Controlled Release of a Therapeutic Peptide in Sprayable Surgical Sealant for Prevention of Postoperative Abdominal Adhesions

Formation of asymmetric, rigid scar tissue known as surgical adhesions is caused by traumatic disruption of mesothelial-lined surfaces in surgery. A widely adopted prophylactic barrier material (Seprafilm) for the treatment of intra-abdominal adhesions is applied operatively as a pre-dried hydrogel sheet but has reduced translational efficacy due its brittle mechanical properties. Topically administered peritoneal dialysate (Icodextrin) and anti-inflammatory drugs have failed to prevent adhesions due to an uncontrolled release profile. Hence, inclusion of a targeted therapeutic into a solid barrier host matrix with improved mechanical properties could provide dual utility in adhesion prevention and as a surgical sealant. Spray deposition of poly(lactide-co-caprolactone) (PLCL) polymer fibers through solution blow spinning has yielded a tissue-adherent barrier material with previously reported adhesion prevention efficacy due to a surface erosion mechanism that inhibits deposition of inflamed tissue. However, such an approach uniquely presents an avenue for controlled therapeutic release through mechanisms of diffusion and degradation. Such a rate is kinetically tuned via facile blending of "high" molecular weight (HMW) and "low" molecular weight (LMW) PLCL with slow and fast biodegradation rates, respectively. Here, we explore viscoelastic blends of HMW PLCL (70% w/v) and LMW PLCL (30% w/v) as a host matrix for anti-inflammatory drug delivery. In this work, COG133, an apolipoprotein E (ApoE) mimetic peptide with potent anti-inflammatory properties was selected and tested. In vitro studies with PLCL blends presented low (∼30%) and high (∼80%) percent release profiles over a 14-day period based on the nominal molecular weight of the HMW PLCL component. Two independent mouse models of cecal ligation and cecal anastomosis significantly reduced adhesion severity versus Seprafilm, COG133 liquid suspension, and no treatment control. The synergy of physical and chemical methods in a barrier material with proven preclinical studies highlights the value of COG133-loaded PLCL fiber mats in effectively dampening the formation of severe abdominal adhesions.

Unsupervised and quantitative intestinal ischemia detection using conditional adversarial network in multimodal optical imaging

Purpose

Intraoperative evaluation of bowel perfusion is currently dependent upon subjective assessment. Thus, quantitative and objective methods of bowel viability in intestinal anastomosis are scarce. To address this clinical need, a conditional adversarial network is used to analyze the data from laser speckle contrast imaging (LSCI) paired with a visible-light camera to identify abnormal tissue perfusion regions.

Approach

Our vision platform was based on a dual-modality bench-top imaging system with red-green-blue (RGB) and dye-free LSCI channels. Swine model studies were conducted to collect data on bowel mesenteric vascular structures with normal/abnormal microvascular perfusion to construct the control or experimental group. Subsequently, a deep-learning model based on a conditional generative adversarial network (cGAN) was utilized to perform dual-modality image alignment and learn the distribution of normal datasets for training. Thereafter, abnormal datasets were fed into the predictive model for testing. Ischemic bowel regions could be detected by monitoring the erroneous reconstruction from the latent space. The main advantage is that it is unsupervised and does not require subjective manual annotations. Compared with the conventional qualitative LSCI technique, it provides well-defined segmentation results for different levels of ischemia.

Results

We demonstrated that our model could accurately segment the ischemic intestine images, with a Dice coefficient and accuracy of 90.77% and 93.06%, respectively, in 2560 RGB/LSCI image pairs. The ground truth was labeled by multiple and independent estimations, combining the surgeons' annotations with fastest gradient descent in suspicious areas of vascular images. The total processing time was 0.05 s for an image size of 256 × 256 .

Conclusions

The proposed cGAN can provide pixel-wise and dye-free quantitative analysis of intestinal perfusion, which is an ideal supplement to the traditional LSCI technique. It has potential to help surgeons increase the accuracy of intraoperative diagnosis and improve clinical outcomes of mesenteric ischemia and other gastrointestinal surgeries.

Sprayable tissue adhesive with biodegradation tuned for prevention of postoperative abdominal adhesions

Adhesions are dense, fibrous bridges that adjoin tissue surfaces due to uncontrolled inflammation following postoperative mesothelial injury. A widely used adhesion barrier material in Seprafilm often fails to prevent transverse scar tissue deposition because of its poor mechanical properties, rapid degradation profile, and difficulty in precise application. Solution blow spinning (SBS), a polymer fiber deposition technique, allows for the placement of in situ tissue-conforming and tissue-adherent scaffolds with exceptional mechanical properties. While biodegradable polymers such as poly(lactic-co-glycolic acid) (PLGA) have desirable strength, they exhibit bulk biodegradation rates and inflammatory profiles that limit their use as adhesion barriers and result in poor tissue adhesion. Here, viscoelastic poly(lactide-co-caprolactone) (PLCL) is used for its pertinent biodegradation mechanism. Because it degrades via surface erosion, spray deposited PLCL fibers can dissolve new connections formed by inflamed tissue, allowing them to function as an effective, durable, and easy-to-apply adhesion barrier. Degradation kinetics are tuned to match adhesion formation through the design of PLCL blends comprised of highly adhesive "low"-molecular weight (LMW) constituents in a mechanically robust "high"-molecular weight (HMW) matrix. In vitro studies demonstrate that blending LMW PLCL (30% w/v) with HMW PLCL (70% w/v) yields an anti-fibrotic yet tissue-adhesive polymer sealant with a 14-day erosion rate countering adhesion formation. PLCL blends additionally exhibit improved wet tissue adhesion strength (~10 kPa) over a 14-day period versus previously explored biodegradable polymer compositions, such as PLGA. In a mouse cecal ligation model, select PLCL blends significantly reduce abdominal adhesions severity versus no treatment and Seprafilm-treated controls.

Biodegradable, Tissue Adhesive Polyester Blends for Safe, Complete Wound Healing

Pressure-sensitive adhesives typically used for bandages are nonbiodegradable, inhibiting healing, and may cause an allergic reaction. Here, we investigated the effect of biodegradable copolymers with promising thermomechanical properties on wound healing for their eventual use as biodegradable, biocompatible adhesives. Blends of low molecular weight (LMW) and high molecular weight (HMW) poly(lactide-co-caprolactone) (PLCL) are investigated as tissue adhesives in comparison to a clinical control. Wounds treated with PLCL blend adhesives heal completely with similar vascularization, scarring, and inflammation indicators, yet require fewer dressing changes due to integration of the PLCL adhesive into the wound. A blend of LMW and HMW PLCL produces an adhesive material with significantly higher adhesive strength than either neat polymer. Wound adhesion is comparable to a polyurethane bandage, utilizing conventional nonbiodegradable adhesives designed for extremely strong adhesion.

Mediated Electrochemical Probing: A Systems-Level Tool for Redox Biology

Biology uses well-known redox mechanisms for energy harvesting (e.g., respiration), biosynthesis, and immune defense (e.g., oxidative burst), and now we know biology uses redox for systems-level communication. Currently, we have limited abilities to "eavesdrop" on this redox modality, which can be contrasted with our abilities to observe and actuate biology through its more familiar ionic electrical modality. In this Perspective, we argue that the coupling of electrochemistry with diffusible mediators (electron shuttles) provides a unique opportunity to access the redox communication modality through its electrical features. We highlight previous studies showing that mediated electrochemical probing (MEP) can "communicate" with biology to acquire information and even to actuate specific biological responses (i.e., targeted gene expression). We suggest that MEP may reveal an extent of redox-based communication that has remained underappreciated in nature and that MEP could provide new technological approaches for redox biology, bioelectronics, clinical care, and environmental sciences.

Improved Nerve Visualization in Head and Neck Surgery Using Mueller Polarimetric Imaging: Preclinical Feasibility Study in a Swine Model

BACKGROUND AND OBJECTIVES

Meticulous dissection and identification of nerves during head and neck surgery are crucial for preventing nerve damage. At present, nerve identification relies heavily on the surgeon's knowledge of anatomy, optionally combined with intraoperative neuromonitoring. Recently, optical techniques such as Mueller polarimetric imaging (MPI) have shown potential to improve nerve identification.

STUDY DESIGN/MATERIALS AND METHODS

With institutional approval, seven 25-35 kg Yorkshire pigs underwent cervical incision in the central neck. Intraoperative images were obtained using our in-house MPI system. Birefringence maps from the MPI system were processed to quantify the values between 0 and 255 from different tissue types; an active contour model was applied to further improve nerve visualization on the corresponding color images.

RESULTS

Among the seven pigs, the vagus nerves and recurrent laryngeal nerves were successfully differentiated with a mean intensity of 130.954 ± 20.611, which was significantly different (P < 0.05) from those of arteries (78.512 ± 27.78) and other surrounding tissues (82.583 ± 35.547). There were no imaging-related complications during the procedure. © 2021 Wiley Periodicals LLC.

CONCLUSIONS

MPI is a potentially complementary intraoperative tool for nerve identification in adjacent tissues.

Tracheal Agenesis: Vertical Division of the Native Esophagus - A Novel Surgical Approach and Review of the Literature

INTRODUCTION

Tracheal agenesis (TA) is rare and usually fatal. Few survivors with concomitant tracheoesophageal fistulae (TEF) who underwent ligation of the distal esophagus with creation of a spit-fistula and neo-trachea from the proximal esophagus exist. We report a novel surgical technique whereby the esophagus is divided longitudinally to preserve a functional alimentation tract and a parallel neo-trachea. We review the literature of reported cases, including survivors beyond 12 months.

METHODS

Case report and literature review.

RESULTS

A female infant with prenatal polyhydramnios was born at 35 weeks gestation with immediate respiratory distress and absent cry. Oxygenation was maintained with a laryngeal mask airway. Despite a normal appearing larynx, she could not be intubated and emergent neck exploration disclosed no cervical trachea. The patient was placed on extra corporeal membranous oxygenation (ECMO), and later diagnosed with TA, Floyd Type I. Parental desire for reconstruction but refusal of a spit-fistula necessitated a novel procedure. The esophagus was divided longitudinally via a microstapler to preserve the original alimentary tract and create a parallel neo-trachea originating from the TEF and terminating as a cervical stoma. The healing process was complicated but the baby was ultimately discharged to home where she developed normally neurologically until succumbing one night to accidental decannulation at 16 months of age.

CONCLUSION

We describe a novel surgical approach to manage TA. This includes avoiding creation of a spit fistula and preserving the native esophagus. We then survey the literature, reporting the survivorship duration and operative management of 174 reported cases of TA.

Pressure-Sensitive Tissue Adhesion and Biodegradation of Viscoelastic Polymer Blends

Viscoelastic blends of biodegradable polyesters with low and high molecular weight distributions have remarkably strong adhesion (significantly greater than 1 N/cm2) to soft, wet tissue. Those that transition from viscous flow to elastic, solidlike behavior at approximately 1 Hz demonstrate pressure-sensitivity yet also have sufficient elasticity for durable bonding to soft, wet tissue. The pressure-sensitive tissue adhesive (PSTA) blends produce increasingly stronger pull-apart adhesion in response to compressive pressure application, from 10 to 300 s. By incorporating a stiffer high molecular weight component, the PSTA exhibits dramatically improved burst pressure (greater than 100 kPa) when used as a tissue sealant. The PSTA's biodegradation mechanism can be switched from erosion (occurring primarily over the first 10 days) to bulk chemical degradation (and minimal erosion) depending on the chemistry of the high molecular weight component. Interestingly, fibrosis toward the PSTA is reduced when fast-occurring erosion is the dominant biodegradation mechanism.

Sprayable and biodegradable, intrinsically adhesive wound dressing with antimicrobial properties

Conventional wound dressings are difficult to apply to large total body surface area (TBSA) wounds, as they typically are prefabricated, require a layer of adhesive coating for fixation, and need frequent replacement for entrapped exudate. Large TBSA wounds as well as orthopedic trauma and low-resource surgery also have a high risk of infection. In this report, a sprayable and intrinsically adhesive wound dressing loaded with antimicrobial silver is investigated that provides personalized fabrication with minimal patient contact. The dressing is composed of adhesive and biodegradable poly(lactic-co-glycolic acid) and poly(ethylene glycol) (PLGA/PEG) blend fibers with or without silver salt (AgNO3). in vitro studies demonstrate that the PLGA/PEG/Ag dressing has antimicrobial properties and low cytotoxicity, with antimicrobial silver controllably released over 7-14 days. In a porcine partial-thickness wound model, the wounds treated with both antimicrobial and nonantimicrobial PLGA/PEG dressings heal at rates similar to those of the clinical, thin film polyurethane wound dressing, with similar scarring. However, PLGA/PEG adds a number of features beneficial for wound healing: greater exudate absorption, integration into the wound, a 25% reduction in dressing changes, and tissue regeneration with greater vascularization. There is also modest improvement in epidermis thickness compared to the control wound dressing.

Congenital paraesophageal hernia: Contemporary results and outcomes of laparoscopic approach to repair in symptomatic infants and children

BACKGROUND

Congenital paraesophageal hernia (CPEH) is a rare diaphragmatic anomaly for which repair has primarily been described by laparotomy, although, more recent case series describe laparoscopic repair. In reports with over five patients, the predominant approach has been with laparotomy. The purpose of our study was to review our recent institutional experience and results with exclusively laparoscopic repair of CPEH in infants and children.

METHODS

An IRB approved retrospective review of all patients with CPEH who underwent laparoscopic treatment at a tertiary children's hospital from 2010 to 2017 was performed. We included only those patients from our own institution with primary CPEH, or CPEH with prior repair (s) at other centers, with recurrence presenting for operation. Data including demographics, diagnostic studies, operative details, complications, outcomes, and follow up were analyzed. Age at diagnosis was 1 day to 25 years of age (mean 2.5 years).

RESULTS

A total 28 patients underwent 30 operations to treat CPEH. All operations were completed laparoscopically with no conversions to open. There were 6 Type II, 16 Type III, and 6 Type IV CPEH patients. Seventeen patients were less than one year of age (61%). Weight at time of repair was 10.3 kg (1.2-44 kg). Twelve patients were less than 5 kg (43%), eight patients (28.5%) were less than 10 kg, and 8 were more than 10 kg (28.5%). Operative time averaged 125 min (range 61-247 min). Three patients underwent initial CPEH repair (s) (open: 2 and laparoscopic: 1) at other institutions before laparoscopic revision was performed at our hospital (11%). Crural repair was performed in all patients, fundoplication in 26 (93%) and concomitant gastrostomy was performed in 14 patients (50%). Complications included two patients with recurrent hiatal hernias, which were redone laparoscopically (2/28 or 7% recurrence) and 1 capnothorax requiring pigtail drainage postoperatively. There were no deaths, no requirement for esophageal dilations, or esophageal lengthening. One patient required laparoscopic gastrostomy six weeks post initial repair for failure to thrive. Follow-up ranged from 4 months to 8 years (average 36 months).

CONCLUSION

Congenital paraesophageal hernia in infants and children is uncommon. Based on our experience, the laparoscopic approach to repair is feasible, even for neonates, with excellent results, acceptably low recurrence rate, and may even be considered for revisional operations.

STUDY TYPE

Clinical research paper.

LEVEL OF EVIDENCE

Type IV.

Autologous intestinal reconstruction: a single institution study of the serial transverse enteroplasty (STEP) and the longitudinal intestinal lengthening and tailoring (LILT)

PURPOSE

To review the effectiveness of the longitudinal intestinal lengthening and tailoring (LILT) and serial transverse enteroplasty (STEP) operations in a cohort of patients with short bowel syndrome (SBS).

METHODS

We conducted a retrospective analysis of children with SBS treated at our institution from 2004 until 2014. Children aged 0 days to 18 years with SBS who underwent autologous intestinal reconstruction were included in the study.

RESULTS

Twenty-two SBS patients underwent 31 different lengthening procedures (LP). Seventeen patients underwent their primary lengthening procedures at our institution: 9 (53%) patients underwent a LILT, 7 (41%) underwent a STEP and 1 (6%) had a simultaneous LILT and STEP procedure. 12/22 patients had a second STEP, two had a third STEP and one patient had an intestinal transplantation after the LP. Median intestinal length at the time of surgery was 25 cm (range 12-90 cm). There was no difference in gain of intestinal length after LILT vs. STEP (p = 0.74). Length of stay and initiation of feeds were similar. Serum albumin increased after autologous bowel lengthening (p < 0.001). 50% were weaned off parenteral nutrition (PN) (5/9 of the LILT, 1/7 of the STEP, 1/1 of the combined LILT/STEP). There were no surgical complications or deaths.

CONCLUSION

In patients with SBS, LILT and STEP procedures are effective for autologous intestinal reconstruction and enable intestinal rehabilitation.

Improving the adhesion, flexibility, and hemostatic efficacy of a sprayable polymer blend surgical sealant by incorporating silica particles

Commercially available surgical sealants for internal use either lack sufficient adhesion or produce cytotoxicity. This work describes a surgical sealant based on a polymer blend of poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) that increases wet tissue adherence by incorporation of nano-to-microscale silica particles, without significantly affecting cell viability, biodegradation rate, or local inflammation. In functional studies, PLGA/PEG/silica composite sealants produce intestinal burst pressures that are comparable to cyanoacrylate glue (160 mmHg), ∼2 times greater than the non-composite sealant (59 mmHg), and ∼3 times greater than fibrin glue (49 mmHg). The addition of silica to PLGA/PEG is compatible with a sprayable in situ deposition method called solution blow spinning and decreases coagulation time in vitro and in vivo. These improvements are biocompatible and cause minimal additional inflammation, demonstrating the potential of a simple composite design to increase adhesion to wet tissue through physical, noncovalent mechanisms and enable use in procedures requiring simultaneous occlusion and hemostasis. STATEMENT OF SIGNIFICANCE: Incorporating silica particles increases the tissue adhesion of a polymer blend surgical sealant. The particles enable interfacial physical bonding with tissue and enhance the flexibility of the bulk of the sealant, without significantly affecting cytotoxicity, inflammation, or biodegradation. These studies also demonstrate how silica particles decrease blood coagulation time. This surgical sealant improves upon conventional devices because it can be easily deposited with accuracy directly onto the surgical site as a solid polymer fiber mat. The deposition method, solution blow spinning, allows for high loading in the composite fibers, which are sprayed from a polymer blend solution containing suspended silica particles. These findings could easily be translated to other implantable or wearable devices due to the versatility of silica particles.

Closure methods in gastroschisis

The expected outcome of gastroschisis has evolved from an almost certain death of the child prior to the use of parenteral nutrition to almost certain survival. The primary goal of the surgical intervention is return of eviscerated contents into the abdominal cavity. The optimal surgical technique is dependent on the status of the intestine and the accommodation of abdominal domain. In this review, the various surgical techniques for management are discussed as they have evolved. Ironically, a minimalist surgical intervention originally practiced due to the poor expected outcome is now being adopted as a minimalist surgical approach for abdominal wall closure associated with an expected excellent outcome.

Changes in Autonomic Tone in Premature Infants Developing Necrotizing Enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is a complication of prematurity with a high mortality rate. Currently, there are no reliable biomarkers capable of identifying infants at risk for developing NEC. We sought to determine the autonomic nervous system antecedents of NEC in premature infants, using heart rate variability (HRV).

MATERIALS AND METHODS

HRV was quantified by retrieving archived electrocardiogram (EKG) data from 30 premature infants from 4 days prior, through 4 days after, the clinical NEC diagnosis. HRV metrics were compared with those on the diagnosis day using the receiver operating characteristic (ROC) analysis.

RESULTS

HRV metrics showed a depression of autonomic tone that preceded the clinical NEC diagnosis by 2 days, and which recovered to baseline by 2 days after diagnosis (area under the curve [AUC] < 0.7). The pattern of HRV change was significantly associated with the clinical severity of NEC (stage II vs. stage III).

CONCLUSION

Our studies suggest that readily accessible metrics of autonomic depression might expedite the diagnosis of NEC and its severity in a clinically meaningful manner. Clearly, these studies need to be extended prospectively to determine the diagnostic utility of this approach.

Molecular and functional analysis of anchorage independent, treatment-evasive neuroblastoma tumorspheres with enhanced malignant properties: A possible explanation for radio-therapy resistance

Despite significant advances in cancer treatment and management, more than 60% of patients with neuroblastoma present with very poor prognosis in the form of metastatic and aggressive disease. Solid tumors including neuroblastoma are thought to be heterogeneous with a sub-population of stem-like cells that are treatment-evasive with highly malignant characteristics. We previously identified a phenomenon of reversible adaptive plasticity (RAP) between anchorage dependent (AD) cells and anchorage independent (AI) tumorspheres in neuroblastoma cell cultures. To expand our molecular characterization of the AI tumorspheres, we sought to define the comprehensive proteomic profile of murine AD and AI neuroblastoma cells. The proteomic profiles of the two phenotypic cell populations were compared to each other to determine the differential protein expression and molecular pathways of interest. We report exclusive or significant up-regulation of tumorigenic pathways expressed by the AI tumorspheres compared to the AD cancer cells. These pathways govern metastatic potential, enhanced malignancy and epithelial to mesenchymal transition. Furthermore, radio-therapy induced significant up-regulation of specific tumorigenic and proliferative proteins, namely survivin, CDC2 and the enzyme Poly [ADP-ribose] polymerase 1. Bio-functional characteristics of the AI tumorspheres were resistant to sutent inhibition of receptor tyrosine kinases (RTKs) as well as to 2.5 Gy radio-therapy as assessed by cell survival, proliferation, apoptosis and migration. Interestingly, PDGF-BB stimulation of the PDGFRβ led to transactivation of EGFR and VEGFR in AI tumorspheres more potently than in AD cells. Sutent inhibition of PDGFRβ abrogated this transactivation in both cell types. In addition, 48 h sutent treatment significantly down-regulated the protein expression of PDGFRβ, MYCN, SOX2 and Survivin in the AI tumorspheres and inhibited tumorsphere self-renewal. Radio-sensitivity in AI tumorspheres was enhanced when sutent treatment was combined with survivin knock-down. We conclude that AI tumorspheres have a differential protein expression compared to AD cancer cells that contribute to their malignant phenotype and radio-resistance. Specific targeting of both cellular phenotypes is needed to improve outcomes in neuroblastoma patients.

PD-L1 checkpoint inhibition and anti-CTLA-4 whole tumor cell vaccination counter adaptive immune resistance: A mouse neuroblastoma model that mimics human disease

BACKGROUND

Adaptive immune resistance induces an immunosuppressive tumor environment that enables immune evasion. This phenomenon results in tumor escape with progression and metastasis. Programmed cell death-ligand 1 (PD-L1) expressed on tumors is thought to inhibit tumor-infiltrating lymphocytes (TILs) through programmed cell death 1 (PD1), enabling adaptive immune resistance. This study investigates the role of PD-L1 in both mouse and human neuroblastoma immunity. The consequence of PD-L1 inhibition is characterized in the context of an established whole tumor cell vaccine.

METHODS AND FINDINGS

A mouse model of neuroblastoma was investigated using an Id2 knockdown whole cell vaccine in combination with checkpoint inhibition. We show that immunogenic mouse neuroblastoma acquires adaptive immune resistance by up-regulating PD-L1 expression, whereas PD-L1 is of lesser consequence in nonimmunogenic neuroblastoma tumors. Combining PD-L1 checkpoint inhibition with whole tumor cell/anti-CTLA-4 vaccination enhanced tumor cell killing, cured mice with established tumors, and induced long-term immune memory (6 months). From an evaluation of patient neuroblastoma tumors, we found that the inflammatory environment of the mouse neuroblastoma mimicked human disease in which PD-L1 expression was associated directly with TILs and lower-risk tumors. High-risk patient tumors were lacking both TILs and PD-L1 expression. Although a correlation in immunity seems to exist between the mouse model and human findings, the mouse tumor model is induced and not spontaneously occurring, and furthermore, the number of both mouse and human correlates is limited.

CONCLUSIONS

This study demonstrates the role PD-L1 plays in neuroblastoma's resistance to immunity and defines the nonredundant effect of combination checkpoint inhibition with vaccine therapy in a mouse model. High-risk, nonimmunogenic human tumors display both diminished PD-L1 expression and adaptive immune resistance. Paradoxically, high-risk tumors may be more responsive to effective vaccine therapy because of their apparent lack of adaptive immune resistance.

Solution blow spun polymer: A novel preclinical surgical sealant for bowel anastomoses

BACKGROUND

Solution blow spinning is a technique for depositing polymer fibers with promising potential use as a surgical sealant. This study assessed the feasibility and efficacy of solution blow spun polymer (BSP) for sealing bowel perforations in a mouse model of partial cecal transection. We then evaluated its use for reinforcing a surgical anastomosis in a preclinical piglet model.

METHODS

Three commercially available surgical sealants (fibrin glue, polyethylene glycol (PEG) hydrogel, and cyanoacrylate) were compared to BSP in the ability to seal partially transected cecum in mice. For anastomosis feasibility testing in a piglet model, piglets were subjected to small bowel transection with sutured anastomosis reinforced with BSP application. Outcome measures included anastomotic burst pressure, anastomotic leak rate, 14-day survival, and complication rate.

RESULTS

For the mouse model, the survival rates for the sealants were 30% for fibrin glue, 20% for PEG hydrogel, 78% for cyanoacrylate, and 67% for BSP. Three of 9 mice died after BSP administration because of perforation leak, failure to thrive with partial obstruction at the perforation site, and unknown causes. All other mice died of perforation leak. The mean burst pressure at 24h was significantly higher for BSP (81mm Hg) when compared to fibrin glue (6mm Hg, p=0.047) or PEG hydrogel (10mm Hg, p=0.047), and comparable to cyanoacrylate (64mm Hg, p=0.91). For piglets, 4 of 4 animals survived at 14days. Mean burst pressures at time of surgery were 37±5mm Hg for BSP and 11±9mm Hg for suture-only controls (p=0.09).

CONCLUSIONS

Solution blow spinning may be an effective technique as an adjunct for sealing of gastrointestinal anastomosis. Further preclinical testing is warranted to better understand BSP properties and alternative surgical applications.

Prussian blue nanoparticle-based photothermal therapy combined with checkpoint inhibition for photothermal immunotherapy of neuroblastoma

We describe "photothermal immunotherapy," which combines Prussian blue nanoparticle (PBNP)-based photothermal therapy (PTT) with anti-CTLA-4 checkpoint inhibition for treating neuroblastoma, a common, hard-to-treat pediatric cancer. PBNPs exhibit pH-dependent stability, which makes them suitable for intratumorally-administered PTT. PBNP-based PTT is able to lower tumor burden and prime an immune response, specifically an increased infiltration of lymphocytes and T cells to the tumor area, which is complemented by the antitumor effects of anti-CTLA-4 immunotherapy, providing a more durable treatment against neuroblastoma in an animal model. We observe 55.5% survival in photothermal immunotherapy-treated mice at 100days compared to 12.5%, 0%, 0%, and 0% survival in mice receiving: anti-CTLA-4 alone, PBNPs alone, PTT alone, and no treatment, respectively. Additionally, long-term surviving, photothermal immunotherapy-treated mice exhibit protection against neuroblastoma rechallenge, suggesting the development of immunity against these tumors. Our findings suggest the potential of photothermal immunotherapy in improving treatments for neuroblastoma.

A Review of the Fundamental Principles and Applications of Solution Blow Spinning

Solution blow spinning (SBS) is a technique that can be used to deposit fibers in situ at low cost for a variety of applications, which include biomedical materials and flexible electronics. This review is intended to provide an overview of the basic principles and applications of SBS. We first describe a method for creating a spinnable polymer solution and stable polymer solution jet by manipulating parameters such as polymer concentration and gas pressure. This method is based on fundamental insights, theoretical models, and empirical studies. We then discuss the unique bundled morphology and mechanical properties of fiber mats produced by SBS, and how they compare with electrospun fiber mats. Applications of SBS in biomedical engineering are highlighted, showing enhanced cell infiltration and proliferation versus electrospun fiber scaffolds and in situ deposition of biodegradable polymers. We also discuss the impact of SBS in applications involving textiles and electronics, including ceramic fibers and conductive composite materials. Strategies for future research are presented that take advantage of direct and rapid polymer deposition via cost-effective methods.

Surgical management of esophageal achalasia: Evolution of an institutional approach to minimally invasive repair

BACKGROUND

Surgical management of esophageal achalasia (EA) in children has transitioned over the past 2 decades to predominantly involve laparoscopic Heller myotomy (LHM) or minimally invasive surgery (MIS). More recently, peroral endoscopic myotomy (POEM) has been utilized to treat achalasia in children. Since the overall experience with surgical management of EA is contingent upon disease incidence and surgeon experience, the aim of this study is to report a single institutional contemporary experience for outcomes of surgical treatment of EA by LHM and POEM, with regards to other comparable series in children.

METHODS

An IRB approved retrospective review of all patients with EA who underwent treatment by a surgical approach at a tertiary US children's hospital from 2006 to 2015. Data including demographics, operative approach, Eckardt scores pre- and postoperatively, complications, outcomes, and follow-up were analyzed.

RESULTS

A total of 33 patients underwent 35 operative procedures to treat achalasia. Of these operations; 25 patients underwent laparoscopic Heller myotomy (LHM) with Dor fundoplication; 4 patients underwent LHM alone; 2 patients underwent LHM with Thal fundoplication; 2 patients underwent primary POEM; 2 patients who had had LHM with Dor fundoplication underwent redo LHM with takedown of Dor fundoplication. Intraoperative complications included 2 mucosal perforations (6%), 1 aspiration, 1 pneumothorax (1 POEM patient). Follow ranged from 8months to 7years (8-84months). There were no deaths and no conversions to open operations. Five patients required intervention after surgical treatment of achalasia for recurrent dysphagia including 3 who underwent between 1 and 3 pneumatic dilations; and 2 who had redo LHM with takedown of Dor fundoplication with all patients achieving complete resolution of symptoms.

CONCLUSIONS

Esophageal achalasia in children occurs at a much lower incidence than in adults as documented by published series describing the surgical treatment in children. We believe the MIS surgical approach remains the standard of care for this condition in children and describe the surgical outcomes and complications for LHM, as well as, the introduction of the POEM technique in our center for treating achalasia. Our institutional experience described herein represents the largest in the "MIS era" with excellent results. We will refer to alterations in our practice that have included the use of flexible endoscopy in 100% of LHM cases and use of the endoscopic functional lumen imaging probe (EndoFLIP) in both LHM and POEM cases which we believe enables adequate Heller myotomy.

VBP15, a novel dissociative steroid compound, reduces NFκB-induced expression of inflammatory cytokines in vitro and symptoms of murine trinitrobenzene sulfonic acid-induced colitis

OBJECTIVE AND DESIGN

The goal of this study was to assess the capacity of VBP15, a dissociative steroidal compound, to reduce pro-inflammatory cytokine expression in vitro, to reduce symptoms of colitis in the trinitrobenzene sulfonic acid-induced murine model, and to assess the effect of VBP15 on growth stunting in juvenile mice.

MATERIALS

In vitro studies were performed in primary human intestinal epithelial cells. Colitis was induced in mice by administering trinitrobenzene sulfonic acid. Growth stunting studies were performed in wild type outbred mice.

TREATMENT

Cells were treated with VBP15 or prednisolone (10 μM) for 24 h. Mice were subjected to 3 days of VBP15 (30 mg/kg) or prednisolone (30 mg/kg) in the colitis study. In the growth stunting study, mice were subjected to VBP15 (10, 30, 45 mg/kg) or prednisolone (10 mg/kg) for 5 weeks.

METHODS

Cytokines were measured by PCR and via Luminex. Colitis symptoms were evaluated by assessing weight loss, intestinal blood, and stool consistency. Growth stunting was assessed using an electronic caliper.

RESULTS

VBP15 significantly reduced the in vitro production of CCL5 (p < 0.001) IL-6 (p < 0.001), IL-8 (p < 0.05) and reduced colitis symptoms (p < 0.05). VBP15 caused less growth stunting than prednisolone (p < 0.001) in juvenile mice.

CONCLUSION

VBP15 may reduce symptoms of IBD, while decreasing or avoiding detrimental side effects.

Biodegradable-Polymer-Blend-Based Surgical Sealant with Body-Temperature-Mediated Adhesion

The development of practical and efficient surgical sealants has the propensity to improve operational outcomes. A biodegradable polymer blend is fabricated as a nonwoven fiber mat in situ. After direct deposition onto the tissue of interest, the material transitions from a fiber mat to a film. This transition promotes polymer-substrate interfacial interactions leading to improved adhesion and surgical sealant performance.

Are Immune Modulating Single Nucleotide Polymorphisms Associated with Necrotizing Enterocolitis?

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal emergency. The purpose of this study is to determine if functional single nucleotide polymorphisms (SNPs) in immune-modulating genes pre-dispose infants to NEC. After Institutional Review Board approval and parental consent, buccal swabs were collected for DNA extraction. TaqMan allelic discrimination assays and BglII endonuclease digestion were used to genotype specific inflammatory cytokines and TRIM21. Statistical analysis was completed using logistic regression. 184 neonates were analyzed in the study. Caucasian neonates with IL-6 (rs1800795) were over 6 times more likely to have NEC (p = 0.013; OR = 6.61, 95% CI 1.48–29.39), and over 7 times more likely to have Stage III disease (p = 0.011; OR = 7.13, (95% CI 1.56–32.52). Neonates with TGFβ-1 (rs2241712) had a decreased incidence of NEC-related perforation (p = 0.044; OR = 0.28, 95% CI: 0.08–0.97) and an increased incidence of mortality (p = 0.049; OR = 2.99, 95% CI: 1.01 – 8.86). TRIM21 (rs660) was associated with NEC-related intestinal perforation (p = 0.038; OR = 4.65, 95% CI 1.09–19.78). In premature Caucasian neonates, the functional SNP IL-6 (rs1800795) is associated with both the development and increased severity of NEC. TRIM21 (rs660) and TGFβ-1 (rs2241712) were associated with NEC- related perforation in all neonates in the cohort. These findings suggest a possible genetic role in the development of NEC.

Combination of Id2 Knockdown Whole Tumor Cells and Checkpoint Blockade: A Potent Vaccine Strategy in a Mouse Neuroblastoma Model

Tumor vaccines have held much promise, but to date have demonstrated little clinical success. This lack of success is conceivably due to poor tumor antigen presentation combined with immuno-suppressive mechanisms exploited by the tumor itself. Knock down of Inhibitor of differentiation protein 2 (Id2-kd) in mouse neuroblastoma whole tumor cells rendered these cells immunogenic. Id2-kd neuroblastoma (Neuro2a) cells (Id2-kd N2a) failed to grow in most immune competent mice and these mice subsequently developed immunity against further wild-type Neuro2a tumor cell challenge. Id2-kd N2a cells grew aggressively in immune-compromised hosts, thereby establishing the immunogenicity of these cells. Therapeutic vaccination with Id2-kd N2a cells alone suppressed tumor growth even in established neuroblastoma tumors and when used in combination with immune checkpoint blockade eradicated large established tumors. Mechanistically, immune cell depletion studies demonstrated that while CD8+ T cells are critical for antitumor immunity, CD4+ T cells are also required to induce a sustained long-lasting helper effect. An increase in number of CD8+ T-cells and enhanced production of interferon gamma (IFNγ) was observed in tumor antigen stimulated splenocytes of vaccinated mice. More importantly, a massive influx of cytotoxic CD8+ T-cells infiltrated the shrinking tumor following combined immunotherapy. These findings show that down regulation of Id2 induced tumor cell immunity and in combination with checkpoint blockade produced a novel, potent, T-cell mediated tumor vaccine strategy.

Culture-independent evaluation of the appendix and rectum microbiomes in children with and without appendicitis

PURPOSE

The function of the appendix is largely unknown, but its microbiota likely contributes to function. Alterations in microbiota may contribute to appendicitis, but conventional culture studies have not yielded conclusive information. We conducted a pilot, culture-independent 16S rRNA-based microbiota study of paired appendix and rectal samples.

METHODS

We collected appendix and rectal swabs from 21 children undergoing appendectomy, six with normal appendices and fifteen with appendicitis (nine perforated). After DNA extraction, we amplified and sequenced 16S rRNA genes and analyzed sequences using CLoVR. We identified organisms differing in relative abundance using ANOVA (p<0.05) by location (appendix vs. rectum), disease (appendicitis vs. normal), and disease severity (perforated vs. non-perforated).

RESULTS

We identified 290 taxa in the study's samples. Three taxa were significantly increased in normal appendices vs. normal rectal samples: Fusibacter (p = 0.009), Selenomonas (p = 0.026), and Peptostreptococcus (p = 0.049). Five taxa were increased in abundance in normal vs. diseased appendices: Paenibacillaceae (p = 0.005), Acidobacteriaceae GP4 (p = 0.019), Pseudonocardinae (p = 0.019), Bergeyella (p = 0.019) and Rhizobium (p = 0.045). Twelve taxa were increased in the appendices of appendicitis patients vs. normal appendix: Peptostreptococcus (p = 0.0003), Bilophila (p = 0.0004), Bulleidia (p = 0.012), Fusobacterium (p = 0.018), Parvimonas (p = 0.003), Mogibacterium (p = 0.012), Aminobacterium (p = 0.019), Proteus (p = 0.028), Actinomycineae (p = 0.028), Anaerovorax (p = 0.041), Anaerofilum (p = 0.045), Porphyromonas (p = 0.010). Five taxa were increased in appendices in patients with perforated vs. nonperforated appendicitis: Bulleidia (p = 0.004), Fusibacter (p = 0.005), Prevotella (p = 0.021), Porphyromonas (p = 0.030), Dialister (p = 0.035). Three taxa were increased in rectum samples of patients with appendicitis compared to the normal patients: Bulleidia (p = 0.034), Dialister (p = 0.003), and Porphyromonas (p = 0.026).

CONCLUSION

Specific taxa are more abundant in normal appendices compared to the rectum, suggesting that a distinctive appendix microbiota exists. Taxa with altered abundance in diseased and severely diseased (perforated) samples may contribute to appendicitis pathogenesis, and may provide microbial signatures in the rectum useful for guiding both treatment and diagnosis of appendicitis.

In Situ Deposition of PLGA Nanofibers via Solution Blow Spinning

Nanofiber mats and scaffolds have been widely investigated for biomedical applications. Commonly fabricated using electrospinning, nanofibers are generated ex situ using an apparatus that requires high voltages and an electrically conductive target. We report the use of solution blow spinning to generate conformal nanofiber mats/meshes on any surface in situ, utilizing only a commercial airbrush and compressed CO₂. Solution and deposition conditions of PLGA nanofibers were optimized and mechanical properties characterized with dynamic mechanical analysis. Nanofiber mat degradation was monitored for morphologic and molecular weight changes in vitro. Biocompatibility of the direct deposition of nanofibers onto two cell lines was demonstrated in vitro and interaction with blood was qualitatively assessed with scanning electron microscopy. A pilot animal study illustrated the wide potential of this technique across multiple surgical applications, including its use as a surgical sealant, hemostatic, and buttress for tissue repair.

A mechanism linking Id2-TGFβ crosstalk to reversible adaptive plasticity in neuroblastoma

The ability of high-risk neuroblastoma to survive unfavorable growth conditions and multimodal therapy has produced an elusive childhood cancer with remarkably poor prognosis. A novel phenomenon enabling neuroblastoma to survive selection pressure is its capacity for reversible adaptive plasticity. This plasticity allows cells to transition between highly proliferative anchorage dependent (AD) and slow growing, anoikis-resistant anchorage independent (AI) phenotypes. Both phenotypes are present in established mouse and human tumors. The differential gene expression profile of the two cellular phenotypes in the mouse Neuro2a cell line delineated pathways of proliferation in AD cells or tyrosine kinase activation/ apoptosis inhibition in AI cells. A 20 fold overexpression of inhibitor of differentiation 2 (Id2) was identified in AD cells while up-regulation of genes involved in anoikis resistance like PI3K/Akt, Erk, Bcl2 and integrins was observed in AI cells. Similarly, differential expression of Id2 and other genes of interest were also observed in the AD and AI phenotypes of human neuroblastoma cell lines, SK-N-SH and IMR-32; as well as in primary human tumor specimens. Forced down-regulation of Id2 in AD cells or overexpression in AI cells induced the cells to gain characteristics of the other phenotype. Id2 binds both TGFβ and Smad2/3 and appears critical for maintaining the proliferative phenotype at least partially through negative regulation of the TGFβ/Smad pathway. Simultaneously targeting the differential molecular pathways governing reversible adaptive plasticity resulted in 50% cure of microscopic disease and delayed tumor growth in established mouse neuroblastoma tumors. We present a mechanism that accounts for reversible adaptive plasticity and a molecular basis for combined targeted therapies in neuroblastoma.

Abstract 5042: The mechanism of reversible adaptive plasticity in neuroblastoma

Neuroblastoma (NB) is a pediatric cancer originating from neural crest-derived progenitors. This disease displays considerable clinical diversity, ranging from spontaneous regression to lethal disease. Heterogeneity within cancer cell populations is common and can arise through multiple mechanisms including genetic/epigenetic changes, microenvironmental influences, resistance to anoikis or presence of cancer stem cells. We have recently described a novel form of tumor cell transformation in NB termed reversible adaptive plasticity. Two defined NB phenotypes with anchorage dependent (AD) and anchorage independent (AI) growth patterns were observed in mouse and human cell lines under distinct culture conditions. These phenotypes are capable of reversible transition and identification of specific molecular markers enabled us to observe both phenotypes in established mouse and human NB tumors. In an effort to investigate the mechanism(s) driving this reversible transition in NB, we sought to determine the gene expression profile of the AD and AI phenotypes. In so doing, we were able to elucidate the molecular patterns and pathways associated with each phenotype. Affymetrix gene array analysis of the mouse Neuro2a cells revealed remarkable differences between the two phenotypes in vitro. 1180 genes were differentially expressed and delineated pathways of proliferation in AD cells or tyrosine kinase activation/ apoptosis inhibition in AI cells. In particular, inhibitor of differentiation 2 (Id2) was found to be 20 fold higher in AD while in AI, genes involved in anoikis resistance like PI3K/Akt, Erk, Bcl2 and integrins were upregulated. We hypothesized that Id2 plays a critical role in mediating phenotypic transition of the NB cells. Down-regulation of Id2 expression in the AD phenotype of NB cells with either antisense Id2 oligonucleotide or Id2-siRNA decreased proliferation, increased cell cycle exit, induced apoptosis and resulted in over-activation of Akt and Integrin/Raf/Erk pathways. This altered phenotype was similar to the AI cells in which anoikis resistance is evident. These findings describe the signaling pathways inducing reversible adaptive plasticity in NB. Id2 appears critical for maintaining the proliferative AD phenotype while down-regulating this pathway results in up-regulation of mechanisms governing transition to the anoikis resistant AI phenotype. In a mouse model of NB, targeting both cell phenotypes with the combination of doxorubicin (AD targeting) and Sorafenib (AI targeting) resulted in significant delay in tumor growth compared to either agent alone, highlighting the importance of adaptive plasticity in NB biology.

Citation Format: Lina Chakrabarti, Bi-Dar Wang, Norman H. Lee, Anthony D. Sandler. The mechanism of reversible adaptive plasticity in neuroblastoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5042. doi:10.1158/1538-7445.AM2013-5042

Abstract 2771: Development of a non-thermal plasma model for neuroblastoma treatment

Neuroblastoma is a common extra-cranial solid tumor in children. There are several clinical categories of this disease, ranging from curable to very poor prognosis in which this cancer is treated with multi-modal therapy. We have tested a novel ablative technology, using non-thermal helium generated plasma jets, as a means to selective targeting of neuroblastoma cells. Plasma consists of partially ionized molecules, free radicals and other species. We have investigated the molecular mechanisms involved in non-thermal plasma mediated tumor cell death, as well as the differences in response between tumor and normal cells. Treatment with non-thermal plasma induced apoptosis in cancer cells, while normal cells appear to be less sensitive to the toxic effects. Levels of reactive oxygen species (ROS) such as superoxide anion and hydrogen peroxide are elevated after plasma treatment, suggesting that this may contribute to cell death. Scavengers of ROS were able to abrogate apoptosis in plasma-treated cells. Plasma therapy of tumor cells may be a novel approach to delivery of high levels of ROS, offering the ability to directly target and selectively destroy neoplastic tissue. Methods enhancing the ROS effect and/or technical delivery of the free radicals uniformly to tumor cells within a mass will be needed before this technology could be translated to ablating solid tumors in vivo.

Citation Format: Priya Srinivasan, Jason A. Snyder, Alexey Shashurin, Michael Keidar, Anthony D. Sandler. Development of a non-thermal plasma model for neuroblastoma treatment. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2771. doi:10.1158/1538-7445.AM2013-2771

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

T-cell activation is enhanced by targeting IL-10 cytokine production in toll-like receptor-stimulated macrophages

Toll-like receptor (TLR) agonists represent potentially useful cancer vaccine adjuvants in their ability to stimulate antigen-presenting cells (APCs) and subsequently amplify the cytotoxic T-cell response. The purpose of this study was to characterize APC responses to TLR activation and to determine the subsequent effect on lymphocyte activation. We exposed murine primary bone marrow-derived macrophages to increasing concentrations of agonists to TLRs 2, 3, 4, and 9. This resulted in a dose-dependent increase in production of not only tumor necrosis factor–alpha (TNF-α), a surrogate marker of the proinflammatory response, but also interleukin 10 (IL-10), a well-described inhibitory cytokine. Importantly, IL-10 secretion was not induced by low concentrations of TLR agonists that readily produced TNF-α. We subsequently stimulated lymphocytes with anti-CD3 antibody in the presence of media from macrophages activated with higher doses of TLR agonists and observed suppression of interferon gamma release. Use of both IL-10 knockout macrophages and IL-10 small-interfering RNA (siRNA) ablated this suppressive effect. Finally, IL-10 siRNA was successfully used to suppress CpG-induced IL-10 production in vivo. We conclude that TLR-mediated APC stimulation can induce a paradoxical inhibitory effect on T-cell activation mediated by IL-10.

Management of congenital chest wall deformities

Congenital chest wall deformities are considered to be anomalies in chest wall growth. These can be categorized as either rib cage overgrowth or deformities related to inadequate growth (aplasia or dysplasia). Rib cage overgrowth leads to depression of the sternum (pectus excavatum) or protuberance of the sternum (pectus carinatum) and accounts for greater than 90% of congenital chest wall deformities. The remaining deformities are a result of inadequate growth. Evolution in the management of congenital chest wall deformities has made significant progress over the past 25 years. This article will review chest wall deformities and the current management strategies of these interesting anomalies.

Increased incidence of perforated appendicitis in children with obesity

Based on their clinical impression, the authors hypothesized that children with obesity may more commonly present with perforated appendicitis. Therefore, the authors reviewed their experience from 2008 to 2010 to determine whether obesity affected the clinical presentation of appendicitis. Variables studied were height, weight, use of diagnostic imaging, and clinical findings of appendicitis at presentation. Outcomes assessed were length of stay and complication rate. The study identified 319 patients with appendicitis. Children with obesity were more likely (P = .026) to present with perforation (28/62, 45%) than nonobese patients (78/257, 30%). Neither length of stay nor complication rate was affected by the presence of obesity. The data suggest that children with obesity are more likely to present with perforated appendicitis. This finding suggests that the diagnosis of appendicitis may be more difficult in obese patients or their presentation may be delayed. Practitioners should have heightened awareness in children with obesity and symptoms of abdominal pain.

Reversible adaptive plasticity: a mechanism for neuroblastoma cell heterogeneity and chemo-resistance

We describe a novel form of tumor cell plasticity characterized by reversible adaptive plasticity in murine and human neuroblastoma. Two cellular phenotypes were defined by their ability to exhibit adhered, anchorage dependent (AD) or sphere forming, anchorage independent (AI) growth. The tumor cells could transition back and forth between the two phenotypes and the transition was dependent on the culture conditions. Both cell phenotypes exhibited stem-like features such as expression of nestin, self-renewal capacity, and mesenchymal differentiation potential. The AI tumorspheres were found to be more resistant to chemotherapy and proliferated slower in vitro compared to the AD cells. Identification of specific molecular markers like MAP2, β-catenin, and PDGFRβ enabled us to characterize and observe both phenotypes in established mouse tumors. Irrespective of the phenotype originally implanted in mice, tumors grown in vivo show phenotypic heterogeneity in molecular marker signatures and are indistinguishable in growth or histologic appearance. Similar molecular marker heterogeneity was demonstrated in primary human tumor specimens. Chemotherapy or growth factor receptor inhibition slowed tumor growth in mice and promoted initial loss of AD or AI heterogeneity, respectively. Simultaneous targeting of both phenotypes led to further tumor growth delay with emergence of new unique phenotypes. Our results demonstrate that neuroblastoma cells are plastic, dynamic, and may optimize their ability to survive by changing their phenotype. Phenotypic switching appears to be an adaptive mechanism to unfavorable selection pressure and could explain the phenotypic and functional heterogeneity of neuroblastoma.

Immunostimulatory sutures that treat local disease recurrence following primary tumor resection

Neuroblastoma is a common childhood cancer that often results in progressive minimal residual disease after primary tumor resection. Cytosine-phosphorothioate-guanine oligonucleotides (CpG ODN) have been reported to induce potent anti-tumor immune responses. In this communication, we report on the development of a CpG ODN-loaded suture that can close up the wound following tumor excision and provide sustained localized delivery of CpG ODN to treat local disease recurrence. The suture was prepared by melt extruding a mixture of polylactic acid-co-glycolic acid (PLGA 75:25 0.47 dL g⁻¹) pellets and CpG ODN 1826. Scanning electron microscopy images showed that the sutures were free of defects and cracks. UV spectrophotometry measurements at 260 nm showed that sutures provide sustained release of CpG ODN over 35 days. Syngeneic female A/J mice were inoculated subcutaneously with 1 × 10⁶ Neuro-2a murine neuroblastoma wild-type cells and tumors were grown between 5 to 10 mm before the tumors were excised. Wounds from the tumor resection were closed using CpG ODN-loaded sutures and/or polyglycolic acid Vicryl suture. Suppression of neuroblastoma recurrence and mouse survival were significantly higher in mice where wounds were closed using the CpG ODN-loaded sutures relative to all other groups.

Effective adoptive therapy of tap-deficient lymphoma using diverse high avidity alloreactive T cells

High avidity for antigen and diversity of T cell receptor (TCR) repertoire are essential for effective immunity against cancer. We have previously created a transgenic mouse strain with increased TCR avidity in a diverse T cell population. In this report, we show that strong alloreactive responses of transgenic T cells against targets with low MHC class I expression can be used for effective adoptive transfer of tumor immunity in vivo. Alloreactive transgenic T cells could be an effective therapeutic approach counteracting tumor evasion of the immune system.

Immune stimulatory antigen loaded particles combined with depletion of regulatory T-cells induce potent tumor specific immunity in a mouse model of melanoma

Anti-tumor vaccines capable of activating both CD4 and CD8 T cells are preferred for long lasting T cell responses. Induction of a tumor-specific T-cell response can be induced by tumor vaccines that target innate immunity. The ensuing T-cell response depends on efficient antigen presentation from phagocytosed cargo in the antigen presenting cell and is augmented by the presence of Toll-like receptor (TLR) ligands within the cargo. Biodegradable polymers are useful for vaccine delivery in that they are phagocytosed by antigen presenting cells (APCs) and could potentially be loaded with both the antigen and immune stimulatory TLR agents. This study was undertaken to evaluate the effect of poly lactic-co-glycolic acid (PLGA) polymer particles loaded with antigenic tumor lysate and immune stimulatory CpG oligonucleotides on induction of tumor specific immunity in a mouse model of melanoma. We found that after delivery, these immune stimulatory antigen loaded particles (ISAPs) efficiently activated APCs and were incorporated into lysosomal compartments of macrophages and dendritic cells. ISAP vaccination resulted in remarkable T cell proliferation, but only modestly suppressed tumor growth of established melanoma. Due to this discordant effect on tumor immunity we evaluated the role of regulatory T cells (Treg) and found that ISAP vaccination or tumor growth alone induced prolific expansion of tumor specific Treg. When the Treg compartment was suppressed with anti-CD25 antibody, ISAP vaccination induced complete antigen-specific immunity in a prophylactic model. ISAP vaccination is a novel tumor vaccine strategy that is designed to co-load the antigen with a TLR agonist enabling efficient Ag presentation. Targeting of T-reg expansion during vaccination may be necessary for inducing effective tumor-specific immunity.

Robotic resection of mediastinal masses in children

PURPOSE

Robotic surgery may be particularly well suited for solid chest masses. In this paper, we present our initial experience by using robotic surgery to resect mediastinal masses in children.

METHODS

Five pediatric patients with an average age of 9.8 years (range, 2-17) and an average weight of 41.5 kg (range, 13.9-70.5) underwent a robotic resection of a mediastinal chest mass using the da Vinci Surgical Robot (Intuitive Surgical, Sunnyvale, CA).

RESULTS

Operative time ranged from 44 to 156 minutes, with an average of 113 minutes. The pathology varied considerably and included a ganglioneuroma, ganglioneuroblastoma, teratoma, germ cell tumor, and a large inflammatory mass of unclear etiology. No complications or conversions occurred. Average length of hospitalization was 1.4 days. Follow-up averaged 2 years, with no evidence of recurrence in any patient.

CONCLUSIONS

Robotic surgery is safe and effective for resecting solid mediastinal chest masses. The articulating instruments are particularly helpful for dissecting around a solid mass within the rigid thoracic cavity.

Open-label use of placebos in the treatment of ADHD: a pilot study

BACKGROUND

This study examined short-term efficacy, side effects and acceptability of a placebo treatment procedure designed to maintain children with attention deficit hyperactivity disorder (ADHD) on 50% of their usual stimulant dose.

METHODS

An open-label prospective crossover trial was conducted in 26 children with ADHD, ages 7-15 years, stable on stimulant therapy, followed at a community-based developmental paediatrics ADHD clinic. Subjects were randomly assigned to one of two orders of experimental conditions: (1) baseline (100%) dose (1 week), then 50% dose (1 week), then 50% dose + placebo (1 week), or (2) baseline (100%), then 50% dose + placebo, then 50% dose. The inert nature of the placebo was fully disclosed to parent and child. Treatment was open-label for child, parents and physician, but single blind for teachers. Main outcome measures included weekly IOWA Conners parent and teacher rating scales, the Pittsburgh side effects rating scale (PSERS) and the Clinical Global Impressions (CGI) scale.

RESULTS

Parent IOWA showed ADHD behaviour tended to remain the same when the dose of stimulant medication was reduced with placebo but to deteriorate when the dose was reduced without placebo. There were no significant differences between conditions on the Teacher IOWA. PSERS scores were higher at baseline than on 50% dose. On the CGI, there was a significant difference (P = 0.004) between the 50% dose and the 50% + placebo conditions. Individual subject analysis showed that eight subjects met criteria for responder.

CONCLUSIONS

Results indicate that the open-label placebo treatment was acceptable and efficacious in the short term for some children.

H-type congenital tracheoesophageal fistula: University Of Iowa experience 1985 to 2005

OBJECTIVES

We review the diagnostic workup, associated disorders, surgical technique, and postoperative course of patients who underwent repair of H-type tracheoesophageal fistulas.

METHODS

We performed a retrospective chart review of patients who received a diagnosis of tracheoesophageal fistula at the University of Iowa.

RESULTS

Seven patients with an H-type tracheoesophageal fistula and a single patient with a missed proximal fistula associated with esophageal atresia were identified. Their symptoms included coughing with feeding, recurrent pneumonia, and episodic cyanosis. A delay in diagnosis was seen in 4 patients and ranged from 2.5 months to 5.9 years. In all patients, the diagnosis was made with an esophagogram. The level of the fistulas was between C5 and T3, and all were successfully repaired via a right cervical approach.

CONCLUSIONS

A high index of suspicion for an H-type tracheoesophageal fistula should be maintained in the presence of neonatal respiratory symptoms, as the condition can be associated with a delay in diagnosis. Repeat esophagograms and bronchoscopy may be required for diagnosis. In the postoperative period, airway obstruction is a potential risk; however, long-term difficulty with swallowing, respiration, and phonation was not observed.

Experience with alternate sources of venous inflow in the meso-Rex bypass operation: the coronary and splenic veins

The meso-Rex bypass procedure has been used to treat patients with portal hypertension from extrahepatic portal vein obstruction. This report describes modifications of this procedure in 5 patients. Either the splenic or coronary vein was used as the venous inflow point, and the bypass was performed either directly through transposition of the vein or with the use of a venous conduit.