Bioprosthetic Total Artificial Heart in Autoregulated Mode Is Biologically Hemocompatible: Insights for Multimers of von Willebrand Factor.

BACKGROUND: Carmat bioprosthetic total artificial heart (Aeson; A-TAH) is a pulsatile and autoregulated device. The aim of this study is to evaluate level of hemolysis potential acquired von Willebrand syndrome after A-TAH implantation. METHODS: We examined the presence of hemolysis and acquired von Willebrand syndrome in adult patients receiving A-TAH support (n=10) during their whole clinical follow-up in comparison with control subjects and adult patients receiving Heartmate II or Heartmate III support. We also performed a fluid structure interaction model coupled with computational fluid dynamics simulation to evaluate the A-TAH resulting shear stress and its distribution in the blood volume. RESULTS: The cumulative duration of A-TAH support was 2087 days. A-TAH implantation did not affect plasma free hemoglobin over time, and there was no association between plasma free hemoglobin and cardiac output or beat rate. For VWF (von Willebrand factor) evaluation, A-TAH implantation did not modify multimers profile of VWF in contrast to Heartmate II and Heartmate III. Furthermore, fluid structure interaction coupled with computational fluid dynamics showed a gradually increase of blood damage according to increase of cardiac output (P<0.01), however, the blood volume fraction that endured significant shear stresses was always inferior to 0.03% of the volume for both ventricles in all regimens tested. An inverse association between cardiac output, beat rate, and high-molecular weight multimers ratio was found. CONCLUSIONS: We demonstrated that A-TAH does not cause hemolysis or AWVS. However, relationship between HMWM and cardiac output depending flow confirms relevance of VWF as a biological sensor of blood flow, even in normal range.

Human Aortic Valve Interstitial Cells Display Proangiogenic Properties During Calcific Aortic Valve Disease.

OBJECTIVE: The study's aim was to analyze the capacity of human valve interstitial cells (VICs) to participate in aortic valve angiogenesis. Approach and Results: VICs were isolated from human aortic valves obtained after surgery for calcific aortic valve disease and from normal aortic valves unsuitable for grafting (control VICs). We examined VIC in vitro and in vivo potential to differentiate in endothelial and perivascular lineages. VIC paracrine effect was also examined on human endothelial colony-forming cells. A pathological VIC (VICp) mesenchymal-like phenotype was confirmed by CD90+/CD73+/CD44+ expression and multipotent-like differentiation ability. When VICp were cocultured with endothelial colony-forming cells, they formed microvessels by differentiating into perivascular cells both in vivo and in vitro. VICp and control VIC conditioned media were compared using serial ELISA regarding quantification of endothelial and angiogenic factors. Higher expression of VEGF (vascular endothelial growth factor)-A was observed at the protein level in VICp-conditioned media and confirmed at the mRNA level in VICp compared with control VIC. Conditioned media from VICp induced in vitro a significant increase in endothelial colony-forming cell proliferation, migration, and sprouting compared with conditioned media from control VIC. These effects were inhibited by blocking VEGF-A with blocking antibody or siRNA approach, confirming VICp involvement in angiogenesis by a VEGF-A dependent mechanism. CONCLUSIONS: We provide here the first proof of an angiogenic potential of human VICs isolated from patients with calcific aortic valve disease. These results point to a novel function of VICp in valve vascularization during calcific aortic valve disease, with a perivascular differentiation ability and a VEGF-A paracrine effect. Targeting perivascular differentiation and VEGF-A to slow calcific aortic valve disease progression warrants further investigation.

Strength Training: In Search of Optimal Strategies to Maximize Neuromuscular Performance.

Training with low-load exercise performed under blood flow restriction can augment muscle hypertrophy and maximal strength to a similar extent as the classical high-load strength training method. However, the blood flow restriction method elicits only minor neural adaptations. In an attempt to maximize training-related gains, we propose using other protocols that combine high voluntary activation, mechanical tension, and metabolic stress.

Efficacy of a new strength training design: the 3/7 method.

AIM: This study investigated the efficacy of a new strength training method on strength gain, hypertrophy, and neuromuscular fatigability. METHODS: The training exercise consisted of elbow flexion against a load of ~ 70% of one repetition maximal (1RM). A new method (3/7 method) consisting of five sets of an increasing number of repetitions (3 to 7) during successive sets and brief inter-set intervals (15 s) was repeated two times after 150 s of recovery and compared to a method consisting of eight sets of six repetitions with an inter-set interval of 150 s (8 × 6 method). Subjects trained two times per week during 12 weeks. Strength gain [1RM load and maximal isometric voluntary contraction (MVC)], EMG activity of biceps brachii and brachioradialis, as well as biceps' brachii thickness were measured. Change in neuromuscular fatigability was assessed as the maximal number of repetitions performed at 70% of 1RM before and after training. RESULTS: Both 3/7 and 8 × 6 methods increased 1RM load (22.2 ± 7.4 and 12.1 ± 6.6%, respectively; p < 0.05) and MVC force (15.7 ± 8.2 and 9.5 ± 9.5%; p < 0.05) with a greater 1RM gain (p < 0.05) for the 3/7 method. Normalized (%Mmax) EMG activity of elbow flexors increased (p < 0.05) similarly (14.5 ± 23.2 vs. 8.1 ± 20.5%; p > 0.05) after both methods but biceps' brachii thickness increased to a greater extent (9.6 ± 3.6 vs. 5.5 ± 3.7%; p < 0.05) for the 3/7 method. Despite subjects performing more repetitions with the same absolute load after training, neuromuscular fatigability increased (p < 0.05) after the two training methods. CONCLUSION: The 3/7 method provides a better stimulus for strength gain and muscle hypertrophy than the 8 × 6 method.

The heart regulates the endocrine response to heart failure: cardiac contribution to circulating neprilysin.

Aims: Heart failure (HF) is accompanied by major neuroendocrine changes including the activation of the natriuretic peptide (NP) pathway. Using the unique model of patients undergoing implantation of the CARMAT total artificial heart and investigating regional differences in soluble neprilysin (sNEP) in patients with reduced or preserved systolic function, we studied the regulation of the NP pathway in HF. Methods and results: Venous blood samples from two patients undergoing replacement of the failing ventricles with a total artificial heart were collected before implantation and weekly thereafter until post-operative week 6. The ventricular removal was associated with an immediate drop in circulating NPs, a nearly total disappearance of circulating glycosylated proBNP and furin activity and a marked decrease in sNEP. From post-operative week 1 onwards, NP concentrations remained overall unchanged. In contrast, partial recoveries in glycosylated proBNP, furin activity, and sNEP were observed. Furthermore, while in patients with preserved systolic function (n = 6), sNEP concentrations in the coronary sinus and systemic vessels were similar (all P > 0.05), in patients with reduced left-ventricular systolic function, sNEP concentration, and activity were ∼three-fold higher in coronary sinus compared to systemic vessels (n = 21, all P < 0.0001), while the trans-pulmonary gradient was neutral (n = 5, P = 1.0). Conclusion: The heart plays a pivotal role as a regulator of the endocrine response in systolic dysfunction, not only by directly releasing NPs but also by contributing to circulating sNEP, which in turn determines the bioavailability of other numerous vasoactive peptides.

Feasibility of Bioengineered Tracheal and Bronchial Reconstruction Using Stented Aortic Matrices.

Importance: Airway transplantation could be an option for patients with proximal lung tumor or with end-stage tracheobronchial disease. New methods for airway transplantation remain highly controversial. Objective: To establish the feasibility of airway bioengineering using a technique based on the implantation of stented aortic matrices. Design, Setting, and Participants: Uncontrolled single-center cohort study including 20 patients with end-stage tracheal lesions or with proximal lung tumors requiring a pneumonectomy. The study was conducted in Paris, France, from October 2009 through February 2017; final follow-up for all patients occurred on November 2, 2017. Exposures: Radical resection of the lesions was performed using standard surgical techniques. After resection, airway reconstruction was performed using a human cryopreserved (-80°C) aortic allograft, which was not matched by the ABO and leukocyte antigen systems. To prevent airway collapse, a custom-made stent was inserted into the allograft. In patients with proximal lung tumors, the lung-sparing intervention of bronchial transplantation was used. Main Outcomes and Measures: The primary outcome was 90-day mortality. The secondary outcome was 90-day morbidity. Results: Twenty patients were included in the study (mean age, 54.9 years; age range, 24-79 years; 13 men [65%]). Thirteen patients underwent tracheal (n = 5), bronchial (n = 7), or carinal (n = 1) transplantation. Airway transplantation was not performed in 7 patients for the following reasons: medical contraindication (n = 1), unavoidable pneumonectomy (n = 1), exploratory thoracotomy only (n = 2), and a lobectomy or bilobectomy was possible (n = 3). Among the 20 patients initially included, the overall 90-day mortality rate was 5% (1 patient underwent a carinal transplantation and died). No mortality at 90 days was observed among patients who underwent tracheal or bronchial reconstruction. Among the 13 patients who underwent airway transplantation, major 90-day morbidity events occurred in 4 (30.8%) and included laryngeal edema, acute lung edema, acute respiratory distress syndrome, and atrial fibrillation. There was no adverse event directly related to the surgical technique. Stent removal was performed at a postoperative mean of 18.2 months. At a median follow-up of 3 years 11 months, 10 of the 13 patients (76.9%) were alive. Of these 10 patients, 8 (80%) breathed normally through newly formed airways after stent removal. Regeneration of epithelium and de novo generation of cartilage were observed within aortic matrices from recipient cells. Conclusions and Relevance: In this uncontrolled study, airway bioengineering using stented aortic matrices demonstrated feasibility for complex tracheal and bronchial reconstruction. Further research is needed to assess efficacy and safety. Trial Registration: clinicaltrials.gov Identifier: NCT01331863.

The Carmat Bioprosthetic Total Artificial Heart Is Associated With Early Hemostatic Recovery and no Acquired von Willebrand Syndrome in Calves.

OBJECTIVES: To determine hemostasis perturbations, including von Willebrand factor (VWF) multimers, after implantation of a new bioprosthetic and pulsatile total artificial heart (TAH). DESIGN: Preclinical study SETTING: Single-center biosurgical research laboratory. PARTICIPANTS: Female Charolais calves, 2-to-6 months old, weighing 102-to-122 kg. INTERVENTIONS: Surgical implantation of TAH through a mid-sternotomy approach. MEASUREMENTS AND MAIN RESULTS: Four of 12 calves had a support duration of several days (4, 4, 8, and 10 days), allowing for the exploration of early steps of hemostasis parameters, including prothrombin time; coagulation factor levels (II, V, VII+X, and fibrinogen); and platelet count. Multimeric analysis of VWF was performed to detect a potential loss of high-molecular weight (HMW) multimers, as previously described for continuous flow rotary blood pumps. Despite the absence of anticoagulant treatment administered in the postoperative phase, no signs of coagulation activation were detected. Indeed, after an immediate postsurgery decrease of prothrombin time, platelet count, and coagulation factor levels, most parameters returned to baseline values. HMW multimers of VWF remained stable either after initiation or during days of support. CONCLUSIONS: Coagulation parameters and platelet count recovery in the postoperative phase of the Carmat TAH (Camat SA, Velizy Villacoublay Cedex, France) implantation in calves, in the absence of anticoagulant treatment and associated with the absence of decrease in HMW multimers of VWF, is in line with early hemocompatibility that is currently being validated in human clinical studies.

First clinical use of a bioprosthetic total artificial heart: report of two cases.

BACKGROUND: The development of artificial hearts in patients with end-stage heart disease have been confronted with the major issues of thromboembolism or haemorrhage. Since valvular bioprostheses are associated with a low incidence of these complications, we decided to use bioprosthetic materials in the construction of a novel artificial heart (C-TAH). We report here the device characteristics and its first clinical applications in two patients with end-stage dilated cardiomyopathy. The aim of the study was to evaluate safety and feasibility of the CARMAT TAH for patients at imminent risk of death from biventricular heart failure and not eligible for transplant. METHODS: The C-TAH is an implantable electro-hydraulically actuated pulsatile biventricular pump. All components, batteries excepted, are embodied in a single device positioned in the pericardial sac after excision of the native ventricles. We selected patients admitted to hospital who were at imminent risk of death, having irreversible biventricular failure, and not eligible for heart transplantation, from three cardiac surgery centres in France. FINDINGS: The C-TAH was implanted in two male patients. Patient 1, aged 76 years, had the C-TAH implantation on Dec 18, 2013; patient 2, aged 68 years, had the implantation on Aug 5, 2014. The cardiopulmonary bypass times for C-TAH implantation were 170 min for patient 1 and 157 min for patient 2. Both patients were extubated within the first 12 postoperative hours and had a rapid recovery of their respiratory and circulatory functions as well as a normal mental status. Patient 1 presented with a tamponade on day 23 requiring re-intervention. Postoperative bleeding disorders prompted anticoagulant discontinuation. The C-TAH functioned well with a cardiac output of 4·8-5·8 L/min. On day 74, the patient died due to a device failure. Autopsy did not detect any relevant thrombus formation within the bioprosthesis nor the different organs, despite a 50-day anticoagulant-free period. Patient 2 experienced a transient period of renal failure and a pericardial effusion requiring drainage, but otherwise uneventful postoperative course. He was discharged from the hospital on day 150 after surgery with a wearable system without technical assistance. After 4 months at home, the patient suffered low cardiac output. A change of C-TAH was attempted but the patient died of multiorgan failure. INTERPRETATION: This preliminary experience could represent an important contribution to the development of total artificial hearts using bioprosthetic materials. FUNDING: CARMAT SA.

Can creatine supplementation form carcinogenic heterocyclic amines in humans?

There is a long-standing concern that creatine supplementation could be associated with cancer, possibly by facilitating the formation of carcinogenic heterocyclic amines (HCAs). This study provides compelling evidence that both low and high doses of creatine supplementation, given either acutely or chronically, does not cause a significant increase in HCA formation. HCAs detection was unrelated to creatine supplementation. Diet was likely to be the main factor responsible for HCAs formation after either placebo (n = 6) or creatine supplementation (n = 3). These results directly challenge the recently suggested biological plausibility for the association between creatine use and risk of testicular germ cell cancer. Creatine supplementation has been associated with increased cancer risk. In fact, there is evidence indicating that creatine and/or creatinine are important precursors of carcinogenic heterocyclic amines (HCAs). The present study aimed to investigate the acute and chronic effects of low- and high-dose creatine supplementation on the production of HCAs in healthy humans (i.e. 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx), 2-amino-(1,6-dimethylfuro[3,2-e]imidazo[4,5-b])pyridine (IFP) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx)). This was a non-counterbalanced single-blind crossover study divided into two phases, in which low- and high-dose creatine protocols were tested. After acute (1 day) and chronic supplementation (30 days), the HCAs PhIP, 8-MeIQx, IFP and 4,8-DiMeIQx were assessed through a newly developed HPLC-MS/MS method. Dietary HCA intake and blood and urinary creatinine were also evaluated. Out of 576 assessments performed (from 149 urine samples), only nine (3 from creatine and 6 from placebo) showed quantifiable levels of HCAs (8-MeIQx: n = 3; 4,8-DiMeIQx: n = 2; PhIP: n = 4). Individual analyses revealed that diet rather than creatine supplementation was the main responsible factor for HCA formation in these cases. This study provides compelling evidence that both low and high doses of creatine supplementation, given either acutely or chronically, did not cause increases in the carcinogenic HCAs PhIP, 8-MeIQx, IFP and 4,8-DiMeIQx in healthy subjects. These findings challenge the long-existing notion that creatine supplementation could potentially increase the risk of cancer by stimulating the formation of these mutagens.

Nitrate supplementation and human exercise performance: too much of a good thing?

PURPOSE OF REVIEW: Ergogenic supplements in sport events are widely used by popular and competitive athletes to enhance performance and reduce oxygen cost. Beetroot juice and nitrate salts have been increasingly used for the past 5-6 years. The present review discusses the scientific background, the efficiency and potential adverse effects of excessive nitrate supplementation. RECENT FINDINGS: There is clear evidence that nitrate from different food ingredients (such as beetroot juice and other vegetables) is converted into nitrite and possibly into nitric oxide, which may promote vasodilation, angiogenesis and mitochondrial biogenesis. The high affinity of nitric oxide towards different enzyme pathways inhibits excessive mitochondrial respiration and, therefore, tissue oxygen consumption. In addition, L-arginine supplements are proposed to stimulate nitric oxide synthesis in the endothelium. On the basis of these biochemical properties, nitrate supplementation has been suggested to athletes to enhance exercise performance. SUMMARY: The recent publications in human individuals based on L-arginine, beetroot juice or nitrate supplementation revealed either a minor positive effect or no systematic effect on exercise performance, especially in trained athletes. Of note, the sugar content of whole beetroot juice might induce a slightly more pronounced effect. Although reasonable intake of nitrate salts (up to 1 g/day) has no detrimental effect on kidney function, the risk and benefit of higher nitrate intake needs to be evaluated to define the optimal range of supplementation.

ß-Alanine supplementation slightly enhances repeated plyometric performance after high-intensity training in humans.

ß-Alanine (BA) supplementation has become an ergogenic aid amongst competitive athletes to augment intramuscular carnosine content, leading to higher buffer capacity and exercise performance. We investigated 27 regularly trained young males and females who were randomly allocated either to placebo (PL) or BA ingestion for 8 weeks. Every single day, BA or PL (4.0-5.6 g day(-1)) supplements were ingested by participants and associated with a strong plyometric high-intensity training (two sessions per week during the 8 weeks). Before and after training, maximal jump heights were recorded during squat jump (SJ) and countermovement jump (CMJ) and an index of fatigue was recorded as a mean height of 45 consecutive CMJ. Blood lactate was measured at rest, after completing the fatigue test and every 5 min thereafter up to 30 min recovery. After plyometric training, SJ and CMJ were increased, respectively, by 8.8 and 6.4 % in PL group and 9.9 and 11.0 % in BA group (p < 0.01, no difference between groups). Blood lactate reached a maximal value of 9.4 ± 1.6 mmol l(-1) in PL group, and 10.3 ± 1.3 mmol l(-1) in BA group, with a slight better performance in the fatigue test (+8.6 %, p ≤ 0.01) for BA group as compared to PL group. To conclude, 2-month ß-alanine supplementation resulted in a slight improvement of explosive force after 45 maximal consecutive jumps in young athletes. However, the practical adequacy of supplementation remains questionable in an active and healthy population.

Comprehensive annular and subvalvular repair of chronic ischemic mitral regurgitation improves long-term results with the least ventricular remodeling.

BACKGROUND: Undersized ring annuloplasty for ischemic mitral regurgitation (MR) is associated with variable results and >30% MR recurrence. We tested whether subvalvular repair by severing second-order mitral chordae can improve annuloplasty by reducing papillary muscle tethering. METHODS AND RESULTS: Posterolateral myocardial infarction known to produce chronic remodeling and MR was created in 28 sheep. At 3 months, sheep were randomized to sham surgery versus isolated undersized annuloplasty versus isolated bileaflet chordal cutting versus the combined therapy (n=7 each). At baseline, chronic myocardial infarction (3 months), and euthanasia (6.6 months), we measured left ventricular (LV) volumes and ejection fraction, wall motion score index, MR regurgitation fraction and vena contracta, mitral annulus area, and posterior leaflet restriction angle (posterior leaflet to mitral annulus area) by 2-dimensional and 3-dimensional echocardiography. All groups were comparable at baseline and chronic myocardial infarction, with mild to moderate MR (MR vena contracta, 4.6±0.1 mm; MR regurgitation fraction, 24.2±2.9%) and mitral annulus dilatation (P<0.01). At euthanasia, MR progressed to moderate to severe in controls but decreased to trace with ring plus chordal cutting versus trace to mild with chordal cutting alone versus mild to moderate with ring alone (MR vena contracta, 5.9±1.1 mm in controls, 0.5±0.08 with both, 1.0±0.3 with chordal cutting alone, 2.0±0.4 with ring alone; P<0.01). In addition, LV end-systolic volume increased by 108% in controls versus 28% with ring plus chordal cutting, less than with each intervention alone (P<0.01). In multivariate analysis, LV end-systolic volume and mitral annulus area most strongly predicted MR (r(2)=0.82, P<0.01). CONCLUSIONS: Comprehensive annular and subvalvular repair improves long-term reduction of both chronic ischemic MR and LV remodeling without decreasing global or segmental LV function at follow-up.

Sniff nasal inspiratory pressure in the longitudinal assessment of young Duchenne muscular dystrophy children.

Traditional measures of respiratory function in children with Duchenne muscular dystrophy (DMD) are based on maximal inspiratory pressure (PImax) and vital capacity (VC). Sniff nasal inspiratory pressure (SNIP) measurements are easily performed by young children with neuromuscular disorders. The clinical value of SNIP in the longitudinal assessment of respiratory weakness remains to be assessed. The objective of the present study was to assess longitudinally the changes in SNIP, PImax and VC with age in DMD children. We hypothesised that their longitudinal assessment would show an earlier decline in SNIP than VC. A 3-year, prospective follow-up, at 6-month intervals of, 33 steroid-naïve, 5-20-year-old DMD patients was analysed using a linear mixed model. SNIP measurements were reliable (within-session coefficient of variation 8%). SNIP and VC increased until 10.5 and 12.5 years of age, respectively, and declined thereafter, while PImax did not change with age. SNIP was an earlier marker of decline in respiratory muscle strength (at 10.5 years) than VC (at 12.5 years) in young DMD patients. SNIP longitudinal assessment is useful in the detection of inspiratory strength decline in young DMD patients when VC values remain within normal values and as an outcome measure in clinical trials for emerging therapeutics in young DMD patients from the age of 5 years.

Limitations of serum values to estimate glomerular filtration rate during exercise.

OBJECTIVE: Glomerular filtration rate (GFR) is part of routine medical practice for clinical assessment of kidney function in health and disease conditions, and is determined by measuring the clearance of creatinine (Cl-Crn) or estimated (eGFR) from equations using serum creatinine (Crn) or cystatin C (Cyst C). Crn and Cyst C methods obviate the need for urine collection but their reliability under non-resting conditions is uncertain. This study compared GFR determined by Cl-Crn, Crn and Cyst C methods under the conditions of rest and after exercise. METHODS: Twelve young male subjects performed a 30 min treadmill exercise at 80% of the maximal oxygen capacity. Venous blood samples and urine collections were collected before and after exercise and after recovery period. GFR rates were calculated from serum Crn and Cyst C equations, and Cl-Crn measured from serum and urine Crn output. Albumin was also determined for all samples. RESULTS: Under resting conditions, eGFR from Crn and Cyst C did not differ from Cl-Crn (p=0.39). Immediately after exercise, GFR decreased significantly, regardless of the method, but more so for Cl-Crn (-30.0%; p<0.05) compared with Crn (-18.2%) and Cyst C (-19.8%). After the recovery period, GFR determined by Cl-Crn was returned to initial values whereas Crn and Cyst C remained reduced. Although eGFR methods accurately estimate GFR at rest, those methods underestimated the change in GFR after acute exercise. CONCLUSIONS: These results indicate that exercise-induced changes in GFR should be determined by Cl-Crn method.

Natural evolution of weight status in Duchenne muscular dystrophy: a retrospective audit.

The life expectancy of patients with Duchenne muscular dystrophy (DMD) has increased. A cross-sectional study of DMD patients showed that 54 % of 13-year-old patients are obese and that 54 % of 18-year-old patients are underweight. We aimed to describe the natural evolution of weight status in DMD. This retrospective multi-centre audit collected body-weight measurements for seventy DMD patients born before 1992. The body-weight:age ratio (W:A) was used to evaluate weight status in reference to the Griffiths and Edwards chart. At the age of 13 years, 73 % were obese and 4 % were underweight. At maximal follow-up (age 15-26 years, mean 18·3 (sd 2·3) years), 47 % were obese and 34 % were underweight. Obesity at the age of 13 years was associated with later obesity, whereas normal weight status and underweight in 13-year-old patients predicted later underweight. A W:A ≥ 151 % in 13-year-old patients predicted later obesity, and a W:A ≤ 126·5 % predicted later underweight. Our audit provides the first longitudinal information about the spontaneous outcome of weight status in DMD. Patients (13 years old) with a W:A ≥ 151 % were more likely to become obese in late adolescence, but obesity prevented later underweight. These data suggest that mild obesity in 13-year-old DMD patients (W:A between 120 and 150 %) should not be discouraged because it prevents later underweight.

[The lung]. / Le poumon.

Lung transplantation is still the only curative treatment for end-stage pulmonary diseases. The results remain poor, however, because of the limited availability of lung donors, chronic rejection, and complications related to immunosuppressive therapy. The use of a bioartificial lung generated from autologous cells could offer a solution. We have demonstrated that in vivo epithelial and cartilage regeneration of the airways is feasible with the use of an aortic tissue matrix. Other studies show that in vitro and in vivo airway regeneration, respectively, can be obtained by using bio-engineering and heterotopic allograft implantation. A more complex challenge is the creation of an artificial lung Indeed, this would require the use of an elastic matrix that can promote regeneration of the different lung components (airways, alveoli, vessels) over a large surface area, thus allowing ventilation, blood perfusion and gas exchanges. Recent studies have demonstrated the possibility of in vitro and in vivo regeneration of lung tissue from autologous cells, and especially stem cells. This emerging research field is currently dominated by the use of decellularized lung matrices and autologous epithelial and endothelial cells. Implantation of such a recellularized matrix in animals has proved the feasibility of a functional bio-artificial lung. The first human transplantation of a bio-artificial lung should be possible within 10-20 years.

Elevated Circulating Stem Cells Level is Observed One Month After Implantation of Carmat Bioprosthetic Total Artificial Heart.

The Aeson® total artificial heart (A-TAH) has been developed as a total heart replacement for patients at risk of death from biventricular failure. We previously described endothelialization of the hybrid membrane inside A-TAH probably at the origin of acquired hemocompatibility. We aimed to quantify vasculogenic stem cells in peripheral blood of patients with long-term A-TAH implantation. Four male adult patients were included in this study. Peripheral blood mononuclear cells were collected before A-TAH implantation (T0) and after implantation at one month (T1), between two and five months (T2), and then between six and twelve months (T3). Supervised analysis of flow cytometry data confirmed the presence of the previously identified Lin-CD133+CD45- and Lin-CD34+ with different CD45 level intensities. Lin-CD133+CD45-, Lin-CD34+CD45- and Lin-CD34+CD45+ were not modulated after A-TAH implantation. However, we demonstrated a significant mobilization of Lin-CD34+CD45dim (p = 0.01) one month after A-TAH implantation regardless of the expression of CD133 or c-Kit. We then visualized data for the resulting clusters on a uniform manifold approximation and projection (UMAP) plot showing all single cells of the live Lin- and CD34+ events selected from down sampled files concatenated at T0 and T1. The three clusters upregulated at T1 are CD45dim clusters, confirming our results. In conclusion, using a flow cytometry approach, we demonstrated in A-TAH-transplanted patients a significant mobilization of Lin-CD34+CD45dim in peripheral blood one month after A-TAH implantation. Using a flow cytometry approach, we demonstrated in A-TAH transplanted patients a significant mobilization of Lin-CD34+CD45dim in peripheral blood one month after A-TAH implantation. This cell population could be at the origin of newly formed endothelial cells on top of hybrid membrane in Carmat bioprosthetic total artificial heart.

Multidimensional Proteomic Approach of Endothelial Progenitors Demonstrate Expression of KDR Restricted to CD19 Cells.

Endothelial progenitor cells (EPCs) are involved in vasculogenesis and cardiovascular diseases. However, the phenotype of circulating EPCs remains elusive but they are more often described as CD34+KDR+. The aim of the study was to extensively characterize circulating potential vasculogenic stem cell candidates in two populations of patients with cardiovascular disease by powerful multidimensional single cell complementary cytometric approaches (mass, imaging and flow). We identified cellular candidates in one patient before and after bioprosthetic total artificial heart implantation and results were confirmed in healthy peripheral and cord blood by mass cytometry. We also quantified cellular candidates in 10 patients with different COVID-19 severity. Both C-TAH implantation and COVID-19 at critical stage induce a redistribution of circulating CD34+ and CD19+ sub-populations in peripheral blood. After C-TAH implantation, circulating CD34+ progenitor cells expressed c-Kit stem marker while specific subsets CD34+CD133-/+CD45-/dimc-Kit+KDR- were mobilized. KDR was only expressed by CD19+ B-lymphocytes and CD14+ monocytes subpopulations in circulation. We confirmed by mass cytometry this KDR expression on CD19+ in healthy peripheral and cord blood, also with a VE-cadherin expression, confirming absence of endothelial lineage marker on CD34+ subtypes. In COVID-19, a significant mobilization of CD34+c-Kit+KDR- cells was observed between moderate and critical COVID-19 patients regardless CD133 or CD45 expression. In order to better evaluate EPC phenotype, we performed imaging flow cytometry measurements of immature CD34+KDR+ cells in cord blood and showed that, after elimination of non-circular events, those cells were all CD19+. During COVID-19, a significant mobilization of CD19+KDR+ per million of CD45+ cells was observed between moderate and critical COVID-19 patients regardless of CD34 expression. CD34+c-Kit+ cells are mobilized in both cardiovascular disease described here. KDR cells in peripheral blood are CD19 positive cells and are not classic vasculogenic stem and/or progenitor cells. A better evaluation of c-Kit and KDR expressing cells will lead to the redefinition of circulating endothelial progenitors.Graphical abstract Central illustration figure. Multidimensional proteomic approach of endothelial progenitors demonstrate expression of KDR restricted to CD19 cells. Endothelial progenitor cells (EPCs) are involved in cardiovascular diseases, however their phenotype remains elusive. We elucidated here EPCs phenotype by a deep characterization by multidimensional single cell complementary cytometric approaches after Bioprosthetic total artificial heart implantation and during COVID-19. We showed a redistribution of circulating CD34+ and CD19+ sub-populations in both situations. None of the immature cell population expresses KDR. Mobilized CD34+ expressed c-Kit. Imaging flow cytometry demonstrated that CD34+KDR+ cells, after elimination of non-circular events, are all CD19+. Our results suggest a new definition of circulating EPCs and emphasize involvement of CD19 cells in cardiovascular disease.