Post microtextures accelerate cell proliferation and osteogenesis

The influence of surface microtexture on osteogenesis was investigated in vitro by examining the proliferation and differentiation characteristics of a class of adult stem cells and their progeny, collectively known as connective tissue progenitor cells (CTPs). Human bone marrow-derived CTPs were cultured for up to 60days on smooth polydimethylsiloxane (PDMS) surfaces and on PDMS with post microtextures that were 10μm in diameter and 6μm in height, with 10μm separation. DNA quantification revealed that the numbers of CTPs initially attached to both substrates were similar. However, cells on microtextured PDMS transitioned from lag phase after 4days of culture, in contrast to 6days for cells on smooth surfaces. By day 9 cells on the smooth surfaces exhibited arbitrary flattened shapes and migrated without any preferred orientation. In contrast, cells on the microtextured PDMS grew along the array of posts in an orthogonal manner. By days 30 and 60 cells grew and covered all surfaces with extracellular matrix. Western blot analysis revealed that the expression of integrin α5 was greater on the microtextured PDMS compared with smooth surfaces. Real time reverse transcription-polymerase chain reaction revealed that gene expression of alkaline phosphatase had decreased by days 30 and 60, compared with that on day 9, for both substrates. Gene expression of collagen I and osteocalcin was consistently greater on post microtextures relative to smooth surfaces at all time points.