Nanomaterials for the delivery of bioactive factors to enhance angiogenesis of dermal substitutes during wound healing

A bioactive hydrogel patch accelerates revascularization in ischemic lesions for tissue repair

Background

Magnesium ions play crucial roles in maintaining cellular functions. Research has shown that Mg2+ can promote angiogenesis, indicating its potential for treating cardiovascular ischemic diseases. However, conventional intravenous or oral administration of Mg2+ presents several challenges, including the risk of systemic side effects, diminished bioavailability, and a lack of targeted delivery mechanisms. In this study, we designed an Mg2+-releasing adhesive tissue patch (MgAP) that enables the dural release of Mg2+ ions.

Methods

A novel MgAP was developed on the basis of ionic crosslinking. Fourier transform infrared spectroscopy confirmed the chemical structure, whereas rheological analysis demonstrated stable mechanical properties and adaptability to dynamic loads. Sustained Mg2+ release was quantified over 7 days by inductively coupled plasma-mass spectrometry. In a rat acute myocardial infarction model, we performed echocardiography and strain analysis to assess cardiac function and histological staining to evaluate adverse remodeling. We also verified the proangiogenic effect through in vitro tube formation and in vivo immunofluorescence assays. Furthermore, transcriptomics and Western blotting were performed to explore the underlying mechanism. Additional assessments were also carried out in a rat model of lower limb ischemia.

Results

Compared with intravenous administration of magnesium chloride, MgAP application effectively improved cardiac function and reduced adverse remodeling in the myocardial infarction rat model. The left ventricular ejection fraction increased by 20.3 ± 6.6%, and the cardiac radial strain improved by 27.4 ± 4.1%. The cardiac fibrosis area and cell apoptosis rate decreased by 10.9 ± 1.2% and 32.1 ± 5.5%, respectively. RNA sequencing analysis also highlighted the upregulation of genes related to cardiac electrophysiological properties, structural and functional intercellular connections, and revascularization. The increased gap junction protein expression and restored local blood supply could contribute to the cardiac repair process posttreatment. The proangiogenic effect of MgAP was also observed in the rat limb ischemia model.

Conclusions

The above results revealed the convincing vascular regeneration effect of an ion therapy-based hydrogel, which enabled the local delivery of Mg2+ to the targeted ischemic tissue, aiding in cardiac and lower limb repair. This study presents a novel strategy and highlights its potential for use across various ischemic conditions.

Basic helix-loop-helix ARNT like 1 regulates the function of immune cells and participates in the development of immune-related diseases

The circadian clock is an internal timekeeper system that regulates biological processes through a central circadian clock and peripheral clocks controlling various genes. Basic helix-loop-helix ARNT-like 1 (BMAL1), also known as aryl hydrocarbon receptor nuclear translocator-like protein 1 (ARNTL1), is a key component of the circadian clock. The deletion of BMAL1 alone can abolish the circadian rhythms of the human body. BMAL1 plays a critical role in immune cell function. Dysregulation of BMAL1 is linked to immune-related diseases such as autoimmune diseases, infectious diseases, and cancer, and vice versa. This review highlights the significant role of BMAL1 in governing immune cells, including their development, differentiation, migration, homing, metabolism, and effector functions. This study also explores how dysregulation of BMAL1 can have far-reaching implications and potentially contribute to the onset of immune-related diseases such as autoimmune diseases, infectious diseases, cancer, sepsis, and trauma. Furthermore, this review discusses treatments for immune-related diseases that target BMAL1 disorders. Understanding the impact of BMAL1 on immune function can provide insights into the pathogenesis of immune-related diseases and help in the development of more effective treatment strategies. Targeting BMAL1 has been demonstrated to achieve good efficacy in immune-related diseases, indicating its promising potential as a targetable therapeutic target in these diseases.

Lymphangiogenesis: novel strategies to promote cutaneous wound healing

The cutaneous lymphatic system regulates tissue inflammation, fluid balance and immunological responses. Lymphangiogenesis or lymphatic dysfunction may lead to lymphedema, immune deficiency, chronic inflammation etc. Tissue regeneration and healing depend on angiogenesis and lymphangiogenesis during wound healing. Tissue oedema and chronic inflammation can slow wound healing due to impaired lymphangiogenesis or lymphatic dysfunction. For example, impaired lymphangiogenesis or lymphatic dysfunction has been detected in nonhealing wounds such as diabetic ulcers, venous ulcers and bedsores. This review summarizes the structure and function of the cutaneous lymphatic vessel system and lymphangiogenesis in wounds. Furthermore, we review wound lymphangiogenesis processes and remodelling, especially the influence of the inflammatory phase. Finally, we outline how to control lymphangiogenesis to promote wound healing, assess the possibility of targeting lymphangiogenesis as a novel treatment strategy for chronic wounds and provide an analysis of the possible problems that need to be addressed.

Integrating Bioactive Graded Hydrogel with Radially Aligned Nanofibers to Dynamically Manipulate Wound Healing Process

Skin wound healing is a complex process that requires appropriate treatment and management. Using a single scaffold to dynamically manipulate angiogenesis, cell migration and proliferation, and tissue reconstruction during skin wound healing is a great challenge. We developed a hybrid scaffold platform that integrates the spatiotemporal delivery of bioactive cues with topographical cues to dynamically manipulate the wound-healing process. The scaffold comprised gelatin methacryloyl hydrogels and electrospun poly(ε-caprolactone)/gelatin nanofibers. The hydrogels had graded cross-linking densities and were loaded with two different functional bioactive peptides. The nanofibers comprised a radially aligned nanofiber array layer and a layer of random fibers. During the early stages of wound healing, the KLTWQELYQLKYKGI peptide, which mimics vascular endothelial growth factor, was released from the inner layer of the hydrogel to accelerate angiogenesis. During the later stages of wound healing, the IKVAVS peptide, which promotes cell migration, synergized with the radially aligned nanofiber membrane to promote cell migration, while the nanofiber membrane also supported further cell proliferation. In an in vivo rat skin wound-healing model, the hybrid scaffold significantly accelerated wound healing and collagen deposition, and the ratio of type I to type III collagen at the wound site resembled that of normal skin. The prepared scaffold dynamically regulated the skin tissue regeneration process in stages to achieve rapid wound repair with clinical application potential, providing a strategy for skin wound repair.

[Preliminary application of antibiotic bone cement directly inducing skin regeneration technology in repairing of wound in lateral toe flap donor area]

Objective

To investigate the feasibility and effectiveness of antibiotic bone cement directly inducing skin regeneration technology in the repairing of wound in the lateral toe flap donor area.

Methods

Between June 2020 and February 2023, antibiotic bone cement directly inducing skin regeneration technology was used to repair lateral toe flap donor area in 10 patients with a total of 11 wounds, including 7 males and 3 females. The patients' age ranged from 21 to 63 years, with an average of 40.6 years. There were 3 cases of the distal segment of the thumb, 2 cases of the distal segment of the index finger, 1 case of the middle segment of the index and middle fingers, 1 case of the distal segment of the middle finger, and 3 cases of the distal segment of the ring finger. The size of the skin defect of the hand ranged from 2.4 cm×1.8 cm to 4.3 cm×3.4 cm. The disease duration ranged from 1 to 15 days, with an average of 6.9 days. The flap donor sites were located at fibular side of the great toe in 5 sites, tibial side of the second toe in 5 sites, and tibial side of the third toe in 1 site. The skin flap donor site wounds could not be directly sutured, with 2 cases having exposed tendons, all of which were covered with antibiotic bone cement.

Results

All patients were followed up 6 months to 2 years, with an average of 14.7 months. All the 11 flaps survived and had good appearance. The wound healing time was 40-72 days, with an average of 51.7 days. There was no hypertrophic scar in the donor site, which was similar to the color of the surrounding normal skin; the appearance of the foot was good, and wearing shoes and walking of the donor foot were not affected.

Conclusion

It is a feasible method to repair the wound in the lateral foot flap donor area with the antibiotic bone cement directly inducing skin regeneration technology. The wound heals spontaneously, the operation is simple, and there is no second donor site injury.

The Evolution of Current Concept of the Reconstructive Ladder in Plastic Surgery: The Emerging Role of Translational Medicine

Plastic surgeons have used the reconstructive ladder for many decades as a standard directory for complex trauma reconstruction with the goal of repairing body structures and restoring functionality. This consists of different surgical maneuvers, such as secondary intention and direct tissue closure, as well as more complex methods such as local tissue transfer and free flap. The reconstructive ladder represents widely known options achievable for tissue reconstruction and wound closure that puts at the bottom rung the simplest methods of reconstruction and strengthens the complexity by moving upward. Regenerative medicine and surgery constitute a quickly spreading area of translational research that can be employed by minimally invasive surgical strategies, with the aim of regenerating cells and tissues in vivo in order to reestablish normal function through the intrinsic potential of cells, in combination with biomaterials and appropriate biochemical stimuli. These translational procedures have the aim of creating an appropriate microenvironment capable of supporting the physiological cellular function to generate the desired cells or tissues and to generate parenchymal, stromal, and vascular components on demand, and above all to produce intelligent materials capable of determining the fate of cells. Smart technologies have been grown that give extra "rungs" on the classic reconstructive ladder to integrate a more holistic, patient-based approach with improved outcomes. This commentary presents the evolution of the traditional concept of the reconstructive ladder in the field of plastic surgery into a new course with the aim of achieving excellent results for soft tissue reconstruction by applying innovative technologies and biologically active molecules for a wide range of surgical diseases.

Accelerated Burn Healing in a Mouse Experimental Model Using α-Gal Nanoparticles

Macrophages play a pivotal role in the process of healing burns. One of the major risks in the course of burn healing, in the absence of regenerating epidermis, is infections, which greatly contribute to morbidity and mortality in such patients. Therefore, it is widely agreed that accelerating the recruitment of macrophages into burns may contribute to faster regeneration of the epidermis, thus decreasing the risk of infections. This review describes a unique method for the rapid recruitment of macrophages into burns and the activation of these macrophages to mediate accelerated regrowth of the epidermis and healing of burns. The method is based on the application of bio-degradable "α-gal" nanoparticles to burns. These nanoparticles present multiple α-gal epitopes (Galα1-3Galβ1-4GlcNAc-R), which bind the abundant natural anti-Gal antibody that constitutes ~1% of immunoglobulins in humans. Anti-Gal/α-gal nanoparticle interaction activates the complement system, resulting in localized production of the complement cleavage peptides C5a and C3a, which are highly effective chemotactic factors for monocyte-derived macrophages. The macrophages recruited into the α-gal nanoparticle-treated burns are activated following interaction between the Fc portion of anti-Gal coating the nanoparticles and the multiple Fc receptors on macrophage cell membranes. The activated macrophages secrete a variety of cytokines/growth factors that accelerate the regrowth of the epidermis and regeneration of the injured skin, thereby cutting the healing time by half. Studies on the healing of thermal injuries in the skin of anti-Gal-producing mice demonstrated a much faster recruitment of macrophages into burns treated with α-gal nanoparticles than in control burns treated with saline and healing of the burns within 6 days, whereas healing of control burns took ~12 days. α-Gal nanoparticles are non-toxic and do not cause chronic granulomas. These findings suggest that α-gal nanoparticles treatment may harness anti-Gal for inducing similar accelerated burn healing effects also in humans.