In vivo Bone Formation by Canine Mesenchymal Stem Cells Loaded onto HA/TCP Scaffolds: Qualitative and Quantitative Analysis

Objective: Biphasic ceramics of hydroxyapatite and three calcium phosphate (HA/ TCP) are increasingly being used as a bone substitute in regenerative surgery. To increase the bone forming capacities, HA/TCP Scaffolds could be enriched with osteogenic factor like mesenchymal stem cells (MSCs) which is the subject of present study. Materials and Methods: Passaged-3 culture-expanded MSCs of canines bone marrow were suspended in a diluted collagen gel and loaded onto commercially-available HA/TCP ceramics. The cell-loaded scaffolds were then autologously implanted along with the control cell-free scaffolds in masseter muscles of the four mongrel dogs. Eight weeks later, the parts of their muscles including the implants were prepared for a light microscopy. To quantify the amount of bone formation, the slides of both studied groups were photographed and the percent area of the newly formed bone was calculated using Image-Pro Plust software. Results: According to our observations, the implants were appeared to be encapsulated by fibrous tissue within the muscle. No cartilage tissues were observed in implantation site. Histological observation indicated that ectopic bone was formed in both MSCs-loaded scaffolds as well as the control cell-free implants. The percentage of newly formed bone for cell loaded HA/TCP scaffolds was %29.12±6.01 compared to %23.55±4.99 of the cell-free implants (p < 0.05). Furthermore, lamellar mature bone was only observed in cells/scaffold groups. Conclusion: Taken together, it seems that MSCs enhance bone formation capacity of HA/TCP. The formed bone following MSCs/scaffold composite implantation appeared to be histologically lymature lamellar bone.