Disclosed herein are extracts of blue green algae, such as Aphanizomenon flos aquae, that are enriched for a selectin ligand, such as an L-selectin ligand. Selectin ligands isolated from blue-green algae cells are disclosed herein. Methods are described for isolating these selectin ligands. The purified selectin ligands are of use in inducing stem cell mobilization in a subject. Thus, methods for inducing stem cell isolation that include administering a therapeutically effective amount of the extract enriched form the selectin ligand, or an isolated selectin ligand, are disclosed herein.