Browsing by Author "Hassanein, Aladdin H."
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Item 142. Optimization of the Murine Hindlimb Lymphedema Model(Wolters Kluwer, 2025-04-24) Ahmed, Shahnur; Mohan, Ganesh; Sullivan, Steven J.; Jorge, Miguel; Sinha, Mithun; Hassanein, Aladdin H.; Surgery, School of MedicinePURPOSE: Secondary lymphedema is limb swelling from lymphatic injury. It frequently occurs following lymph node dissection and radiation during the treatment of malignancies such as breast cancer or melanoma. The murine tail is the most commonly used model to study secondary lymphedema and involves full thickness tail skin excision and lymphatic vessel disruption. The murine hindlimb model, which has been less frequently used in the literature, offers a more clinically translatable method. However, there is inconsistency and variability, including the benefit of radiation, which have contributed to the model being less widely adapted than the tail model. The purpose of this study is to 1) optimize the murine hindlimb lymphedema to achieve consistent results and 2) assess the effect of radiation on outcome in the murine hindlimb model. METHODS: C57BL/6 mice either underwent 20 Gy irradiation of one hindlimb seven days prior to surgery (n=11) or no preoperative radiation (n=9). For all mice, a circumferential skin incision was created at the proximal hindlimb exposing the subcutaneous soft tissues. Lymphatics were identified with isosulfan blue dye injection into the paw and disrupted. Popliteal lymph nodes were excised. The skin was sutured leaving a 3 mm gap. The contralateral hindlimb served as the control. Paw thickness and calf thickness measurements were obtained at weekly intervals and indocyanine green (ICG) near-infrared laser lymphangiography was used to assess lymphatic function. RESULTS: For the irradiated mice, the average paw thickness of the operated hindlimb on postoperative day (POD) 14 was 3.5±0.3 cm compared to 2.1±0.05 cm on the contralateral limb (p=0.0001). At POD-90, the average paw thickness of the irradiated, operated hindlimb was 2.4±0.1 cm compared to 2.1±0.1 cm for the contralateral limb (p=0.01). ICG lymphangiography at 24-hours postinjection on POD-42 demonstrated an average signal intensity of 97.7±28.5 arbitrary fluorescent units (AFU) in the operated hindlimb compared to 33.6±6.2 AFU in the non-operated hindlimb (p=0.003). In the mice that did not undergo radiation, the average paw thickness was 2.5±0.2 cm on POD-42 was greater than the contralateral limb (2.1±0.1 cm) (p=0.0002) but smaller than hindlimbs that underwent radiation (3.2±0.1 cm) (p=0.0002). The nonradiated mice had greater paw thickness than the contralateral control until POD-56 whereas the radiated mice sustained significant paw thickness until Day 90. CONCLUSION: Radiation of the murine hindlimb model results in sustained lymphedema compared to non-irradiated mice. The murine hindlimb lymphedema model is clinically more translatable than the murine tail model and includes limb lymphatic vessel disruption, and popliteal lymphadenectomy and ideally radiation for consistent results with lymphedema sustained for 90 days.Item 153. Quantification of Lymphangiogenesis in Murine Lymphedema Tail Model Using Intravital Microscopy(Wolters Kluwer, 2023-05-19) Mohan, Ganesh; Khan, Imran; Diaz, Stephanie M.; Neumann, Colby R.; Jorge, Miguel D.; Sinha, Mithun; Gordillo, Gayle M.; Sen, Chandan K.; Hassanein, Aladdin H.; Surgery, School of MedicinePURPOSE: Lymphedema is limb swelling caused by lymphatic dysfunction. It occurs in 30% of patients that undergo axillary lymph node dissection in the treatment of breast cancer. There is no cure for this disease. Understanding the mechanisms of lymphatic growth will play a pivotal role in developing therapeutic strategies against these conditions. Visualization of lymphangiogenesis and functional assessment remains a challenge. Intravital two-photon microscopy (IVM) is a powerful imaging tool for investigating various biological processes in live animals. Tissue nanotransfection technology (TNT) facilitates a direct, transcutaneous non-viral vector gene delivery using a chip with nanochannel poration in a rapid (<100ms) focused electric field. TNT was used in this study to deliver the genetic cargo in the murine tail lymphedema to assess the lymphangiogenesis. The purpose of this study is to experimentally evaluate the applicability of IVM to visualize and quantify lymphatics. METHODS: The murine tail model of lymphedema was utilized. A 3 mm full thickness skin excision and lymphatic vessel disruption was performed 20 mm from the base of the tail in twelve C57BL/6 mice. TNT was applied to the murine tail (day 0) directly at the surgical site with genetic cargo loaded into the TNT reservoir: Group I (control) was given pCMV6 (expression vector backbone alone) (n=6); Group II had pCMV6-Prox1 (n=6). Post-TNT (day 10), a 3 cm segment of murine tail was deskinned distal to the site of occlusion to optimize visualization. FITC-Dextran (2000 kD) injected intradermally at the distal tail region for lymphatic uptake. Lymphatic vessels are visualized at the second skin excision site with the Leica SP8 Confocal/Multiphoton Microscope and assessed for number of branching points to determine the newly formed lymphatics. Lymphatic vessel density was also observed by immunostaining with anti-Podoplanin antibody. RESULTS: The experimental group II exhibited increased branching points (3-fold) using filamentation analysis compared to control group I at the site of TNT treatment (n=6, p<0.05). Increased lymphatic vessel density was also observed with Podoplanin immunostaining post-TNT application. Intensity quantification of immunohistochemistry revealed greater expression of Podoplanin in Group II when compared to Group I (n=6, p<0.05). CONCLUSION: This study demonstrates a novel, powerful imaging tool for investigating lymphatic vessels in live murine tail model of lymphedema. Intravital microscopy can be utilized for functional assessment of lymphatics and visualization of lymphangiogenesis following gene-based therapy.Item 177. Prophylactic Absorbable Antibiotic Beads For High Risk Implant-based Reconstruction: A Single Institution Pilot Study(Wolters Kluwer, 2023-05-19) Ahmed, Shahnur; Lee, Jason T. C.; Roth, Dylan D.; Liu, Steven; Fisher, Carla S.; Fan, Betty; Imeokparia, Folasade; Ludwig, Kandice; Lester, Mary E.; Hassanein, Aladdin H.; Surgery, School of MedicinePURPOSE: Infections are problematic in implant-based reconstruction after mastectomies. Infection rates have been reported to be as high as 31%. Strategies to reduce the risk of infection include various antibiotic irrigation solutions, “no-touch” techniques, optimizing sterility, and empiric antibiotic use for skin flora coverage. Absorbable antibiotic beads have been well described for other indications, including orthopedic and pressure sore reconstruction. The purpose of this study is to evaluate the use of prophylactic biodegradable antibiotic beads during pre-pectoral and sub-pectoral implant-based breast reconstruction following mastectomy. METHODS: A single-center retrospective review of patients who underwent implant-based breast reconstruction post-mastectomy between 2019 to 2022. Patients were divided into two groups: Group I were deemed “high risk” by the senior author and received biodegradable antibiotic beads (1 gram vancomycin, 240 mg gentamicin) during tissue expander or implant reconstruction (pre-pectoral or subpectoral) while Group II (control) had no antibiotic beads. Demographic data, diabetes, body mass index (BMI), implant plane (pre-pectoral or sub-pectoral), smoking and use of mesh were recorded. Outcome variables included postoperative cellulitis or infection requiring oral or intravenous antibiotics and tissue expander loss at 90 days. RESULTS: In our study period, 19 patients (36 total implants/expanders) received biodegradable antibiotic beads during implant-based breast reconstruction (Group I). There were 174 patients (290 total expanders) who did not receive antibiotic beads (Group II). Patients in Group I had a history of previous expander/implant infection in 73.6%. Pre-pectoral placement of implants occurred in 84.2% of patients in Group I and 74.1% in Group II. Diabetes was prevalent in 15.8% of Group I compared to 5.7% seen in Group II patients. The mean BMI in Group I was 30.5 kg/m2 compared to 27.8 kg/m2 in Group II (p-value 0.88). Implant infection rate of Group I at 90 days was 8.3% (3/36 total expanders) compared to 8.6% (25/290 total expanders) in Group II. Implant loss in Group I was 5.5% (2/26 total expanders) compared to 7.6% (22/290) in Group II. CONCLUSION: The incidence of infection in high risk patients who have absorbable antibiotic beads placed during the time of reconstruction appears to be normalized to the control group in this pilot study, suggesting that absorbable antibiotic beads may decrease postoperative infection complications. Future studies may further clarify its benefit in selected groups.Item 65. Prophylactic Absorbable Antibiotic Beads: Effect on Tissue Expander Reconstruction Outcomes Following Mastectomy Skin Necrosis(Wolters Kluwer, 2025-04-24) Ahmed, Shahnur; Zaidi, Shozaf S.; Fisher, Carla S.; Ludwig, Kandice K.; Imeokparia, Folasade O.; VonDerHaar, R. Jason; Bamba, Ravinder; Danforth, Rachel M.; Hassanein, Aladdin H.; Lester, Mary E.; Surgery, School of MedicinePURPOSE: Mastectomy skin necrosis is problematic in tissue expander reconstruction with rates between 7 to 30%. Partial or full-thickness skin necrosis may harbor bacterial colonization promoting infection and risk of implant loss. Absorbable antibiotic-impregnated calcium-sulfate antibiotic beads have been described to reduce tissue expander (TE)/implant infection when used prophylactically for prepectoral breast reconstruction. The purpose of this study is to evaluate the effect of absorbable antibiotic beads on outcomes in patients who develop mastectomy skin necrosis after immediate postmastectomy tissue expander breast reconstruction. METHODS: A single-center retrospective review was performed for patients who underwent mastectomy, immediate prepectoral TE reconstruction on the same day (2018-2024). Patients who developed mastectomy skin necrosis were included. Patients were divided into two groups: Group 1 (absorbable antibiotic beads with TE placement) and Group 2 (no antibiotic beads with TE). Demographical information was recorded. Surgical-site infection (90-days) and implant removal were the outcome variables. RESULTS: The study included 61 patients (75 total breasts with necrosis) who underwent prepectoral TE breast reconstruction following mastectomy and developed mastectomy skin necrosis. The patients included in the study with mastectomy skin necrosis were 12 patients in Group 1 (16 breasts) and 49 patients in Group 2 (59 breasts). Baseline characteristics were not significantly difference between groups (p=1). There was no difference between nipple-sparing mastectomy or skin-sparing mastectomy between groups (p=0.1094). Acellular dermal matrix was used in 66.7% (8/12) of Group 1 compared to 83.7% (41/49) of Group 2 (p=0.2285). Operative management of mastectomy skin necrosis including debridement and reclosure was required in 50% (6/12) of Group 1 compared to 69.4% (34/49) of Group 2 patients (p=0.3093). There was one occurrence (6.3%, 1/16 TEs) of surgical-site infection in Group 1 and 35.6% (21/59 TEs) in Group 2 (p=0.0288). TE removal resulted in 6.3% (1/16 TEs) in Group 1 and 33.9% (20/59 TEs) in Group 2 (p=0.0310). The mean follow-up time was 189 days (range 146-236 days). CONCLUSIONS: Patients who develop mastectomy skin necrosis after prepectoral tissue expander reconstruction may experience lower rates of TE removal and infection when prophylactic absorbable antibiotic-impregnated beads are used. Patients who develop mastectomy skin necrosis are at high risk for infection and TE loss. Prophylactic antibiotic beads used at the time of mastectomy with prepectoral TE reconstruction decrease the risk of infection and TE loss in patients who experience mastectomy skin necrosis.Item 80. Lymphatic Preconditioning: Novel Investigation Of A “Lymphatic Delay Phenomenon”(Wolters Kluwer, 2024-04-19) Hulsman, Luci; Mohan, Ganesh; Ahmed, Shahnur; Jorge, Miguel D.; Sullivan, Steven J.; Mohammed, Imran; Sinha, Mithun; Hassanein, Aladdin H.; Surgery, School of MedicineBackground: The vascular delay phenomenon is a well-described concept of flap physiology with many clinical applications used to increase flap viability. The approach employs a staged surgical procedure with selective partial disruption of the flap’s blood supply to increase the robustness of the remaining blood supply, followed by interval flap transfer 7-10 days later. While this vascular delay phenomenon has been thoroughly studied, no investigation has been performed to determine if a similar “delay phenomenon” exists for lymphatic vessels. Lymphedema frequently occurs following injury of lymphatics during lymph node dissection. The purpose of this study was to evaluate whether lymphatic preconditioning with staged disruption of lymphatics can be protective against lymphedema. Methods: The standard murine tail lymphedema model was utilized which involves creating a 3 mm circumferential skin excision by the base of the tail and surgically clipping two lymphatics. This standard model was used for a control (Group 1, Control A, n=6). A second control (Group 2, Control B, n=5) had 3 mm circumferential skin excision, one tail lymphatic clipped at that level, and an immediate second hemi-circumferential skin excision on the more proximal tail with disruption of the other remaining lymphatic. Group 3 (experimental lymphatic preconditioning, n=6), had a 3 mm full thickness skin excision by the base of the tail, disruption of one tail lymphatic at that level (leaving one lymphatic vessel intact) followed by staged hemi-circumferential skin excision with disruption of the remaining lymphatic vessel 7 days later. Tail volume was assessed with tail measurements using the truncated cone equation. Immunohistochemistry and histology was sent. Results: Group 3 (experimental lymphatic preconditioning) had a change in tail volume of 79.1 mm3 compared to Group 1 (Control A) 154.6 mm3 (p=0.03) and Group 2 (Control B) 126.6 mm3 (p=0.05) at 28 days post-lymphatic injury. Conclusion: Mice that underwent lymphatic preconditioning with partial lymphatic injury followed by staged completion of lymphatic disruption 7 days later exhibited less tail swelling. This study demonstrates evidence for a novel concept of “lymphatic delay phenomenon” parallel to the well-known vascular delay phenomenon. Lymphatic preconditioning has potential translational clinical applications for protective effects to minimize lymphatic dysfunction.Item 97. Focal Gene Delivery in the Murine Lymphedema Tail Model Using Tissue Nanotransfection Technology (TNT)(Wolters Kluwer, 2022) Mohan, Ganesh; Khan, Imran; Sinha, Mithun; Gordillo, Gayle M.; Sen, Chandan K.; Hassanein, Aladdin H.; Surgery, School of MedicineBackground: Lymphedema is chronic limb swelling resulting from lymphatic dysfunction. It affects an estimated 5 million Americans. There is no cure for this disease. Experimental gene-based therapeutic approaches (e.g., using viral vectors) have had limited translational applicability. Tissue nanotransfection technology (TNT) utilizes a direct, transcutaneous non-viral vector, gene delivery using a chip with nanochannel poration in a rapid (<100ms) focused electric field. This platform technology has been used for various applications in tissue reprogramming. The ability to deliver genetic cargo at a focal, non-global site would have practical clinical potential in lymphedema treatment. The purpose of this study is to experimentally evaluate the applicability of TNT for lymphedema. Methods: The murine tail model of lymphedema was utilized. A 3 mm full thickness skin excision and lymphatic vessel disruption was performed 20 mm from the base of the tail in twelve C57BL/6 mice. TNT was applied to the murine tail (day 0) directly at the surgical site with genetic cargo loaded into the TNT reservoir: Group I (control) was given pCMV6 (expression vector backbone alone) (n=6); Group II had pCMV6-Prox1 (n=6). TNT was applied with square wave pulse electric stimulation (10x10ms pulses, 250 V, 10 mA). The efficiency of gene delivery was assessed through qRT-PCR using primers with SYBR Green fluorescence quantification and immunostaining with anti-Prox1 antibody. Results: The experimental Group II exhibited four-fold increased expression of Prox1 using qRT-PCR compared to control Group I at the site of TNT treatment (P<0.05). Increased expression of Prox1 was also observed with immunohistochemistry 3 days post-TNT application. Intensity quantification of immunohistochemistry revealed greater expression of Prox1 in Group II when compared to Group I (P<0.05). Conclusion: This study demonstrates a novel, focal nanotechnology approach for local genetic cargo delivery in murine tail lymphedema model without the use of viral vectors for transfection. TNT can rapidly and effectively be applied for potentially therapeutic delivery of factors locally at the site of lymphedema.Item A Comparative Analysis of Negative Pressure Wound Therapy Methods for Sternal Wound Infections(Wolters Kluwer, 2025-03-07) Bamba, Ravinder; Harvey, Brianna I.; Malik, Noor U.; Higgins, Jasmine; Sung, Cynthia; Corvera, Joel S.; Hartman, Brett C.; Hassanein, Aladdin H.; Lester, Mary E.; Surgery, School of MedicineSternal wound infection can be a severe complication of cardiac surgery. Multiple debridements are often necessary before definitive coverage, and negative pressure wound therapy (NPWT) is often used as a temporary dressing between debridements. NPWT with instillation and dwell (NPWT-i) has been used in many wound types including sternal wounds with success. The purpose of this study was to compare outcomes between sternal wounds managed with conventional NPWT and NPWT-i. A total of 47 patients who had sternal wound infections were managed with debridement, negative pressure therapy, and flap. Patients were divided into 2 groups based on the type of negative pressure therapy: NPWT (n = 24) and NPWT-i (n = 23). The NPWT group required 3.3 debridements per patient before flap coverage, whereas the NPWT-i group required 3.4 debridements per patient (P = 0.86). Other postoperative outcomes including seroma, hematoma, delayed wound healing, and surgical site infection were similar between the 2 groups. We found NPWT similar to NPWT-i for the number of debridements needed and outcomes in the management of sternal wound infections. NPWT-i does not replace or decrease the need for operative debridement in sternal wounds.Item A Novel Framework for Optimizing Efficiency and Education in Microsurgical Breast Reconstruction(Wolters Kluwer, 2023-11-27) Lester, Mary E.; Berns, Jessica; Dawson, Steven; Newsom, Keeley; Hartman, Brett; Hassanein, Aladdin H.; Surgery, School of MedicineDeep inferior epigastric perforator (DIEP) flaps are becoming the most frequent choice for autologous breast reconstruction. There are many benefits to DIEP flaps, but the procedures can be lengthy and have a steep learning curve. The balance of efficiency and education can be difficult to achieve. A framework was implemented to focus on both efficiency and education at each stage of the DIEP flap procedure. The author's methods to improve efficiency include a two-team approach with assigned roles for faculty and residents. The roles are consistent across the institution. Methods to enhance education include practice in a laboratory-based microsurgical training course and assigning goals for the rotation. Trainees include independent and integrated plastic surgery residents without microsurgical fellows. Bilateral DIEPs are performed with two attendings, and unilateral DIEPs, with one attending. A retrospective review identified patients undergoing DIEP flap reconstruction from 2017 to 2020. Outcome measures include operative time and complications, which are comparable to previously published data. Focusing on education allows residents to learn each stage of the case. The authors present a framework for training residents in DIEP flap reconstruction to optimize efficiency and education.Item Abstract 68: The False Positive Rate Of Transcutaneous Tissue Oximetry Alarms In Microvascular Breast Reconstruction Rises After 24 Hours(Wolters Kluwer, 2020-05-13) Tran, Phu C.; DeBrock, Will; Lester, Mary E.; Hartman, Brett C.; Socas, Juan; Hassanein, Aladdin H.; Medicine, School of MedicinePurpose: Transcutaneous tissue oximetry is widely used as an adjunct for postoperative monitoring after microvascular breast reconstruction and has been shown to improve flap salvage rates. Despite a high sensitivity at detection of postoperative vascular issues, alarms from probe malfunctions/ and or positioning can generate unnecessary nursing calls, concerns, and evaluations. The purpose of this study is to analyze the false positive rate of transcutaneous tissue oximetry monitoring over the postoperative period and assess changes in its utility over time. Methods: Consecutive patients undergoing microvascular breast reconstruction out our institution were assessed between 2017-2019. Inclusion criteria included use of transcutaneous tissue oximetry for monitoring. Variables of interest were transcutaneous tissue oximetry alarms that triggered nursing calls, flap loss, re-exploration, and salvage rates. Results: The study included 175 patients (286 flaps). The flap loss rate was 1.0% (3/175). A total of twelve patients (6.8%) required re-exploration, with a 67.0% flap salvage rate. Nine of these patients required exploration within 24 hours. The 3 takebacks after 24 hours were not for vascular compromise but were for abdominal wall hematoma, increasingly sanguineous drain output, and exam concerning for hematoma. Within the 24-hour postoperative period, 43 tissue oximetry alarms triggered nursing calls; 7 alarms (16.2%) were confirmed to be for flap issues secondary to vascular compromise. After 24 hours, 44 alarms were triggered, none of which were associated with flap compromise. The false positive rate of the alarm within 24 hours was 83.7% (36/43) compared to 100% (44/44) after 24 hours (p= 0.01). Conclusions: Transcutaneous tissue oximetry is a helpful adjunct to the clinical exam in the postoperative monitoring of flaps in microsurgical breast reconstruction. The false positive rate significantly rises after 24 hours. The benefit may not outweigh the concerns, labor, and effort that results from alarms after postoperative day 1. We recommend considering discontinuing transcutaneous tissue oximetry monitoring after 24 hours.Item ASO Author Reflections: Immediate Lymphatic Reconstruction: A Proactive Approach to Breast Cancer-Related Lymphedema(Springer, 2021-03) Cook, Julia A.; Hassanein, Aladdin H.; Surgery, School of Medicine