Visualized identification of the maximal surgical delay effect in a rat flap model

Electrical stimulation promoting the angiogenesis in diabetic rat perforator flap through attenuating oxidative stress-mediated inflammation and apoptosis

Background

Skin flap transplantation is one of the effective methods to treat the diabetes-related foot ulceration, but the intrinsic damage to vessels in diabetes mellitus (DM) leads to the necrosis of skin flaps. Therefore, the discovery of a non-invasive and effective approach for promoting the survival of flaps is of the utmost importance. Electrical stimulation (ES) promotes angiogenesis and increases the proliferation, migration, and elongation of endothelial cells, thus being a potential effective method to improve flap survival.

Objective

The purpose of this study was to elucidate the mechanism used by ES to effectively restore the impaired function of endothelial cells caused by diabetes.

Methods

A total of 79 adult male Sprague-Dawley rats were used in this study. Gene and protein expression was assessed by PCR and western blotting, respectively. Immunohistochemistry and hematoxylin-eosin staining were performed to evaluate the morphology and density of the microvessels in the flap.

Results

The optimal duration for preconditioning the flap with ES was 7 days. The flap survival area percentage and microvessels density in the DMES group were markedly increased compared to the DM group. VEGF, MMP2, and MMP9 protein expression was significantly upregulated. ROS intensity was significantly decreased and GSH concentration was increased. The expression of IL-1β, MCP‑1, cleaved caspase-3, and Bax were downregulated in the DMES group, while TGF-β expression was upregulated.

Conclusions

ES improves the angiogenesis in diabetic ischemic skin flaps by attenuating oxidative stress-mediated inflammation and apoptosis, eventually increasing their viability.

The Effects of Angiosome Morphology on Choke Vessels and Flap Necrosis in a Rat Multiterritory Perforator Flap

BACKGROUND

Although the angiosome concept has been proposed for a long time, very few studies have been done on its morphology. Our study investigated the effects of angiosome morphology on choke vessels and flap necrosis in a rat multiterritory perforator flap.

METHODS

Seventy-two male Sprague-Dawley rats were randomly divided into 3 groups (n = 24/group). The flap contained the right iliolumbar, posterior intercostal, and thoracodorsal angiosomes (TDAVs), termed angiosomes I, II, and III, respectively. Only the posterior intercostal artery and iliolumbar vein were preserved in group 1, whereas only the posterior intercostal artery and vein were preserved in group 2, and only the posterior intercostal artery and thoracodorsal vein were preserved in group 3. Distances from angiosome II to angiosome I (II-I), angiosome II to angiosome III (II-III), angiosome I to the caudal side of the flap (I-caudal), and angiosome III to the cranial side of the flap (III-cranial) were measured. Arteriography, flap necrosis, average microvascular density, and vascular endothelial growth factor expression were evaluated.

RESULTS

The II-I distance was significantly greater than that of II-III (3.853 ± 0.488 versus 3.274 ± 0.433 cm, P = 0.012), whereas the distance of I-caudal resembled that of III-cranial (1.062 ± 0.237 versus 0.979 ± 0.236 cm, P = 0.442). The iliolumbar and posterior intercostal angiosomes were multidirectional, whereas the TDAV was craniocaudal and unidirectional. Seven days after the operation, the choke arteries had transformed into true anastomotic arteries. Flap necrosis was lowest in group 3, followed by group 2, and highest in group 1 (10.5% ± 2.4% versus 18.3% ± 3.5% versus 25.5% ± 4.6%, P < 0.01), whereas group 3 showed the highest microvascular density and vascular endothelial growth factor expression, in contrast to groups 2 and 1, with the lowest.

CONCLUSIONS

The choke vessel adjacent to the craniocaudal and unidirectional TDAV significantly blocked venous return. Increasing venous return may reduce the necrosis.

Correlation of vascular change with TRPV1, TRPV4, and TRPA1 in a rat model of inferior gluteal artery perforator flap

Maximum survival area after perforator flap elevation is mainly achieved through vasodilation and angiogenesis, and endothelial Ca²⁺ signals play a pivotal role in both of them. Transient receptor potential (TRP) channels modulate many endothelial cell functions via mediating the extracellular Ca²⁺ entry. This study aims to investigate the correlation of TRPV4, TRPV1, and TRPA1 with vascular change after the inferior gluteal artery perforator flap elevation. A total of 50 adult male SD rats were used in this study. Ten rats were used in the part one to assess the flap viability on postoperative day 7. Twenty rats were used in the part two to evaluate blood flow change after flap elevation. The correlation of vascular change with TRPV1, TRPV4, and TRPA1 protein changes was investigated in 20 rats in the part three. The mean flap survival area percentage was 55 ± 5.7%. Blood flow in the overall flap and Zone II after the flap elevation markedly increased from the postoperative day 3. The most marked change of the vasodilation occurred on Days 3 and 5 after flap elevation. The angiogenesis occurred on Day 5 after flap elevation and the microvessel density peaked also on Day 5. Moreover, TRPA1 expression showed a trend towards continuous reduction over time. The expression of TRPV1 and TRPV4 reached the peak value on Day 3. The endothelial NO synthase expression showed an increasing trend at first, followed by a reduction over time, while VEGF expression reached the peak value on Day 3. The vascular changes after flap elevation might be associated with the changes in TRPV4, TRPV1, and TRPA1.

Which one is better for multi-territory perforator flap survival, central perforator artery or central perforator vein?

BACKGROUND

The survival of multi-territory perforator flap is associated with the position of the perforators. This study aimed to explore whether use of the central perforator artery or vein was better for flap survival.

METHODS

75 male Sprague-Dawley rats were randomly divided into three groups (n=25 per group). The flap contained the right and left iliolumbar, left posterior intercostal, and left thoracodorsal angiosomes, termed angiosomes Ⅰ to Ⅳ, respectively. The anastomosis between angiosomes Ⅱ and Ⅲ was termed choke 2. In experimental group 2, only the right iliolumbar vein and the left iliolumbar artery were preserved; in experimental group 1, only the right iliolumbar artery and the left iliolumbar vein were preserved; and in the control group, only the right iliolumbar artery and vein were preserved. On day-7 after the operation, the flap arteriography, intraluminal diameter, average microvascular density, vascular endothelial growth factor (VEGF) expression and flap survival were compared among groups. Moreover, the percentages of the angiosomes were measured.

RESULTS

The dilation of the choke 2 artery was most pronounced in experimental group 2, followed by experimental group 1, and, finally, the control group (p<0.05). Similar results regarding average microvascular density, VEGF expression, and survival rate were found among the three groups. The percentages of angiosomes Ⅰ to Ⅳ were 23.1%, 23.0±3.1%, 23.0±1.9%, and 31.0±3.1%, respectively.

CONCLUSIONS

Compared with the central perforator vein, the central perforator artery was more beneficial in enhancing flap survival. A multi-territory perforator flap with the central perforator artery could capture 3 angiosomes safely.

Intra- and Early Postoperative Evaluation of Malperfused Areas in an Irradiated Random Pattern Skin Flap Model Using Indocyanine Green Angiography and Near-Infrared Reflectance-Based Imaging and Infrared Thermography

Background: Assessment of tissue perfusion after irradiation of random pattern flaps still remains a challenge. Methods: Twenty-five rats received harvesting of bilateral random pattern fasciocutaneous flaps. Group 1 served as nonirradiated control group. The right flaps of the groups 2–5 were irradiated with 20 Gy postoperatively (group 2), 3 × 12 Gy postoperatively (group 3), 20 Gy preoperatively (group 4) and 3 × 12 Gy preoperatively (group 5). Imaging with infrared thermography, indocyanine green angiography and near-infrared reflectance-based imaging were performed to detect necrotic areas of the flaps. Results: Analysis of the percentage of the necrotic area of the irradiated flaps showed a statistically significant increase from day 1 to 14 only in group 5 (p < 0.05). Indocyanine green angiography showed no differences (p > 0.05) of the percentage of the nonperfused area between all days in group 1 and 3, but a decrease in group 2 in both the left and the right flaps. Infrared thermography and near-infrared reflectance-based imaging did not show evaluable differences. Conclusion: Indocyanine green angiography is more precise in prediction of necrotic areas in random pattern skin flaps when compared to hyperspectral imaging, thermography or clinical impression. Preoperative fractional irradiation with a lower individual dose but a higher total dose has a more negative impact on flap perfusion compared to higher single stage irradiation.

Non-invasive physical therapy as salvage measure for ischemic skin flap: A literature review

This review focuses on the available evidence regarding the molecular mechanisms and treatment potential of several non-surgical physical therapies for managing flap ischemia to propose a non-invasive, economical, and simple treatment to improve flap survival. A review of the literature was conducted on the topics of various non-invasive methods for the treatment of ischemic necrosis of the distal end of the flap between 1988 and 2019. A total of 52 published studies were reviewed on the applications of hyperbaric oxygen therapy, electrical stimulation therapy, heat stress pretreatment, phototherapy, and vibration therapy to manage skin flap necrosis. The underlying molecular mechanisms of these physical therapies on revitalizing the dying skin flaps were discussed and preliminary clinical uses of these therapies to salvage the necrotic skin flaps were pooled and summarized for clarifying the safety and feasibility of these methods. Various physical therapy regimens have been ushered to manage necrotic development in cutaneous flaps. With the refinement of these new technologies and enhancement of related basic science research on vascular revitalization, the prevention and treatment of flap ischemia will enter a new era.

Effect of acupuncture on neurovascular units after cerebral infarction in rats through PI3K/AKT signaling pathway

OBJECTIVE

To study the effect of acupuncture on neurovascular units after cerebral infarction (CI) in rats through the phosphatidylinositol 3-hydroxy kinase/protein kinase B (PI3K/AKT) signaling pathway.

METHODS

A total of 36 Sprague-Dawley rats were randomly divided into sham group (n = 12), model group (n = 12) and acupuncture group (n = 12). The external carotid artery was only exposed in model group, while the post-CI ischemia-reperfusion model was established using the suture method in the other 2 groups. After modeling, the rats in sham group and model group were fixed and sampled, while those in acupuncture group were treated with acupuncture intervention for 2 weeks and sampled. The neurological deficits of rats were evaluated using the Zea-Longa score, and the spatial learning and memory of rats were detected via water maze test. Moreover, the expressions of vascular endothelial growth factor (VEGF), growth associated protein-43 (GAP-43) and synuclein (SYN) in brain tissues were detected via immunohistochemistry, and the relative protein expressions of PI3K p85, PI3K p110 and p-AKT were detected via Western blotting. The messenger ribonucleic acid (mRNA) expressions of VEGF, GAP-43 and SYN were detected via quantitative polymerase chain reaction (qPCR).

RESULTS

The Zea-Longa score was significantly increased in model group and acupuncture group compared with that in sham group (p < 0.05), while it significantly declined in acupuncture group compared with that in model group (p < 0.05). The escape latency was significantly prolonged and the times of crossing platform were significantly reduced in model group and acupuncture group compared with those in sham group (p < 0.05), while the escape latency was significantly shortened and the times of crossing platform were significantly increased in acupuncture group compared with those in model group (p < 0.05). The positive expressions of VEGF, GAP-43 and SYN were obviously increased in model group and acupuncture group compared with those in sham group (p < 0.05), while they were obviously increased in acupuncture group compared with those in model group (p < 0.05). Besides, model group and acupuncture group had significantly higher relative protein expressions of PI3K p85, PI3K p110 and p-AKT than sham group (p < 0.05), while acupuncture group also had significantly higher relative protein expressions of PI3K p85, PI3K p110 and p-AKT than model group (p < 0.05). The relative mRNA expressions of VEGF, GAP-43 and SYN were remarkably increased in model group and acupuncture group compared with those in sham group (p < 0.05), while they were remarkably increased in acupuncture group compared with those in model group (p < 0.05).

CONCLUSION

Acupuncture promotes the repair of neurovascular units after CI in rats through activating the PI3K/AKT signaling pathway, thereby exerting a protective effect on neurovascular units.

Effects of arterial blood supply and venous return on multi-territory perforator flap survival

This study aimed to design arterial ischemic and venous congested areas on the same multi-territory perforator flap, assessing the effects of arterial blood supply and venous return on flap survival. Totally 68 rats were randomly divided into the experimental (Exp) and control (Con) groups. In the Exp group, flaps were based on left superficial epigastric artery and right superficial epigastric vein. In the Con group, flaps were based on the left superficial epigastric artery and vein. Immediate postoperative ink-gelatin angiography, epidermal metabolite levels detection, tissue edema measurement, survival rate evaluation in half of the flaps and average microvessel density assessment were performed. Blood in the Exp group flowed through most angiosomes, but only flowed around pedicled vessels in the Con group; metabolite levels of left halves in the Con and Exp groups were comparable with those of right halves. Angiosomes with high water contents occurred in the Exp group. Survival rates of left halves in the Con and Exp groups were higher than those of right halves, and more microvessels were found in the left ventral areas of both groups compared with the right ventral area in the Exp group. These findings revealed that on the same multi-territory perforator flap, arterial blood supply, affected by venous return, is a prerequisite for flap survival.