Stem cells in regenerating human periodontal tissues and cadaver tissues

Stem cells isolated from human periodontal ligament (PDLSCs) have been shown to participate in wound healing in animals. However, the role of PDLSCs in periodontal wound healing in humans is unclear. It is also unknown if cadaver tissues are a useful model to study stem cells in the periodontium. Objective: Our aim was to identify and localise putative stem cells in regenerating human periodontal tissues and cadaver tissues, and assess cell-surface expression and differentiation potential of cultured cells from regenerating tissues in vitro. Methods: Guided tissue regeneration procedures were carried out on three human volunteers around teeth destined for extraction. After six weeks, the teeth were surgically removed with their surrounding regenerating tissues and processed for immunohistochemistry. Antibodies against STRO-1, CD146 and CD44 – known markers of mesenchymal stem cells (MSCs) – were used to identify putative MSCs in both regenerating and cadaver tissues. Cultured regenerating tissue cells were analysed by flow cytometry as well as mineralisation and adipogenic assays. Results: STRO-1+ and CD44+ cells were identified in both regenerating and cadaver tissues, but CD146+ cells were only present in regenerating tissues. Cultured regenerating tissue cells expressed all three MSC markers and produced mineralised and lipid deposits in vitro. Conclusion: Cells with characteristics of MSCs were found in regenerating periodontal tissues. This finding provides first evidence of the involvement of stem cells in human periodontal wound healing and offers support to their use in regenerative periodontal therapy. However, cadaver tissues present a limited model for studying stem cells in the periodontium.