NDNF and Alzheimer disease: Among these 569 factors, 17 were significantly overrepresented in the conditioned medium derived from DFX-preconditioned AD-MSCs, including potent angiogenic factors such as VEGF-α and NDNF, which could explain the superiority of this conditioned medium to potentiate the angiogenesis process compared to conditioned medium derived from non-preconditioned AD-MSCs.