The fabrication of PLGA-Fe3O4- magnetic nanoparticles for targeted delivery of γ-secretase inhibitors to vascular stents
Bashmail, Roa
(2019)
The fabrication of PLGA-Fe3O4- magnetic nanoparticles for targeted delivery of γ-secretase inhibitors to vascular stents.
Doctor of Science thesis, Dublin City University.
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 vitro