The main aim of the study is to determine whether intramuscular injection of umbilical cord mesenchymal stem cells can improve the ventricular function of children with idiopathic dilated cardiomyopathy(IDCM); Secondary end-points will be: 1)To explore the possible mechanism of the improvement of ventricular function in children with IDCM and 2) to evaluate the safety of intramuscular injection of umbilical cord mesenchymal stem cell.

Children with Idiopathic dilated cardiomyopathy class II to III NYHA with ejection fraction over 20% were selected for phase II clinical trial, umbilical cord mesenchymal stem cells were injected into limb muscle and followed for 6 months.

Inclusion Criteria:

• Children of both genders with established clinical and echocardiographic diagnosis of dilated cardiomyopathy whose parents accept to participate in the trail.
• They should have symptoms and /or signs of heart failure, despite optimized medical treatment.
• Ejection fraction of left ventricular should be less than 50%, but more than 20%.

Exclusion Criteria:

• associate coronary artery disease.
• any history or suspicion of a toxic , pharmacologic or deposit etiology.
• associated malignant or pre -malignant systemic disease.
• associated hematologic disorder.
• a history of sustained ventricular tachycardia or fibrillation.
• a history of syncope during the previous year, or with an active infectious disease or positive tests to viral disease.