Periodontal healing with a preameloblast-conditioned medium in dogs

Background and Objective The predictability of conventional periodontal treatments for damaged periodontal tissue is limited, particularly on the regeneration of new cementum. As signaling molecules, a range of growth factors has been used to promote periodontal regeneration on periodontal ligament (PDL) and cementum defects. A preameloblast‐conditioned medium (PA‐CM) was prepared from cultured murine apical bud cells, which can differentiate into ameloblasts. We examined the effect of PA‐CM on PDL cells and cementoblasts in vitro and evaluated histologically the effects of PA‐CM on the regeneration of experimentally induced periodontal defects in vivo. Material and Methods In vitro, the effects of PA‐CM on the migration of human PDL cells were examined using a scratch wound healing assay and a transwell assay. The differentiation and mineralization potential of PA‐CM‐treated human PDL cells and murine cementoblastic OCCM‐30 cells was examined by real‐time polymerase chain reaction and Alizarin red‐S staining. In vivo, six mongrel dogs (12–16 kg; 6–8 mo old) were used. Twenty‐four roots were replanted with either, (i) only periodontal defects (n = 12; control group), or (ii) periodontal defects and PA‐CM treatment (n = 12; experimental group). In the experimental group, the PDL and cementum between notches was removed using a Gracey curette and soaked in 0.08 mL water containing 80 μg of a PA‐CM for 2 min. The dogs were killed at 4 and 8 wk post‐surgery. Results The in vitro results showed that PA‐CM stimulated the migration of PDL cells and promoted the differentiation and mineralization of PDL cells and cementoblasts. Real‐time polymerase chain reaction analysis revealed stronger expression of Runx2, Osx, OC, Bsp and Cap mRNAs in the PA‐CM‐treated PDL cells and cementoblasts than those in the control cells. In vivo, newly formed PDL‐like tissue and cementum‐like tissue were observed partially between the root surfaces and newly formed bone in the experimental group. The regenerated PDL‐like tissue in the experimental group was significantly higher than that in the control group at 8 wk (p