Gene silencing therapy for in situ elastic matrix regenerative repair

Statement of Purpose: Proteolytic disorders, exemplified by abdominal aortic aneurysms (AAAs), aortal expansions are characterized by disruption of elastic fibers by overexpressed matrix metalloproteases (MMPs). These conditions are difficult to reverse since adult cell types are highly deficient in generating elastin precursors and in their ability to regenerate or repair elastic fibers. Treatments are thus mandated to provide both an elastogenic impetus and anti-proteolytic stimuli. Previously, we showed doxycycline (DOX), an MMP inhibitor drug, delivered at low µg/mL doses to provide these dual effects in aneurysmal smooth muscle cell (SMC) by inhibiting the regulatory protein c-Jun-N-terminal kinase (JNK)¹. DOX inhibition of the JNK-2 isoform resulted in attenuation of elastolytic MMP-2 and increases in TGF-β1 in a dose-dependent manner; the latter increased elastogenesis & lysyl oxidase (LOX)-mediated crosslinking of elastin. Due to non-specificity of DOX for JNK2, we presently investigated effects of JNK2 gene silencing using anti-JNK2 siRNA complexed with a transfection vector poly-ethylenimine (PEI).