A Quantitative Trait Locus (LSq-1) on Mouse Chromosome 7 Is Linked to the Absence of Tissue Loss After Surgical Hindlimb Ischemia

Abstract

Background— Peripheral arterial disease (PAD) caused by occlusive atherosclerosis of the lower extremity has 2 major clinical manifestations. Critical limb ischemia is characterized by rest pain and/or tissue loss and has a ≥40% risk of death and major amputation. Intermittent claudication causes pain on walking, has no tissue loss, and has amputation plus mortality rates of 2% to 4% per year. Progression from claudication to limb ischemia is infrequent. Risk factors in most PAD patients overlap. Thus, we hypothesized that genetic variations may be linked to presence or absence of tissue loss in PAD. Methods and Results— Hindlimb ischemia (murine model of PAD) was induced in C57BL/6, BALB/c, C57BL/6×BALB/c (F1), F1×BALB/c (N2), A/J, and C57BL/6J-Chr7 A/J /NaJ chromosome substitution strains. Mice were monitored for perfusion recovery and tissue necrosis. Genome-wide scanning with polymorphic markers across the 19 murine autosomes was performed on the N2 mice. Greater tissue loss and poorer perfusion recovery occurred in BALB/c than in the C57BL/6 strain. Analysis of 105 N2 progeny identified a single quantitative trait locus on chromosome 7 that exhibited significant linkage to both tissue necrosis and extent of perfusion recovery. Using the appropriate chromosome substitution strain, we demonstrate that C57BL/6-derived chromosome 7 is required for tissue preservation. Conclusions— We have identified a quantitative trait locus on murine chromosome 7 (LSq-1) that is associated with the absence of tissue loss in a preclinical model of PAD and may be useful in identifying gene(s) that influence PAD in humans.

Endothelial cell-by-cell profiling reveals the temporal dynamics of VEGFR1 and VEGFR2 membrane localization after murine hindlimb ischemia

“…Hindlimb ischemia was performed by unilateral femoral artery ligation and excision on days 3 and 10 postischemia, as previously described (20,32). Day 3 is a time point that is well studied (32,47,52), providing insights into the early response to ischemic injury at a point when much of the variability that occurs in the postoperative period has resolved and flow and, in most cases, VEGF levels are significantly increased.…”

“…Day 3 is a time point that is well studied (32,47,52), providing insights into the early response to ischemic injury at a point when much of the variability that occurs in the postoperative period has resolved and flow and, in most cases, VEGF levels are significantly increased. Day 10 provides an intermediate time point after ischemic injury, where there is an acceleration in perfusion recovery (20,32). Perfusion flow in ischemic and contralateral nonischemic limbs was measured with the use of laser-Doppler perfusion imaging (Perimed, Stockholm, Sweden) at baseline and at preselected postoperative time points, as previously described (20,32).…”

“…Day 10 provides an intermediate time point after ischemic injury, where there is an acceleration in perfusion recovery (20,32). Perfusion flow in ischemic and contralateral nonischemic limbs was measured with the use of laser-Doppler perfusion imaging (Perimed, Stockholm, Sweden) at baseline and at preselected postoperative time points, as previously described (20,32).…”

“…We have recently optimized a state-of-the-art fluorescence approach, presented here, toward quantitatively profiling VEGFRs on ECs in vitro (37) and ex vivo (36). Our in vitro analysis revealed significant VEGF-mediated shifts in endothelial heterogeneity (37), and our ex vivo analysis identified endothelial heterogeneity in two different mouse strains, whose extensively studied differences in vascular properties and ischemic responses (6,15,20,33,50,51) may serve as proxies for human population variability.…”

Elucidating the Genetic Basis of Peripheral Arterial Disease

“…U sing sophisticated tools of mouse genetics and bioinformatics, a multidisciplinary group of scientists, Dokun et al, 1 have shown that a region of chromosome 7 of a C57BL/6 mouse strain contributes a dominant protective allele (or alleles) that increases limb perfusion and reduces limb necrosis after induction of experimental hindlimb ischemia. The investigators hope that the application of these methods will lead to the identification of genes that might predict the risk of critical limb ischemia in patients with peripheral arterial disease (PAD).…”