Current Status of Cardiac Regenerative Therapy Using Induced Pluripotent Stem Cells.

Heart failure (HF) is a life-threatening disorder and is treated by drug therapies and surgical interventions such as heart transplantation and left ventricular assist device (LVAD). However, these treatments can lack effectiveness in the long term and are associated with issues such as donor shortage in heart transplantation, and infection, stroke, or gastrointestinal bleeding in LVADs. Therefore, alternative therapeutic strategies are still needed. In this respect, stem cell therapy has been introduced for the treatment of HF and numerous preclinical and clinical studies are employing a range of stem cell varieties. These stem cells, such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have been shown to improve cardiac function and attenuate left ventricular remodeling. IPSCs, which have a capacity for unlimited proliferation and differentiation into cardiomyocytes, are a promising cell source for myocardial regeneration therapy. In this review, we discuss the following topics: (1) what are iPSCs; (2) the limitations and solutions for the translation of iPSC-CMs practically; and (3) the current therapeutic clinical trials.

Effect of concomitant mitral valve procedures for severe mitral regurgitation during left ventricular assist device implantation.

The effect of performing a concomitant mitral valve procedure (MVP) during continuous-flow left ventricular assist device (CF-LVAD) implantation has been reported for patients with moderate-to-severe mitral regurgitation (MR), but moderate MR is less of a clinical concern for CF-LVAD patients. There is a paucity of reports focusing on patients with severe MR. Thus, the purpose of this study was to analyze the effect of performing a concomitant MVP during CF-LVAD implantation in patients with severe preoperative MR. Between November 2003 and March 2016, 526 patients underwent primary implantation of a CF-LVAD at our center. Patients with severe MR who underwent a concomitant MVP were compared to those who did not in regard to overall survival, perioperative complications, postoperative echocardiography data, bridge-to-transplantation success, and CF-LVAD explantation. Of the 108 patients with severe MR, 26 underwent a concomitant MVP and 82 did not. These groups showed no difference in survival (p = 0.61). Additionally, the two groups had similar rates of postoperative right heart failure (p = 0.69) and readmissions (p = 0.42). The 24-month follow-up echocardiography results were also similar. Furthermore, the groups showed no difference in bridge-to-cardiac transplantation success (30.0% vs 25.0%, p = 0.80) or CF-LVAD explantation rates (0.0% vs 0.0%. p = 1.0). Our findings suggest that patients with severe MR who undergo a MVP during CF-LVAD implantation do not have superior outcomes to those who do not. However, assessments of other outcomes may show some benefits to performing concomitant MVPs.

Outcomes in patients who underwent a concomitant tricuspid valve procedure during left ventricular assist device implantation.

BACKGROUND: Study findings have been inconsistent regarding whether a concomitant tricuspid valve replacement or repair performed concurrently with continuous-flow left ventricular assist device (CF-LVAD) implantation has additive clinical benefit in patients with severe tricuspid valve regurgitation (TR). AIM OF STUDY: To determine the effect of performing a concomitant tricuspid valve procedure (TVP) at the time of CF-LVAD implantation on patient outcomes. METHODS: We retrospectively reviewed our single-institution experience in 526 patients who underwent primary implantation of a CF-LVAD between November 2003 and March 2016. We identified 59 (11.2%) patients who had severe TR at the time of implantation and analyzed the effect of performing a concomitant TVP at the time of CF-LVAD implantation on the rate of survival, incidence of postoperative right heart failure (RHF), recurrence of TR, and incidence of 30-day readmission. RESULTS: We did not observe a significant difference in the overall survival rate (P = .51), incidence of postoperative RHF (P = .26), or recurrence of TR (P = .73) between patients with severe TR who underwent a TVP and those who did not at the time of CF-LVAD implantation. However, the incidence of 30-day readmission was significantly lower in patients who underwent a TVP than in those who did not (P = .002). CONCLUSIONS: Performing a concomitant TVP at the time of CF-LVAD implantation did not improve patient outcomes but reduced the incidence of 30-day readmission.

Severe LVAD-related infections requiring surgical treatment: Incidence, predictors, effect on survival, and impact of device selection.

BACKGROUND: Left ventricular assist devices (LVADs) are being used more frequently for treating refractory, advanced heart failure. However, infection remains a frequent complication. In this study, we analyzed the incidence of severe infections in LVAD recipients to determine its impact on survival. METHODS: From May 2009 through March 2016, 437 patients with advanced heart failure underwent implantation of a continuous-flow LVAD (n = 314, HeartMate II LVAD [Abbott Laboratories, Abbott Park, IL]; n = 123 HeartWare HVAD [Medtronic, Minneapolis, MN]). We analyzed the rate of severe device infection requiring surgical intervention or involving sepsis and the impact of severe infection on outcomes in patients on long-term LVAD support. RESULTS: Infection occurred in 244 patients (HeartMate II, n = 186; HVAD, n = 58); severe infections developed in 160 patients (HeartMate II, n = 119; HVAD, n = 41). HeartMate II recipients had 344 severe infection events (0.63 events per patient-year [EPPY]), whereas HeartWare recipients had 89 severe infection events (0.42 EPPY; P = 0.047). HeartMate II recipients had a higher incidence of pump infections (P < 0.001). Severe infections did not significantly affect survival (P = 0.42). CONCLUSIONS: Although HeartMate II patients had a significantly higher incidence of pump infections requiring surgical treatment, survival was not adversely affected. The difference in postoperative infection rates may be an important factor in device type selection.

Device exchange from Heartmate II to HeartWare HVAD.

BACKGROUND: Despite technological advancements, pump durability and pump-related complications continue to affect and adversely impact the lives of patients with end-stage heart failure on left ventricular assist device (LVAD) support. In an attempt to avoid recurrent LVAD-related complications, there may be circumstances where it is clinically advantageous to exchange a patient's device from HeartMate II to HeartWare HVAD. However, there is a paucity of data that describes the safety and feasibility of such an approach. OBJECTIVE: We present the largest single-center series of HeartMate II (HMII) to HeartWare (HVAD) device exchanges. METHODS: A retrospective review of 11 patients who underwent HMII to HVAD exchange from 2012 to 2017 was conducted to evaluate patient characteristics, incidence of postoperative complications, and survival. RESULTS: Eleven male patients (mean age 55 ± 14.4 years) underwent HMII to HVAD device exchange. One patient expired on postoperative day 7 secondary to sepsis. One patient was lost-to-follow-up after 23 months. An additional three patients died at 5, 7, and 24 months. Mean follow-up after device exchange was 1555 ± 311 days for the remaining six patients. None of the 11 study patients underwent LVAD explant, further device exchange, or heart transplant. CONCLUSION: Exchange of an HMII LVAD to an HVAD can be performed safely with acceptable perioperative morbidity and mortality.

Bridging to a Long-Term Ventricular Assist Device With Short-Term Mechanical Circulatory Support.

Implanting short-term mechanical circulatory support (MCS) devices as a bridge-to-decision is increasingly popular. However, outcomes have not been well studied in patients who receive short-term MCS before receiving long-term left ventricular assist device (LVAD) support. We analyzed outcomes in our single-center experience with long-term continuous-flow (CF)-LVAD recipients with pre-implantation short-term MCS. From November 2003 through March 2016, 526 patients (mean age, 54.7 ± 13.5 years) with chronic heart failure (mean ejection fraction, 21.7 ± 3.6%) underwent implantation of either the HeartMate II (n = 403) or the HeartWare device (n = 123). Before implantation, 269 patients received short-term MCS with the TandemHeart, the Impella 2.5/5.0, an intra-aortic balloon pump (IABP), venoarterial extracorporeal membrane oxygenation (VA-ECMO), or the CentriMag. The short-term MCS patients were compared with the CF-LVAD-only patients regarding preoperative demographics, incidence of postoperative complications, and long-term survival. The 269 patients received the following short-term MCS devices: 57 TandemHeart, 27 Impella, 172 IABP, 12 VA-ECMO, and 1 CentriMag. Survival at 30 days, 6 months, 1 year, and 2 years was 94.2, 87.2, 79.4, and 72.4%, respectively, for CF-LVAD-only patients versus 91.0, 78.1, 73.4, and 65.6%, respectively, for short-term MCS + CF-LVAD patients (P = 0.17). Within the short-term MCS group, survival at 24 months was poorest for patients supported with VA-ECMO or the TandemHeart (P = 0.03 for both), and survival across all four time points was poorest for patients supported with VA-ECMO (P = 0.02). Short-term MCS was not an independent predictor of mortality in multivariate Cox regression models (hazard ratio = 1.12, 95% confidence interval = 0.84-1.49, P = 0.43). In conclusion, we found that using short-term MCS therapy-except for VA-ECMO-as a bridge to long-term CF-LVAD support was not associated with poorer survival.

HeartMate II implantation technique that spares the sternum and ascending aorta.

Left ventricular assist devices (LVADs) have become the standard therapy for patients with end-stage heart failure, and the use of LVADs for long-term support has grown exponentially over the past decade. As the number of LVAD implantations has increased, surgeons have faced more challenging cases, such as those in which the patient has previously undergone a sternotomy. The HeartMate II is one of the most widely implanted LVADs. The standard procedure for HeartMate II implantation is median sternotomy and sewing the outflow graft to the ascending aorta. However, in patients with sternal comorbidities, it can be advantageous to use a less invasive approach that avoids this procedure. We describe the case of a 64-year-old man with a history of end-stage ischemic cardiomyopathy who had previously undergone a median sternotomy and a coronary artery bypass grafting operation and had patent grafts. He required a HeartMate II LVAD (destination therapy), which was implanted via a left subcostal incision; the pump was placed subdiaphragmatically, and the outflow graft was sewed to the descending aorta to avoid a complicated redo cardiac operation via median sternotomy and to minimize the risk of injuring the patent bypass grafts. The patient survived for more than 500 days postoperatively. This approach is feasible and could be a safer method for implanting a HeartMate II device in patients with serious comorbidities that preclude the use of the traditional implantation techniques.

Outcomes in patients with advanced heart failure and small body size undergoing continuous-flow left ventricular assist device implantation.

Left ventricular assist devices (LVADs) have become a preferred treatment option for patients with end-stage heart failure when used as a bridge to transplant or as a destination therapy. However, the association between small body size and postoperative outcomes for continuous-flow (CF) LVAD recipients is still being studied. We sought to determine whether body surface area (BSA) is associated with patient outcomes after CF-LVAD implantation. The study cohort of our single-center, retrospective review consisted of all patients (n = 526) who underwent CF-LVAD implantation (n = 403 HeartMate II, n = 123 HeartWare) between November 2003 and March 2016 regardless of indication. Patients were stratified into 2 cohorts according to their BSA measurements: small BSA (<1.5 m2, n = 13) and non-small BSA (≥1.5 m2, n = 513). We compared the survival of the small-BSA cohort with that of the non-small-BSA cohort. Patients with a small BSA had lower survival rates at 1, 6, 12, and 24 months (76.9, 61.5, 53.8, and 38.5%, respectively) than did patients with a non-small BSA (90.4, 80.9, 74.7, and 67.6% respectively; overall, p = 0.004). Cox proportional hazard analysis showed that a small BSA was an independent predictor of postoperative mortality (hazard ratio = 0.22, 95% confidence interval = 0.05-0.97, p < 0.04). These findings highlight the adverse impact of a small BSA on outcomes after CF-LVAD implantation.

Effect of obesity on outcomes in patients undergoing implantation of continuous-flow left ventricular assist devices.

The purpose of this study was to analyze the effect of obesity on outcomes after continuous-flow left ventricular assist device (CF-LVAD) implantation. A single-center retrospective analysis was performed on 526 chronic heart failure patients who were implanted with the HeartMate II CF-LVAD (n = 403) or HeartWare HVAD (n = 123) between November 2003 and March 2016. Patients were stratified into 4 groups based on BMI: underweight (< 18.5 kg/m2, n = 18, 3.4%), normal-weight (18.5-25 kg/m2, n = 173, 32.9%), overweight (25-30 kg/m2, n = 182, 30.2%), and obese (> 30 kg/m2, n = 153, 33.5%). The underweight group was excluded because of its small sample size. Records were reviewed to determine the incidence of postoperative complications and survival. Survival at 1, 6, 12, and 24 months were similar among normal-weight (91.3, 84.4, 76.3, and 67.6%), overweight (90.4, 80.8, 76.5, and 69.6%), and obese patients (90.7, 74.7, 65.3, and 61.3%, p = 0.24). Additionally, obesity was not a significant predictor of mortality in Cox proportional hazard models (hazard ratio 0.98, 95% confidence interval 0.766-1.277, p = 0.13). These findings suggest that appropriately selected obese patients receive similar survival benefit from CF-LVADs compared to non-obese patients, and obesity should not serve as a contraindication to CF-LVAD implantation.

Acute kidney injury after implantation of a left ventricular assist device: a comparison of axial-flow (HeartMate II) and centrifugal-flow (HeartWare HVAD) devices.

Continuous-flow left ventricular assist devices (CF-LVADs) are increasingly being used to treat advanced, refractory chronic heart failure. Herein, we sought to determine the incidence of postoperative acute kidney injury (AKI) in axial-flow (HeartMate II; HM-II) and centrifugal-flow (HVAD) CF-LVAD recipients, as well as the effect of AKI on mortality. The study cohort comprised 520 patients who received a HM-II (n = 398) or HVAD (n = 122) at our center between November 2003 and March 2016. Their records were reviewed to determine the incidence of RIFLE-defined AKI after LVAD implantation. We compared the perioperative characteristics, postoperative complications, and survival rates of the patients with and without AKI and differentiated the outcomes based on device type (HM-II or HVAD). Seventy-five patients (14.4%) developed AKI postoperatively. Patients with AKI after LVAD implantation had significantly reduced survival compared to patients without AKI (p = 0.01). Cox proportional hazards models showed that AKI was a significant independent predictor of mortality (HR = 1.54, p = 0.03). Preoperative mechanical circulatory support and prolonged cardiopulmonary bypass time were independent predictors of AKI. The incidence of AKI was similar for HM-II and HVAD recipients (p = 0.25). There was no significant difference in AKI rates for the HM-II and HVAD recipients. Developing AKI adversely affected survival.

Predictive value of preoperative serum albumin levels on outcomes in patients undergoing LVAD implantation.

BACKGROUND: We performed a single-center retrospective analysis to determine whether preoperative serum albumin levels were associated with postoperative adverse events and short- and long-term survival in patients who underwent continuous-flow left ventricular assist device (CF-LVAD) implantation. METHODS: From November 2003 through March 2016, 526 patients underwent CF-LVAD implantation. Patients whose preoperative serum albumin level was normal (≥3.5 g/dL) were compared to patients with preoperative hypoalbuminemia (<3.5 g/dL), which was further categorized as moderate (2.5-3.5 g/dL) or severe (<2.5 g/dL). These groups were compared regarding preoperative demographics, incidence of postoperative complications, and long-term survival. RESULTS: Patients with hypoalbuminemia had higher serum levels of liver enzymes (P < 0.05) and total bilirubin (P < 0.001) and significantly lower platelet counts (P = 0.02) and prealbumin levels (P < 0.001) than patients with normal preoperative albumin levels. Survival in patients with moderate and severe preoperative hypoalbuminemia was significantly decreased compared with patients with normal preoperative serum albumin levels (P < 0.001). Preoperative hypoalbuminemia was also associated with higher incidences of postoperative infection, gastrointestinal bleeding, neurological dysfunction, and acute kidney injury (P ≤ 0.01 for all) but did not affect the success of bridge to transplantation or survival after transplantation. CONCLUSIONS: Our data demonstrated that there is a significant association of preoperative low serum albumin levels with postoperative adverse outcomes and lower survival rates. This highlights the importance of a patient's preoperative nutritional status on postoperative outcomes after CF-LVAD implantation.

Fast-degrading bioresorbable arterial vascular graft with high cellular infiltration inhibits calcification of the graft.

OBJECTIVE: Bioresorbable vascular grafts are biologically active grafts that are entirely reconstituted by host-derived cells through an inflammation-mediated degradation process. Calcification is a detrimental condition that can severely affect graft performance. Therefore, prevention of calcification is of great importance to the success of bioresorbable arterial vascular grafts. The objective of this study was to test whether fast-degrading (FD) bioresorbable arterial grafts with high cellular infiltration will inhibit calcification of grafts. METHODS: We created two versions of bioresorbable arterial vascular grafts, slow-degrading (SD) grafts and FD grafts. Both grafts had the same inner layer composed of a 50:50 poly(l-lactic-co-ε-caprolactone) copolymer scaffold. However, the outer layer of SD grafts was composed of poly(l-lactic acid) nanofiber, whereas the outer layer of FD grafts was composed of a combination of poly(l-lactic acid) and polyglycolic acid nanofiber. Both grafts were implanted in 8- to 10-week-old female mice (n = 15 in the SD group, n = 10 in the FD group) as infrarenal aortic interposition conduits. Animals were observed for 8 weeks. RESULTS: von Kossa staining showed calcification in 7 of 12 grafts in the SD group but zero in the FD group (P < .01, χ2 test). The cell number in the outer layer of FD grafts was significantly higher than in the SD grafts (SD, 0.87 ± 0.65 × 103/mm2; FD, 2.65 ± 1.91 × 103/mm2; P = .02). CONCLUSIONS: The FD bioresorbable arterial vascular graft with high cellular infiltration into the scaffold inhibited calcification of grafts.

TGF-ß receptor 1 inhibition prevents stenosis of tissue-engineered vascular grafts by reducing host mononuclear phagocyte activation.

Stenosis is a critical problem in the long-term efficacy of tissue-engineered vascular grafts (TEVGs). We previously showed that host monocyte infiltration and activation within the graft drives stenosis and that TGF-ß receptor 1 (TGF-ßR1) inhibition can prevent it, but the latter effect was attributed primarily to inhibition of mesenchymal cell expansion. In this study, we assessed the effects of TGF-ßR1 inhibition on the host monocytes. Biodegradable TEVGs were implanted as inferior vena cava interposition conduits in 2 groups of C57BL/6 mice (n = 25/group): unseeded grafts and unseeded grafts with TGF-ßR1 inhibitor systemic treatment for the first 2 wk. The TGF-ßR1 inhibitor treatment effectively improved TEVG patency at 6 mo compared to the untreated control group (91.7 vs. 48%, P < 0.001), which is associated with a reduction in classic activation of mononuclear phagocytes. Consistent with these findings, the addition of rTGF-ß to LPS/IFN-γ-stimulated monocytes enhanced secretion of inflammatory cytokines TNF-α, IL-12, and IL-6; this effect was blocked by TGF-ßR1 inhibition (P < 0.0001). These findings suggest that the TGF-ß signaling pathway contributes to TEVG stenosis by inducing classic activation of host monocytes. Furthermore, blocking monocyte activation by TGF-ßR1 inhibition provides a viable strategy for preventing TEVG stenosis while maintaining neotissue formation.-Lee, Y.-U., de Dios Ruiz-Rosado, J., Mahler, N., Best, C. A., Tara, S., Yi, T., Shoji, T., Sugiura, T., Lee, A. Y., Robledo-Avila, F., Hibino, N., Pober, J. S., Shinoka, T., Partida-Sanchez, S., Breuer, C. K. TGF-ß receptor 1 inhibition prevents stenosis of tissue-engineered vascular grafts by reducing host mononuclear phagocyte activation.

Left ventricular outflow tract closure during LVAD implantation: 2 cases of patients supported for over 6 years.

We previously reported a series of 5 patients with advanced heart failure and aortic insufficiency (AI) who underwent concomitant left ventricular outflow tract (LVOT) closure at the time of continuous-flow left ventricular assist device (CF-LVAD) implantation. Although this technique of treating AI has been shown to be effective in the short term, its long-term durability has not been well studied. Here, we report the long-term outcomes of two patients with severe AI who underwent LVOT closure at the time of CF-LVAD implantation. Each of the two patients survived for more than 6 years without any complications related to LVOT closure.

Cilostazol, Not Aspirin, Prevents Stenosis of Bioresorbable Vascular Grafts in a Venous Model.

OBJECTIVE: Despite successful translation of bioresorbable vascular grafts for the repair of congenital heart disease, stenosis remains the primary cause of graft failure. In this study, we investigated the efficacy of long-term treatment with the antiplatelet drugs, aspirin and cilostazol, in preventing stenosis and evaluated the effect of these drugs on the acute phase of inflammation and tissue remodeling. APPROACH AND RESULTS: C57BL/6 mice were fed a drug-mixed diet of aspirin, cilostazol, or normal chow during the course of follow-up. Bioresorbable vascular grafts, composed of poly(glycolic acid) mesh sealed with poly(l-lactide-co-ε-caprolactone), were implanted as inferior vena cava interposition conduits and followed up for 2 weeks (n=10 per group) or 24 weeks (n=15 per group). Both aspirin and cilostazol suppressed platelet activation and attachment onto the grafts. On explant at 24 weeks, well-organized neotissue had developed, and cilostazol treatment resulted in 100% graft patency followed by the aspirin (67%) and no-treatment (60%) groups (P<0.05). Wall thickness and smooth muscle cell proliferation in the neotissue of the cilostazol group were decreased when compared with that of the no-treatment group at 24 weeks. In addition, cilostazol was shown to have an anti-inflammatory effect on neotissue at 2 weeks by regulating the recruitment and activation of monocytes. CONCLUSIONS: Cilostazol prevents stenosis of bioresorbable vascular graft in a mouse inferior vena cava implantation model up to 24 weeks and is accompanied by reduction of smooth muscle cell proliferation and acute inflammation.

Vessel bioengineering.

The development of vascular bioengineering has led to a variety of novel treatment strategies for patients with cardiovascular disease. Notably, combining biodegradable scaffolds with autologous cell seeding to create tissue-engineered vascular grafts (TEVG) allows for in situ formation of organized neovascular tissue and we have demonstrated the clinical viability of this technique in patients with congenital heart defects. The role of the scaffold is to provide a temporary 3-dimensional structure for cells, but applying TEVG strategy to the arterial system requires scaffolds that can also endure arterial pressure. Both biodegradable synthetic polymers and extracellular matrix-based natural materials can be used to generate arterial scaffolds that satisfy these requirements. Furthermore, the role of specific cell types in tissue remodeling is crucial and as a result many different cell sources, from matured somatic cells to stem cells, are now used in a variety of arterial TEVG techniques. However, despite great progress in the field over the past decade, clinical effectiveness of small-diameter arterial TEVG (<6mm) has remained elusive. To achieve successful translation of this complex multidisciplinary technology to the clinic, active participation of biologists, engineers, and clinicians is required.

[Warfarin effects diminishment by the Clostridium butyricum preparation after cardiac surgery; report of a case].

A 55-year-old gentleman diagnosed with severe aortic insufficiency and annuloaortic ectasia underwent modified Bentall procedure using mechanical valve. Anticoagulation therapy with warfarin was introduced after surgery, but sufficient anticoagulation effect was not achieved with a large amount of dosage. After discontinuing the use of the Clostridium butyricum preparation on postoperative day 29, sufficient anticoagulationt effect was obtained within several days. Clostridium butyricum might change the vitamin K production in the intestinal bacterial flora and attenuated the anticoagulation effect of warfarin.

Acute Hemodynamic Compromise After Transcatheter Aortic Valve Replacement Due to Dynamic Left Ventricle Obstruction: A Systematic Review.

Acute hemodynamic compromise after transcatheter aortic valve replacement (TAVR) because of dynamic left ventricle (LV) obstruction (LVO), also known as suicide LV, is an infrequent but severe complication of TAVR that is poorly defined in previous studies. Understanding this complication is essential for its prompt diagnosis and optimal treatment. We conducted a systematic literature review using PubMed, Embase, Web of Science, and Medline databases for studies describing acute hemodynamic compromise after TAVR because of dynamic LVO or suicide LV. Each study was reviewed by 2 authors individually for eligibility, and a third author resolved disagreements. From a total of 506 studies, 25 publications were considered for the final analysis. The majority of patients with this condition were women demonstrating a hypertrophic septum, a small ventricle, and hyperdynamic contractility on pre-TAVR echocardiographic assessment. An intraventricular gradient before TAVR was found in half of the cases. Acute hemodynamic compromise after TAVR because of dynamic LVO manifested mainly as significant hypotension and occurred most often immediately after valve deployment. The LV outflow tract was the most common site of obstruction. Advanced therapies were required in nearly 65% of the cases. In conclusion, acute hemodynamic compromise after TAVR because of dynamic LVO occurred almost invariably in women. Echocardiography before TAVR may offer essential information to anticipate this complication. LV outflow tract obstruction appears to carry the highest risk of developing this phenomenon. Advanced therapies should be promptly considered as a bailout strategy in patients with hemodynamic collapse refractory to medical therapy.

Transmural macrophage migration into an arterial bioresorbable vascular graft promotes inflammatory-mediated response and collagen deposition for vascular remodeling.

Macrophages are the primary cell type orchestrating bioresorbable vascular graft (BVG) remodeling and infiltrate from three sources: the adjacent native vessel, circulating blood, and transmural migration from outer surface of the graft. To elucidate the kinetics of macrophage infiltration into the BVG, we fabricated two different bilayer arterial BVGs consisting of a macroporous sponge layer and a microporous electrospun (ES) layer. The Outer ES graft was designed to reduce transmural cell infiltration from the outer surface and the Inner ES graft was designed to reduce cell infiltration from the circulation. These BVGs were implanted in mice as infrarenal abdominal aorta grafts and extracted at 1, 4, and 8 weeks (n = 5, 10, and 10 per group, respectively) for evaluation. Cell migration into BVGs was higher in the Inner ES graft than in the Outer ES graft. For Inner ES grafts, the majority of macrophage largely expressed a pro-inflammatory M1 phenotype but gradually changed to tissue-remodeling M2 macrophages. In contrast, in Outer ES grafts macrophages primarily maintained an M1 phenotype. The luminal surface endothelialized faster in the Inner ES graft; however, the smooth muscle cell layer was thicker in the Outer ES graft. Collagen fibers were more abundant and matured faster in the Inner ES graft than that in the Outer ES graft. In conclusion, compared to macrophages infiltrating from the circulating blood, transmural macrophages from outside promote the acute inflammatory-mediated response for vascular remodeling and subsequent collagen deposition within BVGs. STATEMENT OF SIGNIFICANCE: To elucidate the kinetics of macrophage infiltration into the bioresorbable vascular graft (BVG), two different bilayer arterial BVGs were implanted in mice as infrarenal abdominal aorta grafts. Cell migration into BVGs was higher in the inner electrospun graft which cells mainly infiltrate from outer surface than in the outer electrospun graft which cells mainly infiltrate from the circulating blood. In the inner electrospun grafts, the majority of macrophages changed from the M1 phenotype to the M2 phenotype, however, outer electrospun grafts maintained the M1 phenotype. Collagen fibers matured faster in the Inner electrospun graft. Compared to macrophages infiltrating from the circulating blood, transmural macrophages from outside promote the acute inflammatory-mediated response for vascular remodeling and subsequent collagen deposition within BVGs.

Successful endovascular treatment of a ruptured superior mesenteric artery in a patient with Ehlers‒Danlos syndrome.

The purpose of this study was to describe covered-stent treatment of a ruptured dissection of the superior mesenteric artery (SMA) in a patient with Ehlers‒Danlos syndrome. The patient was a 13-year-old girl initially presenting with abdominal pain. Dissection and rupture of the SMA were diagnosed on detailed examination. Conservative treatment was performed initially because open surgery was considered high risk. However, the abdominal pain recurred, and we decided to perform endovascular therapy. A coronary artery covered stent was placed in the true lumen to close the entry site of the dissection. The false lumen was obliterated using a post-dilation technique, completing treatment of the rupture. The patient recovered uneventfully after surgery. Classic-type Ehlers‒Danlos syndrome was diagnosed on the basis of physical findings and genetic analysis. The stent has remained adequately patent as of 2 years after surgery. This case report shows that dissection and rupture of the SMA can be treated successfully using a covered coronary artery stent in a patient with Ehlers‒Danlos syndrome.