Chitosan as a tissue engineering scaffold

The usage of absorbable orthopedic implants has significantly increased in recent years, which has in turn sparked intensive study in the area of bone tissue engineering. The tissue engineering method used in orthopedic applications is based on the creation of three-dimensional scaffolds that hold the regenerated tissue in place and provide reinforcement. Bone tissue engineering uses a scaffold that regulates osteoblast activity and guides the creation of new bone in the desired patterns1. Several requirements must be met for a perfect scaffold material. It must be able to be manufactured in a variety of forms. To permit cell penetration, it has to have a carefully regulated porosity architecture. Additionally, the scaffolding material must promote vascularization, tissue regeneration, cell attachment, and growth. For structural integrity to be maintained throughout culture and deployment, the scaffolds' mechanical characteristics must be good, particularly during significant deformations. Additionally, the scaffolds must be osteoconductive. Due to their biocompatibility, environmental friendliness, biodegradability, and easy processability, biopolymers have attracted a lot of interest in these materials2. Polymers are biocompatible biomaterials that can be used in tissue engineering and regenerative medicine. They might be natural, artificially biodegradable, or artificially nonbiodegradable. The biodegradable polymers, both natural and synthetic, are those that are most frequently used as biomaterials because of their versatility in chemical manipulation and capacity to disintegrate into small molecular weight fragments that can be excreted or reabsorbed by the body. At the moment, polymers are often employed as biomaterials to create scaffolds for tissue engineering and medical devices3. Polymer materials that are used as biomaterials in biomedical applications are chosen based on a number of characteristics, including molecular weight, chemical composition, solubility, structure and shape, hydrophobicity/hydrophilicity, water absorption capacity, erosion mechanism, surface energy, and breakdown. Due to their distinctive qualities, such as their high surface-to-volume ratio, high surface porosity, extremely tiny pore size, capacity to mechanical characteristics, and manage biodegradation, polymer scaffolds are receiving a lot of interest. They offer several advantages in terms of biocompatibility, flexibility in biological characteristics, and surface chemistry that are crucial for applications in tissue engineering and organ replacement in regenerative medicine4. Chitosan has received a lot of attention in this area. Chitosan polymers are semi-synthetic aminopolysaccharides with a wide variety of applications in the industrial and other biomedical sectors5. They feature unique structures, multidimensional characteristics, and highly complex functionality. In addition to being manufactured from a plentiful renewable resource, they have gained interest because they are highly effective biomaterials that are employed in a variety of applications6. Chitosan is a linear copolymer of 2-amino-2-deoxy-d-glucopyranose and 2-acetamido-2-deoxy-d-glucopyranose that is -(1–4) connected. The exoskeletons of insects, crustaceans, and fungi are the natural sources of chitosan, which has been found to be biocompatible and biodegradable7,8. The development of porous scaffolds is necessary for the engineering of epithelial and soft tissues. For cell seeding, chitosan can be produced with a porous structure. The porous structure's pore spaces enable nutrition exchange, cell migration, and proliferation. In addition, angiogenesis, which is essential for ensuring the survival and functionality of the regenerated soft tissues, benefits from the adjustable porosity of chitosan scaffolds9. Chitosan scaffolds have demonstrated in-vivo biocompatibility as well as in-vitro cytocompatibility. Implanted chitosan scaffolds seldom cause chitosan-specific responses, and chitosan typically only elicits a minor foreign body reaction in vivo10,11. For vascular tissues, collagen has been cross-linked with chitosan to provide a tubular scaffold that mimics the mechanical and morphological characteristics of blood veins and increases long-term patency rates. The extracellular membrane synthesis, cell proliferation, and adhesion were all improved by this biocompatible scaffold, which also possessed the desired porosity and pliability12. Chitosan may also aid in the regeneration and restoration of damaged or burned skin. Chitosan was employed as a porogen agent in a research where the porogen agent was cross-linked with silica particles (SiO2). In a separate protocol, peritoneal adhesions brought on by wounds, ischemia, and infections were demonstrated to be prevented by a chitosan–gelatin-modified film; however, the impact was not significant in preventing adhesion brought on by foreign bodies13. Due to the benefits, it has shown in the reduction and prevention of postoperative intraperitoneal adhesions, chitosan is the subject of intensive investigation for its potential use in the repair and regeneration of the abdominal wall in ventral hernias. Researchers looked at the efficacy of employing scaffolds made of a mix of silk fibroin and chitosan to treat ventral hernias in guinea pigs14. Even though intestinal transplantation is a common medical procedure, it is still limited by the high rate of organ rejection, the scarcity of organ donors, and the size of the donor graft. To assess the biocompatibility of the substance, rabbit colonic circular smooth muscle cells were expanded on chitosan-coated plates13. Chitosan, whether utilized for wound closure or its prospective usage in creating particular tissue grafts, has enormous possible applications for soft tissue engineering. However, there is still a lot of investigation to be done on their properties and scaffold formation. Future scaffolds ought to be able to store a variety of bioactive agents and release them in a predetermined sequence. Ethical approval Ethics approval was not required for this correspondence. Consent Informed consent was not required for this correspondence. Source of funding No funding was received. Author contribution H.H.: conceptualization, data curation, writing – original draft preparation, and writing – reviewing and editing; G.B.A.: writing – reviewing and editing, visualization, and supervision; S.B. and M.M.: data curation, writing – original draft preparation, and writing – reviewing and editing; N.G.: writing – reviewing and editing, visualization, and supervision; Z.C.: data curation and writing – original draft; A.A.A.: writing – reviewing and editing, visualization, and supervision. Conflicts of interest disclosure Authors declare that they have no conflicts of interest. Research registration unique identifying number (UIN) Not applicable. Guarantor Ali Alnazza Alhamad, PhD; PhD Student in Physical Chemistry, Department of Chemistry, Faculty of Science, University of Aleppo, Aleppo, Syria. Tel: +963 945 826; https://orcid.org/0000-0001-9401-12181218.