Injectable microsphere/hydrogel hybrid system containing heat shock protein as therapy in a murine myocardial infarction model

The microspheres/hydrogels scaffolds based on the proteins, nucleic acids, or polysaccharides composite as carriers for tissue repair: A review

There are many studies on specific macromolecules and their contributions to tissue repair. Macromolecules have supporting and protective effects in organisms and can help regrow, reshape, and promote self-repair and regeneration of damaged tissues. Macromolecules, such as proteins, nucleic acids, and polysaccharides, can be constructed into hydrogels for the preparation of slow-release drug agents, carriers for cell culture, and platforms for gene delivery. Hydrogels and microspheres are fabricated by chemical crosslinking or mixed co-deposition often used as scaffolds, drug carriers, or cell culture matrix, provide proper mechanical support and nutrient delivery, a well-conditioned environment that to promote the regeneration and repair of damaged tissues. This review provides a comprehensive overview of recent developments in the construction of macromolecules into hydrogels and microspheres based on the proteins, nucleic acids, polysaccharides and other polymer and their application in tissue repair. We then discuss the latest research trends regarding the advantages and disadvantages of these composites in repair tissue. Further, we examine the applications of microspheres/hydrogels in different tissue repairs, such as skin tissue, cartilage, tumor tissue, synovial, nerve tissue, and cardiac repair. The review closes by highlighting the challenges and prospects of microspheres/hydrogels composites.

A DUSP6 inhibitor suppresses inflammatory cardiac remodeling and improves heart function after myocardial infarction

Acute myocardial infarction (MI) results in loss of cardiomyocytes and abnormal cardiac remodeling with severe inflammation and fibrosis. However, how cardiac repair can be achieved by timely resolution of inflammation and cardiac fibrosis remains incompletely understood. Our previous findings have shown that dual-specificity phosphatase 6 (DUSP6) is a regeneration repressor from zebrafish to rats. In this study, we found that intravenous administration of the DUSP6 inhibitor (E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one (BCI) improved heart function and reduced cardiac fibrosis in MI rats. Mechanistic analysis revealed that BCI attenuated macrophage inflammation through NF-κB and p38 signaling, independent of DUSP6 inhibition, leading to the downregulation of various cytokines and chemokines. In addition, BCI suppressed differentiation-related signaling pathways and decreased bone-marrow cell differentiation into macrophages through inhibiting DUSP6. Furthermore, intramyocardial injection of poly (D, L-lactic-co-glycolic acid)-loaded BCI after MI had a notable effect on cardiac repair. In summary, BCI improves heart function and reduces abnormal cardiac remodeling by inhibiting macrophage formation and inflammation post-MI, thus providing a promising pro-drug candidate for the treatment of MI and related heart diseases. This article has an associated First Person interview with the first author of the paper.

Bio-Hybrid Hydrogels Incorporated into a System of Salicylic Acid-pH/Thermosensitive Nanocarriers Intended for Cutaneous Wound-Healing Processes

In this paper, the preparation method of bio-hybrid hydrogels incorporated into a system of salicylic acid-pH/thermosensitive nanocarriers to speed up the wound-healing process was developed. This combination creates a dual drug delivery system, which releases the model hydrophobic active substance-salicylic acid-in a gradual and controlled manner for an extended time. Our research team has determined the various properties of bio-hybrid hydrogels based on their physicochemical (swelling degree, and degradation), structural (FT-IR), morphological (SEM), and mechanical (elongation tests) traits. Moreover, empty pH/thermosensitive nanocarriers and their salicylic acid-containing systems were characterized using the following methods: DLS, TG/DTG, and DSC. Additionally, salicylic acid release profiles directly from thermosensitive nanocarriers were compared to the bio-hybrid matrix. These studies were conducted in PBS (pH = 7.4) for 7 days using the USP4 method. To evaluate the antibacterial properties of the obtained materials, the inhibition of growth of Staphylococcus aureus, Escherichia coli, Candida albicans, and Aspergillus niger-as the main microorganisms responsible for human infections-were tested. The obtained results indicated that the pH/thermosensitive nanocarrier-salicylic acid system and bio-hybrid hydrogels are characterized by antibacterial activity against both S. aureus and E. coli.

Advances in the stimuli-responsive injectable hydrogel for controlled release of drugs

The stimuli-responsiveness of injectable hydrogel has been drastically developed for the controlled release of drugs and achieved encouraging curative effects in a variety of diseases including wounds, cardiovascular diseases and tumors. The gelation, swelling and degradation of such hydrogels respond to endogenous biochemical factors (such as pH, reactive oxygen species, glutathione, enzymes, glucose) and/or to exogenous physical stimulations (like light, magnetism, electricity and ultrasound), thereby accurately releasing loaded drugs in response to specifically pathological status and as desired for treatment plan and thus improving therapeutic efficacy effectively. In this paper, we give a detailed introduction of recent progresses in responsive injectable hydrogels and focus on the design strategy of various stimuli-sensitivities and their resultant alteration of gel dissociation and drug liberation behaviour. Their application in disease treatment is also discussed. This article is protected by copyright. All rights reserved.

Engineering Hydrogels for the Development of Three-Dimensional In Vitro Models

The superiority of in vitro 3D cultures over conventional 2D cell cultures is well recognized by the scientific community for its relevance in mimicking the native tissue architecture and functionality. The recent paradigm shift in the field of tissue engineering toward the development of 3D in vitro models can be realized with its myriad of applications, including drug screening, developing alternative diagnostics, and regenerative medicine. Hydrogels are considered the most suitable biomaterial for developing an in vitro model owing to their similarity in features to the extracellular microenvironment of native tissue. In this review article, recent progress in the use of hydrogel-based biomaterial for the development of 3D in vitro biomimetic tissue models is highlighted. Discussions of hydrogel sources and the latest hybrid system with different combinations of biopolymers are also presented. The hydrogel crosslinking mechanism and design consideration are summarized, followed by different types of available hydrogel module systems along with recent microfabrication technologies. We also present the latest developments in engineering hydrogel-based 3D in vitro models targeting specific tissues. Finally, we discuss the challenges surrounding current in vitro platforms and 3D models in the light of future perspectives for an improved biomimetic in vitro organ system.

The inflammatory markers sST2, HSP27 and hsCRP as a prognostic biomarker panel in chronic heart failure patients

BACKGROUND

The inflammatory markers sST2, HSP27 and hsCRP have already been identified as prognostic markers in chronic heart failure (HF). Though individual biomarkers have proven their value in mortality risk prediction, the role of a multimarker strategy needs further evaluation.

MATERIALS AND METHODS

This is an exploratory reanalysis in chronic HF patients. Plasma HSP27, sST2 and hsCRP in outpatients with chronic HF were analysed. Patients were followed for a minimum of twelve months for the endpoint cardiovascular mortality and unplanned HF associated hospitalisation (=event). 15 year overall mortality was assessed retrospectively. The prognostic impact was assessed using a Cox proportional hazard model.

RESULTS

113 chronic HF patients were included. Median follow up time was 614 days and 37 patients (32.7%) experienced an event. A Kaplan-Meier analysis revealed that patients with increased sST2, HSP27 and hsCRP levels have significantly worse prognosis (p < 0.001). The use of a three-biomarker combination was superior in an independent risk prediction of an event (one high vs. two high: HR = 4.5, 95% CI: 1.3-15.5, p = 0.018; and one high vs. all high: HR = 9.8, 95% CI: 2.8-34.3, p < 0.001) as shown in a multivariable cox proportional hazard model. However, the biomarker panel did not predict 15 year overall mortality, in contrast to elevated HSP27 levels (p = 0.012).

CONCLUSIONS

The combination of all three markers is an independent predictor of cardiovascular death and unplanned HF associated hospitalisation but not overall mortality. Our findings suggest that adding those markers in combination to well established risk assessment parameters may improve risk stratification.

Targeted Delivery of Recombinant Heat Shock Protein 27 to Cardiomyocytes Promotes Recovery from Myocardial Infarction

Ischemic heart disease, especially myocardial infarction (MI), is the leading cause of death worldwide. Apoptotic mechanisms are thought to play a significant role in cardiomyocyte death after MI. Increased production of heat shock proteins (Hsps) in cardiomyocytes is a normal response to promote tolerance and to reduce cell damage. Hsp27 is considered to be a therapeutic option for the treatment of ischemic heart disease due to its protective effects on hypoxia-induced apoptosis. Despite its antiapoptotic effects, the lack of strategies to deliver Hsp27 to the heart tissue in vivo limits its clinical applicability. In this study, we utilized an antibody against the angiotensin II type 1 (AT1) receptor, which is expressed immediately after ischemia/reperfusion in the heart of MI rats. To achieve cardiomyocyte-targeted Hsp27 delivery after ischemia/reperfusion, we employed the immunoglobulin-binding dimer ZZ, a modified domain of protein A, in conjunction with the AT1 receptor antibody. Using the AT1 receptor antibody, we achieved systemic delivery of ZZ-TAT-GFP fusion protein into the heart of MI rats. This approach enabled selective delivery of Hsp27 to cardiomyocytes, rescued cells from apoptosis, reduced the area of fibrosis, and improved cardiac function in the rat MI model, thus suggesting its applicability as a cardiomyocyte-targeted protein delivery system to inhibit apoptosis induced by ischemic injury.

New Developments in Medical Applications of Hybrid Hydrogels Containing Natural Polymers

New trends in biomedical applications of the hybrid polymeric hydrogels, obtained by combining natural polymers with synthetic ones, have been reviewed. Homopolysaccharides, heteropolysaccharides, as well as polypeptides, proteins and nucleic acids, are presented from the point of view of their ability to form hydrogels with synthetic polymers, the preparation procedures for polymeric organic hybrid hydrogels, general physico-chemical properties and main biomedical applications (i.e., tissue engineering, wound dressing, drug delivery, etc.).

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.

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.