The objective of this study is to evaluate the safety, tolerance, pharmacokinetics and the potential immunological reaction of single intravenous recombinant human thymosin β4（NL005）or placebo 0.5, 2.0,5.0μg/kg in Chinese healthy volunteers.30 volunteers will be randomly assigned to one of three groups to receive either NL005 or placebo for 10 consecutive days.

This study was a randomized, double-blind, placebo-controlled study to evaluate the safety and tolerability pharmacokinetics and potential immune responses of multiple NL005 intravenous administration.

Three groups of 30 subjects will receive an NL005 or placebo dose of 0.5μg/kg 2.0 μg/kg and 5.0 μg/kg for 10 consecutive days at a ratio of 4:1.

While observing the safety of the subjects in each dose group, about 5mL of venous blood was collected for the ADA study in healthy subjects 14 days and 28 days after the first administration of the drug.

Inclusion Criteria:

1. Chinese healthy volunteers（male or female）.
2. Between 18 and 50 years of age.
3. Female subjects should weigh no less than 45 kg and male subjects should weigh no less than 50 kg.BMI between 19 and 28 kg/m2.
4. Good health condition, no history of unintentional, liver, kidney, digestive tract, immune system, nervous system, mental and metabolic abnormality, no family history of tumor.
5. Ability to communicate normally with medical staff, understand research requirements and comply with hospital regulations.
6. Voluntarily sign informed consent.

Exclusion Criteria:

1. Physical examination vital signs electrocardiogram and laboratory examination are not done or any result is judged to be clinically significant abnormal (judged by clinician).
2. ADA tests positive.
3. Smoking more than 5 cigarettes a day for the previous 3 months, or no guarantee to stop smoking during the trial.
4. Previous history of substance abuse or drug screening test positive.
5. Alcohol intake averaged more than 2 units per day (1 unit = 360mL beer,150mL wine or 45mL 40% alcohol liquor) or alcohol test positive in the first 3 months of inclusion.
6. Participated in another trial or used this drug within 3 months before inclusion.
7. Any other drug was used within two weeks before the trial.
8. There is a significant clinical history of allergy, especially for drugs, protein preparations and biological products, especially for rh-tβ4 or any of its ingredients.
9. Blood donation or blood loss was equal to or greater than 400 mL within three months prior to the trial.
10. Female subjects who are pregnant or breast-feeding, or who are likely to become pregnant without using an acceptable method of contraception, or who are positive for a pregnancy test, and male subjects who are not using effective contraception or whose partner has a family planning plan within six months of the end of the trial.
11. Unable to tolerate venous blood collection.
12. There is no guarantee that smoking and taking grapefruit juice or any alcoholic and xanthine food and beverage (including chocolate, tea, coffee, cola, etc.) from 48 hours before administration to the last blood sample collection.
13. The investigator judges that the subject is unable to complete the study or otherwise considers that the subject's participation in the study may cause other injury.