Faculty Bibliography

The molecular and cellular level reaches of the metabolic dysregulations that characterize diabetes are yet to be fully discovered. As mechanisms underlying management of reactive oxygen species (ROS) gain interest as crucial factors in cell integrity, questions arise about the role of redox cues in regulation and maintenance of bone marrow-derived multipotent stromal cells (BMSCs) that contribute to wound healing, particularly in diabetes. Through comparison of BMSCs from wild type and diabetic mice, with a known redox and metabolic disorder, we found that the cytoprotective Nrf2/Keap1 pathway is dysregulated and functionally insufficient in diabetic BMSCs. Nrf2 is basally active, but in chronic ROS we found irregular inhibition of Nrf2 by Keap1, altered metabolism and limited BMSC multipotency. Forced upregulation of Nrf2-directed transcription, through knockdown of Keap1, restores redox homeostasis. Normalized Nrf2/Keap1 signaling restores multipotent cell properties in diabetic BMSCs through Sox2 expression. These restored BMSCs can resume their role in regenerative tissue repair and promote healing of diabetic wounds. Knowledge of diabetes and hyperglycemia-induced deficits in BMSC regulation, and strategies to reverse them offers translational promise. Our study establishes Nrf2/Keap1 as a cytoprotective pathway, as well as a metabolic rheostat that affects cell maintenance and differentiation switches in BMSCs.

The generation of reactive oxygen species (ROS) is a hallmark of inflammatory processes, but in excess, oxidative stress is widely implicated in various pathologies such as cancer, atherosclerosis and diabetes. We have previously shown that dysfunction of the Nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/ Kelch-like erythroid cell-derived protein 1 (Keap1) signaling pathway leads to extreme ROS imbalance during cutaneous wound healing in diabetes. Since ROS levels are an important indicator of progression of wound healing, specific and accurate quantification techniques are valuable. Several in vitro assays to measure ROS in cells and tissues have been described; however, they only provide a single cumulative measurement per sample. More recently, the development of protein-based indicators and imaging modalities have allowed for unique spatiotemporal analyses. L-012 (C13H8ClN4NaO2) is a luminol derivative that can be used for both in vivo and in vitro chemiluminescent detection of ROS generated by NAPDH oxidase. L-012 emits a stronger signal than other fluorescent probes and has been shown to be both sensitive and reliable for detecting ROS. The time lapse applicability of L-012-facilitated imaging provides valuable information about inflammatory processes while reducing the need for sacrifice and overall reducing the number of study animals. Here, we describe a protocol utilizing L-012-facilitated in vivo imaging to quantify oxidative stress in a model of excisional wound healing using diabetic mice with locally dysfunctional Nrf2/Keap1.

Radiation therapy is an effective treatment strategy for many types of cancer but is limited by its side effects on normal tissues, particularly the skin, where persistent and progressive fibrotic changes occur and can impair wound healing. In this study, we attempted to mitigate the effects of irradiation on skin using a novel transcutaneous topical delivery system to locally inhibit p53 upregulated modulator of apoptosis (PUMA) gene expression with small interfering RNA (siRNA). In an isolated skin irradiation model, the dorsal skin of C57 wild-type mice was irradiated. Prior to irradiation, PUMA and nonsense siRNA were applied via a novel hydrogel formulation to dorsal skin and reapplied weekly. Skin was harvested at multiple time points to evaluate dermal siRNA penetration, mRNA expression, protein expression, dermal thickness, subcutaneous fat, stiffness, vascular hypertrophy, SCAR index, and reactive oxygen species (ROS) generation. Murine skin treated with topical PUMA siRNA via optimized hydrogel formulation demonstrated effective PUMA inhibition in irradiated tissue at 3-4 days. Tissue stiffness, dermal thickness, vascular hypertrophy, SCAR index, ROS levels, and mRNA levels of MnSOD and TGF-β were all significantly reduced with siPUMA treatment compared to nonsense controls. Subcutaneous fat area was significantly increased, and levels of SMAD3 and Phospho-SMAD3 expression were unchanged. These results show that PUMA expression can be effectively silenced in vivo using a novel hydrogel lipoplex topical delivery system. Moreover, cutaneous PUMA inhibition mitigates radiation induced changes in tissue character, restoring a near-normal phenotype independent of SMAD3 signaling.

BACKGROUND:The prevalence of Obesity along with bariatric surgery and massive weight loss requiring panniculectomy is increasing in the United States. The effect of Diabetes Mellitus (DM) on outcomes following panniculectomy remains poorly defined despite its prevalence. Our study aims to evaluate the impact of DM on complications following panniculectomy and determine risk factors for adverse events. METHODS:The American College of Surgeons National Surgical Quality Improvement (ACS NSQIP) database was used to identify patients undergoing panniculectomy between 2010 and 2015. Patients were stratified based on diabetic status. Multivariate regression was performed to control for confounders. RESULTS:Review of the database identified 7,035 eligible patients who underwent panniculectomy, out of which 770 (10.9%) were diabetic. Multivariate regression showed that DM was a significant risk factor for wound dehiscence (OR = 1.92; 95% CI: 1.41-3.15; p=0.02). Obesity was a significant risk factor for superficial (OR = 2.78; 95% CI: 1.53 - 3.69; p<0.001) and deep (OR = 1.52; 95% CI: 1.38 - 3.97; p=0.01) incisional surgical site infection (SSI). Smokers were also at an increased risk for superficial (OR = 1.42; 95% CI: 1.19 - 1.75; p=0.03) and deep (OR = 1.63; 95% CI: 1.31 - 2.22; p=0.02) incisional SSI. CONCLUSIONS:Our analysis shows that DM is an independent risk factor for wound dehiscence following panniculectomy. Obesity and smoking were significant risk factors for superficial and deep incisional SSI. These results underscore the importance of preoperative risk factor evaluation in patients undergoing panniculectomy for safe outcomes.

The unique anatomical characteristics of the forearm region make it especially popular as a free flap donor site for craniofacial soft-tissue reconstruction. The free ulnar forearm flap is less hirsute and allows for better concealment of donor site scar as compared with its radial counterpart. Despite these factors, the free radial forearm flap remains more popular among reconstructive surgeons. Through the presented case series, we hope to emphasize the versatile nature of the free ulnar forearm flap in addressing various craniofacial soft-tissue defects. Following institutional review board approval, a retrospective review of the senior authors' clinical experience performing microvascular free ulnar forearm flap reconstruction of craniofacial soft-tissue defects was performed. A total of 10 patients were identified through our review. Soft-tissue defect locations included lower eyelid (n = 2), tongue and floor of mouth (n = 2), lower lip (n = 2), palatopharyngeal area (n = 1), nose (n = 1), and palate (n = 1). Trauma was the most common defect etiology (n = 5), followed by malignancy (n = 4), and iatrogenic injury in 1 case. All patients demonstrated good aesthetic and functional outcomes related to vision, speech, and oral intake at follow-up when applicable. The free ulnar forearm flap is a versatile reconstructive option that can be used to address a wide spectrum of craniofacial soft-tissue defects and offers numerous advantages over its radial counterpart.

: The first facial transplantation in 2005 ushered in a new era in reconstructive surgery, offering new possibilities for the repair of severe disfigurements previously limited by conventional techniques. Advances in allograft design, computerized preoperative planning, surgical technique, and postoperative revisions have helped push the boundaries in this new frontier of vascularized composite allotransplantation. Over the past 12 years, 40 of these procedures have been performed across the world, offering the field the opportunity to reflect on current outcomes. Successes achieved in the brief history of facial transplantation have resulted in a new set of obstacles the field must now overcome. In this review, we aim to highlight the achievements, major challenges, and future directions of this rapidly evolving field.

BACKGROUND:Concerns exist that immediate breast reconstruction may delay adjuvant chemotherapy initiation, impacting oncologic outcomes. Here, we determine how post-operative complications impact chemotherapy timing, and identify factors associated with greater risk for delays. METHODS:Retrospective chart review identified patients undergoing immediate breast reconstruction and adjuvant chemotherapy at a single institution from 2010 to 2015. Patients were analyzed based on occurrence of post-operative complications and time to chemotherapy. RESULTS:A total of 182 patients (244 breast reconstructions) were included in the study; 210 (86%) reconstructions did not experience post-operative complications, 34 (13.9%) did. Patients who experienced post-operative complications had a higher mean age (53.6 vs. 48.1 years, p=0.002), and higher rates of diabetes (23.5% vs. 3.8%, p<0.001).The complication group had delays in initiation of chemotherapy (56 vs. 45 days, p=0.017). Only the immediate autologous reconstruction subgroup demonstrated a statistically significant delay in initiation of chemotherapy.Patients who initiated chemotherapy >48.5 days were of higher mean age (55.9 vs. 50.7 years, p=0.074), had increased rates of diabetes (36.8% vs. 6.7%, p=0.053), and immediate autologous reconstruction (31.6% vs. 0%, p=0.027). A predictive model based on these findings determined that patients with at least 1 of these 3 risk factors have a 74% chance of experiencing prolonged times to chemotherapy initiation vs. 18% without risk factors (p=0.003). CONCLUSIONS:Risk factors for delayed chemotherapy in the context of post-operative complications are age >51.7 years, diabetes, and autologous reconstruction. Reconstructive candidates who fit this profile are at highest risk and merit extra consideration and counseling.

Current pharmacologic regimens in transplantation prevent allograft rejection through systemic recipient immunosuppression but are associated with severe morbidity and mortality. The ultimate goal of transplantation is the prevention of allograft rejection while maintaining recipient immunocompetence. We hypothesized that allografts could be engineered ex vivo (after allotransplant procurement but before transplantation) by using mesenchymal stem cell-based therapy to generate localized immunomodulation without affecting systemic recipient immunocompetence. To this end, we evaluated the therapeutic efficacy of bone marrow-derived mesenchymal stem cells in vitro and activated them toward an immunomodulatory fate by priming in inflammatory or hypoxic microenvironments. Using an established rat hindlimb model for allotransplantation, we were able to significantly prolong rejection-free allograft survival with a single perioperative ex vivo infusion of bone marrow-derived mesenchymal stem cells through the allograft vasculature, in the absence of long-term pharmacologic immunosuppression. Critically, transplanted rats rejected a second, nonengineered skin graft from the same donor species to the contralateral limb at a later date, demonstrating that recipient systemic immunocompetence remained intact. This study represents a novel approach in transplant immunology and highlights the significant therapeutic opportunity of the ex vivo period in transplant engineering.

BACKGROUND: Recipient vessels proximal to the zone of injury have traditionally been preferred for lower extremity reconstruction. However, more recent data have shown mixed outcomes when performing anastomoses distal to the zone of injury. We investigated the impact of recipient vessel location on free flap outcomes. METHODS: Retrospective review (1979-2016); 312 soft tissue free flaps for open tibia fractures met inclusion criteria. Flap characteristics and perioperative outcomes were examined. Systematic review identified articles evaluating anastomosis location and flap outcomes; pooled data analysis was performed. RESULTS: = 0.39) found no difference in flap failure rates between proximal and distal groups. CONCLUSION/CONCLUSIONS: Our results are congruent with the current lower extremity literature and demonstrate no difference in perioperative complication rates between anastomoses performed proximal or distal to the zone of injury. These findings suggest that anastomotic location choice should be based primarily on recipient vessel quality/flow and ease of access/exposure rather than orientation relative to the zone of injury.