Modeling the diffusion of nitric oxide produced by neuronal cells in brain ischemia

Optimizing endothelial cell functionalization for cell therapy of vascular proliferative disease using a direct contact co-culture system

Increased susceptibility to thrombosis, neoatherosclerosis, and restenosis due to incomplete regrowth of the protective endothelial layer remains a critical limitation of the interventional strategies currently used clinically to relieve atherosclerotic obstruction. Rapid recovery of endothelium holds promise for both preventing the thrombotic events and reducing post-angioplasty restenosis, providing the rationale for developing cell delivery strategies for accelerating arterial reendothelialization. The successful translation of experimental cell therapies into clinically viable treatment modalities for restoring vascular endothelium critically depends on identifying strategies for enhancing the functionality of endothelial cells (EC) derived from high cardiovascular risk patients, the target group for the majority of angioplasty procedures. Enhancing EC-associated nitric oxide (NO) synthesis by inducing overexpression of NO synthase (NOS) has shown promise as a way of increasing paracrine activity and restoring function of EC. In the present study, we developed a direct contact co-culture approach compatible with highly labile effectors, such as NO, and applied it for determining the effect of EC functionalization via NOS gene transfer on the growth of co-cultured arterial smooth muscle cells (A10 cell line) exhibiting the defining characteristics of neointimal cells. Bovine aortic endothelial cells magnetically transduced with inducible NOS-encoding adenovirus (Ad) formulated in zinc oleate-based magnetic nanoparticles (MNP[_iNOSAd]) strongly suppressed growth of proliferating A10 and attenuated the stimulatory effect of a potent mitogen, platelet-derived growth factor (PDGF-BB), whereas EC functionalization with free _iNOSAd or MNP formulated with a different isoform of the enzyme, endothelial NOS, was associated with lower levels of NO synthesis and less pronounced antiproliferative activity toward co-cultured A10 cells. These results show feasibility of applying magnetically facilitated gene transfer to potentiate therapeutically relevant effects of EC for targeted cell therapy of restenosis. The direct contact co-culture methodology provides a sensitive and reliable tool with potential utility for a variety of biomedical applications.

3-D Modeling of nitric oxide emission and vasodilation induced by CA3 hippocampal neurons

The modeling of the spread, diffusion, and decay of chemicals in the brain is a complex problem that is made difficult by the fact that the structures that produce chemicals (synapses etc.) may be very small in comparison to their radii of chemical influence. In this article, we concentrate on modeling a simple instance of this problem; that of a proficiently diffusing molecule that may cause changes in smooth muscle contractions over relatively large areas. An optimized diffusion system was developed to study the diffusion of neuronal nitric oxide. Our diffusion system allows us to model the spread of nitric oxide from all areas of neurons, including the soma and dendritic processes. In addition, our system allows us to model tiny diffusing structures without sacrificing large-scale granularity. To study the effect of NO-producing neurons on vasodilation, we simulate systems of 1 and 2 neurons. We show that it is possible for nitric oxide emitted from neurons to be involved in regulating blood flow.