Cellulose Biomaterials for Tissue Engineering

Recent advances in plant-derived polysaccharide scaffolds in tissue engineering: A review

As a natural three-dimensional biopolymer, decellularized plant-derived scaffolds usually comprise various polysaccharides, mostly cellulose, pectin, and hemicellulose. They are characterized by natural biocompatibility and porous structures. The emergence of decellularized purified polysaccharide scaffolds provides an attractive method to overcome the challenges associated with nutrient delivery and biocompatibility, as they serve as optimal non-immune environments for stem cell adhesion and proliferation. To date, limited corresponding literature is available to systemically summarize the development and potential of these scaffolds in tissue engineering. Therefore, the current review summarized the biomimetic properties of plant-derived polysaccharide scaffolds and the latest progress in tissue engineering applications. This review first discusses the advantages of decellularized plant-derived polysaccharide scaffolds by briefly introducing their features and current limitations in clinical applications. Subsequently, the latest progress in emerging applications of regenerative biomaterials is reviewed, followed by a discussion of the studies on the interactions of biomaterials with cells and tissues. Finally, challenges in obtaining reliable scaffolds and possible future directions are discussed.

Generation of Chicken Contractile Skeletal Muscle Structure Using Decellularized Plant Scaffolds

Cultured meat is a meat analogue produced by in vitro cell culture, which can replace the conventional animal production system. Tissue engineering using myogenic cells and biomaterials is a core technology for cultured meat production. In this study, we provide an efficient and economical method to produce skeletal muscle tissue-like structures by culturing chicken myoblasts in a fetal bovine serum (FBS)-free medium and plant-derived scaffolds. An FBS-free medium supplemented with 10% horse serum (HS) and 5% chick embryo extract (CEE) was suitable for the proliferation and differentiation of chicken myoblasts. Decellularized celery scaffolds (Decelery), manufactured using 1% sodium dodecyl sulfate (SDS), were nontoxic to cells and supported myoblast proliferation and differentiation. Decelery could support the 3D culture of chicken myoblasts, which could adhere and coagulate to the surface of the Decelery and form MYH1E+ and F-actin+ myotubes. After 2 weeks of culture on Decelery, fully grown myoblasts completely covered the surface of the scaffolds and formed fiber-like myotube structures. They further differentiated to form spontaneously contracting myofiber-like myotubes on the scaffold surface, indicating that the Decelery scaffold system could support the formation of a functional mature myofiber structure. In addition, as the spontaneously contracting myofibers did not detach from the surface of the Decelery, the Decelery system is a suitable biomaterial for the long-term culture and maintenance of the myofiber structures.

Plant Decellularization by Chemical and Physical Methods for Regenerative Medicine: A Review Article

Fabricating three-dimensional (3D) scaffolds is attractive due to various advantages for tissue engineering, such as cell migration, proliferation, and adhesion. Since cell growth depends on transmitting nutrients and cell residues, naturally vascularized scaffolds are superior for tissue engineering. Vascular passages help the inflow and outflow of liquids, nutrients, and waste disposal from the scaffold and cell growth. Porous scaffolds can be prepared by plant tissue decellularization which allows for the cultivation of various cell lines depending on the intended application. To this end, researchers decellularize plant tissues by specific chemical and physical methods. Researchers use plant parts depending on their needs, for example, decellularizing the leaves, stems, and fruits. Plant tissue scaffolds are advantageous for regenerative medicine, wound healing, and bioprinting. Studies have examined various plants such as vegetables and fruits such as orchid, parsley, spinach, celery, carrot, and apple using various materials and techniques such as sodium dodecyl sulfate, Triton X-100, peracetic acid, deoxyribonuclease, and ribonuclease with varying percentages, as well as mechanical and physical techniques like freeze-thaw cycles. The process of data selection, retrieval, and extraction in this review relied on scholarly journal publications and other relevant papers related to the subject of decellularization, with a specific emphasis on plant-based research. The obtained results indicate that, owing to the cellulosic structure and vascular nature of the decellularized plants and their favorable hydrophilic and biological properties, they have the potential to serve as biological materials and natural scaffolds for the development of 3D-printing inks and scaffolds for tissue engineering.

Application of pulsed electric field technology to skin engineering

Tissue engineering encompasses a range of techniques that direct the growth of cells into a living tissue construct for regenerative medicine applications, disease models, drug discovery, and safety testing. These techniques have been implemented to alleviate the clinical burdens of impaired healing of skin, bone, and other tissues. Construct development requires the integration of tissue-specific cells and/or an extracellular matrix-mimicking biomaterial for structural support. Production of such constructs is generally expensive and environmentally costly, thus eco-sustainable approaches should be explored. Pulsed electric field (PEF) technology is a nonthermal physical processing method commonly used in food production and biomedical applications. In this review, the key principles of PEF and the application of PEF technology for skin engineering will be discussed, with an emphasis on how PEF can be applied to skin cells to modify their behaviour, and to biomaterials to assist in their isolation or sterilisation, or to modify their physical properties. The findings indicate that the success of PEF in tissue engineering will be reliant on systematic evaluation of key parameters, such as electric field strength, and their impact on different skin cell and biomaterial types. Linking tangible input parameters to biological responses critical to healing will assist with the development of PEF as a sustainable tool for skin repair and other tissue engineering applications.

Graph Network-Based Simulation of Multicellular Dynamics Driven by Concentrated Polymer Brush-Modified Cellulose Nanofibers

Manipulating the three-dimensional (3D) structures of cells is important for facilitating to repair or regenerate tissues. A self-assembly system of cells with cellulose nanofibers (CNFs) and concentrated polymer brushes (CPBs) has been developed to fabricate various cell 3D structures. To further generate tissues at an implantable level, it is necessary to carry out a large number of experiments using different cell culture conditions and material properties; however this is practically intractable. To address this issue, we present a graph-neural network-based simulator (GNS) that can be trained by using assembly process images to predict the assembly status of future time steps. A total of 24 (25 steps) time-series images were recorded (four repeats for each of six different conditions), and each image was transformed into a graph by regarding the cells as nodes and the connecting neighboring cells as edges. Using the obtained data, the performances of the GNS were examined under three scenarios (i.e., changing a pair of the training and testing data) to verify the possibility of using the GNS as a predictor for further time steps. It was confirmed that the GNS could reasonably reproduce the assembly process, even under the toughest scenario, in which the experimental conditions differed between the training and testing data. Practically, this means that the GNS trained by the first 24 h images could predict the cell types obtained 3 weeks later. This result could reduce the number of experiments required to find the optimal conditions for generating cells with desired 3D structures. Ultimately, our approach could accelerate progress in regenerative medicine.

Advances in Polysaccharides for Cartilage Tissue Engineering Repair: A Review

Cartilage repair has been a significant challenge in orthopedics that has not yet been fully resolved. Due to the absence of blood vessels and the almost cell-free nature of mature cartilage tissue, the limited ability to repair cartilage has resulted in significant socioeconomic pressures. Polysaccharide materials have recently been widely used for cartilage tissue repair due to their excellent cell loading, biocompatibility, and chemical modifiability. They also provide a suitable microenvironment for cartilage repair and regeneration. In this Review, we summarize the techniques used clinically for cartilage repair, focusing on polysaccharides, polysaccharides for cartilage repair, and the differences between these and other materials. In addition, we summarize the techniques of tissue engineering strategies for cartilage repair and provide an outlook on developing next-generation cartilage repair and regeneration materials from polysaccharides. This Review will provide theoretical guidance for developing polysaccharide-based cartilage repair and regeneration materials with clinical applications for cartilage tissue repair and regeneration.

Magnetic biocomposite scaffold based on decellularized tendon ECM and MNP-deposited halloysite nanotubes: physicochemical, thermal, rheological, mechanical andin vitrobiological evaluations

The development of new three-dimensional biomaterials with advanced versatile properties is critical to the success of tissue engineering (TE) applications. Here, (a) bioactive decellularized tendon extracellular matrix (dECM) with a sol-gel transition feature at physiological temperature, (b) halloysite nanotubes (HNT) with known mechanical properties and bioactivity, and (c) magnetic nanoparticles (MNP) with superparamagnetic and osteogenic properties were combined to develop a new scaffold that could be used in prospective bone TE applications. Deposition of MNPs on HNTs resulted in magnetic nanostructures without agglomeration of MNPs. A completely cell-free, collagen- and glycosaminoglycan- rich dECM was obtained and characterized. dECM-based scaffolds incorporated with 1%, 2% and 4% MNP-HNT were analysed for their physical, chemical, andin vitrobiological properties. Fourier-transform infrared spectroscopy, x-ray powder diffractometry and vibrating sample magnetometry analyses confirmed the presence of dECM, HNT and MNP in all scaffold types. The capacity to form apatite layer upon incubation in simulated body fluid revealed that dECM-MNP-HNT is a bioactive material. Combining dECM with MNP-HNT improved the thermal stability and compressive strength of the macroporous scaffolds upto 2% MNP-HNT.In vitrocytotoxicity and hemolysis experiments showed that the scaffolds were essentially biocompatible. Human bone marrow mesenchymal stem cells adhered and proliferated well on the macroporous constructs containing 1% and 2% MNP-HNT; and remained metabolically active for at least 21 din vitro. Collectively, the findings support the idea that magnetic nanocomposite dECM scaffolds containing MNP-HNT could be a potential template for TE applications.

A state-of-the-art review on plant-derived cellulose-based green hydrogels and their multifunctional role in advanced biomedical applications

The most prevalent carbohydrate on Earth is cellulose, a polysaccharide composed of glucose units that may be found in diverse sources, such as cell walls of wood and plants and some bacterial and algal species. The inherent availability of this versatile material provides a natural pathway for exploring and identifying novel uses. This study comprehensively analyzes cellulose and its derivatives, exploring their structural and biochemical features and assessing their wide-ranging applications in tissue fabrication, surgical dressings, and pharmaceutical delivery systems. The use of diverse cellulose particles as fundamental components gives rise to materials with distinct microstructures and characteristics, fulfilling the requirements of various biological applications. Although cellulose boasts substantial potential across various sectors, its exploration has predominantly unfolded within industrial realms, leaving the biomedical domain somewhat overlooked in its initial stages. This investigation, therefore, endeavors to shed light on the contemporary strides made in synthesizing cellulose and its derivatives. These innovative techniques give rise to distinctive attributes, presenting a treasure trove of advantages for their compelling integration into the intricate tapestry of biomedical applications.

Biomimetic Exogenous "Tissue Batteries" as Artificial Power Sources for Implantable Bioelectronic Devices Manufacturing

Implantable bioelectronic devices (IBDs) have gained attention for their capacity to conformably detect physiological and pathological signals and further provide internal therapy. However, traditional power sources integrated into these IBDs possess intricate limitations such as bulkiness, rigidity, and biotoxicity. Recently, artificial "tissue batteries" (ATBs) have diffusely developed as artificial power sources for IBDs manufacturing, enabling comprehensive biological-activity monitoring, diagnosis, and therapy. ATBs are on-demand and designed to accommodate the soft and confining curved placement space of organisms, minimizing interface discrepancies, and providing ample power for clinical applications. This review presents the near-term advancements in ATBs, with a focus on their miniaturization, flexibility, biodegradability, and power density. Furthermore, it delves into material-screening, structural-design, and energy density across three distinct categories of TBs, distinguished by power supply strategies. These types encompass innovative energy storage devices (chemical batteries and supercapacitors), power conversion devices that harness power from human-body (biofuel cells, thermoelectric nanogenerators, bio-potential devices, piezoelectric harvesters, and triboelectric devices), and energy transfer devices that receive and utilize external energy (radiofrequency-ultrasound energy harvesters, ultrasound-induced energy harvesters, and photovoltaic devices). Ultimately, future challenges and prospects emphasize ATBs with the indispensability of bio-safety, flexibility, and high-volume energy density as crucial components in long-term implantable bioelectronic devices.

Cellulose nanocrystals from marine algae Cladophora glomerata by using microwave-assisted extraction

Algae of the order Cladophorales are the source of a unique nanocellulose with high crystallinity and a large aspect ratio, enabling broad surface modification. Cellulose nanocrystals (CNCs) are obtained via acid hydrolysis of nanocellulose, which is highly crystalline. However, the production of CNCs from Cladophorales algae is limited and still uses a conventional heating method. Thus, this study aimed to develop a microwave-assisted extraction (MAE) method for fast and efficient extraction of CNCs from Cladophora glomerata algae. Additionally, we replaced the use of hypochlorite with H2O2, which is more environmentally friendly, and compared the CNCs obtained from the conventional methods with our new method. The functional structure of CNCs was confirmed by Fourier-transform infrared spectroscopy. Single-step H2O2 bleaching with MAE yielded the smallest-sized CNCs. Our developed method resulted in the production of CNCs with a high crystallinity index, high thermal stability, and high purity of native cellulose. Additionally, none of the CNCs were toxic to primary normal human dermal fibroblasts. The properties of the isolated CNCs may make them useful materials in pharmaceutical and cosmetic formulations.

Hydrogel-mediated extracellular vesicles for enhanced wound healing: the latest progress, and their prospects for 3D bioprinting

Extracellular vesicles have shown promising tissue recovery-promoting effects, making them increasingly sought-after for their therapeutic potential in wound treatment. However, traditional extracellular vesicle applications suffer from limitations such as rapid degradation and short maintenance during wound administration. To address these challenges, a growing body of research highlights the role of hydrogels as effective carriers for sustained extracellular vesicle release, thereby facilitating wound healing. The combination of extracellular vesicles with hydrogels and the development of 3D bioprinting create composite hydrogel systems boasting excellent mechanical properties and biological activity, presenting a novel approach to wound healing and skin dressing. This comprehensive review explores the remarkable mechanical properties of hydrogels, specifically suited for loading extracellular vesicles. We delve into the diverse sources of extracellular vesicles and hydrogels, analyzing their integration within composite hydrogel formulations for wound treatment. Different composite methods as well as 3D bioprinting, adapted to varying conditions and construction strategies, are examined for their roles in promoting wound healing. The results highlight the potential of extracellular vesicle-laden hydrogels as advanced therapeutic tools in the field of wound treatment, offering both mechanical support and bioactive functions. By providing an in-depth examination of the various roles that these composite hydrogels can play in wound healing, this review sheds light on the promising directions for further research and development. Finally, we address the challenges associated with the application of composite hydrogels, along with emerging trends of 3D bioprinting in this domain. The discussion covers issues such as scalability, regulatory considerations, and the translation of this technology into practical clinical settings. In conclusion, this review underlines the significant contributions of hydrogel-mediated extracellular vesicle therapy to the field of 3D bioprinting and wound healing and tissue regeneration. It serves as a valuable resource for researchers and practitioners alike, fostering a deeper understanding of the potential benefits, applications, and challenges involved in utilizing composite hydrogels for wound treatment.

Random cellulose acetate nanofibers: a breakthrough for cultivated meat production

Overcoming the challenge of creating thick, tissue-resembling muscle constructs is paramount in the field of cultivated meat production. This study investigates the remarkable potential of random cellulose acetate nanofibers (CAN) as a transformative scaffold for muscle tissue engineering (MTE), specifically in the context of cultivated meat applications. Through a comparative analysis between random and aligned CAN, utilizing C2C12 and H9c2 myoblasts, we unveil the unparalleled capabilities of random CAN in facilitating muscle differentiation, independent of differentiation media, by exploiting the YAP/TAZ-related mechanotransduction pathway. In addition, we have successfully developed a novel process for stacking cell-loaded CAN sheets, enabling the production of a three-dimensional meat product. C2C12 and H9c2 loaded CAN sheets were stacked (up to four layers) to form a ~300-400 μm thick tissue 2 cm in length, organized in a mesh of uniaxial aligned cells. To further demonstrate the effectiveness of this methodology for cultivated meat purposes, we have generated thick and viable constructs using chicken muscle satellite cells (cSCs) and random CAN. This groundbreaking discovery offers a cost-effective and biomimetic solution for cultivating and differentiating muscle cells, forging a crucial link between tissue engineering and the pursuit of sustainable and affordable cultivated meat production.

Bacterial cellulose as a promising material for pulmonary valve prostheses: In vivo study in a sheep model

OBJECTIVES

Currently, no consensus exists regarding the most durable prosthesis for pulmonary valve replacement. Bacterial cellulose is a resistant, nonbiodegradable, nonpyrogenic bioimplant with low hemolysis and clotting properties. We hypothesized that bacterial cellulose heart valve prostheses could be an attractive alternative for pulmonary valve replacement.

METHODS

We conducted a large animal model experiment in three adult sheep. The animals underwent open-heart surgery and cardiopulmonary bypass for bacterial cellulose conduit implantation in the pulmonary position. The sheep were followed for seven months, and clinical and laboratory parameters were analyzed. Echocardiographic evaluations were performed at 3 and 7 months. After seven months, the sheep were sacrificed and an autopsy was performed. The explanted conduits were radiologically and histopathologically analyzed.

RESULTS

All sheep survived the operation, showing good recovery and normal health status; no adverse events were noted during the 7-month postoperative follow-up. Interval laboratory findings were normal with no signs of hemolysis or infection. Echocardiographic analysis after 7 months revealed a normal mean pressure gradient with excellent cusp motion and coaptation; a trace of regurgitation was found in two sheep. X-ray analysis of the explanted conduits revealed no structural defects in the leaflets with minimal calcification. Histological examination showed slight thickening of the conduit by pannus formation. No material failure, no calcification inside the material, and only minor calcification extrinsic to the matrix were observed.

CONCLUSIONS

This pilot study provides evidence that bacterial cellulose may be suitable for pulmonary valve prostheses and surgical pulmonary artery plasty. Further studies on the high pressure side of the left heart are needed.

Composite of bacterial cellulose and gelatin: A versatile biocompatible scaffold for tissue engineering

Synthesis of 0.4 ± 0.03 g/L per day of pure and porous bacterial cellulose (BC) scaffolds (scaffBC) and BC scaffolds modified with gelatin (scaffBC/Gel) was carried out using the Medusomyces gisevii Sa-28 bacterial strain. FT-IR spectroscopy and X-ray diffraction analysis showed that the scaffolds largely consist of crystalline cellulose I (Iα, Iß). Heating of BC with gelatin to 60 °C with subsequent lyophilization led to its modification by adsorption and binding of low-molecular fractions of gelatin and the formation of small pores between the fibers, which increased the biocompatibility and solubility of BC. The solubility of scaffBC and scaffBC/Gel was 20.8 % and 44.4 %, respectively, which enhances degradation in vivo. Light microscopy, scanning electron microscopy, and microcomputed tomography showed a uniform distribution of pores with a diameter of 100-500 μm. The chicken chorioallantoic membrane (CAM) model and subcutaneous implantation in rats confirmed low immunogenicity and intense formation of collagen fibers in both scaffolds and active germination of new blood vessels in scaffBC and scaffBC/Gel. The proliferative cellular activity of fibroblasts confirmed the safety of scaffolds. Taken together, the results obtained show that scaffBC/Gel can be used for the engineering of hard and soft tissues, which opens opportunities for further research.

Magnetically-activated, nanostructured cellulose for efficient capture of circulating tumor cells from the blood sample of head and neck cancer patients

In this report, the relative efficiency of cellulose nanocrystals (CNCs) and nanofibers (CNFs) to capture circulating tumor cells (CTCs) from the blood sample of head and neck cancer (HNC) patients was evaluated. Detection and enumeration of CTCs are critical for monitoring cancer progression. Both types of nanostructured cellulose were chemically modified with Epithelial Cell Adhesion Molecule (EpCAM) antibody and iron oxide nanoparticles. The EpCAM antibody facilitated the engagement of CTCs, promoting entrapment within the cellulose cage structure. Iron oxide nanoparticles, on the other hand, rendered the cages activatable via the use of a magnet for the capture and separation of entrapped CTCs. The efficiency of the network structures is shown in head and neck cancer (HNC) patients' blood samples. It was observed that the degree of chemical functionalization of hydroxyl groups located within the CNCs or CNFs with anti-EpCAM determined the efficiency of the system's interaction with CTCs. Further, our result indicated that inflexible scaffolds of nanocrystals interacted more efficiently with CTCs than that of the fibrous CNF scaffolds. Network structures derived from CNCs demonstrated comparable CTC capturing efficiency to commercial standard, OncoDiscover®. The output of the work will provide the chemical design principles of cellulosic materials intended for constructing affordable platforms for monitoring cancer progression in 'real time'.

Cellulosic Textiles-An Appealing Trend for Different Pharmaceutical Applications

Cellulose, the most abundant biopolymer in nature, is derived from various sources. The production of pharmaceutical textiles based on cellulose represents a growing sector. In medicated textiles, textile and pharmaceutical sciences are integrated to develop new healthcare approaches aiming to improve patient compliance. Through the possibility of cellulose functionalization, pharmaceutical textiles can broaden the applications of cellulose in the biomedical field. This narrative review aims to illustrate both the methods of extraction and preparation of cellulose fibers, with a particular focus on nanocellulose, and diverse pharmaceutical applications like tissue restoration and antimicrobial, antiviral, and wound healing applications. Additionally, the merging between fabricated cellulosic textiles with drugs, metal nanoparticles, and plant-derived and synthetic materials are also illustrated. Moreover, new emerging technologies and the use of smart medicated textiles (3D and 4D cellulosic textiles) are not far from those within the review scope. In each section, the review outlines some of the limitations in the use of cellulose textiles, indicating scientific research that provides significant contributions to overcome them. This review also points out the faced challenges and possible solutions in a trial to present an overview on all issues related to the use of cellulose for the production of pharmaceutical textiles.

A double-crosslinked nanocellulose-reinforced dexamethasone-loaded collagen hydrogel for corneal application and sustained anti-inflammatory activity

In cases of blinding disease or trauma, hydrogels have been proposed as scaffolds for corneal regeneration and vehicles for ocular drug delivery. Restoration of corneal transparency, augmenting a thin cornea and postoperative drug delivery are particularly challenging in resource-limited regions where drug availability and patient compliance may be suboptimal. Here, we report a bioengineered hydrogel based on porcine skin collagen as an alternative to human donor corneal tissue for applications where long-term stability of the hydrogel is required. The hydrogel is reinforced with cellulose nanofibers extracted from the Ciona intestinalis sea invertebrate followed by double chemical and photochemical crosslinking. The hydrogel is additionally loaded with dexamethasone to provide sustained anti-inflammatory activity. The reinforced double-crosslinked hydrogel after drug loading maintained high optical transparency with significantly improved mechanical characteristics compared to non-reinforced hydrogels, while supporting a gradual sustained drug release for 60 days in vitro. Dexamethasone, after exposure to crosslinking and sterilization procedures used in hydrogel production, inhibited tube formation and cell migration of TNFα-stimulated vascular endothelial cells. The drug-loaded hydrogels suppressed key pro-inflammatory cytokines CCL2 and CXCL5 in TNFα-stimulated human corneal epithelial cells. Eight weeks after intra-stromal implantation in the cornea of 12 New-Zealand white rabbits subjected to an inflammatory suture stimulus, the dexamethasone-releasing hydrogels suppressed TNFα, MMP-9, and leukocyte and fibroblast cell invasion, resulting in reduced corneal haze, sustained corneal thickness and stromal morphology, and reduced overall vessel invasion. This collagen-nanocellulose double-crosslinked hydrogel can be implanted to treat corneal stromal disease while suppressing inflammation and maintaining transparency after corneal transplantation. STATEMENT OF SIGNIFICANCE: To treat blinding diseases, hydrogel scaffolds have been proposed to facilitate corneal restoration and ocular drug delivery. Here, we improve on a clinically tested collagen-based scaffold to improve mechanical robustness and enzymatic resistance by incorporating sustainably sourced nanocellulose and dual chemical-photochemical crosslinking to reinforce the scaffold, while simultaneously achieving sustained release of an incorporated anti-inflammatory drug, dexamethasone. Evaluated in the context of a corneal disease model with inflammation, the drug-releasing nanocellulose-reinforced collagen scaffold maintained the cornea's transparency and resisted degradation while suppressing inflammation postoperatively. This biomaterial could therefore potentially be applied in a wider range of sight-threatening diseases, overcoming suboptimal administration of postoperative medications to maintain hydrogel integrity and good vision.

Adipose stem cells in tissue regeneration and repair: From bench to bedside

ADSCs are a large number of mesenchymal stem cells in Adipose tissue, which can be applied to tissue engineering. ADSCs have the potential of multi-directional differentiation, and can differentiate into bone tissue, cardiac tissue, urothelial cells, skin tissue, etc. Compared with other mesenchymal stem cells, ADSCs have a multitude of promising advantages, such as abundant number, accessibility in cell culture, stable function, and less immune rejection. There are two main methods to use ADSCs for tissue repair and regeneration. One is to implant the "ADSCs-scaffold composite" into the injured site to promote tissue regeneration. The other is cell-free therapy: using ADSC-exos or ADSC-CM alone to release a large number of miRNAs, cytokines and other bioactive substances to promote tissue regeneration. The tissue regeneration potential of ADSCs is regulated by a variety of cytokines, signaling molecules, and external environment. The differentiation of ADSCs into different tissues is also induced by growth factors, ions, hormones, scaffold materials, physical stimulation, and other factors. The specific mechanisms are complex, and most of the signaling pathways need to be further explored. This article reviews and summarizes the mechanism and clinical application of ADSCs in tissue injury repair so far, and puts forward further problems that need to be solved in this field, hoping to provide directions for further research in this 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.

The emergence of hybrid cellulose nanomaterials as promising biomaterials

Cellulose nanomaterials (CNs) are promising green materials due to their unique properties as well as their environmental benefits. Among these materials, cellulose nanofibrils (CNFs) and nanocrystals (CNCs) are the most extensively researched types of CNs. While they share some fundamental properties like low density, biodegradability, biocompatibility, and low toxicity, they also possess unique differentiating characteristics such as morphology, rheology, aspect ratio, crystallinity, mechanical and optical properties. Therefore, numerous comparative studies have been conducted, and recently, various studies have reported the synergetic advantages resulting from combining CNF and CNC. In this review, we initiate by addressing the terminology used to describe combinations of these and other types of CNs, proposing "hybrid cellulose nanomaterials" (HCNs) as the standardized classifictation for these materials. Subsequently, we briefly cover aspects of properties-driven applications and the performance of CNs, from both an individual and comparative perspective. Next, we comprehensively examine the potential of HCN-based materials, highlighting their performance for various applications. In conclusion, HCNs have demonstraded remarkable success in diverse areas, such as food packaging, electronic devices, 3D printing, biomedical and other fields, resulting in materials with superior performance when compared to neat CNF or CNC. Therefore, HCNs exhibit great potential for the development of environmentally friendly materials with enhanced properties.

Bacterial Nanocellulose Hydrogel: A Promising Alternative Material for the Fabrication of Engineered Vascular Grafts

Blood vessels are crucial in the human body, providing essential nutrients to all tissues while facilitating waste removal. As the incidence of cardiovascular disease rises, the demand for efficient treatments increases concurrently. Currently, the predominant interventions for cardiovascular disease are autografts and allografts. Although effective, they present limitations including high costs and inconsistent success rates. Recently, synthetic vascular grafts, made from artificial materials, have emerged as promising alternatives to traditional methods. Among these materials, bacterial cellulose hydrogel exhibits significant potential for tissue engineering applications, particularly in developing nanoscale platforms that regulate cell behavior and promote tissue regeneration, attributed to its notable physicochemical and biocompatible properties. This study reviews recent progress in fabricating engineered vascular grafts using bacterial nanocellulose, demonstrating the efficacy of bacterial cellulose hydrogel as a biomaterial for synthetic vascular grafts, specifically for stimulating angiogenesis and neovascularization.

Fabricating a low-temperature synthesized graphene-cellulose acetate-sodium alginate scaffold for the generation of ovarian cancer spheriod and its drug assessment

3D cell culture can mimic tumor pathophysiology, which reflects cellular morphology and heterogeneity, strongly influencing gene expression, cell behavior, and intracellular signaling. It supports cell-cell and cell-matrix interaction, cell attachment, and proliferation, resulting in rapid and reliable drug screening models. We have generated an ovarian cancer spheroid in interconnected porous scaffolds. The scaffold is fabricated using low-temperature synthesized graphene, cellulose acetate, and sodium alginate. Graphene nanosheets enhance cell proliferation and aggregation, which aids in the formation of cancer spheroids. The spheroids are assessed after day 7 and 14 for the generation of reactive oxygen species (ROS), expression of the hypoxia inducing factor (HIF-1⍺) and vascular endothelial growth factor (VEGF). Production of ROS was observed due to the aggregated tumor mass, and enhanced production of HIF-1⍺ and VEGF results from a lack of oxygen and nutrition. Furthermore, the efficacy of anticancer drug doxorubicin at varying concentrations is assessed on ovarian cancer spheroids by studying the expression of caspase-3/7 at day 7 and 14. The current findings imply that the graphene-cellulose-alginate (GCA) scaffold generates a reliable ovarian cancer spheroid model to test the efficacy of the anticancer drug.

Photocross-Linkable and Shape-Memory Biomaterial Hydrogel Based on Methacrylated Cellulose Nanofibres

In the context of three-dimensional (3D) cell culture and tissue engineering, 3D printing is a powerful tool for customizing in vitro 3D cell culture models that are critical for understanding the cell-matrix and cell-cell interactions. Cellulose nanofibril (CNF) hydrogels are emerging in constructing scaffolds able to imitate tissue in a microenvironment. A direct modification of the methacryloyl (MA) group onto CNF is an appealing approach to synthesize photocross-linkable building blocks in formulating CNF-based bioinks for light-assisted 3D printing; however, it faces the challenge of the low efficiency of heterogenous surface modification. Here, a multistep approach yields CNF methacrylate (CNF-MA) with a decent degree of substitution while maintaining a highly dispersible CNF hydrogel, and CNF-MA is further formulated and copolymerized with monomeric acrylamide (AA) to form a super transparent hydrogel with tuneable mechanical strength (compression modulus, approximately 5-15 kPa). The resulting photocurable hydrogel shows good printability in direct ink writing and good cytocompatibility with HeLa and human dermal fibroblast cell lines. Moreover, the hydrogel reswells in water and expands to all directions to restore its original dimension after being air-dried, with further enhanced mechanical properties, for example, Young's modulus of a 1.1% CNF-MA/1% PAA hydrogel after reswelling in water increases to 10.3 kPa from 5.5 kPa.

Hydrothermally magnetic particles fabricated hydrocalumite based biopolymeric composites for toxic chromium removal

Hexavalent chromium is an emerging environmental pollutant that leads to various effects on living organisms. The developed clay material, hydrocalumite (HC) possesses promising chromium adsorption capacity but because of its powder form it cannot be used in column studies. Hence, it is aimed to prepared HC in an usable hybrid bio-composite form by dispersing HC in biopolymeric matrixes like chitosan (CS) and cellulose (Cel) as HCCS and HCCel bio-composites for Cr(VI) removal from water. For quick separation after adsorption, the magnetic particles sprayed HCCS (Fe3O4@HCCS) and HCCel (Fe3O4@HCCel) bio-composites were prepared which possess high adsorption capacity. Different instrumental techniques like FTIR, SEM, and EDAX studies were used to examine the synthesized magnetic bio-composites in order to determine their physicochemical properties. The promising adsorbents namely Fe3O4@HCCS and Fe3O4@HCCel bio-composites were examined for Cr(VI) removal in batch mode. The maximum chromium adsorption capacity of Fe3O4@HCCS and Fe3O4@HCCel bio-composites were found at 43.4 mg/L and 31.8 mg/L, respectively within 45 min. The Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) isotherms were used to reinterpret the equilibrium data of the synthetic magnetic bio-composites. According to the thermodynamic findings, chromium adsorption onto magnetic bio-composites is an endothermic and spontaneous reaction. The NaOH solution makes it simple to regenerate the chromium adsorbed magnetic bio-composites, which can be successfully employed upto four times. The synthesized Fe3O4@HCCS and Fe3O4@HCCel bio-composites act as efficient adsorbents for chromium removal.

Extracellular matrix component-derived nanoparticles for drug delivery and tissue engineering

The extracellular matrix (ECM) consists of a complex combination of proteins, proteoglycans, and other biomolecules. ECM-based materials have been demonstrated to have high biocompatibility and bioactivity, which may be harnessed for drug delivery and tissue engineering applications. Herein, nanoparticles incorporating ECM-based materials and their applications in drug delivery and tissue engineering are reviewed. Proteins such as gelatin, collagen, and fibrin as well as glycosaminoglycans including hyaluronic acid, chondroitin sulfate, and heparin have been employed for cancer therapeutic delivery, gene delivery, and wound healing and regenerative medicine. Strategies for modifying and functionalizing these materials with synthetic and natural polymers or to enable stimuli-responsive degradation and drug release have increased the efficacy of these materials and nano-systems. The incorporation and modification of ECM-based materials may be used to drive drug targeting and increase tissue-specific cell differentiation more effectively.

Biological Macromolecule-Based Scaffolds for Urethra Reconstruction

Urethral reconstruction strategies are limited with many associated drawbacks. In this context, the main challenge is the unavailability of a suitable tissue that can endure urine exposure. However, most of the used tissues in clinical practices are non-specialized grafts that finally fail to prevent urine leakage. Tissue engineering has offered novel solutions to address this dilemma. In this technology, scaffolding biomaterials characteristics are of prime importance. Biological macromolecules are naturally derived polymers that have been extensively studied for various tissue engineering applications. This review discusses the recent advances, applications, and challenges of biological macromolecule-based scaffolds in urethral reconstruction.

Exploring nanofibrous networks with x-ray photon correlation spectroscopy through a digital twin

We demonstrate a framework of interpreting data from x-ray photon correlation spectroscopy experiments with the aid of numerical simulations to describe nanoscale dynamics in soft matter. This is exemplified with the transport of passive tracer gold nanoparticles in networks of charge-stabilized cellulose nanofibers. The main structure of dynamic modes in reciprocal space could be replicated with a simulated system of confined Brownian motion, a digital twin, allowing for a direct measurement of important effective material properties describing the local environment of the tracers.

Super-Elastic Carbonized Mushroom Aerogel for Management of Uncontrolled Hemorrhage

Uncontrolled hemorrhage is still the most common cause of potentially preventable death after trauma in prehospital settings. However, there rarely are hemostatic materials that can achieve safely and efficiently rapid hemostasis simultaneously. Here, new carbonized cellulose-based aerogel hemostatic material is developed for the management of noncompressible torso hemorrhage, the most intractable issue of uncontrolled hemorrhage. The carbonized cellulose aerogel is derived from the Agaricus bisporus after a series of processing, including cutting, carbonization, purification, and freeze-drying. In vitro, the carbonized cellulose aerogels with porous structure show improved hydrophilicity, good blood absorption, and coagulation ability, rapid shape recoverable ability under wet conditions. And in vivo, the carbonized aerogels show effective hemostatic ability in both small and big animal serious hemorrhage models. The amount of blood loss and the hemostatic time of carbonized aerogels are all better than the positive control group. Moreover, the mechanism studies reveal that the good hemostatic ability of the carbonized cellulose aerogel is associated with high hemoglobin binding efficiency, red blood cell absorption, and platelets absorption and activation. Together, the carbonized aerogel developed in this study could be promising for the management of uncontrolled hemorrhage.

Cassava microfiber-reinforced gelatin scaffold holds promise for tissue engineering by exhibiting cytocompatibility with HEK 293 cells

Cellulose fiber-reinforced composite scaffolds have recently become an interesting target for biomedical and tissue engineering (TE) applications. Cassava bagasse, a fibrous solid residue obtained after the extraction of cassava starch and soluble sugars, has been explored as a potential source of cellulose and has been successfully used to enhance the mechanical properties of gelatin scaffolds for TE purposes. This study assessed the cytocompatibility of the cassava microfiber-gelatin composite scaffold using human embryonic kidney cells (HEK 293) and a breast cancer cell line (MDA MB 231) under ISO 10993-5 standards. The viability of cells within the composite scaffold was analyzed through MTT assay. The growth of HEK 293, as well as the cell morphology, was not affected by the presence of cellulose within the composite, whereas the growth of breast cancer cells appeared to be inhibited with noticeable changes in cell morphology. These findings suggest that the presence of the cassava fiber in gelatin is not cytotoxic to HEK 293 cells. Thus, the composite is suitable for TE purposes when using normal cells. On the contrary, the presence of the fiber in gelatin elicited a cytotoxic effect in MDA MB 231 cells. Thus, the composite may not be considered for three-dimensional (3D) tumor cell studies requiring cancer cell growth. However, further studies are required to explore the use of the fiber from cassava bagasse for its anticancer cell properties, as observed in this study.

Bacterial Cellulose-Based Materials: A Perspective on Cardiovascular Tissue Engineering Applications

Today, a wide variety of bio- and nanomaterials have been deployed for cardiovascular tissue engineering (TE), including polymers, metal oxides, graphene/its derivatives, organometallic complexes/composites based on inorganic-organic components, among others. Despite several advantages of these materials with unique mechanical, biological, and electrical properties, some challenges still remain pertaining to their biocompatibility, cytocompatibility, and possible risk factors (e.g., teratogenicity or carcinogenicity), restricting their future clinical applications. Natural polysaccharide- and protein-based (nano)structures with the benefits of biocompatibility, sustainability, biodegradability, and versatility have been exploited in the field of cardiovascular TE focusing on targeted drug delivery, vascular grafts, engineered cardiac muscle, etc. The usage of these natural biomaterials and their residues offers several advantages in terms of environmental aspects such as alleviating emission of greenhouse gases as well as the production of energy as a biomass consumption output. In TE, the development of biodegradable and biocompatible scaffolds with potentially three-dimensional structures, high porosity, and suitable cellular attachment/adhesion still needs to be comprehensively studied. In this context, bacterial cellulose (BC) with high purity, porosity, crystallinity, unique mechanical properties, biocompatibility, high water retention, and excellent elasticity can be considered as promising candidate for cardiovascular TE. However, several challenges/limitations regarding the absence of antimicrobial factors and degradability along with the low yield of production and extensive cultivation times (in large-scale production) still need to be resolved using suitable hybridization/modification strategies and optimization of conditions. The biocompatibility and bioactivity of BC-based materials along with their thermal, mechanical, and chemical stability are crucial aspects in designing TE scaffolds. Herein, cardiovascular TE applications of BC-based materials are deliberated, with a focus on the most recent advancements, important challenges, and future perspectives. Other biomaterials with cardiovascular TE applications and important roles of green nanotechnology in this field of science are covered to better compare and comprehensively review the subject. The application of BC-based materials and the collective roles of such biomaterials in the assembly of sustainable and natural-based scaffolds for cardiovascular TE are discussed.

In vitro modeling of hepatocellular carcinoma niche on decellularized tomato thorny leaves: a novel natural three-dimensional (3D) scaffold for liver cancer therapeutics

Liver cancer is now one of the main causes leading to death worldwide. To achieve reliable therapeutic effects, it is crucial to develop efficient approaches to test novel anticancer drugs. Considering the significant contribution of tumor microenvironment to cell's response to medications, in vitro 3D bioinspiration of cancer cell niches can be regarded as an advanced strategy to improve the accuracy and reliability of the drug-based treatment. In this regard, decellularized plant tissues can perform as suitable 3D scaffolds for mammalian cell culture to create a near-to-real condition to test drug efficacy. Here, we developed a novel 3D natural scaffold made from decellularized tomato hairy leaves (hereafter called as DTL) to mimic the microenvironment of human hepatocellular carcinoma (HCC) for pharmaceutical purposes. The surface hydrophilicity, mechanical properties, and topography measurement and molecular analyses revealed that the 3D DTL scaffold is an ideal candidate for liver cancer modeling. The cells exhibited a higher growth and proliferation rate within the DTL scaffold, as verified by quantifying the expression of related genes, DAPI staining, and SEM imaging of the cells. Moreover, prilocaine, an anticancer drug, showed a higher effectiveness against the cancer cells cultured on the 3D DTL scaffold, compared to a 2D platform. Taken together, this new cellulosic 3D scaffold can be confidently proposed for chemotherapeutic testing of drugs on hepatocellular carcinoma.

Wet-spinnability and crosslinked Fiber properties of alginate/hydroxyethyl cellulose with varied proportion for potential use in tendon tissue engineering

Researchers have examined different bio-inspired materials in tissue engineering and regenerative medicine to fabricate scaffolds to address tendon regeneration requirements. We developed fibers based on alginate (Alg) and hydroxyethyl cellulose (HEC) by wet-spinning technique to mimic the fibrous sheath of ECM. Various proportions (25:75, 50:50, 75:25) of 1 % Alg and 4 % HEC were blended to this aim. Two steps of crosslinking with different concentrations of CaCl₂ (2.5 and 5 %) and glutaraldehyde (2.5 %) were used to improve physical and mechanical properties. The fibers were characterized by FTIR, SEM, swelling, degradation, and tensile tests. The in vitro proliferation, viability, and migration of tenocytes on the fibers were also evaluated. Moreover, the biocompatibility of implanted fibers was investigated in an animal model. The results showed ionic and covalent molecular interactions between the components. In addition, by properly maintaining surface morphology, fiber alignment, and swelling, lower concentrations of HEC in the blending provided good degradability and mechanical features. The mechanical strength of fibers was in the range of collagenous fibers. Increasing the crosslinking led to significantly different mechanical behaviors in terms of tensile strength and elongation at break. Because of good in vitro and in vivo biocompatibility, tenocyte proliferation, and migration, the biological macromolecular fibers could serve as desirable tendon substitutes. This study provides more practical insight into tendon tissue engineering in translational medicine.

Mimicking natural electrical environment with cellulose acetate scaffolds enhances collagen formation of osteoblasts

The medical field is continuously seeking new solutions and materials, where cellulose materials due to their high biocompatibility have great potential. Here we investigate the applicability of cellulose acetate (CA) electrospun fibers for bone tissue regeneration. For the first time we show the piezoelectric properties of electrospun CA fibers via high voltage switching spectroscopy piezoresponse force microscopy (HVSS-PFM) tests, which are followed by surface potential studies using Kelvin probe force microscopy (KPFM) and zeta potential measurements. Piezoelectric coefficient for CA fibers of 6.68 ± 1.70 pmV^-1 along with high surface (718 mV) and zeta (-12.2 mV) potentials allowed us to mimic natural electrical environment favoring bone cell attachment and growth. Importantly, the synergy between increased surface potential and highly developed structure of the fibrous scaffold led to the formation of a vast 3D network of collagen produced by osteoblasts only after 7 days of in vitro culture. We clearly show the advantages of CA scaffolds as a bone replacement material, when long-lasting structural support is needed.

Scaffold Using Chitosan, Agarose, Cellulose, Dextran and Protein for Tissue Engineering-A Review

Biological macromolecules like polysaccharides/proteins/glycoproteins have been widely used in the field of tissue engineering due to their ability to mimic the extracellular matrix of tissue. In addition to this, these macromolecules are found to have higher biocompatibility and no/lesser toxicity when compared to synthetic polymers. In recent years, scaffolds made up of proteins, polysaccharides, or glycoproteins have been highly used due to their tensile strength, biodegradability, and flexibility. This review is about the fabrication methods and applications of scaffolds made using various biological macromolecules, including polysaccharides like chitosan, agarose, cellulose, and dextran and proteins like soy proteins, zein proteins, etc. Biopolymer-based nanocomposite production and its application and limitations are also discussed in this review. This review also emphasizes the importance of using natural polymers rather than synthetic ones for developing scaffolds, as natural polymers have unique properties, like high biocompatibility, biodegradability, accessibility, stability, absence of toxicity, and low cost.

Alginate-Based Biomaterials in Tissue Engineering and Regenerative Medicine

Today, with the salient advancements of modern and smart technologies related to tissue engineering and regenerative medicine (TE-RM), the use of sustainable and biodegradable materials with biocompatibility and cost-effective advantages have been investigated more than before. Alginate as a naturally occurring anionic polymer can be obtained from brown seaweed to develop a wide variety of composites for TE, drug delivery, wound healing, and cancer therapy. This sustainable and renewable biomaterial displays several fascinating properties such as high biocompatibility, low toxicity, cost-effectiveness, and mild gelation by inserting divalent cations (e.g., Ca2+). In this context, challenges still exist in relation to the low solubility and high viscosity of high-molecular weight alginate, high density of intra- and inter-molecular hydrogen bonding, polyelectrolyte nature of the aqueous solution, and a lack of suitable organic solvents. Herein, TE-RM applications of alginate-based materials are deliberated, focusing on current trends, important challenges, and future prospects.

Biological Materials Processing: Time-Tested Tricks for Sustainable Fiber Fabrication

There is an urgent need to improve the sustainability of the materials we produce and use. Here, we explore what humans can learn from nature about how to sustainably fabricate polymeric fibers with excellent material properties by reviewing the physical and chemical aspects of materials processing distilled from diverse model systems, including spider silk, mussel byssus, velvet worm slime, hagfish slime, and mistletoe viscin. We identify common and divergent strategies, highlighting the potential for bioinspired design and technology transfer. Despite the diversity of the biopolymeric fibers surveyed, we identify several common strategies across multiple systems, including: (1) use of stimuli-responsive biomolecular building blocks, (2) use of concentrated fluid precursor phases (e.g., coacervates and liquid crystals) stored under controlled chemical conditions, and (3) use of chemical (pH, salt concentration, redox chemistry) and physical (mechanical shear, extensional flow) stimuli to trigger the transition from fluid precursor to solid material. Importantly, because these materials largely form and function outside of the body of the organisms, these principles can more easily be transferred for bioinspired design in synthetic systems. We end the review by discussing ongoing efforts and challenges to mimic biological model systems, with a particular focus on artificial spider silks and mussel-inspired materials.

Cellulose and Lignin-Derived Scaffold and Their Biological Application in Tissue Engineering, Drug Delivery, and Wound Healing: A Review

The goal of tissue engineering is to repair and regenerate diseased and damaged tissues and organs with functional and biocompatible materials that mimic native and original tissues which leads to maintaining and improvement of tissue function. Lignin and cellulose are the most abundant polymers in nature and have many applications in industry. Moreover, recently the physicochemical behaviors of lignin and cellulose, including biocompatibility, biodegradability, and mechanical properties, have been used in diverse biological applications ranging from drug delivery to tissue engineering. To assess these aims, this review gives an overview and comprehensive knowledge and highlights the origin and applications of lignin and cellulose-derived scaffolds in different tissue engineering and other biological applications. Finally, the challenges for future development using lignin and cellulose are also included. Plant-based tissue engineering is a promising technology for progressing areas in biomedicine, regenerative medicine, and nanomedicine, with much research focused on the development of newer material scaffolds with individual specific features to make functional and biocompatible tissues and organs for medical applications.

Drug/bioactive eluting chitosan composite foams for osteochondral tissue engineering

Joint defects associated with a variety of etiologies often extend deep into the subchondral bone leading to functional impairment and joint immobility, and it is a very challenging task to regenerate the bone-cartilage interface offering significant opportunities for biomaterial-based interventions to improve the quality of life of patients. Herein drug-/bioactive-loaded porous tissue scaffolds incorporating nano-hydroxyapatite (nHAp), chitosan (CS) and either hydroxypropyl methylcellulose (HPMC) or Bombyx mori silk fibroin (SF) are fabricated through freeze drying method as subchondral bone substitute. A combination of spectroscopy and microscopy (Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), and X-ray fluorescence (XRF) were used to analyze the structure of the porous biomaterials. The compressive mechanical properties of these scaffolds are biomimetic of cancellous bone tissues and capable of releasing drugs/bioactives (exemplified with triamcinolone acetonide, TA, or transforming growth factor-β1, TGF-β1, respectively) over a period of days. Mouse preosteoblast MC3T3-E1 cells were observed to adhere and proliferate on the tissue scaffolds as confirmed by the cell attachment, live-dead assay and alamarBlue™ assay. Interestingly, RT-qPCR analysis showed that the TA downregulated inflammatory biomarkers and upregulated the bone-specific biomarkers, suggesting such tissue scaffolds have long-term potential for clinical application.

Electrospun Nanomaterials Based on Cellulose and Its Derivatives for Cell Cultures: Recent Developments and Challenges

The development of electrospun nanofibers based on cellulose and its derivatives is an inalienable task of modern materials science branches related to biomedical engineering. The considerable compatibility with multiple cell lines and capability to form unaligned nanofibrous frameworks help reproduce the properties of natural extracellular matrix and ensure scaffold applications as cell carriers promoting substantial cell adhesion, growth, and proliferation. In this paper, we are focusing on the structural features of cellulose itself and electrospun cellulosic fibers, including fiber diameter, spacing, and alignment responsible for facilitated cell capture. The study emphasizes the role of the most frequently discussed cellulose derivatives (cellulose acetate, carboxymethylcellulose, hydroxypropyl cellulose, etc.) and composites in scaffolding and cell culturing. The key issues of the electrospinning technique in scaffold design and insufficient micromechanics assessment are discussed. Based on recent studies aiming at the fabrication of artificial 2D and 3D nanofiber matrices, the current research provides the applicability assessment of the scaffolds toward osteoblasts (hFOB line), fibroblastic (NIH/3T3, HDF, HFF-1, L929 lines), endothelial (HUVEC line), and several other cell types. Furthermore, a critical aspect of cell adhesion through the adsorption of proteins on the surfaces is touched upon.

Biomimetic Bilayered Scaffolds for Tissue Engineering: From Current Design Strategies to Medical Applications

Tissue damage due to cancer, congenital anomalies, and injuries needs new efficient treatments that allow tissue regeneration. In this context, tissue engineering shows a great potential to restore the native architecture and function of damaged tissues, by combining cells with specific scaffolds. Scaffolds made of natural and/or synthetic polymers and sometimes ceramics play a key role in guiding cell growth and formation of the new tissues. Monolayered scaffolds, which consist of uniform material structure, are reported as not being sufficient to mimic complex biological environment of the tissues. Osteochondral, cutaneous, vascular, and many other tissues all have multilayered structures, therefore multilayered scaffolds seem more advantageous to regenerate these tissues. In this review, recent advances in bilayered scaffolds design applied to regeneration of vascular, bone, cartilage, skin, periodontal, urinary bladder, and tracheal tissues are focused on. After a short introduction on tissue anatomy, composition and fabrication techniques of bilayered scaffolds are explained. Then, experimental results obtained in vitro and in vivo are described, and their limitations are given. Finally, difficulties in scaling up production of bilayer scaffolds and reaching the stage of clinical studies are discussed when multiple scaffold components are used.

Ionic Liquids as Tools to Incorporate Pharmaceutical Ingredients into Biopolymer-Based Drug Delivery Systems

This mini-review focuses on the various roles that ionic liquids (ILs) play in the development and applications of biopolymer-based drug delivery systems (DDSs). Biopolymers are particularly attractive as drug delivery matrices due to their biocompatibility, low immunogenicity, biodegradability, and strength, whereas ILs can assist the formation of drug delivery systems. In this work, we showcase the different strategies that were explored using ILs in biopolymer-based DDSs, including impregnation of active pharmaceutical ingredients (APIs)-ILs into biopolymeric materials, employment of the ILs to simplify the process of making the biopolymer-based DDSs, and using the ILs either as dopants or as anchoring agents.

Porphyrin Photosensitizers Grafted in Cellulose Supports: A Review

Cellulose is the most abundant natural biopolymer and owing to its compatibility with biological tissues, it is considered a versatile starting material for developing new and sustainable materials from renewable resources. With the advent of drug-resistance among pathogenic microorganisms, recent strategies have focused on the development of novel treatment options and alternative antimicrobial therapies, such as antimicrobial photodynamic therapy (aPDT). This approach encompasses the combination of photoactive dyes and harmless visible light, in the presence of dioxygen, to produce reactive oxygen species that can selectively kill microorganisms. Photosensitizers for aPDT can be adsorbed, entrapped, or linked to cellulose-like supports, providing an increase in the surface area, with improved mechanical strength, barrier, and antimicrobial properties, paving the way to new applications, such as wound disinfection, sterilization of medical materials and surfaces in different contexts (industrial, household and hospital), or prevention of microbial contamination in packaged food. This review will report the development of porphyrinic photosensitizers supported on cellulose/cellulose derivative materials to achieve effective photoinactivation. A brief overview of the efficiency of cellulose based photoactive dyes for cancer, using photodynamic therapy (PDT), will be also discussed. Particular attention will be devoted to the synthetic routes behind the preparation of the photosensitizer-cellulose functional materials.

Hydrogels from TEMPO-Oxidized Nanofibrillated Cellulose Support In Vitro Cultivation of Encapsulated Human Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are the most prominent type of adult stem cells for clinical applications. Three-dimensional (3D) cultivation of MSCs in biomimetic hydrogels provides a more physiologically relevant cultivation microenvironment for in vitro testing and modeling, thus overcoming the limitations of traditional planar cultivation methods. Cellulose nanofibers are an excellent candidate biomaterial for synthesis of hydrogels for this application, due to their biocompatibility, tunable properties, availability, and low cost. Herein, we demonstrate the capacity of hydrogels prepared from 2,2,6,6-tetramethylpiperidine-1-oxyl -oxidized and subsequently individualized cellulose-nanofibrils to support physiologically relevant 3D in vitro cultivation of human MSCs at low solid contents (0.2-0.5 wt %). Our results show that MSCs can spread, proliferate, and migrate inside the cellulose hydrogels, while the metabolic activity and proliferative capacity of the cells as well as their morphological characteristics benefit more in the lower bulk cellulose concentration hydrogels.

The Fabrication of Gelatin-Elastin-Nanocellulose Composite Bioscaffold as a Potential Acellular Skin Substitute

Gelatin usage in scaffold fabrication is limited due to its lack of enzymatic and thermal resistance, as well as its mechanical weakness. Hence, gelatin requires crosslinking and reinforcement with other materials. This study aimed to fabricate and characterise composite scaffolds composed of gelatin, elastin, and cellulose nanocrystals (CNC) and crosslinked with genipin. The scaffolds were fabricated using the freeze-drying method. The composite scaffolds were composed of different concentrations of CNC, whereas scaffolds made of pure gelatin and a gelatin-elastin mixture served as controls. The physicochemical and mechanical properties of the scaffolds, and their cellular biocompatibility with human dermal fibroblasts (HDF), were evaluated. The composite scaffolds demonstrated higher porosity and swelling capacity and improved enzymatic resistance compared to the controls. Although the group with 0.5% (w/v) CNC recorded the highest pore size homogeneity, the diameters of most of the pores in the composite scaffolds ranged from 100 to 200 μm, which is sufficient for cell migration. Tensile strength analysis revealed that increasing the CNC concentration reduced the scaffolds' stiffness. Chemical analyses revealed that despite chemical and structural alterations, both elastin and CNC were integrated into the gelatin scaffold. HDF cultured on the scaffolds expressed collagen type I and α-SMA proteins, indicating the scaffolds' biocompatibility with HDF. Overall, the addition of elastin and CNC improved the properties of gelatin-based scaffolds. The composite scaffolds are promising candidates for an acellular skin substitute.

Cellulose-Based Scaffolds: A Comparative Study for Potential Application in Articular Cartilage

Osteoarthritis is a highly prevalent disease worldwide that leads to cartilage loss. Tissue engineering, involving scaffolds, cells, and stimuli, has shown to be a promising strategy for its repair. Thus, this study aims to manufacture and characterise different scaffolds with poly(ε-caprolactone) (PCL) with commercial cellulose (microcrystalline (McC) and methyl cellulose (MC) or cellulose from agro-industrial residues (corncob (CcC)) and at different percentages, 1%, 2%, and 3%. PCL scaffolds were used as a control. Morphologically, the produced scaffolds presented porosities within the desired for cell incorporation (57% to 65%). When submitted to mechanical tests, the incorporation of cellulose affects the compression resistance of the majority of scaffolds. Regarding tensile strength, McC2% showed the highest values. It was proven that all manufactured scaffolds suffered degradation after 7 days of testing because of enzymatic reactions. This degradation may be due to the dissolution of PCL in the organic solvent. Biological tests revealed that PCL, CcC1%, and McC3% are the best materials to combine with human dental pulp stem/stromal cells. Overall, results suggest that cellulose incorporation in PCL scaffolds promotes cellular adhesion/proliferation. Methyl cellulose scaffolds demonstrated some advantageous compressive properties (closer to native cartilaginous tissue) to proceed to further studies for application in cartilage repair.

Cellulose-based composite scaffolds for bone tissue engineering and localized drug delivery

Natural bone constitutes a complex and organized structure of organic and inorganic components with limited ability to regenerate and restore injured tissues, especially in large bone defects. To improve the reconstruction of the damaged bones, tissue engineering has been introduced as a promising alternative approach to the conventional therapeutic methods including surgical interventions using allograft and autograft implants. Bioengineered composite scaffolds consisting of multifunctional biomaterials in combination with the cells and bioactive therapeutic agents have great promise for bone repair and regeneration. Cellulose and its derivatives are renewable and biodegradable natural polymers that have shown promising potential in bone tissue engineering applications. Cellulose-based scaffolds possess numerous advantages attributed to their excellent properties of non-toxicity, biocompatibility, biodegradability, availability through renewable resources, and the low cost of preparation and processing. Furthermore, cellulose and its derivatives have been extensively used for delivering growth factors and antibiotics directly to the site of the impaired bone tissue to promote tissue repair. This review focuses on the various classifications of cellulose-based composite scaffolds utilized in localized bone drug delivery systems and bone regeneration, including cellulose-organic composites, cellulose-inorganic composites, cellulose-organic/inorganic composites. We will also highlight the physicochemical, mechanical, and biological properties of the different cellulose-based scaffolds for bone tissue engineering applications.

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Cellulose and its derivatives are renewable and biodegradable natural polymers that with great potential for bone tissue engineering.

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Cellulose-based materials can be used various therapeutics directly to the bone to achieve bone regeneration.

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Bioinks made of cellulose-based materials hold great promise to develop patient specific solutions for bone repair using 3D printing.

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Challenges associated with inaccuracies in existing preclinical models, sterilization regulatory barriers still need to be addressed before clinical translation.

Natural Biopolymers as Smart Coating Materials of Mesoporous Silica Nanoparticles for Drug Delivery

In recent years, the functionalization of mesoporous silica nanoparticles (MSNs) with different types of responsive pore gatekeepers have shown great potential for the formulation of drug delivery systems (DDS) with minimal premature leakage and site-specific controlled release. New nanotechnological approaches have been developed with the objective of utilizing natural biopolymers as smart materials in drug delivery applications. Natural biopolymers are sensitive to various physicochemical and biological stimuli and are endowed with intrinsic biodegradability, biocompatibility, and low immunogenicity. Their use as biocompatible smart coatings has extensively been investigated in the last few years. This review summarizes the MSNs coating procedures with natural polysaccharides and protein-based biopolymers, focusing on their application as responsive materials to endogenous stimuli. Biopolymer-coated MSNs, which conjugate the nanocarrier features of mesoporous silica with the biocompatibility and controlled delivery provided by natural coatings, have shown promising therapeutic outcomes and the potential to emerge as valuable candidates for the selective treatment of various diseases.

Current Status of Polysaccharides-Based Drug Delivery Systems for Nervous Tissue Injuries Repair

Neurological disorders affecting both CNS and PNS still represent one of the most critical and challenging pathologies, therefore many researchers have been focusing on this field in recent decades. Spinal cord injury (SCI) and peripheral nerve injury (PNI) are severely disabling diseases leading to dramatic and, in most cases, irreversible sensory, motor, and autonomic impairments. The challenging pathophysiologic consequences involved in SCI and PNI are demanding the development of more effective therapeutic strategies since, as yet, a therapeutic strategy that can effectively lead to a complete recovery from such pathologies is not available. Drug delivery systems (DDSs) based on polysaccharides have been receiving more and more attention for a wide range of applications, due to their outstanding physical-chemical properties. This review aims at providing an overview of the most studied polysaccharides used for the development of DDSs intended for the repair and regeneration of a damaged nervous system, with particular attention to spinal cord and peripheral nerve injury treatments. In particular, DDSs based on chitosan and their association with alginate, dextran, agarose, cellulose, and gellan were thoroughly revised.