Mimicked Tissue Engineering Scaffolds for Maxillofacial and Articular Cartilage Surgery

Tissue engineering is an attractive approach to induce new tissue formations at a defect site, due to disease or trauma. In many cases, tissue engineering has been proposed as the method to use in surgeries, particularly in maxillofacial and articular cartilage applications.

Tissue engineering is an attractive approach for biomedical technology. At the beginning of tissue engineering, around the 1980s, biodegradable polymers were fabricated into a “scaffold”, before being cultured with cells that regulated themselves into the proposed tissue. Then, the cultured scaffold was inserted to the body, to replace the tissue defect. From this development, tissue engineering is currently a significant issue for biomedical application. Principally, tissue engineering is applied in three main areas: (1) science, (2) medicine, and (3) engineering.

Mimicking is an attractive method that has been applied in many areas, for instance, engineering science, pharmaceutical science, and biomedical science. Mimicking is an approach that has been often been used in innovative designs and for the fabrication of biological systems. For instance, the structure and function of a cocoon provided ideas to create some general items. Generally, mimicking is classified into two main parts: (1) mimicking of structure and (2) function.

Scaffolds are important in tissue engineering as they maintain the shape of tissue during regeneration. Therefore, structural mimicking of scaffolds, similar to natural tissue, can enhance the performance of tissue formation. The extracellular matrix (ECM), which is the base component in natural tissue, is often used as the model for guidance of mimicked structure in scaffolds. ECM exhibits self-organization into different, sophisticated structures, depending on the types of tissue.

A suitable morphological and geographical structure for cell residence is an important point that requires consideration before application of polymer scaffolds in tissue engineering. One, suitable morphology for the cells is a porous structure, which has an effect on cell adhesion, proliferation, and migration. Generally, polymers are fabricated into 2D and 3D scaffolds that have suitable structures and functions for tissue engineering.

Physical and mechanical functions are an important point to consider for the mimicking of scaffolds similar to natural tissue, so mimicked physical and mechanical function, as that of natural tissue, is used in the guidance to create scaffolds. There are many different tissues in the organs of the human body, and each tissue has different physical and mechanical functions, which fit to their organs and systems. For instance, bone tissue has more mechanical strength and stiffness than skin tissue. This is because bone tissue in the skeletal system, which has to resist high mechanical force during the movement of the body. Therefore, to understand the physical and mechanical properties of each tissue is the guidance to mimic performance scaffolds. In this chapter, mimicked physical and mechanical functions of the tissues is explained, and approaches for mimicking physical and mechanical functions in scaffolds are described.

The biological function of scaffolds plays an important role in the promotion of tissue formation. Especially, biodegradation and bioactivity are important functions for cell regulation, for completion of the tissue formation. Mimicking of biodegradation and bioactivity during tissue formation is the approach to guide the cells to regulate themselves into the completed tissue formation.

For maxillofacial surgery, scaffolds are used as performance biomaterials for enhancing new tissue formation. In the view of tissue engineering, scaffolds have the main function as the structure supporting cell behaviors. On the other hand, from the view of maxillofacial surgery, scaffolds show the function as supporting material to complete the anatomy of organs which have tissue defects.

In maxillofacial surgery, there are many cases which have defects in bone including soft tissue ( Harris CM, Laughlin R. Reconstruction of hard and soft tissue maxillofacial defects.). These defects normally come from either trauma or diseases ( Atlas Oral Maxillofac Surg Clin North Am 2013;21(1):127–38.). In the case of soft tissue defects, because of physical and biological function, there is a requirement for different scaffolds from bone tissue. For instance, soft tissue shows physical function of higher elasticity and elongation than bone tissue ( Kumar RVK, Kumar Devireddy SK, Gali RS, Chaithanyaa N, Sridhar. A Clinician’s Role in the Management of Soft Tissue Injuries of the Face: A Clinical Paper. J Maxillofac Oral Surg 2013;12(1):21–29.). Furthermore, soft tissue has a faster repairing time than bone tissue (Sangkert et al. in Int J Artif Organs 43:189–202, 2020;Sybil et al. in Ann Maxillofac Surg 10:102–107, 2020;Chouhan et al. in Biomaterials 216, 2019;). Therefore, biomaterials which match these functions are required for soft tissue in surgery. Mimicking is the approach to create biomaterials that have similar functions as that of soft tissue (Haffner-Luntzer et al. in J Orthop Res 37:2491–2498, 2019; Toledano M, Toledano-Osorio M, Carrasco-Carmona A, Vallecillo C,1 Lynch CD,2, Osorio MT, Osorio R. State of the Art on Biomaterials for Soft Tissue Augmentation in the Oral Cavity. Part I: Natural Polymers-Based Biomaterials. Polymers (Basel) 2020;12(8):1850.;). Created scaffold biomaterials which have similar physical and biological function to soft tissue are normally the key for mimicking (Haffner-Luntzer et al. in J Orthop Res 37:2491–2498, 2019). For instance, elastic polymers conjugated with biological signals are fabricated into scaffolds, based on the mimicking of physical and biological function of soft tissue (Sangkert et al. in Int J Artif Organs 43:189–202, 2020). Moreover, in some cases scaffolds need an antimicrobial function for surgery ( Watcharajittanont N, Putson C, Pripatnanont P, Meesane J. Layer-by-layer electrospun membranes of polyurethane/silk fibroin based on mimicking of oral soft tissue for guided bone regeneration. Biomed Mater 2019; 14 055,011.). For example, antimicrobial drugs are added into the scaffolds during fabrication (Sharif et al. in Polym Compos 40:1564–1575, 2019). These scaffolds are places to cover over defect site before closure to avoid microbial invasion. Maxillofacial surgery which involves a soft tissue defect is demonstrated. Mimicked scaffolds for defects included soft tissue in the maxillofacial are shown. Some examples of mimicked scaffolds in the maxillofacial are also explained. Furthermore, some ideas to develop mimicked scaffolds for soft tissue in the maxillofacial are described in this chapter.

There are many patients who suffer from cartilage tissue defects, particularly due to disease and trauma. Generally, the soft tissue of cartilage is damaged from degeneration and/or accidents. In the case of damaged cartilage tissue into the bone phase, patients will have serious pain. In such a case, the damaged areas may need total replacement. In some cases, a tissue engineering scaffold is suitable as a substitute biomaterial to regenerate new tissue (Wasyłeczko et al. in Membranes (Basel) 10:348, 2020). Creating suitable scaffolds to be similar to native tissue is important to induce tissue regeneration at the defect site. For some defects, in cartilage tissue, hydrogel scaffolds are selected for use in surgery. Hence, this chapter discusses performance hydrogel scaffolds, which are created based on the mimic approach. The geometry, morphology, structure, and functionality of performance scaffolds are considered in this chapter.

Mimicked 3D scaffolds are performance biomaterials for articular cartilage surgery in both cartilages, without and with included subchondral bone tissue defect (Fig. 11.1). In early, monophasic scaffolds are mimicked for fitting to cartilage tissue. In monophasic scaffolds, a suitable geometry, morphology, and function need to be created for use in the defect site of cartilage (Izadifar et al. in J Funct Biomater 3:799–838, 2012). The scaffolds can be used with or without cell encapsulation before implantation (Jaipaew et al. in Mater Sci Eng C-Mater 64:173–182, 2016; Kim IG, Ko J, Lee HR, Do SH, Park K..Mesenchymal cells condensation-inducible mesh scaffolds for cartilage tissue engineering. Biomaterials 2016;8518–29.;). For the latter, biphasic scaffolds are mimicked for matching to cartilage and bone tissue. Normally, biphasic scaffolds have a three-dimensional (3D) porous phase for the bone part and a hydrogel part for the cartilage (Li et al. in Regen Biomater. 2:221–228, 2015;Kazunori et al. in Tissue Eng. Part B Rev. 20:468–476, 2014;). Some biphasic scaffolds are created into the 3D porous structural part affixed to the membrane. For these scaffolds, the porous structure is in contact to cartilage tissue. On the other hand, the membrane acts as the barrier to prevent cell invasion, from synovial fluid into the porous structure that leads to disturbance of tissue formation. In this chapter, mimicked 3D scaffolds are described as well as their requirements fitting to this type of surgery. Furthermore, mimicked 3D scaffolds are explained as to their structures and functions, which are similar to cartilage tissue.

For articular cartilage surgery, hydrogel and 3D scaffolds are the main materials that play the role as structures, with suitable function to enhance tissue formation, particularly in deep defects, with included bone. On the other hand, in partial defects with non-included bone, 2D scaffolds are used to assist for guidance to completed tissue formation. Mimicking is used to create 2D scaffolds, both with similar structures and functions as the microenvironment: extracellular matrix and growth factors of cartilage tissue. In this chapter, the approach of surgery with 2D scaffolds is demonstrated, and mimicked 2D scaffolds in cartilage surgery are explained. Furthermore, fabrication and modification of mimicked 2D scaffolds are described.