Tissue Engineering of a Periodontal Ligament-Alveolar Bone Graft Construct

Purpose: This paper reports on a 2-phase study of a novel membrane-scaffold graft construct, its ability to support periodontal ligament fibroblast (PDLF) and alveolar osteoblast (AO) growth in vitro, and its use for tissue engineering a PDL-AO interface in vivo. Materials and Methods: Human PDLFs were seeded onto perforated poly(e-caprolactone) membranes (n = 30) at 78,000 cells/cm2; human AOs were seeded on poly(e-caprolactone) scaffolds (n = 30) with fibrin glue at 625,000 cells/cm3. Cell attachment, morphology, viability, and metabolic activity were monitored for 3 weeks in vitro. Subsequently, cell-seeded membrane-scaffold constructs (experimental group, n = 9) and nonseeded constructs (control group, n = 4) assembled with fibrin glue were implanted subcutaneously into 7 athymic mice for 4 weeks. Results: PDLFs formed confluent layers on membranes, whereas AOs produced mineralized matrices within scaffolds upon osteoinduction in vitro. Well-vascularized tissue formation was observed after implantation. Integration at the membrane-scaffold interface was enhanced in the experimental group. Type I collagen, type III collagen, fibronectin, and vitronectin were found adjacent to membranes and within constructs. Bone sialoprotein expression and bone formation were undetectable. Discussion: Membrane perforation and scaffold porosity facilitated tissue integration and vascularization at the construct-recipient site. However, the interaction between PDLF and AO could have interfered with osteogenesis at the interface of soft and mineralizing tissues. Conclusions: Both matrices supported PDLF and AO attachment and proliferation in vitro. The membrane-scaffold construct facilitated tissue growth and vascularization while providing strength and form in vivo. Keywords: alveolar osteoblasts, graft construct, human periodontal ligament fibroblasts, poly (e-caprolactone)