Capability of Tissue Stem Cells to Organize into Salivary Rudiments
Figure 4
Organization of human SGP cells into a branching organ-like structure. A total of 3,000 cultured human SGP cells were suspended in 100 μl of differentiation medium and seeded over a thick gel layer in each well of a 96-well plate. The seeded cells were cultured on 2 types of gels: Matrigel and PuraMatrix Peptide Hydrogel (BD Biosciences). Culture media were changed at 3-day intervals in both cell cultures. Matrigel contains both ECM proteins and several growth factors, whereas PuraMatrix peptide hydrogel consists of standard amino acids (1% w/v) and 99% water. The differentiation medium consists of Williams’ E medium supplemented with ITS-X (GIBCO Invitrogen) and 20 ng/mL of recombinant human EGF (Sigma). (a) shows seeded cells on each gel at day 0. (b) After 7 days, human SGP cells cultured on PuraMatrix failed to form a branching structure and exhibited only loose cell-to-cell aggregation without a round end-bud and stalk. (c), (d), (e) In comparison, human SGP cells cultured on Matrigel organized into a branching structure with stalks and round end buds. (c) shows human SGP cells cultured on Matrigel for 7 days, and (d) shows the culture for 14 days. (e) is a magnified image within the frame of (d). The arrowhead indicates the stalk portion without the lumen in (e). Arrows indicate cleft-like portions in the round end buds in panels (c) and (e). Original magnifications, (d), (a, b, c, e). Scale bars =100 μm.
