Immunogenicity test platform - in vitro and in vivo

Regenerative medicine is a branch of medicine that aims to replace damaged or diseased tissue, thereby treating and potentially curing illnesses that are currently untreatable. Two different regenerative medicine approaches are currently being investigated: the first is to stimulate the body's own cells to repair the tissue; the second is to transplant new cells into the body.

This research proposal focuses on the second approach, and in particular on the therapeutic potential of pluripotent stem cells. Pluripotent stem cells (or PSCs for short) are "master cells" capable of becoming any cell or tissue. They are also able to self-renew, meaning that they have the ability to produce endless copies of themselves. PSCs come in two types - embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). ESCs come from very early preimplantation embryos, whereas iPSCs are made by forcing adult cells back into a pluripotent state by using fairly recently developed technology known as cell reprogramming. Just like ESCs, iPSCs can expand indefinitely and can be used to make any tissue.

Although there has been a huge amount of progress in making different types of human tissue from ESCs and iPSCs there are still lots of unanswered questions. In particular it is not known if cell and tissue products derived from ESCs and iPSCs will be rejected by the patient's immune system, in the same way that solid organs (like kidney and liver) are rejected if the recipient and donor are not "well matched". Our research aims to help address that question. Through a combination of laboratory experiments and animal (mouse) studies we will determine whether or not two cell products (ESC derived nerve cells and iPSC-derived liver cells) are capable of activating the human immune system. We have chosen these particular cell products as both are about to be tested in clinical trials involving patients with Parkinson's disease and liver failure.

We believe that this study is important. As well as providing information on two specific clinical products - our project aims to establish a generic protocol for testing future cellular therapies and in doing so has the potential to significantly advance the field of regenerative cellular therapy.

We will work up this platform by studying the immunogenicity of two allogenic cell products - ES-derived dopaminergic cells and iPSC derived hepatocytes, chosen because they are about to enter clinical trials in Parkinson's disease and liver failure respectively.

Our proposal will involve the following work packages:

1. We will characterise the expression of innate and adaptive immune molecules by our cell products at different stages of development, and in the presence of inflammatory mediators, using PCR and flow cytometry.
2. We will define the immune response of allogeneic T cells to our cell products in mixed lymphocyte reactions and via autologous DC presentation.
3. For ES-derived dopaminergic cells we will study the effect of immunosuppressive drugs on the ability of day 16 ES-dopaminergic progenitor cells (the stage at which they are transplanted), to fully differentiate into mature dopaminergic neurons both in vitro and in vivo.
4. We will investigate the immunogenicity of iPS-derived immunogenicity using "state-of-the-art" 3D "liver on a chip" cultures.
5. We will perform in vivo studies of our cell products after transplantation in immunodeficient mice reconstituted with a human immune system, studying the host immune response using droplet based, single cell V(D)J and expression profiling (10X) of CD45+ human immune cells extracted from the transplanted tissue, draining lymph-nodes and, for comparison, blood.
6. Reverse translation - finally, we will harvest and store peripheral blood (and where relevant) CSF derived mononuclear cells, and serum, from individuals undergoing transplantation with our products in our clinical centres, with the aim of determining whether or not any unique cell/transcriptomic signatures present in our mouse models can be identified in the patient derived samples, and whether or not these signatures relate to graft rejection and or clinical outcome.

Beneficiaries:
The immediate beneficiaries will be the PIs, collaborators, and all investigators associated with the UK Regenerative Medicine Platform. However the benefit of this work will be far reaching extending to the stem cell biology, transplant, immunology and cancer research communities in the UK and internationally. Clinicians involved in organ transplantation and regenerative medicine therapies will also be beneficiaries. The commercial sector, members of the lay public, both healthy individuals and patients, will benefit. UK government agencies, including policy makers, the Technology Strategy Board (TSB), MRC and regulatory agencies, such as the MHRA, will benefit. The benefits will not be restricted to the UK but will have an impact globally.

How will they benefit?
1. Academics will benefit by increased knowledge of how the immune system recognizes and responds to cellular products. This knowledge will enable us to understand if and how the immune system should be modulated to improve the clinical efficacy of these products.
2. Patients will benefit by improved treatments for a variety of diseases that currently lack optimal treatments, including liver failure and Parkinson's disease. Healthy individuals will benefit by improved quality of life in old age, increased understanding of research, and increased willingness to participate in clinical trials.
3. The commercial sector will benefit by having new knowledge on which to develop new therapeutics, new possibilities for partnering with academics.
4. The UK government will benefit by generation of intellectual property, leverage of ongoing MRC investment in the Centre for Transplantation, commercialization of products arising from the research, reduced health care costs and by involvement in the work force of people who would otherwise be unable to work through ill health. The reduced burden to the National Health Service will allow resources to be channeled into other areas, such as acute care. The stature of the UK internationally will increase, because the research carried out will impact on the global field of regenerative medicine.