Chitosan nanocomposite for tissue engineering and regenerative medicine: A review

Effect of nanocomposite chitosan/hydroxyapatite pH-induced hydrogels on the osteogenic differentiation of spheroids from adipose stem cells

Chitosan is gaining scientific recognition as a hydrogel in bone tissue engineering (BTE) due to its ability to support osteoblast attachment and proliferation. However, its low mechanical strength and lack of structural integrity limit its application. Nanometric hydroxyapatite (HA) is used as a filler to enhance the mechanical properties and osteoinductivity of hydrogels. In this study, chitosan-based hydrogels were systematically compared by adding 10 %, 20 %, and 30 % HA to evaluate their impact on chemical-physical properties and cellular behavior. Mechanical reinforcement of HA was evaluated by rheological and mechanical tests, with results showing a marked increase in stiffness and mechanical strength as HA concentration increased. Specifically, the Young's modulus and the compression strength increased from 26.8 kPa for chitosan alone to 63.8 kPa and with values reaching 183 kPa for the 30 wt% HA sample. Swelling tests revealed a decrease in water absorption with higher HA concentrations, while weight loss measurements showed that the addition of HA improved hydrogel stability. Biological analysis demonstrated that stem cells maintained viability, with osteopontin expression observed after 14 days of culture, indicating successful differentiation toward osteoblasts. This study highlights the significant potential of HA-enhanced chitosan hydrogels for BTE applications, with improved mechanical properties and osteoinductive capabilities.

Enhancement of stability and activity of zinc carbonate nanoparticles using chitosan, hydroxyethyl cellulose, methyl cellulose and hyaluronic acid for multifaceted applications in medicine

Currently, biopolymer-based Zn-containing nanoforms are of great interest for medical applications. However, there is lack information on optimal synthesis parameters, reagents and stabilizing agent for production of zinc carbonate nanoparticles (ZnC-NPs). In this work, synthesis of ZnC-NPs was carried out by chemical precipitation with the use of chitosan, hydroxyethyl cellulose, methyl cellulose and hyaluronic acid as stabilizing agents. The optimal precursor (Zn(CH3COO)2) and the optimal precipitator ((NH₄)₂CO₃) were detected. ZnC-NPs had one phase (Zn5(OH)6(CO3)2) with diameter from 35 to 120 nm. Thus, the optimal synthesis parameters were set as stoichiometric ratio of precursor and precipitator and the maximum concentration of biopolymer. It was found that polymers are sorbed on different crystallographic planes of crystallites, which affects the morphology of Zn5(OH)6(CO3). Quantum chemical modelling revealed that all models of interaction are energetically advantageous (∆E > 9788.910 kcal/mol) and preferably occurs through OH group, which was confirmed by FTIR spectroscopy of synthesized samples. Notably, CAM assay and histological evaluation showed that ZnC-NPs stabilized with chitosan (as represent of considered biopolymers) have no toxic effect and are compatible with CAM biological environment, which open a great potential for further studies of ZnC-NPs stabilized with biopolymers for multifaceted applications in medicine.

Construction of multifunctional tracheal substitute based on silk fibroin methacryloyl and hyaluronic acid methacryloyl with decellularized cartilaginous matrix for tracheal defect repair

The regeneration and functional recovery of tracheal tissue are of paramount importance in the research of tissue-engineered trachea. Current constructs still face some limitations in simulating the complex natural microenvironment and achieving better regenerative capacity and functional recovery. To address these challenges, the application of hydrogels with three-dimensional (3D) network structure and extracellular matrix derived from decellularized tissues and cells has become a more promising strategy. This study aims to introduce a novel bilayer multifunctional tissue-engineered tracheal substitute. Firstly, the mesh polycaprolactone (PCL) scaffold was printed by 3D printing technology, and the concentration of Silk Fibroin Methacryloyl (SilMA) hydrogel suitable for cell adhesion and proliferation and the concentration of Hyaluronic Acid Methacryloyl (HAMA) hydrogel suitable for 3D culture of chondrocytes were selected. Subsequently, the decellularized cartilaginous matrix (DCM) solution was obtained and the concentration that promotes chondrocyte proliferation and migration was screened. Finally, the multifunctional tracheal substitute, which features a HAMA-DCM composite hydrogel loaded with autologous chondrocytes as the basic framework to simulate the outer cartilaginous layer, and a 3D-printed PCL mesh scaffold coated with SilMA hydrogel loaded with autologous epithelial cells serves as internal support to simulate the inner airway epithelial layer, was prepared. Whether it was for repairing window-shape defect for 8 w or conducting long-segment in situ transplantation for 12 w, it achieved satisfactory surgical outcomes, including epithelial crawling, cartilage regeneration, and vascular remodeling.

Recent Advances in Polysaccharide-Based Hydrogels for Tumor Immunotherapy

Immunotherapy has revolutionized cancer treatment and led to a significant increase in patient survival rates and quality of life. However, the effectiveness of current immunotherapies is limited by various factors, including immune evasion mechanisms and serious side effects. Hydrogels are a type of medical material with an ideal biocompatibility, variable structure, flexible synthesis method, and physical properties. Hydrogels have long been recognized and used as a superior choice for various biomedical applications. The fascinating results were derived from both in vitro and in vivo models. The rapid expansion of this area suggests that the principles and uses of functionalized polysaccharides are transformative, motivating researchers to investigate novel polysaccharide-based hydrogels for wider applications. Polysaccharide hydrogels have proven to be a practicable delivery strategy for tumor immunotherapy due to their biocompatibility, biodegradability, and pronounced bioactive characteristics. This study aims to examine in detail the latest developments of polysaccharide hydrogels in tumor immunotherapy, focusing on their design, mechanism of action, and potential therapeutic applications.

Electrospun Chitosan/Polylactic Acid Nanofibers with Silver Nanoparticles: Structure, Antibacterial, and Cytotoxic Properties

Electrospinning, a technique for creating fabric materials from polymer solutions, is widely used in various fields, including biomedicine. The unique properties of electrospun fibrous membranes, such as large surface area, compositional versatility, and customizable porous structure, make them ideal for advanced biomedical applications like tissue engineering and wound healing. By considering the high biocompatibility and well-known regenerative potential of polylactic acid (PLA) and chitosan (CH), as well as the versatile antibacterial effect of silver nanoparticles (AgNPs), this study explores the antibacterial efficacy, adhesive properties, and cytotoxicity of electrospun chitosan membranes with a unique nanofibrous structure and varying concentrations of AgNPs. Silver nanoparticles incorporated at concentrations of 25-50 μg/mL or above significantly enhanced the antibacterial effectiveness, especially against Staphylococcus aureus and Escherichia coli. Biocompatibility assessments using umbilical cord mesenchymal stem cells demonstrated the nontoxic nature of the membranes with an AgNP concentration of 12.5 μg/mL, underscoring their potential for biomedical applications. This study provides valuable insights into developing electrospun chitosan membranes as effective antimicrobial coatings for various biomedical uses, including wound healing patches and tissue engineering constructs for soft tissue replacement.

Transition from Procoagulation to Antiplatelet Effect: Application and Mechanism of Aspirin-Modified Chitosan in Small-Diameter Vascular Grafts

Chitosan is generally considered to be a procoagulant effect, which may cause adverse phenomena such as blood clotting when used in small-diameter vascular grafts. However, it also shows good biocompatibility and anti-inflammatory properties, which can facilitate vascular reconstruction. Therefore, it is significant to transition the effect of chitosan from coagulation promotion to antiplatelet while still harnessing its bioactivity. The procoagulant mechanism of chitosan is primarily attributed to the presence of protonated amino groups in the molecular chain. If the number of amino groups in chitosan is reduced, the procoagulant effect will be diminished as well. Aspirin has a strong antiplatelet function, and its molecular structure contains numerous active carboxyl groups, which can couple with the amino groups in chitosan. Aspirin-modified chitosan retains the biological activity of chitosan while also imparting an antiplatelet effect. In our study, we used a heparinized electrospun graft as the substrate and coated it with aspirin-modified chitosan to create a functional vascular graft. The blood clotting index of the graft remained above 80% after 45 min, and the platelet activation degree was only 4.03%. Additionally, the graft maintained complete patency with stable blood flow after 4 weeks of implantation and the vascular structure was largely rebuilt.

Recent progress of functional nano-chitosan in pharmaceutical and biomedical applications: An updated review

Chitosan is a deacylated derivative of chitin, which is a naturally occurring polysaccharide found in the shells of crustaceans. Chitosan's biocompatibility, physicochemical and mechanical properties qualify it as an excellent candidate for biomedical and pharmaceutical applications. Furthermore, the nanoengineering of chitosan enhances its functional and desirable properties for various applications. Additional functionalization of nano-chitosan is possible using various crosslinkers via chemical modification of hydroxyl or amino groups chitosan. This advanced functionalized nano-chitosan enables drug stability, site-specific delivery, controlled release, and sustainable pharmacodynamic properties. It is also used as a regenerative medicine for wound healing, bone and dental repair, biosensing and disease detection, tissue engineering, etc. Therefore, this review discusses the functionalization of nano-chitosan. A brief discussion is provided on the applications of nano-chitosan in the pharmaceutical industry such as drug carriers, targeted delivery, and controlled release, as well as in the biomedical industry, including wound healing, bone, and dental repair. Additionally, the disease detection using nano-chitosan has been investigated. Lastly, future perspectives and concluding remarks are presented.

Cotton cellulose nanofiber/chitosan scaffolds for skin tissue engineering and wound healing applications

Chitosan (CS) is a promising polymeric biomaterial for use in scaffolds forin vitroskin models and wound dressings, owing to its non-antigenic and antimicrobial properties. However, CS often exhibits insufficient physicochemical properties, mechanical strength, and bioactivity, limiting its efficacy in demanding applications. To address these challenges, cotton cellulose nanofibers (CNFs) represent a promising nanomaterial for enhancing CS-based scaffolds in tissue engineering. CNF offers superior stiffness, and mechanical properties that enhance cellular adhesion and proliferation, both crucial for effective tissue regeneration and healing. This study aimed to develop and characterize a scaffold combining cotton CNF and CS, focusing on its cytocompatibility with human fibroblasts and keratinocytes. The cotton CNF/CS scaffold was fabricated using the casting technique, and its physicochemical properties and cellular compatibility were assessedin vitro. The results demonstrated that incorporating cotton CNF significantly enhanced the stability of the CS matrix. The CS scaffold with 1000 μg ml-1of cotton CNF exhibited increased roughness and reduced rupture strain compared to the pure CS scaffold. The cotton CNF/CS scaffold effectively promoted the adhesion, viability, proliferation, migration, and collagen synthesis of skin cells. Notably, increased cell viability was observed in human fibroblasts cultured on scaffolds with higher concentrations of cotton CNF (100 and 1000 μg ml-1). Based on the findings, the cotton CNF/CS scaffold demonstrates enhanced physicochemical properties and bioactivity, making it a promising candidate for the development ofin vitrohuman skin models and wound healing dressings.

Hydrophilic Components as Key Active Ingredients in Adipose-Derived Matrix Bioscaffolds for Inducing Fat Regeneration

Decellularized adipose-derived matrix (DAM) has emerged as a promising biomaterial for soft tissue reconstruction. However, due to a lack of research on its complex composition, the understanding of the key components in DAM remains limited, leading to inconsistent adipogenic properties and challenges in optimizing preparation methods purposefully. In this study, it is proposed for the first time that DAM comprises two distinct components: hydrophilic (H-DAM) and lipophilic (L-DAM), each with markedly different effects on fat regeneration. It is confirmed that H-DAM is the key component for inducing fat regeneration due to its enhanced cell-cell and cell-scaffold interactions, primarily mediated by the Hedgehog signaling pathway. In contrast, L-DAM exhibits poor cell adhesion and contains more antigenic components, leading to a higher immunoinflammatory response and reduced adipogenesis. In addition, it is found that intracellular proteins, which are more abundant in H-DAM, can be retained as beneficial components due to their hydrophilicity, contrary to the conventional view that they shall be removed. Accordingly, a purified bioscaffold with unprecedented efficacy is proposed for fat regeneration and reduced immunogenicity. This finding provides insights for developing scaffolds for fat regeneration and promotes the realization of xenotransplantation.

Fabrication of chitin-fibrin hydrogels to construct the 3D artificial extracellular matrix scaffold for vascular regeneration and cardiac tissue engineering

As the cornerstone of tissue engineering and regeneration medicine research, developing a cost-effective and bionic extracellular matrix (ECM) that can precisely modulate cellular behavior and form functional tissue remains challenging. An artificial ECM combining polysaccharides and fibrillar proteins to mimic the structure and composition of natural ECM provides a promising solution for cardiac tissue regeneration. In this study, we developed a bionic hydrogel scaffold by combining a quaternized β-chitin derivative (QC) and fibrin-matrigel (FM) in different ratios to mimic a natural ECM. We evaluated the stiffness of those composite hydrogels with different mixing ratios and their effects on the growth of human umbilical vein endothelial cells (HUVECs). The optimal hydrogels, QCFM1 hydrogels were further applied to load HUVECs into nude mice for in vivo angiogenesis. Besides, we encapsulated human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) into QCFM hydrogels and employed 3D bioprinting to achieve batch fabrication of human-engineered heart tissue (hEHT). Finally, the myocardial structure and electrophysiological function of hEHT were evaluated by immunofluorescence and optical mapping. Designed artificial ECM has a tunable modulus (220-1380 Pa), which determines the different cellular behavior of HUVECs when encapsulated in these. QCFM1 composite hydrogels with optimal stiffness (800 Pa) and porous architecture were finally identified, which could adapt for in vitro cell spreading and in vivo angiogenesis of HUVECs. Moreover, QCFM1 hydrogels were applied in 3D bioprinting successfully to achieve batch fabrication of both ring-shaped and patch-shaped hEHT. These QCFM1 hydrogels-based hEHTs possess organized sarcomeres and advanced function characteristics comparable to reported hEHTs. The chitin-derived hydrogels are first used for cardiac tissue engineering and achieve the batch fabrication of functionalized artificial myocardium. Specifically, these novel QCFM1 hydrogels provided a reliable and economical choice serving as ideal ECM for application in tissue engineering and regeneration medicine.

Culturing 3D chitosan/gelatin/nano-hydroxyapatite and bone-derived scaffolds in a dynamic environment enhances osteochondral reconstruction

Bioreactor can provide a dynamic culture environment for the in vitro construction of osteochondral tissue engineering. They facilitate more efficient exchange of nutrients and provide mechanical and other beneficial stimulation. Previous findings demonstrated that rotary flask (RF) bioreactor, rotary cell culture system (RCCS), or electromagnetic field (EMF) mediated scaffold culture could create a favorable dynamic environment for osteochondral tissue engineering. However, it is still unclear whether there is an optimal bioreactor or if bioreactors under multi-parameter coupling conditions are conducive to osteochondral tissue engineering. Based on this, the application of static T-flask (TF), RF, RCCS, and coupling environment of RCCS and EMF for osteochondral tissue engineering were systematically compared. The results showed that the RCCS/EMF culture system achieved the highest level of cellular proliferation and directed differentiation. Compared with the static culture group, the expression levels of chondrogenic factors of Sox9, Col II, and ACAN and osteogenic factors of Runx2, OCN, and Col I in RCCS/EMF culture system were 2.90 ± 0.10, 3.53 ± 0.05, 3.15 ± 0.08, 7.16 ± 0.15, 5.01 ± 0.21 and 3.99 ± 0.17 folds, respectively. The 'Active osteochondral' constructs (The construct is composed of chitosan/gelatin/nano-hydroxyapatite and bone-derived scaffolds) were prepared under different culture modes in vitro and implanted into the femoral condylar defect of New Zealand rabbits. After 12 weeks, all culture modes could effectively promote the repair of osteochondral defects, in which the RCCS/EMF intervention had the best effect on the in vivo in-situ repair of osteochondral tissues. Furthermore, the fabricated cartilage and subchondral bone in the RCCS/EMF treatment group were most similar to the surrounding natural tissues, providing a new therapeutic idea for osteochondral tissue engineering.

Advances in chitosan-based blends as potential drug delivery systems: A review

During the last decades, the ever-increasing incidence of diseases has led to high rates of mortality throughout the world. On the other hand, the inability and deficiencies of conventional approaches (such as chemotherapy) in the suppression of diseases remain challenging issues. As a result, there is a fundamental requirement to develop novel, biocompatible, bioavailable, and practical nanomaterials to prevent the incidence and mortality of diseases. Chitosan (CS) derivatives and their blends are outstandingly employed as promising drug delivery systems for disease therapy. These biopolymers are indicated more efficient performance against diseases compared with conventional modalities. The CS blends possess improved physicochemical properties, ease of preparation, high affordability, etc. characteristics compared with other biopolymers and even pure CS which result in efficient thermal, mechanical, biochemical, and biomedical features. Also, these blends can be administrated through different routes without a long-term treatment period. Due to the mentioned properties, numerous formulations of CS blends are developed for pharmaceutical sciences to treat diseases. This review article highlights the progressions in the development of CS-based blends as potential drug delivery systems against diseases.

Antibacterial Potential and Biocompatibility of Chitosan/Polycaprolactone Nanofibrous Membranes Incorporated with Silver Nanoparticles

This study addresses the need for enhanced antimicrobial properties of electrospun membranes, either through surface modifications or the incorporation of antimicrobial agents, which are crucial for improved clinical outcomes. In this context, chitosan-a biopolymer lauded for its biocompatibility and extracellular matrix-mimicking properties-emerges as an excellent candidate for tissue regeneration. However, fabricating chitosan nanofibers via electrospinning often challenges the preservation of their structural integrity. This research innovatively develops a chitosan/polycaprolactone (CH/PCL) composite nanofibrous membrane by employing a layer-by-layer electrospinning technique, enhanced with silver nanoparticles (AgNPs) synthesized through a wet chemical process. The antibacterial efficacy, adhesive properties, and cytotoxicity of electrospun chitosan membranes were evaluated, while also analyzing their hydrophilicity and nanofibrous structure using SEM. The resulting CH/PCL-AgNPs composite membranes retain a porous framework, achieve balanced hydrophilicity, display commendable biocompatibility, and exert broad-spectrum antibacterial activity against both Gram-negative and Gram-positive bacteria, with their efficacy correlating to the AgNP concentration. Furthermore, our data suggest that the antimicrobial efficiency of these membranes is influenced by the timed release of silver ions during the incubation period. Membranes incorporated starting with AgNPs at a concentration of 50 µg/mL effectively suppressed the growth of both microorganisms during the early stages up to 8 h of incubation. These insights underscore the potential of the developed electrospun composite membranes, with their superior antibacterial qualities, to serve as innovative solutions in the field of tissue engineering.

A rapid protocol for synthesis of chitosan nanoparticles with ideal physicochemical features

In this research, an innovative protocol is introduced to address crucial deficiencies in the formulation of chitosan nanoparticles (Cs NPs). While NPs show potential in drug delivery systems (DDSs), their application in the clinic is hindered by various drawbacks, such as toxicity, high material costs, and time-consuming and challenging preparation procedures. Within polymer-based NPs, Cs is a plentiful natural substance derived from the deacetylation of chitin, which can be sourced from the shells of shrimp or crab. Cs NPs can be formulated using the ionic gelation technique, which involves the use of a negatively charged agent, such as tripolyphosphate (TPP), as a crosslinking agent. Even though Cs is a cost-effective and biocompatible material, the formulation of Cs NPs with the correct size and surface electrical charge (zeta potential) presents a persistent challenge. In this study, various techniques were employed to analyze the prepared Cs NPs. The size and surface charge of the NPs were evaluated using dynamic light scattering (DLS). Morphological analysis was conducted using field emission-scanning electron microscopy (FE-SEM). The chemical composition and formation of Cs NPs were investigated using Fourier transform infrared (FTIR). The stability analysis was confirmed through X-ray diffraction (XRD) analysis. Lastly, the biocompatibility of the NPs was assessed through cell cytotoxicity evaluation using the MTT assay. Moreover, here, 11 formulations with different parameters such as reaction pH, Cs:TPP ratio, type of Cs/TPP, and ultrasonication procedure were prepared. Formulation 11 was chosen as the optimized formulation based on its high stability of more than three months, biocompatibility, nanosize of 75.6 ± 18.24 nm, and zeta potential of +26.7 mV. To conclude, the method described here is easy and reproducible and can be used for facile preparation of Cs NPs with desirable physicochemical characteristics and engineering ideal platforms for drug delivery purposes.

Unveiling the potential of biomaterials and their synergistic fusion in tissue engineering

Inspired by nature, tissue engineering aims to employ intricate mechanisms for advanced clinical interventions, unlocking inherent biological potential and propelling medical breakthroughs. Therefore, medical, and pharmaceutical fields are growing interest in tissue and organ replacement, repair, and regeneration by this technology. Three primary mechanisms are currently used in tissue engineering: transplantation of cells (I), injection of growth factors (II) and cellular seeding in scaffolds (III). However, to develop scaffolds presenting highest potential, reinforcement with polymeric materials is growing interest. For instance, natural and synthetic polymers can be used. Regardless, chitosan and keratin are two biopolymers presenting great biocompatibility, biodegradability and non-antigenic properties for tissue engineering purposes offering restoration and revitalization. Therefore, combination of chitosan and keratin has been studied and results exhibit highly porous scaffolds providing optimal environment for tissue cultivation. This review aims to give an historical as well as current overview of tissue engineering, presenting mechanisms used and polymers involved in the field.

Emerging roles of hydrogel in promoting periodontal tissue regeneration and repairing bone defect

Periodontal disease is the most common type of oral disease. Periodontal bone defect is the clinical outcome of advanced periodontal disease, which seriously affects the quality of life of patients. Promoting periodontal tissue regeneration and repairing periodontal bone defects is the ultimate treatment goal for periodontal disease, but the means and methods are very limited. Hydrogels are a class of highly hydrophilic polymer networks, and their good biocompatibility has made them a popular research material in the field of oral medicine in recent years. This paper reviews the current mainstream types and characteristics of hydrogels, and summarizes the relevant basic research on hydrogels in promoting periodontal tissue regeneration and bone defect repair in recent years. The possible mechanisms of action and efficacy evaluation are discussed in depth, and the application prospects are also discussed.

Pharmaceutical applications of chitosan in skin regeneration: A review

Skin regeneration is the process that restores damaged tissues. When the body experiences trauma or surgical incisions, the skin and tissues on the wound surface become damaged. The body repairs this damage through complex physiological processes to restore the original structural and functional states of the affected tissues. Chitosan, a degradable natural bioactive polysaccharide, has attracted widespread attention partly owing to its excellent biocompatibility and antimicrobial properties; additionally, a modified form of this compound has been shown to promote skin regeneration. This review evaluates the recent research progress in the application of chitosan to promote skin regeneration. First, we discuss the basic principles of the extraction and preparation processes of chitosan from its source. Subsequently, we describe the functional properties of chitosan and the optimization of these properties through modification. We then focus on the existing chitosan-based biomaterials developed for clinical applications and their corresponding effects on skin regeneration, particularly in cases of diabetic and burn wounds. Finally, we explore the challenges and prospects associated with the use of chitosan in skin regeneration. Overall, this review provides a reference for related research and contributes to the further development of chitosan-based products in cutaneous skin regeneration.