LMP student seminars: 25 November
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.
3. Cardiovascular, Physiology and Metabolism
Location: MSB 4171
Manami Kondo
- Title: Enhancing Hepatocyte Maturation In Vitro via 3D Co-Culture with IPSC-Derived Hepatic Stellate Cells
- Supervisor: Dr. Shinichiro Ogawa
Shiyuan Bian
- Title: The effect of cyclical stretch on the lung: Implications for lung re-epithelialization
- Supervisor: Dr. Golnaz Karoubi
5. Infectious Diseases, Inflammation and Immunology
Location: MSB 4279
Kleio Chatanaka
- Title: Use of plasma biomarkers for management of patients with diffuse glioma
- Supervisor: Dr. Eleftherios P. Diamandis
Manus Yu
- Title: The role of the HIV-1 membrane fusion protein gp41 in immunosuppression
- Supervisor: Dr. Jeffrey Lee
Abstracts
Manami Kondo: TBA
Chronic liver disease presents a major health challenge in Canada, with demand for liver transplants far exceeding available donors. Liver tissue engineering offers a promising solution by utilizing non-parenchymal cells, such as hepatic stellate cells (HSCs) and liver sinusoidal endothelial cells (LSECs), crucial for maintaining liver function alongside hepatocytes. Current liver models lack physiological relevance due to the absence of liver-derived non-parenchymal cells. HSCs are essential for liver function and fibrosis, yet their origins and differentiation pathways are not fully understood. To address this, we developed a protocol to generate WT1-positive mesodermal progenitors—precursors to HSCs—from human pluripotent stem cells (hPSCs), achieving over 90% differentiation efficiency by modulating Wnt and retinoic acid signaling. These progenitors further matured into quiescent HSCs, suitable for constructing 3D organoids. Co-culturing HSCs with hepatoblasts enhanced hepatocyte maturation, indicated by increased expression of CYP3A4 and quiescence markers (PPARγ, SPARCL1), confirming that HSCs are critical for promoting hepatocyte function. Additionally, retinoid storage was confirmed, demonstrating the coculture’s ability to mimic in vivo processes. Without HSCs, hepatoblasts tended toward cholangiocyte differentiation, emphasizing the essential roles of HSCs in maintaining hepatocyte identity. Co-culturing hepatoblasts with mature HSCs sustained albumin secretion, while cellular plasticity of immature HSC progenitors compromised hepatocyte function, indicating that mature HSCs create a stable environment essential for hepatocyte maintenance. These findings highlight the potential of hPSC-derived HSCs to support hepatocyte maturation in our model. Future efforts will focus on integrating endothelial cells to create a comprehensive 3D liver model for regenerative medicine and transplantation.
Shiyuan Bian: The effect of cyclical stretch on the lung: Implications for lung re-epithelialization
Lung transplantation remains limited by donor organ scarcity. Bioengineered lungs, developed through re-epithelializing acellular scaffolds with universal cell lines, represent a promising alternative. However, current recellularization protocols often fail to replicate functional epithelium, neglecting the role of mechanical ventilation pre-recellularization. This study examines how cyclical stretch in bioengineered lung scaffolds impacts lung epithelial cells, aiming to enhance epithelial attachment, proliferation, and function.
To achieve this goal, a Negative Pressure Wet Ventilation System (NPWVS) was utilized with a decellularized/recellularized mouse lung model. Acellular scaffolds underwent various ventilation conditions: native, non-perfused/non-ventilated, perfused-only, and combinations with tidal volumes of 0.3mL and 1.5mL at 16/32 breaths per minute (BPM) for 5 days. Structural and mechanical changes were assessed via histology, tensile strength testing, and atomic force microscopy. Human lung epithelial cells (A549 and primary human ATII cells) were cultured on pre-conditioned scaffolds and evaluated through Precision Cut Lung Slices (PCLSs) over 1, 3, and 5 days and whole-lung recellularization for 5 days, analyzing cell viability, coverage, and proliferation.
Our results show that moderate ventilation conditions (0.3mL/16BPM) preserved scaffold structure and ECM protein composition, whereas excessive ventilation reduced scaffold stiffness, indicating damage. PCLSs from moderate ventilation exhibited improved A549 and ATII cell adhesion, viability, and proliferation. Pre-conditioning with moderate ventilation also enhanced epithelial cell coverage compared to perfusion-only methods in whole-lung recellularization.
In conclusion, moderate ventilation optimizes epithelial cell coverage on mouse lung scaffolds without significant structural compromise. Future studies will investigate its effects on human epithelial cells and associated mechano-transduction pathways.
Kleio Chatanaka: Use of plasma biomarkers for management of patients with diffuse glioma
Diffuse gliomas are aggressive malignant tumors, oftentimes with poor prognosis. There is an unmet need for the discovery of new, non-invasive biomarkers for the differential diagnosis, prognosis, and management of such brain tumors. We previously discovered several markers that could distinguish between malignant and benign brain tumors. For this project, our objective was to validate these plasma biomarkers and compare them with established brain tumor molecular markers and survival. In addition, we wanted to discover markers that could prognose and monitor patients with malignant brain tumors. Our cohort consisted of patients with benign and malignant brain tumors (validation cohort: Glioblastoma (GBM)= 77, Astrocytomas= 26, Oligodendrogliomas= 23, Secondary tumors= 35, Meningiomas= 70, Schwannomas= 15, Pituitary adenomas= 15, Normal individuals= 30; Longitudinal, discovery cohort: paired GBM= 6). For measurements, we performed analyses using MesoScale Diagnostics’s electrochemiluminescence S-plex immunoassays. Our results showed that high plasma GFAP concentration was associated with GBM, low GFAP/high FABP4 were associated with meningiomas, and low GFAP/low FABP4 were associated with astrocytomas and oligodendrogliomas. Several prognostic genetic alterations were significantly associated with plasma biomarker levels. NEFL and tTau significantly increased during GBM recurrence. We found an association between plasma tTau and MMP1 and overall survival of diffuse glioma patients. None of the candidate biomarkers could reliably discriminate GBM from primary or secondary CNS lymphomas and other secondary tumors. We can conclude that GFAP, NEFL, FABP4, MMP3, MMP1 and tTau are useful for differential diagnosis, prognosis and monitoring of patients and are associated with molecular changes in diffuse gliomas.
Manus Yu: The role of the HIV-1 membrane fusion protein gp41 in immunosuppression
Human immunodeficiency virus-1 (HIV-1), like many other retroviruses, has the capability of suppressing the immune system through its envelope proteins. HIV-1 has been shown to use its fusion protein gp41 to inhibit immune system activation against its viral particles. This is achieved through a conserved immunosuppressive region (ISR). Although previous studies have highlighted the immunosuppressive effects from synthetic peptides corresponding to the ISR, the mechanistic pathway and putative receptor have yet to be identified. Thus, we propose to use biochemical and structural approaches to elucidate the unidentified receptor, and we hypothesize that the ISR of HIV-1 gp41 will bind to surface receptor(s) on specific immune cells to enhance immunosuppressive cytokine production.
To accomplish this, trimeric recombinant gp41 and relevant controls (ISR scrambled and ISR deleted) were expressed and biophysically characterized. We found that gp41 bound to B cells, monocytes, and conventional dendritic cells and triggered cytokine release in human peripheral blood mononuclear cells. We also found that gp41 bound to a monocytic cell line (THP-1) and B-cell line (BJAB). Future experiments will use crosslinking mass spectroscopy analysis on gp41 bound to immune cells to identify candidate receptor(s) to investigate.
Because previous studies used synthetic peptides due to trimeric gp41 being hard to express and purify, this is the first study to characterize the immunosuppressive phenomenon of trimeric gp41 using structure-function studies. Identification of host cell receptors lays the groundwork for further research into signal transduction pathways involved, and it provides guidance into the development of effective HIV vaccines and antivirals to recover host immune system function.
Contact
No need to register.
Contact lmp.grad@utoronto.ca with any questions