Biomimetic Habitats for Cells: Ordered Matrix Deposition and Differentiation in Gingival Fibroblasts Cultured on Hydroxyapatite Coated with a Collagen Analogue

In tissues, cells attach and migrate on collagen. Interaction with collagen modulates cell proliferation and differentiation. We propose that similar environments may be constructed by immobilizing collagen-derived cell-binding peptides in a three-dimensional (3-D) template. We identified a cell binding domain of type I collagen and showed that a 15-residue synthetic analogue (P-15) binds cells with high affinity. In the present study, we compared the behavior of human gingival fibroblasts (HGF) in culture on hydroxyapatite (HA) and on HA-P-15. HGF cultured on HA formed sparse monolayers with little order and deposited a scant matrix. HGF on HA-P-15 formed highly oriented 3-D colonies and deposited copious amounts of fibrous and membranous matrix. Northern analysis showed increased expression of osteogenic markers type I collagen, alkaline phosphatase, osteonectin and transforming growth factor ß-1 on HA-P-15. Alizarin red stained the matrix of HGF cultures on HA-P-15 suggesting neo-mineralization. Gingival fibroblasts are a source of reparative cells in periodontal tissue repair. Our studies support this concept and suggest that HA-P-15 matrices may be effective as endosseous grafts. When seeded with appropriate cells HA-P-15 matrices may serve as tissue engineered bone substitutes