Harvard researchers genetically 'edit' human blood stem cells

PUBLIC RELEASE DATE:

6-Nov-2014

Contact: B. D. Colen bd_colen@harvard.edu 617-413-1224 Harvard University @HarvardResearch

Harvard Stem Cell Institute (HSCI) researchers at Massachusetts General (MGH) and Boston Children's hospitals (BCH) for the first time have used a relatively new gene-editing technique to create what could prove to be an effective technique for blocking HIV from invading and destroying patients' immune systems.

This is the first published report of a group using CRISPR Cas technology to efficiently and precisely edit clinically relevant genes out of cells collected directly from people, in this case human blood forming stem cells and T-cells.

Though the researchers that believe this new approach to HIV therapy might be ready for human safety trials in less than five years, they themselves offered three strong points of caution:

The first and most obvious is that they could run into unexpected complications; the second is that the history of the HIV/AIDS epidemic is littered with "cures" that turned out not to be; and finally, even if this new approach works perfectly, it will require additional developments to be applicable in the areas of the world that have been the hardest hit by the epidemic.

The work, led by Chad Cowan, and Derrick Rossi, associate professors in Harvard's Department of Stem Cell and Regenerative Biology, is featured on the cover of today's issue of the journal "Cell Stem Cell."

HIV specifically targets T cells, a principal portion of the blood-based immune system, and enters via a gene receptor called CCR5 that serves as a doorway into the cells. Once inside the T cells, HIV replicates and kills off the host cells, leaving patients at the mercy of a variety of opportunistic infections.

Using the CRISPR Cas gene-editing technology, the Cowan and Rossi teams knocked the CCR5 receptor out of blood stem cells that they showed could give rise to differentiated blood cells that did not have CCR5. In theory, such gene-edited stem cells could be introduced into HIV patients via bone marrow transplantation, the procedure used to transplant blood stem cells into leukemia patients, to give rise to HIV-resistant immune systems.

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Harvard researchers genetically 'edit' human blood stem cells