This study is designated to:

1. investigate the tolerance and safety of treatment of Human placental mesenchymal stem cells gel on Human diabetic foot ulcer.
2. learn the primary effectiveness of Human placental mesenchymal stem cells gel on Human diabetic food ulcer.
3. study the pharmacokinetics of Human placental mesenchymal stem cells gel on Human diabetic food ulcer.

Inclusion Criteria:

• Age ≥ 18 and Age ≤ 75
• Type 1 or type 2 diabetes mellitus, glycosylated hemoglobin ≤ 9.0%
• Diagnosed as condition of diabetic foot ulcer, Wagner grade at 1 or 2 after clinical treatment
• Full understand the informed consent form, and signed it voluntarily

Exclusion Criteria:

• Pregnant or breast-feed women or plan to pregnant or fail to take an efficient contraception
• Be allergic to any component of the drug or showed allergic constitution
• Showed a sign of systemic infection, or with complication of ethmyphitis, or osteomyelitis indicated by MRI
• Have malignancy in the ulcer pathology test, or have a history of malignant tumor
• Unable to clean the wounds due to the formation of tract between the ulcer and other condition
• Infected with hepatitis B virus (HBV), hepatitis virus C (HCV), human immunodeficiency virus (HIV), or treponema pallidum
• Alanine transaminase (ALT) or aspartate transaminase (AST) exceeds 2.5 times of the normal value, or Cr>200 μmol/L
• Have a history of apoplexy, unstable angina pectoris, myocardial infarct
• Have a psychiatric history, drug abuse or alcohol abuse history
• Had participated in any other clinical trials in the past 3 months
• Any other circumstances judged by the researchers disqualify the patient to participate in the trial