Wound Healing and Angiogenesis through Combined Use of a Vascularized Tissue Flap and Adipose-Derived Stem Cells in a Rat Hindlimb Irradiated Ischemia Model. Plast Reconstr Surg. 2016;137:1486-1497. [PMID: 27119923 DOI: 10.1097/prs.0000000000002062]

Angiogenesis and flap-related research: A bibliometric analysis

Adequate blood supply, a prerequisite for flap survival after grafting, makes angiogenesis of the flap the biggest problem to be solved. Researches have been conducted around vascularisation in correlation with flap grafting. However, bibliometric analyses systematically examining this research field are lacking. As such, we herein sought to conduct comprehensive comparative analyses of the contributions of different researchers, institutions, and countries to this research space in an effort to identify trends and hotspots in angiogenesis and vascularisation in the context of flap grafting. Publications pertaining to angiogenesis and vascularisation in the context of flap grafting were retrieved from the Web of Science Core Collection. References were then analysed and plotted using Microsoft Excel 2019, VOSviewer, and CiteSpace V. In total, 2234 papers that were cited 40 048 times (17.63 citations/paper) were included in this analysis. The greatest number of studies were from the United States, with these studies exhibiting both the highest number of citations (13 577) and the greatest overall H-index (60). For The institutions that published the greatest number of studies were WENZHOU MEDICAL UNIVERSITY (681), while UNIVERSITY OF ERLANGEN NUREMBERG has the highest number of citations (1458), and SHANGHAI JIAO TONG UNIVERSITY holds the greatest overall H-index (20). The greatest number of studies in this research space were published by Gao WY, while Horch RE was the most commonly cited researcher in the field. The VOS viewer software clustered relevant keywords into three clusters, with clusters 1, 2, 3, and 4 corresponding to studies in which the keywords 'anatomy', 'survival', 'transplantation', 'therapy' most frequently appeared. The most promising research hotspot-related terms in this field included 'autophagy', 'oxidative stress', 'ischemia/reperfusion injury', which exhibited a most recent average appearing year (AAY) of 2017 and after. Generally speaking, the results of this analysis indicate that the number of articles exploring angiogenesis and flap-related research has risen steadily, with the United States and China being the two countries publishing the greatest proportion of studies in this field. The overall focus of these studies has shifted away from 'infratest and tissue engineering' towards 'mechanisms'. In the future, particular attention should be paid to emerging research hotspots, which include 'ischemia/reperfusion injury' and treatments for promoting vascularization, such as 'platelet-rich plasma'. In light of these findings, funding agencies should continue increasing their investment in the exploration of the concrete mechanisms and interventional therapeutic relevance of angiogenesis during flap transplantation.

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.

Different therapeutic effects between diabetic and non-diabetic adipose stem cells in diabetic wound healing

OBJECTIVE

This study aimed to investigate how adipose tissue-derived stem cells (ASCs) from diabetic and from non-diabetic rats affect wound healing in different microenvironments.

METHOD

The two types of ASC-rich cells were distinguished by characteristic surface antigen detection. The ASC-rich cells were transplanted into the wounds of diabetic and non-diabetic rats. Wound healing rates were compared and the healing process in the wound margin sections was used to determine how ASC-rich cells affect wound healing in different microenvironments.

RESULTS

ASC density was decreased in diabetic rats. The generation time of ASC-rich cells from diabetic rats (d-ASC-rich cells) was longer than that of ASC-rich cells from non-diabetic rats. The number of pre-apoptotic cells in the third generation (passage 3) of d-ASC-rich cells was higher than that among the ASC-rich cells from non-diabetic rats. CD31 and CD34 expression was higher in d-ASC-rich cells than in ASC-rich cells from non-diabetic rats, whereas CD44 and CD105 expression was lower than that in ASC-rich cells from non-diabetic rats. Transplantation of ASC-rich cells from non-diabetic rats promoted wound healing in both non-diabetic and diabetic rats. In contrast, d-ASC-rich cells and enriched nuclear cells only promoted wound healing in non-diabetic rats. ASC-rich cell transplantation promoted greater tissue regeneration than d-ASC-rich cell transplantation.

CONCLUSION

ASC-rich cells promoted wound healing in diabetic and non-diabetic rats. ASC density was lower in the adipose tissue of diabetic rats compared with non-diabetic rats. d-ASC-rich cells did not promote wound healing in diabetic rats, suggesting that caution is warranted regarding the clinical use of diabetic adipose stem cell transplantation for the treatment of diabetic wounds.

Adipose-derived stem cells improve grafted burn wound healing by promoting wound bed blood flow

BACKGROUND

Researchers have explored the use of adipose-derived stem cells (ASCs) as a cell-based therapy to cover wounds in burn patients; however, underlying mechanistic aspects are not completely understood. We hypothesized that ASCs would improve post-burn wound healing after eschar excision and grafting by increasing wound blood flow via induction of angiogenesis-related pathways.

METHODS

To test the hypothesis, we used an ovine burn model. A 5 cm2 full thickness burn wound was induced on each side of the dorsum. After 24 hours, the burned skin was excised and a 2 cm2 patch of autologous donor skin was grafted. The wound sites were randomly allocated to either topical application of 7 million allogeneic ASCs or placebo treatment (phosphate-buffered saline [PBS]). Effects of ASCs culture media was also compared to those of PBS. Wound healing was assessed at one and two weeks following the application of ASCs. Allogeneic ASCs were isolated, cultured and characterized from non-injured healthy sheep. The identity of the ASCs was confirmed by flow cytometry analysis, differentiation into multiple lineages and gene expression via real-time polymerase chain reaction. Wound blood flow, epithelialization, graft size and take and the expression of vascular endothelial growth factor (VEGF) were determined via enzyme-linked immunosorbent assay and Western blot.

RESULTS

Treatment with ASCs accelerated the patch graft growth compared to the control (p < 0.05). Topical application of ASCs significantly increased wound blood flow (p < 0.05). Expression of VEGF was significantly higher in the wounds treated with ASCs compared to control (p < 0.05).

CONCLUSIONS

ASCs accelerated grafted skin growth possibly by increasing the blood flow via angiogenesis induced by a VEGF-dependent pathway.

Mesenchymal stem cell-derived extracellular vesicles as a new therapeutic strategy for ocular diseases

Mesenchymal stem cells (MSCs) have attracted considerable attention for their activity in the treatment of refractory visual disorders. Since MSCs were found to possess the beneficial effects by secreting paracrine factors rather than direct differentiation, MSC-derived extracellular vesicles (EVs) were widely studied in various disease models. MSCs generate abundant EVs, which act as important mediators by exchanging protein and genetic information between MSCs and target cells. It has been confirmed that MSC-derived EVs possess unique anti-inflammatory, anti-apoptotic, tissue repairing, neuroprotective, and immunomodulatory properties, similar to their parent cells. Upon intravitreal injection, MSC-derived EVs rapidly diffuse through the retina to alleviate retinal injury or inflammation. Due to possible risks associated with MSC transplantation, such as vitreous opacity and pathological proliferation, EVs appear to be a better choice for intravitreal injection. Small size EVs can pass through biological barriers easily and their contents can be modified genetically for optimal therapeutic effect. Hence, currently, they are also explored for the possibility of serving as drug delivery vehicles. In the current review, we describe the characteristics of MSC-derived EVs briefly, comprehensively summarize their biological functions in ocular diseases, and discuss their potential applications in clinical settings.

Adipose-Derived Stem Cells and Ceiling Culture-Derived Preadipocytes Cultured from Subcutaneous Fat Tissue Differ in Their Epigenetic Characteristics and Osteogenic Potential

BACKGROUND

Adipose-derived stem cells and ceiling culture-derived preadipocytes can be harvested from subcutaneous adipose tissue. Little is known about the epigenetic differences, which may contribute to differences in osteogenic potential, between these cell types. The purpose of this study was to address the osteogenic potential and underlying epigenetic status of adipose-derived stem cells and ceiling culture-derived preadipocytes.

METHODS

Adipose-derived stem cells and ceiling culture-derived preadipocytes were cultured from abdominal subcutaneous fat tissues of four metabolically healthy, lean female patients. After 7 weeks of culture, cellular responses to osteogenic differentiation media were examined. To evaluate the osteogenic potentials of undifferentiated adipose-derived stem cells and ceiling culture-derived preadipocytes, two types of epigenetic assessment were performed using next-generation sequencing: DNA methylation assays with the Human Methylation 450K BeadChip, and chromatin immunoprecipitation assays for trimethylation of histone H3 at lysine 4.

RESULTS

Human ceiling culture-derived preadipocytes showed greater osteogenic differentiation ability than did adipose-derived stem cells. In an epigenetic survey of the promoters of four osteogenic regulator genes (RUNX2, SP7, ATF4, and BGLAP), the authors found a general trend toward decreased CpG methylation and increased trimethylation of histone H3 at lysine 4 levels in ceiling culture-derived preadipocytes as compared to adipose-derived stem cells, indicating that these genes were more likely to be highly expressed in ceiling culture-derived preadipocytes.

CONCLUSIONS

The surveyed epigenetic differences between adipose-derived stem cells and ceiling culture-derived preadipocytes were consistent with the observed differences in osteogenic potential. These results enhance the authors' understanding of these cells and will facilitate their further application in regenerative medicine.

Enhanced Survival and Accelerated Perfusion of Skin Flap to Recipient Site Following Administration of Human α1-Antitrypsin in Murine Models

Objective: Skin flaps are routinely used in reconstructive surgery yet remain susceptible to ischemia and necrosis. Distant flaps require lengthy time to detach causing patient discomfort. Human α1-antitrypsin (hAAT) is a clinically available serum glycoprotein. hAAT was shown to support mature vessel formation and enhance tissue survival following ischemia-reperfusion injuries. The purpose of the presented study was to examine the effect of hAAT on skin flap survival and distant "tube" flap perfusion through its recipient site. Approach: Random-pattern skin flaps were performed on mice treated with clinical-grade hAAT using three unique routes of administration (transgenic, i.p. and s.c. infiltration); necrotic area and tissue perfusion were assessed. Blockade of vascular endothelial growth factor (VEGF) and nitric oxide synthase (NOS) were used to explore aspects of mechanism of action. A distant tube flap model was performed to examine time to perfusion. Results: hAAT-treated mice displayed approximately two-fold smaller necrotic flap areas versus controls across all hAAT administration routes. Flaps displayed greater perfusion as early as 3 days postsurgery (64.6% ± 4.0% vs. 43.7% ± 1.7% in controls; p = 0.007). hAAT-mediated flap survival was prominently NOS dependent, but only partially VEGF dependent. Finally, distant flaps treated with hAAT displayed significantly earlier perfusion versus controls (mean 9.6 ± 1.6 vs. 13.1 ± 1.0 days; p = 0.0005). Innovation: The established safety record of hAAT renders it an attractive candidate toward improving skin flap surgery outcomes, particularly during VEGF blockade. Conclusions: hAAT treatment enhances survival and accelerates perfusion of skin flaps in animal models in a NOS-dependent manner, partially circumventing VEGF blockade. Further mechanistic studies are required.

Assisting Rapid Soft-Tissue Expansion with Adipose-Derived Stem Cells: An Experimental Study in a Pig Model

BACKGROUND

Rapid tissue expansion has been attempted, aiming at shortening the period of conventional expansion. However, it has scarcely been clinically applied because of its drawbacks such as low expansion efficiency and tissue destruction. Adipose-derived stem cell transplantation is a promising therapeutic method in regenerative medicine. However, its effects on rapid expansion remain poorly understood.

METHODS

Twenty-four expanders were implanted in the dorsum of 12 pigs. Rapid expansion persisted for 1 week with 20 ml of saline daily. The increased area of the expanded skin was measured. Histologic and ultrastructural analysis and cell tracking were performed. The expression of vascular endothelial growth factor, fibroblast growth factor-2, and epidermal growth factor was also determined.

RESULTS

The increased area of adipose-derived stem cell-grafted expanded skin (0.91 ± 0.06 cm) was significantly more than the non-adipose-derived stem cell-treated control (0.51 ± 0.05 cm) (p < 0.01). Enhanced tissue regeneration in the adipose-derived stem cell-grafted expanded skin was evidenced by increased skin thickness, proliferating cells, extracellular matrix, and vascularization (113 ± 19/mm versus control 59 ± 14/mm) (all p < 0.05). Higher expression of vascular endothelial growth factor and epidermal growth factor was observed in the adipose-derived stem cell-transplanted expanded skin (p < 0.01 and p < 0.05, respectively), whereas the expression of fibroblast growth factor-2 was higher in the non-adipose-derived stem cell-treated control (p < 0.05). Transmission electron microscopy showed that a high density of collagen fibers could be seen in the adipose-derived stem cell-treated expanded skin. Cell tracking showed that the positively stained cells could be seen.

CONCLUSION

For rapid tissue expansion, adipose-derived stem cell transplantation may limit tissue destruction and improve the expansion efficiency by promoting tissue regeneration.

Effects of Adipose-derived Mesenchymal Stem Cell Exosomes on Corneal Stromal Fibroblast Viability and Extracellular Matrix Synthesis

Background

Corneal stromal cells (CSCs) are components of the corneal endothelial microenvironment that can be induced to form a functional tissue-engineered corneal endothelium. Adipose-derived mesenchymal stem cells (ADSCs) have been reported as an important component of regenerative medicine and cell therapy for corneal stromal damage. We have demonstrated that the treatment with ADSCs leads to phenotypic changes in CSCs in vitro. However, the underlying mechanisms of such ADSC-induced changes in CSCs remain unclear.

Methods

ADSCs and CSCs were isolated from New Zealand white rabbits and cultured in vitro. An Exosome Isolation Kit, Western blotting, and nanoparticle tracking analysis (NTA) were used to isolate and confirm the exosomes from ADSC culture medium. Meanwhile, the optimal exosome concentration and treatment time were selected. Cell Counting Kit-8 and annexin V-fluorescein isothiocyanate/propidium iodide assays were used to assess the effect of ADSC- derived exosomes on the proliferation and apoptosis of CSCs. To evaluate the effects of ADSC- derived exosomes on CSC invasion activity, Western blotting was used to detect the expression of matrix metalloproteinases (MMPs) and collagens.

Results:

ADSCs and CSCs were successfully isolated from New Zealand rabbits. The optimal concentration and treatment time of exosomes for the following study were 100 μg/ml and 96 h, respectively. NTA revealed that the ADSC-derived exosomes appeared as nanoparticles (40-200 nm), and Western blotting confirmed positive expression of CD9, CD81, flotillin-1, and HSP70 versus ADSC cytoplasmic proteins (all P < 0.01). ADSC-derived exosomes (50 μg/ml and 100 μg/ml) significantly promoted proliferation and inhibited apoptosis (mainly early apoptosis) of CSCs versus non-exosome-treated CSCs (all P < 0.05). Interestingly, MMPs were downregulated and extracellular matrix (ECM)-related proteins including collagens and fibronectin were upregulated in the exosome-treated CSCs versus non-exosome-treated CSCs (MMP1: t = 80.103, P < 0.01; MMP2: t = 114.778, P < 0.01; MMP3: t = 56.208, P < 0.01; and MMP9: t = 60.617, P < 0.01; collagen I: t = -82.742, P < 0.01; collagen II: t = -72.818, P < 0.01; collagen III: t = -104.452, P < 0.01; collagen IV: t = -133.426, P < 0.01, and collagen V: t = -294.019, P < 0.01; and fibronectin: t = -92.491, P < 0.01, respectively).

Conclusion:

The findings indicate that ADSCs might play an important role in CSC viability regulation and ECM remodeling, partially through the secretion of exosomes.

Nanomedicine and advanced technologies for burns: Preventing infection and facilitating wound healing

According to the latest report from the World Health Organization, an estimated 265,000 deaths still occur every year as a direct result of burn injuries. A widespread range of these deaths induced by burn wound happens in low- and middle-income countries, where survivors face a lifetime of morbidity. Most of the deaths occur due to infections when a high percentage of the external regions of the body area is affected. Microbial nutrient availability, skin barrier disruption, and vascular supply destruction in burn injuries as well as systemic immunosuppression are important parameters that cause burns to be susceptible to infections. Topical antimicrobials and dressings are generally employed to inhibit burn infections followed by a burn wound therapy, because systemic antibiotics have problems in reaching the infected site, coupled with increasing microbial drug resistance. Nanotechnology has provided a range of molecular designed nanostructures (NS) that can be used in both therapeutic and diagnostic applications in burns. These NSs can be divided into organic and non-organic (such as polymeric nanoparticles (NPs) and silver NPs, respectively), and many have been designed to display multifunctional activity. The present review covers the physiology of skin, burn classification, burn wound pathogenesis, animal models of burn wound infection, and various topical therapeutic approaches designed to combat infection and stimulate healing. These include biological based approaches (e.g. immune-based antimicrobial molecules, therapeutic microorganisms, antimicrobial agents, etc.), antimicrobial photo- and ultrasound-therapy, as well as nanotechnology-based wound healing approaches as a revolutionizing area. Thus, we focus on organic and non-organic NSs designed to deliver growth factors to burned skin, and scaffolds, dressings, etc. for exogenous stem cells to aid skin regeneration. Eventually, recent breakthroughs and technologies with substantial potentials in tissue regeneration and skin wound therapy (that are as the basis of burn wound therapies) are briefly taken into consideration including 3D-printing, cell-imprinted substrates, nano-architectured surfaces, and novel gene-editing tools such as CRISPR-Cas.

Effect of Cell Seeding Density and Inflammatory Cytokines on Adipose Tissue-Derived Stem Cells: an in Vitro Study

Adipose tissue-derived stem cells (ASCs) are known to be able to promote repair of injured tissue via paracrine factors. However, the effect of cell density and inflammatory cytokines on the paracrine ability of ASCs remains largely unknown. To investigate these effects, ASCs were cultured in 8000 cells/cm², 20,000 cells/cm², 50,000 cells/cm², and 400,000 cells/cm² with and without 10 or 20 ng/ml tumor necrosis factor alpha (TNFα) and 25 or 50 ng/ml interferon gamma (IFNγ). ASC-sheets formed at 400,000 cells/cm² after 48 h of culture. With increasing concentrations of TNFα and IFNγ, ASC-sheets with 400,000 cells/cm² had increased production of angiogenic factors Vascular Endothelial Growth Factor and Fibroblast Growth Factor and decreased expression of pro-inflammatory genes TNFA and Prostaglandin Synthase 2 (PTGS2) compared to lower density ASCs. Moreover, the conditioned medium of ASC-sheets with 400,000 cells/cm² stimulated with the low concentration of TNFα and IFNγ enhanced endothelial cell proliferation and fibroblast migration. These results suggest that a high cell density enhances ASC paracrine function might beneficial for wound repair, especially in pro-inflammatory conditions.

Hydroxytyrosol contributes to cell proliferation and inhibits apoptosis in pulsed electromagnetic fields treated human umbilical vein endothelial cells in vitro

A variety of pulsed electromagnetic fields (PEMFs) have been experimentally and clinically used in an effort to promote wound healing, although the mechanisms involved remain unknown. The aim of the present study was to investigate the action of a novel protocol of co‑treatment with PEMFs and hydroxytyrosol (HTY) on the proliferation and differentiation potential of human umbilical vein endothelial cells (HUVECs). The HUVECs were assigned randomly into three groups: Control, PEMF‑treated and PEMF + HT‑treated. The intensity of the electromagnetic field used in this protocol was 2.25 mT, the frequency of the bursts was 50 Hz and the application time was 15 min. A Cell Counting kit‑8 (CCK‑8) assay was used to assess cell proliferation, and cell apoptosis was analyzed by TUNEL apoptosis assay kit and calcein‑acetoxymethyl/propidium iodide dual‑staining assay. In addition, protein and mRNA expression levels of protein kinase B (Akt), mechanistic target of rapamycin (mTOR), transforming growth factor (TGF)‑β1 and p53 were determined by western blotting and reverse transcription‑quantitative polymerase chain reaction assays, respectively. The CCK‑8 assay demonstrated that HTY contributed to HUVEC proliferation mediated by PEMFs in a time‑dependent manner. The Transwell assay and scratch wound results demonstrated that co‑treatment of HTY and PEMFs could increase HUVEC migration. Furthermore, the levels of apoptotic cells were reversed by pre‑incubation with HTY in the PEMF treatment group, while PEMF treatment alone had no such effect. The proteins and mRNA expression levels of Akt, mTOR, TGF‑β1 were elevated in co‑treatment of HTY and PEMFs, whereas there was no effect on levels of p53. Therefore, the results indicated that combined exposure of HUVECs to PEMFs and HTY exerted protective effects in HUVECs by promoting cell proliferation and inhibiting apoptosis. In conclusion, to the best of our knowledge, the present study was the first to demonstrate the beneficial roles of HTY and PEMF combined treatment in HUVECs, which may represent an effective treatment for wound healing.

Extracellular vesicles of ETV2 transfected fibroblasts stimulate endothelial cells and improve neovascularization in a murine model of hindlimb ischemia

Ischemia are common conditions related to lack of blood supply to tissues. Depending on the ischemic sites, ischemia can cause different diseases, such as hindlimb ischemia, heart infarction and stroke. This study aims to evaluate how extracellular vesicles (EVs) derived from ETV2 transfected fibroblasts affect endothelial cell proliferation and neovascularization in a murine model of hindlimb ischemia. Human fibroblasts were isolated and cultured under standard conditions and expanded to the 3th passage before use in experiments. Human fibroblasts were transduced with a viral vector containing the ETV2 gene. Transduced cells were selected by puromycin treatment. These cells were further cultured for collection of EVs, which were isolated from culture supernatant. Following co-culture with endothelial cells, EVs were evaluated for their effect on endothelial cell proliferation and were directly injected into ischemic tissues of a murine model of hindlimb ischemia. The results showed that EVs could induce endothelial cell proliferation in vitro and improved neovascularization in a murine model of hindlimb ischemia. Our results suggest that EVs derived from ETV2-transfected fibroblasts can be promising non-cellular products for the regeneration of blood vessels.

Improved Head and Neck Free Flap Outcome-Effects of a Treatment Protocol Adjustment from Pre- to Postoperative Radiotherapy

BACKGROUND

The impact of preoperative radiotherapy on microvascular reconstructive surgery outcome has been a subject of debate. However, data are conflicting and often dependent on local treatment protocols. We have studied the effects of radiotherapy in a unique, single-center setting where a treatment protocol change was undertaken from pre- to postoperative radiotherapy administration for microsurgical head and neck reconstructions.

METHODS

A cohort study was conducted for 200 consecutive head and neck free flap cases, where 100 were operated on before and 100 after the treatment protocol adjustment in 2006. Only direct cancer reconstructions were included. Complication rates of anastomosis-related (flap necrosis) and flap bed-related (infection, fistula, and wound dehiscence) complications were compared between irradiated and nonirradiated patients. A multivariate analysis was performed to correct for treatment period.

RESULTS

One hundred twenty-six patients had received radiotherapy before reconstruction due to cases of cancer recurrence. There were no significant differences in demographic data or risk factors between irradiated and nonirradiated cases. Irradiated cases had a higher rate of both flap loss (9.5% versus 1.4%; P = 0.034) and flap bed-related complications (29% versus 13%; P = 0.014). However, after multivariate analysis, there was only a significant relationship between preoperative irradiation and infection (odds ratio = 2.51; P = 0.033) and fistula formation (odds ratio = 3.13; P = 0.034).

CONCLUSIONS

The current single-center study clearly indicates that preoperative radiotherapy is a risk factor for both infection and fistula formation, most likely related to an impaired flap bed. We suggest postoperative radiotherapy administration whenever possible for oncological reasons, otherwise proper antibiotic cover and meticulous flap insetting to prevent radiation-related infection and fistula formation.