Chronic wounds have a detrimental impact on patient quality of life, a significant economic cost, and often lead to severe outcomes such as amputation, sepsis or death. The elaborate interplay between bacteria, cutaneous cells, immune cells, growth factors, and proteases in chronic wounds has complicated the development of new therapies that could improve outcomes for chronic wound patients. Existing in vitro models of chronic wounds do not appreciably mimic the complexity of the wound environment. In this work, tissue-engineered skin was developed with the goal of creating an in vitro platform appropriate for testing potential clinical therapies for chronic wounds. The Lumen-X, a digital light processing bioprinter, was used to create tissue-engineered skin from a 7.5% (w/v) gelatin methacryloyl hydrogel laden with primary dermal fibroblasts. This dermal layer was developed with an emphasis on providing a favourable microenvironment for the fibroblasts in order to mimic their in vivo phenotype. An epidermal layer of human keratinocytes was formed on the hydrogel surface and stratified through culture at the air-liquid-interface. The maturation of the epidermis was thoroughly characterized with histology, immunohistochemistry, and trans-epithelial electrical resistance analyses which showed a degree of maturation suitable for wound healing studies. To verify the suitability of this tissue-engineered skin for studying healing in vitro, sharp tweezers were used to create physical wounds in the epidermis which were then infected with Pseudomonas aeruginosa. Reepithelialisation, the production of the pro- inflammatory cytokine TNF-α, and the presence of bacteria were monitored over time, showing healing in wounds without infection and those treated with antibiotics, and potential biofilm formation in infected wounds. The tissue-engineered skin developed here is suitable for use as an in vitro model of the infected chronic wound environment. Future work includes developing better methods for creating the physical wound and characterizing the bacterial biofilm in order to improve the reproducibility and clarity of results. Such a model will then be well-poised to begin testing potential chronic wound therapies in vitro. / Graduate / 2023-07-26

yes / Purpose.: The aim of this work was to develop an in vitro cornea model to study the effect of proinflammatory cytokines on wound healing. Methods.: Initial studies investigated how to maintain the ex vivo models for up to 4 weeks without loss of epithelium. To study the effect of cytokines, corneas were cultured with the interleukins IL-17A, IL-22, or a combination of IL-17A and IL-22, or lipopolysaccharide (LPS). The effect of IL-17A on wound healing was then examined. Results.: With static culture conditions, organ cultures deteriorated within 2 weeks. With gentle rocking of media over the corneas and carbon dioxide perfusion, the ex vivo models survived for up to 4 weeks without loss of epithelium. The cytokine that caused the most damage to the cornea was IL-17A. Under static conditions, wound healing of the central corneal epithelium occurred within 9 days, but only a single-layered epithelium formed whether the cornea was exposed to IL-17A or not. With rocking of media gently over the corneas, a multilayered epithelium was achieved 9 days after wounding. In the presence of IL-17A, however, there was no wound healing evident. Characterization of the cells showed that wherever epithelium was present, both differentiated cells and highly proliferative cells were present. Conclusions.: We propose that introducing rocking to extend the effective working life of this model and the introduction of IL-17A to this model to induce aspects of inflammation extend its usefulness to study the effects of agents that influence corneal regeneration under normal and inflamed conditions.

Our objective was to compare cefazolin concentrations in biopsied tissue samples collected from surgically created wounds treated with negative pressure wound therapy to those collected from surgically created wounds treated with nonadherent dressings. The study design was a prospective, controlled, experimental study. The animal population included 12 female spayed beagles. We hypothesized there would be a difference between the cefazolin concentrations of wounds treated with negative pressure wound therapy when compared to the cefazolin concentrations of wounds treated with nonadherent dressings. Surgical methods were as follows: Full thickness cutaneous wounds were created on each antebrachium (n=24). Following surgery, cefazolin (22 mg/kg) was administered intravenously to each of the dogs and continued every 8 hours during the study. The right wound was randomly assigned to group I or group II while the wound on the contralateral antebrachium was assigned to the other group. Group I wounds were treated with negative pressure wound therapy (NPWT) and group II wounds were treated with nonadherent dressings for 3 days. Dressings were changed and tissue biopsies obtained from wound beds at 24-hour intervals for both groups. Cefazolin wound tissue and plasma concentrations were measured by liquid chromatography mass spectrometry (LC-MS/MS). Blood samples for measuring plasma cefazolin concentrations were collected prior to biopsy sampling. At the time of surgery and at each bandage change, wound beds were swabbed and submitted for aerobic and anaerobic culture. Our results revealed that after initiating cefazolin treatment, wound tissue antibiotic concentrations between treatment groups were not significantly different at any sampling time. Similarly, after initiating cefazolin treatment, plasma cefazolin concentrations were not significantly different at any sampling time for individual dogs. We concluded that using a canine experimental model, NPWT treatment of surgically created wounds does not statistically impact cefazolin tissue concentrations when compared to conventional nonadherent bandage therapy / Master of Science

This study compared the effects of urinary diversion by tube cystostomy catheterization, urethral catheterization and tube cystostomy and urethral catheterization on healing urethral anastomoses in the canine urethra. Fifteen intact, mature males were divided into three groups of five dogs. Urodynamic studies were performed under halothane anesthesia preoperatively and at ten weeks postoperatively. Urethral anastomosis was performed in all dogs over a urethral catheter with 4-0 polyglyconate. Group U dogs (n=5) received transurethral catheters. Group C dogs (n=5) received tube cystostomy catheters, and Group B dogs (n=5 ) had both a transurethral catheter and a cystostomy tube placed. All dogs had catheters maintained with a closed urine collection system for seven days. Dogs were observed for ten weeks following surgery, and urinalysis and urine cultures were performed on weeks 1, 4, and 8. Preoperative evaluations were repeated ten weeks postoperatively just prior to termination of the study. Radiographic and histopathologic evaluation of the urethral specimen was performed. No significant differences among the groups were noted after the second postoperative week when comparing observation scores for urination and posturing. Measurements made on in-vivo and in-vitro urethrographic studies revealed less luminal reduction at the anastomotic site in Group C when compared to Groups B and U. Results of this study indicated that urinary diversion by tube cystostomy will minimize the percent luminal diameter reduction (PLDR) when compared to transurethral catheterization alone and tube cystostomy combined with transurethral catheterization. The author recommends tube cystostomy be considered for urinary diversion following primary closure of urethral defects due to the ease of maintenance and increased patient tolerance of the technique. / Master of Science

No / It is now recognised that psychosocial factors – anxiety and depression, social isolation, low economic status and pain, for example – are associated with delayed healing of wounds. However, little research has been undertaken to examine how these factors may not only be a consequence of delayed healing, but may also play an important role in delaying healing. It is suggested that an evaluation of a patient’s psychosocial status should therefore be included as part of a general wound assessment.

No / Knowledge of clinically and cost-effective wound management is an obvious requirement for surgeons, yet wound care education rarely features within the medical curriculum. As a result surgical trainees are often poorly placed to join in multidisciplinary wound management and may feel threatened when asked to manage wound complications. A vast range of dressing products exists yet robust evidence of the function and effectiveness of individual products is often lacking. An understanding of wound pathophysiology, a defined treatment goal and regular wound assessment combined with knowledge of basic wound dressing categories will provide guidance on product selection for different clinical situations and wound types.

No / Knowledge of clinically and cost-effective wound management is an obvious requirement for surgeons, yet wound care education rarely features within the medical curriculum. As a result surgical trainees are often poorly placed to join in multidisciplinary wound management and may feel threatened when asked to manage wound complications. A vast range of dressing products exists yet robust evidence of the function and effectiveness of individual products is often lacking. An understanding of wound pathophysiology, a defined treatment goal and regular wound assessment combined with knowledge of basic wound dressing categories will provide guidance on product selection for different clinical situations and wound types.

Spinneret based Tunable Engineered Parameters (STEP) Platform is a recently reported pseudo-dry spinning and non-electrospinning technique that allows for the deposition of aligned polymeric nano-fibers with control on fiber diameters and orientation in single and multiple layers (diameter: sub 100nm micron, length: mm-cm), deposition (parallelism 2.5 degrees) and spacing (microns)). A wide range of polymers such as PLGA, PLA, PS, and PU have been utilized for their unique material properties in scaffold design. In this thesis two unique bioscaffolds are demonstrated for the measurement of group cell migration for wound closure and single cell contractility force for the study of force modulation. The wound healing assay bridges the gap between confluent reservoirs of NIH3T3 fibroblasts through arrangement of a suspended array of fibers guiding group cell migration along the fiber axis. This platform demonstrates that topographical and geometrical features of suspended fibers play a very important role in wound closure. Spacing, alignment and orientation were optimized to shown an increased rate of closure. In the second complementary assay, we report a fused-fiber network of suspended fibers capable of measuring single cell forces. Results from our experiments demonstrate that force behavior is dependent on mechanical properties such as stiffness and geometry of fiber networks. We also demonstrate changes in spatial and temporal organization of focal adhesion zyxin in response to single cell migration on these networks. / Master of Science

The objective of this study was to determine if topical antimicrobials silver sulfadiazine and povidone-iodine ointment increase rates of healing of equine distal limb wounds that heal by second intention. Second, to determine the effect of bandaging with these topical antimicrobials. Six healthy adult horses were used to create thirty-six, 2.5 cm2 standardized full-thickness metacarpal/tarsal skin wounds. Each wound was exposed to a single treatment: 1.0 % silver sulfadiazine cream bandaged (SSD-B), 1.0 % silver sulfadiazine slow release matrix bandaged (SDX-B), 1.0% silver sulfadiazine slow release matrix not bandaged (SDX-NB), povidone-iodine ointment bandaged (PI-B), untreated control bandaged (C-B) and untreated control not bandaged (C-NB) until healing. Wound area, granulation tissue area and perimeter were measured with planimetry software from digital images obtained at each observation. Exuberant granulation tissue was excised when present. The days until healing, rate of healing parameter, rates of contraction and epithelialization were compared among groups using pair-wise analysis of least square means. The healing parameters and mean days to healing did not statistically differ between groups. Analysis of percent wound contraction and rate of epithelialization between groups was similar. Mean number of days to healing ranged from 83 (PI-B and C-B) to101 (SSD-B). All bandaged wounds produced exuberant granulation tissue requiring excision compared to none of the unbandaged. The identified rates of epithelialization and wound contraction found insignificant differences between antimicrobial treated versus untreated wounds. Similarly, rates of epithelialization and wound contraction found insignificant differences between bandaged versus unbandaged wounds. Topical povidone-iodine and silver sulfadiazine did not increase rates of healing under bandage. The 1.0% silver sulfadiazine slow release matrix not bandaged (SDX-NB) adhered well to dry wounds. Silver sulfadiazine slow-release matrix provides does not impede wound healing and provides good adherence to dry wounds not amenable to bandaging. / Master of Science

The skin is a large organ consisting of different types of tissues. It serves many important functions such as protection against microorganisms, viruses, and harmful UV rays from the sun. Additionally, the skin plays a crucial role in regulating body temperature. It is composed of three layers: the epidermis, dermis, and subcutis. When injured, blood vessels in the dermis are penetrated, resulting in bleeding. Wound healing occurs through a process divided into four phases aimed at tissue repair. Honey has long been used for its health-promoting properties, especially in wound healing, although the molecular mechanisms underlying these properties remain unclear. To contribute to a better understanding of this, this literature review examines the effects of manuka honey on various types of wounds and aims to answer whether manuka honey works better compared to standard treatments for certain wound types. This work compiled results from randomized controlled trials retrieved from the PubMed database in 2024 using the search terms "manuka honey, wound healing." The five selected studies examined the effect of manuka honey on different types of wounds (diabetic foot ulcers, leg ulcers, wounds after tooth or nail extraction, and venous ulcers) compared to standard treatments such as dressings or placebos. The studies included participants from various countries and age groups. Exclusion criteria included age under 16 years, serious illnesses, honey allergies, and ongoing steroid or anti-inflammatory treatments. The results indicated that manuka honey improved healing time for certain wound types, such as neuropathic diabetic foot ulcers and post-tooth extraction wounds and contributed to changes in bacterial flora for venous leg ulcers. Despite these promising results, the studies showed no advantage of manuka honey dressings over paraffin dressings for postoperative and venous ulcers after longer treatment durations.