Abstract 222: N-Acetylcysteine Enhances Amputation Stump Healing and Perfusion in Diabetes

Abstract

Over 150,000 extremity amputations are performed in the US per year. More than 60% of these are performed in patients with diabetes and peripheral arterial disease, and 25% require subsequent re-amputation due to poor surgical site healing. The mechanisms underlying poor amputation stump healing in the setting of diabetes are not understood, which greatly limits management options. N-acetylcysteine (NAC) is a well-known thiol that regulates intracellular glutathione levels, promotes endothelial cell function and angiogenesis, and is proposed to have therapeutic benefits in the setting of diabetes. To test the hypothesis that NAC can improve surgical site healing in chronically ischemic amputation stumps in the setting of diabetes, we developed a novel in vivo murine hindlimb ischemia-amputation model. In this model, streptozotocin-treated C57B6 mice are allowed to develop hyperglycemia for 1 month, followed by unilateral hindlimb femoral artery ligation. After 1 week, the recovered yet still mal-perfused hindlimb undergoes an infrageniculate amputation. Compared to sham control, mice receiving a daily intraperitoneal administration of NAC 150mg/kg demonstrated a 31% improvement in stump healing (P=0.06), 160% increase in hindlimb stump laser-Doppler perfusion at 3 days post-amputation (P=0.03), as well as 179% increase in hindlimb adductor muscle neovascularization (P=0.01). Adductor muscle segments from ischemic amputated hindlimbs also demonstrated less muscle damage, and expressed higher levels of de-palmitoylated activated Gaq (P<0.05), which is essential for ischemia-induced neovascularization. Similarly, HUVECs treated with NAC 3mM demonstrated a transient 19% increase in de-palmitoylated Gaq (P=0.03), suggesting a novel mechanism of action for NAC. These findings demonstrate that NAC may have important therapeutic benefits in amputation stump healing in the setting of diabetes, which may translate into a valuable treatment option in vulnerable patient populations.