Improving the efficiency of human somatic cell nuclear transfer

Embryonic stem cells (ESCs) have the potential to repair damaged tissues and organs and present a potential cure for many grave diseases. However, as with organ transplants, transplantation of cells derived from ESCs can invoke an immune response that may lead to rejection. This problem could be overcome by creating ESCs from other cell types, such as a skin cell, by reversing the genetic changes that give a skin cell its characteristic features. This process, which is called nuclear reprogramming, can be achieved by transplanting the skin cell nucleus into an egg from which the genetic material has been removed. An artificial stimulus is then required to initiate embryonic development leading to the production of ESCs.

The main aim of this project is to optimise the stimulus required to initiate embryonic development. We use mouse and human eggs for this purpose. However, research progress has been hampered by the scarcity of good quality human eggs. We therefore aim to increase the availability of human eggs by offering IVF patients the opportunity to donate eggs to this research, in return for a contribution towards the cost of their treatment.  The project will advance progress in techniques for producing patient-specific ESC.

Therapeutic cloning offers the prospect of cell-based therapies without the risk of immune rejection. The success of therapeutic cloning depends on the development of reproducible methods for generating human embryonic stem cells (hES cells) from embryos produced by transplanting a nucleus of an adult somatic cells into an oocyte. The overall aim of this project is to increase the efficiency of nuclear transfer (NT) in human oocytes. A major obstacle is the scarcity of freshly harvested human oocytes. Altruistic donation is rare and carries the risk ovarian hyperstimulation syndrome. To overcome this we propose to introduce an ?egg sharing? scheme in which selected women undergoing ovarian stimulation for fertility treatment donate half of their oocytes in return for a reduction in the price of treatment. This scheme has been approved by the HFEA and has been well received by patients. The main scientific areas of focus are: 1) Egg activation: we will test the efficacy of the sperm-specific protein phospholipase C ? (PLC?), and a constitutively active form of its primary molecular target, calmodulin-dependent kinaseII (CamKII), in promoting development of NT blastocysts. 2) Enucleation: we will test the hypothesis that removal of the meiotic spindle compromises the development of NT embryos. 3) Reprogramming: we will perform experiments in mouse and human oocytes to compare the efficiency of Oct4 demethylation and transcription in oocytes at different stages of maturation. The project brings together a unique combination of skills and experience in ethics and regulation of gamete/embryo donation; primate NT and ES cell derivation, cell biology of the oocyte, and the molecular mechanisms of epigenetic modification. Our combined expertise puts us in a strong position (i) to maximise the translational potential of NT for the treatment of disease (ii) to gain insights into the mechanisms by which the oocyte modulates the cell cycle and epigenetic regulation of the somatic cell genome.