Functional Priming of Human Cord Blood Derived Haematopoietic Stem and Progenitor Cells

Pioneered more than half a century ago blood transplants are now routinely conducted at many hospitals in the UK and abroad. The cells that make transplant work are blood stem cells. There is till much we don't know about blood stem cells which are very rare (only 1 in a 100,000 cells in the bone marrow is a stem cell) and importantly we can't grow them effectively in a dish. If we could we would have an endless supply of cells for transplants and could learn more about them such as how they grow and divide and how they turn in to the red blood cells that carry oxygen to our tissues, the platelets that make clots when we get wounded, and the white cells that fight infection in our bodies. Our project is aimed at trying to make the stem cells derived from cord blood, taken when other give birth, more efficient so that they make better transplants. This would increase the numb prof patients that could benefit from transplant and may make transplants cheaper and more efficient. We have found a gene that we thinks can help with this and so we plan to test its activities and work out how it makes stem cell functions better, we think it activates them and puts them in a heightened state of activity - sort of a 'red alert'. It probably does this by recruiting other genes - i.e. building a network that together controls stem cells. These kinds of networks or genetic circuits are important in all aspect soft cell g-fucntion an human development so understanding hewn works should could broader insight in general principles at play and may be useful in other kinds of stem cells.

Stem cells are important in normal development, for tissue homeostasis and for regenerative medicine. Understanding the regulation of cell fate in stem and progenitor compartments would lend insight into stem cell physiology and its pathology in diseases such as cancer. Despite the extensive analysis of Haematopoiesis as a paradigm for somatic stem cells, blood stem cells cannot routinely be expanded ex vivo. This limits study of their cell fate control mechanisms but also constrains the use of cord blood units in clinical transplant settings. We have shown that Nov/ CCN3 may enhance the functional capacity of CB stem cells and we propose to evaluate its impact on a number of engraftment parameters in a xenograft model to establish and optimise it potential as a therapeutic. We will also dissect its mechanism of action with a view to establishing genes and pathway that may further enhance stem cell potential but also to understand how Nov effects what we hypothesise to be a more global change in cellular state akin, at least conceptually, to the Naive to Primed transition reported for pluripotent stem cells.

Haematopoietic transplantation has been at the forefront of regenerative medicine for more than half a century and blood stem cells have been a paradigm for stem cell biology for almost as long. Despite the life-saving potential of this treatment, there is scope for considerable improvement with a concomitant impact on patients. Pioneered by Gluckman and Broxmeyer, cord blood transplants have had a dramatic impact but the size of units often prohibits their wider use in adults. For example, the Anthony Nolan Trust aims to bank some 15,000 cord blood units but will need to collect some 70,000 to 100,000 units since only 15-20% of these will be clinically useful. Our approach of ex vivo priming of CB stem cells could alter this picture and consequently have large impact on cord blood banks and eliminate the effort, labour, and cost associated with collection of ultimately unsuitable units. Currently the Anthony Nolan (as just one Cord Blood banking Activity) seeks to identify 1400 HSC grafts per annum and since only 50% of grafts are successful, improvement of engraftment in respect of kinetics and lineage composition could be very beneficial. Most importantly, being able to use a single as opposed to double units would represent a major advance and potential economic saving. There is a reasonable probability that significant data will arise from our quantitative assessments of stem cell potential in vitro and in vivo that could lead to an early translation to clinical trial. This would be a significant impact in its own right and we have already discussed the possibilities with the Chief Investigator of the previous National cord Blood Trials in the UK. Samples arising from such a trial would provide an additional resource for reverse translation and further discovery biology. The translational potential of our work would attract interest from local cell therapy centres (CCGTT-UCL) and may may ultimately provide a project for the Cell Therapy Accelerator as well as attracting involvement of regulators and health economists. Nov itself or molecular effectors of its activities are likely to attract commercial interest as potential therapeutics. In view of potential future translation we will, if funded, seek to design some of our early experiments (see aim 1) with view to later GMP conversion with the assistance of Mark Lowdell (see letter of collaboration). Our mechanistic studies should also reveal aspects of fundamental stem cell biology that will be of general interest and may provide further clues to enhance CB stem cell activity. More generally they will add to the emerging conversation around cell state transitions in stem cells that have resonance in pluipotent settings which are a major engine for more general regenerative medicine activities.