The present invention discloses a closed-loop hydraulic circuit for in vitro simulation of blood flow and for testing the effect of such simulated flow on a biological sample, comprising:- a tank for storing a flowing liquid；- a constant flow pump for pumping the liquid out of the tank for imposing, in use, an average constant flow in the hydraulic circuit；- a pulsating pump for superimposing to said average constant flow a variable flow having a zero average flow rate；- a test section for receiving a biological sample to be tested under flow conditions imposed by the said means；- means for regulating the pressure downstream of the test section；- pressure and flow sensors for sensing pressure and flow conditions in the test section；- means for measuring and collecting biological data in the test section；- a control unit comprising regulation means for controlling the constant flow pump and the pulsating pump.
