Hematoma-like dynamic hydrogelation through natural glycopeptide molecular recognition for infected bone fracture repair

From hard tissues to beyond: Progress and challenges of strontium-containing biomaterials in regenerative medicine applications

Tissue engineering and regenerative medicine have emerged as crucial disciplines focused on the development of new tissues and organs to overcome the limitations of traditional treatments for tissue damage caused by accidents, diseases, or aging. Strontium ion (Sr2+) has garnered significant attention for its multifaceted role in promoting regeneration medicine and therapy, especially in bone tissue regeneration. Recently, numerous studies further confirm that Sr2+ also plays a critical in soft tissue regeneration. This review firstly summarizes the influence of Sr2+ on critical biological processes such as osteogenesis, angiogenesis, immune modulation, matrix synthesis, mineralization, and antioxidative defence mechanisms. Then details the classification, properties, advantages, and limitations of Sr-containing biomaterials (SrBMs). Additionally, this review extends to the current applications of SrBMs in regenerative medicine for diverse tissues, including bone, cartilage, skeletal muscle, dental pulp, cardiac tissue, skin, hair follicles, etc. Moreover, the review addresses the challenges associated with current SrBMs and provides insights for their future designing and applications in regenerative medicine.

Recent Advances in Peptide-Functionalized Hydrogels for Bone Tissue Engineering

Efficient therapeutic approaches for bone regeneration are urgently required to address the significant challenges associated with the repair of large-scale or long-segment bone defects. Peptide-functionalized hydrogels (PFHs) have emerged as important bioactive materials in bone tissue engineering because they produce biomimetic microenvironments enriched with multiple biochemical signals. This review summarizes the key fabrication techniques for PFHs and discusses their diverse applications in different fields. Furthermore, we systematically highlighted the biochemical functionalization of PFHs, which includes basic functions such as cell adhesion, cell recruitment, and osteoinduction; improved functions such as angiogenesis, biomineralization, immune regulation, and hormone regulation; and other functions, including antimicrobial and antitumor effects. Finally, critical biosafety considerations associated with PFHs and perspectives on developing intelligent PFHs are addressed. This review aims to inspire further research on PFHs and accelerate their applications in bone tissue engineering.

A review of self-healing hydrogels for bone repair and regeneration: Materials, mechanisms, and applications

Bone defects, which arise from various factors such as trauma, tumor resection, and infection, present a significant clinical challenge. There is an urgent need to develop new biomaterials capable of repairing a wide array of damage and defects in bone tissue. Self-healing hydrogels, a groundbreaking advancement in the field of biomaterials, displaying remarkable ability to regenerate damaged connections after partial severing, thus offering a promising solution for bone defect repair. This review first presents a comprehensive overview of the progress made in the design and preparation of these hydrogels, focusing on the self-healing mechanisms based on physical non-covalent interactions and dynamic chemical covalent bonds. Subsequently, the applications of self-healing hydrogels including natural polymers, synthetic polymers, and nano-hybrid materials, are discussed in detail, emphasizing their mechanisms in promoting bone tissue regeneration. Finally, the review addresses current challenges as well as future prospects for the use of hydrogels in bone repair and regeneration, identifying osteogenic properties, mechanical performance, and long-term biocompatibility as key areas for further improvement. In summary, this paper provides an in-depth analysis of recent advances in self-healing hydrogels for bone repair and regeneration, underscoring their immense potential for clinical application.

Dual peptide-coordinated dynamic hydrogel with antibacterial and proangiogenic activities for infected skin wounds

Infected skin wounds represent a class of significant clinical challenges due to their complexity and the risk of delayed healing. Developing an effective wound dressing capable of promoting tissue regeneration while addressing infections is crucial. In this study, we designed a dual peptide-coordinated dynamic hydrogel with both antibacterial and proangiogenic properties, specifically tailored for treating infected skin wounds. The dynamic hydrogel was constructed using gelatin, a natural biomacromolecule with high biocompatibility, as the base material. Two functional peptides, the antibacterial melittin and angiogenic peptide, were incorporated to enhance both infection control and tissue repair. Hydrogelation was achieved through coordination interactions between gold (Au) ions and sulfhydryl groups, endowing the hydrogel with dynamic properties. The excellent biocompatibility, antibacterial efficacy and angiogenic capability of hydrogel allow it to provide structural support for wound healing while promoting cell proliferation and migration. By eradicating bacteria and stimulating new blood vessel formation, it accelerates the healing of infected wounds. Additionally, its injectability and self-healing properties make it suitable for treating irregularly shaped and deep wounds. This dual-functional hydrogel may offer a promising and minimally invasive treatment option for infected skin wounds, combining high biological safety with simplified surgical procedures.

A multifunctional self-reinforced injectable hydrogel for enhancing repair of infected bone defects by simultaneously targeting macrophages, bacteria, and bone marrow stromal cells

Injectable hydrogels (IHs) have demonstrated huge potential in promoting repair of infected bone defects (IBDs), but how to endow them with desired anti-bacterial, immunoregulatory, and osteo-inductive properties as well as avoid mechanical failure during their manipulation are challenging. In this regard, we developed a multifunctional AOHA-RA/Lap nanocomposite IH for IBDs repair, which was constructed mainly through two kinds of reversible cross-links: (i) the laponite (Lap) crystals mediated electrostatic interactions; (ii) the phenylboronic acid easter bonds between the 4-aminobenzeneboronic acid grafted oxidized hyaluronic acid (AOHA) and rosmarinic acid (RA). Due to the specific structural composition, the AOHA-RA/Lap IH demonstrated superior injectability, self-recoverability, spatial adaptation, and self-reinforced mechanical properties after being injected to the bone defect site. In addition, the RA molecules could be locally released from the hydrogel following a Weibull model for over 10 days. Systematic in vitro/vivo assays proved the strong anti-bacterial activity of the hydrogel against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Moreover, its capability of inducing M2 polarization of macrophages (Mφ) and osteogenic differentiation of bone marrow stromal cells (BMSCs) was verified either, and the mechanism of the former was identified to be related to the JAK1-STAT1 and PI3K-AKT signaling pathways and that of the latter was identified to be related to the calcium signaling pathway, extracellular matrix (ECM) receptor interaction and TGF-β signaling pathway. After being implanted to a S. aureus infected rat skull defect model, the AOHA-RA/Lap IH significantly accelerated repair of IBDs without causing significant systemic toxicity. STATEMENT OF SIGNIFICANCE: Rosmarinic acid and laponite were utilized to develop an injectable hydrogel, promising for accelerating repair of infected bone defects in clinic. The gelation of the hydrogel was completely driven by two kinds of reversible cross-links, which endow the hydrogel superior spatial adaption, self-recoverability, and structural stability. The as-prepared hydrogel demonstrated superior anti-bacterial/anti-biofilm activity and could induce M2 polarization of macrophages and osteogenic differentiation of BMSCs. The mechanism behind macrophages polarization was identified to be related to the JAK1-STAT1 and PI3K-AKT signaling pathways. The mechanism behind osteogenic differentiation of BMSCs was identified to be related to the ECM receptor interaction and calcium signaling/TGF-β signaling pathways.

Multifunctional Glycopeptide-Based Hydrogel via Dual-Modulation for the Prevention and Repair of Radiation-Induced Skin Injury

The radiation-induced skin injury (RISI) remains a great challenge for clinical wound management and care after radiotherapy, as patients will suffer from the acute radiation injury and long-term chronic inflammatory damage during the treatment. The excessive ROS in the early acute stage and prolonged inflammatory response in the late healing process always hinder therapeutic efficiency. Herein, we developed an extracellular matrix (ECM)-mimetic multifunctional glycopeptide hydrogel (oCP@As) to promote and accelerate RISI repair via a dual-modulation strategy in different healing stages. The oCP@As hydrogel not only can form an ECM-like nanofiber structure through the Schiff base reaction but also exhibits ROS scavenging and DNA double-strand break repair abilities, which can effectively reduce the acute radiation damage. Meanwhile, the introduction of oxidized chondroitin sulfate, which is the ECM polysaccharide-like component, enables regulation of the inflammatory response by adsorption of inflammatory factors, accelerating the repair of chronic inflammatory injury. The animal experiments demonstrated that oCP@As can significantly weaken RISI symptoms, promote epidermal tissue regeneration and angiogenesis, and reduce pro-inflammatory cytokine expression. Therefore, this multifunctional glycopeptide hydrogel dressing can effectively attenuate RISI symptoms and promote RISI healing, showing great potential for clinical applications in radiotherapy protection and repair.

Macrophage membrane-reversibly camouflaged nanotherapeutics accelerate fracture healing by fostering MSCs recruitment and osteogenic differentiation

The fracture healing outcome is largely dependent on the quantities as well as osteogenic differentiation capacities of mesenchymal stem cells (MSCs) at the lesion site. Herein, macrophage membrane (MM)-reversibly cloaked nanocomplexes (NCs) are engineered for the lesion-targeted and hierarchical co-delivery of short stromal derived factor-1α peptide (sSDF-1α) and Ckip-1 small interfering RNA (Ckip-1 siRNA, siCkip-1) to promote bone repair by concurrently fostering recruitment and osteogenic differentiation of endogenous MSCs. To construct the NCs, a membrane-penetrating α-helical polypeptide first assembles with siCkip-1, and the cationic NCs are sequentially coated with catalase and an outer shell of sSDF-1α-anchored MM. Due to MM-assisted inflammation homing, intravenously injected NCs could efficiently accumulate at the fractured femur, where catalase decomposes the local hydrogen peroxide to generate oxygen bubbles that drives the shedding of sSDF-1α-anchored MM in the extracellular compartment. The exposed, cationic inner core thus enables robust trans-membrane delivery into MSCs to induce Ckip-1 silencing. Consequently, sSDF-1α-guided MSCs recruitment cooperates with siCkip-1-mediated osteogenic differentiation to facilitate bone formation and accelerate bone fracture healing. This study provides an enlightened strategy for the hierarchical co-delivery of macromolecular drugs into different cellular compartments, and it also renders a promising modality for the management of fracture healing.

Osteoking promotes bone formation and bone defect repair through ZBP1-STAT1-PKR-MLKL-mediated necroptosis

BACKGROUND

Osteoking has been used for fracture therapy with a satisfying clinical efficacy. However, its therapeutic properties and the underlying mechanisms remain elusive.

METHOD

A bone defect rat model was established to evaluate the pharmacological effects of Osteoking by the dynamic observation of X-ray, micro-CT and histopathologic examination. Transcriptome profiling was performed to identify bone defect-related genes and Osteoking effective targets. Then, a "disease-related gene-drug target" interaction network was constructed and a list of key network targets were screened, which were experimentally verified.

RESULTS

Osteoking effectively promoted bone defect repair in rats by accelerating the repair of cortical bone and the growth of trabeculae. Histopathologically, the bone defect rats displayed lower histopathologic scores in cortical bone, cancellous bone and bone connection than normal controls. In contrast, Osteoking exerted a favorable effect with a dose-dependent manner. The abnormal serum levels of bone turnover markers, bone growth factors and bone metabolism-related biochemical indexes in bone defect rats were also reversed by Osteoking treatment. Following the transcriptome-based network investigation, we hypothesized that osteoking might attenuate the levels of ZBP1-STAT1-PKR-MLKL-mediated necroptosis involved into bone defect. Experimentally, the expression levels of ZBP1, STAT1, PKR and the hallmark inflammatory cytokines for the end of necroptosis were distinctly elevated in bone defect rats, but were all effectively reversed by Osteoking treatment, which were also suppressed the activities of RIPK1, RIPK3 and MLKL in bone tissue supernatants.

CONCLUSIONS

Osteoking may promote bone formation and bone defect repair by regulating ZBP1-STAT1-PKR axis, leading to inhibit RIPK1/RIPK3/MLKL activation-mediated necroptosis.