DAB immunohistochemistry of adult human hippocampus sections and immunocytochemistry of the isolated cells showing positive staining for prolyl-4-hyroxylase (P4H; A–D), Vimentin (E–H) and alpha-smooth muscle actin (Alpha-SMA; I-L). Higher magnification images show P4H to be localized in the pyramidal cells of the CA1 region (A, B; red arrow) and in the blood vessels throughout the section (A, C; white arrow). Vimentin was largely localized to the astrocytes in the white matter (including stratum radiatum; E-F; red arrow), and again, the blood vessels (E-G; white arrow). Alpha-SMA staining was only visible in the blood vessels (I-K; all arrows). Scale: (B-C, F-G, J-K) = 60 µm, (D, H, L) = 100 µm. (M) Comparative analysis of gene expression using q-RT-PCR for FbCs and fibroblast cells isolated and grown from the adult human brain and lung respectively. The level of expression was measured using a standard curve and normalized to a house-keeping gene, GAPDH. From the graph, it is evident that our brain-derived FbCs have a fibroblast-like gene expression profile that appears to be more vasculature cell-like than mescenchymal stem cell (MSC)-like.