Cellular and molecular mechanism regulating blood flow recovery in acute versus gradual femoral artery occlusion are distinct in the mouse

A-C, Laser Doppler images of blood flow in the calf and foot after induction of acute vs gradual arterial occlusion. Blood perfusion was monitored with LDPI at different time points: preoperation (Pre), operation day (OP), postoperative day 7, 14, and 35 (PO 7, PO 14, and PO 35, respectively). White arrow and arrowhead indicate the blood perfusion in ischemic leg on the operation day after induction of acute (A) and gradual (B) arterial occlusion, respectively. The gradient color scale from white to dark blue indicates the blood perfusion level (high to low). White and black frame indicate the areas of foot and calf scanned by LDPI, respectively. The y-axis of (C) shows the ratio of the blood flow in the left (operated) over right (nonoperated) calf muscle. The x-axis shows different time points of LDPI measurement.

*Statistically significant (P < .05); M ± SEM, n = 14.

Gene expression in calf muscle after induction of acute or gradual arterial occlusion. Q-RT-PCR was used to determine gene expression level of HIF-1α (A), VEGF (B), NF-κB (C), Egr-1 (D), PDGF (E), MCP-1 (F), ICAM (G), and VCAM (H) in calf muscle after induction of acute vs gradual arterial occlusion. Gene expression values at different time points are displayed along the y-axis as the ratio of mRNA from the left calf muscle in ischemic mouse group over mRNA from left calf in the sham control mice.

*Statistically significant differences (P < .05) between groups were shown by linkage. The error bars represent the standard deviation in each group (n = 4).

Gene expression in thigh muscle after induction of acute or gradual arterial occlusion. The expression of eNOS (A), Egr-1 (B), PDGF (C), MCP-1 (D), ICAM (E), and VCAM (F) in thigh muscle after induction of acute or gradual arterial occlusion was examined by Q-RT-PCR. The y-axis shows the gene expression values expressed as the ratio of mRNA of the thigh from the side of arterial occlusion over mRNA of the thigh in sham control mice. The x-axis shows the different time points (seeFig 2) in each group.

*Statistically significant differences (P < .05) between groups were shown with linkage. The error bars represent the standard deviation in each group (n = 4).

Angiogenesis and arteriogenesis including angioscore and collateral diameter after acute vs gradual occlusion. A-D, Capillary immunostaining (CD31) and quantitative analysis of capillary density in calf muscle on postoperative day 35. Representative images from control (A), acute arterial occlusion (B), and gradual arterial occlusion (C) groups are shown. Capillary density, expressed by the ratio of number of capillaries over muscle fiber (y-axis), was significantly greater in calf muscle in the acute arterial occlusion group (n = 9) than in the gradual arterial occlusion group (n = 7), or in normal muscle (n = 4) (D). E and F, Angioscore and collateral diameter in acute vs gradual arterial occlusion.

Angiograms were performed on mice with acute vs gradual arterial occlusion on post-operative day 35. Angioscore tended to be higher after acute arterial occlusion than after gradual arterial occlusion, although the difference between the two groups was not statistically significant (P = 0.18). (F) The diameters of the three largest collateral arteries in both the acute and gradual occlusion models were measured using Fovea Pro software. There was no statistically significant difference between the models.

*P < .05.

**P < .01.

A-G, Muscle necrosis detection and macrophage immunostaining in gastrocnemius 3 days after acute vs. gradual arterial occlusion. A-D, Arrows in (A) and (B) show necrotic areas after acute and gradual occlusion. C and D show the same figure of (A) and (B) at higher magnification, respectively. Star identifies the area of necrosis in (C). E and F, The immunostaining of macrophages (Cy3 labeled) in gastrocnemius (white arrows) after acute arterial occlusion (E) and after gradual arterial occlusion (F).

Double immunostaining of SDF-1α and CD31 in gastrocnemius and thigh muscle 3 days after acute vs. gradual occlusion. Arrows showed part of SDF-1α positive cells after acute (A) and gradual (B) occlusions in gastrocnemius. C and D showed the similar results of SDF-1α and CD31 double staining in thigh muscle after acute (C) and gradual occlusion (D).

Hemangiocyte immunostaining with VEGFR-1 and CXCR4 in gastrocnemius and thigh muscles 3 days after acute vs gradual occlusion. Some cells are single stained for VEGFR-1 (green) or CXCR4 (red), hemangiocytes are positive for both VEGFR1 and CXCR4, labeled by arrows. More hemangiocytes are identified after acute occlusion (A) and (C) than after gradual occlusion (B) and (D) in both gastrocnemius (A) and (C) and in thigh muscle (B) and (D).

More hemangiocytes are integrated into the small vessels in thigh muscle 7 days after acute occlusion. More hemangiocytes were detected in thigh muscle at post occlusion day 7 after acute occlusion (A) than after gradual occlusion (B). The enlargement of images (A) and (B) are shown in (C) and (D), respectively. Asterisks show the lumen of small vessels. Arrows show the hemangiocytes, which are double positive for both VEGFR-1 and CXCR4. Hemangiocytes line along the endothelium of a small vessel. The quantitative analysis of hemangiocytes in each field at different time points postocclusion is shown in (E).

*Indicates P < .01.