Regeneration of dental pulp following pulpectomy by fractionated stem/progenitor cells from bone marrow and adipose tissue

Pulp stem/progenitor cells can induce complete pulp regeneration. However, due to the limited availability of pulp tissue with age, there is a need to examine other sources for fractions of side population (SP) cells. In the present investigation bone marrow and adipose tissues of the same individual were evaluated as alternate sources. Pulp CD31− SP cells have higher migration activity and higher expression of angiogenic/neurotrophic factors than bone marrow and adipose CD31− SP cells. Adipose tissue CD31− SP cell transplantation yielded the same amount of regenerated tissue as pulp derived cells. However, bone marrow CD31− SP cell transplantation yielded significantly less regenerated tissue in pulpectomized root canals in dogs. The rate of matrix formation was much higher in adipose CD31− SP cell transplantation compared to pulp CD31− SP cell transplantation on day 28. Microarray analysis demonstrated similar qualitative and quantitative patterns of mRNA expression characteristic of pulp in the regenerated tissues from all three cell sources. Expression of many angiogenic/neurotrophic factors in the transplanted cells demonstrated trophic effects. Our results demonstrate that bone marrow and adipose CD31− SP cells might be suitable alternative cell sources for pulp regeneration.