Research Location: University of British Columbia - Vancouver Campus

Blood transfusion is a critically important medical procedure used to treat blood loss due to trauma or during surgery; it is also used in the treatment of chronic blood disorders such as thalassemia, sickle-cell disease and other forms of anemia. Due to the presence of blood antigens, however, careful blood typing is necessary to avoid the adverse and sometimes fatal reactions that may result from a mismatched blood type during transfusion. The A and B blood antigens are considered the most clinically important blood antigens. These antigens consist of carbohydrate (sugar) molecules attached to the surface of blood cells. People with type O blood lack the A and B antigens on their red blood cells and thus are often considered “”universal donors”” (not accounting for minor antigens), yet units of type O blood are frequently in short supply due to high demand. The use of enzymes to remove A and B antigens is a potential means of generating universal blood donor cells from blood types other than O. Dr. David Kwan’s research aims to investigate methods for the enzymatic removal of blood antigens from blood cells. Although enzymes that remove the A or B antigens to convert red blood cells have been discovered, they have low efficacy. Recently a new enzyme called EABase was discovered, which can efficiently remove the B antigen but only slowly removes the A antigen from red blood cells. The primary focus of Dr. Kwan’s work will be to engineer the EABase enzyme using “”directed evolution”” techniques to improve the efficiency of EABase in removing blood antigens so that it may be a more efficient catalyst for the conversion of A-, B- and AB-type red blood cells into “”universal blood cells.”” A secondary focus, in collaboration with the Centre for Blood Research, will test the use of polymer additives to enhance the rate of enzyme action. Over 15 million units (approximately 450 ml per unit) are collected for preparation of blood products in Canada and the United States per year. The ability to generate universal blood donor cells would be a breakthrough development, allowing transfusion without the need to find a positive match and tremendously improving the supply of blood while increasing the safety of blood transfusions.

Complex surgical procedures on the face, such as jaw reconstruction, frequently result in problematic scars that may be aesthetically upsetting for the patient or can interfere with chewing or swallowing. An accurate facial computer model of a patient’s face could allow surgeons to test different surgical incision pattern designs before surgery to determine which design is likely to result in the best outcome. A computer model of a patient’s face must take into account the complex properties of facial skin, such as the variability of stretch depending on direction. This requires experimental data from tests on a real human face; however, there is little data available at present about the stiffness of facial skin and soft tissues. The goal of Dr. Cormac Flynn’s research is to determine how the complex properties of facial skin affect our chewing and swallowing actions and how facial scars interfere with these functions. He aims to develop a computer model of the face with the most accurate representation of facial skin possible. To do this, he will use a biomedical device to determine the stiffness and thickness of skin and soft tissue below the skin surface of volunteers. His second task will be to use a small robotic device to apply small forces to a volunteer’s face and measure how much the skin surface deforms. The force will be applied to a number of points on the face in succession to provide a rich set of data that will be used to develop the skin model. Dr. Flynn will determine appropriate computer models to represent the skin and underlying soft tissue and apply his data from the first two experiments to set the parameters. Finally, he will merge the face model with an existing computer model of the jaw and tongue developed at UBC. The ability of the resulting model to simulate chewing and swallowing will be compared with existing computer models. This research will provide crucial knowledge about how facial skin and the underlying soft tissues influence chewing and swallowing, and will be used in the development of a computer model that surgeons can use to improve both reconstructive surgery outcomes and quality of life for patients.

Within each individual cell, different proteins are localized to specific and necessary locations. There are many different ways these proteins are directed to where they need to go. One method for influencing protein localization is palmitoylation, which is the addition of a lipid molecule, specifically palmitate, to the protein. Protein localization is especially important in neurons, where synaptic proteins need to be carefully organized and localized to the pre- and post-synaptic regions of the neuron in order to accurately convey messages from one neuron to another. In Huntington's disease, which is characterized by neuronal death and subsequent severe motor and cognitive disturbances, it appears that synaptic proteins are mis-localized outside of the synapse, which causes synaptic dysfunction prior to cell death and symptom onset. Preventing this early synaptic dysfunction is believed to be a viable means of preventing or significantly delaying cell death and Huntington’s disease symptoms. Previous work has suggested that the level of palmitoylation is decreased in Huntington’s disease and that this may contribute to early synaptic protein dysfunction. Dr. Matthew Parsons is working to determine how the palmitoylation of specific synaptic proteins regulates their localization within the synapse and how this relates to the synaptic dysfunction observed in Huntington’s disease. Specifically, he is using different techniques to compare the properties of synaptic communication, synaptic protein localization and neuronal vulnerability to cell death in mice that have Huntington’s disease and mice with reduced protein palmitoylation. He will also use neuronal cultures from wild-type animals to investigate the effects of experimentally manipulated protein palmitoylation. Should the synaptic dysfunction due to decreased palmitoylation resemble the synaptic dysfunction in Huntington’s disease, he will also attempt to rescue the early Huntington’s disease phenotype by overexpression of a protein known to promote palmitoylation. These studies will help determine whether the regulation of synaptic protein palmitoylation may be a viable target for the treatment of Huntington’s disease.

Sufficient blood flow to the brain is critical for normal brain function. In response to increased brain activity, a local increase in blood flow to the active area is required to supply extra oxygen and glucose. This increase in blood flow is controlled by signaling molecules, which are released by neurons and astrocytes and can regulate blood vessel diameter. Dr. Clare Howarth will investigate how brain blood flow is controlled in response to increases in brain activity and how this is impaired in disease. In particular, she will be studying the role that astrocytes, a type of brain cell, play in the regulation of brain blood flow. One of the signaling molecules released by astrocytes, prostaglandin E2, can result in blood vessel dilation. Dr. Howarth’s hypothesis is that following a stroke, astrocytes have a decreased ability to produce prostaglandin E2, and this contributes to the long-lasting failure of blood vessels to dilate, leading to increasing neuronal damage. Using multi-photon imaging techniques, she will observe what happens to blood flow in the brain when astrocytes are stimulated with pharmaceutical or light-activated agents under conditions where the production of these signaling molecules is compromised. She will also investigate whether pharmaceutical therapies are able to reverse the effect, allowing blood vessels to dilate and help recover brain function after a stroke. This work will advance our understanding of how brain blood flow is regulated in response to neural activity. This knowledge is essential to understanding normal brain function, functional imaging techniques, and what occurs when the brain energy supply is cut off in disorders such as a stroke.

Blood transfusion has a vital role in modern medicine. Not only is it required in surgery, or for the treatment of acute trauma, but patients with disorders such as thalassemia major and sickle cell anemia require chronic transfusion therapy on an ongoing basis. In chronic transfusion therapy, matching of minor antigens besides the major ABO and RhD antigens is essential; unintentional mismatching of red blood cells remains one of the most common causes of serious and fatal adverse reactions following transfusion. Creation of universal donor red blood cells has the potential to significantly decrease such incidents. Presently, there is no method available for the generation of antigen- red blood cells, in part because of the complexity of proteins on the surface of red blood cells. Previous attempts to create universal donor red blood cells include enzymatic cleavage of terminal immunodominant sugars and the covalent attachment of hydrophilic polyethylene glycol (PEG) polymers to surface proteins on red blood cells to camouflage the antigens. Enzymatic cleavage remains expensive and PEG-grafted red blood cells demonstrated shortened circulation in animal models. Dr. Rafi Chapanian’s research aims to use a novel cell-surface engineering method that combines grafting of highly biocompatible polyglycerol polymers and enhanced enzymatic cleavage of AB antigens to create universal donor red blood cells. He will develop a new powerful class of enzymes that can simultaneously remove group A and B antigens. He will use neutral additive polymers to enhance the efficiency of enzymatic cleavage and will investigate polymer grafting to make the process cost effective. Dr. Chapanian will synthesize linear, branched, and umbrella-like polyglycerol-based polymeric structures and graft them to the primary amines of proteins on the surface of red blood cells. These polyglycerol polymers are highly biocompatible, non-immunogenic and are expected to be superior to PEG polymers. Modified red blood cells will be characterized using standard in vitro testing methods and ultimately will be injected in mice to investigate their circulation. This research holds great promise for the cost-effective generation of antigen- red blood cells and has the potential to significantly improve the blood supply and enhance transfusion safety.

The cortex is a thin layer on the surface of the brain where most information processing takes place. The cortex is separated into several layers. There are large numbers of neural interconnections that exist between the different cortical layers, as well as many connections with neurons of the spinal cord. In the somatosensory cortex, where the perception of touch is analyzed, there is a spatial representation of the body on its surface. The same type of spatial organization exists in the motor cortex, controlling the body's muscles; however, the spatial organization of the motor cortex is not as well defined, and this characteristic allows for more change and adaptation during learning or in motor recovery after a stroke.

Dr. Matthieu Vanni will explore the participation of independent neurons in the different layers of the motor cortex of the mouse. The mouse is a model that will be used in these studies because it provides opportunities to manipulate the genome, which will be a major asset in stages of this project. Dr. Vanni will be measuring the activation of identified neurons using two-photon microscopy, which achieves a sub-cellular resolution in living tissue. The neuronal activation in the motor cortex will be measured in response to natural movements and/or following excitation/inactivation of individual neurons of the network.

The results of this study will help to better understand the information processing of motor tasks in the brain. This knowledge could have an impact on the understanding of how the brain adapts during learning and after stroke. Furthermore, understanding these cellular aspects will have important implications in the design of therapeutic rehabilitations such as prosthetic or brain stimulation, limiting post-stroke physical disability. This project will use novel applied optical methods: two-photon microscopy and optogenetics. The exceptional resolution and specificity of these new methods will have a strong impact in many other fields as well; for example, they may be applied to study neural compensation mechanisms observed in neurodegenerative diseases such as Alzheimer's or Parkinson's.

Endogenous retroviruses (ERVs) are viral DNA sequences that have repeatedly inserted themselves through the course of primate evolution and in turn become an integral part of the human genome. The human genome contains more than 200 families of ERVs, which together comprise approximately 8 percent of our chromosomal DNA. A growing body of evidence indicates that ERVs have been a major player in molecular evolution and continue to impact the mammalian genome by acting as insertional mutagens, inducing DNA rearrangements and altering gene regulation. Given the potential for harmful effects, it is not surprising that mammals have evolved multiple lines of defense against these endogenous retroviruses, such as modifying the DNA or chromatin structure to prevent the genes from being expressed. In theory, if the ERVs are de-repressed, they could become active and then cause disruptive events leading to cancer. Although the structure, function and impact of human ERVs (HERVs) on the human genome has been studied in detail, their potential contribution to cancer has not been systematically examined. Dr. Mohammed Mahdi Karimi will be applying his experience in bioinformatics methods and high-throughput epigenetic analyses to study HERV families in human cancers. He will examine gene expression patterns and different types of epigenetic modifications, including histone modifications and DNA methylation, in primary lymphocytes isolated from lymphoma patients as well as in cell lines. By identifying the epigenetic changes in the genomes of HERV families, he hopes to determine how abnormal gene expression leads to the development of human lymphomas. Dr. Karimi expects that the results from this initial analysis will reveal genes that are misregulated in cancer as a result of the de-repression of HERVs, and this misregulation will be reflected in changes to the DNA or chromatin modification. The ultimate goal of Dr. Karimi’s research is to identify molecular or epigenetic pathways that are perturbed in different types of human lymphomas, which in turn may potentially be targeted with new therapeutic strategies.