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.