Injectable graphene oxide/hydrogel-based angiogenic gene delivery system for vasculogenesis and cardiac repair

Functionalization and optimization-strategy of graphene oxide-based nanomaterials for gene and drug delivery

Graphene-family nanomaterials (GFNs) have been widely used in cancer therapy, tissue engineering, antibacterial and biological imaging due to their optical, thermal, and drug absorption properties. When used as drug and gene nanocarrier, the major limitations are aggregation, biocompatibility, and inappropriate release of drugs or genes. To overcome these problems, researchers have developed a variety of functionalization processes. In this review, we grouped the functionalization according to the decoration molecules, putting particular emphasis on the gene delivery. Organic and inorganic materials resulted as the major sets to introduce functional sections onto graphene oxide (GO). We also classified the target molecules used in the GO delivery system, as well as introduced other strategies to increase the delivery efficacy such as controlled release and magnetic targeting.

Graphene Oxide Loaded Hydrogel for Enhanced Wound Healing in Diabetic Patients

Chronic wound or slow healing of a wound is one of the serious complications in diabetic patients. The decrease in the proliferation and migration of cells such as keratinocytes and fibroblasts is the major reason for the development of such chronic wounds in a diabetic patient. Therefore, designing a wound dressing patch using a biodegradable hydrogel, which can provide a sustained release/delivery of active agents that can support cell proliferation and cell migration, will be highly beneficial for promoting diabetic wound healing. Multiple evidences from both in-vitro and in-vivo studies have shown that graphene oxide (GO) and reduced graphene oxide promote wound healing by promoting migration and proliferation of keratinocyte cells. In addition, GO possesses angiogenic property. Gelatin methacrylate (GelMA) based hydrogels display excellent hydrophilic properties due to the presence of hydrophilic amino, amido, carboxyl, and hydroxyl groups in the polymer chains, which gives them highly porous, soft and flexible structure. In this work, we report the development of hydrogel dressing incorporated with GO to improve wound healing by increasing the proliferation and migration of cells.

Reactive Nitrogen Species Releasing Hydrogel for Enhanced Wound Healing

Poor proliferation and migration of fibroblast, keratinocyte and endothelial cells delays the wound healing in diabetic patients and results into chronicity of wounds. Slow or decreased formation of blood vessels is another issue that increases the chronicity of non-healing wounds. These chronic wounds turn into an ulcer that may lead to limb amputation. Recently, nitric oxide (NO) has emerged as a potential agent for accelerating cell migration and proliferation to enhance wound healing. It increases the expression of necessary angiogenic growth factors which stimulates the proliferation and migration of major cell types involved in wound repair. Here we report the synthesis of chitosan (CS), polyvinyl alcohol (PVA) and a NO donor S-nitroso-N-acetyl-DL-penicillamine (SNAP) to enhance the wound healing activities in chronic wounds. A three-fold increase in the proliferation of 3T3 cells was observed with NO-releasing CS-PVA hydrogels. In vitro cell migration assay demonstrated a four-fold faster migration of cells to the scratched area compared to the control group. The results depict that the use of CS-PVA hydrogel impregnated with the NO donor (SNAP) can be a promising material for promoting cell migration and subsequent accelerated healing of the chronic wounds in burns and diabetic patients.

Poly(N-isopropylacrylamide)-based dual-crosslinking biohybrid injectable hydrogels for vascularization

Injectable hydrogels provide a powerful and non-invasive approach for numerous applications in cell transplantation, growth factor delivery, tissue regeneration and so forth. The properties of injectable hydrogels should be well-tuned for specific applications, where their overall design should ensure biocompatibility, non-toxicity, robust mechanical properties, and most importantly the ability to promote vascularization and integration with the host tissue/organ. Among these criteria, vascularization remains a key design element in the development of functional therapeutic hydrogels for successful translation into clinical settings. To that end, there is still a critical need for the development of the next generation of injectable hydrogels with precisely tuned biophysical and biochemical properties which could simultaneously promote tissue vascularization. In this work, we developed a temperature responsive, dual-crosslinking, biohybrid hydrogels, modified with a vasculogenic peptide for applications in regenerative medicine, specifically tissue vascularization. The synthesized hydrogels consisted of poly(N-isopropylacrylamide)-based copolymer, functionalized gelation and angiogenic VEGF-mimetic QK peptide with enhanced shear-thinning and injectability properties. QK peptide is a VEGF-mimetic vasculogenic peptide which binds to VEGF receptors and activates intercellular pathway for vascularization. Apart from the presence of QK peptide, the mechanical properties of the hydrogels were precisely tuned by altering the polymer concentration, enabling successful assembly and endothelial cell network formation. Extended in vitro studies demonstrated successful encapsulation and homogeneous distribution of endothelial cells within the three-dimensional (3D) environment of the hydrogel matrix with significantly enhanced vascularization in presence of the QK peptide as early as 3 days of culture. A small, preliminary in vivo study in mice showed a trend of increased blood vessel formation in hydrogels that incorporated the QK peptide. Overall, our study presents the design and characterization of injectable, dual-crosslinking and vasculogenic hydrogels with controlled properties which could be utilized for numerous applications in regenerative medicine, minimally invasive cell and drug delivery as well as fundamental studies on tissue vascularization and angiogenesis. STATEMENT OF SIGNIFICANCE: In this work, we synthesized a new class of temperature responsive, dual-crosslinking, biohybrid injectable hydrogels with enhanced vascularization properties for broad applications in regenerative medicine and minimally invasive cell/drug delivery. The developed hydrogels properly accommodated 3D culture, assembly and network formation of endothelial cells, as evidenced by in vitro and in vivo studies.

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.

Current Use of Carbon-Based Materials for Biomedical Applications—A Prospective and Review

Among a large number of current biomedical applications in the use of medical devices, carbon-based nanomaterials such as graphene (G), graphene oxides (GO), reduced graphene oxide (rGO), and carbon nanotube (CNT) are frontline materials that are suitable for developing medical devices. Carbon Based Nanomaterials (CBNs) are becoming promising materials due to the existence of both inorganic semiconducting properties and organic π-π stacking characteristics. Hence, it could effectively simultaneously interact with biomolecules and response to the light. By taking advantage of such aspects in a single entity, CBNs could be used for developing biomedical applications in the future. The recent studies in developing carbon-based nanomaterials and its applications in targeting drug delivery, cancer therapy, and biosensors. The development of conjugated and modified carbon-based nanomaterials contributes to positive outcomes in various therapies and achieved emerging challenges in preclinical biomedical applications. Subsequently, diverse biomedical applications of carbon nanotube were also deliberately discussed in the light of various therapeutic advantages.

Management of Myocarditis-Related Cardiomyopathy in Adults

Myocarditis is generally a mild and self-limited consequence of systemic infection of cardiotropic viruses. However, patients can develop a temporary or permanent impairment of cardiac function including acute cardiomyopathy with hemodynamic compromise or severe arrhythmias. In this setting, specific causes of inflammation are associated with variable risks of death and transplantation. Recent translational studies suggest that treatments tailored to specific causes of myocarditis may impact clinical outcomes when added to guideline-directed medical care. This review summarizes recent advances in translational research that influence the utility of endomyocardial biopsy for the management of inflammatory cardiomyopathies. Emerging therapies for myocarditis based on these mechanistic hypotheses are entering clinical trials and may add to the benefits of established heart failure treatment.

Mussel-inspired conductive Ti2C-cryogel promotes functional maturation of cardiomyocytes and enhances repair of myocardial infarction

Rationale: Researches on conductive engineering cardiac patch (ECP) for myocardial infarction (MI) treatment have achieved some progress in the animal while the availability of traditional conductive materials in ECP is still limited because of their controversial cytotoxicity. Here we aim to introduce a novel hydrophilic biocompatible conductive material: MXene Ti₂C and mussel-inspired dopamine into PEGDA-GelMA cryogel to construct a bio-functional ECP of which the property closes to natural heart for the repair of MI.

Method: MXene Ti₂C was etched from MAX Ti₂AlC, then uniformly dispersed into the prepolymer composed with dopamine-N′, N′-methylene-bisacrylamide, methacrylate-gelatin, and poly (ethylene glycol) diacrylate by simple water bath sonication. The resilient conductive Ti₂C-cryogel was fabricated by chemical cryogelation. The conductive ECP was evaluated in vitro and transplanted to the MI rat model for MI treatment.

Results: In vitro, the 3D vessels-shape framework was observed in Ti₂C-8-cryogel which was seeded with rats aortic endothelial cells. When the Ti₂C-cryogels were cocultured with CMs, remarkably aligned sarcomere and the primitive intercalated disc between the mature CMs were formed on day 7. The as-prepared Ti₂C-8-cryogel ECP also demonstrated rapid calcium transients and synchronous tissue-like beating. When transplanted into the infarcted heart of the MI rat model, the Ti₂C-8-cryogel ECP could improve the cardiac function, reduce the infarct size, and inhibit the inflammatory response. Obvious vasculation especially newly formed arteriole was also found.

Conclusion: A novel conductive Ti₂C-embedded cardiac patch with suitable conductivity and the mechanical property was developed and could be served as an ideal candidate for MI repair.

Insights into the angiogenic effects of nanomaterials: mechanisms involved and potential applications

The vascular system, which transports oxygen and nutrients, plays an important role in wound healing, cardiovascular disease treatment and bone tissue engineering. Angiogenesis is a complex and delicate regulatory process. Vascular cells, the extracellular matrix (ECM) and angiogenic factors are indispensable in the promotion of lumen formation and vascular maturation to support blood flow. However, the addition of growth factors or proteins involved in proangiogenic effects is not effective for regulating angiogenesis in different microenvironments. The construction of biomaterial scaffolds to achieve optimal growth conditions and earlier vascularization is undoubtedly one of the most important considerations and major challenges among engineering strategies. Nanomaterials have attracted much attention in biomedical applications due to their structure and unique photoelectric and catalytic properties. Nanomaterials not only serve as carriers that effectively deliver factors such as angiogenesis-related proteins and mRNA but also simulate the nano-topological structure of the primary ECM of blood vessels and stimulate the gene expression of angiogenic effects facilitating angiogenesis. Therefore, the introduction of nanomaterials to promote angiogenesis is a great helpful to the success of tissue regeneration and some ischaemic diseases. This review focuses on the angiogenic effects of nanoscaffolds in different types of tissue regeneration and discusses the influencing factors as well as possible related mechanisms of nanomaterials in endothelial neovascularization. It contributes novel insights into the design and development of novel nanomaterials for vascularization and therapeutic applications.

Functional DNA-based hydrogel intelligent materials for biomedical applications

Multifunctional intelligent DNA hydrogels have been reviewed for many biomedical applications.

High-Strength, Self-Healable, Temperature-Sensitive, MXene-Containing Composite Hydrogel as a Smart Compression Sensor

As a new two-dimensional material similar to graphene, MXene has attracted extensive attention in the field of electrochemical materials such as supercapacitors because of its excellent mechanical properties, electrical conductivity, and thermal conductivity. What is better than graphene is that the few-layer MXene material obtained by proper treatment has good water dispersibility and can be used as an ideal nanomaterial to enhance the conductivity of hydrogels. However, the articles about the few-layer MXene material used in the preparation of composite hydrogels are rare. In this paper, MXene was synthesized by Yury mild method. Poly(N-isopropyl acrylamide) (PNIPAM) hydrogel and physical cross-linking hydrogel were used as the matrix to prepare composite hydrogels with temperature sensitivity and stress-sensing properties. The composite hydrogels exhibited excellent mechanical properties: it could be stretched to over 14 times the original length and achieved a 0.4 MPa tensile strength while showing good self-healing ability, which was of great significance for the practical application of hydrogels. The conductivity of the composite hydrogel was 1.092 S/m, which was about 15 times that of the control hydrogel without MXene. The potential of the composite hydrogel as a smart compression sensor was also verified by the conductivity tests.

Reduced Graphene Oxide Incorporated GelMA Hydrogel Promotes Angiogenesis For Wound Healing Applications

PURPOSE

Non-healing or slow healing chronic wounds are among serious complications of diabetes that eventually result in amputation of limbs and increased morbidities and mortalities. Chronic diabetic wounds show reduced blood vessel formation (lack of angiogenesis), inadequate cell proliferation and poor cell migration near wounds. In this paper, we report the development of a hydrogel-based novel wound dressing material loaded with reduced graphene oxide (rGO) to promote cell proliferation, cell migration and angiogenesis for wound healing applications.

METHODS

Gelatin-methacryloyl (GelMA) based hydrogels loaded with different concentrations of rGO were fabricated by UV crosslinking. Morphological and physical characterizations (porosity, degradation, and swelling) of rGO incorporated GelMA hydrogel was performed. In vitro cell proliferation, cell viability and cell migration potential of the hydrogels were analyzed by MTT assay, live/dead staining, and wound healing scratch assay respectively. Finally, in vivo chicken embryo angiogenesis (CEO) testing was performed to evaluate the angiogenic potential of the prepared hydrogel.

RESULTS

The experimental results showed that the developed hydrogel possessed enough porosity and exudate-absorbing capacity. The biocompatibility of prepared hydrogel on three different cell lines (3T3 fibroblasts, EA.hy926 endothelial cells, and HaCaT keratinocytes) was confirmed by in vitro cell culture studies (live/dead assay). The GelMA hydrogel containing 0.002% w/w rGO considerably increased the proliferation and migration of cells as evident from MTT assay and wound healing scratch assay. Furthermore, rGO impregnated GelMA hydrogel significantly enhanced the angiogenesis in the chick embryo model.

CONCLUSION

The positive effect of 0.002% w/w rGO impregnated GelMA hydrogels on angiogenesis, cell migration and cell proliferation suggests that these formulations could be used as a functional wound healing material for the healing of chronic wounds.

The rationale and emergence of electroconductive biomaterial scaffolds in cardiac tissue engineering

The human heart possesses minimal regenerative potential, which can often lead to chronic heart failure following myocardial infarction. Despite the successes of assistive support devices and pharmacological therapies, only a whole heart transplantation can sufficiently address heart failure. Engineered scaffolds, implantable patches, and injectable hydrogels are among the most promising solutions to restore cardiac function and coax regeneration; however, current biomaterials have yet to achieve ideal tissue regeneration and adequate integration due a mismatch of material physicochemical properties. Conductive fillers such as graphene, carbon nanotubes, metallic nanoparticles, and MXenes and conjugated polymers such as polyaniline, polypyrrole, and poly(3,4-ethylendioxythiophene) can possibly achieve optimal electrical conductivities for cardiac applications with appropriate suitability for tissue engineering approaches. Many studies have focused on the use of these materials in multiple fields, with promising effects on the regeneration of electrically active biological tissues such as orthopedic, neural, and cardiac tissue. In this review, we critically discuss the role of heart electrophysiology and the rationale toward the use of electroconductive biomaterials for cardiac tissue engineering. We present the emerging applications of these smart materials to create supportive platforms and discuss the crucial role that electrical stimulation has been shown to exert in maturation of cardiac progenitor cells.

Decellularized Annulus Fibrosus Matrix/Chitosan Hybrid Hydrogels with Basic Fibroblast Growth Factor for Annulus Fibrosus Tissue Engineering

Low back pain caused by degenerative disc disease affects many people worldwide and brings huge economical burden. Thus, attentions have focused on annulus fibrosus (AF) tissue engineering for treatment of intervertebral disc degeneration. To engineer a functional replacement for the AF, it is important to fabricate scaffolds that mimic the structural and mechanical properties of native tissue. AF-derived stem cells are promising seed cells for AF tissue engineering due to their tissue specificity. In the present study, decellularized AF matrix (DAFM)/chitosan hybrid hydrogels were fabricated using genipin as a crosslinker. AF stem cells were cultured on hydrogel scaffolds with or without basic fibroblast growth factor (bFGF), and cell proliferation, morphology, gene expression, and AF tissue synthesis were examined. Overall, more collagen-I, collagen-II, and aggrecan were secreted by AF stem cells grown on hydrogels with bFGF compared to those without. These results support the application of DAFM/chitosan hybrid hydrogels as an appropriate candidate for AF tissue engineering. Furthermore, incorporation of bFGF into hydrogels promoted AF-related tissue synthesis.

Nanoscale Technologies for Prevention and Treatment of Heart Failure: Challenges and Opportunities

The adult myocardium has a limited regenerative capacity following heart injury, and the lost cells are primarily replaced by fibrotic scar tissue. Suboptimal efficiency of current clinical therapies to resurrect the infarcted heart results in injured heart enlargement and remodeling to maintain its physiological functions. These remodeling processes ultimately leads to ischemic cardiomyopathy and heart failure (HF). Recent therapeutic approaches (e.g., regenerative and nanomedicine) have shown promise to prevent HF postmyocardial infarction in animal models. However, these preclinical, clinical, and technological advancements have yet to yield substantial enhancements in the survival rate and quality of life of patients with severe ischemic injuries. This could be attributed largely to the considerable gap in knowledge between clinicians and nanobioengineers. Development of highly effective cardiac regenerative therapies requires connecting and coordinating multiple fields, including cardiology, cellular and molecular biology, biochemistry and chemistry, and mechanical and materials sciences, among others. This review is particularly intended to bridge the knowledge gap between cardiologists and regenerative nanomedicine experts. Establishing this multidisciplinary knowledge base may help pave the way for developing novel, safer, and more effective approaches that will enable the medical community to reduce morbidity and mortality in HF patients.

Thermo-sensitive hydrogels for delivering biotherapeutic molecules: A review

To date, a variety of delivery systems based on organic or inorganic materials have been investigated. Among them, hydrogels have become one of the most promising field in drug delivery system due to their unique properties. Temperature-sensitive hydrogels, which gelation at physiological temperature, gift the delivery system with excellent spatial and temporal control, and have a widely application in drug delivery, tissue engineering, imaging, and wound dressing. This review provides a brief overview on the concept and classification of temperature-sensitive hydrogels, and covers the application of temperature-sensitive gel systems in delivery of biotherapeutic molecules.

Injectable Citrate-Based Hydrogel as an Angiogenic Biomaterial Improves Cardiac Repair after Myocardial Infarction

Implanted medical biomaterials are closely in contact with host biological systems via biomaterial-cell/tissue interactions, and these interactions play pivotal roles in regulating cell functions and tissue regeneration. However, many biomaterials degrade over time, and these degradation products also have been shown to interact with host cells/tissue. Therefore, it may prove useful to specifically design implanted biomaterials with degradation products which greatly improve the performance of the implant. Herein, we report an injectable, citrate-containing polyester hydrogel which can release citrate as a cell regulator via hydrogel degradation and simultaneously show sustained release of an encapsulated growth factor Mydgf. By coupling the therapeutic effect of the hydrogel degradation product (citrate) with encapsulated Mydgf, we observed improved postmyocardial infarction (MI) heart repair in a rat MI model. Intramyocardial injection of our Mydgf-loaded citrate-containing hydrogel was shown to significantly reduce scar formation and infarct size, increase wall thickness and neovascularization, and improve heart function. This bioactive injectable hydrogel-mediated combinatorial approach offers myriad advantages including potential adjustment of delivery rate and duration, improved therapeutic effect, and minimally invasive administration. Our rational design combining beneficial degradation product and controlled release of therapeutics provides inspiration toward the next generation of biomaterials aiming to revolutionize regenerative medicine.

Well-Optimized Conjugated GO-DNA Nanosystem for Sensitive Ratiometric pH Detection in Live Cells

Intracellular pH is a vital parameter which can reflect the physiological process, and the detection of intracellular pH with a high signal-to-noise ratio (SNR) remains a challenge. Compared to pH biosensors based on a single-wavelength signal, it is much easier to obtain better sensitivity and higher SNR from the biosensors by two-wavelength ratiometric signals. In this study, we used DNA-grafted graphene oxide (GO) to ratiometrically detect intracellular pH ranging from basic to acidic. A high SNR with a 35-fold difference in the ratiometric output has been achieved through careful optimization: (1) A high DNA conjugation yield of 45% has been gained through utilizing the partial double-stranded assembly strategy. (2) Herring sperm DNA (HSD) plays an important role in improving the sensitivity of the nanosystem by purifying and passivating the surface of GO; therefore, the concentration of HSD has been optimized to pursue the most sensitive ratiometric response. Apart from the ultrahigh SNR, fabricated GO-AR-Cy5/IFO-Cy3 exhibited excellent stability and biocompatibility in biological environments. Further experiments demonstrated that the nanosystem worked well in live cells in response to pH changes. It is possible to distinguish small pH differences and realize quantitative detection based on ratiometric fluorescence imaging by laser scanning confocal microscope analysis, which makes the nanosystem a promising candidate for further biological study and clinical applications.

Graphene oxide: A growth factor delivery carrier to enhance chondrogenic differentiation of human mesenchymal stem cells in 3D hydrogels

Cartilage engineering with stem cells in 3D scaffolds is a promising future therapy to treat cartilage defects. One challenge in the field is to design carriers to efficaciously deliver biological factors in 3D scaffolds containing stem cells to appropriately guide differentiation of these cells in same scaffolds and promote specific tissue synthesis. Graphene-based 2D nanomaterials have recently attracted extensive interest for their biomedical applications as they can adsorb a plethora of biological molecules, thus offering high potential as delivery carriers. This study utilized graphene oxide (GO) flakes to adsorb transforming growth factor β3 (TGF-β3), which were then incorporated into a collagen hydrogel. Human mesenchymal stem cells (hMSCs) were encapsulated in the same gel and chondrogenic differentiation assessed. The study showed GO flakes adsorbed > 99% TGF-β3 with <1.7% release. Adsorbed TGF-β3 retained a similar conformation to its dissolved counterpart (free protein) but importantly demonstrated greater conformational stability. Smad2 phosphorylation was promoted, and higher chondrogenic gene expression and cartilage-specific extracellular matrix deposition were achieved compared to exogenously delivering TGF-β3 in culture media. Effects were sustained in long-term 28-day culture. The results demonstrate GO flakes as highly-efficient for delivering GFs in 3D to guide cells in the same scaffold and induce tissue formation. The ability of GO flakes to provide sustained local delivery makes this material attractive for tissue engineering strategies, in particular for regionally-specific MSC differentiation (e.g. osteochondral tissue engineering). STATEMENT OF SIGNIFICANCE: Cartilage engineering involving stem cells in 3D scaffolds is a promising future therapy to treat cartilage defects which can lead to debilitating conditions such as osteoarthritis. However, this field faces the challenge to design delivery carriers to efficaciously deliver biological factors inside these 3D cell-containing scaffolds for appropriately-guided cell differentiation. Graphene-based 2D nanomaterials offer high potential as delivery carriers, but to date studies using them to deliver biological factors have been restricted to 2D substrates, non-scaffold cell masses, or acellular 3D scaffolds. Our study for the first time demonstrated simultaneously incorporating both human mesenchymal stem cells (hMSCs) and GO (graphene oxide)-adsorbed growth factor TGFβ3 into a 3D scaffold, where GO-adsorbed TGFβ3 enhanced chondrogenic differentiation of hMSCs and cartilage-tissue synthesis throughout the scaffold without needing to repeatedly supply TGFβ3 exogenously.

Injectable Catalyst-Free Poly(Propylene Fumarate) System Cross-Linked by Strain Promoted Alkyne-Azide Cycloaddition Click Chemistry for Spine Defect Filling

A new PPF-BCN/hyPCL32-N3 injectable system that can be cross-linked by catalyst-free, strain promoted alkyne-azide cycloaddition (SPAAC) click chemistry was developed for tissue engineering applications. The system consisted of two components: PPF-BCN, poly(propylene fumarate) (PPF) functionalized with (1R,8S,9s)-bicyclo[6.1.0]non-4-yn-9-ylmethanol (BCN-OH), and hyPCL32-N3, a hyper-branched 32-arm poly(ε-caprolactone) (PCL) dendrimer functionalized with azide as the cross-linker core. Fast SPAAC click reaction allowed the desired gelation of the system without using any toxic initiator or catalyst. Compared to the conventional injectable formulation, e.g., poly(methyl methacrylate) (PMMA), our PPF-BCN/hyPCL32-N3 (abbreviated as PFCL-Click) injectable system showed enhanced biocompatibility and low heat generation during cross-linking. After reaction, the cross-linked PFCL-Click scaffolds supported excellent proliferation and differentiation of preosteoblast cells on the surface. The PFCL-Click system can be successfully injected into vertebral bodies of rabbit spine and can be monitored by X-ray imaging after incorporating zirconium dioxide (ZrO2) powder. With these unique advantages, this injectable system has promising potential for bone defect repair and other tissue engineering and regenerative medicine applications.

Self-Healing Hydrogels: The Next Paradigm Shift in Tissue Engineering?

Given their durability and long-term stability, self-healable hydrogels have, in the past few years, emerged as promising replacements for the many brittle hydrogels currently being used in preclinical or clinical trials. To this end, the incompatibility between hydrogel toughness and rapid self-healing remains unaddressed, and therefore most of the self-healable hydrogels still face serious challenges within the dynamic and mechanically demanding environment of human organs/tissues. Furthermore, depending on the target tissue, the self-healing hydrogels must comply with a wide range of properties including electrical, biological, and mechanical. Notably, the incorporation of nanomaterials into double-network hydrogels is showing great promise as a feasible way to generate self-healable hydrogels with the above-mentioned attributes. Here, the recent progress in the development of multifunctional and self-healable hydrogels for various tissue engineering applications is discussed in detail. Their potential applications within the rapidly expanding areas of bioelectronic hydrogels, cyborganics, and soft robotics are further highlighted.

Design of Nanocomposite Injectable Hydrogels for Minimally Invasive Surgery

Biocompatible hydrogels are materials that hold great promise in medicine and biology since the porous structure, the ability to entrap a large amount of water, and the tunability of their mechanical and tissue adhesive properties make them suitable for several applications, including wound healing, drug and cell delivery, cancer treatment, bioelectronics, and tissue regeneration. Among the possible developed systems, injectable hydrogels, owing to their properties, are optimal candidates for in vivo minimally invasive procedures. To be injectable, a hydrogel must be liquid before and during the injection, but it must quickly jellify after injection to form a soft, self-standing, solid material. The possibility to work with a liquid precursor encoding the functions that will be available after gelation allows the development of biocompatible materials that can be employed in surgery and, in particular, in noninvasive procedures. The underlying idea is to reach the target tissue by using just a needle, or by exploiting the natural body orifices, reducing surgery procedure time, induced pain, and risk of infections. Hydrogels with different properties can be obtained by changing the type of cross-linking, the cross-linking density or the molecular weight of the polymer, or by introducing pending functional groups. The introduction of a nanofiller in the hydrogel network allows for expanding the suite of the structural and functional properties and for better mimicking native tissues. In this Account, we discuss how to provide a hydrogel network with designed properties by playing with both the polymeric chains and the fillers. We present selected examples from the literature that show how to introduce stiffness, stretchability, adhesiveness, self-healing, anisotropy, antimicrobial activity, biodegradability, and conductivity in injectable hydrogels. We further describe how the chemical composition, the mechanical properties, and the microarchitecture of the hydrogel influence cell adhesion, proliferation, and differentiation. Examples of injectable hydrogels for innovative minimally invasive procedures are then discussed in detail; in particular, we showcase the use of hydrogels for tumor resection and as vascular chemoembolization agents. We further discuss how one can improve the rheological properties of injectable hydrogels to exploit them in osteochondral tissue engineering. The effect of the introduction of a conductive filler is then presented in relation to the development of electroactive scaffolds for cardiac-tissue engineering and neural and nerve repair. We believe that the rational design of biocompatible, injectable hybrid hydrogels with tunable properties will likely play a crucial role in reducing the invasiveness and improving the outcome of several clinical and surgical setups.

Inhibition of Senescence-Associated Genes Rb1 and Meis2 in Adult Cardiomyocytes Results in Cell Cycle Reentry and Cardiac Repair Post-Myocardial Infarction

Background Myocardial infarction results in a large-scale cardiomyocyte loss and heart failure due to subsequent pathological remodeling. Whereas zebrafish and neonatal mice have evident cardiomyocyte expansion following injury, adult mammalian cardiomyocytes are principally nonproliferative. Despite historical presumptions of stem cell-mediated cardiac regeneration, numerous recent studies using advanced lineage-tracing methods demonstrated that the only source of cardiomyocyte renewal originates from the extant myocardium; thus, the augmented proliferation of preexisting adult cardiomyocytes remains a leading therapeutic approach toward cardiac regeneration. In the present study we investigate the significance of suppressing cell cycle inhibitors Rb1 and Meis2 to promote adult cardiomyocyte reentry to the cell cycle. Methods and Results In vitro experiments with small interfering RNA-mediated simultaneous knockdown of Rb1 and Meis2 in both adult rat cardiomyocytes, isolated from 12-week-old Fischer rats, and human induced pluripotent stem cell-derived cardiomyocytes showed a significant increase in cell number, a decrease in cell size, and an increase in mononucleated cardiomyocytes. In vivo, a hydrogel-based delivery method for small interfering RNA-mediated silencing of Rb1 and Meis2 is utilized following myocardial infarction. Immunofluorescent imaging analysis revealed a significant increase in proliferation markers 5-ethynyl-2'-deoxyuridine, PH3, KI67, and Aurora B in adult cardiomyocytes as well as improved cell survivability with the additional benefit of enhanced peri-infarct angiogenesis. Together, this intervention resulted in a reduced infarct size and improved cardiac function post-myocardial infarction. Conclusions Silencing of senescence-inducing pathways in adult cardiomyocytes via inhibition of Rb1 and Meis2 results in marked cardiomyocyte proliferation and increased protection of cardiac function in the setting of ischemic injury.

Application of Ti3 C2 MXene Quantum Dots for Immunomodulation and Regenerative Medicine

Inflammation is tightly linked to tissue injury. In regenerative medicine, immune activation plays a key role in rejection of transplanted stem cells and reduces the efficacy of stem cell therapies. Next-generation smart biomaterials are reported to possess multiple biologic properties for tissue repair. Here, the first use of 0D titanium carbide (Ti₃ C₂ ) MXene quantum dots (MQDs) for immunomodulation is presented with the goal of enhancing material-based tissue repair after injury. MQDs possess intrinsic immunomodulatory properties and selectively reduce activation of human CD4⁺ IFN-γ⁺ T-lymphocytes (control 87.1 ± 2.0%, MQDs 68.3 ± 5.4%) while promoting expansion of immunosuppressive CD4⁺ CD25⁺ FoxP3⁺ regulatory T-cells (control 5.5 ± 0.7%, MQDs 8.5 ± 0.8%) in a stimulated lymphocyte population. Furthermore, MQDs are biocompatible with bone marrow-derived mesenchymal stem cells and induced pluripotent stem cell-derived fibroblasts. Finally, Ti₃ C₂ MQDs are incorporated into a chitosan-based hydrogel to create a 3D platform with enhanced physicochemical properties for stem cell delivery and tissue repair. This composite hydrogel demonstrates increased conductivity while maintaining injectability and thermosensitivity. These findings suggest that this new class of biomaterials may help bridge the translational gap in material and stem cell-based therapies for tissue repair and treatment of inflammatory and degenerative diseases.

Graphene-based 3D scaffolds in tissue engineering: fabrication, applications, and future scope in liver tissue engineering

Tissue engineering embraces the potential of recreating and replacing defective body parts by advancements in the medical field. Being a biocompatible nanomaterial with outstanding physical, chemical, optical, and biological properties, graphene-based materials were successfully employed in creating the perfect scaffold for a range of organs, starting from the skin through to the brain. Investigations on 2D and 3D tissue culture scaffolds incorporated with graphene or its derivatives have revealed the capability of this carbon material in mimicking in vivo environment. The porous morphology, great surface area, selective permeability of gases, excellent mechanical strength, good thermal and electrical conductivity, good optical properties, and biodegradability enable graphene materials to be the best component for scaffold engineering. Along with the apt microenvironment, this material was found to be efficient in differentiating stem cells into specific cell types. Furthermore, the scope of graphene nanomaterials in liver tissue engineering as a promising biomaterial is also discussed. This review critically looks into the unlimited potential of graphene-based nanomaterials in future tissue engineering and regenerative therapy.

Cerium Oxide Nanoparticle Incorporated Electrospun Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Membranes for Diabetic Wound Healing Applications

Insufficient cell proliferation, cell migration, and angiogenesis are among the major causes for nonhealing of chronic diabetic wounds. Incorporation of cerium oxide nanoparticles (nCeO₂) in wound dressings can be a promising approach to promote angiogenesis and healing of diabetic wounds. In this paper, we report the development of a novel nCeO₂ containing electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) membrane for diabetic wound healing applications. In vitro cell adhesion studies, chicken embryo angiogenesis assay, and in vivo diabetic wound healing studies were performed to assess the cell proliferation, angiogenesis, and wound healing potential of the developed membranes. The experimental results showed that nCeO₂ containing PHBV membranes can promote cell proliferation and cell adhesion when used as wound dressings. For less than 1% w/w of nCeO₂ content, human mammary epithelial cells (HMEC) were adhered parallel to the individual fibers of PHBV. For higher than 1% w/w of nCeO₂ content, cells started to flatten and spread over the fibers. In ovo angiogenic assay showed the ability of nCeO₂ incorporated PHBV membranes to enhance blood vessel formation. In vivo wound healing study in diabetic rats confirmed the wound healing potential of nCeO₂ incorporated PHBV membranes. The study suggests that nCeO₂ incorporated PHBV membranes have strong potential to be used as wound dressings to enhance cell proliferation and vascularization and promote the healing of diabetic wounds.

Injectable Nanocomposite Hydrogels and Electrosprayed Nano(Micro)Particles for Biomedical Applications

Polymeric scaffolds have played important roles in biomedical applications due to their potentially practical performance such as delivery of bioactive components and/or regenerative cells. These materials were well-designed to encapsulate bioactive molecules or/and nanoparticles for enhancing their performance in tissue regeneration and drug delivery systems. In the study, several multifunctional nanocomposite hydrogel and polymeric nano(micro)particles-electrosprayed platforms were described from their fabrication methods and structural characterizations to potential applications in the mentioned fields. Regarding to their described performance, these multifunctional nanocomposite biomaterials could pay many ways for further studies that enables them apply in clinical applications.

Hybrid hydrogels for biomedical applications

The use of hydrogels in biomedical applications dates back multiple decades, and the engineering potential of these materials continues to grow with discoveries in chemistry and biology. The approaches have led to increasing complex hydrogels that incorporate both synthetic and natural polymers and functional domains for tunable release kinetics, mediated cell response, and ultimately use in clinical and research applications in biomedical practice. This review focuses on recent advances in hybrid hydrogels that incorporate nano/microstructures, their synthesis, and applications in biomedical research. Examples discussed include the implementation of click reactions, photopatterning, and 3D printing for the facile production of these hybrid hydrogels, the use of biological molecules and motifs to promote a desired cellular outcome, and the tailoring of kinetic and transport behavior through hybrid-hydrogel engineering to achieve desired biomedical outcomes. Recent progress in the field has established promising approaches for the development of biologically relevant hybrid hydrogel materials with potential applications in drug discovery, drug/gene delivery, and regenerative medicine.

Amyloid-Based Injectable Hydrogel Derived from Hydrolyzed Hen Egg White Lysozyme

Injectable hydrogels based on synthetic peptides have shown great promise in many biomedical applications. Yet, the high cost generally associated with synthetic peptides hinders the practical use of such peptide-based injectable hydrogel. To overcome this drawback, here, we propose to use the peptides from hydrolyzed low-cost natural protein as an economical and convenient peptide source to prepare an injectable hydrogel. We demonstrate the effectiveness of this alternative strategy using hen egg white lysozyme (HEWL) as an example. We used the peptide fragments from hydrolyzed HEWL as the gelator, and the magnesium ion as the performance enhancer to prepare the injectable hydrogel. We showed that the hydrogel is an amyloid gel as it was formed by a dense network of amyloid fibrils. We also showed that the hydrogel possesses a thixotropic property and displays a low cytotoxicity. The hydrolysis extent of HEWL was found to be a critical factor that influences the performance of the hydrogel. A fluorescence assay based on 8-anilinonaphthalene-1-sulfonic acid was proposed as a mean to precisely and conveniently control the hydrolysis extent of HEWL to enable the best injectability performance. At last, using doxorubicin as a model compound, we explored the potential of this amyloid-based hydrogel as an injectable drug carrier.

Tissue Response and Biodistribution of Injectable Cellulose Nanocrystal Composite Hydrogels

Interest in cellulose nanocrystal (CNC)-based hydrogels for drug delivery, tissue engineering, and other biomedical applications has rapidly expanded despite the minimal in vivo research reported to date. Herein, we assess both in vitro protein adsorption and cell adhesion as well as in vivo subcutaneous tissue responses and CNC biodistribution of injectable CNC-poly(oligoethylene glycol methacrylate) (POEGMA) hydrogels. Hydrogels with different PEG side chain lengths, CNC loadings, and with or without in situ magnetic alignment of the CNCs are compared. CNC loading has a minimal impact on protein adsorption but significantly increases cell adhesion. In vivo, both CNC-only and CNC-POEGMA injections largely stay at their subcutaneous injection site over one month, with minimal bioaccumulation of CNCs in any typical clearance organ. CNC-POEGMA hydrogels exhibit mild acute and chronic inflammatory responses, although significant fibroblast penetration was observed with the magnetically aligned hydrogels. Collectively, these results suggest that CNC-POEGMA hydrogels offer promise in practical biomedical applications.

Targeting EZH2 for glioma therapy with a novel nanoparticle-siRNA complex

Background

For the past few years, gene-therapy has recently shown considerable clinical benefit in cancer therapy, and the applications of gene therapies in cancer treatments continue to increase perennially. EZH2, an ideal candidate for tumor gene therapy, plays an important role in the tumorigenesis.

Methods

In this study, we developed a novel gene delivery system with a self-assembly method by Methoxy polyethylene glycol-polycaprolactone (MPEG-PCL) and DOTAP(DMC). And EZH2si-DMC was used to research anti-glioma both in vitro and in vivo.

Results

DMC with zeta-potential value of 36.7 mV and size of 35.6 nm showed good performance in the delivery siRNA to glioma cell in vitro with high 98% transfection efficiency. EZH2si-DMC showed good anti-glioma effect in vitro through inducing cell apoptosis and inhibiting cell growth. What’s more, treatment of tumor-bearing mice with DMC-EZH2si complex had significantly inhibited tumor growth at the subcutaneous model in vivo by inhibiting EZH2 protein expression, promoting apoptosis and reducing proliferation.

Conclusion

The EZH2 siRNA and DMC complex may be used to treat the glioma in clinical as a new drug.

Functionalization of soft materials for cardiac repair and regeneration

Coronary artery disease is a leading cause of death in developed nations. As the disease progresses, myocardial infarction can occur leaving areas of dead tissue in the heart. To compensate, the body initiates its own repair/regenerative response in an attempt to restore function to the heart. These efforts serve as inspiration to researchers who attempt to capitalize on the natural regenerative processes to further augment repair. Thus far, researchers are exploiting these repair mechanisms in the functionalization of soft materials using a variety of growth factor-, ligand- and peptide-incorporating approaches. The goal of functionalizing soft materials is to best promote and direct the regenerative responses that are needed to restore the heart. This review summarizes the opportunities for the use of functionalized soft materials for cardiac repair and regeneration, and some of the different strategies being developed.

Graphene Nanomaterials-Based Radio-Frequency/Microwave Biosensors for Biomaterials Detection

In this paper, the advances in radio-frequency (RF)/microwave biosensors based on graphene nanomaterials including graphene, graphene oxide (GO), and reduced graphene oxide (rGO) are reviewed. From a few frontier studies, recently developed graphene nanomaterials-based RF/microwave biosensors are examined in-depth and discussed. Finally, the prospects and challenges of the next-generation RF/microwave biosensors for wireless biomedical applications are proposed.