Development of Ligament-Anchored Dental Implants Using Cell Sheets on Sulfonated PEEK Surfaces Coated With Boron-Doped Nano-Hydroxyapatite

This study aimed to biologically modify polyetheretherketone (PEEK) using cell sheets after chemical modification, with the goal of enhancing its bioactivity and improving its integration with dental tissue. To achieve this, sulfonated PEEK (SPEEK) and/or boron-doped nanohydroxyapatite (B-nHAp)-coated SPEEK (SPEEK-B-nHAp) materials were combined with periodontal ligament (PDL) or PDL-co-human umbilical vein endothelial (HUVEC) cell sheets. PDL and PDL-co-HUVEC cell sheets were obtained from 12-well plates over a 4-day period using L-ascorbic acid induction (100 μg/mL) and a concentrated cell density of 1.0 × 10⁵ cells/cm². Both PDL and co-culture cell sheets adhered well to and proliferated on the surfaces of SPEEK and SPEEK-B-nHAp. However, the co-culture cell sheet groups showed faster growth compared to the PDL cell sheet groups on both SPEEK and SPEEK-B-nHAp materials at each time point. Western blot and RT-PCR analyses revealed a significant increase in early- and mid-term osteogenic markers in PDL cell sheets on both SPEEK and SPEEK-B-nHAp surfaces. Additionally, late-stage osteogenic and angiogenic markers were enhanced in the co-culture cell sheets on both SPEEK and SPEEK-B-nHAp samples. This study concluded that PDL-co-HUVEC cell sheets covering SPEEK-B-nHAp surfaces can effectively support bone-implant integration and represent a promising modification approach for PEEK dental implants.