A fuel cell stack with a bipolar plate assembly and a method of assembling a fuel cell stack such that reactant or coolant leakage is reduced. Bipolar plates within the system include reactant channels and coolant channels that are fluidly coupled to inlet and outlet flowpaths, all of which are formed within a coolant-engaging or reactant-engaging surface of the plate. One or more thin or low aspect-ratio microseals are also formed on a metal bead that is integrally-formed on a surface of the plate and is used to help reduce leakage by maintaining fluid isolation of the reactants and coolant as they flow through their respective channels and flowpaths that are defined between adjacently-placed plates. By delaying the activation of the adhesive bond formed between the microseal and an adjacent surface within the fuel cell until after the aligned cell assemblies have been compressively supported in a stack housing, the ability of the microseal and its adjacent surface to avoid reactant or coolant leakage is enhanced.