Development of a Porcine VCA Model Using an External Iliac Vessel-Based Vertical Rectus Abdominus Myocutaneous Flap.

BACKGROUND: Vascularized composite allotransplantation (VCA) involves transplanting a functional and anatomically complete tissue graft, such as a hand or face, from a deceased donor to a recipient. Although clinical VCA has resulted in successful outcomes, high rates of acute rejection and increased requirements for immunosuppression have led to significant long-term complications. Of note, immunosuppressed graft recipients are predisposed to infections, organ dysfunction, and malignancies. The long-term success of VCA grafts requires the discovery and implementation of unique approaches that avoid these complications altogether. Here, we describe our surgical technique and initial experience with a reproducible heterotopic porcine VCA model for the preclinical assessment of approaches to improve graft outcomes. METHODS: Six heterotopic porcine allogeneic vertical rectus abdominis myocutaneous flap transplants were performed using Sinclair donors and Yucatan recipients. Immunosuppressive therapy was not used. Each flap was based on the left external iliac vessel system. Animals were followed postoperatively for surgery-related complications. RESULTS: The six pigs underwent successful VCA and were euthanized at the end of the study. Each flap demonstrated complete survival following vessel anastomosis. For the allogeneic recipients, on average, minimal erythema and healthy flap color were observed from postoperative days 1 to 4. There were no surgery-related animal deaths or complications. CONCLUSION: We have developed a reproducible, technically feasible heterotopic porcine VCA model based on the left external iliac vessel system. Our results demonstrate this model's potential to improve VCA graft outcomes by exploring tolerance induction and rejection biomarker discovery in preclinical studies.

Northwestern and Other Historical Vignettes regarding the Vascular Anastomotic Coupling Device.

The vascular anastomotic coupling device is a widely used and effective aid to reconstructive microsurgery. Although there is a long history of innovators connected with this device, the current design of 6 interdigitating holes and pins was created de novo by a Northwestern medical student in 1960.

Repair of critical sized cranial defects with BMP9-transduced calvarial cells delivered in a thermoresponsive scaffold.

Large skeletal defects caused by trauma, congenital malformations, and post-oncologic resections of the calvarium present major challenges to the reconstructive surgeon. We previously identified BMP-9 as the most osteogenic BMP in vitro and in vivo. Here we sought to investigate the bone regenerative capacity of murine-derived calvarial mesenchymal progenitor cells (iCALs) transduced by BMP-9 in the context of healing critical-sized calvarial defects. To accomplish this, the transduced cells were delivered to the defect site within a thermoresponsive biodegradable scaffold consisting of poly(polyethylene glycol citrate-co-N-isopropylacrylamide mixed with gelatin (PPCN-g). A total of three treatment arms were evaluated: PPCN-g alone, PPCN-g seeded with iCALs expressing GFP, and PPCN-g seeded with iCALs expressing BMP-9. Defects treated only with PPCN-g scaffold did not statistically change in size when evaluated at eight weeks postoperatively (p = 0.72). Conversely, both animal groups treated with iCALs showed significant reductions in defect size after 12 weeks of follow-up (BMP9-treated: p = 0.0025; GFP-treated: p = 0.0042). However, H&E and trichrome staining revealed more complete osseointegration and mature bone formation only in the BMP9-treated group. These results suggest that BMP9-transduced iCALs seeded in a PPCN-g thermoresponsive scaffold is capable of inducing bone formation in vivo and is an effective means of creating tissue engineered bone for critical sized defects.

In vivo evaluation of a novel mesh suture design for abdominal wall closure.

BACKGROUND: The authors present a novel mesh suture design aimed at minimizing the early laparotomy dehiscence that drives ventral hernia formation. The authors hypothesized that modulation of the suture-tissue interface through use of a macroporous structure and increased aspect ratio (width-to-height ratio) would decrease the suture pull-through that leads to laparotomy dehiscence. METHODS: Incisional hernias were produced in 30 rats according to an established hernia model. The rat hernias were randomized to repair with either two 5-0 polypropylene sutures or two midweight polypropylene mesh sutures. Standardized photographs were taken before repair and 1 month after repair. Edge-detection software was used to define the border of the hernia defect and calculate the defect area. Histologic analysis was performed on all mesh suture specimens. RESULTS: Seventeen hernias were repaired with mesh sutures and 13 were repaired with conventional sutures. The mean area of the recurrent defects following repair with mesh suture was 177.8 ± 27.1 mm2, compared with 267.3 ± 34.1 mm2 following conventional suture repair. This correlated to a 57.4 percent reduction in defect area after mesh suture repair, compared with a 10.1 percent increase in defect area following conventional suture repair (p < 0.0007). None (zero of 34) of the mesh sutures pulled through the surrounding tissue, whereas 65 percent (17 of 26) of the conventional sutures demonstrated complete pull-through. Excellent fibrocollagenous ingrowth was observed in 13 of 17 mesh suture specimens. CONCLUSIONS: Mesh sutures better resisted suture pull-through than conventional polypropylene sutures. The design elements of mesh sutures may prevent early laparotomy dehiscence by more evenly distributing distracting forces at the suture-tissue interface and permitting tissue incorporation of the suture itself.