TRANSLATING HUMAN EMBRYONIC STEM CELL-DERIVED ENDOTHELIAL CELL THERAPY TO THE CLINIC

Human embryonic stem (hES) 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. These cells line all blood vessels and have the capacity to induce blood vessel growth upon injection into the body. We have recently published a study that shows the potential of human endothelial cells derived from human embryonic stem cells (Kane et al., ATVB, 2010). We showed a very efficient production of endothelial cells in just 10 days following initiation of differentiation from the original hES cells. This rapid system induced robust changes, i.e. very effective reduction in pluripotency markers and induction of endothelial selective markers. We also defined the "therapeutic" potential of these cells in cell cultures and in animal models by demonstrating the induction of new blood vessel growth leading to better blood flow in the muscle that was damaged. The induction of this phenotype suggests that these cells and this differentiation system may be useful clinically in the treatment of ischemic conditions in patients with cardiovascular disease. In previous funding that ended recently, we were able to produce endothelial cells from hES cells at clinical grade thus showing proof of concept that these cells can be produced at the quality and quantity required for potential clinical use. This is a powerful approach that has not been tested in man yet. This is our aim for the present grant application.

In this proposal we will address a very important issue that now is required for further development of this product towards a first application in man. We require this grant funding to complete development of the cells at a grade acceptable for clinical use. We will further refine the protocol for production, fully test the cells produced in cell culture and by detailed analysis. We will then test the safety the cells and how good they are at inducing blood vessel growth in two important animal models, in mouse and rabbit. Finally, we will assess where the cells go after injection looking at retention in the tissue, dissemination to other tissues and organs and how long they stay there. These are important issues that will allow us to gain regulatory approval if the grant is successful.

Human embryonic stem (hES) cells and induced pluripotent stem (iPS) cells hold broad potential in regenerative medicine. Such stem 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 stem cells into vascular ECs and their subsequent application to regenerative medicine. We have recently published studies that show the potential of human ECs derived from hES cells (Kane et al., ATVB, 2010; Stem Cells., 2012). We showed a very efficient production of ECs in just 10 days following initiation of differentiation. This rapid system induced robust changes, i.e. very effective reduction in pluripotency markers and induction of endothelial selective markers. We also defined the "therapeutic" potential of these cells in cell cultures and in vivo by demonstrating the induction of angiogenesis and blood flow improvement in a mouse model of limb ischaemia. These results suggest that these cells and this differentiation system may be useful clinically in the treatment of ischaemic conditions in patients with cardiovascular disease. This present application builds upon pilot data showing that we can generate human endothelial cells from hES cell lines under GMP-compliant conditions (achieved through TSB funding). We now wish to develop this translational agenda towards a first-in-man trial through careful assessment of these cells. This will be achieved by final protocol optimisation and validation, safety studies, efficacy and biodistribution studies. This will be conducted by bringing together key researchers to work together towards this goal.

Baker (as PI in Glasgow), Emanueli (as PI in Bristol) and Newby (as PI in Edinburgh) will deliver this project. We envisage that if this is funded and is successful we will move towards a first-in-man trial and thus demonstrates how our work in the development of stem cells in the pre-clinical phases enables potential translation to humans. The ultimate beneficiaries will be patients who will benefit from improved treatments for cardiovascular disease (in particular critical limb ischemia but also myocardial infarction) through generation of a novel therapy that has the potential for lasting impact. The benefit will come through improved knowledge of hES/iPS therapies, especially clinical grade production of cells (GMP). Ultimately, this (if successful) will lead to a substantial impact on healthcare. We are particularly committed to translational research in areas of clear and unmet clinical need. We believe the funding sought in this call will have a tremendous impact on the direction of our future work. There are two aspects: The first is related to the translational potential and this will address the ability to deliver the directed differentiation protocol in GMP compliant cells. The second is a more basic science aspect - to understand the developmental processes governing endothelial cell production and interrogate and manipulate it further, with a particular emphasis on endothelial cell specification.
Benefit to the economy: A second major group of beneficiaries will be UK companies in the tissue regeneration space. The regenerative medicine landscape in Europe is dominated by SMEs and robust systems for generation of cells at clinical grade for trials will be of substantial interest in the cardiovascular field. Currently, most SC-derived cell therapies are autologous and used on an individual basis to treat relatively rare diseases. The work in this proposal will develop one of the earliest allogeneic pluripotent cell therapies and could also be the first entry into mass market disease. So a successful project would help change the emphasis on cell source and disease application; these steps address the transitional change required for pharma/larger company investment into the supply chain and wider uptake of cell therapies. If successful, the therapy would have a substantial impact on NHS burden in the UK.
The impact of this work will also have a substantial effect on the scientific community through publications and presentations. Our long standing interest and work in this area is now internationally recognised, through publication of our paper in ATVB and Stem Cells. The work of our laboratory also reaches the wider community and we have made presentations of this work and other cell therapy data at the British Society for Gene Therapy, which conducts an annual public awareness day for school children. In addition, Baker as member of the Gene Therapy Advisory Committee (GTAC), has given talks to school children as part of public engagement days organised by the UK Department of Health. Baker, as a member of GTAC, is well versed with the ethical aspects of human gene and cell therapy since GTAC is the ethics committee that governs all UK trials in this area. As vice chair he has long standing experience of GTAC and has undertaken additional training relating to UK ethical and regulatory considerations.
With respect to beneficiaries, we are very engaged with industry. We have a long standing and very productive collaboration with cell and gene therapy companies. This endothelial project will cement our new and exciting collaboration with Roslin Cells who specialise in GMP-grade production of embryonic stem cells and derivative products and has resulted in a highly productive TSB project that has just completed. We also hope to engage with other companies in the future and this is largely dependent on the success of our progress in this next stage of funding and the cell "potential" in the clinic.