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 0.05, 0.25, 0.5, 2, 5, 12.5, 25μg/kg in Chinese healthy volunteers. 54 volunteers will be randomized to receive NL005 or placebo for 7 cohorts,administered iv by iv push on Day 1.

This study is a randomized,double-blind,placebo-controlled, investigation to evaluate the safety, tolerability, pharmacokinetics and the potential immunological reaction of single of NL005 administered intravenously to healthy volunteers.

In Phase 1A, Seven (7) cohorts of subjects (first two cohorts 2 subjects respectively, 10 subjects per cohort for next 5 cohorts) will administered one dose of NL005 or placebo in a 4:1 ratio. Dosing start at 0.05μg/kg and advance to 0.25, 0.5, 2, 5, 12.5, 25μg/kg.

NL005 or placebo administered as a single dose on Day 1. Safety parameters recorded on Study Days 1, 2, 5, 14, and 28. Evaluation of adverse events performed throughout the study. Pharmacokinetic samples obtained on Study Day 1. Blood samples collected for serum antibody determinations at Screening , Days 14 and 28.

Inclusion Criteria:

1. Chinese healthy volunteers（male or female）.
2. Between 18 and 50 years of age.
3. 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. Medical history , physical examination, laboratory examinations are normal or not clinically significant abnormalities, and the investigator judges those who are qualified.
6. Voluntarily sign informed consent.

Exclusion Criteria:

1. Physical examination, vital signs, ECG or laboratory examinations are abnormal (clinically significant ).
2. Active hepatitis b or c patients, carriers of hepatitis b virus.
3. HIV antibody test positive or syphilis spiral antibody test positive.
4. ADA tests positive.
5. Smoke more than 5 cigarettes a day, had a suspected or proven history of substance abuse, and consumed an average of more than 2 units of alcohol per day for 3 months (1 unit =12 ounces or 360mL beer, 5 ounces or 150mL liquor, 1.5 ounces or 45mL distilled liquor) or had a positive alcohol test.
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. Women who are pregnant or breast-feeding, or who are likely to become pregnant and do not use an acceptable method of contraception, or who have a positive pregnancy test and who do not use effective contraception or whose partner plans to give birth within six months.
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.