The use of biomaterials to direct osteogenic differentiation of human mesenchymal stem cells (hMSCs) in
the absence of osteogenic supplements is thought to be part of the next generation of orthopedic
implants. We previously engineered surface-roughness gradients of average roughness (Ra) varying from
the sub-micron to the micrometer range (0.5–4.7 μm), and mean distance between peaks (RSm) gradually
varying from 214 μm to 33 μm. Here we have screened the ability of such surface-gradients of
polycaprolactone to influence the expression of alkaline phosphatase (ALP), collagen type 1 (COL1) and
mineralization by hMSCs cultured in dexamethasone (Dex)-deprived osteogenic induction medium
(OIM) and in basal growth medium (BGM). Ra 1.53 μm/RSm 79 μm in Dex-deprived OI medium,
and Ra 0.93 μm/RSm 135 μm in BGM consistently showed higher effectiveness at supporting the
expression of the osteogenic markers ALP, COL1 and mineralization, compared to the tissue culture polystyrene
(TCP) control in complete OIM. The superior effectiveness of specific surface-roughness revealed
that this strategy may be used as a compelling alternative to soluble osteogenic inducers in orthopedic
applications featuring the clinically relevant biodegradable polymer polycaprolactone.