Question:

The tyrosine phosphatase SHP2 has been shown to influence endothelial cell proliferation and apoptosis via the Akt and MAPK/ERK pathway. In particular, SHP2 knockdown has been demonstrated to disrupt angiogenesis in vitro and in vivo offering a promising target for anti-angiogenic therapies. For cancer therapy a local, site-specific targeting is needed to prevent side-effects. Therefore we developed a method for local SHP2 knockdown using complexes of lentiviral vectors and magnetic nanoparticles (MNPs) in combination with magnetic fields.

Method:

Transgenic murine Flt-eGFP embryonic stem cells were differentiated into the endothelial lineage using the embryoid body (EB) method. After dissociation of the EBs eGFP+ endothelial cells formed again vascular networks. SHP2 knockdown was performed by the combined use of a lentiviral small hairpin SHP2 construct and MNPs. Site-specific transduction was achieved with the help of a magnetic tip generating a local magnetic field.

Result:

MNP-assisted lentiviral transduction of differentiated ES cells for 30 minutes enhanced protein knockdown of SHP2 when compared with classical over night transduction. In addition, 10 days after transduction the total tube length and the number of branching points of newly formed vessels was strongly reduced. Recent experiments also indicate that a local transduction can be obtained by the use of specially designed magnetic fields.

Conclusion:

SHP2 is a promising target for anti-angiogenic therapies. Application of MNPs and magnetic fields enhances lentiviral mediated SHP2 knockdown efficiently and this approach also provides the option of site-specific modulation of angiogenesis.