Synthesis and Applications of Retinoids as Triggers of Stem Cell Differentiation (4)

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NESCI would be interested in funding / studentship opportunities for the following proposal.

NESCI are interested in industrial partners who may like to collaborate in one of these fields (for a CASE studentship or other awards), or in anyone who is interested in these areas of research (including other academic groups). For further details, please contact Helen Clamp from NESCI.

Project: Synthesis and Applications of Retinoids as Triggers of Stem Cell Differentiation (4)

Lead: Prof Todd B. Marder, Dr Andy Whiting, Dr Stefan Przyborski (NESCI), Dr Paul Hunt (Department of Biological and Biomedical Sciences, Durham University), Dr Chris Redfern (Northern Institute for Cancer Research, Newcastle University)


Retinoids are a class of natural and synthetic compounds which are structurally or functionally related to All-Trans Retinoic Acid (ATRA). ATRA, the oxidative metabolite of Vitamin A, has extensive biological activity, being critical to normal embryonic development and, for example, to the development of the nervous system. ATRA is also widely used to trigger stem cell differentiation. However, there are serious problems regarding reproducibility and homogeneity of cell types when this reagent is employed, especially due to the photoinstability of the compound under ordinary laboratory lighting, giving rise to numerous isomers which bind and activate one or more of 6 retinoic acid/retinoid X receptors (RAR ,; RXR ). In contrast, we have begun to develop synthetic retinoids which are photostable and which are both more active and more selective than ATRA in triggering stem cell differentiation, giving rise to homogeneous cell cultures. For example, one such compound provides neurons whereas an isomer of it provides epithelial plaques.

In addition, these two compounds perform completely differently when applied to chick limbs during early development using polymer bead technologies. The first predominantly causes the expected limb bud duplications with more activity than ATRA, whereas the latter compound results predominantly in nasal collapse with little evidence for an effect on the limb buds in which the bead is implanted. ATRA causes both outcomes at high frequency.

Finally, given the use of ATRA in treatment of neuroblastoma, and its inherent toxicity, we are investigating the activity (especially with regard to apoptosis) of our synthetic retinoids in neuroblastoma cells.

With northeast regional SME partner High Force Research Ltd. we have developed methodology to scale up our synthesis of these two compounds which are being commercialised by Reinnervate Ltd., a Durham University spin-out specializing in enabling stem cell technologies to whom our patent has been assigned. We work closely with both SMEs, and both are currently funding our work via EPSRC and BBSRC Industrial CASE Studentships. Thus, we have formed a very successful and productive collaborative team including 2 synthetic chemists, 2 biologists, 1 cancer researcher, and 2 local SMEs. We have filed one patent and published 3 papers to date with several more manuscripts being prepared for publication and a second patent being considered. All PhD students have been jointly supervised by at least 2 team members, and have included full time chemists, full time biologists and those who have carried out research in both chemical and biological aspects of the project.

In order to expand our efforts, both in terms of commercially valuable small molecule reagents for stem cell differentiation, as well as fundamental scientific studies of their mechanism of action and development of well-defined structure-activity relationships, we require additional Ph.D. students working with our team in the following areas:
Synthetic chemistry: we require additional synthetic chemists to prepare and characterise additional known as well as novel retinoids, especially those which are expected to bind/activate individual receptors with high selectivity. This is also required in order to probe SAR. The student will utilise novel synthetic routes including proprietary catalytic technologies developed to convert inexpensive hydrocarbons into such high value added retinoids. The student will also have the benefit of our close connections with High Force Research Ltd. through which practical aspects of industrial scale up can be explored.
Metabolism studies: At present, we do not have any information on the metabolism of our synthetic retinoids. There is scarce data available on this aspect of the work although many such compounds are known. However, there is no doubt that both activity and toxicity are related to the rate of metabolism of the compounds, and both are important issues, the latter being especially important to potential clinical applications ranging from neuroblastoma chemotherapy to regenerative medicine. Our proteomics data suggests the possibility that the high activity of some of our compounds may be related to their lack of metabolic pathways.

Binding assays to the 6 retinoid receptors: Critical to our SAR studies is the establishment of both binding constants and agonist/antagonist behaviour of each of the synthetic retinoids. There are scattered reports in the literature using different tests of activity and binding, but no consistent set of data is available at present.
Investigation into the biological activity of small molecules on stem cell differentiation. A major component of this initiative is to establish the biological mode of action of small molecules created by the chemistry team, with specific interest in the ability to direct the differentiation of stem cells in a robust and reproducible manner. For example, a specific project would be based around a cohort of compounds, to investigate the molecular mechanisms by which they influence cell behaviour and the characterization of the differentiation process. Information from such experiments will provide feedback to the chemists to enhance compound design and development. The student(s) would join a postdoc to receive daily supervision and training in molecular and cellular biology, cell culture and imaging will be provided. Thorough biological evaluation of compounds is currently a bottleneck in our research programme, given the complexity of the differentiation model, time taken to investigate mechanism of action, characterisation of the differentiation response and lack of an efficient assay for rapid parallel screening of compounds.

Biological screening of effects in vivo. An initial in vivo assay which allows sensitive quantitative comparison of the effects of different compounds is the implantation of polymer beads into chick limb buds, causing alterations to the number and type of digits formed. In addition to their effects on limbs, retinoids are well known to affect a number of other aspects of embryonic development such as establishment of the dorsal ventral axis of the eye, cardiac outflow tract septation, facial process outgrowth and neural tube closure. Further investigation of the biological properties of synthetic compounds is likely to identify further examples of specificity in biological effects. This work may also link to the metabolism studies described under project 2. This would involve working alongside an existing ASGBI PhD student supervised by PNH and SAP on a project to investigate the regulatory targets of the two compounds mentioned in the introduction in chick embryos.


It is expected that aspects (2) and (3) could be performed by a single PhD student, who would be expected to assist in the development of new assays for rapid screening. Aspects (4) and (5) are significant projects in their own right and each requires a separate student.

Thus, our proposal is for a total of 4 PhD students with current priority order being:
PhD student 1: Aspect 4
PhD Student 2: Aspects 2&3
PhD Student 3: Aspect 5
PhD Student 4: Aspect 1