Engineering of Extracellular Matrix‐Like Biomaterials at Nano‐ and Macroscale toward Fabrication of Hierarchical Scaffolds for Bone Tissue Engineering

Development of sterile platform for quantification of extracellular analytes via single walled carbon nanotubes

Progress has been made studying cell-cell signaling communication processes. However, due to limitations of current sensors on time and spatial resolution, the role of many extracellular analytes is still unknown. A single walled carbon nanotube (SWNT) platform was previously developed based on the avidin-biotin immobilization of SWNT to a glass substrate. The SWNT platform provides real time feedback about analyte concentration and has a high concentration of evenly distributed sensors, both of which are essential for the study of extracellular analytes. Unfortunately, this initial SWNT platform is synthesized through unsterile conditions and cannot be sterilized post-production due to the delicate nature of the sensors, making it unsuitable for in vitro work. Herein the multiple-step process for SWNT immobilization is modified and the platform's biocompatibility is assessed in terms of sterility, cytotoxicity, cell proliferation, and cell morphology through comparison with non-sensors controls. The results demonstrate the SWNT platform's sterility and lack of toxicity over 72 h. The proliferation rate and morphology profiles for cells growing on the SWNT platform are similar to those grown on tissue culture substrates. This novel nano-sensor platform preserves cell health and cell functionality over time, offering opportunities to study extracellular analytes gradients in cellular communication.

Current Perspectives of Protein in Bone Tissue Engineering: Bone Structure, Ideal Scaffolds, Fabrication Techniques, Applications, Scopes, and Future Advances

In view of their exceptional approach, excellent inherent biocompatibility and biodegradability properties, and interaction with the local extracellular matrix, protein-based polymers have received attention in bone tissue engineering, which is a multidisciplinary field that repairs and regenerates fractured bones. Bone is a multihierarchical complex structure, and it performs several essential biofunctions, including maintaining mineral balance and structural support and protecting soft organs. Protein-based polymers have gained interest in developing ideal scaffolds as emerging biomaterials for bone fractured healing and regeneration, and it is challenging to design ideal bone substitutes as perfect biomaterials. Several protein-based polymers, including collagen, keratin, gelatin, serum albumin, etc., are potential materials due to their inherent cytocompatibility, controlled biodegradability, high biofunctionalization, and tunable mechanical characteristics. While numerous studies have indicated the encouraging possibilities of proteins in BTE, there are still major challenges concerning their biodegradability, stability in physiological conditions, and continuous release of growth factors and bioactive molecules. Robust scaffolds derived from proteins can be used to replace broken or diseased bone with a biocompatible substitute; proteins, being biopolymers, provide excellent scaffolds for bone tissue engineering. Herein, recent developments in protein polymers for cutting-edge bone tissue engineering are addressed in this review within 3-5 years, with a focus on the significant challenges and future perspectives. The first section discusses the structural fundamentals of bone anatomy and ideal scaffolds, and the second section describes the fabrication techniques of scaffolds. The third section highlights the importance of proteins and their applications in BTE. Hence, the recent development of protein polymers for state-of-the-art bone tissue engineering has been discussed, highlighting the significant challenges and future perspectives.

Bone regeneration driven by a nano-hydroxyapatite/chitosan composite bioaerogel for periodontal regeneration

The most recent progress in reconstructive therapy for the management of periodontitis and peri-implantitis bone defects has relied on the development of highly porous biodegradable bioaerogels for guided bone regeneration. The objective of this work was to evaluate in vitro the osteoinduction of periodontal-originating cells (human dental follicle mesenchymal cells, DFMSCs) promoted by a nano-hydroxyapatite/chitosan (nHAp/CS) bioaerogel, which was purified and sterilized by a sustainable technique (supercritical CO2). Moreover, the in vivo bone regeneration capacity of the nHAp/CS bioaerogel was preliminarily assessed as a proof-of-concept on a rat calvaria bone defect model. The quantification of DNA content of DFMSCs seeded upon nHAp/CS and CS scaffolds (control material) showed a significant increase from the 14th to the 21st day of culture. These results were corroborated through confocal laser scanning microscopy analysis (CLSM). Furthermore, the alkaline phosphatase (ALP) activity increased significantly on the 21st day, similarly for both materials. Moreover, the presence of nHAp promoted a significantly higher expression of osteogenic genes after 21 days when compared to CS scaffolds and control. CLSM images of 21 days of culture also showed an increased deposition of OPN over the nHAp/CS surface. The in vivo bone formation was assessed by microCT and histological analysis. The in vivo evaluation showed a significant increase in bone volume in the nHAp/CS test group when compared to CS and the empty control, as well as higher new bone formation and calcium deposition within the nHAp/CS structure. Overall, the present study showed that the nHAp/CS bioaerogel could offer a potential solution for periodontal and peri-implant bone regeneration treatments since the in vitro results demonstrated that it provided favorable conditions for DFMSC proliferation and osteogenic differentiation, while the in vivo outcomes confirmed that it promoted higher bone ingrowth.

Towards Stem Cell Therapy for Critical-Sized Segmental Bone Defects: Current Trends and Challenges on the Path to Clinical Translation

The management and reconstruction of critical-sized segmental bone defects remain a major clinical challenge for orthopaedic clinicians and surgeons. In particular, regenerative medicine approaches that involve incorporating stem cells within tissue engineering scaffolds have great promise for fracture management. This narrative review focuses on the primary components of bone tissue engineering-stem cells, scaffolds, the microenvironment, and vascularisation-addressing current advances and translational and regulatory challenges in the current landscape of stem cell therapy for critical-sized bone defects. To comprehensively explore this research area and offer insights for future treatment options in orthopaedic surgery, we have examined the latest developments and advancements in bone tissue engineering, focusing on those of clinical relevance in recent years. Finally, we present a forward-looking perspective on using stem cells in bone tissue engineering for critical-sized segmental bone defects.

Biotechnological applications of amyloid fibrils

Protein aggregates and amyloid fibrils have special qualities and are used in a variety of biotechnological applications. They are extensively employed in bioremediation, biomaterials, and biocatalysis. Because of their capacity to encapsulate and release pharmaceuticals and their sensitivity to certain molecules, respectively, they are also used in drug delivery and biosensor applications. They have also demonstrated potential in the domains of food and bioremediation. Additionally, amyloid peptides have drawn interest in biological applications, especially in the investigation of illnesses like Parkinson's and Alzheimer's. The unique characteristics of amyloid fibrils, namely their mechanical strength and β-sheet structure, make them adaptable to a wide range of biotechnological uses. Even with their promise, one important factor to keep in mind before widely using modified amyloid materials is their potential toxicity. Thus, current research aims to overcome safety concerns while maximizing their potential.

3D cotton-type anisotropic biomimetic scaffold with low fiber motion electrospun via a sharply inclined array collector for induced osteogenesis

Electrospinning is an effective method to fabricate fibrous scaffolds that mimic the ECM of bone tissue on a nano- to macro-scale. However, a limitation of electrospun fibrous scaffolds for bone tissue engineering is the structure formed by densely compacted fibers, which significantly impedes cell infiltration and tissue ingrowth. To address this problem, several researchers have developed numerous techniques for fabricating 3D fibrous scaffolds with customized topography and pore size. Despite the success in developing various 3D electrospun scaffolds based on fiber repulsion, the lack of contact points between fibers in those scaffolds has been shown to hinder cell attachment, migration, proliferation, and differentiation due to excessive movement of the fibers. In this article, we introduce a Dianthus caryophyllus-inspired scaffold fabricated using SIAC-PE, a modified collector under specific viscosity conditions of PCL/LA solution. The developed scaffold mimicking the structural similarities of the nature-inspired design presented enhanced cell proliferation, infiltration, and increased expression of bone-related factors by reducing fiber movements, presenting high space interconnection, high porosity, and controlled fiber topography.

Attributes of Nanomaterials and Nanotopographies for Improved Bone Tissue Engineering and Regeneration

Bone tissue engineering (BTE) is a multidisciplinary area that can solve the limitation of conventional grafting methods by developing viable and biocompatible bone replacements. The three essential components of BTE, i.e., Scaffold material and Cells and Growth factors altogether, facilitate support and guide for bone formation, differentiation of the bone tissues, and enhancement in the cellular activities and bone regeneration. However, there is a scarcity of the appropriate materials that can match the mechanical property as well as functional similarity to native tissue, considering the bone as hard tissue. In such scenarios, nanotechnology can be leveraged upon to achieve the desired aspects of BTE, and that is the key point of this review article. This review article examines the significant areas of nanotechnology research that have an impact on regeneration of bone: (a) scaffold with nanomaterials helps to enhance physicochemical interactions, biocompatibility, mechanical stability, and attachment; (b) nanoparticle-based approaches for delivering bioactive chemicals, growth factors, and genetic material. The article begins with the introduction of components and healing mechanisms of bone and the factors associated with them. The focus of this article is on the various nanotopographies that are now being used in scaffold formation, by describing how they are made, and how these nanotopographies affect the immune system and potential underlying mechanisms. The advantages of 4D bioprinting in BTE by using nanoink have also been mentioned. Additionally, we have investigated the importance of an in silico approach for finding the interaction between drugs and their related receptors, which can help to formulate suitable systems for delivery. This review emphasizes the role of nanoscale approach and how it helps to increase the efficacy of parameters of scaffold as well as drug delivery system for tissue engineering and bone regeneration.

Fundamental concepts of protein therapeutics and spacing in oncology: an updated comprehensive review

Current treatment regimens in cancer cases cause significant side effects and cannot effectively eradicate the advanced disease. Hence, much effort has been expended over the past years to understand how cancer grows and responds to therapies. Meanwhile, proteins as a type of biopolymers have been under commercial development for over three decades and have been proven to improve the healthcare system as effective medicines for treating many types of progressive disease, such as cancer. Following approving the first recombinant protein therapeutics by FDA (Humulin), there have been a revolution for drawing attention toward protein-based therapeutics (PTs). Since then, the ability to tailor proteins with ideal pharmacokinetics has provided the pharmaceutical industry with an important noble path to discuss the clinical potential of proteins in oncology research. Unlike traditional chemotherapy molecules, PTs actively target cancerous cells by binding to their surface receptors and the other biomarkers particularly associated with tumorous or healthy tissue. This review analyzes the potential and limitations of protein therapeutics (PTs) in the treatment of cancer as well as highlighting the evolving strategies by addressing all possible factors, including pharmacology profile and targeted therapy approaches. This review provides a comprehensive overview of the current state of PTs in oncology, including their pharmacology profile, targeted therapy approaches, and prospects. The reviewed data show that several current and future challenges remain to make PTs a promising and effective anticancer drug, such as safety, immunogenicity, protein stability/degradation, and protein-adjuvant interactions.

Enzyme-Triggered Crosslinked Hybrid Hydrogels for Bone Tissue Engineering

The quest to develop state-of-the-art hydrogels for bone tissue engineering has accompanied substantial innovation and significant progression in the field of bioactive hydrogels. Still, there is scope for advancement in this cell-friendly and biocompatible scaffold system. The crosslinking approaches used for hydrogel synthesis plays a decisive role in guiding and regulating the mechanical stability, network framework, macroscopic architect, immunological behaviors, and cellular responses. Until recently, enzyme-based crosslinking strategies were considered as the pinnacle in designing efficient hybrid hydrogel systems. A variety of enzymes have been explored for manufacturing hydrogels while taking the advantage of the biocompatible nature, specificity, ability to produce nontoxic by products and high efficiency of enzymes. The current review focuses on the utility of different enzymes as crosslinking agents for hydrogel formation with their application in bone tissue engineering. The field of enzyme crosslinked hydrogel synthesis is rapidly maturing with a lot of opportunities to be explored in bone tissue engineering. Enzyme-based in situ and externally crosslinked hydrogels for bone regeneration is an attractive field, and with innovation in using engineered enzymes this field will continue to flourish with clinical orientation.

Application of Nano-Inspired Scaffolds-Based Biopolymer Hydrogel for Bone and Periodontal Tissue Regeneration

This review's objectives are to provide an overview of the various kinds of biopolymer hydrogels that are currently used for bone tissue and periodontal tissue regeneration, to list the advantages and disadvantages of using them, to assess how well they might be used for nanoscale fabrication and biofunctionalization, and to describe their production processes and processes for functionalization with active biomolecules. They are applied in conjunction with other materials (such as microparticles (MPs) and nanoparticles (NPs)) and other novel techniques to replicate physiological bone generation more faithfully. Enhancing the biocompatibility of hydrogels created from blends of natural and synthetic biopolymers can result in the creation of the best scaffold match to the extracellular matrix (ECM) for bone and periodontal tissue regeneration. Additionally, adding various nanoparticles can increase the scaffold hydrogel stability and provide a number of biological effects. In this review, the research study of polysaccharide hydrogel as a scaffold will be critical in creating valuable materials for effective bone tissue regeneration, with a future impact predicted in repairing bone defects.