PEGylated liposomes encapsulating human hemoglobin enhance oxygen transfer and cell proliferation while decreasing cell hypoxia in fibrin

Fabricating oxygen self-supplying 3D printed bioactive hydrogel scaffold for augmented vascularized bone regeneration

Limited cells and factors, inadequate mechanical properties, and necrosis of defects center have hindered the wide clinical application of bone-tissue engineering scaffolds. Herein, we construct a self-oxygenated 3D printed bioactive hydrogel scaffold by integrating oxygen-generating nanoparticles and hybrid double network hydrogel structure. The hydrogel scaffold possesses the characteristics of extracellular matrix; Meanwhile, the fabricated hybrid double network structure by polyacrylamide and CaCl2-crosslinked sodium carboxymethylcellulose endows the hydrogel favorable compressive strength and 3D printability. Furthermore, the O2 generated by CaO2 nanoparticles encapsulated in ZIF-8 releases steadily and sustainably because of the well-developed microporous structure of ZIF-8, which can significantly promote cell viability and proliferation in vitro, as well as angiogenesis and osteogenic differentiation with the assistance of Zn2+. More significantly, the synergy of O2 and 3D printed pore structure can prevent necrosis of defects center and facilitate cell infiltration by providing cells the nutrients and space they need, which can further induce vascular network ingrowth and accelerate bone regeneration in all areas of the defect in vivo. Overall, this work provides a new avenue for preparing cell/factor-free bone-tissue engineered scaffolds that possess great potential for tissue regeneration and clinical alternative.

Oxygen-releasing biomaterials for chronic wounds breathing: From theoretical mechanism to application prospect

Chronic wounds have always been considered as "gordian knots" in medicine, in which hypoxia plays a key role in blocking healing. To address this challenge, although tissue reoxygenation therapy based on hyperbaric oxygen therapy (HBOT) has been performed clinically for several years, the bench to bedside still urges the evolution of oxygen-loading and -releasing strategies with explicit benefits and consistent outcome. The combination of various oxygen carriers with biomaterials has gained momentum as an emerging therapeutic strategy in this field, exhibiting considerable application potential. This review gives an overview of the essential relationship between hypoxia and delayed wound healing. Further, detailed characteristics, preparation methods and applications of various oxygen-releasing biomaterials (ORBMs) will be elaborated, including hemoglobin, perfluorocarbon, peroxide, and oxygen-generating microorganisms, those biomaterials are applied to load, release or generate a vast of oxygen to relieve the hypoxemia and bring the subsequent cascade effect. The pioneering papers regarding to the ORBMs practice are presented and trends toward hybrid and more precise manipulation are summarized.

Erythrocyte-Inspired Functional Materials for Biomedical Applications

Erythrocytes are the most abundant cells in the blood. As the results of long-term natural selection, their specific biconcave discoid morphology and cellular composition are responsible for gaining excellent biological performance. Inspired by the intrinsic features of erythrocytes, various artificial biomaterials emerge and find broad prospects in biomedical applications such as therapeutic delivery, bioimaging, and tissue engineering. Here, a comprehensive review from the fabrication to the applications of erythrocyte-inspired functional materials is given. After summarizing the biomaterials mimicking the biological functions of erythrocytes, the synthesis strategies of particles with erythrocyte-inspired morphologies are presented. The emphasis is on practical biomedical applications of these bioinspired functional materials. The perspectives for the future possibilities of the advanced erythrocyte-inspired biomaterials are also discussed. It is hoped that the summary of existing studies can inspire researchers to develop novel biomaterials; thus, accelerating the progress of these biomaterials toward clinical biomedical applications.

Photosynthetic microorganisms for the oxygenation of advanced 3D bioprinted tissues

3D bioprinting technology has emerged as a tool that promises to revolutionize the biomedical field, including tissue engineering and regeneration. Despite major technological advancements, several challenges remain to be solved before 3D bioprinted tissues could be fully translated from the bench to the bedside. As oxygen plays a key role in aerobic metabolism, which allows energy production in the mitochondria; as a consequence, the lack of tissue oxygenation is one of the main limitations of current bioprinted tissues and organs. In order to improve tissue oxygenation, recent approaches have been established for a broad range of clinical applications, with some already applied using 3D bioprinting technologies. Among them, the incorporation of photosynthetic microorganisms, such as microalgae and cyanobacteria, is a promising approach that has been recently explored to generate chimerical plant-animal tissues where, upon light exposure, oxygen can be produced and released in a localized and controlled manner. This review will briefly summarize the state-of-the-art approaches to improve tissue oxygenation, as well as studies describing the use of photosynthetic microorganisms in 3D bioprinting technologies. STATEMENT OF SIGNIFICANCE: 3D bioprinting technology has emerged as a tool for the generation of viable and functional tissues for direct in vitro and in vivo applications, including disease modeling, drug discovery and regenerative medicine. Despite the latest advancements in this field, suboptimal oxygen delivery to cells before, during and after the bioprinting process limits their viability within 3D bioprinted tissues. This review article first highlights state-of-the-art approaches used to improve oxygen delivery in bioengineered tissues to overcome this challenge. Then, it focuses on the emerging roles played by photosynthetic organisms as novel biomaterials for bioink generation. Finally, it provides considerations around current challenges and novel potential opportunities for their use in bioinks, by comparing latest published studies using algae for 3D bioprinting.

3D-printed oxygen-releasing scaffolds improve bone regeneration in mice

Low oxygen (O₂) diffusion into large tissue engineered scaffolds hinders the therapeutic efficacy of transplanted cells. To overcome this, we previously studied hollow, hyperbarically-loaded microtanks (μtanks) to serve as O₂ reservoirs. To adapt these for bone regeneration, we fabricated biodegradable μtanks from polyvinyl alcohol and poly (lactic-co-glycolic acid) and embedded them to form 3D-printed, porous poly-ε-caprolactone (PCL)-μtank scaffolds. PCL-μtank scaffolds were loaded with pure O₂ at 300-500 psi. When placed at atmospheric pressures, the scaffolds released O₂ over a period of up to 8 h. We confirmed the inhibitory effects of hypoxia on the osteogenic differentiation of human adipose-derived stem cells (hASCs and we validated that μtank-mediated transient hyperoxia had no toxic impacts on hASCs, possibly due to upregulation of endogenous antioxidant regulator genes. We assessed bone regeneration in vivo by implanting O₂-loaded, hASC-seeded, PCL-μtank scaffolds into murine calvarial defects (4 mm diameters × 0.6 mm height) and subcutaneously (4 mm diameter × 8 mm height). In both cases we observed increased deposition of extracellular matrix in the O₂ delivery group along with greater osteopontin coverages and higher mineral deposition. This study provides evidence that even short-term O₂ delivery from PCL-μtank scaffolds may enhance hASC-mediated bone tissue regeneration.

Oxygen-Releasing Biomaterials: Current Challenges and Future Applications

Oxygen is essential for the survival, function, and fate of mammalian cells. Oxygen tension controls cellular behaviour via metabolic programming, which in turn controls tissue regeneration, stem cell differentiation, drug metabolism, and numerous pathologies. Thus, oxygen-releasing biomaterials represent a novel and unique strategy to gain control over a variety of in vivo processes. Consequently, numerous oxygen-generating or carrying materials have been developed in recent years, which offer innovative solutions in the field of drug efficiency, regenerative medicine, and engineered living systems. In this review, we discuss the latest trends, highlight current challenges and solutions, and provide a future perspective on the field of oxygen-releasing materials.

Crosslinked Hyaluronic Acid Gels with Blood-Derived Protein Components for Soft Tissue Regeneration

Hyaluronic acid (HA) is an ideal initial material for preparing hydrogels, which may be used as scaffolds in soft tissue engineering based on their advantageous physical and biological properties. In this study, two crosslinking agents, divinyl sulfone (DVS) and butanediol diglycidyl ether, were used to investigate their effect on the properties of HA hydrogels. As HA hydrogels alone do not promote cell adhesion on the scaffold, fibrin and serum from platelet-rich fibrin (SPRF) were combined with the scaffold; the aim was to create a material intended to be used as soft tissue implant that facilitates new tissue formation, and degrades over time. The chemical changes were characterized and cell attachment capacity of the protein-containing gels was examined using human mesenchymal stem cells, and viability was assessed using live-dead staining. Fourier-transform infrared measurements revealed that linking fibrin into the gel was more effective than linking SPRF. The scaffolds were found to be able to support cell adherence onto the hydrogels, and the best result was achieved when HA was crosslinked with DVS and contained fibrin. The most promising derivative, 5% DVS-crosslinked fibrin-containing hydrogel, was injected subcutaneously into C57BL/6 mice for 12 weeks. The scaffold was proven to be biocompatible, remodeling, and vascularization occurred, while shape and integrity were maintained. Impact statement Fibrin was combined with crosslinked hyaluronic acid (HA) for regenerative application, the structure of the combination of crosslinked HA with blood-derived protein was analyzed and effective coating was proven. It was observed that the fibrin content led to better mesenchymal stem cell attachment in vitro. The compositions showed biocompatibility, connective tissue and vascularization took place when implanted in vivo. Thus, a biocompatible, injectable gel was produced, which is a potential candidate for soft tissue implantation.

Oxygen Delivering Biomaterials for Tissue Engineering

Tissue engineering (TE) has provided promising strategies for regenerating tissue defects, but few TE approaches have been translated for clinical applications. One major barrier in TE is providing adequate oxygen supply to implanted tissue scaffolds, since oxygen diffusion from surrounding vasculature in vivo is limited to the periphery of the scaffolds. Moreover, oxygen is also an important signaling molecule for controlling stem cell differentiation within TE scaffolds. Various technologies have been developed to increase oxygen delivery in vivo and enhance the effectiveness of TE strategies. Such technologies include hyperbaric oxygen therapy, perfluorocarbon- and hemoglobin-based oxygen carriers, and oxygen-generating, peroxide-based materials. Here, we provide an overview of the underlying mechanisms and how these technologies have been utilized for in vivo TE applications. Emerging technologies and future prospects for oxygen delivery in TE are also discussed to evaluate the progress of this field towards clinical translation.

Star-shaped polymer consisting of a porphyrin core and poly(L-lysine) dendron arms: synthesis, drug delivery, and in vitro chemo/photodynamic therapy

A novel star-shaped polymer, porphyrin-poly(L-lysine) dendrons (PP-PLLD), is synthesized by the click reaction between azido-modified porphyrin and propargyl focal point poly(L-lysine) dendrons. Its chemical structure is characterized by (1) H nuclear magnetic resonance, Fourier transform infrared spectroscopy, and gel permeation chromatography (GPC) is analyses etc. Due to its amphiphilic property, the obtained PP-PLLD has a low critical micelle concentration in an aqueous solution, and can load doxorubicin (DOX) with a loading amount of 64 μg mg(-1) . By in vitro toxicity assay, PP-PLLD has no dark cytotoxicity but has significant phototoxicity. Moreover, DOX-loaded PP-PLLD shows a higher cytotoxicity under the light condition than PP-PLLD or DOX alone, suggesting PP-PLLD has a potential application in combined photodynamic therapy and chemotherapy.

Polymer nanoreactors with dual functionality: simultaneous detoxification of peroxynitrite and oxygen transport

The design of multifunctional systems is in focus today as a key strategy for coping with complex challenges in various domains that include chemistry, medicine, environmental sciences, and technology. Herein, we introduce protein-containing polymer nanoreactors with dual functionality: peroxynitrite degradation and oxygen transport. Vesicles made of poly-(2-methyloxazoline)-poly(dimethylsiloxane)-poly(2-methyloxazoline) successfully encapsulated hemoglobin (Hb), which serves as a model protein because of its dual function in oxygen transport and peroxynitrite degradation. By inserting channel proteins, the polymer membranes of vesicles permitted passage of various compounds that served for the assessment of in situ Hb activity. The requisite conformational changes in the protein structure and the change in oxidation states that took place within the confined space of the vesicle cavity demonstrated that Hb preserved its dual functionality: peroxynitrite degradation and oxygen transport. The functionality of our nanoreactor, combined with its simple procedure of production and extensive stability over several months, supports it as a promising system for further medical applications.

Liposome technology for cardiovascular disease treatment and diagnosis

INTRODUCTION

Over the past several decades, liposomes have been used in a variety of applications, from delivery vehicles to cell membrane models. In terms of pharmaceutical use, they can offer control over the release of active agents encapsulated into their lipid bilayer or aqueous core, while providing protection from degradation in the body. In addition, liposomes are versatile carriers, because targeting moieties can be conjugated on the surface to enhance delivery efficiency. It is for these reasons that liposomes have been applied as carriers for a multitude of drugs and genetic material, and as contrast agents, aimed to treat and diagnose cardiovascular diseases.

AREAS COVERED

This review details advancements in liposome technology used in the field of cardiovascular medicine. In particular, the application of liposomes to cardiovascular disease treatment and diagnosis, with a focus on delivering drugs, genetic material and improving cardiovascular imaging, will be explored. Advances in targeting liposomes to the vasculature will also be detailed.

EXPERT OPINION

Liposomes may provide the means to deliver drugs and other pharmaceutical agents for cardiovascular applications; however, there is still a vast amount of research and clinical trials that must be performed before a formulation is brought to market. Advancements in targeting abilities within the body, as well as the introduction of theranostic liposomes, capable of both delivering treating and imaging cardiac diseases, may be expected in the future of this burgeoning field.

Nanocarrier possibilities for functional targeting of bioactive peptides and proteins: state-of-the-art

This review attempts to provide an updated compilation of studies reported in the literature pertaining to production of nanocarriers encasing peptides and/or proteins, in a way that helps the reader direct a bibliographic search and develop an integrated perspective of the subject. Highlights are given to bioactive proteins and peptides, with a special focus on those from dairy sources (including physicochemical characteristics and properties, and biopharmaceutical application possibilities of e.g. lactoferrin and glycomacropeptide), as well as to nanocarrier functional targeting. Features associated with micro- and (multiple) nanoemulsions, micellar systems, liposomes and solid lipid nanoparticles, together with biopharmaceutical considerations, are presented in the text in a systematic fashion.