Collagen-coated poly(L-lactide-co-ε-caprolactone) film: A promising scaffold for cultured periosteal sheets

Background: We previously demonstrated that human periosteal sheets prepared on culture dishes function as an osteogenic "graft material" applicable to periodontal regenerative therapy. However, a lower level of initial adhesion of the excised periosteum tissue segments to culture dishes was a critical point that compromised the successful preparation of functional periosteal sheets. To improve on this weakness, we developed a transparent, biodegradable poly(L-lactide-co-ε-caprolactone) (LCL) film and tested its function as a scaffold and carrier of periosteal sheets. Methods: Human periosteum tissue segments excised from alveolar bone of healthy donors were cultured on type I atelocollagen-coated LCL films. Initial adhesion was examined by simple agitation. Cell outgrowth and in vitro mineralization were cytohistochemically examined. Osteogenic activity was histochemically examined in an animal implantation model using nude mice. Results: Surface collagen-coating modified the hydrophobic nature of LCL and substantially improved the initial adhesion. Compared to cultures in plastic dishes, the growth rate was delayed in non-coated films, but not in collagen-coated films. In the trimming process for animal implantation, periosteal sheets were frequently detached from non-coated films, but not from collagen-coated films. Regardless of collagen-coating, LCL films did not cause any significant infiltration of inflammatory cells, or negatively impact mineralized tissue formation. Conclusions: Collagen-coating improved the initial adhesion of periosteum segments, which facilitated cell outgrowth and also handling efficiency on implantation. Therefore, we believe that once evaluated in human studies, our collagen-coated LCL film will contribute to improving the periodontal regenerative methodology with the application of cultured autologous periosteal sheets.