  This report focuses on the effect of the surface topography of the substrate
on the behavior of human mesenchymal stem cells from bone marrow (MSCs) before
and after co-differentiation into adipocytes and osteoblasts. Picosecond pulsed
laser ablation technology was applied to generate different microstructures
(microgrooves and microcavities) on poly (L-lactide) (PLLA), where orientation,
cell shape and MSCs co-differentiation were investigated. On flat PLLA, the
undifferentiated MSCs showed rounded or elongated shapes, the latter being
randomly oriented. On PLLA microgrooves however, MSCs adapted their shape to
the groove size and direction and occasionally anchored to groove edges. It was
found that adipocytes, contrary to osteoblasts, are highly sensitive to
topological cues. Adipocytes responded to changes in substrate height and
depth, by adapting the intracellular distribution of their lipid vacuoles to
these physical constraints. In addition, the modification of PLLA by laser
ablation enhanced the adherence of differentiated cells to the substrate. These
findings show that picosecond pulsed laser micromachining can be applied to
directly manufacture 3D microstructures that guide cell proliferation, control
adipocyte morphology and improve the adhesion of bone and fat tissue.
