Injectable Self-Oxygenating Cardio-Protective and Tissue Adhesive Silk-Based Hydrogel for Alleviating Ischemia After Mi Injury.

Myocardial infarction (MI) is a significant cardiovascular disease that restricts blood flow, resulting in massive cell death and leading to stiff and noncontractile fibrotic scar tissue formation. Recently, sustained oxygen release in the MI area has shown regeneration ability; however, improving its therapeutic efficiency for regenerative medicine remains challenging. Here, a combinatorial strategy for cardiac repair by developing cardioprotective and oxygenating hybrid hydrogels that locally sustain the release of stromal cell-derived factor-1 alpha (SDF) and oxygen for simultaneous activation of neovascularization at the infarct area is presented. A sustained release of oxygen and SDF from injectable, mechanically robust, and tissue-adhesive silk-based hybrid hydrogels is achieved. Enhanced endothelialization under normoxia and anoxia is observed. Furthermore, there is a marked improvement in vascularization that leads to an increment in cardiomyocyte survival by ≈30% and a reduction of the fibrotic scar formation in an MI animal rodent model. Improved left ventricular systolic and diastolic functions by ≈10% and 20%, respectively, with a ≈25% higher ejection fraction on day 7 are also observed. Therefore, local delivery of therapeutic oxygenating and cardioprotective hydrogels demonstrates beneficial effects on cardiac functional recovery for reparative therapy.

Noninvasive and Continuous Monitoring of On-Chip Stem Cell Osteogenesis Using a Reusable Electrochemical Immunobiosensor.

Noninvasive monitoring of biofabricated tissues during the biomanufacturing process is needed to obtain reproducible, healthy, and functional tissues. Measuring the levels of biomarkers secreted from tissues is a promising strategy to understand the status of tissues during biofabrication. Continuous and real-time information from cultivated tissues enables users to achieve scalable manufacturing. Label-free biosensors are promising candidates for detecting cell secretomes since they can be noninvasive and do not require labor-intensive processes such as cell lysing. Moreover, most conventional monitoring techniques are single-use, conducted at the end of the fabrication process, and, challengingly, are not permissive to in-line and continual detection. To address these challenges, we developed a noninvasive and continual monitoring platform to evaluate the status of cells during the biofabrication process, with a particular focus on monitoring the transient processes that stem cells go through during in vitro differentiation over extended periods. We designed and evaluated a reusable electrochemical immunosensor with the capacity for detecting trace amounts of secreted osteogenic markers, such as osteopontin (OPN). The sensor has a low limit of detection (LOD), high sensitivity, and outstanding selectivity in complex biological media. We used this OPN immunosensor to continuously monitor on-chip osteogenesis of human mesenchymal stem cells (hMSCs) cultured 2D and 3D hydrogel constructs inside a microfluidic bioreactor for more than a month and were able to observe changing levels of OPN secretion during culture. The proposed platform can potentially be adopted for monitoring a variety of biological applications and further developed into a fully automated system for applications in advanced cellular biomanufacturing.

Algae-Mediated Removal of Prevalent Genotoxic Antibiotics: Molecular Perspective on Algae-Bacteria Consortia and Bioreactor-Based Strategies.

Antibiotic pollution poses a potential risk of genotoxicity, as antibiotics released into the environment can induce DNA damage and mutagenesis in various organisms. This pollution, stemming from pharmaceutical manufacturing, agriculture, and improper disposal, can disrupt aquatic ecosystems and potentially impact human health through the consumption of contaminated water and food. The removal of genotoxic antibiotics using algae-mediated approaches has gained considerable attention due to its potential for mitigating the environmental and health risks associated with these compounds. The paper provides an in-depth examination of the molecular aspects concerning algae and bioreactor-driven methodologies utilized for the elimination of deleterious antibiotics. The molecular analysis encompasses diverse facets, encompassing the discernment and profiling of algae species proficient in antibiotic degradation, the explication of enzymatic degradation pathways, and the refinement of bioreactor configurations to augment removal efficacy. Emphasizing the significance of investigating algal approaches for mitigating antibiotic pollution, this paper underscores their potential as a sustainable solution, safeguarding both the environment and human health.

Multicomponent decellularized extracellular matrix of caprine small intestine submucosa based bioactive hydrogel promoting full-thickness burn wound healing in rabbits.

Effective treatment for full-thickness burn wounds has remained challenging for clinicians. Among various strategies, extracellular gel-based dressing materials have gained attention to promote effective and rapid wound healing. These gel-based materials are porous and have antioxidant, antibacterial, hydrophilic, biodegradation, and biocompatible properties and hence can be used to alleviate burn wound healing. In concurrence with these findings, the present study evaluates thermo-responsive and self-assembled decellularized extracellular matrix (ECM) of caprine small intestine submucosa (DG-SIS) gel-based dressing material for burn wound healing. To expedite healing and efficiently tackle excessive free radicals and bioburden at the burn wound site, DG-SIS gel is fortified with antibacterial components (zinc oxide nanoparticles; ZnO) and a potent antioxidant agent (Vitamin-C;Vt-C). ZnO- and Vt-C-enriched DG-SIS (DG-SIS/ZnO/Vt-C) gels significantly increased the antioxidant and antibacterial activity of the therapeutic hydrogel. Additionally, the fabricated DG-SIS/ZnO/Vt-C bioactive gel resulted in significant full-thickness burn wound contraction (97.75 % in 14 days), a lower inflammatory effect, and enhanced angiogenesis with the highest collagen synthesis (1.22 µg/mg in 14 days) at the wound site. The outcomes from this study demonstrate a synergistic effect of ZnO/Vt-C in the bioactive gel as an effective and inexpensive therapeutic approach for full-thickness burn wound treatment.

Smart Biomaterials in Biomedical Applications: Current Advances and Possible Future Directions.

Smart biomaterials with the capacity to alter their properties in response to an outside stimulus or from within the environment around them have picked up significant attention in the biomedical community. This is primarily due to the interest in their biomedical applications that may be anticipated from them in a considerable number of dynamic structures and devices. Shape-memory materials are some of these materials that have been exclusively used for these applications. They exhibit unique structural reconfiguration features they adapt as per the provided environmental conditions and can be designed for their enhanced biocompatibility. Numerous research initiatives have focused on these smart biocompatible materials over the last few decades to enhance their biomedical applications. Shape-memory materials play a significant role in this regard to meet new surgical and medical devices' requirements for special features and utility cases. Because of the favorable design variety, different biomedical shape-memory materials can be developed by modifying their chemical and physical behaviors to accommodate the desired requirements. In this review, recent advances and characteristics of smart biomaterials for biomedical applications are described. The authors also discuss about their clinical translations in tissue engineering, drug delivery, and medical devices.

Technological Interventions Enhancing Curcumin Bioavailability in Wound-Healing Therapeutics.

Wound healing has been a challenge in the medical field. Tremendous research has been carried out to expedite wound healing by fabricating various formulations, some of which are now commercially available. However, owing to their natural source, people have been attracted to advanced formulations with herbal components. Among various herbs, curcumin has been the center of attraction from ancient times for its healing properties due to its multiple therapeutic effects, including antioxidant, antimicrobial, anti-inflammatory, anticarcinogenic, neuroprotective, and radioprotective properties. However, curcumin has a low water solubility and rapidly degrades into inactive metabolites, which limits its therapeutic efficacy. Henceforth, a carrier system is needed to carry curcumin, guard it against degradation, and keep its bioavailability and effectiveness. Different formulations with curcumin have been synthesized, and exist in the form of various synthetic and natural materials, including nanoparticles, hydrogels, scaffolds, films, fibers, and nanoemulgels, improving its bioavailability dramatically. This review discusses the advances in different types of curcumin-based formulations used in wound healing in recent times, concentrating on its mechanisms of action and discussing the updates on its application at several stages of the wound healing process. Impact statement Curcumin is a herbal compound extracted from turmeric root and has been used since time immemorial for its health benefits including wound healing. In clinical formulations, curcumin shows low bioavailability, which mainly stems from the way it is delivered in the body. Henceforth, a carrier system is needed to carry curcumin, guard it against degradation, while maintaining its bioavailability and therapeutic efficacy. This review offers an overview of the advanced technological interventions through tissue engineering approaches to efficiently utilize curcumin in different types of wound healing applications.

Dual cross-linked gellan gum/gelatin-based multifunctional nanocomposite hydrogel scaffold for full-thickness wound healing.

Biological macromolecules are excellent materials for wound dressing owing to their similar structure to the extracellular matrix and adjustable physicochemical properties. This research focuses on fabricating biological macromolecule-based hydrogel with desirable antibacterial, antioxidant, controlled drug release, cytocompatibility, and wound healing properties. Herein, different concentrations of nanoceria (NC) and flurbiprofen (FLU) drug-loaded gellan gum/gelatin (GG/Ge) based dual crosslinked (Ionic and EDC/NHS coupling) hydrogels were engineered. All fabricated hydrogels were hydrophilic, biodegradable, good strength, porous, antioxidant, hemocompatible and cytocompatible. Among all, hydrogel loaded with 500 µg/ml NC (GG/Ge/NC@FLU) exhibited desirable antioxidant, antibacterial (killed Staphylococcus aureus and Escherichia coli within 12 h), hemocompatible, cytocompatible, supports oxidative-stressed L929 cell growth and acted as a controlled release matrix for FLU, following Fickian diffusion, Peppas Sahlin and Korsmeyer-Peppas drug release models. Furthermore, nanocomposite hydrogel (GG/Ge/NC@FLU)-treated wounds of rats on day 14 demonstrated significantly higher collagen synthesis, nearly 100 % wound contractions, and efficiently decreased the expression of TNF-α and IL-1 while increasing the production of IL-10 and TNF-ß3, indicating antiinflammatory activity, and effectively reduced the expression of VEGF gene indicating effective angiogenesis than all other controls. In conclusion, the fabricated multifunctional GG/Ge/NC@FLU nanocomposite hydrogel shows promising potential for effectively treating full-thickness wound healing in a rat model.

Self-oxygenation of engineered living tissues orchestrates osteogenic commitment of mesenchymal stem cells.

Oxygenating biomaterials can alleviate anoxic stress, stimulate vascularization, and improve engraftment of cellularized implants. However, the effects of oxygen-generating materials on tissue formation have remained largely unknown. Here, we investigate the impact of calcium peroxide (CPO)-based oxygen-generating microparticles (OMPs) on the osteogenic fate of human mesenchymal stem cells (hMSCs) under a severely oxygen deficient microenvironment. To this end, CPO is microencapsulated in polycaprolactone to generate OMPs with prolonged oxygen release. Gelatin methacryloyl (GelMA) hydrogels containing osteogenesis-inducing silicate nanoparticles (SNP hydrogels), OMPs (OMP hydrogels), or both SNP and OMP (SNP/OMP hydrogels) are engineered to comparatively study their effect on the osteogenic fate of hMSCs. OMP hydrogels associate with improved osteogenic differentiation under both normoxic and anoxic conditions. Bulk mRNAseq analyses suggest that OMP hydrogels under anoxia regulate osteogenic differentiation pathways more strongly than SNP/OMP or SNP hydrogels under either anoxia or normoxia. Subcutaneous implantations reveal a stronger host cell invasion in SNP hydrogels, resulting in increased vasculogenesis. Furthermore, time-dependent expression of different osteogenic factors reveals progressive differentiation of hMSCs in OMP, SNP, and SNP/OMP hydrogels. Our work demonstrates that endowing hydrogels with OMPs can induce, improve, and steer the formation of functional engineered living tissues, which holds potential for numerous biomedical applications, including tissue regeneration and organ replacement therapy.

Correction: Diniz et al. Silver Nanoparticles-Composing Alginate/Gelatine Hydrogel Improves Wound Healing In Vivo. Nanomaterials 2020, 10, 390.

In the original publication, there was a mistake in Figure 6 as published [...].

Tunable and Compartmentalized Multimaterial Bioprinting for Complex Living Tissue Constructs.

Recapitulating inherent heterogeneity and complex microarchitectures within confined print volumes for developing implantable constructs that could maintain their structure in vivo has remained challenging. Here, we present a combinational multimaterial and embedded bioprinting approach to fabricate complex tissue constructs that can be implanted postprinting and retain their three-dimensional (3D) shape in vivo. The microfluidics-based single nozzle printhead with computer-controlled pneumatic pressure valves enables laminar flow-based voxelation of up to seven individual bioinks with rapid switching between various bioinks that can solve alignment issues generated during switching multiple nozzles. To improve the spatial organization of various bioinks, printing fidelity with the z-direction, and printing speed, self-healing and biodegradable colloidal gels as support baths are introduced to build complex geometries. Furthermore, the colloidal gels provide suitable microenvironments like native extracellular matrices (ECMs) for achieving cell growths and fast host cell invasion via interconnected microporous networks in vitro and in vivo. Multicompartment microfibers (i.e., solid, core-shell, or donut shape), composed of two different bioink fractions with various lengths or their intravolume space filled by two, four, and six bioink fractions, are successfully printed in the ECM-like support bath. We also print various acellular complex geometries such as pyramids, spirals, and perfusable branched/linear vessels. Successful fabrication of vascularized liver and skeletal muscle tissue constructs show albumin secretion and bundled muscle mimic fibers, respectively. The interconnected microporous networks of colloidal gels result in maintaining printed complex geometries while enabling rapid cell infiltration, in vivo.

Immunomodulating Hydrogels as Stealth Platform for Drug Delivery Applications.

Non-targeted persistent immune activation or suppression by different drug delivery platforms can cause adverse and chronic physiological effects including cancer and arthritis. Therefore, non-toxic materials that do not trigger an immunogenic response during delivery are crucial for safe and effective in vivo treatment. Hydrogels are excellent candidates that can be engineered to control immune responses by modulating biomolecule release/adsorption, improving regeneration of lymphoid tissues, and enhancing function during antigen presentation. This review discusses the aspects of hydrogel-based systems used as drug delivery platforms for various diseases. A detailed investigation on different immunomodulation strategies for various delivery options and deliberate upon the outlook of such drug delivery platforms are conducted.

Hybrid extracellular vesicles-liposome incorporated advanced bioink to deliver microRNA.

In additive manufacturing, bioink formulations govern strategies to engineer 3D living tissues that mimic the complex architectures and functions of native tissues for successful tissue regeneration. Conventional 3D-printed tissues are limited in their ability to alter the fate of laden cells. Specifically, the efficient delivery of gene expression regulators (i.e. microRNAs (miRNAs)) to cells in bioprinted tissues has remained largely elusive. In this study, we explored the inclusion of extracellular vesicles (EVs), naturally occurring nanovesicles (NVs), into bioinks to resolve this challenge. EVs show excellent biocompatibility, rapid endocytosis, and low immunogenicity, which lead to the efficient delivery of miRNAs without measurable cytotoxicity. EVs were fused with liposomes to prolong and control their release by altering their physical interaction with the bioink. Hybrid EVs-liposome (hEL) NVs were embedded in gelatin-based hydrogels to create bioinks that could efficiently encapsulate and deliver miRNAs at the target site in a controlled and sustained manner. The regulation of cells' gene expression in a 3D bioprinted matrix was achieved using the hELs-laden bioink as a precursor for excellent shape fidelity and high cell viability constructs. Novel regulatory factors-loaded bioinks will expedite the translation of new bioprinting applications in the tissue engineering field.

Enzyme-Mediated Alleviation of Peroxide Toxicity in Self-Oxygenating Biomaterials.

Oxygen releasing biomaterials can facilitate the survival of living implants by creating environments with a viable oxygen level. Hydrophobic oxygen generating microparticles (HOGMPs) encapsulated calcium peroxide (CPO) have recently been used in tissue engineering to release physiologically relevant amounts of oxygen for several weeks. However, generating oxygen using CPO is mediated via the generation of toxic levels of hydrogen peroxide (H2 O2 ). The incorporation of antioxidants, such as catalases, can potentially reduce H2 O2 levels. However, the formulation in which catalases can most effectively scavenge H2 O2 within oxygen generating biomaterials has remained unexplored. In this study, three distinct catalase incorporation methods are compared based on their ability to decrease H2 O2 levels. Specifically, catalase is incorporated within HOGMPs, or absorbed onto HOGMPs, or freely laden into the hydrogel entrapping HOGMPs and compared with control without catalase. Supplementation of free catalase in an HOGMP-laden hydrogel significantly decreases H2 O2 levels reflecting a higher cellular viability and metabolic activity of all the groups. An HOGMP/catalase-laden hydrogel precursor solution containing cells is used as an oxygenating bioink allowing improved viability of printed constructs under severe hypoxic conditions. The combination of HOGMPs with a catalase-laden hydrogel has the potential to decrease peroxide toxicity of oxygen generating tissues.

Microfluidic fabrication of lipid nanoparticles for the delivery of nucleic acids.

Gene therapy has emerged as a potential platform for treating several dreaded and rare diseases that would not have been possible with traditional therapies. Viral vectors have been widely explored as a key platform for gene therapy due to their ability to efficiently transport nucleic acid-based therapeutics into the cells. However, the lack of precision in their delivery has led to several off-target toxicities. As such, various strategies in the form of non-viral gene delivery vehicles have been explored and are currenlty employed in several therapies including the SARS-CoV-2 vaccine. In this review, we discuss the opportunities lipid nanoparticles (LNPs) present for efficient gene delivery. We also discuss various synthesis strategies via microfluidics for high throughput fabrication of non-viral gene delivery vehicles. We conclude with the recent applications and clinical trials of these vehicles for the delivery of different genetic materials such as CRISPR editors and RNA for different medical conditions ranging from cancer to rare diseases.

Emerging Biopolymer-Based Bioadhesives.

Bioadhesives have been widely used in healthcare and biomedical applications due to their ease-of-operation for wound closure and repair compared to conventional suturing and stapling. However, several challenges remain for developing ideal bioadhesives, such as unsatisfied mechanical properties, non-tunable biodegradability, and limited biological functions. Considering these concerns, naturally derived biopolymers have been considered good candidates for making bioadhesives owing to their ready availability, facile modification, tunable mechanical properties, and desired biocompatibility and biodegradability. Over the past several years, remarkable progress has been made on biopolymer-based adhesives, covering topics from novel materials designs and advanced processing to clinical translation. The developed bioadhesives have been applied for diverse applications, including tissue adhesion, hemostasis, antimicrobial, wound repair/tissue regeneration, and skin-interfaced bioelectronics. Here in this comprehensive review, recent progress on biopolymer-based bioadhesives is summarized with focuses on clinical translations and multifunctional bioadhesives. Furthermore, challenges and opportunities such as weak adhesion strength at the hydrated state, mechanical mismatch with tissues, and unfavorable immune responses are discussed with an aim to facilitate the future development of high-performance biopolymer-based bioadhesives.

Self-Oxygenation of Tissues Orchestrates Full-Thickness Vascularization of Living Implants.

Bioengineering of tissues and organs has the potential to generate functional replacement organs. However, achieving the full-thickness vascularization that is required for long-term survival of living implants has remained a grand challenge, especially for clinically sized implants. During the pre-vascular phase, implanted engineered tissues are forced to metabolically rely on the diffusion of nutrients from adjacent host-tissue, which for larger living implants results in anoxia, cell death, and ultimately implant failure. Here it is reported that this challenge can be addressed by engineering self-oxygenating tissues, which is achieved via the incorporation of hydrophobic oxygen-generating micromaterials into engineered tissues. Self-oxygenation of tissues transforms anoxic stresses into hypoxic stimulation in a homogenous and tissue size-independent manner. The in situ elevation of oxygen tension enables the sustained production of high quantities of angiogenic factors by implanted cells, which are offered a metabolically protected pro-angiogenic microenvironment. Numerical simulations predict that self-oxygenation of living tissues will effectively orchestrate rapid full-thickness vascularization of implanted tissues, which is empirically confirmed via in vivo experimentation. Self-oxygenation of tissues thus represents a novel, effective, and widely applicable strategy to enable the vascularization living implants, which is expected to advance organ transplantation and regenerative medicine applications.

Programmable microbial ink for 3D printing of living materials produced from genetically engineered protein nanofibers.

Living cells have the capability to synthesize molecular components and precisely assemble them from the nanoscale to build macroscopic living functional architectures under ambient conditions. The emerging field of living materials has leveraged microbial engineering to produce materials for various applications but building 3D structures in arbitrary patterns and shapes has been a major challenge. Here we set out to develop a bioink, termed as "microbial ink" that is produced entirely from genetically engineered microbial cells, programmed to perform a bottom-up, hierarchical self-assembly of protein monomers into nanofibers, and further into nanofiber networks that comprise extrudable hydrogels. We further demonstrate the 3D printing of functional living materials by embedding programmed Escherichia coli (E. coli) cells and nanofibers into microbial ink, which can sequester toxic moieties, release biologics, and regulate its own cell growth through the chemical induction of rationally designed genetic circuits. In this work, we present the advanced capabilities of nanobiotechnology and living materials technology to 3D-print functional living architectures.

A Smartphone-Enabled Portable Digital Light Processing 3D Printer.

3D printing has emerged as an enabling approach in a variety of different fields. However, the bulk volume of printing systems limits the expansion of their applications. In this study, a portable 3D Digital Light Processing (DLP) printer is built based on a smartphone-powered projector and a custom-written smartphone-operated app. Constructs with detailed surface architectures, porous features, or hollow structures, as well as sophisticated tissue analogs, are successfully printed using this platform, by utilizing commercial resins as well as a range of hydrogel-based inks, including poly(ethylene glycol)-diacrylate, gelatin methacryloyl, or allylated gelatin. Moreover, due to the portability of the unique DLP printer, medical implants can be fabricated for point-of-care usage, and cell-laden tissues can be produced in situ, achieving a new milestone for mobile-health technologies. Additionally, the all-in-one printing system described herein enables the integration of the 3D scanning smartphone app to obtain object-derived 3D digital models for subsequent printing. Along with further developments, this portable, modular, and easy-to-use smartphone-enabled DLP printer is anticipated to secure exciting opportunities for applications in resource-limited and point-of-care settings not only in biomedicine but also for home and educational purposes.

Survival and Proliferation under Severely Hypoxic Microenvironments Using Cell-Laden Oxygenating Hydrogels.

Different strategies have been employed to provide adequate nutrients for engineered living tissues. These have mainly revolved around providing oxygen to alleviate the effects of chronic hypoxia or anoxia that result in necrosis or weak neovascularization, leading to failure of artificial tissue implants and hence poor clinical outcome. While different biomaterials have been used as oxygen generators for in vitro as well as in vivo applications, certain problems have hampered their wide application. Among these are the generation and the rate at which oxygen is produced together with the production of the reaction intermediates in the form of reactive oxygen species (ROS). Both these factors can be detrimental for cell survival and can severely affect the outcome of such studies. Here we present calcium peroxide (CPO) encapsulated in polycaprolactone as oxygen releasing microparticles (OMPs). While CPO releases oxygen upon hydrolysis, PCL encapsulation ensures that hydrolysis takes place slowly, thereby sustaining prolonged release of oxygen without the stress the bulk release can endow on the encapsulated cells. We used gelatin methacryloyl (GelMA) hydrogels containing these OMPs to stimulate survival and proliferation of encapsulated skeletal myoblasts and optimized the OMP concentration for sustained oxygen delivery over more than a week. The oxygen releasing and delivery platform described in this study opens up opportunities for cell-based therapeutic approaches to treat diseases resulting from ischemic conditions and enhance survival of implants under severe hypoxic conditions for successful clinical translation.