ST. LOUIS, Mo., Aug. 13 /PRNewswire-FirstCall/ -- Sigma-Aldrich(R) today announced an agreement with Glycosan BioSystems for the sale of HyStem(TM), a fully customizable synthetic extracellular matrix (ECM) for stem cell research. HyStem offers researchers flexibility to tailor microenvironments for their cultured cells that mimic natural in vivo conditions, optimizing stem cell proliferation and differentiation. HyStem was developed by Glycosan BioSystems and will be sold by Sigma-Aldrich under a non-exclusive distribution agreement (http://www.sigma.com/hystem).