Porcine Acellular Dermal Matrix for Hernia Repair in Transplant Patients.

PURPOSE: The purpose of this study was to compare clinical outcomes of incisional hernia repair in solid organ transplant patients using non-cross-linked porcine acellular dermal matrix (PADM), human derived acellular dermal matrix (HADM) and synthetic mesh. METHODS: A retrospective review of patients who underwent hernia repair with PADM after pancreas and/or renal transplant at the University of Maryland Medical Center from 2008 to 2012 was conducted. Repair type, postoperative infection, hernia recurrence, mesh removal, and length of follow-up were recorded. Results were compared with our previously published data evaluating HADM and synthetic mesh used in transplant patients between 2000 and 2005. RESULTS: Twenty-seven patients underwent ventral hernia repair with PADM, 34 patients were repaired with HADM and 26 were repaired with synthetic mesh. The rate of wound infection in those repaired with PADM, HADM, and synthetic mesh were 14.8%, 14.7%, and 65.4%, respectively. Rates of recurrence were 13.3%, 23.5%, and 76.9%, respectively. Rate of mesh removal was found to be 7.4%, 11.8%, and 69.2%, respectively. These complication rates were significantly lower in patients who received HADM or PADM compared with patients repaired with synthetic mesh (P < 0.001). There was no statistically significant difference in the outcomes between the groups repaired with HADM or PADM. CONCLUSIONS: The use of PADM for incisional hernia repair after kidney and/or pancreas transplant significantly reduces the incidence of hernia recurrence, wound infection, and need for mesh removal compared to synthetic mesh. No difference in morbidity between HADM and PADM was observed in the study population; however, longer follow-up in the PADM group is warranted.

Porcine acellular dermal matrix (PADM) vascularises after exposure in open necrotic wounds seen after complex hernia repair.

Biological alternatives to synthetic meshes are increasingly utilised in complex abdominal wall reconstruction. There is a lack of evidence demonstrating that non-cross-linked porcine acellular dermal matrix vascularizes and integrates with human tissue in suboptimal wound conditions. We aimed to evaluate these properties in Strattice™ (Life Cell Inc., Branchburg, NJ) following ventral hernia repair. A retrospective review of patients with high-risk ventral hernia repair utilising Strattice™ as an onlay after open component separation was conducted. Patients with postoperative wound exploration and exposure of the onlay were included in this review. One patient underwent punch biopsy for histological analysis. Eleven patients with wound complications necessitating postoperative debridement and exposure of Strattice™ onlay were identified. The onlay was partially debrided in two cases, and one case required complete excision. Vascularisation was clinically evident in 10 of 11 cases (91%) as demonstrated by the presence of granulation tissue and/or the ability to support a skin graft. Histological analysis of one onlay 3 months postoperatively showed neovascularisation and collagen remodelling with minimal inflammatory response. Strattice™ demonstrated resistance to rejection, ability to undergo vascularisation and incorporation into host tissues in sub-optimal wound conditions following ventral hernia repair.

On-Q ® pain pump versus epidural for postoperative analgesia in children.

PURPOSE: The On-Q(®) pain pump provides a continuous infusion of local anesthesia for management of postoperative pain. The objective of this study was to assess the efficacy and outcomes of the On-Q(®) pump compared to continuous epidural in children postoperatively. METHODS: We performed a retrospective review of patients in our hospital who received a postoperative epidural or On-Q(®) pump from 2005 to 2008. Patients were sub-categorized by incision type. RESULTS: Seventy patients received epidural and 66 On-Q(®). On-Q(®) therapy was longer by 1 day (p < 0.0001), but did not affect postoperative length of stay. Patients with On-Q(®) pumps had a decreased rate of Foley catheter placement (p = 0.002) and shorter duration of catheter use by more than a day (p < 0.001). Moderate to severe pain was similar in the two groups on postoperative days 0-5. Supplemental narcotic use was higher in the On-Q(®) group only on postoperative day 1 (p = 0.005) and in patients with midline and transverse abdominal incisions. No differences were seen in time to ambulation or recovery of postoperative ileus. CONCLUSION: The On-Q(®) pain pump is an effective method for postoperative pain control, without the inherent risks of epidural catheters.

Surgical management of craniofacial neurofibromatosis type 1 associated tumors.

Neurofibromatosis type 1 is a rare, autosomal dominant disorder than can present with varying degrees of disfigurement depending on the associated tumor extent and location. Surgical resection is considered the most effective management of these typically benign tumors, indicated when symptoms include pain, extreme deformity, or interference with normal physical function. Giant tumors of the craniofacial region present particular difficulty due to the size of the post-resection wound deficit and the high risk surgery poses to function such as vision and facial animation in this region. Strategies of management are discussed.

Mesenchymal-specific inhibition of vascular endothelial growth factor (VEGF) attenuates growth in neonatal mice.

BACKGROUND: Vascular endothelial growth factor (VEGF) is a key mediator of angiogenesis and vasculogenesis. However, the role of VEGF in the regulation of neonatal mouse development is not completely defined. We sought to determine the effect of VEGF inhibition on the development of the neonatal mouse using a transgenic approach. MATERIALS AND METHODS: We generated triple transgenic mice that express the soluble VEGF receptor, (sFlt-1), specifically in the mesenchyme (dermo-1(Cre)- tetracycline reverse transcriptional activator (rtTA)(flox/flox)-tet(0)-sflt-1). Mothers of the pups (transgenic and littermate controls) were fed doxycycline chow at birth for transgene activation via breast milk, and the pups were sacrificed at various time points. To test reversibility of the phenotype, mice from both groups (n = 6) were switched to normal chow at P50 and monthly weights were measured for 9 mo. RESULTS: Dermo-1(Cre)-rtTA(flox/flox)-tet(0)-sflt-1 mice were smaller compared with littermate controls at P21. There was a significant reduction in tissue VEGF levels following sFlt-1 expression. The rate of growth was reduced but did not impact overall survival after 1 y. A significant reduction in organ size as a percentage body weight was seen in the kidney and stomach, whereas the weight of the colon and spleen were relatively increased; however, no gross histologic difference was observed. After 6 mo on normal diet, the dermo-1(Cre)-rtTA(flox/flox)-tet(0)-sflt-1 mouse's weight doubled, indicating reversibility of phenotype. CONCLUSION: Mesenchymal-specific inhibition of VEGF in neonatal mice results in a severe but reversible arrest in somatic growth that does not affect overall survival at 1 yr. This mouse is a useful tool to test the function of VEGF in somatic growth.

Murine tissue-engineered stomach demonstrates epithelial differentiation.

BACKGROUND: Gastric cancer remains the second largest cause of cancer-related mortality worldwide. Postgastrectomy morbidity is considerable and quality of life is poor. Tissue-engineered stomach is a potential replacement solution to restore adequate food reservoir and gastric physiology. In this study, we performed a detailed investigation of the development of tissue-engineered stomach in a mouse model, specifically evaluating epithelial differentiation, proliferation, and the presence of putative stem cell markers. MATERIALS AND METHODS: Organoid units were isolated from <3 wk-old mouse glandular stomach and seeded onto biodegradable scaffolds. The constructs were implanted into the omentum of adult mice. Implants were harvested at designated time points and analyzed with histology and immunohistochemistry. RESULTS: Tissue-engineered stomach grows as an expanding sphere with a simple columnar epithelium organized into gastric glands and an adjacent muscularis. The regenerated gastric epithelium demonstrates differentiation of all four cell types: mucous, enteroendocrine, chief, and parietal cells. Tissue-engineered stomach epithelium proliferates at a rate comparable to native glandular stomach and expresses two putative stem cell markers: DCAMKL-1 and Lgr5. CONCLUSIONS: This study demonstrates the successful generation of tissue-engineered stomach in a mouse model for the first time. Regenerated gastric epithelium is able to appropriately proliferate and differentiate. The generation of murine tissue-engineered stomach is a necessary advance as it provides the transgenic tools required to investigate the molecular and cellular mechanisms of this regenerative process. Delineating the mechanism of how tissue-engineered stomach develops in vivo is an important precursor to its use as a human stomach replacement therapy.

Electrospinning collagen and elastin: preliminary vascular tissue engineering.

Significant challenges must be overcome before the true benefit and economic impact of vascular tissue engineering can be fully realized. Toward that end, we have pioneered the electrospinning of micro- and nano-fibrous scaffoldings from the natural polymers collagen and elastin and applied these to development of biomimicking vascular tissue engineered constructs. The vascular wall composition and structure is highly intricate and imparts unique biomechanical properties that challenge the development of a living tissue engineered vascular replacement that can withstand the high pressure and pulsatile environment of the bloodstream. The potential of the novel scaffold presented here for the development of a viable vascular prosthetic meets these stringent requirements in that it can replicate the complex architecture of the blood vessel wall. This replication potential creates an "ideal" environment for subsequent in vitro development of a vascular replacement. The research presented herein provides preliminary data toward the development of electrospun collagen and elastin tissue engineering scaffolds for the development of a three layer vascular construct.

Electrospinning of poly(ethylene-co-vinyl alcohol) fibers.

Solutions of poly(ethylene-co-vinyl alcohol) or EVOH, ranging in composition from 56 to 71 wt% vinyl alcohol, can be readily electrospun at room temperature from solutions in 70% 2-propanol/water (rubbing alcohol). The solutions are prepared at 80 degrees C and allowed to cool to room temperature. Interestingly, the solutions are not stable at room temperature and eventually the polymer precipitates after several hours. However, prior to precipitation, electrospinning is extensive and rapid, allowing coverage of fibers on various substrates, including a grounded metal plate, dielectrics interposed between the charged jet and the metal ground, and on the human body. Fiber diameters of ca. 0.2-8.0 microm were obtained depending upon the solution concentration, an attractive range for tissue engineering, wound healing, and related applications. Electrospun EVOH mats have been shown to support the culturing of smooth muscle cells and fibroblasts.

Utilization of Near-infrared Indocyanine Green Angiography for Immediate and Delayed Venous Outflow Assessment in Breast Reconstruction: A Case Report.

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Mental and physical impact of body contouring procedures on post-bariatric surgery patients.

OBJECTIVE: The rapid rate of weight loss following bariatric surgery leads to areas of excessive skin that can cause physical ailments and distortion of body image. Dissatisfaction with the excessive skin can lead patients to seek plastic surgery. This study aims to assess the changes in mental and physical quality of life after body contouring procedures in the post-bariatric surgery population. METHODS: In this cross-sectional study, the 36-Item Short Form Health Survey was given to 104 patients divided into 4 groups consisting of a control group, obese patients, post-bariatric surgery patients, and post-bariatric and -body contouring surgery patients. Scores from each survey question were individually averaged, scaled, and converted to the corresponding 8 scales that make up the 36-Item Short Form Health Survey. Scale comparisons were accomplished by analysis of variance and t test. RESULTS: Compared with the obese group, both post-bariatric surgery patients and post-body contouring surgery patients had improved quality of life. When comparing the post-body contouring and post-bariatric surgery patients, the post-body contouring group did not show significant quality of life improvement and actually scored significantly lower in 2 measures, Role Emotional and Social Functioning, indicating a decreased mental component of quality of life. When compared with the control group, the post-body contouring surgery group had statistically significant lower scores in 6 of the 8 scales. CONCLUSIONS: The functional impairment caused by excessive skin following massive weight loss interferes with quality of life. Patients electing to have body contouring after bariatric surgery show decreased quality of life even after plastic surgery compared to those patients who do not.

Prognostication for body contouring surgery after bariatric surgery.

OBJECTIVE: Body contouring surgery has become a steadily increasing part of weight loss treatment in the population of patients electing to undergo bariatric surgery. This study aims to elicit factors that can be used to prognosticate which bariatric surgery patients will choose to undergo body contouring procedures. METHODS: A database of 381 patients who underwent gastric bypass surgery between August 2002 and December 2005 was retrospectively reviewed. All patients with subsequent body contouring surgery (group I) were identified and compared with those without it (group II). Variables studied were age, gender, preoperative excess body weight, percent excess weight loss at 6 and 12 months, preoperative body mass index, and change in body mass index at 6 and 12 months. RESULTS: We identified 24 patients for group I and 168 patients for group II. Group I was significantly younger with a mean age of 36 ± 9 years than group II with a mean age of 41 ± 10 years (P = .023). Change in body mass index was significantly greater in group I with changes of 16.1 ± 4 and 13.82 ± 3 (P = .001) at 6 months and changes of 21.4 ± 6.6 and 17.39 ± 4.6 (P < .0001) at 12 months in group I and group II, respectively. Lastly, the percent excess weight loss at 12 months was significantly greater in group I with a mean percent excess weight loss of 70.1 ± 13.3 than in group II with a mean percent excess weight loss of 62 ± 16.6 (P = .0052). CONCLUSIONS: Age, change in body mass index at 6 and 12 months, and percent excess weight loss at 12 month follow-up were useful predictive factors to determine which bariatric surgery patients ultimately underwent body contouring procedures.

A multicellular approach forms a significant amount of tissue-engineered small intestine in the mouse.

Tissue-engineered small intestine (TESI) has successfully been used to rescue Lewis rats after massive small bowel resection. In this study, we transitioned the technique to a mouse model, allowing investigation of the processes involved during TESI formation through the transgenic tools available in this species. This is a necessary step toward applying the technique to human therapy. Multicellular organoid units were derived from small intestines of transgenic mice and transplanted within the abdomen on biodegradable polymers. Immunofluorescence staining was used to characterize the cellular processes during TESI formation. We demonstrate the preservation of Lgr5- and DcamKl1-positive cells, two putative intestinal stem cell populations, in proximity to their niche mesenchymal cells, the intestinal subepithelial myofibroblasts (ISEMFs), at the time of implantation. Maintenance of the relationship between ISEMF and crypt epithelium is observed during the growth of TESI. The engineered small intestine has an epithelium containing a differentiated epithelium next to an innervated muscularis. Lineage tracing demonstrates that all the essential components, including epithelium, muscularis, nerves, and some of the blood vessels, are of donor origin. This multicellular approach provides the necessary cell population to regenerate large amounts of intestinal tissue that could be used to treat short bowel syndrome.

VEGF optimizes the formation of tissue-engineered small intestine.

AIM: To determine the effect of VEGF overexpression on tissue-engineered small intestine (TESI) formation. MATERIALS & METHODS: Organoid units were isolated from the intestines of 2-week-old transgenic mouse pups capable of inducible, ubiquitous VEGF overexpression (CMV-Cre/rtTA/tet(0)-VEGF) and implanted into nonobese diabetic/severe combined immunodeficiency mice. Resulting TESI were explanted at 2 and 4 weeks, and studied by histology, tissue ELISA and immunofluorescence. RESULTS: At 2 weeks postimplantation, the TESI mucosa from the VEGF overexpression group formed rudimentary villi and more crypts compared with controls, which demonstrated a flat epithelium with few crypts and no villi. At 4 weeks postimplantation, the TESI from the VEGF overexpression group was larger and significantly heavier than controls. Within the mucosa, the villus height and crypt depth was significantly longer, contained a greater percentage of proliferating crypt epithelial cells and consisted of all four terminally differentiated epithelial cell types. There was also a significant increase in the capillary density within the submucosa. CONCLUSIONS: Overexpression of VEGF optimizes the formation of TESI by increasing the submucosal capillary density, crypt epithelial proliferation and the rate of mucosa formation. A larger construct with increased villus and crypt height was noted after 4 weeks in vivo.

Electrospinning of collagen nanofibers.

Electrospinning is a fabrication process that uses an electric field to control the deposition of polymer fibers onto a target substrate. This electrostatic processing strategy can be used to fabricate fibrous polymer mats composed of fiber diameters ranging from several microns down to 100 nm or less. In this study, we describe how electrospinning can be adapted to produce tissue-engineering scaffolds composed of collagen nanofibers. Optimizing conditions for calfskin type I collagen produced a matrix composed of 100 nm fibers that exhibited the 67 nm banding pattern that is characteristic of native collagen. The structural properties of electrospun collagen varied with the tissue of origin (type I from skin vs type I from placenta), the isotype (type I vs type III), and the concentration of the collagen solution used to spin the fibers. Electrospinning is a rapid and efficient process that can be used to selectively deposit polymers in a random fashion or along a predetermined and defined axis. Toward that end, our experiments demonstrate that it is possible to tailor subtle mechanical properties into a matrix by controlling fiber orientation. The inherent properties of the electrospinning process make it possible to fabricate complex, and seamless, three-dimensional shapes. Electrospun collagen promotes cell growth and the penetration of cells into the engineered matrix. The structural, material, and biological properties of electrospun collagen suggest that this material may represent a nearly ideal tissue engineering scaffold.