Preparation and characterization of poly ε-caprolactone-gelatin/multi-walled carbon nanotubes electrospun scaffolds for cartilage tissue engineering applications

Magnetic carbon nanotubes modified with proteins and hydrophilic monomers: Cytocompatibility, in-vitro toxicity assays and permeation across biological interfaces

Carbon nanotubes are promising materials for biomedical applications like delivery systems and tissue scaffolds. In this paper, magnetic carbon nanotubes (M-CNTs) covered with bovine serum albumin (M-CNTs-BSA) or functionalized with hydrophilic monomers (M-CNTs-HL) were synthesized, characterized, and evaluated concerning their interaction with Caco-2 cells. There is no comparison between these two types of functionalization, and this study aimed to verify their influence on the material's interaction with the cells. Different concentrations of the nanotubes were applied to investigate cytotoxicity, cell metabolism, oxidative stress, apoptosis, and capability to cross biomimetic barriers. The materials showed cytocompatibility up to 100 μg mL-1 and a hemolysis rate below 2 %. Nanotubes' suspensions were allowed to permeate Caco-2 monolayers for up to 8 h under the effect of the magnetic field. Magnetic nanoparticles associated with the nanotubes allowed estimation of permeation through the monolayers, with values ranging from 0.50 to 7.19 and 0.27 to 9.30 × 10-3 μg (equivalent to 0.43 to 6.22 and 0.23 to 9.54 × 10-2 % of the initially estimated mass of magnetic nanoparticles) for cells exposed and non-exposed to the magnets, respectively. Together, these results support that the developed materials are promising for applications in biomedical and biotechnological fields.

Biomedical Applications of CNT-Based Fibers

Carbon nanotubes (CNTs) have been regarded as emerging materials in various applications. However, the range of biomedical applications is limited due to the aggregation and potential toxicity of powder-type CNTs. To overcome these issues, techniques to assemble them into various macroscopic structures, such as one-dimensional fibers, two-dimensional films, and three-dimensional aerogels, have been developed. Among them, carbon nanotube fiber (CNTF) is a one-dimensional aggregate of CNTs, which can be used to solve the potential toxicity problem of individual CNTs. Furthermore, since it has unique properties due to the one-dimensional nature of CNTs, CNTF has beneficial potential for biomedical applications. This review summarizes the biomedical applications using CNTF, such as the detection of biomolecules or signals for biosensors, strain sensors for wearable healthcare devices, and tissue engineering for regenerating human tissues. In addition, by considering the challenges and perspectives of CNTF for biomedical applications, the feasibility of CNTF in biomedical applications is discussed.

Hesperidin guided injured spinal cord neural regeneration with a combination of MWCNT-collagen-hyaluronic acid composite: In-vitro analysis

Restoring the lost bioelectrical signal transmission along with the appropriate microenvironment is one of the major clinical challenges in spinal cord regeneration. In the current research, we developed a polysaccharide-based protein composite Multiwalled Carbon Nanotubes (MWCNTs)/ Collagen (Col)/ Hyaluronic acid (HA) composite with Hesperidin (Hes) natural compound to investigate its combined therapeutic effect along with biocompatibility, antioxidant activity, and electrical conductivity. The multifunctional composites were characterized via FT-IR, XRD, SEM, HR-TEM, BET, C.V, and EIS techniques. The electrical conductivity and modulus of the MWCNT-Col-HA-Hes were 0.06 S/cm and 12.3 kPa, similar to the native spinal cord. The in-vitro Cytotoxicity, cell viability, antioxidant property, and cell migration ability of the prepared composites were investigated with a PC-12 cell line. In-vitro studies revealed that the multifunctional composites show higher cell viability, antioxidant, and cell migration properties than the control cells. Reduction of ROS level indicates that the Hes presence in the composite could reduce the cell stress by protecting it from oxidative damage and promoting cell migration towards the lesion site. The developed multifunctional composite can provide the antioxidant microenvironment with compatibility and mimic the native spinal cord by providing appropriate conductivity and mechanical strength for spinal cord tissue regeneration.

Effects of mechanical properties of carbon-based nanocomposites on scaffolds for tissue engineering applications: a comprehensive review

Mechanical properties, such as elasticity modulus, tensile strength, elongation, hardness, density, creep, toughness, brittleness, durability, stiffness, creep rupture, corrosion and wear, a low coefficient of thermal expansion, and fatigue limit, are some of the most important features of a biomaterial in tissue engineering applications. Furthermore, the scaffolds used in tissue engineering must exhibit mechanical and biological behaviour close to the target tissue. Thus, a variety of materials has been studied for enhancing the mechanical performance of composites. Carbon-based nanostructures, such as graphene oxide (GO), reduced graphene oxide (rGO), carbon nanotubes (CNTs), fibrous carbon nanostructures, and nanodiamonds (NDs), have shown great potential for this purpose. This is owing to their biocompatibility, high chemical and physical stability, ease of functionalization, and numerous surface functional groups with the capability to form covalent bonds and electrostatic interactions with other components in the composite, thus significantly enhancing their mechanical properties. Considering the outstanding capabilities of carbon nanostructures in enhancing the mechanical properties of biocomposites and increasing their applicability in tissue engineering and the lack of comprehensive studies on their biosafety and role in increasing the mechanical behaviour of scaffolds, a comprehensive review on carbon nanostructures is provided in this study.

Recent advances in nano-scaffolds for tissue engineering applications: Toward natural therapeutics

Among the promising methods for repairing or replacing tissue defects in the human body and the hottest research topics in medical science today are regenerative medicine and tissue engineering. On the other hand, nanotechnology has been expanded into different areas of regenerative medicine and tissue engineering due to its essential benefits in improving performance in various fields. Nanotechnology, a helpful strategy in tissue engineering, offers new solutions to unsolved problems. Especially considering the excellent physicochemical properties of nanoscale structures, their application in regenerative medicine has been gradually developed, and a lot of research has been conducted in this field. In this regard, various nanoscale structures, including nanofibers, nanosheets, nanofilms, nano-clays, hollow spheres, and different nanoparticles, have been developed to advance nanotechnology strategies with tissue repair goals. Here, we comprehensively review the application of the mentioned nanostructures in constructing nanocomposite scaffolds for regenerative medicine and tissue engineering. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Diagnostic Tools > Biosensing.

Evaluation of the effects of chitosan nanoparticles on polyhydroxy butyrate electrospun scaffolds for cartilage tissue engineering applications

In this study, we synthesized and incorporated chitosan nanoparticles (Cs) into polyhydroxy butyrate (PHB) electrospun scaffolds for cartilage tissue engineering. The Cs nanoparticles were synthesized via an ionic gel interaction between Cs powder and tripolyphosphate (TPP). The mechanical properties, hydrophilicity, and fiber diameter of the PHB scaffolds with varying concentrations of Cs nanoparticles (1-5 wt%) were evaluated. The results of these evaluations showed that the scaffold containing 1 wt% Cs nanoparticles (P1Cs) was the optimum scaffold, with increased ultimate strength from 2.6 to 5.2 MPa and elongation at break from 5.31 % to 12.6 %. Crystallinity, degradation, and cell compatibility were also evaluated. The addition of Cs nanoparticles decreased crystallinity and accelerated hydrolytic degradation. MTT assay results showed that the proliferation of chondrocytes on the scaffold containing 1 wt% Cs nanoparticles were significantly higher than that on pure PHB after 7 days of cultivation. These findings suggest that the electrospun P1Cs scaffold has promising potential as a substrate for cartilage tissue engineering applications. This combination offers a promising approach for the fabrication of biomimetic scaffolds with enhanced mechanical properties, hydrophilicity, and cell compatibility for tissue engineering applications.

PCL/Agarose 3D-printed scaffold for tissue engineering applications: fabrication, characterization, and cellular activities

Background and purpose

Biomaterials, scaffold manufacturing, and design strategies with acceptable mechanical properties are the most critical challenges facing tissue engineering.

Experimental approach

In this study, polycaprolactone (PCL) scaffolds were fabricated through a novel three-dimensional (3D) printing method. The PCL scaffolds were then coated with 2% agarose (Ag) hydrogel. The 3D-printed PCL and PCL/Ag scaffolds were characterized for their mechanical properties, porosity, hydrophilicity, and water absorption. The construction and morphology of the printed scaffolds were evaluated via Fourier-Transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The attachment and proliferation of L929 cells cultured on the scaffolds were investigated through MTT assay on the cell culture study upon the 1st, 3rd, and 7th days.

Findings/Results

The incorporation of Ag hydrogel with PCL insignificantly decreased the mechanical strength of the scaffold. The presence of Ag enhanced the hydrophilicity and water absorption of the scaffolds, which could positively influence their cell behavior compared to the PCL scaffolds. Regarding cell morphology, the cells on the PCL scaffolds had a more rounded shape and less cell spreading, representing poor cell attachment and cell-scaffold interaction due to the hydrophobic nature of PCL. Conversely, the cells on the PCL/Ag scaffolds were elongated with a spindle-shaped morphology indicating a positive cell-scaffold interaction.

Conclusion and implications

PCL/Ag scaffolds can be considered appropriate for tissue-engineering applications.

Influence of Single-Wall Carbon Nanotube Suspension on the Mechanical Properties of Polymeric Films and Electrospun Scaffolds

Carbon nanotubes (CNTs) are used in applications ranging from electrical engineering to medical device manufacturing. It is well known that the addition of nanotubes can influence the mechanical properties of various industrial materials, including plastics. Electrospinning is a popular method for fabricating nanomaterials, widely suggested for polymer scaffold manufacturing. In this study, we aimed to describe the influence of single-walled carbon nanotube (SWCNT) suspensions on polymeric poured films and electrospun scaffolds and to investigate their structural and mechanical properties obtained from various compositions. To obtain films and electrospun scaffolds of 8 mm diameter, we used poly-ε-caprolactone (PCL) and poly(cyclohexene carbonate) (PCHC) solutions containing several mass fractions of SWCNT. The samples were characterized using tensile tests, atomic force and scanning electronic microscopy (AFM and SEM). All the studied SWCNT concentrations were shown to decrease the extensibility and strength of electrospun scaffolds, so SWCNT use was considered unsuitable for this technique. The 0.01% mass fraction of SWCNT in PCL films increased the polymer strength, while fractions of 0.03% and more significantly decreased the polymer strength and extensibility compared to the undoped polymer. The PHCH polymeric films showed a similar behavior with an extremum at 0.02% concentration for strength at break.

Review on Biomedical Advances of Hybrid Nanocomposite Biopolymeric Materials

Hybrid materials are classified as one of the most highly important topics that have been of great interest to many researchers in recent decades. There are many species that can fall under this category, one of the most important of which contain biopolymeric materials as a matrix and are additionally reinforced by different types of carbon sources. Such materials are characterized by many diverse properties in a variety industrial and applied fields but especially in the field of biomedical applications. The biopolymeric materials that fall under this label are divided into natural biopolymers, which include chitosan, cellulose, and gelatin, and industrial or synthetic polymers, which include polycaprolactone, polyurethane, and conducting polymers of variable chemical structures. Furthermore, there are many types of carbon nanomaterials that are used as enhancers in the chemical synthesis of these materials as reinforcement agents, which include carbon nanotubes, graphene, and fullerene. This research investigates natural biopolymers, which can be composed of carbon materials, and the educational and medical applications that have been developed for them in recent years. These applications include tissue engineering, scaffold bones, and drug delivery systems.

3D printed-electrospun PCL/hydroxyapatite/MWCNTs scaffolds for the repair of subchondral bone

Osteochondral defect caused by trauma or osteoarthritis exhibits a major challenge in clinical treatment with limited symptomatic effects at present. The regeneration and remodeling of subchondral bone play a positive effect on cartilage regeneration and further promotes the repair of osteochondral defects. Making use of the strengths of each preparation method, the combination of 3D printing and electrospinning is a promising method for designing and constructing multi-scale scaffolds that mimic the complexity and hierarchical structure of subchondral bone at the microscale and nanoscale, respectively. In this study, the 3D printed-electrospun poly(ɛ-caprolactone)/nano-hydroxyapatites/multi-walled carbon nanotubes (PCL/nHA/MWCNTs) scaffolds were successfully constructed by the combination of electrospinning and layer-by-layer 3D printing. The resulting dual-scale scaffold consisted of a dense layer of disordered nanospun fibers and a porous microscale 3D scaffold layer to support and promote the ingrowth of subchondral bone. Herein, the biomimetic PCL/nHA/MWCNTs scaffolds enhanced cell seeding efficiency and allowed for higher cell-cell interactions that supported the adhesion, proliferation, activity, morphology and subsequently improved the osteogenic differentiation of bone marrow mesenchymal stem cells in vitro. Together, this study elucidates that the construction of 3D printed-electrospun PCL/nHA/MWCNTs scaffolds provides an alternative strategy for the regeneration of subchondral bone and lays a foundation for subsequent in vivo studies.

Electrospun halloysite nanotube loaded polyhydroxybutyrate-starch fibers for cartilage tissue engineering

Articular cartilage is a connective load-bearing tissue with a low rate of regeneration due to slow metabolism. Fabricating tissue-like structure modified based on natural features can improve healing process. Fibrous scaffolds based on the composition of hydrophobic polyhydroxybutyrate (PHB) and hydrophilic starch reinforced using halloysite nanotubes (HNTs) with appropriate physico-chemical and biological properties was produced via electrospinning technique for long-term applications like cartilage regeneration. Textural properties were analyzed through SEM imaging that showed incorporating HNTs up to 2 wt% decreased mean fiber diameter to 158 ± 48 nm with larger pore size and appropriate porosity percentage. Moreover, the tensile strength was improved up to 4.21 ± 0.31 MPa after HNTs incorporation support chondrocyte cell growth. Furthermore, incorporating HNTs induced surface hydrophilicity and in vitro degradation. The biological assays both MTT assay and cell attachment of chondrocyte cells on 2 wt% HNTs incorporated into PHB-starch fibers indicated that HNTs incorporation can support cell growth and attachment without any toxicity for biomedical applications. To conclude, the obtained results demonstrated PHB-starch/HNTs fibrous scaffold could be potential for further experimental studies for tissue engineering applications like cartilage.

Polycaprolactone-chitosan/multi-walled carbon nanotube: A highly strengthened electrospun nanocomposite scaffold for cartilage tissue engineering

Articular cartilage is an avascular connective tissue with a slow healing rate. Tissue engineering scaffolds can provide appropriate condition to stimulate the natural healing mechanism of the damaged tissue. In this study, the electrospun nanocomposite scaffolds based on polycaprolactone (PCL)-chitosan/carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs) were fabricated with different concentrations of MWCNTs including 0.5 and 1 wt%. The samples were characterized in terms of morphology, porosity, physicochemical structure, hydrophilicity, tensile strength, bioactivity, biodegradation and cell response. The scaffold containing 0.5 wt% MWCNTs presented the lowest fiber diameter (99 ± 15 nm) and the highest tensile strength (33.81 ± 6.76 MPa) (p ≤ 0.05), which were considerable for electrospun structures. The porosity percentage of the scaffolds were maintained above 80% which is appropriate for tissue engineering. As the MWCNTs increased, the water contact angle decreased due to the increase in the hydrophilic carboxyl functional groups related to the MWCNTs. MWCNTs increased the crystallinity of the scaffold, leading to a more bioactivity and stability proportional to healing rate of a natural cartilage. Chondrocytes were well cultured on the scaffold containing MWCNTs and presented more cell viability compared to the sample without MWCNTs. The PCL-chitosan/0.5wt.%MWCNTs scaffold can be considered for supplemental studies in cartilage tissue engineering applications.

Scaffolds the backbone of tissue engineering: Advancements in use of polyhydroxyalkanoates (PHA)

Our body is built to heal from inside out naturally but wide-ranging medical conditions necessitate the need for artificial assistance, and therefore, something that can assist the body to heal wounds and damaged tissues quickly and efficiently is of utmost importance. Tissue engineering technology helps to regenerate new tissue to replace the diseased or injured one. The technology uses biodegradable porous three-dimensional scaffolds for mimicking the structure and functions of the natural extracellular matrix. The material and design of scaffolds are critical areas of biomaterial research. Biomaterial-based three-dimensional structures have been the most promising material to serve as scaffolds for seeding cells, both in vivo and in vitro. One such material is polyhydroxyalkanoates (PHAs) which are thermoplastic biopolyesters that are highly suitable for this purpose due to their enhanced biocompatibility, biodegradability, thermo-processability, diverse mechanical properties, non-toxicity and natural origin. Moreover, they have tremendous possibilities of customization through biological physical and chemical modification as well as blending with other materials. They are being used for several tissue engineering applications such as bone graft substitute, cardiovascular patches, stents, for nerve repair and in implantology as valves and sutures. The present review overviews usage of a multitude of PHA-based biomaterials for a wide range of tissue engineering applications, based on their properties suitable for the specific applications.

Proliferation and differentiation study of melatonin functionalized polycaprolactone/gelatin electrospun fibrous scaffolds for nerve tissue engineering

Melatonin (MLT), a pineal neurohormone with multiple neuroprotective, is often used for peripheral nerve recovery and regenerated nerve proliferation. In this study, Polycaprolactone/Gelatin (PG) fibrous electrospun scaffolds with various percentages of MLT (0, 1, 2, and 4%wt) were fabricated for nerve cell growth, the effects of different concentrations of MLT within PG fibers (PG, PGMLT1, PGMLT2, and PGMLT4) on the proliferation and differentiation for PC12 cells were quantitatively evaluated. The microstructures and morphologies of these scaffolds were analyzed by FE-SEM and digital camera. Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), and Water Contact Angle (WCA) were used to study the composition, ratio and properties of MLT functionalized PG scaffolds. MTT and CLSM analysis showed that appropriate amount of MLT was beneficial to the proliferation of PC12 cell. MLT can also promote cell differentiation, neurite germination, the expression levels of MAP2 mRNA and protein were dramatically increased on the composite scaffolds with the increase of MLT content, moderate addition of MLT (PGMLT2, 2%) had a prominent enhancement for neurite length. This work would provide a more comprehensive reference for further researches on MLT functionalized composite scaffolds and suggest that high-performance PGMLT fibrous scaffolds could be a promising alternative for nerve repair.

Recent applications of electrical, centrifugal, and pressurised emerging technologies for fibrous structure engineering in drug delivery, regenerative medicine and theranostics

Advancements in technology and material development in recent years has led to significant breakthroughs in the remit of fiber engineering. Conventional methods such as wet spinning, melt spinning, phase separation and template synthesis have been reported to develop fibrous structures for an array of applications. However, these methods have limitations with respect to processing conditions (e.g. high processing temperatures, shear stresses) and production (e.g. non-continuous fibers). The materials that can be processed using these methods are also limited, deterring their use in practical applications. Producing fibrous structures on a nanometer scale, in sync with the advancements in nanotechnology is another challenge met by these conventional methods. In this review we aim to present a brief overview of conventional methods of fiber fabrication and focus on the emerging fiber engineering techniques namely electrospinning, centrifugal spinning and pressurised gyration. This review will discuss the fundamental principles and factors governing each fabrication method and converge on the applications of the resulting spun fibers; specifically, in the drug delivery remit and in regenerative medicine.

Poly (ε-caprolactone)-based electrospun nano-featured substrate for tissue engineering applications: a review

The restoration of normal functioning of damaged body tissues is one of the major objectives of tissue engineering. Scaffolds are generally used as artificial supports and as substrates for regenerating new tissues and should closely mimic natural extracellular matrix (ECM). The materials used for fabricating scaffolds must be biocompatible, non-cytotoxic and bioabsorbable/biodegradable. For this application, specifically biopolymers such as PLA, PGA, PTMC, PCL etc. satisfying the above criteria are promising materials. Poly(ε-caprolactone) (PCL) is one such potential candidate which can be blended with other materials forming blends, copolymers and composites with the essential physiochemical and mechanical properties as per the requirement. Nanofibrous scaffolds are fabricated by various techniques such as template synthesis, fiber drawing, phase separation, self-assembly, electrospinning etc. Among which electrospinning is the most popular and versatile technique. It is a clean, simple, tunable and viable technique for fabrication of polymer-based nanofibrous scaffolds. The design and fabrication of electrospun nanofibrous scaffolds are of intense research interest over the recent years. These scaffolds offer a unique architecture at nano-scale with desired porosity for selective movement of small molecules and form a suitable three-dimensional matrix similar to ECM. This review focuses on PCL synthesis, modifications, properties and scaffold fabrication techniques aiming at the targeted tissue engineering applications.

Investigation and comparison of new galactosylation methods on PCL/chitosan scaffolds for enhanced liver tissue engineering

In liver tissue engineering, improving the ability of the scaffold to increase the tendency of cells to grow and proliferate is very important. In this study, new methods for modifying the surface of Polycaprolactone (PCL)/Chitosan (Cs) nanofiber for use in liver tissue engineering have been proposed. Galactosylation of chitosan was performed in three ways. According to the FE-SEM, FTIR, NMR and DSC analysis, presence of galactose in uniform nanofibers confirmed and led to a decrease in crystallinity. The hydrophobicity of the scaffolds by contact angle showed that the scaffold with galactosylated after electrospinning, had the highest contact angle of 82.22 ± 2° compared to raw scaffold with 98.52 ± 4°. According to the results of degradation in PBS, the highest rate of degradation was observed in scaffolds that were galactosylated after electrospinning. By culturing HepG2 cells on and based on the results of SEM and MTT analysis, found that the presence of galactose in the scaffolds significantly increased cell growth and proliferation without any toxicity. The immersion method shows a greater ability to improve the growth of liver cells. Also, using in-situ way due to the roughness created in this method may lead to better results especially for in-vivo tests.

Tissue Engineering in Musculoskeletal Tissue: A Review of the Literature

Tissue engineering refers to the attempt to create functional human tissue from cells in a laboratory. This is a field that uses living cells, biocompatible materials, suitable biochemical and physical factors, and their combinations to create tissue-like structures. To date, no tissue engineered skeletal muscle implants have been developed for clinical use, but they may represent a valid alternative for the treatment of volumetric muscle loss in the near future. Herein, we reviewed the literature and showed different techniques to produce synthetic tissues with the same architectural, structural and functional properties as native tissues.

Chondroitin sulfate modified 3D porous electrospun nanofiber scaffolds promote cartilage regeneration

3D electrospun nanofibrous scaffolds have been developed for cartilage regeneration, however, there is no consensus on the preferable method for biocompatible scaffolds that enhance regeneration and attenuate inflammation. We designed a 3D porous electrospun polylactic acid (PLA) @gelatin-based scaffold by a novel method. Chondroitin sulfate (CS), commonly used in clinical cartilage treatment, is capable of regulating cartilage formation and inhibiting inflammation. Thus we further functionalized the 3D scaffold by crosslinking of CS, assuming that CS-functionalized scaffold (CSS) would promote cartilage regeneration and modulate inflammation. We confirmed that CSS exhibits not only appropriate reversible compressibility and mechanical property, but also appropriate biocompatibility, allowing cell proliferation. In vitro, the potential of CSS for chondrogenic differentiation was improved compared to control and PLA@gelatin scaffold as chondrogenic markers Collagen2 and Aggrecan was significantly increased. Meanwhile, significant reduction in two crucial inflammatory factors (NO and PGE2) in CSS group demonstrated inflammation inhibition. In vivo, rabbit cartilage defects were created and CSS effectively promoted cartilage repair. Additionally, superior anti-inflammation effect of CSS was demonstrated by reduction in iNOS and PGES, enzymes producing NO and PGE2, respectively by immunohistology. Our results indicated the preferable property of CSS for cartilage regeneration and its potential in immunoregulation.

Utilization of Carbon Nanotubes in Manufacturing of 3D Cartilage and Bone Scaffolds

Cartilage and bone injuries are prevalent ailments, affecting the quality of life of injured patients. Current methods of treatment are often imperfect and pose the risk of complications in the long term. Therefore, tissue engineering is a rapidly developing branch of science, which aims at discovering effective ways of replacing or repairing damaged tissues with the use of scaffolds. However, both cartilage and bone owe their exceptional mechanical properties to their complex ultrastructure, which is very difficult to reproduce artificially. To address this issue, nanotechnology was employed. One of the most promising nanomaterials in this respect is carbon nanotubes, due to their exceptional physico-chemical properties, which are similar to collagens-the main component of the extracellular matrix of these tissues. This review covers the important aspects of 3D scaffold development and sums up the existing research tackling the challenges of scaffold design. Moreover, carbon nanotubes-reinforced bone and cartilage scaffolds manufactured using the 3D bioprinting technique will be discussed as a novel tool that could facilitate the achievement of more biomimetic structures.

Scaffolding Strategies for Tissue Engineering and Regenerative Medicine Applications

During the past two decades, tissue engineering and the regenerative medicine field have invested in the regeneration and reconstruction of pathologically altered tissues, such as cartilage, bone, skin, heart valves, nerves and tendons, and many others. The 3D structured scaffolds and hydrogels alone or combined with bioactive molecules or genes and cells are able to guide the development of functional engineered tissues, and provide mechanical support during in vivo implantation. Naturally derived and synthetic polymers, bioresorbable inorganic materials, and respective hybrids, and decellularized tissue have been considered as scaffolding biomaterials, owing to their boosted structural, mechanical, and biological properties. A diversity of biomaterials, current treatment strategies, and emergent technologies used for 3D scaffolds and hydrogel processing, and the tissue-specific considerations for scaffolding for Tissue engineering (TE) purposes are herein highlighted and discussed in depth. The newest procedures focusing on the 3D behavior and multi-cellular interactions of native tissues for further use for in vitro model processing are also outlined. Completed and ongoing preclinical research trials for TE applications using scaffolds and hydrogels, challenges, and future prospects of research in the regenerative medicine field are also presented.