Thermosensitive hydrogels functionalized with pH sensitive COOH groups for bone cell harvesting

Abstract

Vinyl-caprolactam based thermosensitive hydrogel films, capable of detach cell monolayers in a non-aggressive manner upon decrease of temperature, were functionalized with carboxylic groups at different molar percentages ranging from 1 up to 12%. This functionalization was carried out by a bottom-up approach incorporating methacrylic acid (MAA) to the photo-polymerization reaction. Incorporation of MAA led to hydrogels with dual sensitivity to temperature and pH. While the functionalization has shown to have a small influence on the transition temperature, the carboxylic load plays a key role on the water uptake at these two conditions, i.e. at temperatures and pHs both above or both below transition values. A C2C12-GFP mouse muscle premyoblastic cell line was used to comparatively study cell cytocompatibility and cell detachment capability. Although all hydrogels have shown to be cytocompatible, the carboxylic group has shown, for MAA molar contents higher than 5% and in a composition-dependent manner, a negative influence on the early cell adhesion, as well as on the comparative number of detached cells. Finally, MC3T3-E1 mouse preosteoblastic cell line was studied to both analyze cell harvesting and bone differentiation processes by studying collagen secretion and calcium deposits formation. Up-regulation of collagen secretion and matrix mineralization was observed for the samples with the highest MAA content, showing that MAA functionalization successfully improved bone matrix synthesis.