Monday, July 12, 2010
Regenerating the Dental Pulp
Millions of teeth are saved each year by root canal therapy. Although current treatment modalities offer high levels of success for many conditions, an ideal form of therapy might consist of regenerative approaches in which diseased or necrotic pulp tissues are removed and replaced with healthy pulp tissue to revitalize teeth. Melanocortin peptides (α-MSH) possess anti-inflammatory properties in many acute and chronic inflammatory models. Our recent studies have shown that α-MSH covalently coupled to poly-l-glutamic acid (PGA-α-MSH) retains anti-inflammatory properties on rat monocytes. This study aimed to define the effects of PGA-α-MSH on dental pulp fibroblasts. Lipopolysaccharide (LPS)-stimulated fibroblasts incubated with PGA-α-MSH showed an early time-dependent inhibition of TNF-α, a late induction of IL-10, and no effect on IL-8 secretion. However, in the absence of LPS, PGA-α-MSH induced IL-8 secretion and proliferation of pulp fibroblasts, whereas free α-MSH inhibited this proliferation. Thus, PGA-α-MSH has potential effects in promoting human pulp fibroblast adhesion and cell proliferation. It can also reduce the inflammatory state of LPS-stimulated pulp fibroblasts observed in gram-negative bacterial infections. These effects suggest a novel use of PGA-α-MSH as an anti-inflammatory agent in the treatment of endodontic lesions. To better understand these results, we have also used the multilayered polyelectrolyte films as a reservoir for PGA-α-MSH by using not only PLL (poly-l-lysine) but also the Dendri Graft poly-l-lysines (DGLG4) to be able to adsorb more PGA-α-MSH. Our results indicated clearly that, by using PGA-α-MSH, we increase not only the viability of cells but also the proliferation. We have also analyzed at the nanoscale by atomic force microscopy these nanostructured architectures and shown an increase of thickness and roughness in the presence of PGA-α-MSH incorporated into the multilayered film (PLL-PGA-α-MSH)10 or (DGLG4-PGA-α-MSH)10 in accordance with the increase of the proliferation of the cells growing on the surface of these architectures. We report here the first use of nanostructured and functionalized multilayered films containing α-MSH as a new active biomaterial for endodontic regeneration.