LMP student seminars: 17 March
Each week during term time, MSc and PhD candidates in the Department of Laboratory Medicine and Pathobiology present their research.
Anyone is welcome. No need to register.
Location: Medical Sciences Building, rooms 4171 or 4279, see below.
As part of the core research curriculum, students taking LMP1001/2/3: Graduate Seminars in Laboratory Medicine and Pathobiology will present their projects. Please see abstracts below.
Group 2: Cancer, Development and Aging
Location: MSB 4171
Catherine Lin
- Title: Use of Magnetic Resonance-guided Focused Ultrasound in the Treatment of Diffuse Intrinsic Pontine Glioma
- Supervisor: Dr. James Rutka
Group 3: Cardiovascular, Physiology and Metabolism
Location: MSB 4279
Yuetong Song
- Title: Generation of mature lung alveolar epithelial cells from human induced pluripotent stem cells.
- Supervisor: Dr. Amy Wong
Kristen Schulz
- Title: Chronic knockout of the ETS transcription factor ERG promotes loss of endothelial cell identity and endothelial cell dysfunction in an aortic endothelial cell model relevant for atherosclerosis
- Supervisors: Dr. Kathryn Howe and Dr. Jason Fish
Abstracts
Catherine Lin: Use of Magnetic Resonance-guided Focused Ultrasound in the Treatment of Diffuse Intrinsic Pontine Glioma
Diffuse intrinsic pontine glioma (DIPG) is a brain tumour that occurs in the pons and is the leading cause of brain tumour-related deaths in childhood. The median age of diagnosis is 6.5 years, with a median overall survival of 11 months after diagnosis. Current treatment for DIPG is radiation with or without chemotherapy, given that surgical resection is impossible due to its location within the parenchyma of the brainstem, a critical structure responsible for regulating heart rate and breathing. A major obstacle to the treatment of DIPG is impaired drug delivery across an intact blood-brain barrier (BBB). However, magnetic resonance-guided focused ultrasound (MRgFUS), which combines focused ultrasonic waves with injected microbubbles, can transiently open the BBB without tissue damage and offers a solution to enhance the delivery of BBB-impermeable drugs. My lab has demonstrated doxorubicin delivery in DIPG mouse models using MRgFUS and is leading a Phase I/II clinical trial to evaluate this approach in patients. Additionally, immunomodulatory effects have been observed with MRgFUS. However, this has not yet been characterized in DIPG models. Recent studies have also shown that the tumour-immune microenvironment (TIME) of DIPG is rich in myeloid cells, contrary to previous findings. Further understanding of the immune effects of MRgFUS in DIPG may enhance the use of immunotherapy for this devastating disease. We hypothesize that using MRgFUS as a delivery method for immunotherapeutic agents, combined with its immunomodulatory effects, may enhance anti-tumour immune responses in DIPG and ultimately improve treatment outcomes for DIPG patients. Specifically, we aim to characterize MRgFUS-induced immune changes and evaluate the efficacy of immunotherapy agents delivered via MRgFUS in an immune-competent DIPG murine model. This study will allow us to evaluate drugs and immunotherapeutics with compromised efficacy in DIPG due to BBB impermeability, as well as facilitate immunotherapy treatments using a safe delivery system with MRgFUS. This proposal also considers and mobilizes a functional immune response, thus more precisely mirroring the clinical course of the disease. Altogether, we may be able to harness the patient’s own immune system for anti-tumour responses. Ultimately, we hope to improve the current therapeutics available to DIPG patients and their survival.
Yuetong Song: Generation of mature lung alveolar epithelial cells from human induced pluripotent stem cells
Gas exchange occur primarily in the distal regions of respiratory epithelium called alveolar sacs which are comprised of two types of alveolar epithelial cells type 1 (AT1) and type 2 (AT2). Bipotent alveolar progenitor cells (BAPC) are understood to be a source of AT1 and AT2 cells in the lungs and disruption to these alveolar cells are implicated in several lung diseases including respiratory distress syndrome and pulmonary emphysema. Generation of de novo mature alveolar cells from human pluripotent stem cells (hPSC) is an attractive and promising strategy for regeneration of the alveolar epithelium. However, establishing mature alveolar cells from directed differentiation protocols of iPSC remains a challenge. Here, we developed a directed differentiation protocol to generate expandable BAPCs from hPSCs and further show that these cells can form 3D “alveolospheres” consisting of immature/fetal AT1 and AT2-like cells. Moreover, we can induce further maturation under coculture with human fetal lung stromal cells and mechanical stimulation mimicking physiological forces of breathing. Evidence of cellular maturation includes production and secretion of surfactant proteins (for AT2 cells) and nuclear expression of Hippo pathway effector protein YAP (for AT1 cells). Overall, our study overcomes an important hurdle in directed differentiation protocols to generate mature and functional cell lineages and offers an opportunity to generate relevant cell types for distal lung regeneration using hPSC.
Kristen Schulz: Chronic knockout of the ETS transcription factor ERG promotes loss of endothelial cell identity and endothelial cell dysfunction in an aortic endothelial cell model relevant for atherosclerosis
Background: The ETS transcription factor ERG is a key endothelial cell (EC) transcription factor. ERG represses vascular inflammation and is downregulated in chronic inflammatory diseases (e.g. liver fibrogenesis, atherosclerosis). Previously, transient ERG knock-down has been associated with endothelial-mesenchymal transition (EndMT) and EC dysfunction; however, the mechanisms underlying EndMT and the EC dysfunction associated with chronic ERG loss have not been elucidated in an atherosclerosis-relevant model. We hypothesize that chronic ERG knockout (KO) in telomerase-immortalized human aortic ECs (teloHAECs) induces EndMT and contributes to EC dysfunction underlying vascular dysregulation in atherosclerosis.
Methods: TeloHAECs with CRIPSR/Cas9-mediated deletion of ERG were used. Chromatin accessibility and gene expression in ERG KO and wildtype (WT) teloHAECs were assessed using ATAC-seq (n=2) and RNA-seq (n=5-6). TOBIAS and diffTF were used to identify enriched motifs by footprinting (P<0.05) and to profile TF activity (FDR<0.05), respectively. ERG-mediated EC dysfunction was investigated using immunofluorescence (IF; n=3), western blot (WB; n=3), and a timelapse migration assay (n=3).
Results: There were ~ 21,000 differentially accessible chromatin peaks between ERG KO and WT ECs. Integrated analysis of chromatin accessibility and gene expression demonstrated increased activity of TGFβ-SMAD and IL-1β signaling constituents and classical EndMT transcription factors. Loss of ERG downregulated EC genes (e.g., CLDN5, TIE1) and protein expression (e.g., CDH5, vWF) and upregulated mesenchymal genes (e.g., ACTA2, FSP1) and protein distribution (e.g., FN1, COL1A1). Investigation of EC-dysfunction phenotypes revealed increased migration and proliferation in ERG KO teloHAEC - with the percentage of Ki67 positive ECs increasing from 14% to 49% (P<0.05, n=3).
Conclusion: ERG KO in cultured aortic ECs markedly impacts chromatin accessibility and gene expression and induces EC identity loss, migration, and proliferation, providing mechanistic insight into the role of ERG in vascular dysfunction in atherosclerosis.
Contact
No need to register.
Contact lmp.grad@utoronto.ca with any questions.