Synthesis and Characterization of Injectable Hydrogels with Varying Collagen⁻Chitosan⁻Thymosin β4 Composition for Myocardial Infarction Therapy

Designing Composite Stimuli-Responsive Hydrogels for Wound Healing Applications: The State-of-the-Art and Recent Discoveries

Effective wound treatment has become one of the most important challenges for healthcare as it continues to be one of the leading causes of death worldwide. Therefore, wound care technologies significantly evolved in order to provide a holistic approach based on various designs of functional wound dressings. Among them, hydrogels have been widely used for wound treatment due to their biocompatibility and similarity to the extracellular matrix. The hydrogel formula offers the control of an optimal wound moisture level due to its ability to absorb excess fluid from the wound or release moisture as needed. Additionally, hydrogels can be successfully integrated with a plethora of biologically active components (e.g., nanoparticles, pharmaceuticals, natural extracts, peptides), thus enhancing the performance of resulting composite hydrogels in wound healing applications. In this review, the-state-of-the-art discoveries related to stimuli-responsive hydrogel-based dressings have been summarized, taking into account their antimicrobial, anti-inflammatory, antioxidant, and hemostatic properties, as well as other effects (e.g., re-epithelialization, vascularization, and restoration of the tissue) resulting from their use.

Injectable hydrogels for cartilage and bone tissue regeneration: A review

Annually, millions of patients suffer from irreversible injury owing to the loss or failure of an organ or tissue caused by accident, aging, or disease. The combination of injectable hydrogels and the science of stem cells have emerged to address this persistent issue in society by generating minimally invasive treatments to augment tissue function. Hydrogels are composed of a cross-linked network of polymers that exhibit a high-water retention capacity, thereby mimicking the wet environment of native cells. Due to their inherent mechanical softness, hydrogels can be used as needle-injectable stem cell carrier materials to mend tissue defects. Hydrogels are made of different natural or synthetic polymers, displaying a broad portfolio of eligible properties, which include biocompatibility, low cytotoxicity, shear-thinning properties as well as tunable biological and physicochemical properties. Presently, novel ongoing developments and native-like hydrogels are increasingly being used broadly to improve the quality of life of those with disabling tissue-related diseases. The present review outlines various future and in-vitro applications of injectable hydrogel-based biomaterials, focusing on the newest ongoing developments of in-situ forming injectable hydrogels for bone and cartilage tissue engineering purposes.

Synthesis, Characterization and Biological Properties of Type I Collagen-Chitosan Mixed Hydrogels: A Review

Type I collagen and chitosan are two of the main biological macromolecules used to design scaffolds for tissue engineering. The former has the benefits of being biocompatible and provides biochemical cues for cell adhesion, proliferation and differentiation. However, collagen hydrogels usually exhibit poor mechanical properties and are difficult to functionalize. Chitosan is also often biocompatible, but is much more versatile in terms of structure and chemistry. Although it does have important biological properties, it is not a good substrate for mammalian cells. Combining of these two biomacromolecules is therefore a strategy of choice for the preparation of interesting biomaterials. The aim of this review is to describe the different protocols available to prepare Type I collagen-chitosan hydrogels for the purpose of presenting their physical and chemical properties and highlighting the benefits of mixed hydrogels over single-macromolecule ones. A critical discussion of the literature is provided to point out the poor understanding of chitosan-type I collagen interactions, in particular due to the lack of systematic studies addressing the effect of chitosan characteristics.

Antimicrobial and Osteogenic Effects of Collagen Membrane Decorated with Chitosan-Nano-Hydroxyapatite

Collagen membranes are routinely used in oral surgery for bone regeneration. Despite their numerous advantages, such as stimulating bone growth, bacterial contamination still remains one of the disadvantages of membrane use. Thus, we assessed the biocompatibility and osteogenic and antibacterial properties of a collagen membrane (OsteoBiol) modified with chitosan (CHI) and hydroxyapatite nanoparticles (HApNPs). Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR FT-IR), X-ray powder diffraction (XRD), and field emission scanning electron microscopy (FE-SEM) were performed for membrane characterization. Biocompatibility was assessed on dental pulp stem cells (DPSCs) by an MTT assay, while the osteogenic effect was assessed by an ALP activity assay and qPCR analysis of osteogenic markers (BMP4, ALP, RUNX2, and OCN). Antimicrobial properties were investigated by counting colony-forming units (CFUs) of Streptococcus mitis, Porphyromonas gingivalis, and Fusobaterium nucleatum on membranes and in the surrounding medium. Membranes showed no cytotoxicity. ALP activity was higher and ALP, BMP4, and OCN genes were up-regulated in DPSCs on modified membranes compared to unmodified membranes. The CFUs were reduced on modified membranes and in the medium. Modified membranes showed great biocompatibility and a high osteoinductive effect. Additionally, they showed antimicrobial and antibiofilm effects against periopathogens. It can be concluded that the incorporation of CHI and hydroxyapatite nanoparticles in collagen membranes may be advantageous to promote osteogenesis and reduce bacterial adhesion.

Chitosan-collagen-hydroxyapatite membranes for tissue engineering

Tissue engineering is growing in developing new technologies focused on providing effective solutions to degenerative pathologies that affect different types of connective tissues. The search for biocompatible, bioactive, biodegradable, and multifunctional materials has grown significantly in recent years. Chitosan, calcium phosphates collagen, and their combination as composite materials fulfill the required properties and could result in biostimulation for tissue regeneration. In the present work, the chitosan/collagen/hydroxyapatite membranes were prepared with different concentrations of collagen and hydroxyapatite. Cell adhesion was evaluated by MTS assay for two in vitro models. Additionally, cytotoxicity of the different membranes employing hemolysis of erythrocytes isolated from human blood was carried out. The structure of the membranes was analyzed by X-rays diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal stability properties by thermogravimetric methods (TGA). The highest cell adhesion after 48 h was obtained for chitosan membranes with the highest hydroxyapatite and collagen content. All composite membranes showed good cell adhesion and low cytotoxicity, suggesting that these materials have a significant potential to be used as biomaterials for tissue engineering. Graphical abstract.

Biomedical Application, Patent Repository, Clinical Trial and Regulatory Updates on Hydrogel: An Extensive Review

Hydrogels are known for their leading role in biomaterial systems involving pharmaceuticals that fascinate material scientists to work on the wide variety of biomedical applications. The physical and mechanical properties of hydrogels, along with their biodegradability and biocompatibility characteristics, have made them an attractive and flexible tool with various applications such as imaging, diagnosis and treatment. The water-cherishing nature of hydrogels and their capacity to swell-contingent upon a few ecological signals or the simple presence of water-is alluring for drug conveyance applications. Currently, there are several problems relating to drug delivery, to which hydrogel may provide a possible solution. Hence, it is pertinent to collate updates on hydrogels pertaining to biomedical applications. The primary objective of this review article is to garner information regarding classification, properties, methods of preparations, and of the polymers used with particular emphasis on injectable hydrogels. This review also covers the regulatory and other commerce specific information. Further, it enlists several patents and clinical trials of hydrogels with related indications and offers a consolidated resource for all facets associated with the biomedical hydrogels.

Improvement of Heart Function After Transplantation of Encapsulated Stem Cells Induced with miR-1/Myocd in Myocardial Infarction Model of Rat

Cardiovascular disease is one of the most common causes of death worldwide. Mesenchymal stem cells (MSCs) are one of the most common sources in cell-based therapies in heart regeneration. There are several methods to differentiate MSCs into cardiac-like cells, such as gene induction. Moreover, using a three-dimensional (3D) culture, such as hydrogels increases efficiency of differentiation. In the current study, mouse adipose-derived MSCs were co-transduced with lentiviruses containing microRNA-1 (miR-1) and Myocardin (Myocd). Then, expression of cardiac markers, such as NK2 homeobox 5(Nkx2-5), GATA binding protein 4 (Gata4), and troponin T type 2 (Tnnt2) was investigated, at both gene and protein levels in two-dimensional (2D) culture and chitosan/collagen hydrogel (CS/CO) as a 3D culture. Additionally, after induction of myocardial infarction (MI) in rats, a patch containing the encapsulated induced cardiomyocytes (iCM/P) was implanted to MI zone. Subsequently, 30 days after MI induction, echocardiography, immunohistochemistry staining, and histological examination were performed to evaluate cardiac function. The results of quantitative real -time polymerase chain reaction (qRT-PCR) and immunocytochemistry showed that co-induction of miR-1 and Myocd in MSCs followed by 3D culture of transduced cells increased expression of cardiac markers. Besides, results of in vivo study implicated that heart function was improved in MI model of rats in iCM/P-treated group. The results suggested that miR-1/Myocd induction combined with encapsulation of transduced cells in CS/CO hydrogel increased efficiency of MSCs differentiation into iCMs and could improve heart function in MI model of rats after implantation.

Injectable Hydrogel-Based Nanocomposites for Cardiovascular Diseases

Cardiovascular diseases (CVDs), including a series of pathological disorders, severely affect millions of people all over the world. To address this issue, several potential therapies have been developed for treating CVDs, including injectable hydrogels as a minimally invasive method. However, the utilization of injectable hydrogel is a bit restricted recently owing to some limitations, such as transporting the therapeutic agent more accurately to the target site and prolonging their retention locally. This review focuses on the advances in injectable hydrogels for CVD, detailing the types of injectable hydrogels (natural or synthetic), especially that complexed with stem cells, cytokines, nano-chemical particles, exosomes, genetic material including DNA or RNA, etc. Moreover, we summarized the mainly prominent mechanism, based on which injectable hydrogel present excellent treating effect of cardiovascular repair. All in all, it is hopefully that injectable hydrogel-based nanocomposites would be a potential candidate through cardiac repair in CVDs treatment.

An Overview of Injectable Thermo-Responsive Hydrogels and Advances in their Biomedical Applications

BACKGROUND

Injectable hydrogels are a thermo-responsive system based on biomaterials. Injectable hydrogels have been broadly investigated mainly as vehicles or scaffolds of therapeutic agents that include drugs, proteins, cells, and bioactive molecules among others, utilized in the treatment of diseases such as cancers and the repair and regeneration of tissues.

RESULTS

There are several studies that have described the multiple features of hydrogels. However, the main aspect that breaks the paradigm in the application of hydrogels is the thermoresponsiveness that some of them have, which is an abrupt modification in their properties in response to small variations in temperature. For that reason, the thermo-responsive hydrogels with the unique property of sol-gel transition have received special attention over the past decades. These hydrogels show phase transition near physiological human body temperature. This feature is key for being applied in promising areas of human health-related research.

CONCLUSION

The purpose of this study is the overview of injectable hydrogels and their latest advances in medical applications including bioactive compound delivery, tissue engineering, and regenerative medicine.

Effect of Collagen-Chitosan-Glycerol Composition in Scaffold for Gingival Recession Therapy

The case of gingival recession has a high prevalence, about 88% of the population of the United States in one or more locations suffering from gingival recession. One of the handling cases of gingival recession is to use scaffold that includes the development of tissue and cell engineering. This study aims to determine the best composition variation scaffold of collagen-chitosan with the addition of glycerol. The process of synthesis of collagen-chitosan-glycerol scaffold using freeze dry method that can form pores on the scaffold. Characterization was also carried out on the results of the synthesis of collagen-chitosan scaffold with the addition of glycerol include the morphological characterization, tensile, cytotoxicity, swelling, degradation, and thickness. The results of morphological characterization showed pore size ranged from 26.68 - 191.7 μm with a thickness of 0.51 - 0.65 mm which was suitable for handling of gingival recession cases. The result of tensile test showed that the variation of 9: 1 has the lowest value that is 2.87 MPa where the value is close to tensile strength value for periodontal which has a value ranging from 2.75 to 5.13. The characterization of cytotoxicity shows a value that is less in line with the literature, where live cells <50%. This is because collagen and chitosan have an acidic pH so that the cells cannot reproduce. Characterization of degradation shows all the variations experienced a severe reduction process from day to day. The characterization of the swelling of all samples was equilibrated at 7 minute. Chitosan-collagen scaffold with the addition of glycerol has good potential as a scaffold candidate for gingival recession therapy based on morphological characterization (thickness and surface structure), the mechanical strength (tensile strength), degradation, and the degree of swelling.