Controlling branching structure formation of the salivary gland by the degree of chitosan deacetylation

Chitosan-based materials for dental implantology: A comprehensive review

Chitosan, a versatile biopolymer, has gained recognition in the discipline of dental implantology due to possessing salient properties. This comprehensive review explores the potential of chitosan in dental implants, focusing on its biocompatibility, bioactivity, and the various chitosan-based materials that have been utilized for dental implant therapy. The review also highlights the importance of surface treatment in dental implants to enhance osseointegration and inhibit bacterial biofilm formation. Additionally, the chemical structure, properties, and sources of chitosan are described, along with its different structural forms. The characteristics of chitosan particularly color, molecular weight, viscosity, and degree of deacetylation are discussed about their influence on its applications. This review provides valuable insights into the promising utilization of polymeric chitosan in enhancing the success and functionality of dental implants. This study highlights the potential applications of chitosan in oral implantology. Chitosan possesses various advantageous properties, including muco-adhesiveness, hemostatic action, biocompatibility, biodegradability, bioactivity, and antibacterial and antifungal activities, which enhance its uses in dental implantology. However, it has limited aqueous solubility at the physiological pH, which sometimes restricts its biological application, but this problem can be overcome by using modified chitosan or chitosan derivatives, which have also shown encouraging results. Recent research suggests that chitosan may act as a promising material for coating titanium-based implants, improving osteointegration together with antibacterial properties.

Salivary Gland Bioengineering

Salivary gland dysfunction affects millions globally, and tissue engineering may provide a promising therapeutic avenue. This review delves into the current state of salivary gland tissue engineering research, starting with a study of normal salivary gland development and function. It discusses the impact of fibrosis and cellular senescence on salivary gland pathologies. A diverse range of cells suitable for tissue engineering including cell lines, primary salivary gland cells, and stem cells are examined. Moreover, the paper explores various supportive biomaterials and scaffold fabrication methodologies that enhance salivary gland cell survival, differentiation, and engraftment. Innovative engineering strategies for the improvement of vascularization, innervation, and engraftment of engineered salivary gland tissue, including bioprinting, microfluidic hydrogels, mesh electronics, and nanoparticles, are also evaluated. This review underscores the promising potential of this research field for the treatment of salivary gland dysfunction and suggests directions for future exploration.

Salivary Gland Tissue Engineering Approaches: State of the Art and Future Directions

Salivary gland regeneration is important for developing treatments for radiation-induced xerostomia, Sjögren's syndrome, and other conditions that cause dry mouth. Culture conditions adopted from tissue engineering strategies have been used to recapitulate gland structure and function to study and regenerate the salivary glands. The purpose of this review is to highlight current trends in the field, with an emphasis on soluble factors that have been shown to improve secretory function in vitro. A PubMed search was conducted to identify articles published in the last 10 years and articles were evaluated to identify the most promising approaches and areas for further research. Results showed increasing use of extracellular matrix mimetics, such as Matrigel®, collagen, and a variety of functionalized polymers. Soluble factors that provide supportive cues, including fibroblast growth factors (FGFs) and neurotrophic factors, as well as chemical inhibitors of Rho-associated kinase (ROCK), epidermal growth factor receptor (EGFR), and transforming growth factor β receptor (TGFβR) have shown increases in important markers including aquaporin 5 (Aqp5); muscle, intestine, and stomach expression 1 (Mist1); and keratin (K5). However, recapitulation of tissue function at in vivo levels is still elusive. A focus on identification of soluble factors, cells, and/or matrix cues tested in combination may further increase the maintenance of salivary gland secretory function in vitro. These approaches may also be amenable for translation in vivo to support successful regeneration of dysfunctional glands.

Crosstalk between chitosan and cell signaling pathways

The field of tissue engineering (TE) experiences its most exciting time in the current decade. Recent progresses in TE have made it able to translate into clinical applications. To regenerate damaged tissues, TE uses biomaterial scaffolds to prepare a suitable backbone for tissue regeneration. It is well proven that the cell-biomaterial crosstalk impacts tremendously on cell biological activities such as differentiation, proliferation, migration, and others. Clarification of exact biological effects and mechanisms of a certain material on various cell types promises to have a profound impact on clinical applications of TE. Chitosan (CS) is one of the most commonly used biomaterials with many promising characteristics such as biocompatibility, antibacterial activity, biodegradability, and others. In this review, we discuss crosstalk between CS and various cell types to provide a roadmap for more effective applications of this polymer for future uses in tissue engineering and regenerative medicine.

Maintenance of the spheroid organization and properties of glandular progenitor cells by fabricated chitosan based biomaterials

Dysfunctional salivary gland (SG) is an unsolved clinical challenge, which is presented as xerostomia. Cell therapy is a promising treatment for restoring SG function. Salispheres are spheroid cellular organizations derived from SG stem cells. Benefitting from these cellular organizations, SG stem cells can be expanded to regenerate SG. During in vitro culture, the spontaneous reorganization of salispheres may change the features of residing SG stem cells. Therefore, it is imperative to explore ways to maintain the spheroid structure of salispheres during cell expansion in vitro. Herein, we explored biomaterial approaches using chitosan. Chitosan based biomaterials were fabricated in different forms to offer distinct interactive surfaces for cultured salispheres. The number and size of the salispheres increase in the chitosan-containing systems without increasing the incidence of spheroid cavitation. The effect of chitosan increases with high chitosan concentrations, which is optimum when chitosan is fabricated in a soluble form. The chitosan effect contributes to the regulation of the intercellular interactions and polarization within the spheroid structures. By retarding the process of salisphere cavitation, chitosan preserves the features of salivary gland progenitor cells in the cultured salispheres. The results suggest that the chitosan-containing system could effectively maintain the primitive structures and properties of salispheres during in vitro expansion, which demonstrates the potential application of salispheres for cell therapy of dysfunctional SG.

Interaction of chitin/chitosan with salivary and other epithelial cells-An overview

Chitin and its deacetylated form, chitosan, have been widely used for tissue engineering of both epithelial and mesenchymal tissues. Epithelial cells characterised by their sheet-like tight cellular arrangement and polarised nature, constitute a major component in various organs and play a variety of roles including protection, secretion and maintenance of tissue homeostasis. Regeneration of damaged epithelial tissues has been studied using biomaterials such as chitin, chitosan, hyaluronan, gelatin and alginate. Chitin and chitosan are known to promote proliferation of various embryonic and adult epithelial cells. However it is not clearly understood how this activity is achieved or what are the mechanisms involved in the chitin/chitosan driven proliferation of epithelial cells. Mechanistic understanding of influence of chitin/chitosan on epithelial cells will guide us to develop more targeted regenerative scaffold/hydrogel systems. Therefore, current review attempts to elicit a mechanistic insight into how chitin and chitosan interact with salivary, mammary, skin, nasal, lung, intestinal and bladder epithelial cells.

Data supporting regulating temporospatial dynamics of morphogen for structure formation of the lacrimal gland by chitosan biomaterials

The lacrimal gland is responsible for tear synthesis and secretion, and is derived from the epithelia of ocular surface and generated by branching morphogenesis. The dataset presented in this article is to support the research results of the effect of chitosan biomaterials on facilitating the structure formation of the lacrimal gland by regulating temporospatial dynamics of morphogen. The embryonic lacrimal gland explants were used as the standard experimental model for investigating lacrimal gland branching morphogenesis. Chitosan biomaterials promoted lacrimal gland branching with a dose-dependent effect. It helped in vivo binding of hepatocyte growth factor (HGF) related molecules in the epithelial-mesenchymal boundary of emerging epithelial branches. When mitogen-activated protein kinase (MAPK) or protein kinase B (Akt/PKB) inhibitors applied, the chitosan effects reduced. Nonetheless, the ratios of MAPK and Akt/PKB phosphorylation were still greater in the chitosan group than the control. The data demonstrated here confirm the essential role of HGF-signaling in chitosan-promoted structure formation of the lacrimal gland.

Regulating temporospatial dynamics of morphogen for structure formation of the lacrimal gland by chitosan biomaterials

The lacrimal gland is an important organ responsible for regulating tear synthesis and secretion. The major work of lacrimal gland (LG) is to lubricate the ocular surface and maintain the health of eyes. Functional deterioration of the lacrimal gland happens because of aging, diseases, or therapeutic complications, but without effective treatments till now. The LG originates from the epithelium of ocular surface and develops by branching morphogenesis. To regenerate functional LGs, it is required to explore the way of recapitulating and facilitating the organ to establish the intricate and ramified structure. In this study, we proposed an approach using chitosan biomaterials to create a biomimetic environment beneficial to the branching structure formation of developing LG. The morphogenetic effect of chitosan was specific and optimized to promote LG branching. With chitosan, increase in temporal expression and local concentration of endogenous HGF-related molecules creates an environment around the emerging tip of LG epithelia. By efficiently enhancing downstream signaling of HGF pathways, the cellular activities and behaviors were activated to contribute to LG branching morphogenesis. The morphogenetic effect of chitosan was abolished by either ligand or receptor deprivation, or inhibition of downstream signaling transduction. Our results elucidated the underlying mechanism accounting for chitosan morphogenetic effects on LG, and also proposed promising approaches with chitosan to assist tissue structure formation of the LG.

Data supporting chitosan facilitates structure formation of the salivary gland by regulating the basement membrane components

To investigate the role of basement membrane (BM) in chitosan-mediated morphogenesis of the salivary glands, the embryonic submandibular gland (SMG) experimental model was used. Chitosan promotes branching at distinct stages in SMG morphogenesis. When enzymes such as type IV collagenase, dispase, and cathepsin B were used to digest the BM components, the morphogenetic effect mediated by chitosan disappeared. Immunofluorescence revealed that the corresponding receptors for BM components, including CD49c, CD49f, CD29, and dystroglycan, were locally enriched at the epithelial-mesenchymal junction around BM areas. The functional roles of laminin α1 and α5 in SMG branching were explored via siRNA knockdown, and suppression was confirmed at both the RNA and protein levels (Yang and Hsiao, Biomaterials, http://dx.doi.org/10.1016/j.biomaterials.2015.06.028, 2015). This data article demonstrates the experimental approaches to investigate the role of basement membrane in the structure formation of the salivary gland engineered by biomaterials.

Chitosan facilitates structure formation of the salivary gland by regulating the basement membrane components

Tissue structure is important for inherent physiological function and should be recapitulated during tissue engineering for regenerative purposes. The salivary gland is a branched organ that is responsible for saliva secretion and regulation. The salivary glands develop from epithelial-mesenchymal interactions, and depend on the support of the basement membrane (BM). Chitosan-based biomaterials have been demonstrated to be competent in facilitating the formation of salivary gland tissue structure. However, the underlying mechanisms have remained elusive. In the developing submandibular gland (SMG), the chitosan effect was found to diminish when collagen and laminin were removed from cultured SMG explants. Chitosan increased the expression of BM components including collagen, laminin, and heparan sulfate proteoglycan, and also facilitated BM components and the corresponding receptors to be expressed in tissue-specific patterns beneficial for SMG branching. The chitosan effect decreased when either laminin components or receptors were inhibited, as well when the downstream signaling was blocked. Our results revealed that chitosan promotes salivary glands branching through the BM. By regulating BM components and receptors, chitosan efficiently stimulated downstream signaling to facilitate salivary gland branching. The present study revealed the underlying mechanism of the chitosan effect in engineering SMG structure formation.

Obstructor A organizes matrix assembly at the apical cell surface to promote enzymatic cuticle maturation in Drosophila

Assembly and maturation of the apical extracellular matrix (aECM) is crucial for protecting organisms, but underlying molecular mechanisms remain poorly understood. Epidermal cells secrete proteins and enzymes that assemble at the apical cell surface to provide epithelial integrity and stability during developmental growth and upon tissue damage. We analyzed molecular mechanisms of aECM assembly and identified the conserved chitin-binding protein Obst-A (Obstructor A) as an essential regulator. We show in Drosophila that Obst-A is required to coordinate protein and chitin matrix packaging at the apical cell surface during development. Secreted by epidermal cells, the Obst-A protein is specifically enriched in the apical assembly zone where matrix components are packaged into their highly ordered architecture. In obst-A null mutant larvae, the assembly zone is strongly diminished, resulting in severe disturbance of matrix scaffold organization and impaired aECM integrity. Furthermore, enzymes that support aECM stability are mislocalized. As a biological consequence, cuticle architecture, integrity, and function are disturbed in obst-A mutants, finally resulting in immediate lethality upon wounding. Our studies identify a new core organizing center, the assembly zone that controls aECM assembly at the apical cell surface. We propose a genetically conserved molecular mechanism by which Obst-A forms a matrix scaffold to coordinate trafficking and localization of proteins and enzymes in the newly deposited aECM. This mechanism is essential for maturation and stabilization of the aECM in a growing and remodeling epithelial tissue as an outermost barrier.

Biomimetic Composites Based on Calcium Phosphates and Chitosan - Hyaluronic Acid with Potential Application in Bone Tissue Engineering

Composites based on calcium phosphates (CP) and mixtures of biopolymers (chitosan and hyaluronic acid) have been prepared by a biomimetic co-precipitation method and tested as scaffolds for bone tissue engineering. The biomimetic strategy is inspired by natural mineralization processes, where the synthesized minerals are usually combined with proteins, polysaccharides or other mineral forms to form composite, in physiological conditions of temperature and pH. Fourier transformed infrared spectroscopy, scanning electron microscopy, X-ray diffraction and XPS analyses confirmed the porous morphology of the scaffolds and formation of various forms of calcium phosphates with amorphous nature. Thein vitrodegradation studies showed a slow degradation process for CP-biopolymers composites and limited swelling in simulated body fluids. The scaffolds compositions have no negative effect on osteoblasts cell, emphasizing a good biocompatibility.