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Johns Hopkins Bloomberg School of Public HealthCAAT

Research Grants 1998-1999

Summary of Research Grants

In Vitro Evaluation of Pharmacological Interventions Aimed to Prevent Atherosclerosis
Rita B. Alevriadou, PhD
Johns Hopkins University, Baltimore, Maryland
In vivo experimental evidence indicates that monocytes bind more avidly to epithelial cells (ECs) in hypercholesterolemic animals, and enter the intimal space where they contribute to the formation of fatty streaks. Hypercholesterolemia also causes an increased production of oxygen free radicals by ECs. In vitro studies using cultured ECs treated with minimally-modified (mildly-oxidized) low-density lipoprotein (MM-LDL) have shown that these cells promote the atherosclerotic process by expressing proinflammatory and procoagulant activity (increased synthesis of monocyte chemotactic protein-1 and tissue factor, and decreased production of nitric oxide). Alevriadou and colleagues seek to:

  1. understand the relative contributions of each one of the changes that MM-LDL causes in EC function, to the adhesive interactions between blood cells (monocytes, lymphocytes, platelets) and ECs at the early stages of atherosclerosis, and
  2. propose better treatments that would either prevent or delay the progression of the disease. Previously, the investigator designed a perfusion system of cells in suspension over EC-coated surfaces, coupled with video microscopy and digital image processing, that allows us to quantity the adhesion of flowing blood cells onto cultured ECs.

Currently, the laboratory is working to:

  1. Evaluate the in vitro model by perfusing samples of mixed suspensions of leukocytes and platelets over EC monolayers, preincubated or not with MM-LDL, visualizing the adherent cells by phase-contrast microscopy, and quantifying cell-cell interactions.
  2. Compare the ability of key antioxidants, such as vitamin E (a-tocopherol), to restore the lack of interactions between flowing blood cells and MM-LDL-treated ECs. Ultimately, Alevriadou plans to use an in vitro perfusion model to assess the relative potencies of key pharmacological agents currently used for prevention/treatment of atherosclerosis and cardiovascular disease (besides cholesterol-lowering drugs).

Dopamine Neurons from Progenitor Cells: An Alternative to the Use of Fetal Tissue
Paul M. Carvey, M.S., PhD
Rush-Presbyterian St. Luke's Medical Center, Chicago, Illinois
Every year, thousands of animals are killed in order to provide cells for study in tissue culture. These cells are taken from fetuses and then grown in a dish (tissue culture) so that their function can be studied in a very controlled fashion. This is a labor-intense procedure that is also very expensive. Carvey and colleagues recently discovered a cell in the brain (called a progenitor cell) that will divide in the laboratory like a tumor cell. They also discovered that if they add certain chemicals to the media in which these cells are growing, they can force them to turn into a certain type of nerve (called the dopamine neuron) that is widely studied in tissue culture situations. Carvey proposes to fully characterize the dopamine resulting from the conversion process so that the scientific community will feel comfortable using these cells instead of taking cells from pregnant animals. Specifically, Carvey and colleagues plan to demonstrate that the converted dopamine neurons exhibit seven of the major characteristics natural dopamine neurons have. The dopamine neurons yielded by progenitor cells are less expensive and less time consuming to produce than cells derived from fetal tissue.
Experiments Using a Computer Model of the Immune System
Franco Celada, MD, PhD
Hospital for Joint Diseases-Rheumatology, New York City, New York
Celada and colleagues are collaborating with Philip Seiden, a physicist and research staff member emeritus at IBM's T.J. Watson Research Center to construct a model immune system in the computer and conduct experiments with it. By showing that their model can be applied to real research problems they hope to foster its use by more and more immunologists (and, eventually, biologists), thereby catalyzing a cultural transition among bench scientists.
ES-Derived Neurons and Glia: a Novel Cell Line Model for CNS Testing
David I. Gottlieb, PhD
Washington University School of Medicine, St. Louis, Missouri

Final Report

Embryonic stem (ES) cells of the mouse straddle the world of normal cells and tissue culture cell lines. In one type of culture they replicate indefinitely as undifferentiated cells and provide an infinite source. When transplanted into an early embryo, they integrate into the host and, under guidance of the normal cues of development, differentiate into all cell types of the host's body. ES cells are thus "stem cells for the whole body." Previously, Gottlieb and colleagues discovered a method of giving cultures of ES cells instructions so that they differentiate into neurons and glia. The resulting neurons have all the basic properties of normal neurons from the brain. Thus, it is possible to go from rapidly dividing stem cells all the way to mature and functional neurons entirely in a dish. Such a system should be ideal for testing chemicals for CNS toxicity. The investigator plans to test the effects of lead and alcohol on ES-derived neurons and compare the effects to those on cultured neurons from the brain. Gottlieb hypothesizes that the effects of lead and alcohol should be very similar in both systems, demonstrating that ES-derived neruons and glia are a valid alternative to cultured barin neurons. Because ES cells replicate indefinitely in culture they have the potential to greatly reduce the usage of animals in testing for neurotoxicity.