Allie M. Sohn

Therapeutic delivery of hydrogen sulfide for salvage of ischemic skeletal muscle after the onset of critical ischemia

BACKGROUND Recent evidence suggests that hydrogen sulfide is capable of mitigating the degree of cellular damage associated with ischemia-reperfusion injury (IRI). METHODS This study evaluated the potential utility of hydrogen sulfide in preventing IRI in skeletal muscle by using in vitro (cultured myotubes subjected to sequential hypoxia and normoxia) and in vivo (mouse hind limb ischemia, followed by reperfusion) models to determine whether intravenous hydrogen sulfide delivered after the ischemic event had occurred (pharmacologic postconditioning) conferred protection against IRI. Injury score and apoptotic index were determined by analysis of specimens stained with hematoxylin and eosin and terminal deoxynucleotide transferase-mediated deoxy-uridine triphosphate nick-end labeling, respectively. RESULTS In vitro, hydrogen sulfide reduced the apoptotic index after 1, 3, or 5 hours of hypoxia by as much as 75% (P = .002), 80% (P = .006), and 83% (P < .001), respectively. In vivo, hydrogen sulfide delivered after the onset of hind limb ischemia and before reperfusion resulted in protection against IRI-induced cellular changes, which was validated by significant decreases in the injury score and apoptotic index. The timing of hydrogen sulfide delivery was crucial: when delivered 20 minutes before reperfusion, hydrogen sulfide conferred significant cytoprotection (P < .001), but treatment 1 minute before reperfusion did not provide protection (P = NS). CONCLUSIONS These findings confirm that hydrogen sulfide limits IRI-induced cellular damage in myotubes and skeletal muscle, even when delivered after the onset of ischemia in this murine model. These data suggest that when given in the appropriate dose and within the proper time frame, hydrogen sulfide may have significant therapeutic applications in multiple clinical scenarios.

A portable high-intensity focused ultrasound device for noninvasive venous ablation

BACKGROUND Varicose veins and other vascular abnormalities are common clinical entities. Treatment options include vein stripping, sclerotherapy, and endovenous laser treatment, but all involve some degree of invasive intervention. The purpose of this study was to determine ex vivo the effectiveness of a novel hand-held, battery-operated, high-intensity focused ultrasound (HIFU) device for transcutaneous venous ablation. METHODS The ultrasound device is 14 x 9 x 4 cm, weighs 650 g, and is powered by 4 lithium ion battery packs. An ex vivo testing platform consisting of two different models comprised of sequentially layered skin-muscle-vein or skin-fat-vein was developed, and specimens were treated with HIFU. The tissues were then disassembled, imaged, and processed for histology. The luminal cross-sectional area of vein that had been treated with HIFU and nontreated controls were measured, and the values presented as median and interquartile range (IQR). The values were compared using a Wilcoxon rank-sum test, and statistical significance was set at P < .05. RESULTS On gross and histologic examination, veins that had been treated with HIFU showed evidence of coagulation necrosis. The surface of the muscle in direct contact with the vein had a pinpoint area of coagulation, whereas the adjacent fat appeared undisturbed; the skin, fat, and the surface of the muscle in contact with the transducer remained completely unaffected. The cross-sectional area was 3.79 mm(2) (IQR, 3.38-4.22) of the control vein lumen and 0.16 mm(2) (IQR, 0.04-0.39) in those that had been treated with HIFU (P = .0304). CONCLUSION This inexpensive, portable HIFU device has the potential to allow clinicians to easily perform venous ablation in a manner that is entirely noninvasive and without the expense or inconvenience of large, complicated devices. This device represents a significant step forward in the development of new applications for HIFU technology.

Hydrogen sulfide attenuates intestinal ischemia-reperfusion injury when delivered in the post-ischemic period

Background and Aim:  To investigate whether pharmacologic post‐conditioning of intestinal tissue with hydrogen sulfide (HS) protects against ischemia reperfusion injury (IRI).

Development of an acellular bioengineered matrix with a dominant vascular pedicle.

BACKGROUND This study assessed the feasibility of creating a tissue engineering platform by decellularization of fasciocutaneous tissue. MATERIALS AND METHODS A fasciocutaneous flap based upon the superficial inferior epigastric artery was harvested from the abdominal wall of 8-wk-old male Sprague-Dawley rats. All cellular components were removed by sequential treatment with sodium azide, DNAse, and sodium deoxycholate. The degree of decellularization was qualitatively assessed by histology and quantitatively assessed by spectrophotometry. Persistence of relevant extracellular matrix proteins was shown following staining with orcein and hematoxylin. The duration of circuit patency was determined by continuous perfusion with a peristaltic perfusion pump. RESULTS Gross and histologic examination demonstrated removal of cellular constituents with preservation of tissue matrix architecture, including macrochannels and microchannels. This was confirmed by the application of spectrophotometry to DNA isolates, which showed that the decellularized flap retained 4.04 ng/μL DNA, compared with the non-processed control, which retained 37.03 ng/μL DNA, and the acellular control, which was read as having 0.65 ng/μL DNA. The extracellular matrix of vessel walls was shown to remain intact. Peristaltic perfusion of the cannulated pedicle inflow channel with phosphate buffered saline at a rate of 200 μL/min confirmed circuit patency for 6 h. CONCLUSION Fasciocutaneous flaps harvested with an intact vascular pedicle and associated tissue vascular network can be successfully decellularized and perfused ex vivo. This methodology, which is scalable to human size tissues, provides promise as a technique for the production of customizable engineered tissues.

Use of Integra and interval brachytherapy in a 2-stage auricular reconstruction after excision of a recurrent keloid.

Abstract Keloids present a formidable clinical challenge. Surgical excision in conjunction with radiation therapy may decrease the chance of keloid recurrence. Split-thickness skin grafts, however, are more prone to failure in the setting of radiation. In this report, we present a patient with a recurrent auricular keloid who underwent excision and immediate Integra (Integra LifeSciences, Plainsboro, NJ) application, followed by high–dose rate brachytherapy and interval split-thickness skin graft placement. A 23-year-old woman with a history of a recurrent auricular keloid after previous surgical excision, corticosteroid injection, and radiation underwent reexcision of her keloid. Integra was used to cover the resultant exposed auricular perichondrium. The patient then received high–dose rate brachytherapy (1500 cGy) on postoperative days 1 and 2, followed by definitive split-thickness skin graft placement 3 weeks after her initial surgery. The patient recovered from all interventions without complication. There was no evidence of keloid formation 27 months after the interval split-thickness skin graft placement at either the auricular recipient or thigh donor sites. We report the first case of a 2-stage reconstruction of a recurrent auricular keloid (composed of keloid excision and placement of Integra in conjunction with high–dose rate brachytherapy, followed by interval split-thickness skin grafting), resulting in an acceptable cosmetic result without evidence of recurrence at long-term follow-up.

Endothelialization of Sacrificial Polymer-Derived Vascular Channels: Advancement towards the Creation of Surgically Relevant Tissue Replacements

58 CONCLUSION: Considering the importance of regenerative cells for graft survival4, standard centrifugation (at 3,000rpm/1286g during 3 minutes) although aggressive on adipocytes, cleared the fat of blood remnants5 (which was insufficient in decanted samples) and showed the highest concentration of MSCs in the pellet that could be extracted and added to fat or other substances to increase survival. The washing process was less aggressive on adipocytes and maintained a great quantity of MSCs. In other terms, washing may turn out to be the best processing technique used individually, for fat graft take as it maintains the integrity, viability of the most important components of aspirated adipose tissue.

164A: OPTIMIZING NEOVASCULARIZATION OF TISSUE REGENERATION TEMPLATES BY RATIONAL DESIGN AND MICROFABRICATION

Objective: Tissue engineering has long sought to design constructs that rapidly achieve functionality upon implantation. Current techniques, however, cannot produce pre-fabricated tissues with an intact microvascular network that is connected to macrovascular inflow and outflow vessels. Therefore, we assessed the feasibility of decellularizing tissue with an intact vascular pedicle that contains a dominant artery and vein.

7: SOLVING THE QUESTION OF PROTECTION: HYDROGEN SULFIDE CONFERS PROTECTION FROM IRI VIA ACTIVATION OF THE JAK-STAT PATHWAY

Introduction: Although there is an increasing body of evidence that demonstrates that hydrogen sulfide (HS) provides significant protection against Ischemia Reperfusion Injury (IRI), the mechanism by which this protection is conferred remains poorly understood. The JAK-STAT signaling pathway is known to regulate multiple cell processes including proliferation, differentiation and apoptosis via modulation of nuclear gene expression. Previous work has shown that this pathway is activated by mechanical preconditioning, which provides protection against IRI. We hypothesize this critical cell survival pathway would be similarly activated by treatment with HS in the setting of IR.

Therapeutic Delivery of Hydrogen Sulfide to Profoundly Ischemic Muscle: Timing Is Everything

INTRODUCTION: Hydrogen sulfide (HS) is protective effect against the detrimental effects of ischemia-reperfusion injury (IRI) when delivered either before or after an ischemic event has occurred. The optimal timing of treatment, however, remains undefined. In order to better understand the potential clinical application of HS, we sought to define the therapeutic window during which delivery of HS is protective.

115B: SALVAGE OF ENTERIC TISSUE AFTER A PERIOD OF CRITICAL ISCHEMIA: DIMINUTION OF OXIDATIVE STRESS VIA TREATMENT WITH HYDROGEN SULFIDE

Background: We have previously demonstrated that hydrogen sulfide (HS) protects intestinal tissue against ischemia-reperfusion injury (IRI) when delivered prior to the ischemic event. While an ischemic interval in free tissue transfer can be anticipated, an unexpected ischemic event in the post-operative period can be a source of additional IRIinduced morbidity. We investigated whether HS attenuates the degree of IRI when delivered after an ischemic interval.