Age-related differences in expression of vascular endothelial growth factor by periodontal ligament cells in vitro

Histological evaluation of the periodontal ligament from aged wistar rats supplemented with ascorbic acid

Ascorbic acid (AA) is able to neutralize reactive oxygen species and is essential for collagen synthesis. In aging process oxidative stress is elevated. This study aims to investigate the effects of AA supplementation on the periodontal ligament (PL) of rats during aging. Twenty five rats were used and divided into groups: J90 (90-day-old control), E345 (345-day-old control), E428 (428-day-old control), EA345 (345-day-old supplemented with AA from 90-day-old on) and EA428 (428-day-old supplemented with AA from 90-day-old on). We analyzed the thickness, density of fibroblasts and blood vessels and collagen fibers types in the PL. In group J90 there was predominantly type III collagen fibers (87.64%). In animals supplemented with AA, the area filled by type I fibers (group EA345: 65.67%, group EA428: 52.23%) was higher than type III fibers. PL in group EA428 was thicker than the one observed in group E428 (P < 0.05). During natural aging process, AA promoted the maturation of collagen fibers and enhanced angiogenesis in periodontal ligament. One can conclude that the supplementation with AA represented a beneficial factor for the development of PL in aged rats.

Regenerative capability of dental pulp cells after crown fracture

The purpose of this study was to evaluate the characteristics of dental pulp cells for tissue engineering derived from the fractured incisal portion of tooth crowns. Thirty Sprague-Dawley rats were used for histological and immunohistochemical analysis of nestin protein expression and to measure levels of mRNAs encoding osteocalcin, osteopontin, bone sialoprotein (BSP), dentin sialoprotein (DSP), heat shock protein (HSP) 27, vascular endothelial growth factor (VEGF), ATP-binding cassette transporter G2 (ABCG2), nestin, and p57(Kip2) . Odontoblasts at the incisal portion in the control group were oriented in a regular pattern, but those in the experimental group were randomly stratified. Immunohistochemically, only a few odontoblasts were positive for nestin at the incisal portion in the experimental group at 2 days. Some cells in the inner area in the control group were positive for nestin, but nestin-positive cells in the experimental group at the incisal portion were not observed. The mRNA expression for osteogenic or odontogenic markers in the experimental group was higher than in the control group. HSP27 mRNA expression in the experimental group at 2 days was higher than in the control group and in the experimental group at 7 days. mRNA expression of stem cell markers, such as ABCG2 and nestin, in the experimental group tended to decrease compared with the control. In conclusion, this study demonstrates that dental pulp stem cells derived from fractured teeth differentiate to osteogenic or odontogenic cells.

Implications of cultured periodontal ligament cells for the clinical and experimental setting: a review

The periodontal ligament (PDL) is a key contributor to the process of regeneration of the periodontium. The heterogeneous nature of the PDL tissue, its development during early adulthood, and the different conditions to which the PDL tissue is exposed to in vivo impart on the PDL unique characteristics that may be of consequence during its cultivation in vitro. Several factors affecting the in vivo setting influence the behaviour of PDL fibroblasts in culture. The purpose of this review is to address distinct factors that influence the behaviour of PDL fibroblasts in culture -in vivo-in vitro transitions, cell identification/isolation markers, primary PDL cultures and cell lines, tooth-specific factors, and donor-specific factors. Based on the reviewed studies, the authors recommendations include the use of several identification markers to confirm cell identity, use of primary cultures at early passage to maintain unique PDL heterogeneic characteristics, and noting donor conditions such as age, systemic health status, and tooth health status. Continued efforts will expand our understanding of the in vitro and in vivo behaviour of cells, with the goal of orchestrating optimal periodontal regeneration. This understanding will lead to improved evidence-based rationales for more individualized and predictable periodontal regenerative therapies.