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New method allows stem cells to be imaged in heart
Issue date: 11/20/08
The promise of stem cell therapies is growing ever closer to becoming realized in the medical setting. In a recent study, a team from the Hopkins School of Medicine used imaging technology to watch adult cardiac stem cells as they colonized the injured heart of a rat.
A major stepping stone before stem cell therapies that can be routinely used in human subjects is the ability to observe the progression of the stem cells repairing the tissue of interest.
A physician must know exactly what type of cell they are using on a patient, where this cell is being injected and also what this cell's behavior is upon transplantation.
The members of the Hopkins team, led by multiple researchers from the cardiology and radiology departments, collaborated to image cardiac stem cells growing on the hearts of rats that had undergone a simulated heart attack.
The researchers isolated cardiac stem cells - the adult stem cells that maintain the heart - and then labeled these cells with a novel protein that allows them to image the cell while they are inside the animal. This protein is known as NIS, for sodium (Na)-iodide symporter, and is normally expressed in the thyroid.
Cancer researchers take advantage of its selective uptake of iodine, which allows targeting of cancerous thyroid cells through their radioactive iodine uptake and, consequently, killing of those cancer cells specifically. A symporter is a type of protein that can import multiple small molecules into the cell, in this case sodium and iodine.
The researchers then created cardiac stem cells that express NIS on their surface, allowing these cells to selectively take in iodine from their surroundings. The transgenic expression of NIS was necessary for the CT imaging once the cells were injected.
The promising aspect of this method is that uptake of the specific iodine used in this study is non-toxic to cells, and it can be visualized by cameras which pick up the energy released by the iodine.
A major stepping stone before stem cell therapies that can be routinely used in human subjects is the ability to observe the progression of the stem cells repairing the tissue of interest.
A physician must know exactly what type of cell they are using on a patient, where this cell is being injected and also what this cell's behavior is upon transplantation.
The members of the Hopkins team, led by multiple researchers from the cardiology and radiology departments, collaborated to image cardiac stem cells growing on the hearts of rats that had undergone a simulated heart attack.
The researchers isolated cardiac stem cells - the adult stem cells that maintain the heart - and then labeled these cells with a novel protein that allows them to image the cell while they are inside the animal. This protein is known as NIS, for sodium (Na)-iodide symporter, and is normally expressed in the thyroid.
Cancer researchers take advantage of its selective uptake of iodine, which allows targeting of cancerous thyroid cells through their radioactive iodine uptake and, consequently, killing of those cancer cells specifically. A symporter is a type of protein that can import multiple small molecules into the cell, in this case sodium and iodine.
The researchers then created cardiac stem cells that express NIS on their surface, allowing these cells to selectively take in iodine from their surroundings. The transgenic expression of NIS was necessary for the CT imaging once the cells were injected.
The promising aspect of this method is that uptake of the specific iodine used in this study is non-toxic to cells, and it can be visualized by cameras which pick up the energy released by the iodine.
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