A novel PTH-derived peptide, PTHdP,
including a repetitive aspartic
acid sequence at the C-terminal and phosphorylated serine at the N-terminal
has been previously designed. To evaluate its potential as a bone
growth factor for bone tissue engineering, true bone ceramics incorporated
with nanohydroxyapatite coating and chitosan (CH/TBC) was developed
as a desired three-dimensional porous delivery carrier in this study.
In vitro results showed that PTHdP could be loaded with high-efficiency
and subsequently released in a controlled and sustained manner from
CH/TBC. Bioactivity of released PTHdP was retained and able to exert
a significant effect on promoting or inhibiting osteogenesis actions
when exposed intermittently or continuously, respectively, for MC3T3-E1
cell culture. As evaluated in a critical-size rabbit radial defect
model by radiographic and histological examination, the combination
of CH/TBC scaffolds with PTHdP exhibited a remarkably stronger capacity
to stimulate new bone formation than control and pure CH/TBC groups.
These results indicated the novel PTHdP peptide achieved high affinity
to bone mineral without interference in bioactivity, and local delivery
of PTHdP from apatite materials could be a promising alternative for
future bone tissue engineering.