Angiogenesis in the latissimus dorsi muscle using different regimens of electrical stimulation and pharmaceutical support

Deferoxamine enhances neovascularization and recovery of ischemic skeletal muscle in an experimental sheep model

BACKGROUND

Iron chelators have been reported to interfere with inflammatory cells and possibly enhance vascular growth factor expression. The objective of this study was to investigate the efficacy of the iron chelator deferoxamine mesylate in preventing skeletal muscle ischemia.

METHODS

The latissimus dorsi muscle (LDM) was mobilized in 20 adult sheep. Two separate pockets were created in each sheep. Autologous fibrin sealant with or without 100 mg/mL of deferoxamine mesylate (10 pockets) was added to the pockets. Deferoxamine mesylate alone was also applied to another 10 pockets, whereas the 10 other pockets served as controls.

RESULTS

Conventional, indirect immunofluorescent enface staining showed that in nonmobilized, nonischemic LDM the capillary density was 196 +/- 14 capillaries/mm2 in the distal and 207 +/- 19 capillaries/mm2 in the middle part. After severe ischemic shock (subtotal mobilization), the muscle did not recover completely even after 2 months (149 +/- 15 capillaries/mm2 in the distal part and 177 +/- 16 capillaries/mm2 in the middle part of the LDM). Fibrin application only increased muscle neovascularization. The number of capillaries per mm2 of muscle increased to 250 +/- 25 in the distal part and to 271 +/- 24 in the middle part of the LDM. However, when fibrin was applied with added deferoxamine mesylate, the capillary density increased to 361 +/- 25 capillaries/mm2 in the distal part (p < 0.05 vs fibrin only; controls) and to 401 +/- 20 capillaries/mm2 in the middle part of the LDM (p < 0.05 vs fibrin only and p < 0.001 vs controls). The data are concordant with the blood flow estimation before and after mobilization (severe ischemic shock) in the different parts of the LDM.

CONCLUSIONS

Local application of deferoxamine mesylate enhances neovascularization and recovery of surgically induced skeletal muscle ischemia in a sheep model.

Slowed progression or elimination of atherosclerosis by low-frequency electrical impulses

BACKGROUND

In our previous investigations we showed that electrical impulses (EI) can prevent the development of atherosclerosis if they began simultaneously with high cholesterol diet (HCD) or in the early stages of atherosclerosis (after three weeks of HCD only). In this investigation we demonstrated the slow progression or elimination of atherosclerosis by low-frequency EI in case of moderate atherosclerosis (after eight weeks of HCD).

METHODS

Series I rabbits (control group) were fed HCD for eight weeks. Series II rabbits were fed HCD for eight weeks and were then switched to normal diet for eight weeks (no EI). Series III rabbits were fed HCD for eight weeks and then switched to a normal diet with simultaneous EI (applied near the abdominal aorta) for eight weeks (3 V, 30 single impulses per minute, 24 hours/day). After euthanization, the level of atherosclerosis, percentage of surface area involved in the atherosclerosis process, and an atherosclerosis score were calculated in the aortic arch, thoracic and abdominal aorta.

RESULTS

Statistically significant differences were seen in the level of atherosclerosis in the abdominal aorta between series III animals (0.4 +/- 0.2) and the other two groups: 1.5 +/- 0.4 in series I (HCD only), 1.2 +/- 0.3 in series II (HCD then normal diet). Gross examination of the surface also revealed statistically significant differences (p < 0.05) in the percentage of atherosclerosis between the control series I (30.1 +/- 4.1%) and series II (21.3 +/- 3.6%), compared with series III (5.5 +/- 5.4%). In addition, the atherosclerosis score was also significantly different: 45.8 +/- 3.9 in series I, 25.2 +/- 6.9 in series II, and 2.2 +/- 2.0 in series III (p < 0.05).

CONCLUSION

Our study showed that, when applied near the abdominal aorta, low-frequency electrical impulses decrease atherosclerotic deposition in the abdominal aorta.

Pathologic and histologic results of electrical impulses in a rabbit model of atherosclerosis: 24-hour versus 8-hour regimen

OBJECTIVE

Low frequency electrical impulses (EIs) reduce new atherosclerotic plaque formation in previously diseased arteries and may reverse the extent of previous pathologic damage in these structures.

METHODS

A pacemaker was implanted on the left side of rabbit abdominal aortas, and an electrode was placed close to the other side of the aorta in the psoas major muscle. For the induction of atherosclerosis, the rabbits were placed on a high cholesterol diet (HCD) for 11 weeks. No EIs were applied to the control series I. In the experimental series, the rabbits were fed an HCD for 3 weeks, after which EIs were applied simultaneously with an HCD for 8 additional weeks (3V, 30 contractions per minute). Experimental series II had 24-hour/day EIs, and series III had 8-hour/day EIs.

RESULTS

The closer to the area where the EIs were applied, the more local severity increased (atherosclerosis level and surface area). In the control series, the severity of atherosclerosis in the lower aorta assessed with an arbitrary grading system was 1.75 +/- 0.5 (versus 1.5 +/- 0.57 with 8-hour/day EIs and 0.5 +/- 0.3 with 24-hour/day EIs). The involved surface area was 32.5% +/- 9.5% (versus 1.0% +/- 0.8% with 8-hour/day EIs and 0.75% +/- 0.95% with 24-hour/day EIs).

CONCLUSION

Both 24-hour/day and 8-hour/day EIs applied close to the abdominal aorta decreased the severity of atherosclerosis in rabbits placed on a HCD, but 24-hour/day EIs decreased the severity more extensively.