Human embryonic stem cells cultured on a Nipaam hydrogel artificial extracellular matrix. These hydrogels can be modified to alter the mechanical and chemical properties of the extracellular matrix, affecting cell behavior in vitro and tissue development in vivo. Courtesy of Kevin Healy.

Neuro-precursor cells isolated from the adult rat hippocampus and grown in vitro supported by FGF-2 are capable of generating neurons, astrocytes and oligodendrocytes. Stress and aging (through elevated levels of the stress hormone glucocorticoid)suppress the proliferation and the generation of new neurons in the hippocampus. Courtesy of Daniela Kaufer.

Morphological regulation of smooth muscle cell differentiation. Smooth muscle cells were grown on surfaces differently micropatterned with matrix proteins in order to manipulate cell morphology and cell-cell interactions. Courtesy of Song Li.

Endothelial cell structural networks. F-actin (red) assembles into long, straight stress fiber bundles, whereas microtubules (green) are highly curved, reflecting the different roles of these biopolymer systems in controlling cellular shape and mechanics. Cellular structural networks generate mechanical forces on the extracellular environment. Manipulation of these forces could be a mechanism for influencing a wide variety of cell behaviors, including the differentiation of neural stem cells. Courtesy of Sanjay Kumar.

Stem cells generate new neurons in several regions of the adult brain throughout our lives. This image shows newborn cells that continually divide (blue), and create mature cell types, including neurons (green) and astrocytes (red), in the hippocampus, a region of the brain associated with learning and memory. Courtesy of David Schaffer.

Satellite cells are muscle stem cells that repair and maintain skeletal muscle throughout adult life. With advancing age such regenerative potential declines and eventually fails. Studies of the effects of human embryonic stem cells (identified in this image by their expression of Oct-4, red) on de-novo myogenesis of mouse cells (shown in green) are directed towards understanding why stem cell regenerative capacity deteriorates with age. Courtesy of Irina Conboy.

Stem cells can be isolated from the hippocampus region of the adult brain and can be propagated indefinitely in cell culture. These cells are capable of specializing or differentiating into neurons, astrocytes (red), and oligodendrocytes (green), the three major cell types of the adult nervous system. Courtesy of David Schaffer.