Expression of Matrilin-2 and-4 in Human Dental Pulps during Dentin-Pulp Complex Wound Healing

Introduction: Matrilin-2 and matrilin-4 are members of the matrilin family displaying broad tissue distribution. We recently reported that matrilin-2 showed significant down-regulation during the odontogenic differentiation of dental pulp cells (DPCs). It is reported that matrilin-4 was the only extracellular matrix biogenesis and organization-related gene detected in odontoblasts but not DPCs. However, the exact role of matrlin-2 and -4 in dental pulps remains unclear. The aim of our study was to analyze the expression of matrilin-2 and -4 in human dental pulps and their relation to dentin-pulp complex wound healing. Methods: Immunohistology was performed on the paraffin-embedded tissue sections of human dental pulps from sound and deep carious teeth. Matrilin-2 and -4 messenger RNAs were detected by quantitative real-time reverse-transcription polymerase chain reaction, and the proteins were shown by immunofluorescence and Western blot during odontogenic differentiation of the DPCs. Results: In the sound dental pulp, matrilin-2 immunoreactivity was observed throughout the pulp, whereas matrilin-4 was observed only in the odontoblast layer. In deep carious dental pulp, matrilin-2 protein was weakly stained, whereas matrilin-4 was detected in the pulp under the carious lesion. During odontogenic differentiation of DPCs, the expression of matrilin-2 messenger RNA was down-regulated within 14 days followed by a statistical increase on day 21, and the matrilin-2 protein level was down-regulated within the 3 weeks, whereas the messenger RNA and protein expressions of matrilin-4 increased in a time-dependent manner. Conclusions: Matrilin-2 and matrilin-4 have been shown in human dental pulps and might be involved in the dentin-pulp complex wound-healing process. (J Endod 2011;37:642-649)