Inclusion Criteria:
1. Aged between 18 to 80 years
2. Signed written informed consent
3. French Social Security affiliation;
4. Dilated cardiomyopathy defined by a dilated LV with a reduced EF ≤40% on echocardiography and/or CMR imaging, unexplained by pressure or volume overload (severe arterial hypertension or significant valve disease), coronary artery disease (as assessed by coronary angiography) or a systemic disease; in case of chemotherapy-induced cardiomyopathy, patients should have a period of at least two years of clinical cancer-free state\* and a low estimated likelihood of recurrence (≤30% at 5 years), as determined by an oncologist, based on tumor type, response to therapy, and negative metastatic work-up at the time of diagnosis (\*exceptions to this are carcinoma in situ or fully resected basal and squamous cell cancer of the skin);
5. NYHA Class III in spite of optimal heart failure maximally tolerated guideline-directed medical therapy, including cardiac resynchronization if needed, without other treatment options;
6. Plasma level of B-type natriuretic peptide (BNP) \> 150 pg/mL or, N-terminal pro-BNP (NT-proBNP) ≥ 400 pg/mL;
7. For child-bearing aged women, efficient contraception such as combined (estrogen and progestogen containing) hormonal contraception or progestogen-only hormonal contraception associated with inhibition of ovulation and for men efficient contraception such as condom, during treatment and until the end of the relevant systemic exposure, i.e. until 3 months after the end of treatment.
Exclusion Criteria:
1. Implantation of a cardiac resynchronisation therapy device or an ICD unit during the preceding 3 months;
2. End-stage heart failure with reduced EF (HFrEF) defined as patients with American College of Cardiology Foundation/American Heart Association (ACCF/AHA) stage D (candidates for specialized interventions, including heart transplantation and mechanical assistance) or terminal HF (advanced HF with poor response to all forms of treatment, frequent hospitalizations and life expectancy \< 12 months)
3. Patients treated with inotropic agents during the 1 month period prior to inclusion;
4. Acute heart failure (regardless of the cause);
5. Heart failure caused by cardiac valve disease, untreated hypertension or documented coronary artery disease with lesions which could explain the cardiomyopathy;
6. Cardiomyopathy due to a reversible cause e.g. endocrine disease, alcohol or drug abuse, myocarditis, Tako-Tsubo, or arrhythmias;
7. Cardiomyopathy due a syndromic/systemic disease (e.g. Duchenne's muscular dystrophy, immune/inflammatory/infiltrative disorders \[amyloidosis, hemochromatosis\]);
8. If post-chemotherapy cardiomyopathy: a history of radiation therapy AND evidence of constrictive physiology; a baseline computerized tomography scan or CMR showing new tumor or suspicious lymphadenopathy raising concern of malignancy; a trastuzumab treatment within the last 3 months;
9. Previous cardiac surgery;
10. Recent stroke (within the last 3 months);
11. Documented presence of a known LV thrombus, aortic dissection, or aortic aneurysm;
12. Uncontrolled ventricular tachycardia defined by sustained ventricular tachycardia, including electrical storm and incessant ventricular tachycardia with no response to antiarrhythmic medication; Internal Cardioverter Defibrillator firing in the 30 days prior to the first infusion;
13. History of drug-induced allergic reactions or allergy of any type having required treatment;
14. Contraindication to corticosteroids or anti-histaminic agents;
15. Contraindication to gadoterate meglumine if it will be used with CMR;
16. Hematological disease: anaemia (haematocrit \< 25%), leukopenia (leucocytes \< 2,500/μL) or thrombocytopenia (thrombocytes \< 100,000/μL); myeloproliferative disorders, myelodysplastic syndrome, acute or chronic leukaemia, and plasma cell dyscrasias (multiple myeloma);
17. Coagulopathy not due to a reversible cause;
18. Diminished functional capacity for other reasons such as: Chronic Obstructive Pulmonary Disease (COPD) with Forced Expiratory Volume (FEV) \<1 L/min, moderate to severe claudication or morbid obesity;
19. Diabetes with poorly controlled blood glucose levels and/or evidence of proliferative retinopathy;
20. Dialysis-dependent renal insufficiency;
21. Autoimmune disorders or current immunosuppressive therapy;
22. History of organ transplant or cell-based treatment;
23. Serum positivity for HIV, hepatitis BsAg, or viremic hepatitis C;
24. Female patient who is pregnant, nursing, or of child-bearing potential and not using effective birth control;
25. Active infection;
26. Known allergy to aminoglycosides;
27. Patient under legal protection (guardianship);
28. Participation in another interventional trial;
29. Life expectancy less than one year.
30. Contraindication to 18FDG-PETscan
