STEM CELL GENETICS LAB
GROUP LEADER:
DR IVANA BARBARIC
My lab is located in the Centre for Stem Cell Biology at the University of Sheffield. The main focus of our research is the biology of pluripotent stem cells and their applications in regenerative medicine and disease modelling.
CONTACT DETAILS
Centre for Stem Cell Biology,
School of Biological Sciences
The University of Sheffield
Alfred Denny Building,
Sheffield, S10 2TN,
United Kingdom
LAB MEMBERS
DR DYLAN STAVISH
Postdoctoral Researcher
An issue in the translation of in vitro human pluripotent stem cells (hPSC) into clinically viable treatments has been their genetic stability in culture. Unfortunately, during prolonged cell culture, hPSC can acquire genetic changes, these changes however are not entirely random and some are commonly seen. These recurrent changes rise to prevalence by having a selective advantage over their wildtype counter parts and some share similarities with those seen in embryonal carcinomas, highlighting the danger in their possible therapeutic use. However, these genetic variants and their implications on stem cell characteristics have yet to be fully investigated.
I have been a part of the CSCB family for many years now allowing me to build up a strong knowledge base of pluripotent stem cell characteristics. My current work focuses on the implications of genetic variants on these characteristics. Using RNA-sequencing, timelapse microscopy, apoptotic priming and other techniques we can assess the effect of certain common genetic changes on stem cell behaviour allowing us to link certain phenotypes to particular genetic changes, perhaps highlighting driver genes. I am also interested in where the selective advantage of these cells arises and how the media and matrix combination in which we grow cells can impact not only their selective advantage but possible also the initial mutation occurrence. I hope my work can help in the optimisation of safer culture conditions of hPSC for regenerative medicine.
DR CHRISTOPHER PRICE
Postdoctoral Researcher
The observation that hPSCs may acquire non-random genetic changes during prolonged culture is a major concern for their use in regenerative medicine and disease modelling. The predominant genetic changes observed in hPSCs include gains of whole or parts of chromosomes 1,12, 17 and 20. Genetically variant cells possess a selective advantage over normal hPSCs that drives their ability to overtake normal cells and become the predominant cell within the culture.
My research aims to understand the mechanisms of selection that exist within hPSC cultures. Currently, I am investigating the selection mechanisms that are dependent upon the physical interaction of genetically normal and variant hPSCs. A greater understanding of the selection mechanisms used by variant hPSCs will provide a platform to design strategies that minimise the appearance of genetically variant cells.
CHIARA SANDER
Research Assistant
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THEODORE WING
PhD Student
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OWEN LAING
PhD student
Over prolonged culture, hPSCs are prone to acquiring recurrent genetic changes. Classically these have been observed as gross karyotypic abnormalities(Baker et al., 2007; Draper et al., 2004). More recently however, gains of point mutations in common oncogenes have been reported at a comparable rate (Avior, Eggan, & Benvenisty, 2019; Merkle et al., 2017). These changes pose concerns for the safe therapeutic use of hPSCS in regenerative medicine. For these variants to rise to prevalence in culture, mutation must occur, the basis of which is genome damage.
My research aims to explore the unique characteristics of hPSC metabolism and cell cycle as well as the conditions under which they are cultured to try to elucidate the specific molecular mechanisms underlying their genome damage. A better understanding of the genomic insults faced by hPSCs will inform improved culture conditions to ameliorate the perceived genomic instability of these cells.
BETHANY JAMES
PhD student
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LYDIA JESTICE
PhD student
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GABRIELE GELEZAUSKAITE
PhD student
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RESEARCH
Stem Cell Genetics Lab, Dr Ivana Barbaric
GENETIC CHANGES IN STEM CELLS
DISEASE MODELLING USING STEM CELLS
STEM CELL FATE CONTROL
SELECTED RECENT PUBLICATIONS
For a full list see: https://www.ncbi.nlm.nih.gov/pubmed/?term=barbaric+i
HDAC6 INHIBITION PARTIALLY ALLEVIATES MITOCHONDRIAL TRAFFICKING DEFECTS AND RESTORES MOTOR FUNCTION IN HUMAN MOTOR NEURON AND ZEBRAFISH MODELS OF CHARCOT-MARIE-TOOTH DISEASE TYPE 2A
Charcot Marie Tooth Disease (CMT) is a group of inherited progressive conditions affecting distal motor and sensory neurons, leading to muscle weakness, pain and loss of sensation in limbs. There are currently no treatments for this debilitating disease. To investigate disease mechanisms and facilitate treatment discovery, here we developed an in vitro model for CMT type 2A by introducing the patient-specific MFN2R94Q mutation into human embryonic stem cells (hESCs). Isogenic mutant and wild-type hESCs differentiated to spinal motor neurons with similar efficiency and gave rise to functional motor neurons in vitro. However, MFN2R94Q/+ spinal motor neurons displayed impaired mitochondrial trafficking, resulting in reduced numbers of mitochondria in distal parts of axons. Importantly, we showed that mitochondrial trafficking defects can be alleviated by treatment with an HDAC6 inhibitor. Chemical and genetic inhibition of HDAC6 also significantly rescued the motor phenotype in a zebrafish CMT2A model. Taken together, our study reveals a mutation-specific insight into CMT2A disease mechanism and confirms HDAC6 as a promising target for further therapeutic development.
GENETICALLY VARIANT HUMAN PLURIPOTENT STEM CELLS SELECTIVELY ELIMINATE WILD-TYPE COUNTERPARTS THROUGH YAP-MEDIATED CELL COMPETITION
The appearance of genetic changes in human pluripotent stem cells (hPSCs) presents a concern for their use in research and regenerative medicine. Variant hPSCs that harbor recurrent culture-acquired aneuploidies display growth advantages over wild-type diploid cells, but the mechanisms that yield a drift from predominantly wild-type to variant cell populations remain poorly understood. Here, we show that the dominance of variant clones in mosaic cultures is enhanced through competitive interactions that result in the elimination of wild-type cells. This elimination occurs through corralling and mechanical compression by faster-growing variants, causing a redistribution of F-actin and sequestration of yes-associated protein (YAP) in the cytoplasm that induces apoptosis in wild-type cells. YAP overexpression or promotion of YAP nuclear localization in wild-type cells alleviates their "loser" phenotype. Our results demonstrate that hPSC fate is coupled to mechanical cues imposed by neighboring cells and reveal that hijacking this mechanism allows variants to achieve clonal dominance in cultures.
doi: 10.1016/j.devcel.2021.07.019
The changes that drive differentiation facilitate the emergence of abnormal cells that need to be removed before they contribute to further development or the germline. Consequently, in mice in the lead-up to gastrulation, ∼35% of embryonic cells are eliminated. This elimination is caused by hypersensitivity to apoptosis, but how it is regulated is poorly understood. Here, we show that upon exit of naive pluripotency, mouse embryonic stem cells lower their mitochondrial apoptotic threshold, and this increases their sensitivity to cell death. We demonstrate that this enhanced apoptotic response is induced by a decrease in mitochondrial fission due to a reduction in the activity of dynamin-related protein 1 (DRP1). Furthermore, we show that in naive pluripotent cells, DRP1 prevents apoptosis by promoting mitophagy. In contrast, during differentiation, reduced mitophagy levels facilitate apoptosis. Together, these results indicate that during early mammalian development, DRP1 regulation of mitophagy determines the apoptotic response.
DOI: 10.1016/j.devcel.2022.04.020
OUTREACH
We are passionate about our research and value the opportunities to communicate our research findings and progress to the wider community. We are particularly dedicated to inspiring the next generation of scientists.
NEW STUDENT JOINS THE LAB
BRITISH SCIENCE WEEK
SOAPBOX SCIENCE EVENT
Nina's Outreach Video: Extracting DNA from strawberries
For budding scientists and their teachers/ parents/ carers: have a go at extracting the DNA in your home- or school-based lab following the instructions in this video.