Histological analysis of dental pulp response in immature or mature teeth after extra-oral subcutaneous transplantation into mice dorsum

Abstract

The aim of this study was to assess the response of dental pulp associated with donor or host cells in the pulp chamber and root canal after extra-oral transplantation. Methods: Wild type or green fluorescent protein (GFP) transgenic first molars from 3-week, 6-week, and 12-week mice were transplanted into the subcutaneous layer of GFP mice or wild type mice. The teeth were histologically and immunohistochemically examined at 5 weeks after transplantation. Results: Blood vessels present in the original coronal pulp had anastomosed with those from the recipient tissue that had invaded the root canal. Two distinct eosin-stained extracellular matrices were observed in the pulp chamber and root canal. Acellular matrix composed of nestin-positive, odontoblast-like cells invaded from the outside and was seen in the root canal of 3-week teeth. Cellular matrix comprising alkaline phosphatase (ALP)-positive fibroblast-like cells appeared in the original coronal pulp. In the root canal of the 6-week and 12-week teeth, cellular extracellular matrix consisting of ALP-positive fibroblast-like cells had invaded the recipient tissue. Conclusion: Dental pulp from immature teeth might be able to regenerate dentin-like tissue. This model could be useful in the development of an optimized vitalization treatment.

Dental Pulp Cell Transplantation Combined with Regenerative Endodontic Procedures Promotes Dentin Matrix Formation in Mature Mouse Molars

“…The REP was performed on the mandibular first molars of 10-week-old C57BL/6 mice in a similar manner as described previously [44] with some modifications. In previous study, radiographic analysis showed that the roots reached maturity by weeks [45]. The mice were subject to general anesthesia via intraperitoneal injection mixture of medetomidine hydrochloride (0.75 mg/kg; Dormitor, Zenoaq, Fukush Japan), midazolam (4.0 mg/kg; Sandoz, Novartis, Basel, Switzerland), and butorph tartrate (5 mg/kg; Meiji Seika Pharma, Chuo City, Tokyo, Japan).…”

“…To examine the effectiveness of the REP treatment, in vivo µCT analyses were performed at 1, 2, 3, and 4 weeks after the treatment, as previously described [45]. Briefly, µCT images of the first mandibular molar were obtained under deep anesthesia (Cosmo Scan GX; Rigaku Corp., Tokyo, Japan) using the following parameters: 4 min, 90 kV, and 100 mA.…”