Faculty Bibliography

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.

Background/UNASSIGNED:Donor-specific antibodies (DSA) to human leukocyte antigen increase the risk of accelerated rejection and allograft damage and reduce the likelihood of successful transplantation. Patients with full-thickness facial burns may benefit from facial allotransplantation. However, they are at a high risk of developing DSA due to standard features of their acute care. Case Presentation/UNASSIGNED:A 41-year-old male with severe disfigurement from facial burns consented to facial allotransplantation in 2014; panel reactive antibody score was 0%. In August of 2015, a suitable donor was found. Complement-dependent cytotoxicity crossmatch was negative; flow cytometry crossmatch was positive to donor B cells. An induction immunosuppression strategy consisting of rabbit antithymocyte globulin, rituximab, tacrolimus, mycophenolate mofetil (MMF), and methylprednisolone taper was designed. Total face, scalp, eyelid, ears, and skeletal subunit allotransplantation was performed without operative, immunological, or infectious complications. Maintenance immunosuppression consists of tacrolimus, MMF, and prednisone. As of posttransplant month 24, the patient has not developed acute rejection or metabolic or infectious complications. Conclusions/UNASSIGNED:To our knowledge, this is the first report of targeted B cell agents used for induction immunosuppression in skin-containing vascularized composite tissue allotransplantation. A cautious approach is warranted, but early results are promising for reconstructive transplant candidates given the exceptionally high rate of acute rejection episodes, particularly in the first year, in this patient population.

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.

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.

: 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.

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.

Mesenchymal stem cells (MSCs) are known to both have powerful immunosuppressive properties and promote allograft tolerance. Determining the environmental oxygen tension and inflammatory conditions under which MSCs are optimally primed for this immunosuppressive function is essential to their utilization in promoting graft tolerance. Of particular interest is the mechanisms governing the interaction between MSCs and regulatory T cells (Tregs), which is relatively unknown. We performed our experiments utilizing rat bone marrow derived MSCs. We observed that priming MSCs in hypoxia promotes maintenance of stem-like characteristics, with greater expression of typical MSC cell-surface markers, increased proliferation, and maintenance of differentiation potential. Addition of autologous MSCs to CD4+/allogeneic endothelial cell (EC) co-culture increases regulatory T cell (Treg) proliferation, which is further enhanced when MSCs are primed in hypoxia. Furthermore, MSC-mediated Treg expansion does not require direct cell-cell contact. The expression of indolamine 2,3-dioxygenase, a mediator of MSC immunomodulation, increases when MSCs are primed in hypoxia, and inhibition of IDO significantly decreases the expansion of Tregs. Priming with inflammatory cytokines IFNγ and TNFα increases also expression of markers associated with MSC immunomodulatory function, but decreases MSC proliferation. The expression of IDO also increases when MSCs are primed with inflammatory cytokines. However, there is no increase in Treg expansion when MSCs are primed with IFNγ, suggesting an alternate mechanism for inflammatory-stimulated MSC immunomodulation. Overall, these results suggest that MSCs primed in hypoxia or inflammatory conditions are optimally primed for immunosuppressive function. These results provide a clearer picture of how to enhance MSC immunomodulation for clinical use.

AIMS/OBJECTIVE:Though unmitigated oxidative stress in diabetic chronic non-healing wounds poses a major therapeutic challenge, currently, there are no effective pharmacological agents. We targeted the cytoprotective Nrf2/Keap1 pathway, which is dysfunctional in diabetic skin and the regenerative environment in the diabetic wound. We assessed the efficacy of a potent Nrf2-activator, RTA 408, a semi-synthetic oleanane triterpenoid, on accelerating diabetic wound healing. METHODS:mice, we made 10mm-diameter excisional humanized wounds in dorsal skin. We administered RTA 408 formulations daily, and used ANOVA for comparison of time to closure, in vivo real-time ROS, histology, molecular changes. RESULTS:We found that RTA 408, specifically a 0.1% formulation, significantly reduced wound healing time and increased wound closure rate. While either systemic or topical administration of RTA 408 is effective, wound closure time with the latter was far superior. RTA 408-treated diabetic wounds upregulated Nrf2 and downstream antioxidant genes, and exhibited well-vascularized granulation tissue that aided in re-epithelialization. Reintroduction of redox mechanisms via RTA 408-induced Nrf2 resulted in reduction of the oxidative status of wounds, to coordinate successful wound closure. CONCLUSIONS:This preclinical study shows that promoting Nrf2-mediated antioxidant activity in the localized regenerative milieu of a diabetic wound markedly improves the molecular and cellular composition of diabetic wound beds. RTA 408 treats and corrects the irregularity in redox balance mechanisms involving Nrf2, in an avenue not explored previously for treatment of diabetic wounds and tissue regeneration. Our study supports development of RTA 408 as a therapeutic modality for chronic diabetic wounds.