  We show that electron tunneling from edge states in two-dimensional
topological insulator into a parallel electron waveguide leads to the
appearance of spin-polarized current in the waveguide. The spin polarization
$P$ can be very close to unity and the electron current passing through the
tunnel contact splits in the waveguide into two branches flowing from the
contact. The polarization essentially depends on the electron scattering by the
contact and the electron-electron interaction in the one-dimensional edge
states. The electron-electron interaction is treated within the Luttinger
liquid model. The main effect of the interaction stems from the renormalization
of the electron velocity, due to which the polarization increases with the
interaction strength. Electron scattering by the contact leads to a decrease in
$P$. A specific effect occurs when the bottom of the subbands in the waveguide
crosses the Dirac point of the spectrum of edge states when changing the
voltage or chemical potential. This leads to changing the direction of the spin
current.
