Phosphorylated Pullulan Bioadhesive for Hard-Tissue Reconstruction
Yoshida, Y. Takahata, T. Nakamura, M. Irie, M. Tanaka, M. Ozaki, T. Suzuki, K. Van Meerbeek, Bart #
IADR location:Barcelona date:14-17 July 2010
A bioadhesive that can be bonded to hard tissue such as bone and tooth, is highly needed for hard-tissue repair in orthopaedic medicine and dentistry. Objectives: The purpose of this study is to develop a novel hard-tissue biodegradable adhesive on basis of phosphorylated pullulan (PP). Methods: The pharmacopoeial PP was chemically functionalized with dihydrogen phosphate groups to chemically bridge the biomaterial with the hard tissue via ionic binding of the phosphate functional groups to Ca of apatite. Shear bond strengths of the experimental bioadhesive to hydroxyapatite and titanium were compared with those of commercial PMMA (Surgical Simplex P, Howmedica, Ireland) and calcium-phosphate (BIOPEX-R, Hoya, Japan) bone cements. For histological examination, mixtures of PP sodium salt and calcium phosphate were injected in a hole prepared with a 23-gauge needle into the femur of eight-week-old wild type C57/bl6 male mice. The latter were sacrificed at 2, 5 and 8 weeks, and the respective femurs harvested and lab-processed for light microscopy. Results: The novel cement (14.7±1.9 and 18.3±5.3 MPa) bonded significantly (one-way ANOVA and Scheffe Multiple Comparisons test, p<0.05) better to hydroxyapatite and titanium than the commercial PMMA (11.4±1.7 and 10.1±3.4 MPa) and calcium-phosphate (1.3±1.3 and 0±0 MPa) cements. When the mixtures were injected into a femur hole, the 2-week specimens revealed that the PP-salt/calcium-phosphate mixture was still in close contact with the bone. At 5 and 8 weeks, mixture-remnants could still be observed in the cavity holes, but the holes of the 8-week specimens became smaller than those of the 5-week specimens. For all specimens, the mixture was completely surrounded with regenerated bone. Conclusion: In vitro and in vivo studies revealed good bone adaptation as well as bone regeneration, by which this PP-based bioadhesive appears promising to mechanically and functionally repair bone defects.