GOx/Hb Cascade Oxidized Crosslinking of Silk Fibroin for Tissue-Responsive Wound Repair

Promising wound dressings can achieve rapid soft-tissue filling while refactoring the biochemical and biophysical microenvironment to recruit endogenous cells, facilitating tissue healing, integration, and regeneration. In this study, a tissue biomolecule-responsive hydrogel matrix, employing natural silk fibroin (SF) as a functional biopolymer and haemoglobin (Hb) as a peroxidase-like biocatalyst, was fabricated through cascade enzymatic crosslinking. The hydrogels possessed mechanical tunability and displayed adjustable gelation times. A tyrosine unit on SF stabilised the structure of Hb during the cascade oxidation process; thus, the immobilized Hb in SF hydrogels exhibited higher biocatalytic efficiency than the free enzyme system, which provided a continuously antioxidative system. The regulation of the dual enzyme ratio endowed the hydrogels with favourable biocompatibility, biodegradability, and adhesion strength. These multifunctional hydrogels provided a three-dimensional porous extracellular matrix-like microenvironment for promoting cell adhesion and proliferation. A rat model with a full-thickness skin defect revealed accelerated wound regeneration via collagen deposition, re-epithelialisation and revascularisation. Enzyme-loaded hydrogels are an attractive and high-safety biofilling material with the potential for wound healing, tissue regeneration, and haemostasis.

Penetrating Brain Trauma due to Air Gun Shot – a Case Report

Cases of severe injuries caused by air guns are really uncommon, but they can lead to a fatal outcome. Usually, these injuries occur in children due to their not fully developed skull bones or in adults through less resistant and thin regions of the cranium. Most of them are accidental events, followed by low percentage of suicidal attempts. In this paper, we present the case of a 68-year-old man suffering from severe depression, with self-inflicted air gun injury to the head. The patient was admitted to the hospital in a coma with a Glasgow Coma Scale (GCS) score of 8, with severe penetrating head injury manifested with brain contusion and intraventricular bleeding seen at the CT examination. Metal particles from the projectile were seen inside the brain. The entry wound had inverted margins, abraded collar and skin defect. The additional neurological examination of the patient showed symptoms of increased intracranial pressure. The treatment started with the air gun wound care. Craniotomy surgery was also done and bone fragments around the entry wound were successfully extracted with subsequent debridement and duraplasty. The patient was treated with new-generation combined antibiotics for preventing inflammatory complications. On the nineteenth day, the patient was discharged with mild hemiparesis on the left side and with GCS score of 15. Air-gun traumatic cases with head injury or with injury to other parts of the body are often mistaken for firearm accidents, because air guns are seriously underestimated devices. Nevertheless, they could lead to severe health consequences and severe disability. This case highlights the necessity of strict monitoring of air guns by the responsible government institutions which should apply the same regulations in controlling these weapons as they implement in controlling the firearm guns. Presence of severe depression, mental illnesses, and neoplasms are risk factors for committing suicide with this type of weapons and the control over the air weapons in this group of people should be stricter.

Highly Adhesive Antibacterial Bioactive Composite Hydrogels With Controllable Flexibility and Swelling as Wound Dressing for Full-Thickness Skin Healing

Polyzwitterionic hydrogels as skin wound dressings have been extensively studied owing to their superior antibacterial properties and skin adhesiveness, but their practical applications still suffer from a low adhesion strength and a high swelling ratio, which hinder the application of hydrogel for cutaneous healing. Here, we developed a novel biocompatible poly[2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (PolySBMA) composite hydrogel with high stretchability, low swelling, strong skin adhesiveness, and antibacterial effect for enhancing wound healing. Naturally rigid polymers including quaternized chitosan methacrylate (QCSMA) and gelatin methacrylate (GelMA) are used as bioactive cross-linkers to endow PolySBMA/QCSMA/GelMA (SQG) hydrogel with a low swelling ratio and high bioactivity. The optimized hydrogel has excellent mechanical flexibility, with the ultimate tensile strength, tensile strain, modulus, and toughness of up to 344.5 kPa, 364%, 14.7 kPa, and 33.4 kJ m−3, respectively. The adhesiveness of the hydrogel to the skin tissue is as high as 38.2 kPa, which is critical for stopping the bleeding from the wound. The synergistic contributions from the PolySBMA and QCSMA endow hydrogel with good antibacterial properties against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Moreover, the natural polymer cross-linked polyzwitterionic hydrogel shows good cell activity, hemocompatibility, and histocompatibility. The in vivo full-thickness skin defect model demonstrates that the SQG hydrogel efficiently improves the granulation tissue formation and collagen deposition. In summary, such superiorly skin-adhesive antibacterial biocompatible hydrogel with controllable flexibility and swelling holds great promise as wound dressings for acute wounds.

Single, large, meshed full-thickness free skin graft for reconstruction of a dorsal lumbosacral wound defect in a dog

CASE DESCRIPTION A 12-year-old 32-kg neutered female crossbreed dog was treated for a large lumbosacral skin defect. CLINICAL FINDINGS The dog had sustained multiple, penetrating dog bite wounds to the lumbosacral and gluteal regions 5 days earlier. The referring veterinarian had initiated treatment with amoxicillin–clavulanic acid, which was continued at a dosage of 8.75 mg/kg, SC, every 24 hours at the referral hospital. Examination of the skin defect revealed a large subcutaneous abscess in the dorsal lumbosacral region with draining perimeter tracts at the wound margin. The partial-thickness wound measured 24 × 35 cm and had multifocal regions of necrosis extending caudally from the dorsal aspect of the T11 vertebra to the tail base. The skin defect was bounded by discolored and necrotic skin edges. TREATMENT AND OUTCOME The dog underwent extensive soft tissue wound reconstruction. A single, large, meshed full-thickness free skin graft was harvested from the left dorsolateral aspect of the thorax and grafted to the dorsal lumbosacral region, thereby enabling successful closure of the wound defect. Primary healing of the wound eventually occurred, without postoperative complications. CLINICAL RELEVANCE Use of a large, meshed full-thickness free skin graft led to a satisfactory outcome for this dog but required challenging postoperative management. Application of single, large, meshed full-thickness free skin grafts may be an option to manage large skin deficits in the lumbosacral area in dogs.

Clinical application of both amniotic membranes and adipose derived mesenchymal stem cells in a cat with a large skin defect

Surgical procedures on large skin defects can be challenging in the short term due to the size of the lesion, infection, and tissue defect. A regenerative therapy for skin wounds has been applied to promote the healing process. An 8-month-old, Korean domestic short-haired female cat, weighing 3 kg, was rescued with extensive defects on the right flank to right inguinal region caused by bite wounds. In this case, amniotic membranes and adipose-derived mesenchymal stem cells were used as the regenerative therapy to treat the large skin defect rather than a surgical intervention alone. To the best of our knowledge, this is the first report of a case with of a large skin defect treated by applying allogeneic amniotic membranes and allogeneic mesenchymal stem cells to a cat.

Triggering Drug Release and Thermal-Disrupting Interface Induced Mitigation of Composite Photothermal Hydrogel Treating Infectious Wounds

Introduction: With the development of photothermal technology, the appearance of composite photothermal hydrogels has increased the selectivity of treating infectious skin defects. However, how to design composite photothermal hydrogel with better antibacterial performance, reduce the resistance rate of bacteria, and the damage rate of normal tissue still needs further study.Methods: The Prussian blue and tannic acid were loaded on polyacrylamide hydrogels. Characterization of DLS, Zeta potential, UV absorption spectrum, hydrogel swelling rate, scanning electronic microscopic, drug release profile, photothermal properties, in vitro cytocompatibility, and antibacterial properties. Experiments were measured by skin defect repair, antibacterial detection, and histological staining experiments.Results: The polyacrylamide hydrogel with photothermal effect and controllable release of tannic acid was successfully prepared. The hydrogel has strong light transmittance and adhesion, and the swelling rate can reach 600%, which improves the self-cleaning ability. SEM results showed the porous structure of hydrogels, promoting cell growth. Through photothermal switches, the composite hydrogel represented adjustable and controllable drug release ability. Combined with the synergistic antibacterial effect of tannic acid, this further enhanced the antibacterial ability and reduced the probability of antibiotic resistance. The in vitro and in vivo experiments showed the hydrogel had good biocompatibility and excellent antibacterial properties, which could promote the repair of infectious skin defects in SD rats.Conclusion: We fabricated a hydrogel with a triggering drug release rate, alleviating heat damage, transparent morphology, mechanical stability, strong adhesion, good biocompatibility, and synergistic antibacterial ability, which presents new treatment options for infectious skin defect repair.

Features of engraftment and rejection of ear alatransplants in laboratory rats

A method for revealing genetic affinity between laboratory rats has been developed, which is based on the transplantation of ear skin-chondrocyte allografts onto the surface of a full-thickness skin defect. On the example of Wistar rats (laboratory rats were taken from three research institutes), it was shown that the rejection of allografts occurs in the interval between 8 and 21 days with the same genetic differences that existed between the animals. However, at the same time, only those structures of ear allografts such as the dermis, epidermis and its derivatives die and are rejected, but the layers of chondrocytes are submerged under the granulation tissue and remain in a viable position for at least 210 days. The latter phenomenon is probably due to the membranes that cover the chondrocytes and act as an immunological barrier.

Biodegradeable temporising matrix use in a traumatic chest wound

The Welsh Centre for Burns and Plastic Surgery is responsible for a population of 10 million people in Wales and England. We describe the use of biodegradable temporising matrix (BTM) in a large traumatic chest wound in a 23-year-old woman. BTM is a synthetic dermal substitute and has been utilised to achieve soft tissue coverage in complex wounds. This wound was sustained after the patient fell from a tractor into a large silage rake, resulting in injuries to her chest and limbs. Following meticulous debridement, her resulting full thickness skin defect measured 30 × 30 cm extending from the sternal notch to the upper abdomen, with bone, muscle and breast tissue exposure. The central chest area is complex to reconstruct due to the contours of the breasts and tendency to contracture following skin graft reconstruction. We demonstrate the first reported use of BTM for breast reconstruction, as far as we are aware.