Gene and cell therapy approaches for treatment of cardiovascular disease

We are interested in developing novel therapies for patients with heart disease. Specifically, patients who undergo coronary artery bypass grafting or undergo implantation of stents. Both these procedures have the potential complication of blood vessel blockage following the grafting or stent implantation and this limits the effectiveness of the therapy. Our strategies are to develop novel therapies that prevent this process and can be delivered at the same time as the procedure is performed, thus providing lasting benefit to patients. We test specific genes and new molecules called “microRNA” in this context and evaluate them in accepted models of disease and in human tissue.

Human embryonic stem cells and induced pluripotent stem cells (iPS) hold broad potential in regenerative medicine. Such cells can generate all cell types upon stimulation to differentiate along defined cell commitment pathways. We are interested in the mechanisms that govern stimulation of these cells into vascular endothelial cells and their subsequent application to regenerative medicine. When cells are stimulated in this way certain “pathways” are activated and new genes are transcribed from DNA into RNA and then to protein. We are particularly interested in finding out what controls these steps and in this project we will address this important issue and, importantly, manipulate them to refine and optimise cardiac and vascular endothelium commitment.

Gene therapy vector development

(Baker, Nicklin)

Research within the virology theme focuses primarily upon the development of genetically manipulated adenoviral vectors (primarily based on Ad5) for gene therapy applications in cardiovascular disease. Our work characterises the interactions occurring between virus and host proteins and cells that define adenoviral tropism, toxicity and fate following intravenous administration. Of particular importance to our work has been defining and precluding the high affinity interaction between the Ad5 hexon protein and blood clotting factor X (FX, see figure 1 below). This interaction underpins the profound liver tropism of Ad5 based vectors following intravenous administration by retargeting the Ad5: FX complex to a particularly sulphated form of heparan sulphate proteoglygcan receptor, expressed abundantly upon liver hepatocytes. Ongoing research within our group seeks to build upon Ad5 based vectors genetically engineered to ablate FX binding to retarget them to alternative disease restricted receptors, as well as investigating the potential of new forms of adenoviruses for therapeutic applications.

 

Figure 1:  Computaional reconstruction of CryoEM images of Ad5 alone (cyan, resolved to 26Å, A&C), Ad5 in complex with FX (magenta, resolved to 23Å, B&D), and the composite image (E&F) demonstrating the FX binding to the hexon hypervariable regions (HVRs).

Gene Therapy Vector Development References

 

Vascular Remodeling & Therapy

(Baker, Nicklin, Berry)

The migration and proliferation of vascular smooth muscle cells are central to the development of neointima formation associated with late vein graft failure and in-stent restenosis (ISR). Over the past 10 years we have developed and evaluated, in relevant models and human tissues, effective strategies to prevent neointima formation by genetic manipulation of the vasculature leading to a potential clinical trial, based on adenovirus-mediated gene delivery of tissue inhibitors of metalloproteinase-3 (TIMP-3) to human saphenous vein. We are developing our detailed knowledge of adenoviral biology and engineering to construct and optimise the next generation of systems for vascular intervention studies. Previously studied mechanisms to manipulate the virus capsid in order to optimise vascular gene delivery and minimise dissemination and inflammation are integrated into single component viruses. We are pursuing both known (gene-based) and novel (miRNA-based) interventions to fully assess the safety and efficacy of such approaches in large animal and human tissue models of bypass graft failure and in-stent restenosis. 

 

Figure 2:  A.  First-generation Ad mediated expression of lacZ in porcine vein grafts, 7 days post grafting.  (George SJ et al.  Circulation 2000;101:269-304) B. Long term efficacy of First-generation Ad mediated over-expression of TIMP3 in porcine vein grafts. C. TIMP3 expression significantly reduced neointimal formation 3 months post grafting.  n=11-15 grafts/group.  George, Wan and Baker, unpublished

Vascular Gene Therapy References

 

Stem Cell Therapy

(Baker, Mountford, Milligan)

Revascularisation of underperfused tissues remains one of the biggest priorities in cardiovascular therapeutics. One focus has been the omnipotence of human embryonal stem cells (hESC) and their ability to form vascular endothelial cells (EC). Our published protocol for feeder- and serum-free monolayer hESC-EC-directed differentiation represents an optimal tool for the attainment of hESC-derived EC in a GMP-compliant manner for clinical trial purposes (Kane et al. 2010).

In collaboration with Roslin Cells Ltd., funded by the Technology Strategy Board for “the clinical translation of endothelial cells derived from human embryonic stem cells”, we were in the position to transfer aforementioned protocol and successfully differentiate GMP-derived Roslin hESC lines towards EC.

 

Figure 3: Stepwise development of hESC-derived endothelial cells.  Upper panel: morphological changes from d0 to d21 from left to right.  Middle and lower panel: time-matched immunofluorescent staining for endothelial markers VE-Cadherin and PECAM-1.

Stem Cell Therapy References

 

Publications

Gene Therapy Vector Development

Vascular Remodelling and Therapy

Stem Cell Therapy