＜Editors' Choice＞ Supernatant from activated omentum accelerates wound healing in diabetic mice wound model.

Diabetic wounds are considered one of the most frequent and severe complications of diabetes mellitus. Recently, the omentum has been used in diabetic wound healing because of its tissue repair properties. The activated omentum is richer in growth factors than the inactivated, thereby contributing to the wound healing process. To further investigate the effect of activated omentum conditioned medium (aOCM) on diabetic wound healing, we injected supernatant from aOCM, saline-OCM (sOCM), inactivated-OCM (iOCM), and medium (M) subcutaneously upon creation of a cutaneous wound healing model in diabetic mice. Wound area (%) was evaluated on days 0, 3, 5, 7, 9, 11, 14, 21, and 28 post-operation. At 9 and 28 d post-operation, skin tissue was harvested and assessed for gross observation, neovascularization, peripheral nerve fiber regeneration, and collagen deposition. We observed that aOCM enhanced the wound repair process, with significant acceleration of epidermal and collagen deposition in the surgical lesion on day 9. Additionally, aOCM displayed marked efficiency in neovascularization and peripheral nerve regeneration during wound healing. Thus, aOCM administration exerts a positive influence on the diabetic mouse model, which can be employed as a new therapy for diabetic wounds.

＜Editors' Choice＞ Long-term outcomes of lateral skull base reconstruction with a free omental flap and facial nerve reconstruction.

In lateral skull base reconstruction, it is necessary to seal the defect in the lateral skull base, fill the dead space, and, sometimes, reconstruct the facial nerve. However, this procedure is difficult to perform with a standard musculocutaneous flap. Therefore, for such cases, an omental flap is used in our hospital because of its flexibility. In this study, we report our experience with the procedure (lateral skull base reconstruction with a free omental flap) and its long-term outcome and facial nerve reconstruction, with special focus on facial nerve recovery. This study is a technical note and a retrospective review. It was conducted in Nagoya University Hospital. Overall, 16 patients (12 women and 4 men; mean age: 55.1 years) underwent lateral skull base reconstruction with a free omental flap after subtotal temporal bone resection or lateral temporal bone resection during 2005-2017. The main outcome measures were postoperative complications and facial nerve recovery: Yanagihara score and House-Brackmann grading system. Complications included partial necrosis and minor cerebrospinal fluid leakage in 2 patients. Facial nerve recovery could be observed more than 12 months after surgery, with a mean Yanagihara score of 19.6 and House-Brackmann grade of 3.60. The free omental flap is a reliable method for lateral skull base reconstruction, especially in cases where facial nerve reconstruction is needed. To the best of our knowledge, this is the first report on facial nerve recovery after lateral skull base reconstruction.

Artificial PGA/Collagen-based Bilayer Conduit in Short Gap Interposition Setting Provides Comparable Regenerative Potential to Direct Suture.

The aim of this study was to evaluate whether the Nerbridge, an artificial polyglycolic acid conduit with collagen matrix, is comparable to direct nerve suture in a rat sciatic nerve injury model in a short-gap interposition (SGI) setting. Methods: Sixty-six female Lewis rats were randomly divided into the sham group (n = 13); no reconstruction (no-recon) group (n = 13; rat model with 10 mm sciatic nerve defect); direct group (n = 20; rat sciatic nerve injury directly connected by 10-0 Nylon); and SGI group (n = 20; sciatic nerve injury repaired using 5-mm Nerbridge). Motor function and histological recovery were evaluated. The sciatic nerve and gastrocnemius muscle were harvested for quantification of the degree of nerve regeneration and muscle atrophy. Results: The SGI and direct groups achieved equal recovery in both functional and histological outcomes. At weeks 3 and 8 postsurgery, there was a significant improvement in the sciatic functional index of the SGI group when compared with that of the no-recon group (P < 0.05). Furthermore, the direct and SGI groups had less muscle atrophy at 4 and 8 weeks postsurgery compared with the no-recon group (P < 0.05). The axon density and diameter at the distal site in the SGI group were significantly higher than that in the no-recon group and comparable to that in the direct and sham groups. Conclusion: An artificial nerve conduit has equal potential as direct suture in motor nerve reconstruction when used in the SGI setting.

Peripheral Nerve Regeneration Using Different Germ Layer-Derived Adult Stem Cells in the Past Decade.

Peripheral nerve injuries (PNIs) are some of the most common types of traumatic lesions affecting the nervous system. Although the peripheral nervous system has a higher regenerative ability than the central nervous system, delayed treatment is associated with disturbances in both distal sensory and functional abilities. Over the past decades, adult stem cell-based therapies for peripheral nerve injuries have drawn attention from researchers. This is because various stem cells can promote regeneration after peripheral nerve injuries by differentiating into neural-line cells, secreting various neurotrophic factors, and regulating the activity of in situ Schwann cells (SCs). This article reviewed research from the past 10 years on the role of stem cells in the repair of PNIs. We concluded that adult stem cell-based therapies promote the regeneration of PNI in various ways.

A Novel Technique to Lengthen the Reverse Latissimus Dorsi Muscle Flap Arc.

Reconstruction of the lower lumbar region is challenging for surgeons due to limited locoregional flap choices. The latissimus dorsi muscle flap is a mainstay for this area; however, there are several limitations, including that the dominant thoracodorsal artery and vein pedicle-based flaps are not reachable for reconstruction of the lumbar region, while perforator of intercostal artery and veins pedicle-based reverse latissimus dorsi (RLD) flap mobility is limited by including multiple perforators. Here, we describe a novel operative technique that lengthens the rotation arc of RLD muscle flaps. The surgical technique is as follows: RLD is elevated based on lower perforator of intercostal artery and veins (usually including two of the eighth-11th perforators); thoracodorsal artery and vein are ligated; and the flap is mobilized toward the defect. When RLD was not reachable to the defect, the far aspect of the intercostal artery and vein from the defect was ligated and the perforator was elevated with the near aspect of the intercostal artery and vein from intercostal space. Because the intercostal space measured between approximately 3 cm and 4 cm, this dissection gained 3-4 cm of rotational arc per intercostal space. Moreover, because the lower ribs follow a medio-cranial to latero-caudal direction, this dissection enabled the flap to extend latero-caudally or medio-cranially while maintaining its blood supply. Other applications using this technique may involve expanding the RLD flap arc caudally, ventrally, and ipsilaterally. We believe this new technique provides a reliable alternative for lower back reconstruction.

Multiple Thrombi during Microvascular Anastomosis Caused by Decreased Antithrombin Activity: A Case Report.

With recent advances in microsurgical instruments and technique, microvascular anastomosis has become a universal surgical technique; however, thrombosis still presents in a number of cases. Tension, twisting, and compression to the anastomotic site are the main causes of thrombus; however, disorder of the coagulation-fibrinolysis system also need to be considered. To date, only few reports exist regarding thrombosis caused by disorder of coagulant system in microvascular anastomosis. Here we report our 3 cases in which multiple thrombus formation occurred intraoperatively caused by decrease of antithrombin (AT) activity. AT activity was measured twice a day after vascular anastomosis: after surgery and up to 3 days after surgery. Thrombosis was not observed in any of the 3 patients intraoperatively after the transfusion, or thrombosis was not observed in any of 3 patients intraoperatively after the transfusion or postoperatively, and no other complications were observed. In these 3 cases, the thrombus was not caused by technical error or other previously described factors. The observed intraoperative decrease in AT activity was thought to be caused by thrombus formation. It is important that microsurgeons are reminded that disorders of the coagulation-fibrinolysis system could cause thrombosis.

Increased Defect Size is Associated with Increased Complication Rate after Free Tissue Transfer for Midanterior Skull-Base Reconstruction.

Objective Complications after skull-base reconstruction are often problematic. We consider that local factors, for example, localization of defect areas are possible risk factors. This study aimed to investigate our case series of skull-base reconstructions in our institution and to identify local risk factors that predispose to wound complications. Design This study is presented as a retrospective study. Setting Research work was took place at Nagoya University Hospital. Participants Forty-eight patients who had undergone reconstruction after midanterior skull-base resection between January 2004 and December 2015 were included in this study. Defects apart from the skull-base were categorized into nasal and paranasal cavity (N), orbit (O), palate (P), and facial skin (S). Postoperative local complications including cerebrospinal fluid (CSF) leakage, local infection, wound dehiscence (fistula in face or palate), and flap necrosis (partial or total) were investigated. Main Outcome Measures Main outcome measures were postoperative complications in patients with each defect. Results Apart from the skull-base, defects included 28 ONP (58.3%), 10 ONPS (20.8%), 3 ON (6.3%), 3 ONS (6.3%), 1 NP (2.1%), and 1 OS (2.1%). Comparison based on numbers of resected regions revealed that a significantly higher complication rate was seen in patients with four resected regions than in those with three regions (90.0% vs. 45.2%, p < 0.05). Conclusion There was a trend suggesting that more resected regions corresponded to a greater risk of complications in midanterior skull-base reconstruction. Reconstructive surgeons need to carefully consider the reconstruction of such complicated defects.

Erratum: Increased Defect Size is Associated with Increased Complication Rate after Free Tissue Transfer for Midanterior Skull-Base Reconstruction.

[This corrects the article DOI: 10.1055/s-0038-1676777.].

Nuss procedure for patients with pectus excavatum with a history of intrathoracic surgery.

BACKGROUND: The aim of this study was to demonstrate the feasibility and safety of the Nuss procedure for patients with pectus excavatum (PE) with a history of intrathoracic surgery. PATIENTS: From April 2010 to December 2013, we performed 6 cases of PE repair in patients with a history of intrathoracic surgery. The causes of previous operations were congenital cystic adenomatoid malformation in 4 patients and congenital diaphragmatic hernia in 2. The patients' median age was 5 years (range, 4-9 years) and median preoperative pectus severity index was 4.63 (range, 3.42-10.03). Their intraoperative and postoperative courses were reviewed retrospectively. RESULTS: The mean overall operation time was 127.5 ±â€¯17.0 minutes, and the mean operation time for endoscopic pneumolysis was 28.8 ±â€¯12.3 minutes. Intraoperative exploration for pleural adhesion revealed that the endoscopic approach in the previous operation was associated with low pleural adhesion, and the open thoracotomy or laparotomy approach was associated with low to high pleural adhesion. One patient developed a pneumothorax on the first postoperative day. All the other patients had uneventful postoperative courses. All the patients received bar removal 2-3 years after bar insertion. One patient developed atelectasis after bar removal. All the other patients had an uneventful postoperative course. The mean postoperative follow-up time after bar removal was 20.1 ±â€¯14.7 months. CONCLUSIONS: History of intrathoracic surgery seems not a contraindication for the Nuss procedure. However, perioperative complications should be carefully monitored in both the bar insertion and removal operations.

＜Editors' Choice＞ Effects of exosomes derived from the induced pluripotent stem cells on skin wound healing.

Recently, the effects of stem cell supernatants or exosomes, such as skin wounds, have attracted attention. However, the effects of the induced pluripotent stem (iPS) cell-derived exosomes (iPS-Exos) have not been investigated in detail. Here, we investigated the effects of iPS-Exos on skin wound healing using an animal model. We isolated iPS-Exos from the iPS cell culture media. Control exosomes were isolated from unused iPS cell culture media (M-Exos). We first observed the morphologic characteristics of the isolated exosomes and examined the expression of surface antigens. The effects of these exosomes on the migratory response and proliferation of fibroblasts were analyzed as well. Additionally, using a diabetic ulcer model, the effects of iPS-Exos and M-Exos on skin wound healing were investigated. Transmission electron microscope analysis demonstrated that the size of iPS-Exos (120 ± 25 nm) was significantly larger than that of M-Exos (≤ 100 nm). Flow cytometry analyses showed that iPS-Exos were positive for CD9, CD63, and CD81, whereas they were negative for HLA-ABC and -DR expression. The migratory ability of fibroblasts cocultured with iPS-Exos was shown to be higher than that of the cells cocultured with M-Exos, as demonstrated using scratch assay. Skin wound healing model results showed that the administration of iPS-Exos results in a faster wound closure compared with that observed in the M-Exo group. In conclusion, the results obtained here indicate that iPS-Exos may promote the migration of fibroblasts in vitro and in vivo, suggesting the possibility of using iPS-Exos for the treatment of diabetic ulcer.

Effects of Tissue Component Volumes on Vascular Resistance in Free Flaps.

Background A successful free flap transfer is achieved, in part, by having a thorough understanding of vascular anatomy and blood flow dynamics. We previously reported that vascular resistance differs by type of free flap. To test the hypothesis that the difference reflects the proportion of tissue components within free flaps, we calculated blood flow and vascular resistance for free flaps in which we determined the volume of each tissue component. Methods Measurements and calculations were made for 40 free flap transfers performed at our hospital: 7 radial forearm flaps, 14 anterolateral thigh flaps, and 19 rectus abdominis myocutaneous flaps. Results The vascular resistance of free flaps was inversely related to the volume of each tissue component. Univariate regression analysis revealed that muscle volume correlated most closely with resistance (r = 0.881), followed by skin (r = 0.622), and fat (r = 0.577). Multiple regression analysis confirmed the relationship between combined muscle and fat volume and resistance (R2 = 0.865). Conclusions A strong inverse correlation exists between vascular resistance and combined muscle and fat tissue volume in flaps. It may be helpful to consider these relationships when making decisions regarding choice of free flap and recipient vessels.