Research Spotlight: Dr. Peter Grabham

Dr. Peter Grabham is one of the lead researchers and a faculty member of the Center for Radiological Research. His laboratory investigates the effects of harmful agents like radiation on the human microvascular system. The microvascular system (small capillaries) is crucial to healthy functioning of the tissues and its dysfunction is not only a primary event in a range of degenerative diseases but also an important influencing factor in many others.  Dr. Grabham uses 3D human tissue models of human microcapillaries to investigate the effects of harmful agents on vascular function. He has also enhanced the process of developing three dimensional tissue samples for 3-D tissue modeling and has ongoing research into the development of 3D tissue models that include other cell types that more accurately depict tissues in the human body. 
 
The research targets two processes that are vital to normal vascular and general health.
1. The function of the endothelial barrier - the Interface between the blood and the tissues, a semipermeable barrier that controls blood–tissue exchange of fluids, nutrients, and metabolic wastes.
2. Angiogenesis - The growth of new or replacement vascular pathways.
 
Radiation and microvessels
    A major part of the research is the study of how ionizing radiation affects the human microvasculature.  This includes the effects of charged particle radiation found in the space environment and the effects ionizing radiation from different types of radiotherapy.  Grants from the National Aeronautics and Space Administration (NASA) have funded studies on the effects of space radiation on astronauts. These studies have determined the doses and types of radiation that are harmful to the human microvasculature (e.g. Figure 1).  Current investigations are centered on the effects of space radiation in addition to microgravity on the human vasculature and thus advance our knowledge of the health consequences of space travel. In order to effectively investigate the effect of microgravity and radiation on vascular tissue Dr. Grabham and the Center’s Instrument Shop developed a microgravity simulator that can house 2-dimensional and 3-dimensional tissue samples. The initial findings of this ongoing research suggest that microgravity has an effect on the angiogenesis of vascular tissue in mature vessel models and that radiation tends to breakdown the endothelial barrier making it more permeable and thus susceptible to a diseased state. Further research on the effect of both microgravity and radiation on tissue models is currently being performed.
 
3D human tissue development
     An additional focus of the laboratory is the development of 3-dimensional human tissue models using human cell types from various sources.  Cells can be grown together to produce normal tissue such as the brain tissue model or the ‘neurovascular unit’ which contains capillaries, neurons and astrocytes (Figure 2).  Ongoing research is focused on incorporating more relevant human cell types.  Cells can also be grown together to reproduce pathological tissue such as the brain cancer glioblastoma with its associated vasculature (Figure 3) a useful model for cancer research.   
     The development of 3-dimensional human tissue models from normal human cells and stem cells has great potential in many fields of medical research.  Tissue models can more accurately depict human tissue since the cells can be arranged spatially as they would be in a living organism and can interact with each other as they would in the human body.
 
For more detailed descriptions of the research contact the Center for Radiological Research.

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