We recently developed a
nitrogen-rich plasma-polymerized
biomaterial, designated "PPE:N" (N-doped plasma-polymerized
ethylene) that is capable of suppressing cellular
hypertrophy while promoting
type I collagen and
aggrecan expression in mesenchymal stem cells from
osteoarthritis patients. We then hypothesized that these surfaces would form an ideal substrate on which the nucleus pulposus (NP) phenotype would be maintained. Recent evidence using microarrays showed that in young rats, the relative
mRNA levels of
glypican-3 (GPC3) and
pleiotrophin binding factor (PTN) were significantly higher in nucleus pulposus (NP) compared to annulus fibrosus (AF) and articular cartilage. Furthermore,
vimentin (VIM)
mRNA levels were higher in NP versus articular cartilage. In contrast, the levels of expression of
cartilage oligomeric matrix protein (COMP) and
matrix gla protein precursor (MGP) were lower in NP compared to articular cartilage. The objective of this study was to compare the expression profiles of these genes in NP cells from fetal bovine lumbar discs when cultured on either commercial
polystyrene (PS) tissue culture dishes or on PPE:N with time. We found that the expression of these genes varies with the concentration of N ([N]). More specifically, the expression of several genes of NP was sensitive to [N], with a decrease of GPC3, VIM, PTN, and MGP in function of decreasing [N]. The expression of
aggrecan,
collagen type I, and
collagen type II was also studied: no significant differences were observed in the cells on different surfaces with different culture time. The results support the concept that PPE:N may be a suitable scaffold for the culture of NP cells. Further studies are however necessary to better understand their effects on cellular phenotypes.