The aim is to investigate the safety and tolerability of intravenous infusion of allogeneic umbilical cord mesenchymal stem cells in pediatric patients diagnosed with newly onset type 1 diabetes

This is an IIT study, where the first part is an open, dose escalating study consisting of 9 patients, 8-18 years of age. The second part is a randomized, double-blinded, placebo-controlled, IIT study in parallel design comparing allogeneic UCMSCs treatment to placebo in pediatric patients diagnosed with newly onset type 1 diabetes. Besides safety, preservation of endogenous insulin production (measured as C-peptide concentrations) together with metabolic control, diabetes treatment satisfaction and immunological profile will be assessed.

A total number of 24 patients will be enrolled in the study and followed for one year after UCMSCs/placebo treatment. Patients 8-18 years of age, both male and female, diagnosed for type 1 diabetes will be eligible. Providing informed consent and fulfillment of inclusion criteria and no exclusion criteria, they will within 6 months of diagnosis be randomized.

Inclusion Criteria:

1. Meets the diagnostic criteria for diabetes according to the World Health Organization (WHO) guidelines from 1999.
2. Presence of at least one pancreatic autoantibody, or idiopathic type 1 diabetes mellitus (T1DM) with negative autoantibody testing.
3. Ages 8 to 18 years, regardless of gender.
4. Newly diagnosed T1DM within the past 6 months.
5. Fasting C-peptide ≥0.1 nmol/L and postprandial 2-hour C-peptide >0.2 nmol/L.
6. Voluntary acceptance of stem cell transplantation therapy by the individual, their family members, or legal guardians, and signing of an informed consent form.

Exclusion Criteria:

1. Diabetic ketoacidosis is not under control.
2. Severe allergic constitution.
3. BMI <14 or >35.
4. History of other autoimmune diseases, hematologic disorders.
5. HIV positive, carrier of viral hepatitis, active phase of viral hepatitis, or other uncontrolled infectious diseases.
6. History of acute pancreatitis, pulmonary embolism, or other thrombotic diseases, as well as severe diseases of the heart, liver, kidneys, respiratory system, nervous system, etc.
7. Suffering from gestational diabetes, monogenic diabetes, diabetes caused by pancreatic injury, or other secondary diabetes (such as Cushing's syndrome, thyroid dysfunction, or acromegaly-induced diabetes);
8. Pregnancy or planning pregnancy within 3 months before or after treatment, as well as breastfeeding women.
9. Mental illness, alcohol or drug abuse, inability to comply with treatment.
10. Known or suspected tumors.
11. According to the investigator's judgment, there are other clinical conditions that may endanger the safety of the subjects.