Automated multiscale vessel analysis for the quantification of MR angiography of peripheral arteriogenesis

A modified rat model of hindlimb ischemia for augmentation and functional measurement of arteriogenesis

Arteriogenesis (collateral artery development) is an adaptive pathway critical for salvage of tissue in the setting of arterial occlusion. Rodent models of arteriogenesis typically involve an experimental occlusion (ligation) of a hindlimb artery and then rely on indirect measures such as laser Doppler perfusion imaging to assess blood flow recovery. Unfortunately, the more commonly utilized measures of distal tissue perfusion at rest are unable to account for hemodynamic and vasoactive variables and thus provide an incomplete assessment of collateral network capacity. We provide a detailed description of modifications to the commonly used model of femoral artery ligation. These serve to alter and then directly assess collateral network's hemodynamic capacity. By incorporating an arteriovenous fistula distal to the arterial ligation, arterial growth is maximized. Hindlimb perfusion may be isolated to measure minimum resistance of flow around the arterial occlusion, which provides a direct measure of collateral network capacity. Our results reinforce that arteriogenesis is driven by hemodynamic variables, and it can be reliably augmented and measured in absolute terms. Using these modifications to a widely used model, functional arteriogenesis may be more directly studied.

Low molecular weight fucoidan ameliorates hindlimb ischemic injury in type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Low molecular weight fucoidan (LMWF), extracted from Laminaria japonica Areschoug, is a traditional Chinese medicine, commonly used to alleviate edema, particularly for feet with numbness and pain.

AIM OF THE STUDY

Diabetic mellitus (DM) patients are at high risk of developing peripheral arterial disease (PAD). Individuals with DM and PAD co-morbidity have a much higher risk of critical limb ischemia. LMWF showed several beneficial effects, such as anti-inflammation, anti-thrombosis, and enhancing revascularization. Therefore, we hypothesized that LMWF might be beneficial to diabetes-induced PAD, and investigated the therapeutic potential of LMWF on diabetic PAD rats.

MATERIALS AND METHODS

Type 2 diabetic Goto-Kakizaki (GK) rats were made PAD by injection of sodium laurate into femoral artery. LMWF (20, 40 or 80mg/kg/day) or cilostazol (100mg/kg/day) were given to diabetic PAD rats for 4 weeks, respectively. The effects of LMWF on foot ulceration and claudication, plantar blood flow, collateral vessel formation, endothelium morphology, gastrocnemius injury, platelet aggregation, vessel vasodilation, and the expressions of inflammation factors, VEGF, eNOS, and nitric oxide were measured.

RESULTS

We found that LMWF markedly ameliorated foot ulceration and claudication, and improved the plantar perfusion by reversing hyperreactive platelet aggregation, ameliorating endothelium-dependent vasodilation and revascularization on diabetic PAD rats. In addition, upregulation of several inflammatory factors, such as ICAM-1 and IL-1β in the gastrocnemius muscles of ischemic hindlimb were suppressed by LMWF administration. And eNOS phosphorylation at Ser1177 and NO production were significantly enhanced in LMWF-treated diabetic PAD rats.

CONCLUSIONS

Taken together, our findings demonstrated that LMWF exhibits therapeutic effect on hindlimb ischemia in type 2 diabetic rats likely through ameliorating endothelium eNOS dysfunction and enhancing revascularization, thus, providing a potential supplementary non-invasive treatment for diabetes-induced PAD.

Glyoxalase-1 overexpression partially prevents diabetes-induced impaired arteriogenesis in a rat hindlimb ligation model

We hypothesize that diabetes-induced impaired collateral formation after a hindlimb ligation in rats is in part caused by intracellular glycation and that overexpression of glyoxalase-I (GLO-I), i.e. the major detoxifying enzyme for advanced-glycation-endproduct (AGE) precursors, can prevent this. Wild-type and GLO-I transgenic rats with or without diabetes (induced by 55 mg/kg streptozotocin) were subjected to ligation of the right femoral artery. Laser Doppler perfusion imaging showed a significantly decreased blood perfusion recovery after 6 days in the diabetic animals compared with control animals, without any effect of Glo1 overexpression. In vivo time-of-flight magnetic resonance angiography at 7-Tesla showed a significant decrease in the number and volume of collaterals in the wild-type diabetic animals compared with the control animals. Glo1 overexpression partially prevented this decrease in the diabetic animals. Diabetes-induced impairment of arteriogenic adaptation can be partially rescued by overexpressing of GLO-I, indicating a role of AGEs in diabetes-induced impaired collateral formation.