Magnetocapsules show Promise in Immunoprotecting Islet Transplants

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G. Magnetocapsule containing encapsulated mouse pancreatic islet cells. (Copyright Nature Medicine, 2007.)

The national media recently featured stories about the research of Johns Hopkins University and Institute of NanoBioTechnology affiliated faculty members Jeff Bulte and Dara Kraitchman and other colleagues. The news was based on a technical report in Nature Medicine explaining how magnetocapsules—tiny capsules about 350μm in diameter made from a matrix of seaweed extract and iron—could help prevent the rejection of insulin-cell (islet) transplants in diabetics.

The semi-permeable magnetocapsules have pores large enough to allow the insulin to pass through but small enough to prevent antibodies directed against β-cells from the pancreas from entering and attacking. Magnetic resonance imaging was used to track delivery and engraftment.

The capsules were tested in the abdominal cavity of diabetic mice and in the liver of swine with promising results. In the mice, blood sugar levels returned to normal within a week. In swine, the capsules were reported to be releasing usable levels of insulin for at least three weeks.

Bulte, a professor of radiology and chemical and biomolecular engineering, says this research demonstrated the potential that the magnetcapsules may reduce the need for anti-rejection drugs in people with type 1 diabetes who have received islet transplantation.

The research was funded by the National Institutes of Health and the Howard Hughes Medical Institute. A list of Bulte’s and Kraitchman’s research interests may be found at

To access the full text article, Barnett, B.P., Arepally, A., Karmarkar, P.V., Qian, Wesley, D. Gilson, Piotr, Walczak, D., Howland, V., Lawler, L., Lauzon, C., Stuber, M., Kraitchman, D.L., Bulte, J.W.M. (Aug. 1, 2007). Magnetic resonance-guided, real-time targeted delivery and imaging of magnetocapsules immunoprotecting pancreatic islet cells. Nature Medicine 13, 986-991 as a pdf, go to

Read the abstract from PubMed, click here

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