Micro-RNA-Regulated Proangiogenic Signaling in Arteriovenous Loops in Patients with Combined Vascular and Soft-Tissue Reconstructions: Revisiting the Nutrient Flap Concept

Free peroneal artery perforator flap for reconstruction of traumatic limb soft tissue defects: A retrospective case series study

BACKGROUND

The free peroneal artery perforator (FPAP) flap is used for soft tissue defects after burns and trauma. However, the use of FPAP flaps to repair limb soft tissue defects for immediate reconstruction was rarely reported previously. Therefore, the purpose of this report is to evaluate free peroneal artery perforator flap to reconstruct traumatic limb soft tissue defects for immediate reconstruction.

PATIENTS AND METHODS

A total of 25 cases of limb soft tissue defects undergoing immediate reconstruction of FPAP flap transfer were retrospectively evaluated from January 2019 to June 2019 in our institute. The locations of defects included the palm (10 cases), finger (5 cases), foot (7 cases), ankle (2 cases) and wrist (1 case). The sizes of defect varied from 3 × 2 cm to 15 × 7 cm (54.1 cm2 in average). Flaps were harvested based on the peroneal perforator vessels, initially marked using hand-held Doppler.

RESULTS

Average size of harvested flap was 9.7 × 6.2 cm (ranging from 3.5 × 2 cm to 16 × 8 cm). All perforators were harvested from the peroneal artery and the arterial diameter ranged from 0.8 to 1.7 mm. The average pedicle length was 3.04 cm (range, 1.85-4.75 cm). Five vascular thrombosis were found including three cases of arterial thrombosis and two cases of venous thrombosis which were successfully salvaged by re-operation and vein graft. Satisfying functional outcome and acceptable appearance were achieved at 6 months or longer after surgery (range, 6-15 months, 12 months in average). All flaps survived at the end-point.

CONCLUSIONS

The FPAP flap is a reliable and thin fasciocutaneous flap, which can be used for repairing limb soft tissue defects. The FPAP flap can be used for covering defects with various appearances, locations, and sizes.

Prefabrication-a Vascularized Skin Flap Using an Arteriovenous LoopPrefabricated Flap With Arteriovenous Loop: An Experimental Study in Minipigs

BACKGROUND

Arteriovenous loops have a high potency to induce angiogenesis and are promising to solve the problem of scarce implanted pedicle sources and insufficient neovascularization in flap prefabrication. But there is a lack of large animal experiments to support their clinical application. Therefore, we aimed to explore the feasibility of prefabricating large flaps based on arteriovenous loops in pigs.

METHODS

Five minipigs were used. In the experimental group, a 10-cm-long ear vein graft was microanastomosed with the saphenous artery and vein to form an arteriovenous loop and implanted under the medial thigh flap. A month later, a 10×10 cm prefabricated flap pedicled with the arteriovenous loop was elevated and sutured in situ. In the control group, a 10×10 cm flap with no vascular pedicle was elevated completely and sutured in situ in the same position. The patency of the arteriovenous loop was evaluated by angiography 30 days after implantation, and the viability of flaps was assessed by macroscopic analysis 10 days after elevation. Three animals received arteriovenous loop flaps unilaterally and no-pedicle flaps unilaterally. Two animals received arteriovenous loop flaps bilaterally.

RESULTS

In the experimental group, no thrombi were exhibited in any arteriovenous loop. All 7 prefabricated flaps survived uneventfully. In the control group, 3 flaps were completely necrotic.

CONCLUSION

The arteriovenous loops with long interpositional venous grafts can be used as vascular pedicles to prefabricated large area and well-vascularized flaps. This approach can greatly expand the application of flap prefabrication.

Enrichment of Nanofiber Hydrogel Composite with Fractionated Fat Promotes Regenerative Macrophage Polarization and Vascularization for Soft-Tissue Engineering

BACKGROUND

Fractionated fat has been shown to promote dermal regeneration; however, the use of fat grafting for reconstruction of soft-tissue defects is limited because of volume loss over time. The authors have developed a novel approach for engineering of vascularized soft tissue using an injectable nanofiber hydrogel composite enriched with fractionated fat.

METHODS

Fractionated fat was generated by emulsification of groin fat pads from rats and mixed in a 3:1 ratio with nanofiber hydrogel composite (nanofiber hydrogel composite with fractionated fat). Nanofiber hydrogel composite with fractionated fat or nanofiber hydrogel composite alone was placed into isolation chambers together with arteriovenous loops, which were subcutaneously implanted into the groin of rats (n = 8 per group). After 21 days, animals were euthanized and systemically perfused with ink, and tissue was explanted for histologic analysis. Immunofluorescent staining and confocal laser scanning microscopy were used to quantify CD34+ progenitor cell and macrophage subpopulations.

RESULTS

Nanofiber hydrogel composite with fractionated fat tissue maintained its shape without shrinking and showed a significantly stronger functional vascularization compared to composite alone after 21 days of implantation (mean vessel count, 833.5 ± 206.1 versus 296.5 ± 114.1; p = 0.04). Tissue heterogeneity and cell count were greater in composite with fractionated fat (mean cell count, 49,707 ± 18,491 versus 9263 ± 3790; p = 0.005), with a significantly higher number of progenitor cells and regenerative CD163+ macrophages compared to composite alone.

CONCLUSIONS

Fractionated fat-enriched nanofiber hydrogel composite transforms into highly vascularized soft tissue over 21 days without signs of shrinking and promotes macrophage polarization toward regenerative phenotypes. Enrichment of injectable nanofiber hydrogel composite with fractionated fat represents a promising approach for durable reconstruction of soft-tissue defects.

CLINICAL RELEVANCE STATEMENT

The authors' approach for tissue engineering may ultimately lay the groundwork for clinically relevant applications with the goal of generating large volumes of vascularized soft tissue for defect reconstruction without donor site morbidity.

MicroRNA-29b/c-3p Indicate Advanced Liver Fibrosis/Cirrhosis in Univentricular Heart Patients With and Without Fontan Palliation

Aim: The present study aims to identify those microRNAs (miRNAs) in patients with univentricular heart (UVH) disease with and without Fontan palliation that may be associated with advanced liver fibrosis/cirrhosis. Materials and Methods: SurePrint™ 8 × 60K Human v21 miRNA arrays were used to determine the miRNA abundance profiles in the blood of 48 UVH patients with and without Fontan palliation and 32 matched healthy controls. The abundance levels of selected miRNAs have been validated by quantitative reverse transcription-polymerase chain reaction (RT-qPCR). Results: According to microarray analysis, 50 miRNAs were found to be significantly abundant in UVH patients of which miR-29b-3p and miR-29c-3p were significantly related to the model of end-stage liver disease (MELD)-Albumin and albumin-bilirubin (ALBI) score representing advanced liver fibrosis/cirrhosis. Relative expression levels of both miRNAs were significantly higher in patients with a higher collapsibility index representing venous hepatic congestion, a higher MELD-Albumin or ALBI score and incomplete or no Fontan palliation. In the logistic regression analysis, a MELD-Albumin score ≥ 11 or ALBI score > -2.6 were best predicted by total bilirubin (OR 6.630, P = 0.016), albumin (OR 0.424, P = 0.026), and miR-29c-3p (OR 33.060, P = 0.047). After adjustment to the status of Fontan palliation, however, no statistical significance of these parameters was found thus underlining the importance of palliation status on progression of liver fibrosis/ cirrhosis in UVH patients. Conclusions: In UVH patients with and without Fontan palliation, miR-29b-3p and miR-29c-3p seem to be markers of advanced liver fibrosis/cirrhosis and thus may be used in the risk assessment of these patients.

A multivariable miRNA signature delineates the systemic hemodynamic impact of arteriovenous shunt placement in a pilot study

Arteriovenous (AV) fistulas for hemodialysis can lead to cardiac volume loading and increased serum brain natriuretic peptide (BNP) levels. Whether short-term AV loop placement in patients undergoing microsurgery has an impact on cardiac biomarkers and circulating microRNAs (miRNAs), potentially indicating an increased hemodynamic risk, remains elusive. Fifteen patients underwent AV loop placement with delayed free flap anastomosis for microsurgical reconstructions of lower extremity soft-tissue defects. N-terminal pro-BNP (NT-proBNP), copeptin (CT-proAVP), and miRNA expression profiles were determined in the peripheral blood before and after AV loop placement. MiRNA expression in the blood was correlated with miRNA expression from AV loop vascular tissue. Serum NT-proBNP and copeptin levels exceeded the upper reference limit after AV loop placement, with an especially strong NT-proBNP increase in patients with preexistent cardiac diseases. A miRNA signature of 4 up-regulated (miR-3198, miR-3127-5p, miR-1305, miR-1288-3p) and 2 down-regulated miRNAs (miR30a-5p, miR-145-5p) which are related to cardiovascular physiology, showed a significant systemic deregulation in blood and venous tissue after AV loop placement. AV loop placement causes serum elevations of NT-proBNP, copeptin as well as specific circulating miRNAs, indicating a potentially increased hemodynamic risk for patients with cardiovascular comorbidities, if free flap anastomosis is delayed.

Tissue Engineering of Axially Vascularized Soft-Tissue Flaps with a Poly-(ɛ-Caprolactone) Nanofiber-Hydrogel Composite

Objective: To develop a novel approach for tissue engineering of soft-tissue flaps suitable for free microsurgical transfer, using an injectable nanofiber hydrogel composite (NHC) vascularized by an arteriovenous (AV) loop. Approach: A rat AV loop model was used for tissue engineering of vascularized soft-tissue flaps. NHC or collagen-elastin (CE) scaffolds were implanted into isolation chambers together with an AV loop and explanted after 15 days. Saphenous veins were implanted into the scaffolds as controls. Neoangiogenesis, ultrastructure, and protein expression of SYNJ2BP, EPHA2, and FOXC1 were analyzed by immunohistochemistry and compared between the groups. Rheological properties were compared between the two scaffolds and native human adipose tissue. Results: A functional neovascularization was evident in NHC flaps with its amount being comparable with CE flaps. Scanning electron microscopy revealed a strong mononuclear cell infiltration along the nanofibers in NHC flaps and a trend toward higher fiber alignment compared with CE flaps. SYNJ2BP and EPHA2 expression in endothelial cells (ECs) was lower in NHC flaps compared with CE flaps, whereas FOXC1 expression was increased in NHC flaps. Compared with the stiffer CE flaps, the NHC flaps showed similar rheological properties to native human adipose tissue. Innovation: This is the first study to demonstrate the feasibility of tissue engineering of soft-tissue flaps with similar rheological properties as human fat, suitable for microsurgical transfer using an injectable nanofiber hydrogel composite. Conclusions: The injectable NHC scaffold is suitable for tissue engineering of axially vascularized soft-tissue flaps with a solid neovascularization, strong cellular infiltration, and biomechanical properties similar to human fat. Our data indicate that SYNJ2BP, EPHA2, and FOXC1 are involved in AV loop-associated angiogenesis and that the scaffold material has an impact on protein expression in ECs.

Insights from circulating microRNAs in cardiovascular entities in turner syndrome patients

Background

Turner syndrome (TS) is a chromosomal disorder, in which a female is partially or entirely missing one of the two X chromosomes, with a prevalence of 1:2500 live female births. The present study aims to identify a circulating microRNA (miRNA) signature for TS patients with and without congenital heart disease (CHD).

Methods

Microarray platform interrogating 2549 miRNAs were used to detect the miRNA abundance levels in the blood of 33 TS patients and 14 age-matched healthy volunteer controls (HVs). The differentially abundant miRNAs between the two groups were further validated by RT-qPCR.

Results

We identified 60 differentially abundant miRNA in the blood of TS patients compared to HVs, from which, 41 and 19 miRNAs showed a higher and a lower abundance levels in TS patients compared to HVs, respectively. RT-qPCR confirmed the significantly higher abundance levels of eight miRNAs namely miR-374b-5p, miR-199a-5p, miR-340-3p, miR-125b-5p, miR-30e-3p, miR-126-3p, miR-5695, and miR-26b-5p in TS patients as compared with the HVs. The abundance level of miR-5695 was higher in TS patients displaying CHD as compared to TS patients without CHD (p = 0.0265; log2-fold change 1.99); whereas, the abundance level of miR-126-3p was lower in TS patients with congenital aortic valve disease (AVD) compared to TS patients without BAV (p = 0.0139, log2-fold change 1.52). The clinical feature statistics revealed that miR-126-3p had a significant correlation with sinotubular junction Z-score (r = 0.42; p = 0.0154).

Conclusion

The identified circulating miRNAs signature for TS patients with manifestations associated with cardiovascular diseases provide new insights into the molecular mechanism of TS that may guide the development of novel diagnostic approaches.

Increased angiogenesis by the rotational muscle flap is crucial for nerve regeneration

Background

The gold standard surgical treatment of nerve injury includes direct repair, nerve graft, and neurolysis. The underlying effects (either beneficial or detrimental) of angiogenesis during nerve regeneration by rotational muscle flap have not yet determined. We assess the neurological outcome and angiogenesis of nerve injury following a rotational muscle flap.

Methods

We retrospectively analyzed the outcome of the patients with severe radial nerve injury by neurolysis and rotational muscle flap; we also mimicked the clinical situation by nerve crush followed by rotational muscle flap in animals to assess associated angiogenesis factor expression.

Results

Twenty-three out of 25 (92%) cases of severe radial nerve injury underwent neurolysis assisted by muscle flap rotation and eventually reached their preinjury neurological outcome. In the animal study, both FITC–dextran and Dil infusion showed a remarkably increased vascular structure in the crushed nerve integrated by the muscle flap and abolished by Avastin injection. The rotational muscle flap significantly increased angiogenesis factor expression, and this was attenuated by Avastin injection. The increased angiogenesis factor expression paralleled the improvement seen in neurobehavioral and electrophysiological studies as well as the significant expression of nerve regeneration markers and the restoration of denervated muscle morphology.

Conclusion

Based on the clinical and animal data analysis, we conclude that muscle flap rotation provides a platform for angiogenesis in the acceleration of nerve regeneration. It appears that the muscle flap rotation augmented the nerve regeneration process which may be beneficial for nerve repair in clinical application.

One-Stage versus Two-Stage Arteriovenous Loop Reconstructions: An Experience on 103 Cases from a Single Center

BACKGROUND

The optimal time for flap anastomosis to an arteriovenous loop remains controversial. Whether perforator flaps and axially vascularized muscle or fasciocutaneous flaps lead to comparable outcomes in conjunction with arteriovenous loops has not been investigated.

METHODS

Medical records from 103 patients undergoing arteriovenous loop reconstruction (76 one-stage and 27 two-stage) between 2007 and 2017 were reviewed. Postoperative outcomes were compared between one- and two-stage arteriovenous loop reconstructions and different types of free flaps.

RESULTS

Rates of flap thrombosis, major wound complications, and flap failure did not differ significantly between one- and two-stage arteriovenous loop reconstructions (14.47 percent versus 11.11 percent, p = 1.00; 30.26 percent versus 25.93 percent, p = 0.67; and 10.53 percent versus 7.41 percent, p = 1.00). For two-stage arteriovenous loop reconstructions, the time interval between arteriovenous loop placement and flap anastomosis was a predictor for thrombotic events (OR, 1.31; p < 0.05). Anterolateral thigh flaps in conjunction with arteriovenous loops showed higher failure rates (33.33 percent) compared with all other flaps (6.59 percent) (p < 0.05) and combined latissimus dorsi and parascapular flaps (0 percent) (p < 0.05). Thrombosis rates were higher in anterolateral thigh flaps (33.33 percent) compared with all other flaps (10.99 percent; p = 0.056), and combined latissimus dorsi and parascapular flaps (0 percent; p < 0.05).

CONCLUSIONS

Two-stage arteriovenous loop reconstructions do not lead to increased postoperative complications compared to one-stage arteriovenous loop reconstructions and may be favorable in complicated cases because of shorter operative times. To avoid an increased thrombosis risk, flap anastomosis should not be delayed beyond 10 days in two-stage arteriovenous loop reconstructions. Anterolateral thigh flaps are less suitable for arteriovenous loop reconstructions because of higher complication rates.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Inhibitory effects of miR‑26b‑5p on thyroid cancer

In order to examine the inhibitory effects of microRNA (miR)‑26b‑5p on thyroid cancer (TC), the clinicopathological features and pathological tissues of 67 patients were collected. The expression levels of miR‑26b‑5p were detected in TC and paracarcinoma tissues by quantitative polymerase chain reaction, and the association between miR‑26b‑5p expression and the clinicopathological features of the patients was analyzed using t‑test or one‑way analysis of variance. In addition, B‑CPAP TC cells were infected with a lentivirus to induce miR‑26b‑5p overexpression and proliferation was detected by Cell Counting kit‑8. Subsequently, migration and invasion were detected by Transwell and Matrigel assays, respectively, and the molecular mechanism of action was investigated by western blotting. The results demonstrated that the expression levels of miR‑26b‑5p were significantly lower in TC tissues compared with paracarcinoma tissues (P<0.01), and miR‑26b‑5p was associated with lymph node metastasis (P<0.05). In addition, overexpression of miR‑26b‑5p inhibited the proliferation, invasion and migration of B‑CPAP cells. Western blot analysis demonstrated that the protein expression levels of phosphorylated glycogen synthase kinase‑3β (pGsk‑3β) were decreased, and the expression of β‑catenin was decreased in B‑CPAP cells overexpressing miR‑26b‑5p. These results demonstrated that miR‑26b‑5p may exert antitumor activity. In addition, at the molecular level, these effects may be associated with the Gsk‑3β/β‑catenin pathway.