Martin Post

Degrees: Ph.D

Affiliations: Institute for Medical Sciences, University of Toronto

Courses Taught: PSL 1067H, PSL 1069H (coordinator)

Research Synopsis

Research Interests: The aim of my research is to understand the fundamental biological and physiological mechanisms that direct lung development and the impact of preterm birth on this process. The long term objective is to use the information to develop new therapeutic strategies, including lung regeneration, or to improve existing therapies

Keywords: Developmental lung biology, Lung lipid and protein biochemistry, Lung mechanobiology, Ventilation induced lung injury, Asthma and COPD (chronic lung disease), Lung regeneration (stem cells, tissue engineering etc), Placental development and disease, Biomarker development

Detailed Description: Preterm birth occurs in 5-10% of all pregnancies, leading to 75% of the early (neonatal) mortality and long-term disability (including cerebral palsy, deafness, blindness, mental and respiratory problems).  One major complication associated with preterm birth is immaturity of the lung and, despite modern management, such as the use of surfactant and newer modes of neonatal ventilation; pulmonary immaturity remains a leading cause of neonatal morbidity and mortality.  The aim of my research is to understand the fundamental biological and physiological mechanisms that direct lung development and the impact of preterm birth on this process. The long term objective is to use the information to develop new therapeutic strategies, including lung regeneration, or to improve existing therapies.  Below see overview of my research areas:

1) Lung morphogenesis results from multiple interacting signaling pathways. Although great strides have been made in elucidating some of the signaling pathways that contribute to lung development there remain many gaps in our knowledge. My long-term goal is to integrate the identified signaling pathways in a morphogenetic map, which can then be used to model aberrant lung development.

2) Mechanical ventilation is commonly used in neonatal respiratory failure, and is well known to cause -or worsen lung injury. In the neonate, developing lungs are still forming distal air exchange units: thus, mechanical ventilation can impair alveolar development by inhibiting lung cell growth, augmenting cell death and increasing inflammatory mediator expression. We investigate the impact of ventilation (stretch) on lung cell fate in vitro and in vivo.

3) Emerging evidence suggests that stem cells can differentiate into lung cells. However, the environment and factors that are required for the differentiation of stem cells into lung-specific cells are largely unknown. We are investigating the cellular commitment to a pulmonary phenotype and the potential of acellular lung scaffolds for tissue engineering. A new exciting direction we explore is stem cell-based innate immune therapy using stem cell derived alveolar macrophages in pneumonia models. 

4) Sphingolipids are involved in the regulation of many cellular processes. Ceramides trigger cell death while sphingosine-1-phosphate (S1P) promotes cell survival. Thus, ceramides and S1P form a rheostat that balances apoptosis and proliferation; processes gone awry in the ventilated preterm lung. Understanding and manipulation of the ceramide-S1P axis in the injured newborn lung may benefit its repair. We are investigating sphingolipid metabolism in ventilated newborn animals and hyperoxia models of neonatal lung disease (i.e. BPD).

5) Another line of investigation concerns lipidomics (large scale study of lipid quantity and function which may provide a molecular signature to a certain pathway or a disease condition). We perform lipidomic analysis to identify potential molecular lipid signatures in the tracheal fluid or sputum of (BPD, Asthma, COPD) patients as predictors and prognostic markers for outcomes. We focus on wide screens for eicosanoids, sphingolipids (ceramides, sphingosines etc), phospholipids and lysophospholipids (PC.LPC,PE,PS, PI, PG etc), phosphatidic acids and oxidized lipids. 

6) Preterm birth can be due to preeclampsia, a complex and serious disorder of human pregnancy and the leading cause of fetal and maternal morbidity and mortality worldwide, affecting approximately 5-7% of all pregnancies. Although, the etiology and pathophysiology of this disease remains an enigma, it is accepted that the presence of the placenta, not the fetus, is at the origin of this disease. In collaboration with the Mother and Infant Research Group at Mt. Sinai Hospital, Toronto we investigate normal and abnormal placentation

METHODS USED

Cell and Tissue Culture: Endothelial cells.

Procedures: Elisa, HPLC, gene expression analysis, immunohistochemistry, mass spectrometry, microarrays, proteomics, qRT-PCR, RT-PCR, signal transduction characterization, siRNA, western blot.

EQUIPMENT USED:

Analytical balances, benchtop centrifuge, blotting apparatus, confocal microscope, culture hood, culture incubators, cryostat, digital microscope, dissecting microscope, fluorescence microscope, fresh tissue sectioning systems, gel apparatus, HPLC, infusion apparatus, low- and high-speed centrifuge, low and ultralow freezers, mass spectrometer (GC/MS, LC-MSMS, Imaging Maldi-MS),  mini vortexer, plate reader, real-time/thermocycler, stirrer/hot plate, vibratome.

PRESENT TRAINEES

Sharareh Shojaie (PhD-Physiol)
Sandra Leibel (MSc-Physiol)
Joyce Lee (MSc-IMS)
Michael Litvack (PDF)
Leonardo Ermini (PDF)
Behzad Yeganeh (PDF)

PRESENT COLLABORATIONS

Within the Department of Physiology:
Isabella Caniggia
Brian Kavanagh
Bob Jankov
Jaques Belik
Keith Tanswell
Zdenka Pausova

Outside the Department of Physiology:
Sickkids
Padmaja Subbaroa, Pediatrics & IMS
Felix Ratjen, Pediatrics
Eyal Grunebaum, Pediatrics & IMS
Mingyao Liu, Surgery & IMS
Cecil Pace-Asciak, Pharmacology
Collin McKerlie, LMP
Paul Delgado, Molecular Genetics
Janet Rossant, Molecular Genetics

University of Toronto
Tom Waddell, UHN
Richard Bazinet, Nutrition, UofT

International
Dick Tibboel, Erasmus University, the Netherlands
Johan de Jongste, Erasmus University, the Netherlands
Matthias Roth-Kleiner, Univ of Lausanne, Switzerland
Richard Keijzer, Univ. Manitoba, Canada

Recent Publications

Reviews:

1. Joza, S., Post, M. Development of the respiratory system (including the preterminfant). In:  Neonatal and Pediatric Mechanical Ventilation - From Basics to Clinical Practice. Ed. P. C. Rimensberger, Springer, pp.3-26, 2015.
2. Fox, E., Litvack, M.L., Post, M. Progenitor Cells in Embryonic and Adult Lungs. In:  Stem Cells: from basic research to therapy, Eds.  F. Calegari and C. Waskow, CRC Press: Taylor & Francis, Boca Rotan, pp.308-341, 2014.

Appointments

Department of Pediatrics
Department of Physiology
Department of Laboratory Medicine and Pathobiology