, immobilization of enzymes and cells, stem cell therapy, and skin tissue repair are also highlighted by many studies. Coronary heart disease, as one of the diseases with the highest incidence, is urgent to enhance the survival outcome and life quality of patients with coronary heart disease, whereas the mechanism of cellulose's interaction with the human body remains unclear. However, the mechanism of cellulose's interaction with the human body remains unclear. We obtained 92 genes associated with cellulose and coronary heart disease through the intersection of different databases. Ten key genes were identified: HRAS, STAT3, HSP90AA1, FGF2, VEGFA, CXCR4, TERT, IL2, BCL2L1, and CDK1. Molecular docking of the 10 genes revealed their association with their respective receptors. Analysis by KEGG and GO has discovered that these related targets were more enriched in metabolic- and activation-related functions, which further confirmed that cellulose polysaccharides can also interact with cardiovascular diseases as molecules. In the end, we screened out six key genes that were more associated with the prognosis (CDK1, HSP90AA1, CXCR4, IL2, VEGFA, and TERT) and constructed a signature, which has a good predictive effect and has significant statistical significance. Our study is the first study to explore the interaction targets of cellulose and CHD and to construct a prognostic model. Our findings provide insights for future molecular design, drug development, and clinical trials.

Advances in Scaffolds Used for Pulp-Dentine Complex Tissue Engineering - A Narrative Review

Pulp necrosis in immature teeth disrupts root development and predisposes roots to fracture as a consequence of their thin walls and open apices. Regenerative endodontics is a developing treatment modality whereby necrotic pulps are replaced with newly formed healthy tissue inside the root canal. Many clinical studies have demonstrated the potential of this strategy to stimulate root maturation and apical root-end closure. However, clinical outcomes are patient-dependent and unpredictable. The development of predictable clinical protocols is achieved through the interplay of the three classical elements of tissue engineering, namely, stem cells, signaling molecules, and scaffolds. Scaffolds provide structural support for cells to adhere and proliferate and also regulate cell differentiation and metabolism. Hence, designing and fabricating an appropriate scaffold is a crucial step in tissue engineering. In this review, four main classes of scaffolds used to engineer pulp-dentine complexes, including bioceramic-based scaffolds, synthetic polymer-based scaffolds, natural polymer-based scaffolds, and composite scaffolds, are covered. Additionally, recent advances in the design, fabrication, and application of such scaffolds are analysed along with their advantages and limitations. Finally, the importance of vascular network establishment in the success of pulp-dentine complex regeneration and strategies used to create scaffolds to address this challenge are discussed.

Impact of Kefiran Exopolysaccharide Extraction on Its Applicability for Tissue Engineering and Regenerative Medicine

Kefiran is an exopolysaccharide produced by the microflora of kefir grains used to produce the fermented milk beverage kefir. The health-promoting and physicochemical properties of kefiran led to its exploration for a range of applications, mainly in the food industry and biomedical fields. Aiming to explore its potential for tissue engineering and regenerative medicine (TERM) applications, the kefiran biopolymer obtained through three different extraction methodologies was fully characterized and compared. High-quality kefiran polysaccharides were recovered with suitable yield through different extraction protocols. The methods consisted of heating the kefir grains prior to recovering kefiran by centrifugation and differed mainly in the precipitation steps included before lyophilization. Then, kefiran scaffolds were successfully produced from each extract by cryogelation and freeze-drying. In all extracts, it was possible to identify the molecular structure of the kefiran polysaccharide through ¹H-NMR and FTIR spectra. The kefiran from extraction 1 showed the highest molecular weight (~3000 kDa) and the best rheological properties, showing a pseudoplastic behavior; its scaffold presented the highest value of porosity (93.2% ± 2), and wall thickness (85.8 µm ± 16.3). All extracts showed thermal stability, good injectability and desirable viscoelastic properties; the developed scaffolds demonstrated mechanical stability, elastic behavior, and pore size comprised between 98–94 µm. Additionally, all kefiran products proved to be non-cytotoxic over L929 cells. The interesting structural, physicochemical, and biological properties showed by the kefiran extracts and cryogels revealed their biomedical potential and suitability for TERM applications.

Plant Polysaccharides in Engineered Pharmaceutical Gels

Hydrogels are a great ally in the pharmaceutical and biomedical areas. They have a three-dimensional polymeric structure that allows the swelling of aqueous fluids, acting as an absorbent, or encapsulating bioactive agents for controlled drug release. Interestingly, plants are a source of biogels, specifically polysaccharides, composed of sugar monomers. The crosslinking of these polymeric chains forms an architecture similar to the extracellular matrix, enhancing the biocompatibility of such materials. Moreover, the rich hydroxyl monomers promote a hydrophilic behavior for these plant-derived polysaccharide gels, enabling their biodegradability and antimicrobial effects. From an economic point of view, such biogels help the circular economy, as a green material can be obtained with a low cost of production. As regards the bio aspect, it is astonishingly attractive since the raw materials (polysaccharides from plants-cellulose, hemicelluloses, lignin, inulin, pectin, starch, guar, and cashew gums, etc.) might be produced sustainably. Such properties make viable the applications of these biogels in contact with the human body, especially incorporating drugs for controlled release. In this context, this review describes some sources of plant-derived polysaccharide gels, their biological function, main methods for extraction, remarkable applications, and properties in the health field.

Natural Polymers in Heart Valve Tissue Engineering: Strategies, Advances and Challenges

In the history of biomedicine and biomedical devices, heart valve manufacturing techniques have undergone a spectacular evolution. However, important limitations in the development and use of these devices are known and heart valve tissue engineering has proven to be the solution to the problems faced by mechanical and prosthetic valves. The new generation of heart valves developed by tissue engineering has the ability to repair, reshape and regenerate cardiac tissue. Achieving a sustainable and functional tissue-engineered heart valve (TEHV) requires deep understanding of the complex interactions that occur among valve cells, the extracellular matrix (ECM) and the mechanical environment. Starting from this idea, the review presents a comprehensive overview related not only to the structural components of the heart valve, such as cells sources, potential materials and scaffolds fabrication, but also to the advances in the development of heart valve replacements. The focus of the review is on the recent achievements concerning the utilization of natural polymers (polysaccharides and proteins) in TEHV; thus, their extensive presentation is provided. In addition, the technological progresses in heart valve tissue engineering (HVTE) are shown, with several inherent challenges and limitations. The available strategies to design, validate and remodel heart valves are discussed in depth by a comparative analysis of in vitro, in vivo (pre-clinical models) and in situ (clinical translation) tissue engineering studies.

Synthesis and Characterization of Regioselectively Functionalized Mono-Sulfated and -Phosphorylated Anionic Poly-Amido-Saccharides

Polysaccharides are abundant in nature and employed in various biomedical applications ranging from scaffolds for tissue engineering to carriers for drug delivery systems. However, drawbacks such as tedious isolation protocols, contamination, batch-to-batch consistency, and lack of compositional control with regards to stereo- and regioselectivity impede the development and utility of polysaccharides, and thus mimetics are highly sought after. We report a synthetic strategy to regioselectively functionalize poly-amido-saccharides with sulfate or phosphate groups using post-polymerization modification reactions. Orthogonally protected β-lactam monomers, synthesized from D-glucal, undergo anionic ring-opening polymerization to yield polymers with degrees of polymerization of 12, 25, and 50. Regioselective deprotection followed by functionalization and global deprotection affords the sulfated and phosphorylated poly-amido-saccharides. The resulting anionic polymers are water soluble and non-cytotoxic and adopt helical conformations. This new methodology provides access to otherwise inaccessible functional polysaccharide mimetics for biomedical applications.

Recent Advances in Development of Natural Cellulosic Non-Woven Scaffolds for Tissue Engineering

In recent years, tissue engineering researchers have exploited a variety of biomaterials that can potentially mimic the extracellular matrix (ECM) for tissue regeneration. Natural cellulose, mainly obtained from bacterial (BC) and plant-based (PC) sources, can serve as a high-potential scaffold material for different regenerative purposes. Natural cellulose has drawn the attention of researchers due to its advantages over synthetic cellulose including its availability, cost effectiveness, perfusability, biocompatibility, negligible toxicity, mild immune response, and imitation of native tissues. In this article, we review recent in vivo and in vitro studies which aimed to assess the potential of natural cellulose for the purpose of soft (skin, heart, vein, nerve, etc.) and hard (bone and tooth) tissue engineering. Based on the current research progress report, it is sensible to conclude that this emerging field of study is yet to satisfy the clinical translation criteria, though reaching that level of application does not seem far-fetched.

Scaffolds for Cultured Meat on the Basis of Polysaccharide Hydrogels Enriched with Plant-Based Proteins

The world population is growing and alternative ways of satisfying the increasing demand for meat are being explored, such as using animal cells for the fabrication of cultured meat. Edible biomaterials are required as supporting structures. Hence, we chose agarose, gellan and a xanthan-locust bean gum blend (XLB) as support materials with pea and soy protein additives and analyzed them regarding material properties and biocompatibility. We successfully built stable hydrogels containing up to 1% pea or soy protein. Higher amounts of protein resulted in poor handling properties and unstable gels. The gelation temperature range for agarose and gellan blends is between 23-30 °C, but for XLB blends it is above 55 °C. A change in viscosity and a decrease in the swelling behavior was observed in the polysaccharide-protein gels compared to the pure polysaccharide gels. None of the leachates of the investigated materials had cytotoxic effects on the myoblast cell line C2C12. All polysaccharide-protein blends evaluated turned out as potential candidates for cultured meat. For cell-laden gels, the gellan blends were the most suitable in terms of processing and uniform distribution of cells, followed by agarose blends, whereas no stable cell-laden gels could be formed with XLB blends.

Membrane Technological Pathways and Inherent Structure of Bacterial Cellulose Composites for Drug Delivery

This report summarizes efforts undertaken in the area of drug delivery, with a look at further efforts made in the area of bacterial cellulose (BC) biomedical applications in general. There are many current methodologies (past and present) for the creation of BC membrane composites custom-engineered with drug delivery functionality, with brief consideration for very close applications within the broader category of biomedicine. The most emphasis was placed on the crucial aspects that open the door to the possibility of drug delivery or the potential for use as drug carriers. Additionally, consideration has been given to laboratory explorations as well as already established BC-drug delivery systems (DDS) that are either on the market commercially or have been patented in anticipation of future commercialization. The cellulose producing strains, current synthesis and growth pathways, critical aspects and intrinsic morphological features of BC were given maximum consideration, among other crucial aspects of BC DDS.

Ulvan mediated VE cadherin antibody and REDV peptide co-modification to improve endothelialization potential of bioprosthetic heart valves

An aging population and a rapid increase in the incidence of degenerative valve diseases have led to greater use of bioprosthetic heart valves (BHVs). The durability of glutaraldehyde cross-linked bioprostheses currently available for clinical use is poor due to calcification, coagulation, and degradation. Decellularization can partially reduce calcification by removal of xenogenic cells, but can also lead to thrombosis, which can be addressed by further surface modification. The natural sulfated polysaccharide ulvan possesses antithrombotic and anti-inflammatory properties, and can behave as a heparinoid to immobilize proteins through their heparin binding sites. VE-cadherin antibody and the Arg-Glu-Asp-Val (REDV) peptide can facilitate selective endothelial cell attachment, adhesion and proliferation. In this study, we functionalized decellularized porcine pericardium (DPP) with ulvan, REDV, and VE-cadherin antibody (U-R-VE). Ulvan was covalently modified to act as a protective coating and spacer for VE-cadherin antibody, and to immobilize REDV. In in vitro tests, we found that functionalization significantly and selectively promoted adhesion and growth of endothelial cells while reducing platelet adhesion, inflammation, and in vitro calcification of DPPs. In an in vivo subdermal implantation model, U-R-VE modified DPP exhibited greater endothelialization potential and biocompatibility compared with unmodified pericardium. Thus, U-R-VE modification provides a promising solution to the problem of preparing BHVs with enhanced endothelialization potential.

The Study of Physicochemical Properties and Blood Compatibility of Sodium Alginate-Based Materials via Tannic Acid Addition

In this study, sodium alginate-based thin films were modified by the addition of tannic acid. Materials were obtained by solvent evaporation. They were characterized by the observation of its morphology and its surface by scanning electron microscope and atomic force microscope. The thermal properties were studied by differential scanning calorimetry. The concentration of tannic acid released from the material was determined by the Folin–Ciocalteu method. The material safety for biomedical application was determined by the hemolysis rate study in contact with sheep blood as well as platelet adhesion to the material surface. Based on the obtained results, we assume that proposed films based on sodium alginate/tannic acid are safe and may potentially find application in medicine.

Dual effects of atorvastatin on angiogenesis pathways in the differentiation of mesenchymal stem cells

Atorvastatin (ATO) can improve the transplantation efficacy of mesenchymal stem cells (MSCs) after acute myocardial infarction. The present study aimed at ATO effects on the angiogenesis-signaling pathways from MSCs' differentiation to tissue angiogenesis. MSCs were first prepared from BALB/c mouse bone marrow. MTT assay was then done for the biodegradability of MSCs with the extracellular matrix. After that, the differentiation of cells into the bone and fat tissues was confirmed by Alizarin and Oil Red O staining. The extracellular matrix was then combined with the cells to the implant. Animals were intraperitoneally treated with ATO (2 and 40 mg/kg, daily) three days before cell transplantation to one week after. Finally, the assays were carried out by electron microscopy, immunocytochemistry, ELISA, Western blot, and RT-qPCR techniques. A phase-contrast microscope confirmed the morphology of cells. The cell differentiation into bone and fat tissues was confirmed by Alizarin red staining and flow cytometry, and the cell proliferation was confirmed by MTT assay. Unlike ATO 40 mg/kg group, ATO 2 mg/kg was significantly increased the CD31, eNOS, podocalyxin, von Willibrand factor, and alpha-smooth muscle actin proteins levels compared to the control group in vitro experiment. The expression of CD31 and VEGF proteins, as angiogenesis markers, and Ki-67 protein, as a proliferation marker, was significantly higher in a low dose of ATO (2 mg/kg) than that of the control group in vivo experiment. Unlike ATO 40 mg/kg, the expression levels of ERK, AKT, NF-ҝB, Rho, STAT3, Ets-1, HIF-1α, and VEGF proteins and genes were significantly increased in ATO 2 mg/kg compared to the control. A low dose of ATO can be a beneficial tool in the function of MSCs and their differentiation to tissue angiogenesis.

Polysaccharide-based skin scaffolds with enhanced mechanical compatibility with native human skin

We report a custom-made technique to synthesize process-convenient skin scaffolds by tuning the mechanical properties of hydrogels based on a few naturally occurring polysaccharides to match the rheological properties of previously established benchmarks, i.e., the ex vivo native human skins. We studied the mechanical parameters using oscillatory shear rheology. At small strain amplitudes, the intrinsic elastic modulus showed an almost linear dependence in the middle and a changing rate profile at the two ends with concentration of the principal hydrogel component variant, i.e., kappa (κ)-carrageenan. At large strain amplitudes, the hydrogels demonstrated intercycle strain-softening behavior, the onset of which was directly proportional to the κ-carrageenan concentration. We observed a concentration match for the intrinsic elastic modulus of the benchmark within this sigmoidal curve fit. Contextually, we need to explore other potent polymeric hydrogel systems to achieve mechanical affinity in terms of multiple rheological parameters derived from both strain amplitude and angular frequency sweeps. Additionally, we carried out diffusion experiments to study caffeine permeation attributes. The hydrogels show improved barrier features with increasing κ-carrageenan concentration. In terms of the penetration flux and total cumulative amount of permeated caffeine, this enhanced mechanical adherence demonstrates comparable penetration features with the commercial 3D skin model.

Glycans in scaffold design in tissue reconstruction

Development of an artificial tissue by tissue engineering is witnessed to be one of the long lasting clarified solutions for the damaged tissue function restoration. To accomplish this, a scaffold is designed as a cell carrier in which the extracellular matrix (ECM) performs a prominent task of controlling the inoculated cell’s destiny. ECM composition, topography and mechanical properties lead to different types of interactions between cells and ECM components that trigger an assortment of cellular reactions via diverse sensing mechanisms and downstream signaling pathways. The polysaccharides in the form of proteoglycans and glycoproteins yield better outcomes when included in the designed matrices. Glycosaminoglycan (GAG) chains present on proteoglycans show a wide range of operations such as sequestering of critical effector morphogens which encourage proficient nutrient contribution toward the growing stem cells for their development and endurance. In this review we discuss how the glycosylation aspects are of considerable importance in everyday housekeeping functions of a cell especially when placed in a controlled environment under ideal growth conditions. Hydrogels made from these GAG chains have been used extensively as a resorbable material that mimics the natural ECM functions for an efficient control over cell attachment, permeability, viability, proliferation, and differentiation processes. Also the incorporation of non-mammalian polysaccharides can elicit specific receptor responses which authorize the creation of numerous vigorous frameworks while prolonging the low cost and immunogenicity of the substance.

Tissue engineering of collagen scaffolds crosslinked with plant based polysaccharides

Ideally, a bioscaffold should mimic the characteristics of an extracellular matrix of a living organ of interest. The present study deals with the formation of composite scaffolds of collagen with gum arabic. Collagen was cross-linked with oxidized gum arabic having aldehyde groups to form a porous block. By changing the oxidation level of gum arabic, incorporation of the polysaccharides into the scaffold could be varied resulting in scaffolds with variable polysaccharide to protein content. A series of scaffolds were made by altering collagen concentration and oxidation level of gum arabic. The scaffolds were tested for their physical properties, stability, biocompatibility and ability to support the cell growth. Results implied that variable polysaccharide incorporation into the scaffolds was possible depending on the oxidation level of gum arabic which could influence the swelling behavior. The scaffolds showed non-toxic behavior towards the mesenchymal stem cells and nucleus pulposa cells using viability assay in culture conditions up to 30 days; the growth of cells was seen at all combinations of gels. Nucleus pulposa cells were able to maintain their phenotype in the GACO gels. The studies show that these scaffolds are potential candidates in applications, such as tissue engineering, and can be designed to match the requirement of different cell/tissues as per their ECM.

Polysaccharide-Based Biomaterials in Tissue Engineering: A Review

In addition to proteins and nucleic acids, polysaccharides are an important type of biomacromolecule widely distributed in plants, animals, and microorganisms. Polysaccharides are considered as promising biomaterials due to their significant bioactivities, natural abundance, immunoactivity, and chemical modifiability for tissue engineering (TE) applications. Due to the similarities of the biochemical properties of polysaccharides and the extracellular matrix of human bodies, polysaccharides are increasingly recognized and accepted. Furthermore, the degradation behavior of these macromolecules is generally nontoxic. Certain delicate properties, such as remarkable mechanical properties and tunable tissue response, can be obtained by modifying the functional groups on the surface of polysaccharide molecules. The applications of polysaccharide-based biomaterials in the TE field have been growing intensively in recent decades, for example, bone/cartilage regeneration, cardiac regeneration, neural regeneration, and skin regeneration. This review summarizes the main essential properties of polysaccharides, including their chemical properties, crosslinking mechanisms, and biological properties, and focuses on the association between their structures and properties. The recent progress in polysaccharide-based biomaterials in various TE applications is reviewed, and the prospects for future studies are addressed as well. We intend this review to offer a comprehensive understanding of and inspiration for the research and development of polysaccharide-based materials in TE.

Differentiation of adipose tissue-derived stem cells towards vascular smooth muscle cells on modified poly(L-lactide) foils

The aim of our research was to study the behaviour of adipose tissue-derived stem cells (ADSCs) and vascular smooth muscle cells (VSMCs) on variously modified poly(L-lactide) (PLLA) foils, namely on pristine PLLA, plasma-treated PLLA, PLLA grafted with polyethylene glycol (PEG), PLLA grafted with dextran (Dex), and the tissue culture polystyrene (PS) control. On these materials, the ADSCs were biochemically differentiated towards VSMCs by a medium supplemented with TGFβ1, BMP4 and ascorbic acid (i.e. differentiation medium). ADSCs cultured in a non-differentiation medium were used as a negative control. Mature VSMCs cultured in both types of medium were used as a positive control. The impact of the variously modified PLLA foils and/or differences in the composition of the medium were studied with reference to cell adhesion, growth and differentiation. We observed similar adhesion and growth of ADSCs on all PLLA samples when they were cultured in the non-differentiation medium. The differentiation medium supported the expression of specific early, mid-term and/or late markers of differentiation (i.e. type I collagen, αSMA, calponin, smoothelin, and smooth muscle myosin heavy chain) in ADSCs on all tested samples. Moreover, ADSCs cultured in the differentiation medium revealed significant differences in cell growth among the samples that were similar to the differences observed in the cultures of VSMCs. The round morphology of the VSMCs indicated worse adhesion to pristine PLLA, and this sample was also characterized by the lowest cell proliferation. Culturing VSMCs in the differentiation medium inhibited their metabolic activity and reduced the cell numbers. Both cell types formed the most stable monolayer on plasma-treated PLLA and on the PS control. The behaviour of ADSCs and VSMCs on the tested PLLA foils differed according to the specific cell type and culture conditions. The suitable biocompatibility of both cell types on the tested PLLA foils seems to be favourable for vascular tissue engineering purposes.

Modified tamarind kernel polysaccharide-based matrix alters neuro-keratinocyte cross-talk and serves as a suitable scaffold for skin tissue engineering

Advanced technologies like skin tissue engineering are requisite of various disorders where artificially synthesized materials need to be used as a scaffold in vivo, which in turn can allow the formation of functional skin and epidermal layer with all biological sensory functions. In this work, we present a set of hydrogels which have been synthesized by the method utilizing radical polymerization of a natural polymer extracted from kernel of Tamarindus indica, commonly known as Tamarind Kernel Powder (TKP) modified by utilizing the monomer acrylic acid (AA) in different mole ratios. These materials are termed as TKP: AA hydrogels and characterized by Atomic Force Microscopy (AFM), surface charge, and particle size distribution using Dynamic Light Scattering measurements. These materials are biocompatible with mouse dermal fibroblasts (NIH- 3T3) and human skin keratinocytes (HaCaT), as confirmed by MTT and biocompatibility assays. These TKP: AA hydrogels do not induce unwanted ROS signaling as confirmed by mitochondrial functionality determined by DCFDA staining, Mitosox imaging, and measuring the ATP levels. We demonstrate that in the co-culture system, TKP: AA allows the establishment of proper neuro-keratinocyte contact formation, suggesting that this hydrogel can be suitable for developing skin with sensory functions. Skin corrosion analysis on SD rats confirms that TKP: AA is appropriate for in vivo applications as well. This is further confirmed by in vivo compatibility and toxicity studies, including hemocompatibility and histopathology of liver and kidney upon direct introduction of hydrogel into the body. We propose that TKP: AA (1: 5) offers a suitable surface for skin tissue engineering with sensory functions applicable in vitro, in vivo, and ex vivo. These findings may have broad biomedical and clinical importance.

The effect of agar substrate on growth and development of cryopreserved-thawed human ovarian cortical follicles in organ culture

OBJECTIVE

To preserve human ovarian tissue structure and improve follicular growth and survival during in-situ culture, various biomaterials are used. In this study we aimed to compare agar as a cultivation substrate with matrigel-coated insert in order to achieve an optimum system for in-situ human follicle culture.

STUDY DESIGN

Frozen-thawed human ovarian cortical tissues were cultured on either matrigel-coated inserts or agar-soaked substrates. The proportion of morphologically viable and degenerated follicles at different developmental stages, secreted hormonal levels, and apoptotic and proliferation gene expressions were compared between the cultured groups after 7-days of culture.

RESULTS

The follicular growth was not significantly different between the two cultured groups, although showing higher percentage of growing follicles in agar cultured group. The secreted hormonal levels didn't have any difference between two cultured groups. Although the apoptotic gene expressions didn't show any difference between the cultured groups, the apoptotic index was lower in agar cultured group. In addition, Ki67 gene expression, a proliferative marker, showed a significantly higher expression in agar cultured group.

CONCLUSION

Based on the results, agar is as suitable as matrigel-coated inserts for the survival and growth of follicles during culture. Therefore, agar can be an inexpensive alternative substrate for culturing frozen-thawed human ovarian cortical strips.

Polysaccharide nanoparticles: from fabrication to applications

The present review highlights the developments in polysaccharide nanoparticles with a particular focus on applications in biomedicine, cosmetics and food.

Multiphoton Microscopy for the Characterization of Cellular Behavior on Naturally Derived Polysaccharide Tissue Constructs With Irregular Surfaces for the Development of Platform Biomaterials

Over the past decade, the use of polymers as platform materials for biomedical applications including tissue engineering has been of rising interest. Recently, the use of naturally derived polysaccharides as 3-D scaffolds for tissue regeneration has shown promising material characteristics; however, due to complexities in composition, morphology, and optical properties, adequate spatial and temporal characterization of cellular behavior in these materials is lacking. Multiphoton microscopy has emerged as a viable tool for performing such quantification by permitting greater imaging depth while simultaneously minimizing un-favorable scattering and producing high-resolution optical cross sections for non-invasive analysis. Here we describe a method using endogenous contrast of cellulose nanofibers (CNF) using Second Harmonic Generation (SHG), combined with 2-photon fluorescence of Cell Tracker Orange for spatial and longitudinal imaging of cellular proliferation. Cell Tracker Orange is an ideal fluorophore to avoid the broad CNF autofluorescence allowing for segmentation of cells using a semi-automatic routine. Individual cells were identified using centroid locations for 3D cell proliferation. Overall, the methods presented are viable for investigation of cellular interactions with polysaccharide candidate biomaterials.

3D biofabrication for soft tissue and cartilage engineering

Soft tissue injuries (STIs) affect patients of all age groups and represent a common worldwide clinical problem, resulting from conditions including trauma, infection, cancer and burns. Within the spectrum of STIs a mixture of tissues can be injured, ranging from skin to underlying nerves, blood vessels, tendons and cartilaginous tissues. However, significant limitations affect current treatment options and clinical demand for soft tissue and cartilage regenerative therapies continues to rise. Improving the regeneration of soft tissues has therefore become a key area of focus within tissue engineering. As an emerging technology, 3D bioprinting can be used to build complex soft tissue constructs "from the bottom up," by depositing cells, growth factors, extracellular matrices and other biomaterials in a layer-by-layer fashion. In this way, regeneration of cartilage, skin, vasculature, nerves, tendons and other bodily tissues can be performed in a patient specific manner. This review will focus on recent use of 3D bioprinting and other biofabrication strategies in soft tissue repair and regeneration. Biofabrication of a variety of soft tissue types will be reviewed following an overview of available cell sources, bioinks and bioprinting techniques.

Cellulose Nanofibril Hydrogel Promotes Hepatic Differentiation of Human Liver Organoids

To replicate functional liver tissue in vitro for drug testing or transplantation, 3D tissue engineering requires representative cell models as well as scaffolds that not only promote tissue production but also are applicable in a clinical setting. Recently, adult liver-derived liver organoids are found to be of much interest due to their genetic stability, expansion potential, and ability to differentiate toward a hepatocyte-like fate. The current standard for culturing these organoids is a basement membrane hydrogel like Matrigel (MG), which is derived from murine tumor material and apart from its variability and high costs, possesses an undefined composition and is therefore not clinically applicable. Here, a cellulose nanofibril (CNF) hydrogel is investigated with regard to its potential to serve as an alternative clinical grade scaffold to differentiate liver organoids. The results show that its mechanical properties are suitable for differentiation with overall, either equal or improved, functionality of the hepatocyte-like cells compared to MG. Therefore, and because of its defined and tunable chemical definition, the CNF hydrogel presents a viable alternative to MG for liver tissue engineering with the option for clinical use.

Pullulan/Poly(Vinyl Alcohol) Composite Hydrogels for Adipose Tissue Engineering

Composite hydrogels based on pullulan (HP) and poly(vinyl alcohol) (PVA) were both prepared by simple chemical crosslinking with sodium trimethaphosphate (STMP) or by dual crosslinking (simultaneously chemical crosslinking with STMP and physical crosslinking by freeze-thaw technique). The resulting hydrogels and cryogels were designed for tissue engineering applications. PVA, with two different molecular weights (47,000 and 125,000 g/mol; PVA₄₇ and PVA₁₂₅, respectively), as well as different P/PVA weight ratios were tested. The physico-chemical characterization of the hydrogels was performed by FTIR spectroscopy and scanning electron microscopy (SEM). The swelling kinetics, dissolution behavior, and degradation profiles in simulated physiological conditions (phosphate buffer at pH 7.4) were investigated. Pullulan concentration and the crosslinking method had significant effects on the pore size, swelling ratio, and degradation profiles. Cryogels exhibit lower swelling capacities than the conventional hydrogels but have better stability against hydrolitic degradation. Biocompatibility of the hydrogels was also investigated by both MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and LDH (lactaten dehydrogenase) assay. The MTT and LDH assays proved that dual crosslinked HP/PVA₁₂₅ (75:25, w/w) scaffolds are more biocompatible and promote to a greater extent the adhesion and proliferation of L929 murine fibroblast cells than chemically crosslinked HP/PVA₄₇ (50/50, w/w) scaffolds. Moreover, the HP/PVA₁₂₅ cryogel had the best ability for the adipogenic differentiation of cells. The overall results demonstrated that the HP/PVA composite hydrogels or cryogels are suitable biomaterials for tissue engineering applications.

Overviews of Biomimetic Medical Materials

This chapter describes the overviews of biomimetic medical materials which covers innovation and significance of terminology, diverse fabrication methods, and technologies ranges from nanotechnology to 3D printing to develop biomimetic materials for medical applications. It also depicts specific fundamental characteristics required for a material to be a model biomimetic material for particular medical application. It basically outlines current statuses of biomimetic medical materials used for tissue engineering and regenerative medicine, drug/protein delivery, bioimaging, biosensing, and 3D bioprinting technology. It also illustrates the effect of functionalization of a material through chemical and biological approaches towards different applications. Not only, the key properties and potential applications of the biomimetic materials, but it also explains the protection and utilization of intellectual property associated with biomedical materials.

Gelatin-polysaccharide composite scaffolds for 3D cell culture and tissue engineering: Towards natural therapeutics

Gelatin is a promising material as scaffold with therapeutic and regenerative characteristics due to its chemical similarities to the extracellular matrix (ECM) in the native tissues, biocompatibility, biodegradability, low antigenicity, cost-effectiveness, abundance, and accessible functional groups that allow facile chemical modifications with other biomaterials or biomolecules. Despite the advantages of gelatin, poor mechanical properties, sensitivity to enzymatic degradation, high viscosity, and reduced solubility in concentrated aqueous media have limited its applications and encouraged the development of gelatin-based composite hydrogels. The drawbacks of gelatin may be surmounted by synergistically combining it with a wide range of polysaccharides. The addition of polysaccharides to gelatin is advantageous in mimicking the ECM, which largely contains proteoglycans or glycoproteins. Moreover, gelatin-polysaccharide biomaterials benefit from mechanical resilience, high stability, low thermal expansion, improved hydrophilicity, biocompatibility, antimicrobial and anti-inflammatory properties, and wound healing potential. Here, we discuss how combining gelatin and polysaccharides provides a promising approach for developing superior therapeutic biomaterials. We review gelatin-polysaccharides scaffolds and their applications in cell culture and tissue engineering, providing an outlook for the future of this family of biomaterials as advanced natural therapeutics.

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.

3D bioactive composite scaffolds for bone tissue engineering

Bone is the second most commonly transplanted tissue worldwide, with over four million operations using bone grafts or bone substitute materials annually to treat bone defects. However, significant limitations affect current treatment options and clinical demand for bone grafts continues to rise due to conditions such as trauma, cancer, infection and arthritis. Developing bioactive three-dimensional (3D) scaffolds to support bone regeneration has therefore become a key area of focus within bone tissue engineering (BTE). A variety of materials and manufacturing methods including 3D printing have been used to create novel alternatives to traditional bone grafts. However, individual groups of materials including polymers, ceramics and hydrogels have been unable to fully replicate the properties of bone when used alone. Favourable material properties can be combined and bioactivity improved when groups of materials are used together in composite 3D scaffolds. This review will therefore consider the ideal properties of bioactive composite 3D scaffolds and examine recent use of polymers, hydrogels, metals, ceramics and bio-glasses in BTE. Scaffold fabrication methodology, mechanical performance, biocompatibility, bioactivity, and potential clinical translations will be discussed.

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.

Smart Carriers and Nanohealers: A Nanomedical Insight on Natural Polymers

Biodegradable polymers are popularly being used in an increasing number of fields in the past few decades. The popularity and favorability of these materials are due to their remarkable properties, enabling a wide range of applications and market requirements to be met. Polymer biodegradable systems are a promising arena of research for targeted and site-specific controlled drug delivery, for developing artificial limbs, 3D porous scaffolds for cellular regeneration or tissue engineering and biosensing applications. Several natural polymers have been identified, blended, functionalized and applied for designing nanoscaffolds and drug carriers as a prerequisite for enumerable bionano technological applications. Apart from these, natural polymers have been well studied and are widely used in material science and industrial fields. The present review explains the prominent features of commonly used natural polymers (polysaccharides and proteins) in various nanomedical applications and reveals the current status of the polymer research in bionanotechnology and science sectors.

Investigation of the effects of starch on the physical and biological properties of polyacrylamide (PAAm)/starch nanofibers

Here, we report the development of a new polyacrylamide (PAAm)/starch nanofibers’ blend system and highlight its potential as substrate for efficient enzyme immobilization. PAAm was synthesized and blended with starch. The final blend was then electrospun into nanofibers. The response surface methodology was used to analyze the parameters that control nanofiber’s diameter. Electrospun mat was then modified either by cross-linking or phytase immobilization using silane coupling agent and glutaraldehyde chemistry. Physico-chemical properties of blends were investigated using spectroscopic and thermal studies. The evaluation of immobilized enzyme kinetics on both pure and the starch blended PAAm nanofibers was performed using Michaelis–Menten kinetic curves. Fourier transform infrared spectroscopy results along with differential scanning and X-ray diffraction confirmed that blending was successfully accomplished. TGA analysis also demonstrated that the presence of starch enhances the thermal degradability of PAAm nanofibers. Finally, it was shown that addition of starch to PAAm increases the efficacies of enzyme loading and, therefore, significantly enhances the activity as well as kinetics of the immobilized enzyme on electrospun blend mats.

Design and fabrication of porous biodegradable scaffolds: a strategy for tissue engineering

Current strategies of tissue engineering are focused on the reconstruction and regeneration of damaged or deformed tissues by grafting of cells with scaffolds and biomolecules. Recently, much interest is given to scaffolds which are based on mimic the extracellular matrix that have induced the formation of new tissues. To return functionality of the organ, the presence of a scaffold is essential as a matrix for cell colonization, migration, growth, differentiation and extracellular matrix deposition, until the tissues are totally restored or regenerated. A wide variety of approaches has been developed either in scaffold materials and production procedures or cell sources and cultivation techniques to regenerate the tissues/organs in tissue engineering applications. This study has been conducted to present an overview of the different scaffold fabrication techniques such as solvent casting and particulate leaching, electrospinning, emulsion freeze-drying, thermally induced phase separation, melt molding and rapid prototyping with their properties, limitations, theoretical principles and their prospective in tailoring appropriate micro-nanostructures for tissue regeneration applications. This review also includes discussion on recent works done in the field of tissue engineering.

Biocompatible agarose-chitosan coated silver nanoparticle composite for soft tissue engineering applications

With increasing gap in the demand and supply of vital organs for transplantation there is a pressing need to bridge the gap with substitutes. One way to make substitutes is by tissue engineering which involves combining several types of synthetic or biomaterials, cells and growth factors cross-linked together to synthesize a functional scaffold for repair or replacement of non-functional organs. Nanoparticle based composites are gaining importance in tissue engineering due to their ability to enhance cell attachment and proliferation. The current study focuses on synthesizing agarose composites embedded with chitosan-coated silver nanoparticles using glutaraldehyde as the cross-linker. The synthesis of chitosan coated silver nanoparticles within the scaffold was confirmed with UV-visible spectroscopy. Physical and chemical characterization of the synthesized nanoparticles were done by XRD, FTIR, TGA and SEM. DMA showed higher mechanical strength of the scaffolds. The scaffolds showed degradation of ∼37% within a span of four weeks. The higher physical support provided by the synthesized scaffolds was shown by in-vitro cell viability assay. Broad spectrum anti-bacterial activity and superior hemocompatibility further showed the advantage it offered for growing cells. Thus a biopolymer based nanocomposite was synthesized, with intended widespread use as scaffold for engineering of soft tissues due to its enhanced biocompatibility and greater surface area for cell growth.