Customizing the Shape and Microenvironment Biochemistry of Biocompatible Macroscopic Plant-Derived Cellulose Scaffolds

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.

Polysaccharides as a promising platform for the treatment of spinal cord injury: A review

Spinal cord injury is incurable and often results in irreversible damage to motor function and autonomic sensory abilities. To enhance the effectiveness of therapeutic substances such as cells, growth factors, drugs, and nucleic acids for treating spinal cord injuries, as well as to reduce the toxic side effects of chemical reagents, polysaccharides have been gained attention due to their immunomodulatory properties and the biocompatibility and biodegradability of polysaccharide scaffolds. Polysaccharides hold potential as drug delivery systems in treating spinal cord injuries. This article aims to present an extensive evaluation of the potential applications of polysaccharide materials in scaffold construction, drug delivery, and immunomodulation over the past five years so that offering new directions and opportunities for the treatment of spinal cord injuries.

An overview to nanocellulose clinical application: Biocompatibility and opportunities in disease treatment

Recently, the demand for organ transplantation has promptly increased due to the enhanced incidence of body organ failure, the increasing efficiency of transplantation, and the improvement in post-transplant outcomes. However, due to a lack of suitable organs for transplantation to fulfill current demand, significant organ shortage problems have emerged. Developing efficient technologies in combination with tissue engineering (TE) has opened new ways of producing engineered tissue substitutes. The use of natural nanoparticles (NPs) such as nanocellulose (NC) and nano-lignin should be used as suitable candidates in TE due to their desirable properties. Many studies have used these components to form scaffolds and three-dimensional (3D) cultures of cells derived from different tissues for tissue repair. Interestingly, these natural NPs can afford scaffolds a degree of control over their characteristics, such as modifying their mechanical strength and distributing bioactive compounds in a controlled manner. These bionanomaterials are produced from various sources and are highly compatible with human-derived cells as they are derived from natural components. In this review, we discuss some new studies in this field. This review summarizes the scaffolds based on NC, counting nanocrystalline cellulose and nanofibrillated cellulose. Also, the efficient approaches that can extract cellulose with high purity and increased safety are discussed. We concentrate on the most recent research on the use of NC-based scaffolds for the restoration, enhancement, or replacement of injured organs and tissues, such as cartilage, skin, arteries, brain, and bone. Finally, we suggest the experiments and promises of NC-based TE scaffolds.

A typical method for decellularization of plants as biomaterials

Decellularization is a process by which cells are removed from tissues or organs, leaving behind the extracellular matrix (ECM) structure. This process has gained interest in the fields of tissue engineering and regenerative medicine as a way to prepare suitable scaffolds for tissue reconstruction. Although the initial efforts come with the animal tissues, this technique can also be applied to various plant tissues with simple modifications, as plant-derived biomaterials have the benefit of being biocompatible and serving as a safe, all-natural substitute for synthetic or animal originated materials. Additionally, plant-derived biomaterials may help cells grow and differentiate, creating a three-dimensional environment for tissue regeneration and repair. Here we demonstrate a general method for plant tissue decellularization, including already experienced approaches and techniques.•Exhibit the basic steps for plant decellularization, which may be applied to several other plant tissues.•The proposed approach may be optimized considering various intended uses.•Gives basic information for the determination of decellularization efficiency.

Plant Cellulose as a Substrate for 3D Neural Stem Cell Culture

Neural stem cell (NSC)-based therapies are at the forefront of regenerative medicine strategies for various neural defects and injuries such as stroke, traumatic brain injury, and spinal cord injury. For several clinical applications, NSC therapies require biocompatible scaffolds to support cell survival and to direct differentiation. Here, we investigate decellularized plant tissue as a novel scaffold for three-dimensional (3D), in vitro culture of NSCs. Plant cellulose scaffolds were shown to support the attachment and proliferation of adult rat hippocampal neural stem cells (NSCs). Further, NSCs differentiated on the cellulose scaffold had significant increases in their expression of neuron-specific beta-III tubulin and glial fibrillary acidic protein compared to 2D culture on a polystyrene plate, indicating that the scaffold may enhance the differentiation of NSCs towards astrocytic and neuronal lineages. Our findings suggest that plant-derived cellulose scaffolds have the potential to be used in neural tissue engineering and can be harnessed to direct the differentiation of NSCs.

Aligned skeletal muscle assembly on a biofunctionalized plant leaf scaffold

Decellularized plant scaffolds have drawn attention as alternative tissue culture platforms due to their wide accessibility, biocompatibility, and diversity of innate microstructures. Particularly, in this work, monocot leaves with innate uniaxial micropatterned topography were utilized to promote cell alignment and elongation. The leaf scaffold was biofunctionalized with poly(PEGMEMA-r-VDM-r-GMA) copolymer that prevented non-specific protein adsorption and was modified with cell adhesive RGD peptide to enable cell adhesion and growth in serum-free media. The biofunctionalized leaf supported the adhesion, growth, and alignment of various human cells including embryonic stem cells (hESC) derived muscle cells. The hESC-derived myogenic progenitor cells cultured on the biofunctionalized leaf scaffold adopted a parallel orientation and were elongated along the leaf topography. These cells showed significant early myogenic differentiation and muscle-like bundled myotube formation. The aligned cells formed compact myotube assemblies and showed uniaxial muscle contraction under chemical stimulation, a critical requirement for developing functional skeletal muscle tissue. Polymer-functionalized plant leaf scaffolds offer a novel human cell culture platform and have potential in human tissue engineering applications that require parallel alignment of cells. STATEMENT OF SIGNIFICANCE: Plant scaffolds are plentiful sources in nature and present a prefabricated construct to present topographical cues to cells. Their feature width is ideal for human cell alignment and elongation, especially for muscle cells. However, plant scaffolds lack proteins that support mammalian cell culture. We have developed a polymer coated leaf scaffold that enables cell adhesion and growth in serum-free media. Human muscle cells cultured on the biofunctionalized leaf, aligned along the natural parallel micro-patterned leaf topography, and formed muscle-like bundled myotube assemblies. These assemblies showed uniaxial muscular contraction, a critical requirement for developing functional skeletal muscle tissue. The biodiversity of the plant materials offers a novel human cell culture platform with potential in human tissue engineering.

Three-Dimensional Printed Cellulose for Wound Dressing Applications

Wounds are skin tissue damage due to trauma. Many factors inhibit the wound healing phase (hemostasis, inflammation, proliferation, and alteration), such as oxygenation, contamination/infection, age, effects of injury, sex hormones, stress, diabetes, obesity, drugs, alcoholism, smoking, nutrition, hemostasis, debridement, and closing time. Cellulose is the most abundant biopolymer in nature which is promising as the main matrix of wound dressings because of its good structure and mechanical stability, moisturizes the area around the wound, absorbs excess exudate, can form elastic gels with the characteristics of bio-responsiveness, biocompatibility, low toxicity, biodegradability, and structural similarity with the extracellular matrix (ECM). The addition of active ingredients as a model drug helps accelerate wound healing through antimicrobial and antioxidant mechanisms. Three-dimensional (3D) bioprinting technology can print cellulose as a bioink to produce wound dressings with complex structures mimicking ECM. The 3D printed cellulose-based wound dressings are a promising application in modern wound care. This article reviews the use of 3D printed cellulose as an ideal wound dressing and their properties, including mechanical properties, permeability aspect, absorption ability, ability to retain and provide moisture, biodegradation, antimicrobial property, and biocompatibility. The applications of 3D printed cellulose in the management of chronic wounds, burns, and painful wounds are also discussed.

An Overview of Recent Progress in Engineering Three-Dimensional Scaffolds for Cultured Meat Production

Cultured meat is a new type of green, safe, healthy, and sustainable alternative to traditional meat that will potentially alleviate the environmental impact of animal farming and reduce the requirement for animal slaughter. However, the cultured meat structures that have been prepared lack sufficient tissue alignment. To create a product that is similar in texture and taste to traditional animal meat, muscle stem cells must be organized in a way that imitates the natural structure of animal tissue. Recently, various scaffold technologies and biomaterials have been developed to support the three-dimensional (3D) cultivation and organization of muscle stem cells. Hence, we propose an overview of the latest advancements and challenges in creating three-dimensional scaffolds for the biomanufacturing of cultured meat.

A Review of the Application of Natural and Synthetic Scaffolds in Bone Regeneration

The management of bone defects is complicated by the presence of clinical conditions, such as critical-sized defects created by high-energy trauma, tumour resection, infection, and skeletal abnormalities, whereby the bone regeneration capacity is compromised. A bone scaffold is a three-dimensional structure matrix serving as a template to be implanted into the defects to promote vascularisation, growth factor recruitment, osteogenesis, osteoconduction, and mechanical support. This review aims to summarise the types and applications of natural and synthetic scaffolds currently adopted in bone tissue engineering. The merits and caveats of natural and synthetic scaffolds will be discussed. A naturally derived bone scaffold offers a microenvironment closer to in vivo conditions after decellularisation and demineralisation, exhibiting excellent bioactivity, biocompatibility, and osteogenic properties. Meanwhile, an artificially produced bone scaffold allows for scalability and consistency with minimal risk of disease transmission. The combination of different materials to form scaffolds, along with bone cell seeding, biochemical cue incorporation, and bioactive molecule functionalisation, can provide additional or improved scaffold properties, allowing for a faster bone repair rate in bone injuries. This is the direction for future research in the field of bone growth and repair.

Enhanced osteogenesis on proantocyanidin-loaded date palm endocarp cellulosic matrices: A novel sustainable approach for guided bone regeneration

Developing inexpensive, biocompatible natural scaffolds that can support the differentiation and proliferation of stem cells has been recently emphasized by the research community to faster obtain the FDA approvals for regenerative medicine. In this regard, plant-derived cellulose materials are a novel class of sustainable scaffolding materials with high potentials for bone tissue engineering (BTE). However, low bioactivity of the plant-derived cellulose scaffolds restricts cell proliferation and cell differentiation. This limitation can be addressed though surface-functionalization of cellulose scaffolds with natural antioxidant polyphenols, e.g., grape seed proanthocyanidin (PCA)-rich extract (GSPE). Despite the various merits of GSPE as a natural antioxidant, its impact on the proliferation and adhesion of osteoblast precursor cells, and on their osteogenic differentiation is an as-yet unknown issue. Here, we investigated the effects of GSPE surface functionalization on the physicochemical properties of decellularized date (Phoenix dactyliferous) fruit inner layer (endocarp) (DE) scaffold. In this regard, various physiochemical characteristics of the DE-GSPE scaffold such as hydrophilicity, surface roughness, mechanical stiffness, porosity, and swelling, and biodegradation behavior were compared with those of the DE scaffold. Additionally, the impact of the GSPE treatment of the DE scaffold on the osteogenic response of human mesenchymal stem cells (hMSCs) was thoroughly studied. For this purpose, cellular activities including cell adhesion, calcium deposition and mineralization, alkaline phosphatase (ALP) activity, and expression levels of bone-related genes were monitored. Taken together, the GSPE treatment enhanced the physicochemical and biological properties of the DE-GSPE scaffold, thereby raising its potentials as a promising candidate for guided bone regeneration.

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.

Decellularized fennel and dill leaves as possible 3D channel network in GelMA for the development of an in vitro adipose tissue model

The development of 3D scaffold-based models would represent a great step forward in cancer research, offering the possibility of predicting the potential in vivo response to targeted anticancer or anti-angiogenic therapies. As regards, 3D in vitro models require proper materials, which faithfully recapitulated extracellular matrix (ECM) properties, adequate cell lines, and an efficient vascular network. The aim of this work is to investigate the possible realization of an in vitro 3D scaffold-based model of adipose tissue, by incorporating decellularized 3D plant structures within the scaffold. In particular, in order to obtain an adipose matrix capable of mimicking the composition of the adipose tissue, methacrylated gelatin (GelMA), UV photo-crosslinkable, was selected. Decellularized fennel, wild fennel and, dill leaves have been incorporated into the GelMA hydrogel before crosslinking, to mimic a 3D channel network. All leaves showed a loss of pigmentation after the decellularization with channel dimensions ranging from 100 to 500 µm up to 3 μm, comparable with those of human microcirculation (5–10 µm). The photo-crosslinking process was not affected by the embedded plant structures in GelMA hydrogels. In fact, the weight variation test, performed on hydrogels with or without decellularized leaves showed a weight loss in the first 96 h, followed by a stability plateau up to 5 weeks. No cytotoxic effects were detected comparing the three prepared GelMA/D-leaf structures; moreover, the ability of the samples to stimulate differentiation of 3T3-L1 preadipocytes in mature adipocytes was investigated, and cells were able to grow and proliferate in the structure, colonizing the entire microenvironment and starting to differentiate. The developed GelMA hydrogels mimicked adipose tissue together with the incorporated plant structures seem to be an adequate solution to ensure an efficient vascular system for a 3D in vitro model. The obtained results showed the potentiality of the innovative proposed approach to mimic the tumoral microenvironment in 3D scaffold-based models.

Toward Plant Cyborgs: Hydrogels Incorporated onto Plant Tissues Enable Programmable Shape Control

Engineered living materials (ELMs) that incorporate living organisms and synthetic materials enable advanced functional properties. Here, we seek to create plant cyborgs by combining plants or plant tissues with stimuli-responsive polymeric materials. Plant tissues with integrated shape control may find applications in regenerative medicine, and the shape control of living plants enables another dimension of adaptability and response to environmental threats, which can be applied to next-generation precision farming. In this work, we develop chemistry to integrate stimuli-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogels with decellularized plant tissues assisted by 3D printing. We demonstrate programmable shape morphing in response to thermal cues and ultraviolet (UV) light. Specifically, by taking advantage of the extrusion-based 3D printing method, we deposit nanocomposite PNIPAM precursors onto silane-treated decellularized leaf surface with prescribed shapes and spatial control. When subjected to external stimuli, the strain mismatch generated between the swellable nanocomposite PNIPAM and nonswellable decellularized leaf enables folding and bending to occur. This strategy to integrate the plant tissues with stimuli-responsive hydrogels allows the control of leaf morphology, opening avenues for plant-based biosensors and soft actuators to enhance food security; such materials also may find applications in biomedicine as tissue-engineering scaffolds.

Cellular Aquaculture: Prospects and Challenges

Aquaculture plays an important role as one of the fastest-growing food-producing sectors in global food and nutritional security. Demand for animal protein in the form of fish has been increasing tremendously. Aquaculture faces many challenges to produce quality fish for the burgeoning world population. Cellular aquaculture can provide an alternative, climate-resilient food production system to produce quality fish. Potential applications of fish muscle cell lines in cellular aquaculture have raised the importance of developing and characterizing these cell lines. In vitro models, such as the mouse C2C12 cell line, have been extremely useful for expanding knowledge about molecular mechanisms of muscle growth and differentiation in mammals. Such studies are in an infancy stage in teleost due to the unavailability of equivalent permanent muscle cell lines, except a few fish muscle cell lines that have not yet been used for cellular aquaculture. The Prospect of cell-based aquaculture relies on the development of appropriate muscle cells, optimization of cell conditions, and mass production of cells in bioreactors. Hence, it is required to develop and characterize fish muscle cell lines along with their cryopreservation in cell line repositories and production of ideal mass cells in suitably designed bioreactors to overcome current cellular aquaculture challenges.

The latest achievements in plant cellulose-based biomaterials for tissue engineering focusing on skin repair

The present work reviews recent developments in plant cellulose-based biomaterial design and applications, properties, characterizations, and synthesis for skin tissue engineering and wound healing. Cellulose-based biomaterials are promising materials for their remarkable adaptability with three-dimensional polymeric structure. They are capable of mimicking tissue properties, which plays a key role in tissue engineering. Besides, concerns for environmental issues have motivated scientists to move toward eco-friendly materials and natural polymer-based materials for applications in the tissue engineering field these days. Therefore, cellulose as an appropriate substitute for common polymers based on crude coal, animal, and human-derived biomolecules is greatly considered for various applications in biomedical fields. Generally, natural biomaterials lack good mechanical properties for skin tissue engineering. But using modified cellulose-based biopolymers tackles these restrictions and prevents immunogenic responses. Moreover, tissue engineering is a quick promoting field focusing on the generation of novel biomaterials with modified characteristics to improve scaffold function through physical, biochemical, and chemical tailoring. Also, nanocellulose with a broad range of applications, particularly in tissue engineering, advanced wound dressing, and as a material for coupling with drugs and sensorics, has been reviewed here. Moreover, the potential cytotoxicity and immunogenicity of cellulose-based biomaterials are addressed in this review.

Three-dimensional cell culture (3DCC) improves secretion of signaling molecules of mesenchymal stem cells (MSCs)

OBJECTIVES

The secretome of mesenchymal stem cells (MSCs), also called MSC-conditioned media (MSC-CM), represents one of the promising strategies for cellular therapy and tissue repair and regeneration. MSC-CM contains growth factors and cytokines that control many cellular responses during development and regeneration. Traditional 2D cell culture (2DCC) has previously been used to generate MSC-CM while evidence has proved that the physiological and biological behaviors of cells in 2DCC are significantly different from those in 3D cell culture (3DCC). Therefore, the objective is to compare the content of MSC-CM generated from traditional 2DCC and 3DCC using a 3D scaffold.

METHODS

Adipose tissue-derived MSCs (AT-MSCs) were isolated from four donors (N = 4) and characterized according to the criteria stipulated by the International Society for Cell Therapy (ISCT). MSCs at passage 3 were grown in traditional 2DCC until 70% confluence and MSC-CM were collected at 24, 48, and 94 h. On the other hand, MSCs at passage 3 were grown on a polystyrene scaffold for 10 days to generate a 3D model of MSCs, and then MSC-CM was collected at 24, 48, and 94 h. MSC-CM from both 2DCC and 3DCC were analyzed for protein content using ELISA. Haematoxylin eosin (HE) staining and immunofluorescence (IF) were used to characterize the 3DCC of MSCs.

RESULTS

MSCs from 2DCC were fibroblast like cells, and flow cytometry showed they were positive for CD73 and CD105 while being negative for CD14, CD19, and HLA-DR. They were also able to differentiate into adipocytes, osteoblasts, and chondrocytes. HE and IF showed that MSCs formed 3D model structures on the polystyrene scaffold. MSC-CM collected from both 2DCC and 3DCC contained growth factors, e.g., platelet derived growth factor (PDGF-AB), transforming growth factor-1 (TGF-1), hepatocyte growth factor (HGF), stromal derived factor-1 (SDF-1), interleukin 1 (IL-1), and interleukin 6 (IL-6). Concentrations of biomolecules secreted by MSCs in 3DCC were significantly higher than in 2DCC.

CONCLUSION

It could be concluded that 3DCC of MSCs using a polystyrene scaffold is a novel approach to generate MSC secretome for therapeutic applications.

Scaffolding Biomaterials for 3D Cultivated Meat: Prospects and Challenges

Cultivating meat from stem cells rather than by raising animals is a promising solution to concerns about the negative externalities of meat production. For cultivated meat to fully mimic conventional meat's organoleptic and nutritional properties, innovations in scaffolding technology are required. Many scaffolding technologies are already developed for use in biomedical tissue engineering. However, cultivated meat production comes with a unique set of constraints related to the scale and cost of production as well as the necessary attributes of the final product, such as texture and food safety. This review discusses the properties of vertebrate skeletal muscle that will need to be replicated in a successful product and the current state of scaffolding innovation within the cultivated meat industry, highlighting promising scaffold materials and techniques that can be applied to cultivated meat development. Recommendations are provided for future research into scaffolds capable of supporting the growth of high-quality meat while minimizing production costs. Although the development of appropriate scaffolds for cultivated meat is challenging, it is also tractable and provides novel opportunities to customize meat properties.

Homemade bread: Repurposing an ancient technology for in vitro tissue engineering

Numerous biomaterial scaffolds have been developed which provide architectures to support the proliferation of mammalian cells. Scaffolds derived from plant components have been utilized in several tissue engineering applications, including the production of cultured meats. Bread crumb is a common ingredient employed as a texturizer and filler in existing manufacturing processes for the production of animal meat products. Though an unconventional choice as a scaffolding material, we developed a yeast-free "soda bread" with controllable porosity and mechanical properties which is stable over several weeks in culture with fibroblasts, myoblasts and pre-osteoblasts. All cells were able to proliferate throughout the three-dimensional scaffolds, depositing extra-cellular matrix while exhibiting low stress and high viability. Importantly, myoblasts were also able to differentiate into myotubes, a key step required for the culture of skeletal muscle tissue. The results suggest opportunities for the dual-use possibility of utilizing existing texturizer and filler components in future lab grown meat products, however this will of course require further validation. Regardless, the bread-derived scaffolds presented here are simply produced, inherently edible and support muscle tissue engineering, qualities which highlight their utility in the production of future meat products.

The Emerging Role of Decellularized Plant-Based Scaffolds as a New Biomaterial

The decellularization of plant-based biomaterials to generate tissue-engineered substitutes or in vitro cellular models has significantly increased in recent years. These vegetal tissues can be sourced from plant leaves and stems or fruits and vegetables, making them a low-cost, accessible, and sustainable resource from which to generate three-dimensional scaffolds. Each construct is distinct, representing a wide range of architectural and mechanical properties as well as innate vasculature networks. Based on the rapid rise in interest, this review aims to detail the current state of the art and presents the future challenges and perspectives of these unique biomaterials. First, we consider the different existing decellularization techniques, including chemical, detergent-free, enzymatic, and supercritical fluid approaches that are used to generate such scaffolds and examine how these protocols can be selected based on plant cellularity. We next examine strategies for cell seeding onto the plant-derived constructs and the importance of the different functionalization methods used to assist in cell adhesion and promote cell viability. Finally, we discuss how their structural features, such as inherent vasculature, porosity, morphology, and mechanical properties (i.e., stiffness, elasticity, etc.) position plant-based scaffolds as a unique biomaterial and drive their use for specific downstream applications. The main challenges in the field are presented throughout the discussion, and future directions are proposed to help improve the development and use of vegetal constructs in biomedical research.

Investigating the Viability of Epithelial Cells on Polymer Based Thin-Films

The development of novel polymer-based materials opens up possibilities for several novel applications, such as advanced wound dressings, bioinks for 3D biofabrication, drug delivery systems, etc. The aim of this study was to evaluate the viability of vascular and intestinal epithelial cells on different polymers as a selection procedure for more advanced cell-polymer applications. In addition, possible correlations between increased cell viability and material properties were investigated. Twelve polymers were selected, and thin films were prepared by dissolution and spin coating on silicon wafers. The prepared thin films were structurally characterized by Fourier transform infrared spectroscopy, atomic force microscopy, and goniometry. Their biocompatibility was determined using two epithelial cell lines (human umbilical vein endothelial cells and human intestinal epithelial cells), assessing the metabolic activity, cell density, and morphology. The tested cell lines showed different preferences regarding the culture substrate. No clear correlation was found between viability and individual substrate characteristics, suggesting that complex synergistic effects may play an important role in substrate design. These results show that a systematic approach is required to compare the biocompatibility of simple cell culture substrates as well as more complex applications (e.g., bioinks).

Microvascular Tissue Engineering-A Review

Tissue engineering and regenerative medicine have come a long way in recent decades, but the lack of functioning vasculature is still a major obstacle preventing the development of thicker, physiologically relevant tissue constructs. A large part of this obstacle lies in the development of the vessels on a microscale-the microvasculature-that are crucial for oxygen and nutrient delivery. In this review, we present the state of the art in the field of microvascular tissue engineering and demonstrate the challenges for future research in various sections of the field. Finally, we illustrate the potential strategies for addressing some of those challenges.

Integrating biomaterials and food biopolymers for cultured meat production

Cultured meat has recently achieved mainstream prominence due to the emergence of societal and industrial interest. In contrast to animal-based production of traditional meat, the cultured meat approach entails laboratory cultivation of engineered muscle tissue. However, bioengineers have hitherto engineered tissues to fulfil biomedical endpoints, and have had limited experience in engineering muscle tissue for its post-mortem traits, which broadly govern consumer definitions of meat quality. Furthermore, existing tissue engineering approaches face fundamental challenges in technical feasibility and industrial scalability for cultured meat production. This review discusses how animal-based meat production variables influence meat properties at both the molecular and functional level, and whether current cultured meat approaches recapitulate these properties. In addition, this review considers how conventional meat producers employ exogenous biopolymer-based meat ingredients and processing techniques to mimic desirable meat properties in meat products. Finally, current biomaterial strategies for engineering muscle and adipose tissue are surveyed in the context of emerging constraints that pertain to cultured meat production, such as edibility, sustainability and scalability, and potential areas for integrating biomaterials and food biopolymer approaches to address these constraints are discussed. STATEMENT OF SIGNIFICANCE: Laboratory-grown or cultured meat has gained increasing interest from industry and the public, but currently faces significant impediment to market feasibility. This is due to fundamental knowledge gaps in producing realistic meat tissues via conventional tissue engineering approaches, as well as translational challenges in scaling up these approaches in an efficient, sustainable and high-volume manner. By defining the molecular basis for desirable meat quality attributes, such as taste and texture, and introducing the fundamental roles of food biopolymers in mimicking these properties in conventional meat products, this review aims to bridge the historically disparate fields of meat science and biomaterials engineering in order to inspire potentially synergistic strategies that address some of these challenges.

Plant-Based Scaffolds in Tissue Engineering

A wide range of platforms has been developed for 3D culture of cells in vitro to aggregate and align cells to resemble in vivo conditions in order to enhance communication between cells and promote differentiation. The cellulose skeleton of plant tissue can serve as an attainable scaffold for mammalian cells after decellularization, which is advantageous when compared to synthetic polymers or animal-derived scaffolds. Adjustable variables to modify the physical and biochemical properties of the resulting scaffolds include the protocol for the sodium dodecyl sulfate (SDS)-based decellularization procedure, surface coatings for cell attachment, plant type for decellularization, differentiation media, and integrity and shape of the substrate. These tunable cellulose platforms can host a wide range of mammalian cell types from muscle to bone cells, as well as malignancies. Here, fundamentals and applications of decellularized plant-based scaffolds are discussed. These biocompatible, naturally perfused, tunable, and easily prepared decellularized scaffolds may allow eco-friendly manufacturing frameworks for application in tissue engineering and organs-on-a-chip.

Supercritical carbon dioxide decellularization of plant material to generate 3D biocompatible scaffolds

The use of plant-based biomaterials for tissue engineering has recently generated interest as plant decellularization produces biocompatible scaffolds which can be repopulated with human cells. The predominant approach for vegetal decellularization remains serial chemical processing. However, this technique is time-consuming and requires harsh compounds which damage the resulting scaffolds. The current study presents an alternative solution using supercritical carbon dioxide (scCO2). Protocols testing various solvents were assessed and results found that scCO2 in combination with 2% peracetic acid decellularized plant material in less than 4 h, while preserving plant microarchitecture and branching vascular network. The biophysical and biochemical cues of the scCO2 decellularized spinach leaf scaffolds were then compared to chemically generated scaffolds. Data showed that the scaffolds had a similar Young's modulus, suggesting identical stiffness, and revealed that they contained the same elements, yet displayed disparate biochemical signatures as assessed by Fourier-transform infrared spectroscopy (FTIR). Finally, human fibroblast cells seeded on the spinach leaf surface were attached and alive after 14 days, demonstrating the biocompatibility of the scCO2 decellularized scaffolds. Thus, scCO2 was found to be an efficient method for plant material decellularization, scaffold structure preservation and recellularization with human cells, while performed in less time (36 h) than the standard chemical approach (170 h).

Surface-Modified Nanocellulose for Application in Biomedical Engineering and Nanomedicine: A Review

Presently, a plenty of concerns related to the environment are due to the overuse of petroleum-based chemicals and products; the synthesis of functional materials, starting from the natural sources, is the current trend in research. The interest for nanocellulose has recently increased in a huge range of fields, from the material science to the biomedical engineering. Nanocellulose gained this leading role because of several reasons: its natural abundance on this planet, the excellent mechanical and optical features, the good biocompatibility and the attractive capability of undergoing surface chemical modifications. Nanocellulose surface tuning techniques are adopted by the high reactivity of the hydroxyl groups available; the chemical modifications are mainly performed to introduce either charged or hydrophobic moieties that include amination, esterification, oxidation, silylation, carboxymethylation, epoxidation, sulfonation, thiol- and azido-functional capability. Despite the several already published papers regarding nanocellulose, the aim of this review involves discussing the surface chemical functional capability of nanocellulose and the subsequent applications in the main areas of nanocellulose research, such as drug delivery, biosensing/bioimaging, tissue regeneration and bioprinting, according to these modifications. The final goal of this review is to provide a novel and unusual overview on this topic that is continuously under expansion for its intrinsic sophisticated properties.

Bioreactivity of decellularized animal, plant, and fungal scaffolds: perspectives for medical applications

Numerous biomedical applications imply supportive materials to improve protective, antibacterial, and regenerative abilities upon surgical interventions, oncotherapy, regenerative medicine, and others. With the increasing variability of the possible sources, the materials of natural origin are among the safest and most accessible biomedical tools. Animal, plant, and fungal tissues can further undergo decellularization to improve their biocompatibility. Decellularized scaffolds lack the most reactive cellular material, nuclear and cytoplasmic components, that predominantly trigger immune responses. At the same time, the outstanding initial three-dimensional microarchitecture, biomechanical properties, and general composition of the scaffolds are preserved. These unique features make the scaffolds perfect ready-to-use platforms for various biomedical applications, implying cell growth and functionalization. Decellularized materials can be repopulated with various cells upon request, including epithelial, endothelial, muscle and neuronal cells, and applied for structural and functional biorepair within diverse biological sites, including the skin and musculoskeletal, cardiovascular, and central nervous systems. However, the molecular and cellular mechanisms behind scaffold and host tissue interactions remain not fully understood, which significantly restricts their integration into clinical practice. In this review, we address the essential aspects of decellularization, scaffold preparation techniques, and its biochemical composition and properties, which determine the biocompatibility and immunogenicity of the materials. With the integrated evaluation of the scaffold profile in living systems, decellularized animal, plant, and fungal scaffolds have the potential to become essential instruments for safe and controllable biomedical applications.

Creation of a contractile biomaterial from a decellularized spinach leaf without ECM protein coating: An in vitro study

Myocardial infarction (MI) results in the death of cardiac tissue, decreases regional contraction, and can lead to heart failure. Tissue engineered cardiac patches containing human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) can restore contractile function. However, cells within thick patches require vasculature for blood flow. Recently, we demonstrated fibronectin coated decellularized leaves provide a suitable scaffold for hiPS-CMs. Yet, the necessity of this additional coating step is unclear. Therefore, we compared hiPS-CM behavior on decellularized leaves coated with collagen IV or fibronectin extracellular matrix (ECM) proteins to noncoated leaves for up to 21 days. Successful coating was verified by immunofluorescence. Similar numbers of hiPS-CMs adhered to coated and noncoated decellularized leaves for 21 days. At Day 14, collagen IV coated leaves contracted more than noncoated leaves (3.25 ± 0.39% vs. 1.54 ± 0.60%; p < .05). However, no differences in contraction were found between coated leaves, coated tissue culture plastic (TCP), noncoated leaves, or noncoated TCP at other time points. No significant differences were observed in hiPS-CM spreading or sarcomere lengths on leaves with or without coating. This study demonstrates that cardiac scaffolds can be created from decellularized leaves without ECM coatings. Noncoated decellularized leaf surfaces facilitate robust cell attachment for an engineered tissue patch.

Plant- vs. Bacterial-Derived Cellulose for Wound Healing: A Review

Cellulose is a naturally existing element in the plant's cell wall and in several bacteria. The unique characteristics of bacterial cellulose (BC), such as non-toxicity, biodegradability, hydrophilicity, and biocompatibility, together with the modifiable form of nanocellulose, or the integration with nanoparticles, such as nanosilver (AgNP), all for antibacterial effects, contributes to the extensive usage of BC in wound healing applications. Due to this, BC has gained much demand and attention for therapeutical usage over time, especially in the pharmaceutical industry when compared to plant cellulose (PC). This paper reviews the progress of related research based on in vitro, in vivo, and clinical trials, including the overall information concerning BC and PC production and its mechanisms in wound healing. The physicochemical differences between BC and PC have been clearly summarized in a comparison table. Meanwhile, the latest Food and Drug Administration (FDA) approved BC products in the biomedical field are thoroughly discussed with their applications. The paper concludes on the need for further investigations of BC in the future, in an attempt to make BC an essential wound dressing that has the ability to be marketable in the global marketplace.

Plant-Based Scaffolds Modify Cellular Response to Drug and Radiation Exposure Compared to Standard Cell Culture Models

Plant-based scaffolds present many advantages over a variety of biomaterials. Recent studies explored their potential to be repopulated with human cells and thus highlight a growing interest for their use in tissue engineering or for biomedical applications. However, it is still unclear if these in vitro plant-based scaffolds can modify cell phenotype or affect cellular response to external stimuli. Here, we report the characterization of the mechano-regulation of melanoma SK-MEL-28 and prostate PC3 cells seeded on decellularized spinach leaves scaffolds, compared to cells deposited on standard rigid cell culture substrate, as well as their response to drug and radiation treatment. The results showed that YAP/TAZ signaling was downregulated, cellular morphology altered and proliferation rate decreased when cells were cultured on leaf scaffold. Interestingly, cell culture on vegetal scaffold also affected cellular response to external stress. Thus, SK-MEL-28 cells phenotype is modified leading to a decrease in MITF activity and drug resistance, while PC3 cells showed altered gene expression and radiation response. These findings shed lights on the decellularization of vegetal materials to provide substrates that can be repopulated with human cells to better reproduce a soft tissue microenvironment. However, these complex scaffolds mediate changes in cell behavior and in order to exploit the capability of matching physical properties of the various plant scaffolds to diverse physiological functionalities of cells and human tissue constructs, additional studies are required to better characterize physical and biochemical cell-substrate interactions.

Plant Tissues as 3D Natural Scaffolds for Adipose, Bone and Tendon Tissue Regeneration

Decellularized tissues are a valid alternative as tissue engineering scaffolds, thanks to the three-dimensional structure that mimics native tissues to be regenerated and the biomimetic microenvironment for cells and tissues growth. Despite decellularized animal tissues have long been used, plant tissue decellularized scaffolds might overcome availability issues, high costs and ethical concerns related to the use of animal sources. The wide range of features covered by different plants offers a unique opportunity for the development of tissue-specific scaffolds, depending on the morphological, physical and mechanical peculiarities of each plant. Herein, three different plant tissues (i.e., apple, carrot, and celery) were decellularized and, according to their peculiar properties (i.e., porosity, mechanical properties), addressed to regeneration of adipose tissue, bone tissue and tendons, respectively. Decellularized apple, carrot and celery maintained their porous structure, with pores ranging from 70 to 420 μm, depending on the plant source, and were stable in PBS at 37°C up to 7 weeks. Different mechanical properties (i.e., Eapple = 4 kPa, Ecarrot = 43 kPa, Ecelery = 590 kPa) were measured and no indirect cytotoxic effects were demonstrated in vitro after plants decellularization. After coating with poly-L-lysine, apples supported 3T3-L1 preadipocytes adhesion, proliferation and adipogenic differentiation; carrots supported MC3T3-E1 pre-osteoblasts adhesion, proliferation and osteogenic differentiation; celery supported L929 cells adhesion, proliferation and guided anisotropic cells orientation. The versatile features of decellularized plant tissues and their potential for the regeneration of different tissues are proved in this work.

High-intensity ultrasound-assisted formation of cellulose nanofiber scaffold with low and high lignin content and their cytocompatibility with gingival fibroblast cells

Cellulose nanofiber (CNF) hydrogels with low lignin (8%) (LL-CNF) and high lignin (18%) (HL-CNF) content were produced at nominal powers of 240, 720 and 1200 W using high-intensity ultrasound technology (HIUS). Freeze-dried CNF hydrogels were evaluated as scaffolds for gingival fibroblast cells proliferation aiming biomedical applications. HIUS processing improved the dispersibility of the CNF and increased the water retention value by more than 5 times. The LL-CNF had a maximum fibrillation yield of 46 wt.%, whereas the HL-CNF had a maximum fibrillation yield of 40 wt.% at nominal power of ≥720 W. Regardless of the lignin content, the CNF hydrogels exhibited a typical elastic gel-like behavior with the highest elasticity of 263 Pa. After freeze-drying, the CNF aerogels had porosity ≥ 96.8%, and swelling capacity up to 42.1 g PBS/g aerogel. Moreover, the cell proliferation assay showed no differences in proliferation among the LL-CNF and HL-CNF scaffolds up to 11 days. Therefore, CNF scaffolds prepared with lignin content up to 18% present promising application in the biomedical field.

Biocompatible chemical network of α-cellulose-ESBO (epoxidized soybean oil) scaffold for tissue engineering application

Despite many desirable properties, the use of α-cellulose in biomedical applications is limited because of its poor processability. Here we demonstrate that the chemical network of α-cellulose and epoxidized soybean oil (ESBO) can be adequately processed into biocompatible, self-standing, highly-porous scaffolds for tissue engineering applications. First, α-cellulose was dissolved in N-Methylmorpholine N-oxide monohydrate (NMMO.MH) and chemically crosslinked by ESBO. Then, the porous scaffolds of α-cellulose-ESBO were fabricated by solvent exchange and freeze-drying techniques. The scaffolds were evaluated for morphology, thermal and mechanical stability, and in vitro cell attachment and cell viability. Scanning electron microscopy images and Brunauer-Emmett-Teller results suggested that porous scaffolds provide a good surface and internal structure for cell adhesion and growth. Specifically, the α-cellulose-ESBO scaffolds support the homogeneous attachment and proliferation of MG63 cells. Overall, our results suggest that α-cellulose-ESBO chemically crosslinked networks are biocompatible and demonstrate a remarkable capacity for the development of tissue engineering platforms.

In Vitro Biocompatibility of Decellularized Cultured Plant Cell-Derived Matrices

There has been a recent increase in exploring the use of decellularized plant tissue as a novel "green" material for biomedical applications. As part of this effort, we have developed a technique to decellularize cultured plant cells (tobacco BY-2 cells and rice cells) and tissue (tobacco hairy roots) that uses deoxyribonuclease I (DNase I)). As a proof of concept, all cultured plant cells and tissue were transformed to express recombinant enhanced green fluorescent protein (EGFP) to show that the proteins of interest could be retained within the matrices. Decellularization of lyophilized tobacco BY-2 cells with DNase for 30 min depleted the DNA content from 1503 ± 459 to 31 ± 5 ng/sample. The decellularization procedure resulted in approximately 36% total protein retention (154 ± 60 vs 424 ± 70 μg/sample) and 33% EGFP retention. Similar results for DNA removal and protein retention were observed with the rice cells and tobacco hairy root matrices. When exposed to decellularized BY-2 cell-derived matrices, monolayer cultures of human foreskin fibroblasts (hFFs) maintained or increased metabolic activity, which is an indicator of cell viability. Furthermore, hFFs were able to attach, spread, and proliferate when cultured with the decellularized BY-2 cell-derived matrices in an aggregate model. Overall, these studies demonstrate that cultured plant cells and tissue can be effectively decellularized with DNase I with substantial protein retention. The resulting material has a positive impact on hFF metabolic activity and could be employed to create a three-dimensional environment for cell growth. These results thus show the promise of using naturally derived cellulose matrices from cultured plant cells and tissues for biomedical applications.

Palm readings: Manicaria saccifera palm fibers are biocompatible textiles with low immunogenicity

Plant-based fibers are a potential alternative to synthetic polymer fibers that can yield enhanced biocompatibility and mechanical properties matching those properties of tissue. Given the unique morphology of the bract of the Manicaria saccifera palm, being an interwoven meshwork of fibers, we believe that these fibers with this built-in structure could prove useful as a tissue engineering scaffold material. Thus, we first investigated the fiber's in vitro biocompatibility and immunogenicity. We cultured NIH/3T3 mouse fibroblasts, human aortic smooth muscle cells, and human adipose-derived mesenchymal stem cells on the fiber mats, which all readily attached and over 21 days grew to engulf the fibers. Importantly, this was achieved without treating the plant tissue with extracellular matrix proteins or any adhesion ligands. In addition, we measured the gene expression and protein secretion of three target inflammatory cytokines (IL-1β, IL-8, and TNFα) from THP-1 human leukemia monocytes cultured in the presence of the biotextile as an in vitro immunological model. After 24 h of culture, gene expression and protein secretion were largely the same as the control, demonstrating the low immunogenicity of Manicaria saccifera fibers. We also measured the tensile mechanical properties of the fibers. Individual fibers after processing had a Young's modulus of 9.51 ± 4.38 GPa and a tensile strength of 68.62 ± 27.93 MPa. We investigated the tensile mechanical properties of the fiber mats perpendicular to the fiber axis (transverse loading), which displayed upwards of 100% strain, but with a concession in strength compared to longitudinal loading. Collectively, our in vitro assessments point toward Manicaria saccifera as a highly biocompatible biotextile, with a range of potential clinical and engineering applications.

Decellularized ECM-derived bioinks: Prospects for the future

Decellularization aims to remove cells from tissue ultrastructure while preserving the mechanical and biological properties, which makes the decellularized extracellular matrix (dECM) an appropriate scaffold for tissue engineering applications. Three-dimensional (3D) bioprinting technology as a reproducible and accurate method can print the combination of ECM and autologous cells layer by layer to fabricate patient based cell-laden structures representing the intrinsic cues of natural ECM. This review defines ECM, classifies decellularization agents and techniques, and explains different sources of ECM. Then, bioprinting techniques, bioink concept, applications of dECM bioinks, and finally the future perspectives of 3d bioprinting technology are discussed.

Cellulose Biomaterials for Tissue Engineering

In this review, we highlight the importance of nanostructure of cellulose-based biomaterials to allow cellular adhesion, the contribution of nanostructure to macroscale mechanical properties, and several key applications of these materials for fundamental scientific research and biomedical engineering. Different features on the nanoscale can have macroscale impacts on tissue function. Cellulose is a diverse material with tunable properties and is a promising platform for biomaterial development and tissue engineering. Cellulose-based biomaterials offer some important advantages over conventional synthetic materials. Here we provide an up-to-date summary of the status of the field of cellulose-based biomaterials in the context of bottom-up approaches for tissue engineering. We anticipate that cellulose-based material research will continue to expand because of the diversity and versatility of biochemical and biophysical characteristics highlighted in this review.