Targeted mapping and utilization of the perihepatic surface for therapeutic beta cell replacement and retrieval in diabetic non-human primates.

Introduction: Successful diabetes reversal using pancreatic islet transplantation by various groups illustrates the significant achievements made in cell-based diabetes therapy. While clinically, intraportal islet delivery is almost exclusively used, it is not without obstacles, including instant blood-mediated inflammatory reaction (IBMIR), relative hypoxia, and loss of function over time, therefore hindering long-term success. Here we demonstrate the perihepatic surface of non-human primates (NHPs) as a potential islet delivery site maximizing favorable characteristics, including proximity to a dense vascular network for adequate oxygenation while avoiding IBMIR exposure, maintenance of portal insulin delivery, and relative ease of accessibility through minimally invasive surgery or percutaneous means. In addition, we demonstrate a targeted mapping technique of the perihepatic surface, allowing for the testing of multiple experimental conditions, including a semi-synthetic hydrogel as a possible three-dimensional framework to improve islet viability. Methods: Perihepatic allo-islet cell transplants were performed in immunosuppressed cynomolgus macaques using a targeted mapping technique to test multiple conditions for biocompatibility. Transplant conditions included islets or carriers (including hydrogel, autologous plasma, and media) alone or in various combinations. Necropsy was performed at day 30, and histopathology was performed to assess biocompatibility, immune response, and islet viability. Subsequently, single-injection perihepatic allo-islet transplant was performed in immunosuppressed diabetic cynomolgus macaques. Metabolic assessments were measured frequently (i.e., blood glucose, insulin, C-peptide) until final graft retrieval for histopathology. Results: Targeted mapping biocompatibility studies demonstrated mild inflammatory changes with islet-plasma constructs; however, significant inflammatory cell infiltration and fibrosis were seen surrounding sites with the hydrogel carrier affecting islet viability. In diabetic NHPs, perihepatic islet transplant using an autologous plasma carrier demonstrated prolonged function up to 6 months with improvements in blood glucose, exogenous insulin requirements, and HbA1c. Histopathology of these islets was associated with mild peri-islet mononuclear cell infiltration without evidence of rejection. Discussion: The perihepatic surface serves as a viable site for islet cell transplantation demonstrating sustained islet function through 6 months. The targeted mapping approach allows for the testing of multiple conditions simultaneously to evaluate immune response to biomaterials at this site. Compared to traditional intraportal injection, the perihepatic site is a minimally invasive approach that allows the possibility for graft recovery and avoids IBMIR.

A bioengineered artificial interstitium supports long-term islet xenograft survival in nonhuman primates without immunosuppression.

Cell-based therapies hold promise for many chronic conditions; however, the continued need for immunosuppression along with challenges in replacing cells to improve durability or retrieving cells for safety are major obstacles. We subcutaneously implanted a device engineered to exploit the innate transcapillary hydrostatic and colloid osmotic pressure generating ultrafiltrate to mimic interstitium. Long-term stable accumulation of ultrafiltrate was achieved in both rodents and nonhuman primates (NHPs) that was chemically similar to serum and achieved capillary blood oxygen concentration. The majority of adult pig islet grafts transplanted in non-immunosuppressed NHPs resulted in xenograft survival >100 days. Stable cytokine levels, normal neutrophil to lymphocyte ratio, and a lack of immune cell infiltration demonstrated successful immunoprotection and averted typical systemic changes related to xenograft transplant, especially inflammation. This approach eliminates the need for immunosuppression and permits percutaneous access for loading, reloading, biopsy, and recovery to de-risk the use of "unlimited" xenogeneic cell sources to realize widespread clinical translation of cell-based therapies.

Technical Considerations and Approach to Redo Foregut Surgery.

Foregut surgical techniques have advanced significantly over the years and have become increasingly popular. However, new challenges and technical considerations have arisen when dealing with reoperation for complications or surgical failure. This study focuses on the technical considerations and approach when dealing with reoperative foregut surgery, particularly redo hiatal hernia repair. We describe our approach starting from the preoperative workup to the procedural steps of the surgery. The present study describes the main steps for robotic reoperative hiatal hernia repair in a patient who had previously undergone laparoscopic hiatal hernia repair with Nissen fundoplication but did not present a recurrence of reflux and dysphagia symptoms. The patient is positioned supine with arms out and a footboard for steep Trendelenburg. We place six trocars, including an assistant port and a liver retractor port, to facilitate visualization and retraction. After docking the robot, we use a combination of electrocautery and sharp dissection to free the hernia sac and reduce the hiatal hernia. The previous fundoplication is then taken down carefully and the esophagus is mobilized through a transhiatal approach with a combination of blunt and sharp dissection until at least 3 cm of intra-abdominal esophageal length is achieved, after which a leak test is performed. We then perform a crural repair to reapproximate the hiatus with two posterior stitches and one anterior stitch. Lastly, a redo Nissen fundoplication is performed over a bougie, and endoscopy is used to confirm a loose stack-of-coin appearance. By emphasizing the crucial steps of redo hiatal hernia repair, including preoperative evaluation, our goal is to provide an approach for the foregut surgeon to maximize patient outcomes.

Suture Tape With Broad Full-Width Core Versus Traditional Round Suture With Round Core: A Mechanical Comparison.

PURPOSE: To compare the inherent mechanical properties of suture in tape configuration with a flat, evenly distributed core to a round suture with a round core composed of the same materials. METHODS: SutureTape and FiberWire composed of equivalent materials were used to tie surgical knots. Knot height was measured. Knot security was measured at the maximum load at 1, 2, and 3 mm of displacement and at failure. Tensile strength and stiffness were measured using untied samples. RESULTS: SutureTape demonstrated superior knot security with greater ultimate load to failure (327.2 ± 15.4 N vs 257.4 ± 12.2 N; P = .002), maximum load at 1 mm of displacement (149.8 ± 18.6 N vs 108.8 ± 13.8 N; P = .001), and 2 mm of displacement (242.7 ± 38.6 N vs 181.2 ± 24.4 N; P = .008). It also demonstrated greater stiffness (5.4 ± 0.3 N/mm vs 2.8 ± 0.3 N/mm; P < .001) and tensile strength (378.8 ± 13.6 N vs 235.6 ± 4.8 N). Knot height differences (1.27 ± .11 mm vs 1.37 ± .08 mm; P = .110) and load at 3 mm of displacement (279.3 ± 42.4 N vs 225.5 ± 46.1 N; P = .062) were not statistically significant. CONCLUSIONS: During mechanical testing, SutureTape with a broad core distributed over the full width of the tape demonstrated greater knot security, ultimate load to failure, and tensile stiffness than FiberWire, a round core suture. We found no significant difference in knot stack height between the suture designs. CLINICAL RELEVANCE: The study demonstrates the superior mechanical properties of suture in tape configuration over similarly composed round suture without a significant difference in knot stack height. Suture in tape configuration has the potential to perform as well as round suture in the clinical setting.

Fowl Aviadenovirus 9 dUTPase Plays a Role in Regulation of the Host Immune Response.

Fowl aviadenoviruses (FAdVs) are distributed worldwide in poultry farms. Some FAdVs are the causative agents of inclusion body hepatitis and hydropericardium syndrome that cause significant economic losses to the poultry industry. In contrast with human adenovirus, the study of the molecular biology of FAdV is still far behind. We previously showed that FAdV-9 open reading frame 1 (ORF1) is a dUTPase enzyme that contributes to the upregulation of type I interferons and is not required for virus replication in vitro. In the present study, we compared virus replication in vivo and the host immune response in chickens orally inoculated with a dUTPase knockout virus (ORF1stop), the rescued version of ORF1stop (resORF1), and wtFAdV-9. Our data showed that replication of ORF1stop was delayed on days 1 and 3 postinoculation compared with wtFAdV-9, as evidenced by significantly less virus shedding in feces and lower viral loads in tissues. Moreover, we found that there was a significant difference in the induction of cytokine gene mRNA expression in tissues and IgG antibody responses in ORF1stop versus wtFAdV-9-infected chickens, suggesting that ORF1 plays some roles in modulating the host immune response. Our study provides useful data on the mechanism of the host immune response against FAdV infection.

Replication and Oncolytic Activity of an Avian Orthoreovirus in Human Hepatocellular Carcinoma Cells.

Oncolytic viruses are cancer therapeutics with promising outcomes in pre-clinical and clinical settings. Animal viruses have the possibility to avoid pre-existing immunity in humans, while being safe and immunostimulatory. We isolated an avian orthoreovirus (ARV-PB1), and tested it against a panel of hepatocellular carcinoma cells. We found that ARV-PB1 replicated well and induced strong cytopathic effects. It was determined that one mechanism of cell death was through syncytia formation, resulting in apoptosis and induction of interferon stimulated genes (ISGs). As hepatitis C virus (HCV) is a major cause of hepatocellular carcinoma worldwide, we investigated the effect of ARV-PB1 against cells already infected with this virus. Both HCV replicon-containing and infected cells supported ARV-PB1 replication and underwent cytolysis. Finally, we generated in silico models to compare the structures of human reovirus- and ARV-PB1-derived S1 proteins, which are the primary targets of neutralizing antibodies. Tertiary alignments confirmed that ARV-PB1 differs from its human homolog, suggesting that immunity to human reoviruses would not be a barrier to its use. Therefore, ARV-PB1 can potentially expand the repertoire of oncolytic viruses for treatment of human hepatocellular carcinoma and other malignancies.