Scaffolds For Tissue Engineering Research Articles

Recent Applications of Chitosan and Its Derivatives in Antibacterial, Anticancer, Wound Healing, and Tissue Engineering Fields

Chitosan, a versatile biopolymer derived from chitin, has garnered significant attention in various biomedical applications due to its unique properties, such as biocompatibility, biodegradability, and mucoadhesiveness. This review provides an overview of the diverse applications of chitosan and its derivatives in the antibacterial, anticancer, wound healing, and tissue engineering fields. In antibacterial applications, chitosan exhibits potent antimicrobial properties by disrupting microbial membranes and DNA, making it a promising natural preservative and agent against bacterial infections. Its role in cancer therapy involves the development of chitosan-based nanocarriers for targeted drug delivery, enhancing therapeutic efficacy while minimising side effects. Chitosan also plays a crucial role in wound healing by promoting cell proliferation, angiogenesis, and regulating inflammatory responses. Additionally, chitosan serves as a multifunctional scaffold in tissue engineering, facilitating the regeneration of diverse tissues such as cartilage, bone, and neural tissue by promoting cell adhesion and proliferation. The extensive range of applications for chitosan in pharmaceutical and biomedical sciences is not only highlighted by the comprehensive scope of this review, but it also establishes it as a fundamental component for forthcoming research in biomedicine.

Quantitative Evaluation of the Pore and Window Sizes of Tissue Engineering Scaffolds on Scanning Electron Microscope Images Using Deep Learning

Quantitative Evaluation of the Pore and Window Sizes of Tissue Engineering Scaffolds on Scanning Electron Microscope Images Using Deep Learning

Can self-powered piezoelectric materials be used to treat disc degeneration by means of electrical stimulation?

Intervertebral disc degeneration (IDD) due to multiple causes is one of the major causes of low back pain (LBP). A variety of traditional treatments and biologic therapies are currently used to delay or even reverse IDD; however, these treatments still have some limitations. Finding safer and more effective treatments is urgent for LBP patients. With increasing reports it has been found that the intervertebral disc (IVD) can convert pressure loads from the spine into electrical stimulation in a variety of ways, and that this electrical stimulation is of great importance in modulating cell behavior, the immune microenvironment and promoting tissue repair. However, when intervertebral disc degeneration occurs, the normal structures within the IVD are destroyed. This eventually leads to a weakening or loss of self-powered. Currently various piezoelectric materials with unique crystal structures can mimic the piezoelectric effect of normal tissues. Based on this, tissue-engineered scaffolds prepared using piezoelectric materials have been widely used for regenerative repair of various types of tissues, however, there are no reports of their use for the treatment of IDD. For this reason, we propose to utilize tissue-engineered scaffolds prepared from piezoelectric biomaterials with excellent biocompatibility and self-powered properties to be implanted into degenerated IVD to help restore cell type and number, restore extracellular matrix, and modulate immune responses. It provides a feasible and novel therapeutic approach for the clinical treatment of IDD.

Low-Temperature Deposited Amorphous Poly(aryl ether ketone) Hierarchically Porous Scaffolds with Strontium-Doped Mineralized Coating for Bone Defect Repair.

In recent years, the demand for clinical bone grafting has increased. As a new solution for orthopedic implants, polyether ether ketone (PEEK, crystalline PAEK) has excellent comprehensive performance and has been practically applied in clinic. In this research, a noteworthy elevated scheme to enhance the performance of PEEK scaffolds was presented. The amorphous aggregated poly (aryl ether ketone) (PAEK) resin was prepared as the matrix material, which maintained high mechanical strength and could be processed through solution. So, the tissue engineering scaffolds with multilevel pores could be printed by low-temperature deposited manufacturing (LDM) to improve biologically inert scaffolds with smooth surfaces. Also, the feature of PAEK's solution processing is profitable to uniformly add the functional components for bone repair. Ultimately, A system of orthopedic implantable PAEK material based on intermolecular interactions, surface topology, and surface modification was established. The specific steps include synthesizing PAEK that contain polar carboxyl structures, preparing bioinks and fabricating scaffolds by LDM, preparation of scaffolds with strontium-doped mineralized coatings, evaluation of their osteogenic properties in vitro and in vivo, and investigation on the effect and mechanism of scaffolds in promoting osteogenic differentiation. This work provides an upgraded system of PAEK implantable materials for clinical application. This article is protected by copyright. All rights reserved.

Challenges in Application: Gelation Strategies of DAT-Based Hydrogel Scaffolds.

Decellularized adipose tissue (DAT) has great clinical applicability, owing to its abundant source material, natural extracellular matrix microenvironment, and nonimmunogenic attributes, rendering it a versatile resource in the realm of tissue engineering. However, practical implementations are confronted with multifarious limitations. Among these, the selection of an appropriate gelation strategy serves as the foundation for adapting to diverse clinical contexts. The cross-linking strategies under varying physical or chemical conditions exert profound influences on the ultimate morphology and therapeutic efficacy of DAT. This review sums up the processes of DAT decellularization and subsequent gelation, with a specific emphasis on the diverse gelation strategies employed in recent experimental applications of DAT. The review expounds upon methodologies, underlying principles, and clinical implications of different gelation strategies, aiming to offer insights and inspiration for the application of DAT in tissue engineering and advance research for tissue engineering scaffold development.

Periapical lesion-derived decellularized extracellular matrix as a potential solution for regenerative endodontics

Abstract Pulp regeneration remains a crucial target in the preservation of natural dentition. Using decellularized extracellular matrix is an appropriate approach to mimic natural microenvironment and facilitate tissue regeneration. In this study, we attempted to obtain decellularized extracellular matrix from periapical lesions (PL-dECM) and evaluate its bioactive effects. The decellularization process yielded translucent and viscous PL-dECM, meeting the standard requirements for decellularization efficiency. Proteomic sequencing revealed that the PL-dECM retained essential extracellular matrix components and numerous bioactive factors. The PL-dECM conditioned medium could enhance the proliferation and migration ability of periapical lesion-derived stem cells (PLDSCs) in a dose-dependent manner. Culturing PLDSCs on PL-dECM slices improved odontogenic/angiogenic ability compared to the type I collagen group. In vivo, the PL-dECM demonstrated a sustained supportive effect on PLDSCs and promoted odontogenic/angiogenic differentiation. Both in vitro and in vivo studies demonstrated that PL-dECM served as an effective scaffold for pulp tissue engineering, providing valuable insights into PLDSCs differentiation. These findings pave avenues for the clinical application of dECM's in situ transplantation for regenerative endodontics.

A Pump-Free Strategy for the Controllable Generation of Alginate Microgels as Cellular Microcarriers.

Microgels are advanced scaffolds for tissue engineering due to their proper biodegradability, good biocompatibility, and high specific surface area for effective oxygen and nutrient transfer. However, most of the current monodispersed microgel fabrication systems rely heavily on various precision pumps, which highly increase the cost and complexity of their downstream application. In this work, we developed a simple and facile system for the controllable generation of uniform alginate microgels by integrating a gas-shearing strategy into a glass microfluidic device. Importantly, the cell-laden microgels can be rapidly prepared in a pump-free manner under an all-aqueous environment. The three-dimensional cultured green fluorescent protein-human A549 cells in alginate microgels exhibited enhanced stemness and drug resistance compared to those under two-dimensional conditions. The pancreatic cancer organoids in alginate microgels exhibited some of the key features of pancreatic cancer. The proposed microgels showed decent monodispersity, biocompatibility, and versatility, providing great opportunities in various biomedical applications such as microcarrier fabricating, organoid engineering, and high-throughput drug screening.

CT-Visible Microspheres Enable Whole-Body In Vivo Tracking of Injectable Tissue Engineering Scaffolds.

Targeted delivery and retention are essential requirements for implantable tissue-engineered products. Non-invasive imaging methods that can confirm location, retention, and biodistribution of transplanted cells attached to implanted tissue engineering scaffolds will be invaluable for the optimization and enhancement of regenerative therapies. To address this need, an injectable tissue engineering scaffold consisting of highly porous microspheres compatible with transplantation of cells is modified to contain the computed tomography (CT) contrast agent barium sulphate (BaSO4). The trackable microspheres show high x-ray absorption, with contrast permitting whole-body tracking. The microspheres are cellularized with GFP+ Luciferase+ mesenchymal stem cells and show in vitro biocompatibility. In vivo, cellularized BaSO4-loaded microspheres are delivered into the hindlimb of mice where they remain viable for 14 days. Co-registration of 3D-bioluminescent imagingand µCT reconstructions enable the assessment of scaffold material and cell co-localization. The trackable microspheres are also compatible with minimally-invasive delivery by ultrasound-guided transthoracic intramyocardial injections in rats. These findings suggest that BaSO4-loaded microspheres can be used as a novel tool for optimizing delivery techniques and tracking persistence and distribution of implanted scaffold materials. Additionally, the microspheres can be cellularized and have the potential to be developed into an injectable tissue-engineered combination product for cardiac regeneration.

Dimensional and Structural Instability of Electrospun Polylactic Acid Membranes in Liquid Environments: Role of Water, Ethanol, and Temperature

AbstractElectrospun nanofibres of polylactic acid (PLA) are suggested for a variety of uses, including scaffolds for tissue engineering, components of drug delivery devices, sustainable packaging materials and membranes for liquid filtration/purification. For all these applications, it is critical to consider the stability of the PLA electrospun materials once in operation. Exposure to certain liquids and temperatures can modify their dimensions, shape, surface topography and mechanical response and compromise their performance. In this study, electrospun PLA mats were exposed to water and ethanol solutions, at different temperatures and for defined time periods, and changes in their properties were analysed. It was found that the impact of water on area shrinkage and fibre arrangement strongly depended on temperature, particularly if the treatment was performed at the glass transition temperature of PLA. Ethanol, instead, induced significant alterations in the size, morphology, and elastic modulus of the electrospun mats, even at room temperature and determined the formation of crimped structures. This work provides insights into the conditions that can critically affect the properties of PLA electrospun fibres and, hence, impact on their usage.

Physical cues of scaffolds promote peripheral nerve regeneration

The effective treatment of long-gap peripheral nerve injury (PNI) remains a challenge in clinical settings. The autograft, the gold standard for the long-gap PNI therapy, has several limitations, including a limited supply of donor nerve, size mismatch between the donor and recipient sites, functional loss at the donor site, neuroma formation, and the requirement for two operations. With the increasing abundance of biocompatible materials with adjustable structures and properties, tissue engineering provides a promising avenue for bridging peripheral nerve gaps and addressing the above issues of autograft. The physical cues provided by tissue engineering scaffolds, essential for regulating the neural cell fate and microenvironments, have received considerable research attention. This review elaborates on three major physical cues of tissue engineering scaffolds for peripheral nerve regeneration: topological structure, mechanical support, and electrical stimulation. These three aspects are analogs to Lego bricks, wherein different combinations result in diverse functions. Innovative and more effective bricks, along with multi-level and all-around integration, are expected to provide new advances in tissue engineering for peripheral nerve generation.

Stem Cell‐Based Therapies and Tissue Engineering Innovations for Tendinopathy: A Comprehensive Review of Current Strategies and Future Directions

AbstractTendon diseases commonly lead to physical disability, exerting a profound impact on the routine of affected patients. These conditions respond poorly to existing treatments, presenting a substantial challenge for orthopedic scientists. Research into clinical translational therapy has yet to yield highly versatile interventions capable of effectively addressing tendon diseases, including tendinopathy. Stem cell‐based therapies have emerged as a promising avenue for modifying the biological milieu through the secretion of regenerative and immunomodulatory factors. The current review provides an overview of the intricate tendon microenvironment, encompassing various tendon stem progenitor cells within distinct tendon sublocations, gene regulation, and pathways pertinent to tendon development, and the pathology of tendon diseases. Subsequently, the advantages of stem cell‐based therapies are discussed that utilize distinct types of autologous and allogeneic stem cells for tendon regeneration at the translational level. Moreover, this review outlines the challenges, gaps, and future innovations to propose a consolidated stem cell‐based therapy to treat tendinopathy. Finally, regenerative soluble therapies, insoluble bio‐active therapies, along with insoluble bio‐active therapies, and implantable 3D scaffolds for tendon tissue engineering are discussed, thereby presenting a pathway toward enhanced tissue regeneration and engineering.

Engineering Cell Instructive Microenvironments for In Vitro Replication of Functional Barrier Organs.

Multicellular organisms exhibit synergistic effects among their components, giving rise to emergent properties crucial for their genesis and overall functionality and survival. Morphogenesis involves and relies upon intricate and biunivocal interactions among cells and their environment, that is, the extracellular matrix (ECM). Cells secrete their own ECM, which in turn, regulates their morphogenetic program by controlling time and space presentation of matricellular signals. The ECM, once considered passive, is now recognized as an informative space where both biochemical and biophysical signals are tightly orchestrated. Replicating this sophisticated and highly interconnected informative media in a synthetic scaffold for tissue engineering is unattainable with current technology and this limits the capability to engineer functional human organs in vitro and in vivo. This review explores current limitations to in vitro organ morphogenesis, emphasizing the interplay of gene regulatory networks, mechanical factors, and tissue microenvironment cues. In vitro efforts to replicate biological processes for barrier organs such as the lung and intestine, are examined. The importance of maintaining cells within their native microenvironmental context is highlighted to accurately replicate organ-specific properties. The review underscores the necessity for microphysiological systems that faithfully reproduce cell-native interactions, for advancing the understanding of developmental disorders and disease progression.

Continuous fabrication of braided composite nanofibrous surgical yarns using advanced AC electrospinning and braiding technology

Composite nanofibrous yarns (CNY), featuring a submicron electrospun sheath coated on a micro-scale core yarn have gained attention within the academic and industrial communities due to their unique structure. When braided, these CNYs hold great promise as next-generation surgical yarns. However, large-scale production of CNYs using conventional electrospinning techniques remains technologically challenging, and maintaining the integrity of the fibrous sheath during braiding presents further difficulties. Here, we propose a novel approach for continuously fabricating functional braided CNYs using collectorless alternating current (AC) electrospinning and braiding technology. Our approach utilized polycaprolactone-polylactic acid (PCL-PLA) blends and PCL-PLA with chlorhexidine (CHX) or triclosan (TRC) electrospun fibers for the sheath layer, while PLA micro-yarns acted as the core layer. Morphological analyses confirmed the successful fabrication of braided CNYs. Additionally, infrared spectroscopy validated the presence of CHX or TRC in the resulting yarns. The resulting braided CNYs exhibited excellent breaking force (29 N) and thermal stability (270 °C). Cytotoxicity and antibacterial assessments demonstrated that CHX-loaded braided CNYs could serve as biocompatible antibacterial surgical sutures. The proposed method offers a versatile approach for producing various functional braided CNYs applicable in tissue engineering scaffolds, filters, wearable electronics, and sensors.

Silk fibroin incorporated electrospun aliphatic polyester nanofiber scaffolds with excellent dimensional stability and cytocompatibility

Poly (lactide-co-glycolide) (PLGA) has been extensively utilized to fabricate electrospun fibers for tissue engineering scaffolds due to its good biocompatibility and biodegradability. However, such scaffolds in biological media shrink and distort severely, which is undesired for practical application. In this study, a silk fibroin incorporated electrospun aliphatic polyester nanofiber scaffold (PLGA/PCL/SF) was developed via facile one-step electrospinning, with PLGA as the substrate and incorporating polycaprolactone (PCL) and silk fibroin (SF). The resulting scaffold exhibited fine fibers and water absorbency. Particularly, the addition of SF into scaffolds improved the water adsorption ability, and that of PCL effectively prevented scaffold shrinkage behaviors. In vitro degradation analyses showed that it was accelerating for the obtained scaffolds with SF added, without any undesirable acidic environment induced. Additionally, the PLGA/PCL/SF scaffold exhibited the most promising result in cell proliferation, presenting a valuable insight into the design of tissue engineering scaffolds.

Silk-Based 3D Porous Scaffolds for Tissue Engineering.

Silk fibroin, extracted from the silk of the Bombyx mori silkworm, stands out as a biomaterial due to its nontoxic nature, excellent biocompatibility, and adjustable biodegradability. Porous scaffolds, a type of biomaterial, are crucial for creating an optimal microenvironment that supports cell adhesion and proliferation, thereby playing an essential role in tissue remodeling and repair. Therefore, this review focuses on 3D porous silk fibroin-based scaffolds, first summarizing their preparation methods and then detailing their regenerative effects on bone, cartilage, tendon, vascular, neural, skin, hepatic, and tracheal epithelial tissue engineering in recent years.

Fabrication, Characterization of Curcumin Loaded Alginate Chitosan for Potential Wound Healing Applications

The most employed scaffolds in tissue engineering are alginate and chitosan due to their properties like biodegradability, compatibility, and structural similarity to that of the ECM. Curcumin, together with scaffolds such as alginate and chitosan, can improve wound healing properties by tissue repair and regeneration. This study aims to load curcumin into alginate chitosan scaffolds and to analyze their potential wound healing properties by characterization and checking their biocompatibility. Curcumin was loaded into the alginate-chitosan scaffold. It was then characterized using Fourier Transform-InfraRed (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM). Annexin V PI apoptotic assay and Hemolytic assay were done to screen its biocompatibility. FT-IR has strong absorption bands at 3237, 2359, 1597, 1406, 1025, and 947 cm−1. SEM analysis of the curcumin-loaded alginate-chitosan scaffold showed the dispersed curcumin on the surface of the porous scaffold. Our results suggest that the curcumin-loaded alginate-chitosan scaffold possesses greater biocompatibility towards peripheral blood mononuclear cells (PBMC) which was confirmed by Annexin V - PI assay and hemolytic assay. Curcumin loaded onto an alginate-chitosan scaffold is reported to be biocompatible using flow cytometry and hemolytic assay. However a more detailed study must be done before using it for potential wound healing applications.

3D bioprinting in otorhinolaryngology: from bench to clinical application

Three-dimensional (3D) bioprinting is a promising additive manufacturing technology that uses imaging data and computer-assisted deposition of biological materials or cells to reconstruct complex 3D structures accurately. This technology has progressed rapidly, in part because of its integration across multiple disciplines and combination with other technologies for clinical applications. Advances in experimental research and clinical applications related to otorhinolaryngology have led to the development of diagnostic and treatment methods based on 3D bioprinting, including the development of tissue engineering scaffolds, biosensors, organ chips, and organoids, surgical planning, graft construction, and medical education. Additionally, otorhinolaryngologists will be better equipped to treat tissue function defects with personalized printed graft implants. It is also expected that 3D printing can be used to build ideal in vitro models in the future to help solve existing research challenges. This article briefly introduces the relevant 3D bioprinting technologies and bioinks that can be used by otorhinolaryngologists and discusses their potential applications in otorhinolaryngology.

Customized bioresin formulation for stereolithography in tissue engineering

Recently, advancements in fabrication technology have brought a new aspect to the field of tissue engineering. By utilizing advanced techniques in 3D manufacturing and biomaterials, scientists have successfully created tissue engineering scaffolds with complex three-dimensional structures and customized chemical compositions that closely mimic the natural environment of living tissues. These methodologies show potential not only for developing therapies that restore lost tissue function but also for creating in vitro models that replicate living tissue. The current investigation involved the synthesis of methacrylated polycaprolactone (PCLMA) by incorporating methacryloyl chloride (Meth-Cl) into polycaprolactone (PCL) with a molecular weight of 80,000 Da. Afterwards, PCLMA was subjected to crosslinking with glycerol acrylate (GA) and, by utilizing Diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as a photoinitiator, achieved the three-dimensional (3D) printing of tissue materials using Stereolithography (SLA). Analytical techniques included nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Cell viability was investigated using Human Osteoblast (HOB) cells. The biocompatibility of glycerol acrylate (GA) crosslinked polymethacrylated polycaprolactone (PCLMA) was confirmed using cell viability experiments. Overall, the GA-crosslinked PCLMA bioresin, particularly PCLMA-8, shows promise for further use in tissue engineering applications.

Cell Instructive Behavior of Composite Scaffolds in a Co-Culture of Human Mesenchymal Stem Cells and Peripheral Blood Mononuclear Cells

The in vitro evaluation of 3D scaffolds for bone tissue engineering in mono-cultures is a common practice; however, it does not represent the native complex nature of bone tissue. Co-cultures of osteoblasts and osteoclasts, without the addition of stimulating agents for monitoring cellular cross-talk, remains a challenge. In this study, a growth factor-free co-culture of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and human peripheral blood mononuclear cells (hPBMCs) has been established and used for the evaluation of 3D-printed scaffolds for bone tissue engineering. The scaffolds were produced from PLLA/PCL/PHBV polymeric blends, with two composite materials produced through the addition of 2.5% w/v nanohydroxyapatite (nHA) or strontium-substituted nanohydroxyapatite (Sr-nHA). Cell morphology data showed that hPBMCs remained undifferentiated in co-culture, while no obvious differences were observed in the mono- and co-cultures of hBM-MSCs. A significantly increased alkaline phosphatase (ALP) activity and osteogenic gene expression was observed in co-culture on Sr-nHA-containing scaffolds. Tartrate-resistant acid phosphatase (TRAP) activity and osteoclastogenic gene expression displayed significantly suppressed levels in co-culture on Sr-nHA-containing scaffolds. Interestingly, mono-cultures of hPBMCs on Sr-nHA-containing scaffolds indicated a delay in osteoclasts formation, as evidenced from TRAP activity and gene expression, demonstrating that strontium acts as an osteoclastogenesis inhibitor. This co-culture study presents an effective 3D model to evaluate the regenerative capacity of scaffolds for bone tissue engineering, thus minimizing time-consuming and costly in vivo experiments.

Biodegradable electrospun poly(L-lactide-co-ε-caprolactone)/polyethylene glycol/bioactive glass composite scaffold for bone tissue engineering.

The field of tissue engineering has witnessed significant advancements in recent years, driven by the pursuit of innovative solutions to address the challenges of bone regeneration. In this study, we developed an electrospun composite scaffold for bone tissue engineering. The composite scaffold is made of a blend of poly(L-lactide-co-ε-caprolactone) (PLCL) and polyethylene glycol (PEG), with the incorporation of calcined and lyophilized silicate-chlorinated bioactive glass (BG) particles. Our investigation involved a comprehensive characterization of the scaffold's physical, chemical, and mechanical properties, alongside an evaluation of its biological efficacy employing alveolar bone-derived mesenchymal stem cells. The incorporation of PEG and BG resulted in elevated swelling ratios, consequently enhancing hydrophilicity. Thermal gravimetric analysis confirmed the efficient incorporation of BG, with the scaffolds demonstrating thermal stability up to 250°C. Mechanical testing revealed enhanced tensile strength and Young's modulus in the presence of BG; however, the elongation at break decreased. Cell viability assays demonstrated improved cytocompatibility, especially in the PLCL/PEG+BG group. Alizarin red staining indicated enhanced osteoinductive potential, and fluorescence analysis confirmed increased cell adhesion in the PLCL/PEG+BG group. Our findings suggest that the PLCL/PEG/BG composite scaffold holds promise as an advanced biomaterial for bone tissue engineering.