Antlerogenic stem cells: molecular features and potential in rabbit bone regeneration

(i) To assess the expression profiles of stem cell-associated markers including Oct4, Sox2, Klf4, Nanog, C-myc, Stat3 and Cd9, (ii) analyze the nanotopography of the MIC-1 stem cells and (iii) evaluate the efficiency of live stem cell implants and stem cell culture derivatives on the regeneration of bone deficiencies in rabbit mandibles.

The expression profiles of stem cell-associated genes, including Oct4, Sox2, Klf4, Nanog, C-myc, Stat3 and CD9 were assessed using reverse transcription polymerase chain reaction and flow cytometry. Nanotopography of the antlerogenic MIC-1 cell lineage was analyzed using atomic force microscopy. The effect of MIC-1 stem cells, their homogenate and supernatant on the regeneration of bone deficiencies in rabbit mandibles was evaluated using histological analysis. The effect of MIC-1 stem cells and stem cell-based derivatives on the immune responses of the animals was assessed by analyses of acute phase protein levels (haptoglobin and fibrinogen).

We found that the MIC-1 cells isolated from the apical regions of growing antlers exhibited molecular features that were characteristics of pluripotent stem cells. Using atomic force microscopy, we determined the details of the cell surface morphologies with a particular emphasis on the patterns of formation of plasma extensions for interlinking adjacent cells. We also demonstrated that not only implanted stem cells but also cell homogenates and cell post-culture supernatants have potential in the regeneration of bone deficiencies in the rabbit mandible.

Our findings indicate that the use of both antlerogenic stem cell implants and the preparations derived from the cells offer alternative approaches to those based on autologous stem cells in the biological stimulation of osteogenesis and in bone regeneration.