Photo-Crosslinked Polymeric Matrix with Antimicrobial Functions for Excisional Wound Healing in Mice

In situ light-activated materials for skin wound healing and repair: A narrative review

Dermal wounds are a major global health burden made worse by common comorbidities such as diabetes and infection. Appropriate wound closure relies on a highly coordinated series of cellular events, ultimately bridging tissue gaps and regenerating normal physiological structures. Wound dressings are an important component of wound care management, providing a barrier against external insults while preserving the active reparative processes underway within the wound bed. The development of wound dressings with biomaterial constituents has become an attractive design strategy due to the varied functions intrinsic in biological polymers, such as cell instructiveness, growth factor binding, antimicrobial properties, and tissue integration. Using photosensitive agents to generate crosslinked or photopolymerized dressings in situ provides an opportunity to develop dressings rapidly within the wound bed, facilitating robust adhesion to the wound bed for greater barrier protection and adaptation to irregular wound shapes. Despite the popularity of this fabrication approach, relatively few experimental wound dressings have undergone preclinical translation into animal models, limiting the overall integrity of assessing their potential as effective wound dressings. Here, we provide an up-to-date narrative review of reported photoinitiator- and wavelength-guided design strategies for in situ light activation of biomaterial dressings that have been evaluated in preclinical wound healing models.

Effectiveness of nursing intervention in the operating room to prevent pressure ulcer and wound infection in patients undergoing intertrochanteric fracture: A meta-analysis

In this study, a meta-analysis was conducted to comprehensively assess the effectiveness of nursing intervention in the operating room to prevent pressure ulcers and wound infections in patients with intertrochanteric fractures. A computerised search of PubMed, Cochrane Library, Embase, China National Knowledge Infrastructure (CNKI), VIP Database of Chinese Technical Periodicals, and Wanfang databases was performed to identify randomised controlled studies (RCTs) on the effectiveness of nursing intervention in the operating room for patients undergoing intertrochanteric fractures from the time of construction of the respective databases to June 2023. Two researchers independently searched and screened the literature, extracted information and performed quality assessments of the included literature. The meta-analysis was performed using RevMan 5.4 software. Eighteen studies were finally included, including 1517 patients, with 757 in the intervention group and 760 in the control group. The results showed that nursing intervention in the operating room significantly reduced the incidence of postoperative pressure ulcers in patients with intertrochanteric femoral fractures compared to the control group (1.69% vs. 6.01%, odds ratio [OR]: 0.32, 95% confidence interval [CI]: 0.18-0.57, p < 0.001) and reduced the incidence of surgical site wound infection (1.00% vs. 6.15%, OR: 0.23, 95% CI: 0.11-0.50, p < 0.001). Current evidence suggests that nursing intervention in the operating room is superior to routine care in reducing the incidence of pressure ulcers and wound infections in patients with intertrochanteric fractures and that such interventions should be promoted for clinical use.

Biomembrane-Based Nanostructure- and Microstructure-Loaded Hydrogels for Promoting Chronic Wound Healing

Wound healing is a complex and dynamic process, and metabolic disturbances in the microenvironment of chronic wounds and the severe symptoms they cause remain major challenges to be addressed. The inherent properties of hydrogels make them promising wound dressings. In addition, biomembrane-based nanostructures and microstructures (such as liposomes, exosomes, membrane-coated nanostructures, bacteria and algae) have significant advantages in the promotion of wound healing, including special biological activities, flexible drug loading and targeting. Therefore, biomembrane-based nanostructure- and microstructure-loaded hydrogels can compensate for their respective disadvantages and combine the advantages of both to significantly promote chronic wound healing. In this review, we outline the loading strategies, mechanisms of action and applications of different types of biomembrane-based nanostructure- and microstructure-loaded hydrogels in chronic wound healing.

Antibacterial smart hydrogels: New hope for infectious wound management

Millions of people die annually due to uncured wound infections. Healthcare systems incur high costs to treat wound infections. Tt is predicted to become more challenging due to the rise of multidrug-resistant conditions. During the last decades, smart antibacterial hydrogels could attract attention as a promising solution, especially for skin wound infections. These antibacterial hydrogels are termed 'smart' due to their response to specific physical and chemical environmental stimuli. To deliver different drugs to particular sites in a controlled manner, various types of crosslinking strategies are used in the manufacturing process. Smart hydrogels are designed to provide antimicrobial agents to the infected sites or are built from polymers with inherent disinfectant properties. This paper aims to critically review recent pre-clinical and clinical advances in using smart hydrogels against skin wound infections and propose the next best thing for future trends. For this purpose, an introduction to skin wound healing and disease is presented and intelligent hydrogels responding to different stimuli are introduced. Finally, the most promising investigations are discussed in their related sections. These studies can pave the way for producing new biomaterials with clinical applications.

Combination of an engineered Lactococcus lactis expressing CXCL12 with light-emitting diode yellow light as a treatment for scalded skin in mice

Impaired wound closure is an increasingly crucial clinical challenge. Recently, wound healing has shifted towards innovative treatments that exploit nanotechnology, biomaterials, biologics and phototherapy. Here, we constructed an engineered MG1363-pMG36e-mCXCL12 strain with pMG36e plasmid encoding stromal cell-derived factor 1α (named CXCL12) and evaluated the synergistic effects of light-emitting diode (LED) yellow light and MG1363-pMG36e-mCXCL12 on scald wounds in mice. The results indicated that the combined treatment with LED yellow light with mCXCL12 delivering strain accelerated wound closure, tissue remodelling, re-epithelialization and hair follicle regeneration and inhibited over-inflammation oppositely in the central and surrounding wounds by macroscopic, histopathologic and immunohistochemistry parameters. Furthermore, combination therapy increased the epidermal growth factor and Ki67-positive cells and upregulated beta-catenin (β-catenin), cellular-myelocytomatosis (c-Myc), wingless-type MMTV integration site family member 1 (Wnt1), Jagged 1, neurogenic locus notch homolog protein 1 (Notch 1) and hairy and enhancer of split 1 (Hes 1) protein levels of the Wnt and Notch signalling pathways. It also facilitated collagen fibrogenesis and deposition and improved the activities of hydroxyproline, superoxide dismutase and glutathione peroxidase in scalded granulation tissue, in addition to reducing the inflammatory factors interleukin 1 beta (IL-1β) and tumour necrosis factor alpha (TNF-α). The combined treatment effectively reduced skin pathogens Ralstonia and Acinetobacter to further reduce the risk of infection. Overall, combination of LED yellow light and MG1363-pMG36e-mCXCL12 represents a potential strategy for the treatment of cutaneous wounds.

(Photo-)crosslinkable gelatin derivatives for biofabrication applications

Over the recent decades gelatin has proven to be very suitable as an extracellular matrix mimic for biofabrication and tissue engineering applications. However, gelatin is prone to dissolution at typical cell culture conditions and is therefore often chemically modified to introduce (photo-)crosslinkable functionalities. These modifications allow to tune the material properties of gelatin, making it suitable for a wide range of biofabrication techniques both as a bioink and as a biomaterial ink (component). The present review provides a non-exhaustive overview of the different reported gelatin modification strategies to yield crosslinkable materials that can be used to form hydrogels suitable for biofabrication applications. The different crosslinking chemistries are discussed and classified according to their mechanism including chain-growth and step-growth polymerization. The step-growth polymerization mechanisms are further classified based on the specific chemistry including different (photo-)click chemistries and reversible systems. The benefits and drawbacks of each chemistry are also briefly discussed. Furthermore, focus is placed on different biofabrication strategies using either inkjet, deposition or light-based additive manufacturing techniques, and the applications of the obtained 3D constructs. STATEMENT OF SIGNIFICANCE: Gelatin and more specifically gelatin-methacryloyl has emerged to become one of the gold standard materials as an extracellular matrix mimic in the field of biofabrication. However, also other modification strategies have been elaborated to take advantage of a plethora of crosslinking chemistries. Therefore, a review paper focusing on the different modification strategies and processing of gelatin is presented. Particular attention is paid to the underlying chemistry along with the benefits and drawbacks of each type of crosslinking chemistry. The different strategies were classified based on their basic crosslinking mechanism including chain- or step-growth polymerization. Within the step-growth classification, a further distinction is made between click chemistries as well as other strategies. The influence of these modifications on the physical gelation and processing conditions including mechanical properties is presented. Additionally, substantial attention is put to the applied photoinitiators and the different biofabrication technologies including inkjet, deposition or light-based technologies.