Taking an interdisciplinary approach with a base in stem cell biology, bioengineering and biophysics, I am working to better understand how mechanical forces are sensed and integrated by pluripotent stem cells. While for many years stem cell scientists have focused heavily on identifying the chemical cues and genetic circuitry which govern pluripotency (the remarkable capacity to give rise to all somatic cell lineages), very little has been done to investigate the influence of the mechanical microenvironment. Since joining the Wellcome Trust/Medical Research Council Cambridge Stem Cell Institute in October 2013, I have been developing new hydrogel-based cell culture substrates capable of maintaining and reinforcing the pluripotency network in mammalian pluripotent stem cells. The hydrogel technology I am using permits tight control over the physical properties of the local environment in which pluripotent stem cells are cultured. Using recent genome engineering strategies such as CRISPR-CAS9 (Clustered Regularly Interspaced Short Palidromic Repeats) and other transgenic approaches, I am interrogating the necessity for individual, mechanically regulated, signalling pathway members in maintaining stem cell immaturity. To complement my use of hydrogels to alter the Young’s modulus (stiffness) of the substrate, I also employ biophysical techniques such as Atomic Force Microscopy (AFM), to measure cellular elasticity, and Traction Force Microscopy (TFM) for the measurement of cell-generated traction stresses. Novel nanoindentation approaches will help determine the precise mechanical properties which lead to the pluripotency promoting effects of the hydrogel substrates. Collectively, this information will be used to pinpoint material properties, cellular elasticises and cell-driven forces which control the cell state transitions of stem cells.
Another aspect of my research focuses on indentifying the biophysical and molecular mechanisms underpinning cellular reprogramming. The pioneering discovery that differentiated cells of the adult can be ‘reprogrammed’ into pluripotent stem cells was awarded the Nobel Prize in Physiology or Medicine in 2012. The aptly named Induced Pluripotent Stem Cells (or iPS cells) created by the reprogramming process hold tremendous promise for regenerative medicine and disease modelling. However, current reprogramming protocols typically take weeks and the efficiency is extremely low (<1%). The distinct alterations in cellular architecture which accompany this molecular rejuvenation implicate a role for force-based phenomena. Using the hydrogel substrates I have created, in combination with select small molecule inhibitors and transgenic approaches, I am investigating the potential for exploiting novel mechno-chemcial synergies to promote the profound genetic rewiring necessary for reaching the reprogrammed ‘ground’ state.
Developing biomimetic matrices for enhanced cellular reprogramming (Funded by the Medical Research Council: MR/M011089/1)
Uncovering mechanisms underlying the transdifferentiation of human muscle fibroblasts into adipocytes (Funded by the BBSRC: BB/L009943/1)
Satellite cells are the resident stem cell population in adult skeletal muscle and are so named because of their distinct anatomical location on the periphery of the mature myofibres. Although these satellite stem cells are excellent at regenerating damaged muscle, for many years it was believed that in disease conditions and in normal aged muscle, these cells could also differentiate into non-muscle cell types. This purported non-myogenic differentiation is disease states would ostensibly explain the excess connective tissues (fibrosis) and adipose (fat) tissue infiltration seen in these conditions. During my PhD I demonstrated that in humans, satellite cells are committed myogenic precursors that do not alter their lineage even when challenged to do so. Although satellite cell derived myogenic cells were able to express transcription factors typically associated with non-myogenic cells they could still be differentiated into large multinucleated muscle fibres in vitro. In contrast, via detailed molecular screening I demonstrated that stromal fibroblasts which are ubiquitous in skeletal muscle were at least t least bipotent in their cell fate options and could give rise to both fat and connective tissue. This means that as opposed to the satellite cells, it is the muscle fibroblasts which are the likely source of fibrosis and fatty degeneration typical of many muscle diseases such as Duchenne Muscular Dystrophy. These cells are an ideal therapeutic target for myopathic diseases and age related muscle wasting (sarcopenia) and ongoing work in collaboration with King’s College London and a major pharmaceutical corporation seeks to identify the molecular players and druggable targets involved in this process.
- Stem Cell Biology, Biophysics and Bioengineering
- PhD - King’s College London, UK. Physiology (2009-2013). Thesis title: ‘Adult human primary skeletal muscle stem and progenitor cells: Assessment of cell fate and the role of canonical Wnt-Beta-catenin signalling’. Supervised by: Professor Stephen Harridge & Professor Phillipa Francis-West.
- MSc - Human and Applied Physiology - Distinction (Graduated no. 1 in class). King’s College London, UK (2008-2009).
- 2013 - King’s College London: Tadion Rideal Prize for Molecular Science. Awarded to the best molecular science related PhD thesis across the College in 2013 (https://blogs.kcl.ac.uk/kclgradschool/2014/10/08/tadion-rideal-prize-win...).
- 2009 - Colt Foundation Prize for: ‘Best Human and Applied Physiology MSc Project’.
- 2008 - University Prize for: ‘Best Undergraduate Dissertation’.
- British Society of Cell Biology – Full member (2013-present)
- Physiological Society – Full member (2008-present)
- Agley C. C.et al. (2017). Active GSK3β and an intact β-catenin TCF complex are essential for the differentiation of human myogenic progenitor cells. Scientific Reports 7, Article number: 13189.
- Agley C. C.et al. (2014). Isolation and quantitative immunocytochemical characterization of primary myogenic cells and fibroblasts from human skeletal muscle. JoVE, e52049.
- Agley C. C.et al. (2013). Human skeletal muscle fibroblasts, but not myogenic cells, readily undergo adipogenic differentiation. J Cell Science, 126, 5610-5625. [Selected as an ‘Article of Interest’ in January issue of Development (2014, 141: e206)]
- Agley C.C. et al. (2012). An image analysis method for the precise selection and quantitation of fluorescently labelled cellular constituents: Application to the measurement of human muscle cells in culture. Journal of Histochemistry and Cytochemistry 60 (6), 428-438.[Recipient of JHC June Editor Choice Article of the Month]
- Alsharidah M., Lazarus N.R., George T.E., Agley C. C., Velloso C. P. & Harridge S.D.R. (2012). Primary human muscle precursor cells obtained from young and old donors produce similar proliferative, differentiation and senescent profiles in culture. Aging Cell 12 (3), 333-344.
- Thakur M., Crow M., Burden N., Davey G., Levine E., Agley C. C., Denk F., Harridge S. and McMahon S. (2014). Defining the nociceptor transcriptome. Front. Mol. Neurosci. Front. Mol. Neurosci. 7:87. doi: 10.3389/fnmol.2014.00087
- Puthucheary Z.A.,Rawal J., McPhail M.,Connolly B., Ratnayake G., Chan P., Hopkinson N., Padhke R., Dew T., Sidhu P.S., Velloso C., Seymour J., Agley C.C., Selby A., Limb M., Edwards L.,Smith K., Rowlerson A.,Rennie M.J., Moxham J.& Harridge S.D.R., Hart N., Montgomery H.E. (2013). Acute skeletal muscle wasting in critical illness. JAMA, 310 (15):1591-1600.