Methods to elevate progenitor and stem cell counts in animal subjects using compounds which bind to the chemokine receptor CXCR4 are disclosed. Preferred embodiments of such compounds are of the formula Z-linker-Z' (1) or pharmaceutically acceptable salt thereof wherein Z is of the formula ##STR00001## wherein A comprises a monocyclic or bicyclic fused ring system containing at least one N and B is H or an organic moiety of 1 20 atoms, Z' is of the formula --Ar(Y).sub.j; wherein Ar is an aromatic or heteroaromatic moiety, and each Y is independently a non-interfering substituent and j is 0 3; and "linker" represents a bond, alkylene (1 6C) or may comprise aryl, fused aryl, oxygen atoms contained in an alkylene chain, or may contain keto groups or nitrogen or sulfur atoms.