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Extracellular vesicle (EV)-based regenerative therapy has shown promising results in preclinical models of renal disease and might be useful for patients with several forms of chronic kidney disease. However, individuals with chronic kidney disease often present with comorbidities, including obesity, hypertension, diabetes, or even metabolic syndrome, which may alter the endogenous characteristics and impair the reparative capacity of stem cells and their daughter EVs. This brief review summarizes evidence of alterations in the morphology, cargo, and function of mesenchymal stem cells and mesenchymal stem cell-derived EVs in the face of cardiovascular disease. We further discuss the important ramifications for their use in patients with kidney disease.

Abstract Background: Currently, low molecular weight heparin is the guideline endorsed treatment of patients with cancer associated venous thromboembolism (VTE). While apixaban is approved for the treatment of acute VTE, there are limited data supporting its use in cancer patients. Methods: Patients with cancer associated acute VTE were randomly assigned to receive either apixaban 10 mg twice daily for 7 days followed by 5 mg twice daily or subcutaneous dalteparin (200 IU/kg for 1 month followed by 150 IU/kg once daily) for 6 months. The primary outcome was major bleeding. Secondary outcomes included VTE recurrence and a composite of major plus clinically relevant non-major bleeding. Results: Of the 300 patients who underwent randomization, 287 were included in the primary analysis. Of these, metastatic disease was present in 65.5% of subjects and 74% were receiving concurrent systemic cancer therapy. Colorectal, lung, pancreas, and breast cancers were the four most prevalent cancer types. Major bleeding occurred in 0 of the 142 patients (0%) in the apixaban group as compared with 3 of the 145 patients (2.1%) in the dalteparin group (p=0.9956). Recurrent VTE occurred in 5 patients (3.4%) in the apixaban group and 20 patients (14.1%) in the dalteparin group (difference in risk -10.7 percentage points) with a Hazard Ratio (HR) 0.26, (95% CI, 0.09 - 0.80, p = 0.0182). Major plus clinically relevant non-major bleeding were similar at 9% for both groups. There were no mortality differences comparing apixaban (15.9%) and dalteparin (10.6%) groups at 6 months (HR 1.36, 95% CI 0.79 - 2.35). Monthly quality of life surveys favored apixaban therapy for many measures including: concern for excess bruising, stress, irritation, burden of delivery, and overall satisfaction with anticoagulant therapy (p<0.05). Monthly bruising questionnaire favored apixaban at each interval (p<0.002). Conclusions: Oral apixaban therapy was associated with very low rates of bleeding and significantly lower VTE recurrence with superior quality of life outcome measures compared to parenteral dalteparin in the treatment of cancer associated VTE. These data support the clinical utility of apixaban for the acute treatment of VTE in this patient population. Table. Table. Disclosures No relevant conflicts of interest to declare.

Background: Scattered tubular-like cells (STCs) proliferate and differentiate to support neighboring injured renal tubular cells during recovery from insults. Renal artery stenosis (RAS) induces renal ischemia and hypertension and leads to loss of kidney function, but whether RAS alters renal endogenous repair mechanisms, such as STCs, remains unknown. We hypothesize that RAS in swine modifies the messenger RNA (mRNA) profile of STCs, blunting their in vitro reparative capacity. Methods: CD24+/CD133+ STCs were isolated from pig kidneys after 10-weeks of RAS or sham (n = 3 each) and their gene cargo analyzed using high-throughput mRNAseq. Expression profiles for upregulated and downregulated mRNAs in RAS-STCs were functionally interpreted by gene ontology analysis. STC activation was assessed by counting the total number of STCs in pig kidney sections using flow cytometry, whereas cell proliferation was assessed in vitro. Results: Of all expressed genes, 1430 genes were upregulated and 315 downregulated in RAS- versus Normal-STCs. Expression of selected candidate genes followed the same fold change directions as the mRNAseq findings. Genes upregulated in RAS-STCs were involved in cell adhesion, extracellular matrix remodeling, and kidney development, whereas those downregulated in RAS-STCs are related to cell cycle and cytoskeleton. The percentage of STCs from dissociated kidney cells was higher in RAS versus Normal pigs, but their proliferation rate was blunted. Conclusions: Renal ischemia and hypertension in swine induce changes in the mRNA profile of STCs, associated with increased STC activation and impaired proliferation. These observations suggest that RAS may alter the reparative capacity of STCs.

Abstract Abstract 491 Introduction: Chronically-anticoagulated patients with active cancer (Ca) often require temporary interruption of warfarin for an invasive diagnostic or therapeutic procedure. While such patients may be at increased risk for periprocedural thromboembolism and bleeding, there are virtually no estimates of these outcomes among Ca patients or the most appropriate periprocedural anticoagulation management. The aims of this study were to estimate rates of these outcomes among Ca patients and to test active cancer and “bridging” low molecular weight heparin (LMWH) as potential predictors of these outcomes. Patients and Methods: In a retrospective cohort study, all chronically-anticoagulated patients referred to the Mayo Clinic Thrombophilia Center for periprocedural anticoagulation management over the 11-year period, 1997-2007, were followed forward in time for the outcomes of venous and arterial thromboembolism (VTE; ATE), major bleeding and vital status within 3 months of consultation. Warfarin was stopped 4-5 days prior to the procedure and patients received bridging LMWH according to the estimated risk of thromboembolism and bleeding. All outcome events were centrally adjudicated using pre specified criteria. Results: The total cohort (n=2517) included 500 patients with Ca. Chronic anticoagulation indications included prior VTE (n=1033), mechanical heart valve (n=669), atrial fibrillation (n=530) and other (mainly vascular bypass; n=285). 65% and 64% of patients with and without Ca received bridging LMWH, respectively. Prior VTE was more common among Ca patients compared to those without CA, both in the bridged (56% vs 37%; p<0.001) and the non-bridged (48% vs 39%; p<0.05) groups. The 3 month rate for the composite of VTE, ATE or bleeding was higher among Ca patients compared to patients without Ca (5% vs 2%; p=0.004) due to higher post procedure rates of VTE (1% vs 0.2%; p<0.001) and major bleeding (4% vs 1.7%; p=0.009); the post procedure ATE rates were low in both groups (0.40% vs 0.45%). For the entire cohort, patients receiving bridging LMWH had a significantly higher rate of post procedure bleeding (5% vs 1%; p<0.05). Finally, there were significantly more deaths in Ca patients compared to non-Ca patients (5% vs. 1%; p<0.001). Conclusions: The three-month rates of VTE, major bleeding and death among patients with Ca in whom anticoagulation is temporarily interrupted for an invasive procedure is significantly higher than in patients without Ca, especially the major bleeding rate. Use of heparin increases this rate even farther, suggesting that bridging should be used with caution in patients with active cancer. Disclosures: No relevant conflicts of interest to declare.

Abstract Prompted by the activity of lenalidomide (Revlimid®) in pts with chronic idiopathic myelofibrosis (CIMF), we sought to evaluate the safety and efficacy of the combination of lenalidomide and prednisone in a phase II study for pts with CIMF. The rationale for this combination is that the anti-angiogenic and anti-TNFa effects of lenalidomide may be potentiated by the effects of prednisone to reduce marrow fibrosis and improve hematopoiesis in CIMF. Initial therapy consisted of lenalidomide 10 mg/d (dose level [DL] 0) on days 1–21 of a 28–day cycle for 6 cycles, in combination with prednisone 30 mg/d orally during cycle 1, 15 mg/d orally during cycle 2, and 15 mg/d every other day during cycle 3. The lenalidomide dose could be reduced to 5 mg/d (DL -1) or to 5 mg/d every other day (DL -2), or increased to 15 mg/d (DL +1) or 20 mg/d (DL +2) depending upon toxicity or lack of response, respectively. A total of 40 pts (23 male, 17 female) have been enrolled. The median age was 62 years (range, 41–86), time from CIMF diagnosis to the study treatment 10 months (range, 0–269), WBC count 87x109/L (range, 1.1–89), hemoglobin 9.8 g/dL (range, 7.8–17.3), platelets 137x109/L (range, 8–1183). Pts had received a median of 1 prior therapy (range 0–4): hydroxyurea (HU; n=14), anagrelide (AG; n=4), azacitidine (n=6), steroids (n=5), thalidomide (n=4), and interferon (n=3). Ten (25%) pts had not received any prior therapy. JAK2 V617F mutation was detected in 18 (50%) of 36 tested pts and 20 (50%) of 40 had abnormal cytogenetics. A total of 260 cycles have been administered. All 40 pts are evaluable for response and toxicity. Responses have been observed in 12 (30%) pts, including complete response (CR) in 2 (normal blood counts and <5% bone marrow blasts, off HU, AG, growth factors, and no transfusions); partial response (PR) in 7 (at least 2 of the following: Hb increase by ≥2 g/dL, 50% increase in platelets, decrease of bone marrow blasts or organomegaly by ≥50%, normalization of WBC count without blasts, or reduction in bone marrow fibrosis; off HU, AG, growth factors, and transfusion independence); and hematologic improvement (HI) in 3 (at least 2 of the following: decrease by ≥25% of pretreatment leukocytosis, splenomegaly, or marrow blasts, or increase of Hb by ≥1g/dl without growth factor or transfusion support or platelets by ≥25%; off HU, AG, growth factors). Median time to response was 12 weeks (range, 2–32). Responses have been sustained for a median of 15 wks (range, 5–36) and are ongoing in all 12 responders. Overall, 21 (53%) pts experienced grade 3–4 toxicity, being the most frequent neutropenia, anemia, musculoskeletal pain, and fatigue. Twenty-four (60%) pts have required dose reduction to DL -1, of which 5 (12.5%) further reduced to DL -2. One (2.5%) pt dose-escalated to DL +1, while 15 (25%) remained at DL 0. Twenty-one (53%) pts discontinued lenalidomide due to: lack of response (n=8), pt’s decision (n=7), grade 3–4 toxicity (n=5), and poor compliance (n=1). No deaths or transformation to acute myeloid leukemia occurred. In summary, the combination of lenalidomide and prednisone is an active and generally well-tolerated regimen for pts with CIMF. Longer follow-up is warranted to evaluate the durability of ongoing responses. Updated results will be presented at the meeting.

Abstract Introduction Cancer associated thrombosis is the second most common cause of mortality among patients with malignancy. While preventive low molecular weight heparin is effective in preventing venous thromboembolism (VTE), lack of agreement on risk stratification methods have precluded its widespread use. The most studied VTE prediction tool is the Khorana score, but it does not capitalize on the use of novel biomarkers. We aimed to evaluate the value of biomarkers in prediction of VTE among patients with active cancer receiving outpatient chemotherapy. Methods We prospectively collected pre-chemotherapy blood samples on adult patients with solid organ tumors. We excluded patients on anticoagulation and those unable or unwilling to consent. Along with demographics and cancer specific variables, potential novel predictors of VTE were selected a priori and included: coated platelets (CP), D dimer (DD), protein C (PC), fibrin monomers (FM), mean platelet volume (MPV), platelet microparticles (PMP). Type of cancer was grouped according to the Khorana score (Very high risk: Stomach, Pancreas; High risk: Lung, Gynecologic, Bladder, Testicular; Low/Moderate risk: all other sites). VTE events were adjudicated at 6 months of follow up. For all statistical analyses we used SAS 9.2 (SAS Institute Inc., Cary, NC, USA). A p value of <0.05 was considered as statistically significant. We only performed univariate analysis at this point of our study due to the stage of recruitment and period of follow-up. Results We have recruited a total of 101 patients (mean + standard deviation age 59.7+11 years, 68% female), 20% of the 75 patients with complete follow up have developed a VTE. We found no significant association between the incidence of VTE and age, gender, or baseline Khorana score. The variables associated with incident VTE were: BMI (odds ratio [OR] 8.5 for BMI<25 kg/m2, p<0.001), type of cancer (OR 14.5 for very high risk compared to high risk, p<0.01) and protein C (OR 3.3 for protein C<110ug/mL the lowest tertile, p=0.05). The rest of the tested potential biomarkers did not have a strong association with incident VTE in the current analysis (Table). Twenty percent of the patients were on aspirin and none of them developed VTE compared to 23% of those not taking aspirin who developed VTE, (p=0.2). Conclusion Pre Chemotherapy level of Protein C is a potential biomarker for the incidence of VTE. We confirm that cancer type and BMI are predictors of cancer associated VTE. In addition, lower BMI is not usually recognized as a potential predictor of VTE in other prediction scores. We were underpowered to detect differences in the VTE incidence according to Khorana score. Finally, aspirin may have a role in outpatient cancer associated VTE prevention and deserves further investigation. Disclosures: Tafur: Stago Diagnostica: Research Funding. Rathbun:Stago Diagnostica: Research Funding.

Abstract The term sarcopenia was introduced in 1988. The original definition was a “muscle loss” of the appendicular muscle mass in the older people as measured by dual energy x‐ray absorptiometry (DXA). In 2010, the definition was altered to be low muscle mass together with low muscle function and this was agreed upon as reported in a number of consensus papers. The Society of Sarcopenia, Cachexia and Wasting Disorders supports the recommendations of more recent consensus conferences, i.e. that rapid screening, such as with the SARC‐F questionnaire, should be utilized with a formal diagnosis being made by measuring grip strength or chair stand together with DXA estimation of appendicular muscle mass (indexed for height2). Assessments of the utility of ultrasound and creatine dilution techniques are ongoing. Use of ultrasound may not be easily reproducible. Primary sarcopenia is aging associated (mediated) loss of muscle mass. Secondary sarcopenia (or disease‐related sarcopenia) has predominantly focused on loss of muscle mass without the emphasis on muscle function. Diseases that can cause muscle wasting (i.e. secondary sarcopenia) include malignant cancer, COPD, heart failure, and renal failure and others. Management of sarcopenia should consist of resistance exercise in combination with a protein intake of 1 to 1.5 g/kg/day. There is insufficient evidence that vitamin D and anabolic steroids are beneficial. These recommendations apply to both primary (age‐related) sarcopenia and secondary (disease related) sarcopenia. Secondary sarcopenia also needs appropriate treatment of the underlying disease. It is important that primary care health professionals become aware of and make the diagnosis of age‐related and disease‐related sarcopenia. It is important to address the risk factors for sarcopenia, particularly low physical activity and sedentary behavior in the general population, using a life‐long approach. There is a need for more clinical research into the appropriate measurement for muscle mass and the management of sarcopenia. Accordingly, this position statement provides recommendations on the management of sarcopenia and how to progress the knowledge and recognition of sarcopenia.

Scattered tubular-like cells (STCs) contribute to repair neighboring injured renal tubular cells. Mitochondria mediate STC biology and function but might be injured by the ambient milieu. We hypothesized that the microenviroment induced by the ischemic and metabolic components of renovascular disease impairs STC mitochondrial structure and function in swine, which can be attenuated with mitoprotection. CD24+/CD133+STCs were quantified in pig kidneys after 16 wk of metabolic syndrome (MetS) or lean diet (Lean) with or without concurrent renal artery stenosis (RAS) ( n = 6 each). Pig STCs were isolated and characterized, and mitochondrial structure, membrane potential, and oxidative stress were assessed in cells untreated or incubated with the mitoprotective drug elamipretide (1 nM for 6 h). STC-protective effects were assessed in vitro by their capacity to proliferate and improve viability of injured pig tubular epithelial cells. The percentage of STCs was higher in MetS, Lean + RAS, and MetS + RAS kidneys compared with Lean kidneys. STCs isolated from Lean + RAS and MetS + RAS pigs showed mitochondrial swelling and decreased matrix density, which were both restored by mitoprotection. In addition, mitochondrial membrane potential and ATP production were reduced and production of reactive oxygen species elevated in MetS, Lean + RAS, and MetS + RAS STCs. Importantly, mitoprotection improved mitochondrial structure and function as well as the capacity of MetS + RAS STCs to repair injured tubular cells in vitro. Renovascular disease in swine is associated with a higher prevalence of STCs but induces structural and functional alterations in STC mitochondria, which impair their reparative potency. These observations suggest a key role for mitochondria in the renal reparative capacity of STCs.

AbstractIntroduction:Patients with end‐stage renal disease (ESRD) experience frequent hemodialysis (HD) complications. Intradialytic hypotension (IDH) is a common complication presenting in approximately between 20 and 50% of HD sessions. Available interventions such as volume replacement or vasoactive medications are associated with significant side effects.Intermittent pneumatic compression (IPC) has been proposed as a feasible intervention for the prevention of IDH, treatment of peripheral arterial disease and venous ulcers. These devices apply intermittent pressure to the legs improving arterial blood flow, mobilization of pooled blood with an increase in venous return increasing the effective circulatory volume.Our goal was to identify the published clinical evidence on whether IPC has a circulatory benefit and is it well‐tolerated among patients receiving HD.Methods:We conducted a systematic review to identify studies assessing the efficacy and safety of IPC in patients with ESRD. Our primary outcome was IDH. Secondary outcomes such as HD comfort, ultrafiltration volume, and physical activity were collected. No restrictions where used and we included all observational and interventional studies. Two reviewers performed screening and study quality assessment.Findings:We included seven studies. Out of the seven studies, five addressed IDH, and the rest were included for secondary outcomes such as physical capacity and HD comfort. In one randomized crossover trial comparing exercise against IPC, 21 patients were randomized to 3 different arms (no intervention, cycling, IPC) a decrease in the rates of IDH with IPC was described (43%, 38%, and 24% respectively P = 0.014). The smaller studies corroborated these results. All studies where at high risk of bias.Discussion:IPC might offer significant benefits for patients undergoing HD not limited to prevention of IDH but also improvement of hemodialysis comfort and physical capacity. However, our results should be interpreted in the context of its limitations.