Pericyte-specific deletion of ninjurin-1 induces fragile vasa vasorum formation and enhances intimal hyperplasia of injured vasculature.

Adventitial abnormalities including enhanced vasa vasorum malformation are associated with development and vulnerability of atherosclerotic plaque. However, the mechanisms of vasa vasorum malformation and its role in vascular remodeling have not been fully clarified. We recently reported that ninjurin-1 (Ninj1) is a crucial adhesion molecule for pericytes to form matured neovessels. The purpose is to examine if Ninj1 regulates adventitial angiogenesis and affects the vascular remodeling of injured vessels using pericyte-specific Ninj1 deletion mouse model. Mouse femoral arteries were injured by insertion of coiled wire. Four weeks after vascular injury, fixed arteries were decolorized. Vascular remodeling, including intimal hyperplasia and adventitial microvessel formation were estimated in a three-dimensional view. Vascular fragility, including blood leakiness was estimated by extravasation of fluorescein isothiocyanate (FITC)-lectin or FITC-dextran from microvessels. Ninj1 expression was increased in pericytes in response to vascular injury. NG2-CreER/Ninj1loxp mice were treated with tamoxifen (Tam) to induce deletion of Ninj1 in pericyte (Ninj1 KO). Tam-treated NG2-CreER or Tam-nontreated NG2-CreER/Ninj1loxp mice were used as controls. Intimal hyperplasia was significantly enhanced in Ninj1 KO compared with controls. Vascular leakiness was significantly enhanced in Ninj1 KO. In Ninj1 KO, the number of infiltrated macrophages in adventitia was increased, along with the expression of inflammatory cytokines. In conclusion, deletion of Ninj1 in pericytes induces the immature vasa vasorum formation of injured vasculature and exacerbates adventitial inflammation and intimal hyperplasia. Thus, Ninj1 contributes to the vasa vasorum maturation in response to vascular injury and to reduction of vascular remodeling.NEW & NOTEWORTHY Although abnormalities of adventitial vasa vasorum are associated with vascular remodeling such as atherosclerosis, the mechanisms of vasa vasorum malformation and its role in vascular remodeling have not been fully clarified. The present study provides a line of novel evidence that ninjurin-1 contributes to adventitial microvascular maturation during vascular injury and regulates vascular remodeling.

Predictive Model for Postoperative Ambulatory Function after Lower Extremity Bypass in Chronic Limb-Threatening Ischemia.

BACKGROUND: In chronic limb-threatening ischemia, maintenance or recovery of ambulatory function is an important goal of treatment. This study aimed to develop a predictive model for ambulatory ability 1 year after bypass based on preoperative risk factors, including the Wound, Ischemia, and foot Infection (WIfI) classification. METHODS: We analyzed 146 patients with chronic limb-threatening ischemia (154 limbs) who underwent bypass to below the knee arteries. The patients were classified into 2 groups based on ambulatory status 1 year postoperatively: postoperative ambulation (99 patients, 104 limbs) and postoperative nonambulation (47 patients, 50 limbs). Various factors associated with postoperative ambulation were analyzed and a predictive model of postoperative ambulation was developed. RESULTS: Multivariate logistic regression analysis detected preoperative nonambulatory status, functional nonindependence in daily living, older age, WIfI wound grade 3, chronic obstructive pulmonary disease, and hemodialysis as independent risk factors for postoperative nonambulation. The predictive scoring model (scores ranging from -5.0 to 4.4) comprising these risk factors discriminated the postoperative ambulatory status well: the probabilities of postoperative ambulatory ability were ≥85% in those with a score ≤-2, 50% in those with a score of zero, and ≤15% in those with a score ≥2. The area under the receiver operating characteristic curve was 0.898, indicating good performance of the model. CONCLUSIONS: Preoperative nonambulatory status, functional nonindependence, advanced age, high WIfI wound grade, chronic obstructive pulmonary disease, and hemodialysis were important predictors of postoperative nonambulatory status. The predictive model will help us identify patients who will benefit from bypass surgery.

Ninjurin 1 mediates peripheral nerve regeneration through Schwann cell maturation of NG2-positive cells.

Ninjurin 1 (Ninj1) is identified as a peripheral nerve injury-induced protein. However, the role of Ninj1 in nerve regeneration is unclear. Schwann cells (SCs) and microvasculature are critical for peripheral nerve regeneration. SCs precursors and microvascular pericytes (PCs), which are nerve/glial antigen 2 (NG2)-positive cells are observed in peripheral nervous system. In this study, we investigated the role of Ninj1 in peripheral nerve regeneration using NG2+cell-specific inducible deletion of Ninj1 mouse model. The number of NG2+cells, which were associated with and without microvessels was increased after sciatic nerve crush injury. There was a significant increase in the expression of Ninj1 and EphA7 in the injured nerve tissue. This increase was mostly observed in NG2+cells. Genetic tracing of NG2+cells was performed using tamoxifen (Tam) treatment on NG2CreERT:R26R-tdTomato mice. The sciatic nerve was injured following the Tam-treatment, then tdTomato-expressing SCs were mostly observed in regenerated SCs at 21 days after nerve injury. Ninj1 gene knockout (Ninj1 KO) in NG2+cells was induced using NG2CreERT:Ninj1loxp mice. Tam-treated-NG2CreERT or Tam-nontreated NG2CreERT:Ninj1loxp mice were used as controls. Following Tam-treatment, the sciatic nerve in each group was injured. Ninj1KO significantly attenuated the expression of the myelin binding protein (MBP) as well as the number of myelinated axons. The expression of MBP in cultured SCs was significantly reduced by SiRNA-mediated Ninj1 knockdown (KD). Ninj1KD also attenuated the differentiation of SCs by isolated EphA7+multipotent PCs. The current data indicate that Ninj1 plays a vital role in peripheral nerve regeneration. This is observed particularly in the myelination process of NG2+cells including SCs precursors and multipotent PCs.

Super-Elderly Case of Acute Lower Limb Ischemia Treated with Indigo Aspiration System in Japan.

The Indigo Aspiration System (Penumbra Ltd., Alameda, CA, USA), a catheter-based device intended for the endovascular removal of clots from peripheral arteries and veins, was launched in Japan to treat acute limb ischemia after the cessation of urokinase sales. The initial application of this system in Japan was on a 96-year-old male patient. He was diagnosed with acute lower limb ischemia, which was caused by an embolism from a left common iliac artery aneurysm. The treatment significantly enhanced the perfusion to his left foot. This case report elaborates on the patient's treatment experience and discusses the indications for using the device.

NG2-positive pericytes regulate homeostatic maintenance of slow-type skeletal muscle with rapid myonuclear turnover.

BACKGROUND: Skeletal muscle comprises almost 40% of the human body and is essential for movement, structural support and metabolic homeostasis. Size of multinuclear skeletal muscle is stably maintained under steady conditions with the sporadic fusion of newly produced myocytes to compensate for the muscular turnover caused by daily wear and tear. It is becoming clear that microvascular pericytes (PCs) exhibit myogenic activity. However, whether PCs act as myogenic stem cells for the homeostatic maintenance of skeletal muscles during adulthood remains uncertain. METHODS: We utilized PC-fused myofibers using PC-specific lineage tracing mouse (NG2-CreERT/Rosa-tdTomato) to observe whether muscle resident PCs have myogenic potential during daily life. Genetic PC deletion mouse model (NG2-CreERT/DTA) was used to test whether PC differentiates to myofibers for maintenance of muscle structure and function under homeostatic condition. RESULTS: Under steady breeding conditions, tdTomato-expressing PCs were infused into myofibers, and subsequently, PC-derived nuclei were incorporated into myofibers. Especially in type-I slow-type myofibers such as the soleus, tdTomato+ myofibers were already observed 3 days after PC labeling; their ratio reached a peak (approximately 80%) within 1 month and was maintained for more than 1 year. Consistently, the NG2+ PC-specific deletion induced muscular atrophy in a slow-type myofiber-specific manner under steady breeding conditions. The number of myonucleus per volume of each myofiber was constant during observation period. CONCLUSIONS: These findings demonstrate that the turnover of myonuclei in slow-type myofibers is relatively fast, with PCs acting as myogenic stem cells-the suppliers of new myonuclei under steady conditions-and play a vital role in the homeostatic maintenance of slow-type muscles.

A case of lymphoma mimicking infected internal iliac artery aneurysm.

BACKGROUND: Malignant lymphoma rarely mimics an infected arterial aneurysm and a ruptured arterial aneurysm because of similar imaging findings, leading to misdiagnosis. The hematomas of ruptured aneurysms are radiologically difficult to distinguish from those of malignant lymphoma in emergency settings. Hence, a definitive diagnosis is crucial to avoid unnecessary surgery. CASE PRESENTATION: A man in his 80s with hematuria and shock vital had right internal iliac artery aneurysm (IIAA) and perianeurysmal fluid retention, which appeared to be a ruptured or an infected aneurysm. Treatment was initiated for infected IIAA instead of for ruptured IIAA. Systemic inflammatory response syndrome developed, and the infectious sources were assessed. Pacemaker lead and urinary tract infections were identified and treated; however, blood pressure was unstable. The aneurysm was treated with endovascular aortic aneurysm repair following antibiotic therapy; however, fluid retention increased, and inflammatory status and hematuria deteriorated. Open surgical conversion was performed to manage the infected lesions. Although an iliopsoas abscess was detected during surgery and nephrectomy and ureterectomy were performed to control the hematuria, analysis of the removed tissues led to the pathological diagnosis of diffuse large B-cell lymphoma (DLBCL). CONCLUSIONS: We encountered a case of DLBCL with imaging findings mimicking an infected internal iliac artery aneurysm, and definitive diagnosis was made more than 2 months after the initial examination. Definitively diagnosing malignant lymphoma around an iliac artery aneurysm based merely on symptoms and imaging findings is extremely difficult. Thus, histological examination should be actively performed in atypical infected aneurysms.

Ninjurin1 Deletion in NG2-Positive Pericytes Prevents Microvessel Maturation and Delays Wound Healing.

The formation of mature vasculature through angiogenesis is essential for adequate wound healing, such that blood-borne cells, nutrients, and oxygen can be delivered to the remodeling skin area. Neovessel maturation is highly dependent on the coordinated functions of vascular endothelial cells and perivascular cells, namely pericytes (PCs). However, the underlying mechanism for vascular maturation has not been completely elucidated, and its role in wound healing remains unclear. In this study, we investigated the role of Ninjurin-1 (Ninj1), a new molecule mediating vascular maturation, in wound healing using an inducible PC-specific Ninj1 deletion mouse model. Ninj1 expression increased temporarily in NG2-positive PCs in response to skin injury. When tamoxifen treatment induced a decreased Ninj1 expression in PCs, the neovessels in the regenerating wound margins were structurally and functionally immature, but the total number of microvessels was unaltered. This phenotypic change is associated with a reduction in PC-associated microvessels. Wound healing was significantly delayed in the NG2-specific Ninj1 deletion mouse model. Finally, we showed that Ninj1 is a crucial molecule that mediates vascular maturation in injured skin tissue through the interaction of vascular endothelial cells and PCs, thereby inducing adequate and prompt wound healing.

Retinal Blood Velocity Waveform Characteristics With Aging and Arterial Stiffening in Hypertensive and Normotensive Subjects.

Purpose: We aimed to explore the velocity waveform characteristics of the retinal artery associated with age and the cardio-ankle vascular index (CAVI) as a conventional arterial stiffness marker by applying the Doppler optical coherence tomography (DOCT) flowmeter. Methods: In this cross-sectional study, DOCT flowmeter imaging was performed in 66 participants aged 21 to 83 years (17 men, 49 women) with no history of eye diseases and no systemic diseases, except for hypertension. Retinal blood velocity waveform was analyzed where several parameters in time (upstroke time, T1, T2, T3, and T4) and area under the waveform (area elevation, area declination, A1, A2, A3, and A4) were extracted. Systolic blood pressure-adjusted Pearson's coefficients were calculated to determine the correlations of each parameter with age or CAVI. Results: Corrected upstroke time (UTc) was the waveform parameter most positively correlated with age (r = 0.497, P < 0.001). Area declination was the waveform parameter most negatively correlated with age (r = -0.682, P < 0.001) and CAVI (r = -0.601, P < 0.001). Conclusions: We extracted the waveform parameters associated with the risks of arterial stiffening. The velocity waveform analysis of the retinal artery with DOCT flowmeter potentially could become a new method for arterial stiffness identification. Translational Relevance: DOCT flowmeter could evaluate arterial stiffening in a different way from the conventional method of measuring arterial stiffening using pressure waveform. Because the DOCT flowmeter can easily, quickly, and noninvasively provide a retinal blood velocity waveform, this system could be useful as a routine medical examination for arterial stiffening.

A Case of Chronic Limb-Threatening Ischemia with Heel Ulcers Cured by Revascularization and Partial Calcanectomy.

Ischemic limbs with infected heel ulcers are often difficult to salvage. We present a case of an 82-year-old woman who had bilateral heel ulcers owing to chronic limb-threatening ischemia. She underwent right femoral-terminal posterior tibial artery bypass surgery, but right calcaneus osteomyelitis occurred and inhibited wound healing. She underwent partial calcanectomy (PC), and her right heel healed six months after the bypass surgery. The ulcer on her left foot also healed after distal bypass and PC. We describe our experience with a patient who needed PC to cure her heel ulcers.

EphA7+ perivascular cells as myogenic and angiogenic precursors improving skeletal muscle regeneration in a muscular dystrophic mouse model.

Skeletal muscle has a capacity for muscular regeneration mediated by satellite cells (SCs) and non-SCs. Although it is proposed that non-SCs are attractive therapeutic targets for dystrophies, the biological properties of these cells remain unclear. We have recently identified novel multipotent pericytes (PCs), capillary stem cells (CapSCs) derived from the microvasculature. In the present study, we determined if CapSCs contributed to myogenic regeneration using muscular dystrophy mouse model. CapSCs were isolated as EphA7+NG2+PCs from the subcutaneous adipose tissues of GFP-transgenic mice. Co-culture with C2C12 myoblast cells showed that CapSCs effectively enhanced myogenesis as compared to controls including EphA7- PCs and adipose stromal cells (ASCs). CapSCs transplanted in cardiotoxin-injured gastrocnemius muscles were well differentiated into both muscle fibers and microvessels, as compared to controls. At three weeks after cell-transplantation into the limbs of the mdx/utrn-/-mouse, CapSCs increased the number of GFP+myofibers along with dystrophin expression and the area size of myofibers, and also enhanced the muscular mass and its performance, assessed by treadmill test as compared to controls. In conclusion, CapSCs have potent myogenic regeneration capacity and improved the pathological condition in a muscular dystrophy mouse. Thus, CapSCs are an attractive cellular source in regenerative therapy for muscular dystrophy.

Total arch replacement with bilateral extra-anatomical axillary artery bypass and frozen elephant trunk technique for Kommerell's diverticulum.

A Kommerell's diverticulum is a rare congenital aortic arch anomaly associated with a high rate of aortic rupture or dissection. Therefore, surgical or endovascular repair should be considered early. A 64-year-old man was incidentally found to have an aortic arch anomaly, Kommerell's diverticulum, with a right aberrant subclavian artery and distal arch aneurysm. Hybrid total arch replacement with bilateral extra-anatomical axillary artery bypass and frozen elephant trunk technique was performed. This particular surgical approach would be a treatment option for any type of Kommerell's diverticulum.

Fatal Vasospasm of the Coronary Arteries in a Patient Undergoing Distal Bypass Surgery and Endovascular Therapy for Threatened Lower Limbs Due to Acute Exacerbation of Peripheral Arterial Disease.

A 79-year-old man with a heavy smoking history presented with threatened lower limbs due to acute exacerbation of peripheral artery disease (PAD). He underwent emergent distal bypass surgery for the right leg and external iliac stenting for the left leg. Fatal coronary artery spasm (CAS) with ST segment changes on electrocardiography was observed 28 h after the procedures, resulting in cardiac arrest. Coronary angiography showed widespread CAS with improvement after intra-arterial nitroglycerin infusion. We should keep in mind that CAS may occur more frequently than expected in PAD patients, especially those who have not stopped smoking prior to revascularization.