Self-reinforcement hydrogel with sustainable oxygen-supply for enhanced cell ingrowth and potential tissue regeneration

An injectable in situ-forming hydrogel with self-activating genipin-chitosan (GpCS) cross-linking and an O2/Ca2+ self-supplying capability for wound healing and rapid hemostasis

Severe traumatic bleeding and chronic diabetic wounds require rapid hemostasis and multifunctional dressings, which remain particularly challenging, especially for non-compressible trauma and irregular wounds with dysregulated microenvironments. Chitosan (CS) can be easily cross-linked with genipin to form GpCS hydrogels. However, developing injectable GpCS hydrogels for biomedical applications faces challenges, particularly in enhancing rapid gel formation and optimizing physical properties. In this study, we present an innovative approach to improve these aspects by designing a novel injectable GpCS hydrogel, strategically enhanced through a calcium peroxide (CaO2)-activated cross-linking reaction. CaO2 played a pivotal role in promoting in situ cross-linking of the GpCS hydrogel, leading to significant improvements in its injectable in situ gel-forming ability, mechanical strength, and self-healing and bioadhesive properties. CaO2 incorporated in the hydrogels rapidly converted to oxygen when combined with catalase (CAT), thereby establishing a self-sustaining oxygen/calcium release system. This system not only promoted hyperoxia and activated the coagulation cascade, facilitating rapid blood clotting, but also significantly accelerated wound healing through enhanced angiogenesis, collagen deposition, and M2 macrophage polarization. These attributes significantly enhanced the capacity of the hydrogel to facilitate wound closure and hemostasis, highlighting its therapeutic value in accelerating recovery and improving healing outcomes in clinical wound care.

Engineering next-generation oxygen-generating scaffolds to enhance bone regeneration

In bone, an adequate oxygen (O2) supply is crucial during development, homeostasis, and healing. Oxygen-generating scaffolds (OGS) have demonstrated significant potential to enhance bone regeneration. However, the complexity of O2 delivery and signaling in vivo makes it challenging to tailor the design of OGS to precisely meet this biological requirement. We review recent advances in OGS and analyze persisting engineering and translational hurdles. We also discuss the potential of computational and machine learning (ML) models to facilitate the integration of novel imaging data with biological readouts and advanced biomanufacturing technologies. By elucidating how to tackle current challenges using cutting-edge technologies, we provide insights for transitioning from traditional to next-generation OGS to improve bone regeneration in patients.

Advances in three-dimensional printing of hydrogel formulations for vascularized tissue and organ regeneration

Over the last decades, three-dimensional (3D) printing has emerged as one of the most promising alternative tissue and organ regeneration technologies. Recent advances in 3D printing technology, particularly in hydrogel-derived bioink formulations, offer promising solutions for fabricating intricate, biomimetic scaffolds that promote vascularization. In this review, we presented numerous studies that have been conducted to fabricate 3D-printed hydrogel vascularized constructs with significant advancements in printing integumentary systems, cardiovascular systems, vascularized bone tissues, skeletal muscles, livers, and kidneys. Furthermore, this work also discusses the engineering considerations, current challenges, proposed solutions, and future outlooks of 3D bioprinting.

Application of nanoparticles as surface modifiers of dental implants for revascularization/regeneration of bone

BACKGROUND

Osseointegrated dental implants are widely established as a first-choice treatment for the replacement of missing teeth. Clinical outcomes are however often compromised by short or longer-term biological complications and pathologies. Nanoparticle-coated materials represent a very active research area with the potential to enhance clinical outcomes and reduce complications of implant therapy. This scoping review aimed to summarize current research on various types of nanoparticles (NPs) used as surface modifiers of dental implants and their potential to promote biological and clinical outcomes.

METHODS

A systematic electronic search was conducted in SCOPUS, PubMed and Google Scholar aiming to identify in vivo, in situ, or in vitro studies published between 2014 and 2024. Inclusion and exclusion criteria were determined and were described in the methods section.

RESULTS

A total of 169 articles (44 original papers from Scopus and PubMed, and 125 articles from Google Scholar) were identified by the electronic search. Finally, 30 studies fit the inclusion criteria and were further used in this review. The findings from the selected papers suggest that nanoparticle-coated dental implants show promising results in enhancing bone regeneration and promoting angiogenesis around the implant site. These effects are due to the unique physicochemical properties of nanoparticle-coated implants and the controlled release of bioactive molecules from nanoparticle-modified surfaces.

CONCLUSION

Nanoscale modifications displayed unique properties which could significantly enhance the properties of dental implants and further accelerate revascularization, and osseointegration while facilitating early implant loading. Yet, since many of these findings were based on in-vitro/in-situ systems, further research is required before such technology reaches clinical application.

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.

Technology for the formation of engineered microvascular network models and their biomedical applications

Tissue engineering and regenerative medicine have made great progress in recent decades, as the fields of bioengineering, materials science, and stem cell biology have converged, allowing tissue engineers to replicate the structure and function of various levels of the vascular tree. Nonetheless, the lack of a fully functional vascular system to efficiently supply oxygen and nutrients has hindered the clinical application of bioengineered tissues for transplantation. To investigate vascular biology, drug transport, disease progression, and vascularization of engineered tissues for regenerative medicine, we have analyzed different approaches for designing microvascular networks to create models. This review discusses recent advances in the field of microvascular tissue engineering, explores potential future challenges, and offers methodological recommendations.

MnO2 Decorated Metal-Organic Framework-Based Hydrogel Relieving Tumor Hypoxia for Enhanced Photodynamic Therapy

Photodynamic therapy (PDT) has emerged as a promising cancer treatment modality; however, its therapeutic efficacy is greatly limited by tumor hypoxia. In this study, a metal-organic framework (MOF)-based hydrogel (MOF Gel) system that synergistically combines PDT with the supply of oxygen is designed. Porphyrin-based Zr-MOF nanoparticles are synthesized as the photosensitizer. MnO2 is decorated onto the surface of the MOF, which can effectively convert H₂O₂ into oxygen. Simultaneously, the incorporation of MnO2 -decorated MOF (MnP NPs) into a chitosan hydrogel (MnP Gel) serves to enhance its stability and retention at the tumor site. The results show that this integrated approach significantly improves tumor inhibition efficiency by relieving tumor hypoxia and enhancing PDT. Overall, the findings underscore the potential for employing nano-MOF-based hydrogel systems as promising agents for cancer therapy, thus advancing the application of multifunctional MOFs in cancer treatment.

Novel pH-Responsive CaO2@ZIF-67-HA-ADH Coating That Efficiently Enhances the Antimicrobial, Osteogenic, and Angiogenic Properties of Titanium Implants

Titanium-based implants often lead to premature implant failure due to the lack of antimicrobial, osteogenic, and angiogenic properties. To this end, a new strategy was developed to fabricate CaO2@ZIF-67-HA-ADH coating on titanium surfaces by combining calcium peroxide (CaO2) nanoparticles, zeolite imidazolate framework-67 (ZIF-67), and the chemical coupling hyaluronic acid-adipic acid dihydrazide (HA-ADH). We characterized CaO2@ZIF-67-HA-ADH with scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results demonstrated that CaO2@ZIF-67-HA-ADH was pH-sensitive and decomposed rapidly under acidic conditions, and it released inclusions slowly under neutral conditions. Antibacterial experiments showed that the CaO2@ZIF-67-HA-ADH coating had excellent antibacterial properties and effectively killed methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PAO-1). Cell experiments revealed that the CaO2@ZIF-67-HA-ADH coating promoted pro-osteoblast adhesion, proliferation, and differentiation and also promoted the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs), exhibiting excellent osteogenic and angiogenic properties. In in vivo animal implantation experiments, the CaO2@ZIF-67-HA-ADH coating exhibited strong antimicrobial activity early after implantation and excellent osseointegration later after implantation. In conclusion, the pH-responsive CaO2@ZIF-67-HA-ADH coating conferred excellent antibacterial, osteogenic, and angiogenic properties to titanium implants, which effectively enhanced osseointegration of the implants and prevented bacterial infection; the coating shows promise for use in the treatment of bone defects.