Application of polyethyleneimine-modified scaffolds to the regeneration of cartilaginous tissue

Polyethylenimine Inclusion to Develop Aqueous Alginate-Based Core-Shell Capsules for Biomedical Applications

Aqueous core-shell structures can serve as an efficient approach that allows cells to generate 3D spheroids with in vivo-like cell-to-cell contacts. Here, a novel strategy for fabricating liquid-core-shell capsules is proposed by inverse gelation of alginate (ALG) and layer-by-layer (LbL) coating. We hypothesized that the unique properties of polyethylenimine (PEI) could be utilized to overcome the low structural stability and the limited cell recognition motifs of ALG. In the next step, alginate dialdehyde (ADA) enabled the Schiff-base reaction with free amine groups of PEI to reduce its possible toxic effects. Scanning electron microscopy and light microscopy images proved the formation of spherical hollow capsules with outer diameters of 3.0 ± 0.1 mm for ALG, 3.2 ± 0.1 mm for ALG/PEI, and 4.0 ± 0.2 mm for ALG/PEI/ADA capsules. The effective modulus increased by 3-fold and 5-fold when comparing ALG/PEI/ADA and ALG/PEI to ALG capsules, respectively. Moreover, PEI-coated capsules showed potential antibacterial properties against both Staphylococcus aureus and Escherichia coli, with an apparent inhibition zone. The cell viability results showed that all capsules were cytocompatible (above 75.5%). Cells could proliferate and form spheroids when encapsulated within the ALG/PEI/ADA capsules. Monitoring the spheroid thickness over 5 days of incubation indicated an increasing trend from 39.50 μm after 1 day to 66.86 μm after 5 days. The proposed encapsulation protocol represents a new in vitro platform for developing 3D cell cultivation and can be adapted to fulfill the requirements of various biomedical applications.

PEI-based functional materials: Fabrication techniques, properties, and biomedical applications

Cationic polymers have recently attracted considerable interest as research breakthroughs for various industrial and biomedical applications. They are particularly interesting due to their highly positive charges, acceptable physicochemical properties, and ability to undergo further modifications, making them attractive candidates for biomedical applications. Polyethyleneimines (PEIs), as the most extensively utilized polymers, are one of the valuable and prominent classes of polycations. Owing to their flexible polymeric chains, broad molecular weight (MW) distribution, and repetitive structural units, their customization for functional composites is more feasible. The specific beneficial attributes of PEIs could be introduced by purposeful functionalization or modification, long service life, biocompatibility, and distinct geometry. Therefore, PEIs have significant potential in biotechnology, medicine, and bioscience. In this review, we present the advances in PEI-based nanomaterials, their transfection efficiency, and their toxicity over the past few years. Furthermore, the potential and suitability of PEIs for various applications are highlighted and discussed in detail. This review aims to inspire readers to investigate innovative approaches for the design and development of next-generation PEI-based nanomaterials possessing cutting-edge functionalities and appealing characteristics.

Comparison of Hydroxyapatite/Poly(lactide-co-glycolide) and Hydroxyapatite/Polyethyleneimine Composite Scaffolds in Bone Regeneration of Swine Mandibular Critical Size Defects: In Vivo Study

Reconstruction of jaw bone defects present a significant problem because of specific aesthetic and functional requirements. Although widely used, the transplantation of standard autograft and allograft materials is still associated with significant constraints. Composite scaffolds, combining advantages of biodegradable polymers with bioceramics, have potential to overcome limitations of standard grafts. Polyethyleneimine could be an interesting novel biocompatible polymer for scaffold construction due to its biocompatibility and chemical structure. To date, there have been no in vivo studies assessing biological properties of hydroxyapatite bioceramics scaffold modified with polyethyleneimine. The aim of this study was to evaluate in vivo effects of composite scaffolds of hydroxyapatite ceramics and poly(lactide-co-glycolide) and novel polyethyleneimine on bone repair in swine's mandibular defects, and to compare them to conventional bone allograft (BioOss). Scaffolds were prepared using the method of polymer foam template in three steps. Pigs, 3 months old, were used and defects were made in the canine, premolar, and molar area of their mandibles. Four months following the surgical procedure, the bone was analyzed using radiological, histological, and gene expression techniques. Hydroxyapatite ceramics/polyethyleneimine composite scaffold demonstrated improved biological behavior compared to conventional allograft in treatment of swine's mandibular defects, in terms of bone density and bone tissue histological characteristics.

Polyethylenimine: A new differentiation factor to endothelial/cardiac tissue

Among different tissues, endothelial/cardiac types require specific factors to promote myocardial regeneration after occurred injuries. Herein, cardiac stem cells (CSCs) as the major cell population that involved in cardiovascular repair were selected to study the role of polyethyleneimine (PEI) agent on endothelial differentiation. After preparation of electrospun network of PEI with polyacrylonitrile, the related characterizations were carried out including scanning electron microscope (SEM), field-emission SEM, water contact angle, Fourier transform infrared spectroscopy and mechanical properties. Also, the release kinetic of the corresponding agent was studied up to 7 days. The cell differentiation studies were done in the following with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, Real-time polymerase chain reaction and immunostaining method. The whole obtained results approved the higher differentiation of CSCs into endothelial/cardiac cells. Finally, it is recommended that the PEI delivering increases the healing potency of CSCs and accordingly the regeneration speed of damaged cardiovascular tissue would be improved.

Stimuli-Responsive Cationic Hydrogels in Drug Delivery Applications

Stimuli-responsive, smart, intelligent, or environmentally sensitive polymers respond to changes in external stimuli such as pH, temperature, ionic strength, surfactants, pressure, light, biomolecules, and magnetic field. These materials are developed in various network architectures such as block copolymers, crosslinked hydrogels, nanogels, inter-penetrating networks, and dendrimers. Stimuli-responsive cationic polymers and hydrogels are an interesting class of "smart" materials that respond reversibly to changes in external pH. These materials have the ability to swell extensively in solutions of acidic pH and de-swell or shrink in solutions of alkaline pH. This reversible swelling-shrinking property brought about by changes in external pH conditions makes these materials useful in a wide range of applications such as drug delivery systems and chemical sensors. This article focuses mainly on the properties of these interesting materials and their applications in drug delivery systems.

Effective Adsorption of Precious Metal Palladium over Polyethyleneimine-Functionalized Alumina Nanopowder and Its Reusability as a Catalyst for Energy and Environmental Applications

Palladium is one of the widely used precious metals toward catalysis, energy, and environmental applications. Efficient recovery and reusability of palladium from the spent catalysts is not only highly desirable for sustainable industrial processing but also for preventing environmental contamination. Here, we present a facile citrate-mediated amine functionalization of alumina nanopowder (AO) in aqueous medium. The surface functionalization is probed using infrared (IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, surface area, and zeta potential measurements. The amine-functionalized sorbent is thoroughly studied for its vital palladium-sorption parameters such as amount of adsorbent, pH, adsorption capacity, thermodynamics, and kinetics. The palladium adsorption over amine-functionalized AO is further characterized with X-ray diffraction and XPS. IR analysis of palladium adsorbed over polyethyleneimine is performed to elucidate the mechanistic insight on the role of nitrogen in capturing palladium. The amine-functionalized sorbent after adsorbing palladium is studied for the catalytic reduction of 4-nitrophenol and Cr(VI) and hydrogen generation from ammonia borane, which demonstrated its excellent catalytic activity and reusability toward energy and environmental applications. The environmentally benign materials and all-aqueous reactions employed in this work demonstrate the potential of the strategy for efficient and economical industrial transformations and waste-stream management.

Cationic polymers and their therapeutic potential

The last decade has witnessed enormous research focused on cationic polymers. Cationic polymers are the subject of intense research as non-viral gene delivery systems, due to their flexible properties, facile synthesis, robustness and proven gene delivery efficiency. Here, we review the most recent scientific advances in cationic polymers and their derivatives not only for gene delivery purposes but also for various alternative therapeutic applications. An overview of the synthesis and preparation of cationic polymers is provided along with their inherent bioactive and intrinsic therapeutic potential. In addition, cationic polymer based biomedical materials are covered. Major progress in the fields of drug and gene delivery as well as tissue engineering applications is summarized in the present review.

Knee chondral injuries: clinical treatment strategies and experimental models

Articular cartilage has a very limited capacity to repair and as such premature joint degeneration is often the end point of articular injuries. Patients with chondral injury have asymptomatic periods followed by others in which discomfort or pain is bearable. The repair of focal cartilage injuries requires a precise diagnosis, a completed knee evaluation to give the correct indication for surgery proportional to the damage and adapted to each patient. Many of the surgical techniques currently performed involve biotechnology. The future of cartilage repair should be based on an accurate diagnosis using new MRI techniques. Clinical studies would allow us to establish the correct indications and surgical techniques implanting biocompatible and biodegradable matrices with or without stem cells and growth factors. Arthroscopic techniques with the design of new instruments can facilitate repair of patella and tibial plateau lesions.

Cartilage regeneration by culturing chondrocytes in scaffolds grafted with TATVHL peptide

Formation of neocartilage is a critical issue in contemporary regenerative medicine. This study presents the generation of tissue engineering cartilage in TATVHL peptide-grafted scaffolds. Bovine knee chondrocytes were seeded in TATVHL peptide-grafted scaffolds and cultured in a spinner bioreactor. The results revealed that surface TATVHL peptide enhanced the adhesion of bovine knee chondrocytes in scaffolds. However, an increase in the concentration of TATVHL peptide in scaffolds (up to 20 μg/mL) did not cause an evident variation in the cell viability. Surface TATVHL peptide was effective in promoting the quantity of cartilaginous components in constructs after dynamic cultivation. Biochemical assay, scanning electron microscope images, and histological staining demonstrated that surface TATVHL peptide accelerated the proliferation of bovine knee chondrocytes in constructs. In addition, the secretion of glycosaminoglycans and production of collagen in TATVHL peptide-grafted constructs were faster than those in TATVHL peptide-free constructs. TATVHL peptide can be a promising bioactive molecule to improve chondrogenesis in porous biomaterials.

Heparin-conjugated scaffolds with pore structure of inverted colloidal crystals for cartilage regeneration

A uniform de novo production of neocartilage is a critical issue in the fabrication of tissue-engineered diarthrodial substitutes. The aim of this work is to develop homogeneous chondrogenesis in heparinized scaffolds with pores of inverted colloidal crystal (ICC) geometry. Monodispersed polystyrene microspheres were self-assembled by floating in the medium containing ethylene glycol, dried, annealed and infiltrated with heparin/chitin/chitosan gels. The results indicated that the colloidal template was in a structure of hexagonal arrays. In addition, the regularity of the organized pores in the scaffolds reduced when the concentration of ethylene glycol decreased. An increase in the weight percentage of heparin enhanced the viability of bovine knee chondrocytes (BKCs) in ICC matrices. Over 4 weeks of cultivation, the amount of cartilaginous components including BKCs, glycosaminoglycans (GAGs) and collagen enhanced with time. Moreover, an increase in the weight percentage of heparin promoted the production of BKCs, GAGs and collagen in ICC constructs. Histological and immunochemical staining of the cultured ICC constructs revealed minor differences in BKCs, GAGs and type II collagen between the peripheral and core regions. Therefore, the ordered pores in the heparinized ICC constructs could favor the chondrocyte culture to regenerate a uniform distribution of cartilage.