The fabrication of PLGA-Fe3O4- magnetic nanoparticles for targeted delivery of γ-secretase inhibitors to vascular stents

Cardiovascular disease is the number one killer in Ireland and the wider EU. A hallmark of the disease is the obstruction to blood flow due to the build-up of neointimal vascular smooth muscle (SMCs)-like cells within the vessel wall. Several groups have shown SMC-like cells play important roles in the pathophysiological processes of arteriosclerosis, atherosclerosis, and in-stent restenosis [ISR]. Our lab and others have shown a putative role for re-capitulation of Notch signalling components in arteriosclerosis progression. Lately, multipotent vascular stem cells (MVSCs) have been isolated and shown to proliferate and differentiate into SMCs, causing vascular injury in animal models. Therefore, targeting these cells is an attractive therapeutic strategy for treating vascular remodelling disorders. In-stent restenosis treatment options include percutaneous transluminal coronary angioplasty (PTCA) and intravascular stenting yet a significant number of stented vessels may become re-occluded due to ISR. While polymer-coated drug-eluting stents (DES) have significantly reduced the incidence of ISR, current DESs have limitations. This limitation can be overcome by combining magnetic targeting via a uniform field-induced magnetization effect and a biocompatible magnetic nanoparticle (MNP) formulation designed for efficient entrapment and delivery of a specific drug that targets resident multipotent vascular stem cells (MVSCs). Therefore, the overall aim of this thesis was to develop a method for targeting vascular stents using nanotechnology. Specifically, the aim was to (i) fabricate magnetic nanoparticles (MNP’s) containing magnetite (Fe3O4) and functionalised with poly (DL-lactide-co-glycolide) polyvinyl alcohol [PLGA-PVA], (ii) characterise their functional properties, targeting to vascular stents and drug-release kinetics following the entrapment of two drugs, DAPT and Compound E, both of which are Ɣ-secretase inhibitors (GSI) of Notch target gene expression (iii) determine the effects of MNPs loaded with Ɣ-secretase inhibitors (DAPT and Compound E) on the growth and myogenic differentiation capacity of resident vascular stem cells under non- magnetic and magnetic conditions in vitro. The DAPT-loaded MNPs had an average hydrodynamic diameter of 351 d.nm. Up to 68% and 98% of the drug was incorporated into MNPs after one week under magnetic conditions. The Notch ligand, Jagged1 increased Hey1 mRNA levels and promoted myogenic differentiation of MSCs in vitro by increasing SMC differentiation markers, myosin heavy chain 11 (Myh11) and calponin1 (CNN1) expression, respectively. This effect was significantly attenuated following treatment of cells with both MNP’s loaded with DAPT and MNP’s loaded with Compound E when compared to unloaded MNP’s. These data suggest that Notch GSI loaded magnetic nanoparticles are functional at vascular stem cells in vitr

The fabrication of PLGA-Fe3O4- magnetic nanoparticles for targeted delivery of γ-secretase inhibitors to vascular stents

Cardiovascular disease is the number one killer in Ireland and the wider EU. A hallmark of the disease is the obstruction to blood flow due to the build-up of neointimal vascular smooth muscle (SMCs)-like cells within the vessel wall. Several groups have shown SMC-like cells play important roles in the pathophysiological processes of arteriosclerosis, atherosclerosis, and in-stent restenosis [ISR]. Our lab and others have shown a putative role for re-capitulation of Notch signalling components in arteriosclerosis progression. Lately, multipotent vascular stem cells (MVSCs) have been isolated and shown to proliferate and differentiate into SMCs, causing vascular injury in animal models. Therefore, targeting these cells is an attractive therapeutic strategy for treating vascular remodelling disorders. In-stent restenosis treatment options include percutaneous transluminal coronary angioplasty (PTCA) and intravascular stenting yet a significant number of stented vessels may become re-occluded due to ISR. While polymer-coated drug-eluting stents (DES) have significantly reduced the incidence of ISR, current DESs have limitations. This limitation can be overcome by combining magnetic targeting via a uniform field-induced magnetization effect and a biocompatible magnetic nanoparticle (MNP) formulation designed for efficient entrapment and delivery of a specific drug that targets resident multipotent vascular stem cells (MVSCs). Therefore, the overall aim of this thesis was to develop a method for targeting vascular stents using nanotechnology. Specifically, the aim was to (i) fabricate magnetic nanoparticles (MNP’s) containing magnetite (Fe3O4) and functionalised with poly (DL-lactide-co-glycolide) polyvinyl alcohol [PLGA-PVA], (ii) characterise their functional properties, targeting to vascular stents and drug-release kinetics following the entrapment of two drugs, DAPT and Compound E, both of which are Ɣ-secretase inhibitors (GSI) of Notch target gene expression (iii) determine the effects of MNPs loaded with Ɣ-secretase inhibitors (DAPT and Compound E) on the growth and myogenic differentiation capacity of resident vascular stem cells under non- magnetic and magnetic conditions in vitro. The DAPT-loaded MNPs had an average hydrodynamic diameter of 351 d.nm. Up to 68% and 98% of the drug was incorporated into MNPs after one week under magnetic conditions. The Notch ligand, Jagged1 increased Hey1 mRNA levels and promoted myogenic differentiation of MSCs in vitro by increasing SMC differentiation markers, myosin heavy chain 11 (Myh11) and calponin1 (CNN1) expression, respectively. This effect was significantly attenuated following treatment of cells with both MNP’s loaded with DAPT and MNP’s loaded with Compound E when compared to unloaded MNP’s. These data suggest that Notch GSI loaded magnetic nanoparticles are functional at vascular stem cells in vitr

Enteral Nutrition Prescription in Children and Adults with Inflammatory Bowel Diseases: Gaps in Current Gastroenterology Practice in Saudi Arabia

Background: Evidence for the effectiveness of enteral nutrition (EN) for the management of patients with inflammatory bowel disease (IBD) is well-established. However, there is considerable global variation in EN practices. This study aimed to characterize the practices and perceptions of gastroenterologists regarding the use of EN in patients with IBD in one of the largest countries in the Gulf region. Methods: A cross-sectional study was conducted on pediatric and adult gastroenterologists working in Saudi Arabia who are involved in IBD management. A self-administered web-based survey was distributed via social media platforms and mailing lists of national gastroenterology societies. Results: A total of 80 gastroenterologists completed the survey. However, only 55 reported that they were currently practicing EN in any form. EN was mostly indicated by gastroenterologists who “sometimes” recommend EN for: the prevention and correction of undernutrition (50.9%), preoperative optimization (50.9%), and the induction of remission in patients with active and long-standing CD (36.4%), at initial diagnosis (34.5%), during the management of complications (61.8%), and after failing to respond to pharmacological therapy (58.2%). Exclusive enteral nutrition (EEN) is regularly recommended by 14.5% of gastroenterologists. The prescription of EEN was significantly associated with the pediatric profession (p p p p < 0.01). The most reported barriers to using EN were patients’ lack of acceptance (73.8%) and poor adherence (65%). A lack of dietitian support and a lack of standardized protocols were also reported as barriers by many physicians. Pediatric gastroenterologists were more likely to use at least one assessment method to evaluate EN success. Conclusion: EN practices differ between gastroenterologists working in Saudi Arabia. Future EN protocols should be optimized to support both children and adults with IBD. Gastroenterology training programs should offer nutrition support-focused training to help physicians better utilize EN

Thymoquinone Enhances Paclitaxel Anti-Breast Cancer Activity via Inhibiting Tumor-Associated Stem Cells Despite Apparent Mathematical Antagonism

Thymoquinone (TQ) has shown substantial evidence for its anticancer effects. Using human breast cancer cells, we evaluated the chemomodulatory effect of TQ on paclitaxel (PTX). TQ showed weak cytotoxic properties against MCF-7 and T47D breast cancer cells with IC50 values of 64.93 &plusmn; 14 &micro;M and 165 &plusmn; 2 &micro;M, respectively. Combining TQ with PTX showed apparent antagonism, increasing the IC50 values of PTX from 0.2 &plusmn; 0.07 &micro;M to 0.7 &plusmn; 0.01 &micro;M and from 0.1 &plusmn; 0.01 &micro;M to 0.15 &plusmn; 0.02 &micro;M in MCF-7 and T47D cells, respectively. Combination index analysis showed antagonism in both cell lines with CI values of 4.6 and 1.6, respectively. However, resistance fractions to PTX within MCF-7 and T47D cells (42.3 &plusmn; 1.4% and 41.9 &plusmn; 1.1%, respectively) were completely depleted by combination with TQ. TQ minimally affected the cell cycle, with moderate accumulation of cells in the S-phase. However, a significant increase in Pre-G phase cells was observed due to PTX alone and PTX combination with TQ. To dissect this increase in the Pre-G phase, apoptosis, necrosis, and autophagy were assessed by flowcytometry. TQ significantly increased the percent of apoptotic/necrotic cell death in T47D cells after combination with paclitaxel. On the other hand, TQ significantly induced autophagy in MCF-7 cells. Furthermore, TQ was found to significantly decrease breast cancer-associated stem cell clone (CD44+/CD24-cell) in both MCF-7 and T47D cells. This was mirrored by the downregulation of TWIST-1 gene and overexpression of SNAIL-1 and SNAIL-2 genes. TQ therefore possesses potential chemomodulatory effects to PTX when studied in breast cancer cells via enhancing PTX induced cell death including autophagy. In addition, TQ depletes breast cancer-associated stem cells and sensitizes breast cancer cells to PTX killing effects

Prototype Development of a Temperature-Sensitive High-Adhesion Medical Tape to Reduce Medical-Adhesive-Related Skin Injury and Improve Quality of Care

Medical adhesives are used to secure wound care dressings and other critical devices to the skin. Without means of safe removal, these stronger adhesives are difficult to painlessly remove from the skin and may cause medical-adhesive-related skin injuries (MARSI), including skin tears and an increased risk of infection. Lower-adhesion medical tapes may be applied to avoid MARSI, leading to device dislodgement and further medical complications. This paper outlines the development of a high-adhesion medical tape designed for low skin trauma upon release. By warming the skin-attached tape for 10–30 s, a significant loss in adhesion was achieved. A C14/C18 copolymer was developed and combined with a selected pressure-sensitive adhesive (PSA) material. The addition of 1% C14/C18 copolymer yielded the largest temperature-responsive drop in surface adhesion. The adhesive film was characterized using AFM, and distinct nanodomains were identified on the exterior surface of the PSA. Our optimized formulation yielded 67% drop in adhesion when warmed to 45 °C, perhaps due to melting nanodomains weakening the adhesive–substrate boundary layer. Pilot clinical testing resulted in a significant decrease in pain when a heat pack was used for removal, giving an average pain reduction of 66%