The characteristic features of nanomaterials provide rich opportunities for a broad range of applications due to their different physicochemical properties. Nanocolloidal silver and graphenic carbon materials differ in most physicochemical characteristics, except for their nanodimensions. Since there is a growing demand for stem cell therapies for coronary disorders, examining cardiac progenitor cells (CPC) in terms of their response to nanostructure treatment seems to be a reasonable approach. Morphological studies and viability assessments were performed with CPC in vitro, treated with small concentrations of silver nanoparticles (AgNP), hierarchical nanoporous graphenic carbon (HNC) and their mixtures. A viability test confirmed the morphological assessment of CPC treated with AgNP and HNC; moreover, the action of both nanomaterials was time-dependent and dose-dependent. For AgNP, between the two of the applied concentrations lies a border between their potential beneficial effect and toxicity. For HNC, at a lower concentration, strong stimulation of cell viability was noted, whereas a higher dosage activated their differentiation. It is necessary to perform further research examining the mechanisms of the action of AgNP and especially of unexplored HNC, and their mixtures, on CPC and other cells.