Role of Osteogenically Differentiated and Undifferentiated Stem Cells From Adipose Tissue and Bone Marrow On Bone Regeneration In Critical Sized Calvarial Defects

Background:

The aim of this study was to examine the role of adipose-derived and bone marrow-derived stem cells and osteoblasts differentiated from these stem cells on bone regeneration.   

Materials and methods:

Stem cells were provided from bone marrow and adipose tissue of the rats and osteogenically differentiated (1). Fluorescent labelled (CM-DiI) cells (2) were seeded onto gelatin carrier (3). 48 rats were equally divided into 6 groups (n=8) and critical sized (8 mm) cranial defect model was used (4). Group 1 had only cranial defect while group 2 recieved gelatin carrier without cells seeded onto. Groups 3 and 4 recieved osteoinduced and non-induced stem cells from adipose tissue and group 5 and 6 recieved osteoinduced and non-induced stem cells derived from bone marrow. Cranial defects were measured with computerized tomography (CT) at 0, 2nd, 4th and 8th weeks postoperatively. Rats were sacrificed at 8th week postoperatively and specimens underwent histological analysis. Stem cells with CM-DiI were  visualised. Immunohistochemical labelling with osteocalcin and vWF were performed.

Results:

There was no significant difference between cranial defects of cell-based therapy groups (groups 3, 4, 5 and 6) and those of control and carrier groups (groups 1 and 2) at 0, 2nd and 4th weeks (p>0.05), while there was a significant difference at 8th week (p<0.05). There was no significant difference between cell-based therapy groups when compared to each other in 0, 2nd, 4th and 8th weeks (p>0.05). Histologically, cell-based therapy groups exhibited  new bone islands. The existence of the stem cells in the cranial defect site was confirmed at 8th week postoperatively with fluorescent dye and viable osteoblastic and endothelial cells in the newly formed bone were displayed immunohistochemically.

Conclusion:

In our study, cell-based therapy groups proved to have more osteogenic potential compared with the control and carrier groups. There was no significant difference in terms of new bone formation between the osteogenically induced and non-induced stem cells from bone marrow and adipose tissue. Based on previous scientific data, stem cells can differentiate into osteoblasts when needed as well as endothelial cells to support vascular supply to the newly formed bone. We demonstrated that osteogenic differentiation was not a necessity for stem cells and adipose tissue was the preferred source with advantages of high yield and rapid expansion.