Methods to promote Notch signaling at the biomaterial interface and evaluation in a rafted organ culture model

The Notch signaling pathway is a promising target for controlling cell fate choices at the biomaterial-tissue interface. Building on our previous work in developing Notch-signaling biomaterials, we evaluated various immobilization schemes for Notch ligands, and their effect on human foreskin keratinocytes. A peptide sequence derived from the Jagged-1 DSL-region and immobilized to poly(2-hydroxyethyl methacrylate) (polyHEMA) showed no bioactivity in relation to the Notch-CSL pathway. The full-length Jagged-1 protein immobilized directly to the polyHEMA surface showed activity in signaling the Notch-CSL pathway. However, an indirect affinity immobilization approach yielded a stronger signal. Human keratinocytes plated on bound Jagged-1 showed upregulated involucrin, keratin 10, and loricrin protein expression, with this expression being cell density-dependent. Utilizing a human foreskin rafted organ culture model as a bridge between in vitro and in vivo studies, Jagged-l-modified or control polyHEMA rods were implanted in human foreskin and cultured at the air-medium interface. Keratinocyte proliferation was suppressed and intermediate-stage differentiation promoted in Jagged-1-modified rods compared with control rods. Thus, Notch-signaling biomaterials provide a robust approach to control keratinocyte differentiation and may find application to other progenitor and stem cells. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 91A: 436-446, 2009