HTRA1 and age-related macular degeneration: Furthermore, Saini et al. [13] revealed the function of nicotinamide in AMD using the iPSC model; they noted that ICAM1, which has been linked to the development of the wet form of AMD, was strongly upregulated in human AMD ARMS2/HTRA1 iPSC-RPE and was markedly inhibited by nicotinamide [13].