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Delays in treatment of burn injuries can lead to significant morbidity, loss of function, and poor aesthetic appearance. Preventing conversion from partial- to full-thickness burns may help mitigate these sequelae. The pathophysiology of burn wound conversion remains unknown, but an overactive immune response is thought to be implicated. The purpose of this study was to determine whether downregulating the immune response via tacrolimus can decrease burn wound conversion.Assembly of the microfluidic hydrogels was achieved by embedding microfibers within a hydrogel scaffold composed of a gelatin-alginate blend. Tacrolimus stock solution for intraperitoneal injection was made by re-suspending powdered tacrolimus in DMSO at 10 mg/mL. 24 young (2-4 months) and 24 old (16 months) mice were given partial thickness burns. The treatment cohort received either tacrolimus ointment with a hydrogel dressing (6 young and 6 old) or an intraperitoneal injection of a tacrolimus solution (6 young and 6 old), while the control cohort only received either only the microcapillary hydrogel dressing or an intraperitoneal injection of saline. Mice were euthanized at day 3 after injury and skin samples were taken. Burn depth was evaluated using Vimentin immunostaining.In old mice, intraperitoneal injection of tacrolimus was able to significantly reduce burn wound depth compared to intraperitoneal injection of saline (p = 0.011). Similarly in old mice, topical hydrogel with tacrolimus was able to significantly reduce burn wound depth compared to hydrogel alone (p 0.001). Topical hydrogel with tacrolimus was able to mitigate the detrimental effects of older age on wound conversion, such that burn wounds of older mice treated with tacrolimus hydrogel dressing had similar burn depths as younger mice (p = 0.240).Utilizing a combination treatment of tacrolimus and microcapillary hydrogel is able to rescue the negative effects of aging and prevent partial- to full-thickness burn wound conversion. Hopefully these findings will encourage deeper investigation into the possible therapeutic advantages of utilizing immunosuppressive agents to decrease morbidity after burn injuries. Future research will need to specifically investigate IL-2 as an inhibitory target in the acute inflammatory cascade of burn injury.

Burn injury remains a serious cause of morbidity and mortality worldwide. Severity of burns is determined by the percentage of burned area compared to the body surface area, age of patient, and by the depth of skin and soft tissue involvement; these factors determine management as well as prospective outcomes. The pathophysiology of partial- to full-thickness burn conversion remains poorly understood and is associated with a worse overall prognosis. Recent studies have demonstrated that an altered inflammatory response may play a significant role in this conversion and therefore a reduction in early inflammation is crucial to ultimately decreasing burn severity and morbidity. We hypothesize that the application of a microcapillary gelatin-alginate hydrogel loaded with anti-TNF-α (infliximab) monoclonal antibodies to a partial-thickness burn will reduce inflammation within partially burned skin and prevent further progression to a full-thickness burn.Assembly of the microfluidic hydrogels is achieved by embedding microfibers within a hydrogel scaffold composed of a gelatin-alginate blend, which is then soaked in a solution containing anti-TNF-α antibodies for drug loading. 12 young (2-4 months) and 12 old (16 months) mice were given partial thickness burns. The treatment cohort received the anti-TNF-α infused hydrogel with an occlusive dressing and the control cohort only received an occlusive dressing. Mice were euthanized at post-burn day 3 and skin samples were taken. Burn depth was evaluated using Vimentin immunostaining.All mice in the treatment cohort demonstrated decreased conversion of burn from partial to full thickness injury (old = p0.01, young = p0.001) as compared to the control group. Old mice had greater depth of burn than young mice (p0.001). There were greater eosinophils in the treatment cohort for both young and old mice, but it did not reach statistical significance.The application of a novel microcapillary gelatin-alginate hydrogel infused with anti-TNF-α antibody to partial thickness burns in mice showed reduction in partial to full thickness burn secondary progression as compared to controls using this murine model; this promising finding might help decrease the high morbidity and mortality associated with burn injuries.

Partial burn injury in older patients is associated with higher rates of morbidity, mortality, and conversion to full thickness burn (Finnerty et al., 2009; Pham et al., 2009). Both human and mouse models demonstrate an altered systemic immune response in older subjects, however less is known about the localized response (Jeschke et al., 2016; Farinas et al., 2018; Mohs et al., 2017). We hypothesized that a mouse model could demonstrate differences in the localized inflammatory response of the old.Six old (66 weeks) and young (8 weeks) mice received partial thickness thermal burns. Localized and systemic expression of nine chemokines (TNFalpha, MCP-1, MIP-2, S100A9, EGF, IL-10, RANTES, G-CSF, and EOTAXIN) were evaluated at day 3 after burn using Luminex analysis. Vimentin immunostaining was used to evaluate injury depth.Vimentin staining demonstrated increased burn depth in old mice (449±38μm) as compared to young (166±18μm) (p0.05). Both groups exhibited increased localized expression of EOTAXIN after burn (p0.05), however expression in old mice (83.6±6.1pg/ml) was lower than that of young (126.8±18.7pg/ml) (p0.05). Systemically, however, old mice had increased baseline EOTAXIN expression (1332.40±110.78pg/ml) compared to young (666.12±45.8pg/ml) (p0.005).EOTAXIN is one of the primary chemoattractants for selective eosinophilic recruitment and activation. While eosinophils are important for wound healing, a hyperactive eosinophilic response can result in tissue damage. We hypothesize that the increased baseline serum EOTAXIN in the old may prime their hyperactive response, and may contribute to their worse clinical outcomes. Long-term eosinophil activation requires further study, however our findings indicate a role for EOTAXIN and eosinophils in burn response.

Advanced age alters many physiological processes in the body, including both innate and adaptive immune responses, affecting burn wound healing. Previous findings in our lab led us to look more closely at eosinophil infiltration of burn tissues. We hypothesize that burn wounds within the older population present with an increased population of eosinophils than those in the younger population.A pilot study was performed utilizing samples collected from male and female patients 30-years-old and younger and 65-years-old and older. Samples were collected at day (PBD) 2-6 after burn. Deep partial-thickness burn tissues were collected during surgery, formalin-fixed paraffin embedded (FFPE), and assessed by HE to confirm deep partial-thickness injury. Immunohistochemistry (IHC) was then performed for Major Basic Protein (MBP) to identify eosinophils. Eosinophils/mm burn were calculated. Welch's Test was used to determine statistical significance of eosinophil measurements between young and old groups.Thirteen samples, were divided into two groups, Young (n=10) and Old (n=3). The mean and median age for Young was 23yo (Max 30yo; Min. 17yo). The mean age was 81yo and the median 84yo for the Old (Max. 93yo; Min. 67yo). Other demographics included race. It was found that the Young and Old groups had a mean of 0.171 Eos/mm and 0.910 Eos/mm, respectively, which was statistically significant (p=0.017).Older patients do present with increased eosinophil infiltration in the early stages of burn wound healing within our small sample set. Increased sample numbers will be required to confirm this discovery.

Treatment for mandibular fractures is commonly performed via open reduction fixation with mini titanium or resorbable plates and screws. The investigators hypothesized differences in maximum mechanical stress forces and deflection with each plating material; however, it was proposed that the experimental forces withstood by the resorbable system would be enough to withstand normal forces produced during mastication. The sample was composed of fresh cadaver mandibles that were harvested, fractured, and fixated with plates and screws. The predictor variable was fracture fixation and included a titanium plating or resorbable poly-L-lactide plating system. The primary outcome measure was maximum load withstood before plating failure measured in Newtons (N). Descriptive and bivariate statistics were computed, P value was set at .05. The sample was composed of six mandibles with and grouped by type of fixation modality, Titanium (T) (n = 3) and Resorbable (n = 3). There was a statistically significant correlation between the T group and increased maximum load (N) before failure as compared to the R group, (P = 0.023). The results suggest that fracture fixation with titanium plates and screws can withstand greater maximum forces before failure; however, the resorbable plating system withstood forces similar to/or greater than the maximum forces produced during normal mastication., Biomedical engineering; Dentistry; Materials science; Surgey; Resorbable plates; Titanium plates; Fracture; Fixation; Poly-l-lactic acid; Mandible.

Currently, determination of burn depth and healing outcomes has been limited to subjective assessment or a single modality, e.g., laser Doppler imaging. Such measures have proven less than ideal. Recent developments in other non-contact technologies such as optical coherence tomography (OCT) and pulse speckle imaging (PSI) offer the promise that an intelligent fusion of information across these modalities can improve visualization of burn regions thereby increasing the sensitivity of the diagnosis. In this work, we combined OCT and PSI images to classify the degree of burn (superficial, partial-thickness and full-thickness burns). Algorithms were developed to integrate and visualize skin structure (with and without burns) from the two modalities. We have completed the proposed initiatives by employing a porcine burn model and compiled results that attest to the utility of our proposed dual-modal fusion approach. Computer-derived data indicating the varying burn depths were validated through immunohistochemical analysis performed on burned skin tissue. The combined performance of OCT and PSI modalities provided an overall ROC-AUC=0.87 (significant at p

Approximately 12% of operations for traumatic neuropathy are for patients with segmental nerve loss, and less than 50% of these injuries obtain meaningful functional recovery. Polyethylene glycol (PEG) therapy has been shown to improve functional outcomes after nerve severance, and we hypothesized this therapy could also benefit nerve autografting.We used a segmental rat sciatic nerve injury model in which we repaired a 0.5-cm defect with an autograft using microsurgery. We treated experimental animals with solutions containing methylene blue (MB) and PEG; control animals did not receive PEG. We recorded compound action potentials (CAPs) before nerve transection, after solution therapy, and at 72 h postoperatively. The animals underwent behavioral testing at 24 and 72 h postoperatively. After we euthanized the animals, we fixed the nerves, sectioned and immunostained them to allow for quantitative morphometric analysis.The introduction of hydrophilic polymers greatly improved morphological and functional recovery of rat sciatic axons at 1-3 d after nerve autografting. Polyethylene glycol therapy restored CAPs in all animals, and CAPs were still present 72 h postoperatively. No CAPS were detectable in control animals. Foot Fault asymmetry scores and sciatic functional index scores were significantly improved for PEG therapy group at all time points (P0.05 and P0.001; P0.001 and P0.01). Sensory and motor axon counts were increased distally in nerves treated with PEG compared with control (P = 0.019 and P = 0.003).Polyethylene glycol therapy improves early physiologic function, behavioral outcomes, and distal axonal density after nerve autografting.

Extracellular functions of the endoplasmic reticulum chaperone protein calreticulin (CRT) are emerging. Here we show novel roles for exogenous CRT in both cutaneous wound healing and diverse processes associated with repair. Compared with platelet-derived growth factor-BB-treated controls, topical application of CRT to porcine excisional wounds enhanced the rate of wound re-epithelialization. In both normal and steroid-impaired pigs, CRT increased granulation tissue formation. Immunohistochemical analyses of the wounds 5 and 10 days after injury revealed marked up-regulation of transforming growth factor-beta3 (a key regulator of wound healing), a threefold increase in macrophage influx, and an increase in the cellular proliferation of basal keratinocytes of the new epidermis and of cells of the neodermis. In vitro studies confirmed that CRT induced a greater than twofold increase in the cellular proliferation of primary human keratinocytes, fibroblasts, and microvascular endothelial cells (with 100 pg/ml, 100 ng/ml, and 1.0 pg/ml, respectively). Moreover, using a scratch plate assay, CRT maximally induced the cellular migration of keratinocytes and fibroblasts (with 10 pg/ml and 1 ng/ml, respectively). In addition, CRT induced concentration-dependent migration of keratinocytes, fibroblasts macrophages, and monocytes in chamber assays. These in vitro bioactivities provide mechanistic support for the positive biological effects of CRT observed on both the epidermis and dermis of wounds in vivo, underscoring a significant role for CRT in the repair of cutaneous wounds.

Mechanisms that drive wound repair are complex and have challenged wound-healing investigators for many years. In this review, we present four examples of new tools that are being utilized to discover events that drive wound repair and regeneration. Laser capture microdissection facilitates the focused collection of tissue for purposes of genomic or proteomic analysis from specific cell populations within the wound bed. Tissue profiling and protein imaging by matrix-assisted laser desorption ionization mass spectrometry are two proteomic-based tools that permit rapid analysis with spatial orientation and relative abundance of hundreds to thousands of molecules from intact tissues. Another approach uses an in vivo porcine model to harness a strategy of adenoviral-driven receptor overexpression. This biological model closely mimics the human setting and permits transient stimulation along a specific cytokine pathway to tip the balance in favor of accelerated repair. The advent of new approaches that collect cell samples from within their in vivo circumstance while preserving discrete cellular localizations is likely to move the field of wound repair forward.

Purpose Polyethylene glycol (PEG) has been hypothesized to restore axonal continuity using an in vivo rat sciatic nerve injury model when nerve repair occurs within minutes after nerve injury. We hypothesized that PEG could restore axonal continuity when nerve repair was delayed. Methods The left sciatic nerves of female Sprague-Dawley rats were transected and repaired in an end-to-end fashion using standard microsurgical techniques at 3 time points (1, 8, and 24 hours) after injury. Polyethylene glycol was delivered to the neurorrhaphy in the experimental group. Post-repair compound action potentials were immediately recorded after repair. Animals underwent behavioral assessments at 3 days and 1 week after surgery using the sciatic functional index test. The animals were sacrificed at 1 week to obtain axon counts. Results The PEG-treated nerves had improved compound action potential conduction and animals treated with PEG had improved sciatic function index. Compound action potential conduction was restored in PEG-fused rats when nerves were repaired at 1, 8, and 24 hours. In the control groups, no compound action potential conduction was restored when nerves were repaired. Sciatic functional index was superior in PEG-fused rats at 3 and 7 days after surgery compared with control groups at all 3 time points of nerve repair. Distal motor and sensory axon counts were higher in the PEG-treated rats. Conclusions Polyethylene glycol fusion is a new adjunct for nerve repair that allows rapid restoration of axonal continuity. It effective when delayed nerve repair is performed. Clinical relevance Nerve repair with application of PEG is a potential therapy that may have efficacy in a clinical setting. It is an experimental therapy that needs more investigation as well as clinical trials.