Local Delivery of Adipose Stem Cells Promotes Allograft Survival in a Rat Hind-Limb Model of Vascularized Composite Allotransplantation.

BACKGROUND: Adipose stem cells (ASCs) are a promising cell-based immunotherapy because of their minimally invasive harvest, high yield, and immunomodulatory capacity. In this study, the authors investigated the effects of local versus systemic ASC delivery on vascularized composite allotransplant survival and alloimmune regulation. METHODS: Lewis rats received hind-limb transplants from Brown Norway rats and were administered donor-derived ASCs (passage 3 or 4, 1 × 10 6 cells/rat) locally in the allograft, or contralateral limb, or systemically at postoperative day 1. Recipients were treated intraperitoneally with rabbit anti-rat lymphocyte serum on postoperative days 1 and 4 and daily tacrolimus for 21 days. Limb allografts were monitored for clinical signs of rejection. Donor cell chimerism, immune cell differentiation, and cytokine expression in recipient lymphoid organs were measured by flow cytometric analysis. The immunomodulation function of ASCs was tested by mixed lymphocyte reaction assay and ASC stimulation studies. RESULTS: Local-ASC-treated recipients achieved significant prolonged allograft survival (85.7% survived >130 days; n = 6) compared with systemic-ASC and contralateral-ASC groups. Secondary donor skin allografts transplanted to the local-ASC long-term surviving recipients accepted permanently without additional immunosuppression. The increases in donor cell chimerism and regulatory T-cells were evident in blood and draining lymph nodes of the local-ASC group. Moreover, mixed lymphocyte reaction showed that ASCs inhibited donor-specific T-cell proliferation independent of direct ASC-T-cell contact. ASCs up-regulated antiinflammatory molecules in response to cytokine stimulation in vitro. CONCLUSION: Local delivery of ASCs promoted long-term survival and modulated alloimmune responses in a full major histocompatibility complex-mismatched vascularized composite allotransplantation model and was more effective than systemic administration. CLINICAL RELEVANCE STATEMENT: ASCs are a readily available and abundant source of therapeutic cells that could decrease the amount of systemic immunosuppression required to maintain limb and face allografts.

Surgical Nipple Delay and its Expanded Indications for Nipple-sparing Mastectomy.

Necrosis of the nipple-areolar complex (NAC) or surrounding skin has been reported in 6%-30% of nipple-sparing mastectomy (NSM) patients, with higher rates associated with larger breasts, previous breast surgery, previous radiation, and active smoking. The nipple delay (ND) procedure is known to improve viability of the NAC in NSM patients with high-risk factors. Methods: A single-institution retrospective review was done of patients who underwent ND and NSM or NSM alone from 2012 to 2022. Patient demographics, risk factors, and outcomes were compared. Results: Forty-two breasts received ND-NSM and 302 breasts received NSM alone. The ND-NSM group had significantly more high-risk factors, including elevated BMI (26.3 versus 22.9; P < 0.001), elevated prior breast surgery (50% versus 25%; P < 0.001), and greater mastectomy specimen weight (646.6 versus 303.2 g; P < 0.001). ND-NSM was more likely to have undergone preparatory mammoplasty before NSM (27% versus 1%; P < 0.001). There was no delay in NSM treatment from decision to pursue NSM (P = 0.483) or difference in skin necrosis (P = 0.256), NAC necrosis (P = 0.510), hematoma (P = 0.094), seroma (P = 0.137), or infection (P = 0.437) between groups. ND-NSM and NSM patients differed in total NAC necrosis (0% versus 3%) and implant loss (0% vs 13%), but not significantly. Conclusions: We demonstrated no NAC necrosis and no significant delay of treatment in higher risk ND-NSM patients. ND may allow higher risk patients to undergo NSM with similar morbidity as lower risk patients.

Use of wound edge inversion (epibole) to generate recalcitrant and inflamed diabetic wounds.

Robust and predictive pre-clinical models of recalcitrant diabetic wounds are critical for advancing research efforts toward improving healing. Murine models have logistic and genetic benefits versus larger animals; however, native murine healing inadequately represents clinically recalcitrant wounds in humans. Furthermore, current humanization techniques employing devices, deleterious mutations or chemical agents each carry model-specific limitations. To better replicate human wounds in a mouse, we developed a novel wound-edge inversion (WEI) technique that mimics the architecture of epibole and mitigates contracture, epithelialization, and consequently wound closure. In this study, we evaluated the reliability and durability of the WEI model in wild-type and obese diabetic mice and compared to healing after (i) punch biopsy, (ii) mechanical/silicone stenting or (iii) exogenous oxidative stressors. In wild-type mice, WEI demonstrated favourable closure characteristics compared to both control and stented wounds, however, wounds progressed to closure by 4 weeks. In contrast, diabetic WEI wounds persisted for 6-10 weeks with reduced contracture and epithelialization. In both diabetic and wild-type mice, WEI sites demonstrated persistence of inflammatory populations, absence of epithelialization, and histologic presence of alpha-SMA positive granulation tissue when compared to controls. We conclude that the WEI technique is particularly valuable for modelling recalcitrant diabetic wounds with sustained inflammation and dysfunctional healing.

Evolution of the Push-2-Spin Fat Graft Processing Device: Enhancing Efficiency and Reducing Risk of Contamination.

Background: Small-volume fat graft efficiency is a critical determinant of the cost and material effectiveness of aesthetic fat grafting in the clinical space. Recent development of devices, such as the Push-2-Spin (P2S) system (Pittsburgh, PA), has improved upon the process by yielding a rapid, handheld, multi-use system to minimize operative time and mess. Objectives: In this study, the authors describe further technical innovations on the P2S prototype that improve operative ease of use, time, and safety. Methods: Abdominoplasty samples were obtained as discarded tissue. Lipoaspirate was collected utilizing a 3.0 mm liposuction cannula and processed through centrifugation (Coleman technique), gauze (telfa) rolling, mesh straining, the tabletop P2S device (prototype), or the P2S handheld (P2S-H) device. Operative processing time, spin time, oil fraction, stromal vascular fraction (SVF) yield and viability, and adipocyte viability were assessed to compare the efficacy and viability of each device/technique. Blood agar smears of lipoaspirate were performed to assess for risk of contamination. Results: The P2S-H device outperformed its prior iteration in rotary and processing speed and was significantly faster than each other technique assessed. Furthermore, the use of an inline system offered significant advantages over open-air techniques in terms of resistance to contamination. Serial use characteristics were assessed; under these conditions, oil yield as well as adipocyte and SVF number and viability was similar between all techniques. Conclusions: The technical advancements to the P2S system which enable single-unit, handheld operation significantly improve operative time and minimize space requirements. This operative quality of life improvement comes at no cost to the efficacy of oil extraction, cellular yield, or cell viability.