Mapping Endothelial-Macrophage Interactions in Diabetic Vasculature: Role of TREM2 in Vascular Inflammation and Ischemic Response.

Vasculopathies occur 15 years earlier in individuals with diabetes mellitus (DM) as compared to those without, but the underlying mechanisms driving diabetic vasculopathy remain incompletely understood. Endothelial cells (ECs) and macrophages (MΦ) are critical players in vascular wall and their crosstalk is crucial in diabetic vasculopathy. In diabetes, EC activation enables monocyte recruitment, which transmigrate into the intima and differentiate into macrophages (MΦ). Beyond this established model of diapedesis, EC-MΦ interplay is highly intricate and heterogenous. To capture these highly context dependent EC-MΦ interactions, we leveraged single-cell (sc)RNA-seq in conjunction with spatial transcriptome (ST)-seq profiling to analyze human mesenteric arteries from non-diabetic (ND) and type 2 diabetic (T2D) donors. We provide in this study a transcriptomic map encompassing major arterial vascular cells, e.g., EC, mononuclear phagocyte (MP), and T cells, and their interactions associated with human T2D. Furthermore, we identified Triggering Receptor Expressed on Myeloid Cells 2 ( TREM2) as a top T2D-induced gene in MP, with concomitant increase of TREM2 ligands in ECs. TREM2 induction was confirmed in mouse models of T2D and monocyte/MΦ subjected to DM-mimicking stimuli. Perturbing TREM2 with either an antibody or silencing RNA in MPs led to decreased pro-inflammatory responses in MPs and ECs and increased EC migration in vitro . In a mouse model of diabetes, TREM2 expression and its interaction with ECs are increased in the ischemic, as compared to non-ischemic muscles. Importantly, neutralization of TREM2 using a neutralizing antibody enhanced ischemic recovery and flow reperfusion in the diabetic mice, suggesting a role of TREM2 in promoting diabetic PAD. Finally, we verified that both TREM2 expression and the TREM2-EC-interaction are increased in human patients with DM-PAD. Collectively, our study presents the first atlas of human diabetic vessels with a focus on EC-MP interactions. Exemplified by TREM2, our study provides valuable insights into EC-MΦ interactions, key processes contributing to diabetic vasculopathies and the potential of targeting these interactions for therapeutic development.

Surgical outcomes of patients with inferior vena cava leiomyosarcoma.

INTRODUCTION: Primary vascular leiomyosarcomas are incredibly rare and have a poor prognosis. The purpose of this study was to analyze the surgical outcomes of patients with primary inferior vena cava (IVC) leiomyosarcoma. METHODS: We performed a retrospective review of IVC leiomyosarcoma resections performed at a single tertiary care hospital from 2014 to 2023. A total of 13 cases were analyzed, including 10 women and 3 men. The presenting symptoms, tumor characteristics, operative management, postoperative complications, and survival rates were assessed for each patient. RESULTS: The median patient age was 59 years (quartile [Q]1, 52 years; Q3, 68 years). The median tumor size was 7.0 cm (Q1, 6 cm; Q3, 12 cm). The median mitotic rate was 6 per 10 high-power fields (Q1, 2.5; Q3, 15.5). All 13 patients underwent grossly negative tumor resection, with 9 (69%) having microscopically negative margins (R0). No patient had lymph node involvement. The IVCs were managed with ligation in four patients for tumors already occluding the IVC and bovine pericardial patch angioplasty in seven patients or primary repair in two patients for patent IVCs. Concomitant right nephrectomy was performed in seven patients. Left renal vein ligation was performed in three patients, but no left nephrectomies were performed. Significant postoperative complications included one patient with lower extremity compartment syndrome, two patients with severe leg swelling, and one patient with arm swelling. The 30-day mortality rate was zero. Using the Kaplan-Meier product limit method, disease-specific survival was estimated to be 93%. CONCLUSIONS: Surgical resection is a feasible and effective oncologic treatment option for patients with IVC leiomyosarcoma. The IVC can be safely managed by ligation, primary repair, or patch angioplasty, depending on the prior patency of the IVC.

Feasibility and Intermediate Results of Transcarotid Revascularization with a Prosthetic Conduit.

BACKGROUND: Transcarotid artery revascularization (TCAR) is a hybrid technique with excellent initial outcomes. The technical success and safety of TCAR is heavily dependent on an anatomically suitable common carotid artery (CCA). Many patients do not meet anatomic criteria and therefore are not eligible for this therapy. We sought to extend the eligibility of TCAR to patients with unfavorable CCA anatomy via the adoption of a prosthetic arterial conduit. METHODS: A single-center retrospective study of patients with critical carotid artery stenosis who underwent TCAR via a prosthetic conduit between June 2019 and October 2021 was performed. All patients in the study were considered high-risk for carotid endarterectomy based on anatomic features, such as restenosis post-carotid endarterectomy and neck radiation. Unfavorable CCA anatomy was defined as a clavicle to carotid bifurcation distance <5 cm, a CCA diameter <6 mm, and/or significant atherosclerotic disease at the intended arterial access site. The primary outcome of interest was technical success. Secondary outcomes included perioperative complications, intermediate and long-term patency, intermediate and long-term stroke and/or mortality and in-hospital length of stay. Follow-up ranged from 1 to 29 months. RESULTS: Eight patients underwent 10 TCAR procedures via a prosthetic conduit. A total of 2 procedures (20%) were performed on female patients and 8 procedures (75%) were performed on male patients. The mean age was 65 years old (standard deviation 11 years). Technical success was 100%. The 30-day ipsilateral stroke rate was 0%. The 30-day patency was 90%. There was no re-exploration for hemorrhage and 30 day mortality was 0%. CONCLUSIONS: TCAR is an excellent option for carotid artery revascularization. Unfavorable CCA anatomy has limited its applicability. TCAR via a prosthetic conduit has the potential to expand eligibility for this promising therapy.

Current Status and Principles for the Treatment and Prevention of Diabetic Foot Ulcers in the Cardiovascular Patient Population: A Scientific Statement From the American Heart Association.

Despite the known higher risk of cardiovascular disease in individuals with type 2 diabetes, the pathophysiology and optimal management of diabetic foot ulcers (DFUs), a leading complication associated with diabetes, is complex and continues to evolve. Complications of type 2 diabetes, such as DFUs, are a major cause of morbidity and mortality and the leading cause of major lower extremity amputation in the United States. There has recently been a strong focus on the prevention and early treatment of DFUs, leading to the development of multidisciplinary diabetic wound and amputation prevention clinics across the country. Mounting evidence has shown that, despite these efforts, amputations associated with DFUs continue to increase. Furthermore, due to increasing patient complexity of management secondary to comorbid conditions, such as cardiovascular disease, the management of peripheral artery disease associated with DFUs has become increasingly difficult, and care delivery is often episodic and fragmented. Although structured, process-specific approaches exist at individual institutions for the management of DFUs in the cardiovascular patient population, there is insufficient awareness of these principles in the general medicine communities. Furthermore, there is growing interest in better understanding the mechanistic underpinnings of DFUs to better define personalized medicine to improve outcomes. The goals of this scientific statement are to provide salient background information on the complex pathogenesis and current management of DFUs in cardiovascular patients, to guide therapeutic and preventive strategies and future research directions, and to inform public policy makers on health disparities and other barriers to improving and advancing care in this expanding patient population.

Risk factors and consequences of wound complications following sartorius flap reconstruction.

OBJECTIVE: Groin wound complications are common following vascular surgery and can lead to significant patient morbidity. Sartorius muscle flap coverage may help to prevent vascular graft infection in the setting of wound dehiscence or infection. However, risk factors and consequences of wound complications following sartorius flap reconstruction remain incompletely investigated. METHODS: We retrospectively queried all patients who underwent sartorius flap reconstruction at a tertiary academic medical center. Data collected included patient demographics, medical comorbidities, surgical indication, index vascular procedure, and postoperative outcomes. The primary outcome was wound complication following sartorius flap procedure, which was defined as groin wound infection, dehiscence, or lymphocutaneous fistula. RESULTS: From 2012 to 2022, a total of 113 patients underwent sartorius flap reconstruction. Of these, 66 (58.4%) were performed after the development of a prior groin complication, and 47 (41.6%) were prophylactic. A total of 88 patients (77.9%) had a prosthetic bypass graft adjacent to the flap. Twenty-nine patients (25.7%) suffered a wound complication following sartorius flap reconstruction, including 14 (12.4%) with wound dehiscence, 13 (11.5%) with wound infection, and two (1.8%) with lymphocutaneous fistula. Patients with wound complications had a higher body mass index (28.8 vs 26.4 kg/m2; P =.03) and more frequently active smokers (86.2% vs 66.7%; P = .04). Additionally, patients with wound complications had a higher unplanned 30-day hospital readmission rates (72.4% vs 15.5%; P < .001), reintervention rates (75.9% vs 8.3%; P < .001), and re-do flap reconstruction rates (13.8% vs 2.4%; P = .02). On multivariable analysis, higher body mass index was independently associated with post-flap wound complications (adjusted odds ratio [aOR], 1.01; 95% confidence interval [CI], 1.001-1.03; P = .037). Consequently, wound complications were associated with both surgical reintervention (aOR, 35.4; 95% CI, 9.9-126.3; P < .001) and unplanned hospital readmission (aOR, 17.8; 95% CI, 5.9-54.1; P < .001). CONCLUSIONS: Sartorius flap reconstruction is an effective adjunct in facilitating wound healing of groin wounds. However, wound complications are common following sartorius flap reconstruction and may be associated with reintervention and unplanned hospital readmission. These data support the judicious and thoughtful utilization of sartorius flap procedures among high-risk patients.

Prosthetic Conduit Use Does Not Adversely Impact Outcomes after Open Repair of Popliteal Artery Aneurysms.

BACKGROUND: Single segment, greater saphenous vein (GSV) conduit is considered the optimal bypass conduit among patients undergoing bypass surgery for peripheral artery disease (PAD). While this data has been extrapolated to patients undergoing bypass for popliteal artery aneurysms (PAAs), the pathophysiology of PAA is inherently different when compared to PAD, and the impact of conduit type on long-term outcomes after open repair of PAA remains unclear. METHODS: A multicenter database of five regional hospitals was retrospectively reviewed for all patients with PAA undergoing open surgical repair. Data were collected on demographic information, operative details, medications, and postoperative outcomes. Kaplan-Meier curves were used to compare freedom from major adverse limb events (MALE) following GSV versus prosthetic bypass. Cox proportional hazards model was used to identify patient-level characteristics associated with MALE, which was defined as major ipsilateral limb amputation or reintervention for graft patency. RESULTS: From 1999 to 2020, a total of 101 patients with PAA underwent open exclusion and bypass surgery. Median follow-up period was 4.2 years (interquartile range, 1.3-7.4 years), and complete data were available for 99 (98.0%) patients. The majority of patients were male (99.0%) and Caucasian (93.9%). Only 11.1% of procedures were emergent, with the remainder (88.9%) being elective. All patients underwent medial exposure with a below-knee popliteal bypass target (100%). Bypass conduits included GSV (69.7%), prosthetic conduit (28.3%), and 2 (2.0%) alternative conduits (one spliced arm vein, one cryopreserved vein). Patients undergoing prosthetic bypass were older (72 vs. 66 years, P = 0.001) and had similar rates of medical comorbidities. Compared with the GSV group, patients with prosthetic conduits were more frequently placed on postoperative anticoagulation (60.7% vs. 23.2%, P < 0.001). Conduit type did not impact postoperative complication rates (P = NS each). MALE rates were low overall (19.2% at 2 years), and similar when stratified by conduit type (log rank P = 0.47). On multivariable analysis, emergent bypass was associated with MALE (hazard ratio [HR] 5.73, 95% confidence interval [CI] 2.07-15.85, P < 0.001). Prosthetic conduit usage (HR 1.00, 95% CI, 0.40-2.51, P = 0.99) and postoperative anticoagulation (HR 1.02, 95% CI 0.42-2.50, P = 0.97) were not associated with MALE. CONCLUSIONS: Open repair of PAA is associated with excellent long-term outcomes. Prosthetic bypass is a comparable alternative to autogenous conduit for below-knee popliteal bypass targets, and lack of suitable GSV should not prohibit open surgical repair when indicated.

Skeletal muscle regeneration failure in ischemic-damaged limbs is associated with pro-inflammatory macrophages and premature differentiation of satellite cells.

BACKGROUND: Chronic limb-threatening ischemia (CLTI), a severe manifestation of peripheral arterial disease (PAD), is associated with a 1-year limb amputation rate of approximately 15-20% and substantial mortality. A key feature of CLTI is the compromised regenerative ability of skeletal muscle; however, the mechanisms responsible for this impairment are not yet fully understood. In this study, we aim to delineate pathological changes at both the cellular and transcriptomic levels, as well as in cell-cell signaling pathways, associated with compromised muscle regeneration in limb ischemia in both human tissue samples and murine models of CLTI. METHODS: We performed single-cell transcriptome analysis of ischemic and non-ischemic muscle from the same CLTI patients and from a murine model of CLTI. In both datasets, we analyzed gene expression changes in macrophage and muscle satellite cell (MuSC) populations as well as differential cell-cell signaling interactions and differentiation trajectories. RESULTS: Single-cell transcriptomic profiling and immunofluorescence analysis of CLTI patient skeletal muscle demonstrated that ischemic-damaged tissue displays a pro-inflammatory macrophage signature. Comparable results were observed in a murine CLTI model. Moreover, integrated analyses of both human and murine datasets revealed premature differentiation of MuSCs to be a key feature of failed muscle regeneration in the ischemic limb. Furthermore, in silico inferences of intercellular communication and in vitro assays highlight the importance of macrophage-MuSC signaling in ischemia induced muscle injuries. CONCLUSIONS: Collectively, our research provides the first single-cell transcriptome atlases of skeletal muscle from CLTI patients and a murine CLTI model, emphasizing the crucial role of macrophages and inflammation in regulating muscle regeneration in CLTI through interactions with MuSCs.

Epigenetic Regulation of Angiogenesis in Peripheral Artery Disease.

Peripheral arterial disease (PAD) represents a global health concern with a rising prevalence attributed to factors such as obesity, diabetes, aging, and smoking. Among patients with PAD, chronic limb-threatening ischemia (CLTI) is the most severe manifestation, associated with substantial morbidity and mortality. While revascularization remains the primary therapy for CLTI, not all patients are candidates for such interventions, highlighting the need for alternative approaches. Impaired angiogenesis, the growth of new blood vessels, is a central feature of PAD, and despite decades of research, effective clinical treatments remain elusive. Epigenetics, the study of heritable changes in gene expression, has gained prominence in understanding PAD pathogenesis. Here, we explore the role of epigenetic regulation in angiogenesis within the context of PAD, with a focus on long non-coding RNAs and fibroblast-endothelial cell transdifferentiation. Additionally, we discuss the interplay between metabolic control and epigenetic regulation, providing insights into potential novel therapeutic avenues for improving PAD treatments. This review aims to offer a concise update on the application of epigenetics in angiogenesis and PAD research, inspiring further investigations in this promising field.

The Opportunity for Impactful Integration of Vascular and Podiatric Care.

BACKGROUND: The importance of collaboration between vascular and podiatric surgeons has been well-established. High-level partnerships are integral to the development of multidisciplinary programs and wound care centers, ultimately resulting in improved patient outcomes. This vascular-podiatric integration is not universal, however, and podiatric surgery may not be aligned within a vascular surgery division at many institutions. As one such institution, we reviewed our single-center experience in order to identify opportunities for the impactful integration of vascular-podiatric patient care. METHODS: Institutional electronic medical records were retrospectively reviewed for all procedures performed by vascular surgeons at a high volume, safety-net academic medical center. Data were collected on all primary and additional procedures, current procedural terminology (CPT) codes, case type (elective, urgent, emergent), surgeon specialty, and date/time of the procedures performed. CPT codes were linked to the Centers for Medicare & Medicaid Services' Physician Fee Schedule to estimate the work relative value unit (wRVU) per procedure. RESULTS: From 2018 to 2022, vascular surgeons performed a total of 12,206 operations, of which 1102 (9.9%) involved podiatric procedures. The most common vascular-performed podiatry procedures performed were toe amputations (38.1%, n = 420), transmetatarsal foot amputations (20.1%, n = 222), and ankle/foot debridement (16.2%, n = 178). Foot/ankle-specific procedures were identified as the primary procedure in 726 (65.9%) cases and as the adjunct procedure in 376 (34.1%) cases. A substantial proportion of podiatric procedures occurred on an urgent (n = 278, 25.2%) or emergent (n = 28, 2.5%) basis. A total of 163 (14.8%) cases occurred after hours (either before 0600 or after 1800), and 133 (12.1%) cases were performed on a holiday or weekend. Procedure-specific revenue included 4243.39 wRVU for primary procedures and 2108.08 wRVU for additional procedures performed. CONCLUSIONS: We report our single-center experience in which vascular surgeons provide a significant proportion of podiatric procedures. Our study underscores the potential for integrating podiatric surgeons within a vascular surgical division and presents opportunities for collaboration and enhanced patient care.

A national analysis of vascular surgery resident operative experience in peripheral artery disease.

BACKGROUND: Endovascular and hybrid interventions have played an increasingly prominent role in the treatment of peripheral arterial disease (PAD) in the past decade. This shift has prompted concerns about the adequacy of open surgical training for current surgical residents. Moreover, the recent Best Surgical Therapy in Patients With Critical Limb Ischemia trial has further emphasized the importance of open surgical techniques in the treatment of peripheral arterial disease. The purpose of this study was to examine national temporal trends in peripheral operative volume among integrated vascular surgery residents. METHODS: Data was obtained from the Accreditation Council for Graduate Medical Education national data reports for integrated vascular surgery residents. Case volumes for surgeon chief or surgeon junior cases were collected from academic years 2012 to 2013 and 2021 to 2022. Trends in case-mix and volume were evaluated using linear regression analysis. RESULTS: The mean total vascular operative volume increased from 851.2 to 914.3 cases among graduating chief residents, with an annual growth of 8.5 ± 1.7 cases/year (R2 = 0.77; P < .0001). Major vascular case volume also increased at a rate of 5.7 ± 1.2 cases/year (R2 = 0.74; P < .001). Among operative categories, peripheral cases were the most frequent (n = 232.2 [26.6%]) and demonstrated the greatest annual growth (+8.0 ± 0.8 cases/year, R2 = 0.93; P < .001). No changes were seen in volume of open peripheral cases, including suprainguinal bypass (+0.1 ± 0.2 cases/year; R2 = 0.08; P = .40) or femoropopliteal bypass procedures (-0.1 ± 0.2 cases/year; R2 = 0.17; P = .20). Infrapopliteal bypass (+0.4 ± 0.1 cases/year; R2 = 0.48; P = .006), iliac/femoral endarterectomy (+1.3 ± 0.2 cases/year; R2 = 0.82; P < .001), and leg thromboembolectomy (+0.4 ± 0.1 cases/year; R2 = 0.64; P < .001) all demonstrated annual growth. For endovascular peripheral cases, aortoiliac revascularization (+3.4 ± 0.3 cases/year; R2 = 0.94; P < .001), femoropopliteal revascularization (+5.4 ± 0.2 cases/year; R2 = 0.98; P < .001), and tibioperoneal revascularization (+2.0 ± 0.2 cases/year; R2 = 0.92; P < .001) all increased in volume. Lower extremity amputations, including above-knee amputation (+0.6 ± 0.2 cases/year; R2 = 0.65; P < .001) and below-knee amputation (+0.9 ± 0.2 cases/year; R2 = 0.72; P < .001) also demonstrated an increase in volume. CONCLUSIONS: Current graduating residents have higher open and endovascular case volumes for peripheral artery disease on a national level, despite the increasing popularity of endovascular techniques. Further studies are needed to identify how these trends may impact current vascular surgery milestones. These trends may also influence the rising interest in competency-based training programs.

A minimally invasive approach for management of pancreaticoduodenal artery and gastroduodenal artery aneurysm with celiac artery occlusion.

Management of pancreaticoduodenal artery aneurysms (PDAAs) and gastroduodenal artery aneurysms (GDAAs) with concomitant celiac occlusion represents a challenging clinical scenario. Here, we describe a 62-year-old female with PDAA and GDAA complicated by celiac artery occlusion due to median arcuate ligament syndrome. We used a staged, minimally invasive approach consisting of: (1) a robotic median arcuate ligament release; (2) endovascular celiac artery stenting; and (3) visceral aneurysm coiling. The findings from this case report represent a novel treatment strategy for the management of PDAA/GDAA with celiac artery compression secondary to median arcuate ligament syndrome.

First experience of evaluation of the impact of high-matrix size reconstruction in image quality in arterial CT runoff studies of the lower extremities.

OBJECTIVES: To determine whether image reconstruction with a higher matrix size improves image quality for lower extremity CTA studies. METHODS: Raw data from 50 consecutive lower extremity CTA studies acquired on two MDCT scanners (SOMATOM Flash, Force) in patients evaluated for peripheral arterial disease (PAD) were retrospectively collected and reconstructed with standard (512 × 512) and higher resolution (768 × 768, 1024 × 1024) matrix sizes. Five blinded readers reviewed representative transverse images in randomized order (150 total). Readers graded image quality (0 (worst)-100 (best)) for vascular wall definition, image noise, and confidence in stenosis grading. Ten patients' stenosis scores on CTA images were compared to invasive angiography. Scores were compared using mixed effects linear regression. RESULTS: Reconstructions with 1024 × 1024 matrix were ranked significantly better for wall definition (mean score 72, 95% CI = 61-84), noise (74, CI = 59-88), and confidence (70, CI = 59-80) compared to 512 × 512 (wall = 65, CI = 53 × 77; noise = 67, CI = 52 × 81; confidence = 62, CI = 52 × 73; p = 0.003, p = 0.01, and p = 0.004, respectively). Compared to 512 × 512, the 768 × 768 and 1024 × 1024 matrix improved image quality in the tibial arteries (wall = 51 vs 57 and 59, p < 0.05; noise = 65 vs 69 and 68, p = 0.06; confidence = 48 vs 57 and 55, p < 0.05) to a greater degree than the femoral-popliteal arteries (wall = 78 vs 78 and 85; noise = 81 vs 81 and 84; confidence = 76 vs 77 and 81, all p > 0.05), though for the 10 patients with angiography accuracy of stenosis grading was not significantly different. Inter-reader agreement was moderate (rho = 0.5). CONCLUSION: Higher matrix reconstructions of 768 × 768 and 1024 × 1024 improved image quality and may enable more confident assessment of PAD. CLINICAL RELEVANCE STATEMENT: Higher matrix reconstructions of the vessels in the lower extremities can improve perceived image quality and reader confidence in making diagnostic decisions based on CTA imaging. KEY POINTS: • Higher than standard matrix sizes improve perceived image quality of the arteries in the lower extremities. • Image noise is not perceived as increased even at a matrix size of 1024 × 1024 pixels. • Gains from higher matrix reconstructions are higher in smaller, more distal tibial and peroneal vessels than in femoropopliteal vessels.

Sex-based differences in outcomes after lower extremity bypass for chronic limb-threatening ischemia.

BACKGROUND AND AIMS: Lower extremity bypass surgery is an effective treatment option for patients with chronic limb-threatening ischemia (CLTI). Recent studies have suggested that sex-based differences may impact patient outcomes following lower extremity revascularization, however, results have been inconsistent. METHODS: In this multicenter analysis, we retrospectively identified all infrainguinal bypass procedures performed for CLTI from 2002 to 2021. Patients were separated into two groups based on sex. Primary outcomes were major limb amputation and reintervention for graft patency. RESULTS: Of 843 bypasses performed over the study period, 347 (41.2%) patients were female. Racial/ethnic distribution and medical comorbidities were similar across sex groups. Surgical indications and operative details were also similar between groups, including conduit type (49.9% autogenous), bypass target (65.4% infrageniculate), and concurrent endarterectomy (38.9%). Female and male patients had similar hospital length of stay (6 days [4-9] vs 6 days [4-9]), hospital readmission (25.6% vs 25.0%), and postoperative complications (p=NS each). Female patients had higher major amputation rates (10.1% vs 6.3%, p=0.04) after one year, whereas reintervention rates were similar between groups (26.2% vs 24.6%, p=NS). After accounting for patient factors, female sex (odds ratio [OR] 1.02 [1.00-1.04]), infrageniculate target (OR 1.02 [1.00-1.04]), and bypass for tissue loss (OR 1.02 [1.00-1.04]) were associated with major amputation after bypass (p<0.05 each). CONCLUSIONS: Female sex is associated with a small but significant increase major amputation after lower extremity bypass surgery for CLTI, despite similar clinical presentation, medical comorbidities, and operative details. These data support the increasingly recognized sex disparities in peripheral arterial disease.

Pro-inflammatory macrophages impair skeletal muscle regeneration in ischemic-damaged limbs by inducing precocious differentiation of satellite cells.

Chronic limb-threatening ischemia (CLTI), representing the end-stage of peripheral arterial disease (PAD), is associated with a one-year limb amputation rate of ∻15-20% and significant mortality. A key characteristic of CLTI is the failure of the innate regenerative capacity of skeletal muscle, though the underlying mechanisms remain unclear. Here, single-cell transcriptome analysis of ischemic and non-ischemic muscle from the same CLTI patients demonstrated that ischemic-damaged tissue is enriched with pro-inflammatory macrophages. Comparable results were also observed in a murine CLTI model. Importantly, integrated analyses of both human and murine data revealed premature differentiation of muscle satellite cells (MuSCs) in damaged tissue and indications of defects in intercellular signaling communication between MuSCs and their inflammatory niche. Collectively, our research provides the first single-cell transcriptome atlases of skeletal muscle from CLTI patients and murine models, emphasizing the crucial role of macrophages and inflammation in regulating muscle regeneration in CLTI through interactions with MuSCs.

Muscle progenitor cells are required for skeletal muscle regeneration and prevention of adipogenesis after limb ischemia.

Skeletal muscle injury in peripheral artery disease (PAD) has been attributed to vascular insufficiency, however evidence has demonstrated that muscle cell responses play a role in determining outcomes in limb ischemia. Here, we demonstrate that genetic ablation of Pax7+ muscle progenitor cells (MPCs) in a model of hindlimb ischemia (HLI) inhibited muscle regeneration following ischemic injury, despite a lack of morphological or physiological changes in resting muscle. Compared to control mice (Pax7WT), the ischemic limb of Pax7-deficient mice (Pax7Δ) was unable to generate significant force 7 or 28 days after HLI. A significant increase in adipose was observed in the ischemic limb 28 days after HLI in Pax7Δ mice, which replaced functional muscle. Adipogenesis in Pax7Δ mice corresponded with a significant increase in PDGFRα+ fibro/adipogenic progenitors (FAPs). Inhibition of FAPs with batimastat decreased muscle adipose but increased fibrosis. In vitro, Pax7Δ MPCs failed to form myotubes but displayed increased adipogenesis. Skeletal muscle from patients with critical limb threatening ischemia displayed increased adipose in more ischemic regions of muscle, which corresponded with fewer satellite cells. Collectively, these data demonstrate that Pax7+ MPCs are required for muscle regeneration after ischemia and suggest that muscle regeneration may be an important therapeutic target in PAD.

Study protocol of a randomized controlled trial of fistula vs. graft arteriovenous vascular access in older adults with end-stage kidney disease on hemodialysis: the AV access trial.

BACKGROUND: Treatment of end-stage kidney disease (ESKD) with hemodialysis requires surgical creation of an arteriovenous (AV) vascular access-fistula (AVF) or graft (AVG)-to avoid (or limit) the use of a central venous catheter (CVC). AVFs have long been considered the first-line vascular access option, with AVGs as second best. Recent studies have suggested that, in older adults, AVGs may be a better strategy than AVFs. Lacking evidence from well-powered randomized clinical trials, integration of these results into clinical decision making is challenging. The main objective of the AV Access Study is to compare, between the two types of AV access, clinical outcomes that are important to patients, physicians, and policy makers. METHODS: This is a prospective, multicenter, randomized controlled trial in adults ≥ 60 years old receiving chronic hemodialysis via a CVC. Eligible participants must have co-existing cardiovascular disease, peripheral arterial disease, and/or diabetes mellitus; and vascular anatomy suitable for placement of either type of AV access. Participants are randomized, in a 1:1 ratio, to a strategy of AVG or AVF creation. An estimated 262 participants will be recruited across 7 healthcare systems, with average follow-up of 2 years. Questionnaires will be administered at baseline and semi-annually. The primary outcome is the rate of CVC-free days per 100 patient-days. The primary safety outcome is the cumulative incidence of vascular access (CVC or AV access)-related severe infections-defined as access infections that lead to hospitalization or death. Secondary outcomes include access-related healthcare costs and patients' experiences with vascular access care between the two treatment groups. DISCUSSION: In the absence of studies using robust and unbiased research methodology to address vascular access care for hemodialysis patients, clinical decisions are limited to inferences from observational studies. The goal of the AV Access Study is to generate evidence to optimize vascular access care, based on objective, age-specific criteria, while incorporating goals of care and patient preference for vascular access type in clinical decision-making. TRIAL REGISTRATION: This study is being conducted in accordance with the tenets of the Helsinki Declaration, and has been approved by the central institutional review board (IRB) of Wake Forest University Health Sciences (approval number: 00069593) and local IRB of each participating clinical center; and was registered on Nov 27, 2020, at ClinicalTrials.gov (NCT04646226).

Preoperative Anemia is Associated with Poorer Postoperative Outcomes in Patients Undergoing Infrainguinal Bypass Surgery.

BACKGROUND: Preoperative anemia is an important, modifiable risk factor among surgical patients. However, data are scarce on the impact of preoperative anemia on postoperative outcomes after infrainguinal bypass. METHODS: In this multi-institutional analysis, data were retrospectively collected on all infrainguinal bypass procedures performed between 2010 and 2020. Patients were grouped by preoperative hemoglobin as per the National Cancer Institute anemia scale (mild, 10 g/dL-lower limit of normal; moderate, 8.0-9.9 g/dL; severe, 6.5-7.9 g/dL). Multivariable comparisons were performed using logistic regression analysis. RESULTS: A total of 492 patients underwent bypass for peripheral artery disease over the 10-year study period. Median preoperative hemoglobin was 11.0 g/dL (interquartile range 9.5-12.7) and median follow-up was 1.7 years. Preoperative anemia was prevalent among bypass patients (mild 52.4% [n = 258], moderate 26.4% [n = 130], and severe 5.1% [n = 25]). Women were more likely to have moderate (49.2% [women] vs. 50.8% [men]) or severe anemia (52.0% [women] vs. 48.0% [men]) compared with normal hemoglobin (17.7% [women] vs. 82.3% [men]) (P < 0.001). Patients with preoperative anemia were more likely to present with tissue loss (22.8% [normal] vs. 47.7% [moderate] vs. 52.0% [severe], P = 0.01). Bypass target and conduit types were similar between groups. Anemic patients had longer median hospital length of stay compared with nonanemic patients (4 days [normal] vs. 5 days [mild] vs. 6 days [moderate] vs. 7 days [severe], P < 0.001). Postoperative mortality at 30 days was similar across anemia groups (2.5% [normal] vs. 4.6% [moderate] vs. 8.0% [severe], P = 0.23). On multivariable analysis, however, postoperative mortality was independently associated with severe anemia (odds ratio 7.5 [1.2-48.8], P = 0.04) and male gender (odds ratio 7.5 [1.2-26.4], P = 0.03). CONCLUSIONS: Preoperative anemia is common among patients undergoing infrainguinal bypass surgery and is an independent risk factor for postoperative mortality. Future investigation is needed to determine whether correction of anemia improves postoperative outcomes in these high-risk patients.

A Multidimensional Bioinformatic Platform for the Study of Human Response to Surgery.

OBJECTIVE: To design and establish a prospective biospecimen repository that integrates multi-omics assays with clinical data to study mechanisms of controlled injury and healing. BACKGROUND: Elective surgery is an opportunity to understand both the systemic and focal responses accompanying controlled and well-characterized injury to the human body. The overarching goal of this ongoing project is to define stereotypical responses to surgical injury, with the translational purpose of identifying targetable pathways involved in healing and resilience, and variations indicative of aberrant peri-operative outcomes. METHODS: Clinical data from the electronic medical record combined with large-scale biological data sets derived from blood, urine, fecal matter, and tissue samples are collected prospectively through the peri-operative period on patients undergoing 14 surgeries chosen to represent a range of injury locations and intensities. Specimens are subjected to genomic, transcriptomic, proteomic, and metabolomic assays to describe their genetic, metabolic, immunologic, and microbiome profiles, providing a multidimensional landscape of the human response to injury. RESULTS: The highly multiplexed data generated includes changes in over 28,000 mRNA transcripts, 100 plasma metabolites, 200 urine metabolites, and 400 proteins over the longitudinal course of surgery and recovery. In our initial pilot dataset, we demonstrate the feasibility of collecting high quality multi-omic data at pre- and postoperative time points and are already seeing evidence of physiologic perturbation between timepoints. CONCLUSIONS: This repository allows for longitudinal, state-of-the-art geno-mic, transcriptomic, proteomic, metabolomic, immunologic, and clinical data collection and provides a rich and stable infrastructure on which to fuel further biomedical discovery.

HiCAR is a robust and sensitive method to analyze open-chromatin-associated genome organization.

The long-range interactions of cis-regulatory elements (cREs) play a central role in gene regulation. cREs can be characterized as accessible chromatin sequences. However, it remains technically challenging to comprehensively identify their spatial interactions. Here, we report a new method HiCAR (Hi-C on accessible regulatory DNA), which utilizes Tn5 transposase and chromatin proximity ligation, for the analysis of open-chromatin-anchored interactions with low-input cells. By applying HiCAR in human embryonic stem cells and lymphoblastoid cells, we demonstrate that HiCAR identifies high-resolution chromatin contacts with an efficiency comparable with that of in situ Hi-C over all distance ranges. Interestingly, we found that the "poised" gene promoters exhibit silencer-like function to repress the expression of distal genes via promoter-promoter interactions. Lastly, we applied HiCAR to 30,000 primary human muscle stem cells and demonstrated that HiCAR is capable of analyzing chromatin accessibility and looping using low-input primary cells and clinical samples.

Underutilization of Guideline-based Abdominal Aortic Aneurysm Screening in an Academic Health System.

OBJECTIVES: The US Preventive Services Task Force (USPSTF) recommends a 1 time screening for AAA with ultrasonography in men aged 65-75 who have ever smoked. Our objectives were to identify the AAA screening rates in a large academic health system and assess factors associated with receipt of screening. METHODS: Data were extracted from electronic health records from the Duke University Health System and the US Census Bureau. Index screening eligibility date was defined as the 65th birthdate for male patients with a history of smoking. Patients with an index screening eligibility date between January 1, 2016 and December 31, 2018 were included in the study population and followed through December 31, 2019. Screened patients were identified by procedure codes for ultrasonography, CT or MRI. RESULTS: Among 6,682 eligible patients who turned 65 years old between January 1, 2016 and December 31, 2018 with at least 1 year of follow-up, only 463 (6.9%) received AAA screening during the study period. The odds of receiving AAA screening within 1 year of index eligibility were 27% lower for Black patients compared to whites [OR = 0.73, 95% CI (0.58,0.93)]. Patients who visited a PCP or were diagnosed with hypertension had 75% and 41% greater odds of receiving screening, respectively [OR 1.75, 95% CI (1.36,2.25)] and [OR 1.41 95% CI (1.11,1.80)] compared with patients who did not. Among 4,580 men with 2 years of follow-up, AAA screening rate increased to 13.0%. Patients who visited a PCP had 64% greater odds of receiving screening within 2 years of index eligibility compared to those who did not [OR = 1.64, 95% CI (1.30,2.06)]. CONCLUSIONS: Screening for AAA per USPSTF guidelines is underutilized with evidence of a racial disparity. Although PCP visit is the most consistent predictor of screening, provider screening rates are low.