AIM: To immobilize dental pulp stem cells (DPSC) in alginate microspheres and to 
determine cell viability, proliferation, stem cell characteristics and 
osteogenic potential of the immobilized DPSCs.
METHODOLOGY: Human DPSCs isolated from the dental pulp were immobilized in 1% 
w/v alginate microspheres. Viability and proliferation of immobilized DPSCs were 
determined by trypan blue and MTT assay, respectively. Stem cell characteristics 
of DPSCs post immobilization were verified by labelling the cells with CD73 and 
CD90. Osteogenic potential of immobilized DPSCs was assessed by the presence of 
osteocalcin. Alizarin red staining and O-cresolphthalein complexone method 
confirmed and quantified calcium deposition. A final reverse transcriptase PCR 
evaluated the expression of osteogenic markers - ALP, Runx-2 and OCN.
RESULTS: More than 80% of immobilized DPSCs were viable throughout the 3-week 
study. Proliferation appeared controlled and consistent unlike DPSCs in the 
control group. Presence of CD73 and CD90 markers confirmed the stem cell nature 
of immobilized DPSCs. The presence of osteocalcin, an osteoblastic marker, was 
confirmed in the microspheres on day 21. Mineralization assays showed high 
calcium deposition indicating elevated osteogenic potential of immobilized 
DPSCs. Osteogenic genes- ALP, Runx-2 and OCN were also upregulated in 
immobilized DPSCs. Surprisingly, immobilized DPSCs in the control group cultured 
in conventional stem cell media showed upregulation of osteogenic genes and 
expressed osteocalcin.
CONCLUSION: Dental pulp stem cells immobilized in alginate hydrogels exhibit 
enhanced osteogenic potential while maintaining high cell viability both of 
which are fundamental for bone tissue regeneration.