The Validity of Nano-chitosan/ Nano-Hydroxyapatite as a Promoter of Bone Healing in Ovariectomized Rats

Background: Nano-hydroxyapatite (nHA) is a biomaterial successfully used in bone tissue engineering. As well, Nano-chitosan (nCTS) is one of the natural polymers used in tissue engineering research. The unique properties of nCTS/nHA composite materials have attracted research interest especially in bioapplications. Estrogen deficiency is responsible for osteoporosis which is a metabolic bone disease characterized by delayed bone healing.
Aim of study: to investigate the putative effect of nCTS/nHA combination on the healing of bony defects in experimental postmenopausal hypoestrogenic rat model.
Materials and Methods: Forty eight, 6 month old, virgin female rats were randomly allocated into four equal groups; ovariectomy (OVX), Sham, OVX- nCTS/nHA treated, and Sham- nCTS/nHA treated groups. Sixty days following OVX or Sham surgery, a critical-sized defect on the right side of mandible was created in all groups then filled with nCTS/nHA hydrogel only in the third and fourth groups. Two and four weeks following bony defect surgery, six animals per group were euthanized and bone samples were processed for light microscopic (LM) examination, X-ray elemental microanalysis and scanning electron microscopic (SEM) examination.
Results: LM and SEM examinations of OVX group revealed delayed bone healing during both experimental periods in comparison with other groups. Interestingly, application of nCTS/nHA revealed improvement in bone healing process. X-ray elemental microanalysis of OVX group depicted marked significant decrease in calcium level below those of other groups. However, using nCTS/nHA revealed significant increase in calcium level suggesting its augmenting role in bone mineralization.
Conclusion: Estrogen deficiency impaired bone healing process. However, the synergistic effect of nCTS / nHA has the ability to improve the impaired bone healing in rats with OVX-induced osteoporosis.
Key words: Nano-hydroxyapatite, Nano-chitosan, Ovariectomy, Estrogen deficiency, Bone healing
Abbreviations: nHA: Nano-hydroxyapatite; nCTS: Nano-chitosan; OVX: ovariectomy;
LM: light microscope; SEM; scanning electron microscope.