STAT3 activated stem cell

Patent Number: 7,510,870

One of the major problems in stem cell research is how to maintain the stem cell in an undifferentiated state while allowing for it to continue proliferating.  In the area of embryonic stem cells this was solved by the discovery that leukemia inhibitory factor (LIF) would maintain mouse embryonic stem cells in an undifferentiated state.  For human embryonic stem cells this issue was initially addressed with feeder layers and subsequently with feeder-free systems. 

The current patent teaches the use of "protein" engineering of adult stem cells so as to specifically inhibit differentiation.  The patent covers the protein transfection of the STAT3 (signal transducer and activator of transcription-3) protein into "human hematopoietic stem cells" by use of the Protein Transduction Domain (PTD) sequence being added to the STAT3 sequence. 

STAT3 is a protein that has been implicated in numerous biological functions including stem cell self-renewal.  STAT3 is activated in stem cells by the stem cell stimulant G-CSF.

One pitfall of this patent is the possibility of oncogenesis, in fact STAT3 has been implimented in aggressive leukemias and resistance to chemotherapy (Bewry et al. Mol Cancer Ther. 2008 Oct;7(10):3169-75).  Perhaps this is why the inventors use protein transfection which arguably may be transient as opposed to genetic transfection.

View this patent on the USPTO website.