Abstract
Periodontal ligament mesenchymal stem cells (PDLMSCs) are an important alternative source of adult stem cells and may be applied for periodontal tissue regeneration, neuroregenerative medicine, and heart valve tissue engineering. However, little is known about the impact of bacterial toxins on the biological properties of PDLSMSCs, including self-renewal, differentiation, and synthesis of extracellular matrix. Objective: This study investigated whether proliferation, expression of pro-inflammatory cytokines, and osteogenic differentiation of CD105-enriched PDL progenitor cell populations (PDL-CD105+ cells) would be affected by exposure to bacterial lipopolysaccharide from Escherichia coli (EcLPS).Material and Methods : Toll-like receptor 4 (TLR4) expression was assessed in PDL-CD105+ cells by the immunostaining technique and confirmed using Western blotting assay. Afterwards, these cells were exposed to EcLPS, and the following assays were carried out: (i) cell viability using MTS; (ii) expression of the interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF-α) genes; (iii) osteoblast differentiation assessed by mineralization in vitro, and by mRNA levels of run-related transcription factor-2 (RUNX2), alkaline phosphatase (ALP) and osteocalcin (OCN) determined by quantitative PCR.Results : PDL-CD105+ cells were identified as positive for TLR4. EcLPS did not affect cell viability, but induced a significant increase of transcripts for IL-6 and IL-8. Under osteogenic condition, PDL-CD105+ cells exposed to EcLPS presented an increase of mineralized matrix deposition and higher RUNX2 and ALP mRNA levels when compared to the control group.Conclusions : These results provide evidence that CD105-enriched PDL progenitor cells are able to adapt to continuous Escherichia coli endotoxin challenge, leading to an upregulation of osteogenic activities.
Highlights
The great differentiation capacity of mesenchymal stem cells (MSCs), the possibility of grafting, and its expansion in culture led to an increased interest in the clinical use of these cells through directed administration on specific sites in many pathological situations
Periodontal ligament mesenchymal stem cells (PDLSCs) can be routinely isolated and cultivated from periodontal ligament, many issues have to be approached before these cells can be used for therapies, such as their growth and differentiation in the presence of bacterial toxins, which may be present in many clinical situations
periodontal dental ligament (PDL)-CD105+ cells exhibited positive staining for Toll-like receptor 4 (TLR4), which is a specific molecule involved in E. coli LPS signaling pathways (Figures 2A and 2B)
Summary
The great differentiation capacity of mesenchymal stem cells (MSCs), the possibility of grafting, and its expansion in culture led to an increased interest in the clinical use of these cells through directed administration on specific sites in many pathological situations. In this sense, regenerative therapy based on stem cells has gained attention since the isolation of mesenchymal stem cells from various tissues. Dental tissue is a potent reservoir of postnatal stem/progenitor cells isolated from dental pulp[4], periodontal ligament from permanent[21] and deciduous teeth[22], apical papilla[24], or dental follicles[17] PDLSCs can be routinely isolated and cultivated from periodontal ligament, many issues have to be approached before these cells can be used for therapies, such as their growth and differentiation in the presence of bacterial toxins, which may be present in many clinical situations
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