Characterization of regenerated tissue on day 28 in an ectopic tooth root transplantation model. a, f, k, o, t Transplant of pulp CD31− side population (SP) cells (Pulp SCs). b, g, l, p, u Transplant of conditioned medium (CM) from pulp CD31− SP cells (Pulp CM). c, h, m, q, v Transplant of CM from bone marrow CD31− SP cells (BM CM). d, i, n, r, w Transplant of CM from adipose CD31− SP cells (AD CM). a-d Immunostaining with rat endothelial cell antigen 1 (RECA1). e Ratio of vascularization area to the total regenerated area. (f-i) In situ hybridization analysis of expression of thyrotropin-releasing hormone-degrading enzyme (TRH-DE) as a pulp marker using an anti-sense probe reactive to both porcine and mouse genes. j Protein expression of TRH-DE in regenerated pulp after transplantation of CM from pulp, bone marrow (BM), and adipose (AD) CD31− SP cells. k-s Odontoblastic differentiation potential in the regenerated pulp. k-n Odontoblastic cells along with the dentinal wall. o-r In situ hybridization analysis of enamelysin. Odontoblastic process extending into the tubular dentin (arrows). s Comparison of the numbers of enamelysin-positive cells along the dentinal wall. t-w Immunostaining with aggrecan (green) merged with Hoechst 33342 (Blue). x Ratio of aggrecan-positive area to the total regenerated area. Data are expressed as mean ± standard deviation of four determinations. *P < 0.05, **P < 0.01