Dental pulp progenitor cells (DPPCs) are among many stem cell sources potentially beneficial for tissue engineering. DPPCs offer advantages over other mesenchymal stem cell sources, due to their accessibility and multi-lineage differentiation. However, distinct DPPC clones exist within dental pulp, with contrasting proliferative/regenerative capabilities. This is a key consideration for the exploitation of DPPCs, in terms of the abilities of isolated clones to undergo sufficient in vitro proliferative expansion, while maintaining their regenerative potential. This Thesis supports the heterogeneous nature of DPPCs, demonstrating significant variations in population doublings (PDs) and senescence, with highly proliferative clones exhibiting greater proliferation (>80PDs) under normal and oxidative stress (H2O2 treatment) conditions, compared to low proliferative clones (<40PDs) demonstrating altered morphology, increased SA-β-galactosidase staining and senescence marker (p53/p16) expression. Although negative for human telomerase expression, highly proliferative clones possessed longer telomeres (>18kb); maintained stem cell marker expression (CD73, CD90, CD105) and osteogenic/chondrogenic differentiation in culture. In contrast, low proliferative clones exhibited shorter telomeres (<6kb), reduced marker expression and increased adipogenesis. DPPC heterogeneity was further evident upon Raman Spectroscopy analysis, which distinguished between undifferentiated high and low proliferative clones and undifferentiated DPPCs and clones following chondrogenic differentiation. High and low proliferative clonal behaviour was also assessed in type I collagen gels, demonstrating increased contraction and reduced cell proliferation in detached versus attached gels, irrespective of clonal type. Increased contraction was due to increased MMP-2 expression by both clonal types, while highly proliferative clones also expressed MMP-9, especially at late PDs. These findings indicate significant variations in DPPC clonal proliferative/differentiation capabilities, partly explained by telomere length/cellular ageing differences. Identification of clonal populations with contrasting tissue regeneration capacities supports the development of screening strategies (e.g. Raman Spectroscopy) for the selective isolation of highly proliferative clones from dental pulp for therapeutic use, or assessing DPPC differentiation in 3D culture.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:585331 |
| Date | January 2013 |
| Creators | Alraies, Amr |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/53906/ |
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