Bilirubin provides perforator flap protection from ischaemia-reperfusion injury in a rat model: a preliminary result

Tetrahydropalmatine: Orchestrating survival - Regulating autophagy and apoptosis via the PI3K/AKT/mTOR pathway in perforator flaps

BACKGROUND

Introduced in clinical practice in 1989, perforator flaps are vital for tissue defect repair, but they are challenged by distal necrosis. Tetrahydropalmatine (THP) from celandine is renowned for its anti-inflammatory and analgesic effects. This study investigates THP's use in perforator flaps.

METHODS

Thirty rats were divided into a control group and four THP concentration groups, while seventy-eight rats were categorized as control, THP, THP combined with rapamycin (RAP), and RAP alone. We created 11 cm by 2.5 cm multi-regional perforator flaps on rat backs, assessing survival blood flow and extracting skin flap tissue for autophagy, oxidative stress, apoptosis, and angiogenesis markers.

RESULTS

The THP group exhibited significantly reduced distal necrosis, increased blood flow density, and survival area on the seventh day compared to controls. Immunohistochemistry and Western blot results demonstrated improved anti-oxidative stress and angiogenesis markers, along with decreased autophagy and apoptosis indicators. Combining THP with RAP diminished flap survival compared to THP alone. This was supported by protein expression changes in the PI3K-AKT-mTOR pathway.

CONCLUSION

THP enhances flap survival by modulating autophagy, reducing tissue edema, promoting angiogenesis, and mitigating apoptosis and oxidative stress. THP offers a potential strategy for enhancing multi-regional perforator flap survival through the PI3K/AKT/mTOR pathway. These findings highlight THP's promise in combatting perforator flap necrosis, uncovering a novel mechanism for its impact on flap survival.

Distal Arterialized Venous Supercharging Improves Perfusion and Survival in an Extended Dorsal Three-Perforasome Perforator Flap Rat Model

BACKGROUND

Perforator flaps are commonly applied for a variety of skin defects. Many strategies (e.g., hyperbaric oxygen and preconditioning) have been investigated to improve flap survival, but a postoperative 2.03 to 18.2 percent flap necrosis frequency remains a major complication. The authors hypothesized that a distal arterialized venous supercharged (DAVS) flap procedure might improve perfusion and survival in an extended three-perforasome perforator flap rat model and rescue flap ischemia intraoperatively.

METHODS

One hundred twenty male Sprague-Dawley rats (200 to 300 g) were divided into the thoracodorsal artery (TDA) flap group and the DAVS flap group (n = 60 per group). An approximately 11 × 2.5-cm2 flap based on the TDA perforasome was designed in the TDA flap. A DAVS flap was designed based on the TDA flap and supercharged by anastomosing the rat caudal artery with the deep circumflex iliac vein. At postoperative times 1, 3, 6, and 12 hours and 1, 3, 5, and 7 days, perfusion and angiography were compared. On day 7, flap viability and angiogenesis were assessed using histology and Western blotting.

RESULTS

The DAVS flap showed a higher survival rate compared with the TDA flap (100 percent versus 81.93 ± 5.38 percent; p < 0.001). All blood flow ratios of deep circumflex iliac artery to TDA perforasome and of choke zone II to choke zone I were higher in the DAVS flap (all p < 0.05). Angiography qualitatively revealed that choke vessels in choke zone II dilated earlier and extensively in the DAVS flap group. CD34+ vessels (68.66 ± 12.53/mm2 versus 36.82 ± 8.99/mm2; p < 0.001) and vascular endothelial growth factor protein level (0.22 ± 0.03 versus 0.11 ± 0.03; p < 0.001) were significantly increased in the DAVS flap group.

CONCLUSIONS

The DAVS procedure improves three-perforasome perforator flap survival and can be used for rescuing flap ischemia intraoperatively. Further study is needed before possible clinical adoption for reconstructive operations.

The Effect of Botulinum Toxin on Flap Viability of the Posterior Thigh Perforator Flap in Rats

BACKGROUND

The use of perforator propeller flaps in lower limb reconstruction has increased recently. Many pharmacological agents are used to increase flap viability. Botulinum toxin has been used in various types of flaps in the literature. However, there is no study regarding the use of botulinum toxin in the lower limb propeller flaps. This study investigates the effect of botulinum toxin administration on flap survival for lower limb propeller flap in rats.

MATERIALS AND METHODS

The study included 20 male Wistar albino rats, divided into two groups with a flap rotation of 90° in group 1 and 180° in group 2. In both groups, botulinum toxin was administered to the right thigh and a physiological saline solution was applied to the left thigh. Five days later, flaps were elevated over the posterior aspect of the right and left thighs and inset after 90° and 180° rotation was performed. Histopathological, immunohistochemical, and necrosis area analyses were performed.

RESULTS

Necrosis area, edema, polymorphonuclear leukocyte infiltration, and necrosis were found to be higher on the left side of the groups, whereas epidermal thickness, collagen density, vascularization, and hair root density were found to be higher on the right side of the groups. No significant difference was found between the right posterior thighs in either group on any parameter other than vascularization. Histopathologically and immunochemically statistically significant differences were found between the two groups.

CONCLUSIONS

The present study found that botulinum toxin increases flap viability in lower limb perforator-based propeller flaps.

Two Faces of Heme Catabolic Pathway in Newborns: A Potential Role of Bilirubin and Carbon Monoxide in Neonatal Inflammatory Diseases

In an infant's body, all the systems undergo significant changes in order to adapt to the new, extrauterine environment and challenges which it poses. Fragile homeostasis can be easily disrupted as the defensive mechanisms are yet imperfect. The activity of antioxidant enzymes, i.e., superoxide dismutase, catalase, and glutathione peroxidase, is low; therefore, neonates are especially vulnerable to oxidative stress. Free radical burden significantly contributes to neonatal illnesses such as sepsis, retinopathy of premature, necrotizing enterocolitis, bronchopulmonary dysplasia, or leukomalacia. However, newborns have an important ally-an inducible heme oxygenase-1 (HO-1) which expression rises rapidly in response to stress stimuli. HO-1 activity leads to production of carbon monoxide (CO), free iron ion, and biliverdin; the latter is promptly reduced to bilirubin. Although CO and bilirubin used to be considered noxious by-products, new interesting properties of those compounds are being revealed. Bilirubin proved to be an efficient free radicals scavenger and modulator of immune responses. CO affects a vast range of processes such as vasodilatation, platelet aggregation, and inflammatory reactions. Recently, developed nanoparticles consisting of PEGylated bilirubin as well as several kinds of molecules releasing CO have been successfully tested on animal models of inflammatory diseases. This paper focuses on the role of heme metabolites and their potential utility in prevention and treatment of neonatal diseases.

Hydroxysafflor yellow A promotes multiterritory perforating flap survival: an experimental study

The use of perforator flaps is a common surgical technique in wound repair. However, the area surrounding the multiterritory perforating flap often becomes necrotic due to ischemia. Hydroxysafflor yellow A (HSYA), a traditional Chinese medicine extracted from edible safflower, can be used medicinally to promote angiogenesis, inhibit apoptosis, and alleviate oxidative stress and other biological activities. Here, we investigated the effect of HSYA on perforator flap survival and its potential mechanism. Our results demonstrate that HSYA significantly improves the survival area of perforator flaps, increases blood supply, reduces tissue edema, and increases mean vascular density. HSYA treatment promotes angiogenesis and inhibits oxidative stress, apoptosis, and autophagy in perforator flaps, suggesting many potential mechanisms for flap survival.

Effect of Botulinum Toxin-A Injected to Muscle Tissue on Perfusion and Survival of Fasciocutaneous Single Perforator-pedicled Propeller Flap in Rats

Background:

In plastic surgery practice, fasciocutaneous single-perforator-pedicled propeller flap is a preferred procedure; however, its survival rate is below than expected, especially in flaps with a big rotation arc. When botulinum toxin-A is injected into the muscle tissue that the perforator pedicle is arisen, the tonus of pertinent muscle can reduce and the blood flow of its perforator pedicle can increase. Therefore this procedure can improve the survival rate of single-perforator-pedicled propeller flap.

Aims:

To evaluate the effect of botulinum toxin-A injected with ultrasonographic guidance into the muscle tissue that the perforator pedicle is arisen from one month ago on the perfusion of flap scintigraphically and the survival rate of single-perforator-pedicled propeller flap in a rat model.

Study Design:

Animal experiment.

Methods:

Three study groups were receiving botulinum toxin-A (16 IU-0.4 mL), normal saline (0.4 mL), and no study drug one month ago before flap surgery. Injections were performed under ultrasonography guidance. Flaps were elevated fasciocutaneously over the right 2nd perforator pedicle, under the corneous, with a surgical loupe and microsurgery tool and were rotated clockwise 180°. Then the scintigraphic measurements were obtained after flap elevations in the study groups, including the whole-body and flap perfusions in the study rats. The involvement rate presents the ratio of flap perfusion to whole-body perfusion. Flaps were sutured back to the abdominal wall at the latest twisting angles. With standard photographs taken in all the groups on day 8 after the operation, whole and necrotic flap areas were calculated.

Results:

Scintigraphically the involvement rate (the ratio of flap perfusion to whole-body perfusion) of the flaps in the botulinum toxin-A group were found significantly higher than those in the other groups (p<0.05). The area of a flap in the botulinum toxin-A group on day 8 post flap suturing was found to be significantly higher than those in the other groups (p<0.05). The area of a necrosis and the percentage of necrosis on day 8 post flap suturing in the botulinum toxin-A group was found significantly lower than those of the sham and null groups (p<0.05).

Conclusion:

In a rat model, if with the ultrasonographic guidance, botulinum toxin-A is injected to the muscle which perforator of the prospective single-perforator-pedicled propeller flap originated and flap surgery is performed one month later after this injection, the perfusion of single-perforator-pedicled propeller flap increases scintigraphically and this improves flap survival and reduces its necrosis.