A case report of an asymptomatic necrotic Meckel's diverticulum in an inguinal hernia during elective surgery in a resource limited setting: Littre's hernia.

INTRODUCTION AND IMPORTANCE: Although the common complications of Meckel's diverticulum (MD) are well known, that these congenital intestinal outpouchings may become involved as the content of abdominal hernia sacs is not well appreciated. MD is the most prevalent congenital abnormality of the gastrointestinal tract, but involvement in a hernia, known as Littre's hernia (LH), accounts for less than 1 % of MD cases. Incarcerated LH has been reported sporadically in the literature, with MD found in the sacs of paraumbilical, femoral, inguinal, and incisional hernias. PRESENTATION OF CASE: We report a LH in a 3-year-old male child who was scheduled for elective herniotomy for a reducible left inguinal hernia. Intraoperatively we found the hernia sac contained a necrotic and perforated MD with viable associated bowel loop. The patient was successfully managed by diverticulectomy and primary repair through a trans-inguinal incision and herniotomy was performed. CLINICAL DISCUSSION: LH is a rare presentation of MD, and preoperative diagnosis of LH is challenging. Even in the case of a strangulated MD, a patient may not present with the typical signs and symptoms associated with compromised viscous. Once identified, repair of Littre hernia consists of resection of the diverticulum, or segmental bowel resection if necessary, and herniotomy. CONCLUSION: The finding of a perforated MD during elective hernia repair emphasizes the importance of awareness of unusual variants of inguinal hernia, and the necessity of identifying a MD given the risk of sequelae in the case of necrosis or perforation, if not repaired.

Effect of mechanical unloading on genome-wide DNA methylation profile of the failing human heart.

Heart failure (HF) is characterized by global alterations in myocardial DNA methylation, yet little is known about the epigenetic regulation of the noncoding genome and potential reversibility of DNA methylation with left ventricular assist device (LVAD) therapy. Genome-wide mapping of myocardial DNA methylation in 36 patients with HF at LVAD implantation, 8 patients at LVAD explantation, and 7 nonfailing (NF) donors using a high-density bead array platform identified 2,079 differentially methylated positions (DMPs) in ischemic cardiomyopathy (ICM) and 261 DMPs in nonischemic cardiomyopathy (NICM). LVAD support resulted in normalization of 3.2% of HF-associated DMPs. Methylation-expression correlation analysis yielded several protein-coding genes that are hypomethylated and upregulated (HTRA1, FBXO16, EFCAB13, and AKAP13) or hypermethylated and downregulated (TBX3) in HF. A potentially novel cardiac-specific super-enhancer long noncoding RNA (lncRNA) (LINC00881) is hypermethylated and downregulated in human HF. LINC00881 is an upstream regulator of sarcomere and calcium channel gene expression including MYH6, CACNA1C, and RYR2. LINC00881 knockdown reduces peak calcium amplitude in the beating human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). These data suggest that HF-associated changes in myocardial DNA methylation within coding and noncoding genomes are minimally reversible with mechanical unloading. Epigenetic reprogramming strategies may be necessary to achieve sustained clinical recovery from heart failure.

Validation of a Manual Negative Pressure Wound Therapy Device (PragmaVAC) for Acute and Chronic Wounds: A Prospective, Randomized, Controlled Trial.

BACKGROUND: Negative pressure wound therapy (NPWT) is an alternative to the standard gauze dressings for wound treatment. Due to limited health resources, poor electrical supply, and high costs, NPWT in resource-constrained settings is inaccessible. In conflict-affected settings, civilian injuries typically involve traumatic wounds or chronic wound infections that affect the extremities. METHODS: PragmaVAC® is a manually operated NPWT device designed to increase accessibility to NPWT without the need of electrical power. We aimed to determine the clinical efficacy of PragmaVAC through a controlled, non-blinded open-label clinical trial in a resource-constrained locality. The endpoint was formation of granulation tissue sufficient for wound closure. RESULTS: Fifty-nine patients qualified for analysis (19 Gauze; 40 PragmaVAC). The mean age of participants was 49.25 years, 55.9% were male, and 42.4% were diabetic. Forty three wounds (72.9%) were acute, 44 wounds (74.6%) were clean-contaminated, and 34 wounds (57.6%) were localized to the lower limb. The average duration of treatment was 15.3 days in PragmaVAC vs 36.5 days in control, p = 0.013. Similarly, PragmaVAC required fewer number of dressing changes 2.7 vs 23.2 times, p < 0.0001, at a lower frequency of dressings 0.22/day vs 0.73/day, in the control group, p < 0.0001. CONCLUSIONS: PragmaVAC is associated with accelerated healing and less frequent requirement of dressing changes. The introduction of a manually operated, low-cost device in resource-constrained settings presents an opportunity to improve wound care outcomes, decrease interventions, and optimize usage of material and human resources.

Changes in extracellular matrix in failing human non-ischemic and ischemic hearts with mechanical unloading.

Ischemic and non-ischemic cardiomyopathies have distinct etiologies and underlying disease mechanisms, which require in-depth investigation for improved therapeutic interventions. The goal of this study was to use clinically obtained myocardium from healthy and heart failure patients, and characterize the changes in extracellular matrix (ECM) in ischemic and non-ischemic failing hearts, with and without mechanical unloading. Using tissue engineering methodologies, we also investigated how diseased human ECM, in the absence of systemic factors, can influence cardiomyocyte function. Heart tissues from heart failure patients with ischemic and non-ischemic cardiomyopathy were compared to explore differential disease phenotypes and reverse remodeling potential of left ventricular assisted device (LVAD) support at transcriptomic, proteomic and structural levels. The collected data demonstrated that the differential ECM compositions recapitulated the disease microenvironment and induced cardiomyocytes to undergo disease-like functional alterations. In addition, our study also revealed molecular profiles of non-ischemic and ischemic heart failure patients and explored the underlying mechanisms of etiology-specific impact on clinical outcome of LVAD support and tendency towards reverse remodeling.

Horizontal transfer of the stemness-related markers EZH2 and GLI1 by neuroblastoma-derived extracellular vesicles in stromal cells.

Neuroblastoma (NB) is the most common extracranial pediatric solid cancer originating from undifferentiated neural crest cells. NB cells express EZH2 and GLI1 genes that are known to maintain the undifferentiated phenotype of cancer stem cells (CSC) in NB. Recent studies suggest that tumor-derived extracellular vesicles (EVs) can regulate the transformation of surrounding cells into CSC by transferring tumor-specific molecules they contain. However, the horizontal transfer of EVs molecules in NB remains largely unknown. We report the analysis of NB-derived EVs in bioengineered models of NB that are based on a collagen 1/hyaluronic acid scaffold designed to mimic the native tumor niche. Using these models, we observed an enrichment of GLI1 and EZH2 mRNAs in NB-derived EVs. As a consequence of the uptake of NB-derived EVs, the host cells increased the expression levels of GLI1 and EZH2. These results suggest the alteration of the expression profile of stromal cells through an EV-based mechanism, and point the GLI1 and EZH2 mRNAs in the EV cargo as diagnostic biomarkers in NB.

Barriers to Pediatric Surgical Care in Low-Income Countries: The Three Delays' Impact in Uganda.

BACKGROUND: We sought to understand the challenges in accessing pediatric surgical care in the context of the "three delays" model at the Pediatric Surgery Outpatient Clinic (PSOPC) at a tertiary hospital in Kampala, Uganda. MATERIALS AND METHODS: An outpatient database was established at the weekly PSOPC. A survey regarding prior healthcare visits and barriers to care was additionally administered to clinic patients and inpatients. RESULTS: Patients first sought healthcare a median of 56 d before the current visit to the PSOPC. A majority (52%) of patients first sought care at another health facility, and 17% of those surveyed had presented to the PSOPC three or more times for their current medical issue. Of 240 patients with a new issue or due for their next surgery, 10% were admitted to the ward, with only 54% receiving definitive care. Included in the most commonly needed surgeries for PSOPC patients were herniotomy (16% inguinal; 14.9% umbilical), orchiopexy (6.3%), posterior sagittal anorectoplasty (6.3%), and colostomy closure (4.4%), with the range of patient ages at the time of presentation reflecting delays in care. Patient expenditures associated with travel to the hospital showed inpatients coming from significantly further away, with higher costs of travel and need to borrow or sell assets to cover travel costs, when compared with PSOPC patients. CONCLUSIONS: Patients face significant delays in accessing and receiving definitive surgical care. Associated burdens associated with these delays place patients at risk for catastrophic health expenditures. Infrastructure and capacity development are necessary for improvement in pediatric surgical care.

Impact of incidental findings in preoperative CTA imaging for autologous breast reconstruction.

BACKGROUND: CT angiography (CTA) can be performed pre-operatively for perforator mapping in autologous breast reconstruction. The full impact of incidental CTA findings on breast reconstruction remains unclear. METHODS: CTAs were reviewed for all patients who underwent imaging prior to autologous breast reconstruction at Yale New Haven Hospital from 2013-2018. CTA findings and all resulting follow-up imaging, treatment, and change in management were catalogued. Our findings were compared to other published reports in the literature to better categorize the impact of CTA findings on patient care. RESULTS: Records from 341 patients were reviewed. One hundred fifty-four patients (45.2%) had incidental findings with 15.6% requiring further imaging or biopsy. Three patients (0.9%) underwent a change in management. One patient was diagnosed with metastatic disease prior to mastectomy. Another two patients required gynecologic procedures as a result of the CTA findings. Data was pooled with three other series in the literature for aggregate analysis of 959 operative planning CTAs. In total, incidental findings were present in 53.7% of patients. In the meta-analysis, 10.4% of patients required additional imaging or biopsy and 1.4% of screening CTAs impacted medical management. CONCLUSION: Pre-operative autologous breast reconstruction planning reveals incidental findings in approximately half of all imaging studies. In an analysis of nearly 1000 CTAs, patient care was impacted in 1.4% of cases. If imaging is obtained for planning purposes, the reconstructive microsurgeon should carefully review the full imaging report given its potential impact on patient care.

Myocardial Recovery in Patients Receiving Contemporary Left Ventricular Assist Devices: Results From the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS).

BACKGROUND: Time course and predictors of myocardial recovery on contemporary left ventricular assist device support are poorly defined because of limited number of recovery patients at any implanting center. This study sought to investigate myocardial recovery using multicenter data from the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS). METHODS AND RESULTS: Thirteen thousand four hundred fifty-four adult patients were studied. Device explant rates for myocardial recovery were 0.9% at 1-year, 1.9% at 2-year, and 3.1% at 3-year follow-up. Independent predictors of device explantation for recovery were age <50 years (odds ratio [OR] 2.5), nonischemic etiology (OR 5.4), time since initial diagnosis <2 years (OR 3.4), suboptimal heart failure therapy before implant (OR 2.2), left ventricular end-diastolic diameter <6.5 cm (OR 1.7), pulmonary systolic artery pressure <50 mm Hg (OR 2.0), blood urea nitrogen <30 mg/dL (OR 3.3), and axial-flow device (OR 7.6). Patients with myocarditis (7.7%), postpartum cardiomyopathy (4.4%), and adriamycin-induced cardiomyopathy (4.1%) had highest rates of device explantation for recovery. Use of neurohormonal blockers on left ventricular assist device support was significantly higher in patients who were explanted for recovery. Importantly, 9% of all left ventricular assist device patients who were not explanted for recovery have demonstrated substantial improvement in left ventricular ejection fraction (partial recovery) and had remarkable overlap in clinical characteristic profile compared with patients who were explanted for recovery (complete recovery). Complete and partial recovery rates have declined in parallel with recent changes observed in device indications and technology. CONCLUSIONS: Myocardial recovery is a spectrum of improvement rather than a binary clinical end point. One in every 10 left ventricular assist device patients demonstrates partial or complete myocardial recovery and should be targeted for functional assessment and optimization.

Recapitulating the Size and Cargo of Tumor Exosomes in a Tissue-Engineered Model.

There is a growing interest in the pivotal role of exosomes in cancer and in their use as biomarkers. However, despite the importance of the microenvironment for cancer initiation and progression, monolayer cultures of tumor cells still represent the main in vitro source of exosomes. As a result, their environmental regulation remains largely unknown. Here, we report a three-dimensional tumor model for studying exosomes, using Ewing's sarcoma type 1 as a clinically relevant example. The bioengineered model was designed based on the hypothesis that the 3-dimensionality, composition and stiffness of the tumor matrix are the critical determinants of the size and cargo of exosomes released by the cancer cells. We analyzed the effects of the tumor microenvironment on exosomes, and the effects of exosomes on the non-cancer cells from the bone niche. Exosomes from the tissue-engineered tumor had similar size distribution as those in the patients' plasma, and were markedly smaller than those in monolayer cultures. Bioengineered tumors and the patients' plasma contained high levels of the Polycomb histone methyltransferase EZH2 mRNA relatively to their monolayer counterparts. Notably, EZH2 mRNA, a potential tumor biomarker detectable in blood plasma, could be transferred to the surrounding mesenchymal stem cells. This study provides the first evidence that an in vitro culture environment can recapitulate some properties of tumor exosomes.

Physiologic force-frequency response in engineered heart muscle by electromechanical stimulation.

A hallmark of mature mammalian ventricular myocardium is a positive force-frequency relationship (FFR). Despite evidence of organotypic structural and molecular maturation, a positive FFR has not been observed in mammalian tissue engineered heart muscle. We hypothesized that concurrent mechanical and electrical stimulation at frequencies matching physiological heart rate will result in functional maturation. We investigated the role of biomimetic mechanical and electrical stimulation in functional maturation in engineered heart muscle (EHM). Following tissue consolidation, EHM were subjected to electrical field stimulation at 0, 2, 4, or 6 Hz for 5 days, while strained on flexible poles to facilitate auxotonic contractions. EHM stimulated at 2 and 4 Hz displayed a similarly enhanced inotropic reserve, but a clearly diverging FFR. The positive FFR in 4 Hz stimulated EHM was associated with reduced calcium sensitivity, frequency-dependent acceleration of relaxation, and enhanced post-rest potentiation. This was paralleled on the cellular level with improved calcium storage and release capacity of the sarcoplasmic reticulum and enhanced T-tubulation. We conclude that electro-mechanical stimulation at a physiological frequency supports functional maturation in mammalian EHM. The observed positive FFR in EHM has important implications for the applicability of EHM in cardiovascular research.

Bioengineering heart tissue for in vitro testing.

A classical paradigm of tissue engineering is to grow tissues for implantation by using human stem cells in conjunction with biomaterial scaffolds (templates for tissue formation) and bioreactors (culture systems providing environmental control). A reverse paradigm is now emerging through microphysiological platforms for preclinical testing of drugs and modeling of disease that contain large numbers of very small human tissues. We discuss the biomimetic approach as a common underlying principle and some of the specifics related to the design and utilization of platforms with heart micro-tissues for high-throughput screening in vitro.

Noninvasive imaging of myocyte apoptosis following application of a stem cell-engineered delivery platform to acutely infarcted myocardium.

UNLABELLED: The cardioprotective effects of mesenchymal stem cells (MSCs) include reducing myocyte apoptosis, and this effect can be enhanced by preconditioning and encapsulation in a fibrin scaffold. This study aimed to test the hypothesis that apoptosis imaging can detect the cardioprotective effects of a conditioned MSC patch grafted in a rat model of acute myocardial infarction. METHODS: Cell culture experiments simulating engraftment of fibrin patches onto beating rat ventricular myocytes exposed to hypoxia showed an effect of conditioned cells to reduce apoptosis. Twenty-three nude rats underwent successful left anterior descending coronary artery occlusion and were divided into 3 groups: transforming growth factor ß1-conditioned human MSC-laden patches (CP), infarct alone without patch (no patch [NP]), and patch alone (patch only [PO]). Twenty-four hours after myocardial infarction, all rats were injected with (99m)Tc-hydrazinonicotinamide ((99m)Tc-HYNIC) annexin V and (201)Tl and underwent dual-isotope SPECT/CT imaging. Six rats were sacrificed for histology and counting. The remaining rats (n = 17; 1 rat was eliminated) were injected and imaged on day 7; of those, 3 rats were sacrificed for histology and counting, and the remaining 13 rats survived to day 21, when they were sacrificed for histology. Numbers of rats imaged on day 7 in the 3 groups were 7 in the CP group, 5 in the NP, and 5 in the PO. Perfused myocardium, infarct size, and (99m)Tc-HYNIC annexin V uptake were quantified from the scans from days 1 and 7. (99m)Tc-HYNIC annexin V uptake was correlated with quantitative caspase staining, and infarct size as percentage fibrosis was quantified at day 21. RESULTS: (99m)Tc-HYNIC annexin V uptake as percentage injected dose (×10(-4)) decreased between days 1 and 7 by 1.04 ± 0.28 in the CP group, 0.44 ± 0.17 in the NP group, and 0.34 ± 0.27 in the PO group (P = 0.003 for NP vs. CP, P = 0.005 for PO vs. CP, and P = 0.5 for NP vs. CP). The changes in defect size as percentage myocardium between days 1 and 7 were -8.83 ± 4.40 in the CP group, +1.00 ± 2.24 in the NP group, and -0.50 ± 4.20 in the PO group (P = 0.003 for NP vs. CP, P = 0.005 for PO vs. CP, and P = 0.50 for NP vs. PO). (99m)Tc-HYNIC annexin V uptake as percentage left ventricle by scanning correlated with caspase staining (r = 0.931, P = 0.002). CONCLUSION: Transforming growth factor ß1-conditioned human MSC-laden patches reduce myocyte apoptosis in the setting of acute infarction, and this effect can be detected by in vivo imaging with (99m)Tc-HYNIC annexin V.

Composite scaffold provides a cell delivery platform for cardiovascular repair.

Control over cell engraftment, survival, and function remains critical for heart repair. We have established a tissue engineering platform for the delivery of human mesenchymal progenitor cells (MPCs) by a fully biological composite scaffold. Specifically, we developed a method for complete decellularization of human myocardium that leaves intact most elements of the extracellular matrix, as well as the underlying mechanical properties. A cell-matrix composite was constructed by applying fibrin hydrogel with suspended cells onto decellularized sheets of human myocardium. We then implanted this composite onto the infarct bed in a nude rat model of cardiac infarction. We next characterized the myogenic and vasculogenic potential of immunoselected human MPCs and demonstrated that in vitro conditioning with a low concentration of TGF-ß promoted an arteriogenic profile of gene expression. When implanted by composite scaffold, preconditioned MPCs greatly enhanced vascular network formation in the infarct bed by mechanisms involving the secretion of paracrine factors, such as SDF-1, and the migration of MPCs into ischemic myocardium, but not normal myocardium. Echocardiography demonstrated the recovery of baseline levels of left ventricular systolic dimensions and contractility when MPCs were delivered via composite scaffold. This adaptable platform could be readily extended to the delivery of other reparative cells of interest and used in quantitative studies of heart repair.