08 December 2023

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How dental pulp changes based on age

Lara Figini

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Literature studies report that the blood vessels in different organs or even in different tissues are not all the same but are heterogeneous, classifiable into various subtypes (type H, type L and type E vessels, VEGFR3+CD34− VEGFR2+CD45 vessels − in the liver, and CD31hiEmcn+ESM-1+ vessels in the islets of the pancreas etc.).

These specific blood vessel subtypes usually regulate perivascular cell/tissue function through angiocrine effects.

Already in 1992, a study by Vongsavan reported that the dental pulp in cats is more vascularized than most other organs. Blood vessels are fundamental in the regeneration of the dental pulp, so much so that many recent studies have focused their attention on the reconstruction of the vascularization of the pulp through tissue engineering.

Recently, a study based on single cell sequencing demonstrated that dental pulp vascular endothelial cells could be classified into three subpopulations (Krivanek, 2020).

However, the distribution pattern of specific vascular subtypes of the dental pulp and its perivascular parts and the mapping of the microenvironment is still poorly studied.

In organs/tissues such as the kidney, spleen and muscles, blood vessels show a significant age-dependent decrease, while in tissues with a high turnover rate, such as the skin, there is no obvious change with age. time. However, age-related dental pulp vascular changes in mice and humans remain poorly understood.

In an in vitro study, published in the September 2023 Journal of Dentistry, the authors analyzed age-related dental pulp vascular changes present in mice and humans. The authors developed a new tissue removal method and mapped the vasculature, pericytes and perivascular matrix in the dental pulp via high-resolution 3D imaging.

Young and aged pulps were isolated from mouse teeth, and the vasculature was mapped through a high-resolution section imaging method and a modified tissue clearing method. Human dental pulps and their vasculature were also mapped for study. Young and aged human dental pulps were collected and compared to mouse pulps through RNA sequencing.

Results

Five vascular subtypes of blood vessels were found in the dental pulp of mice, which constituted the arteriole-capillary-venule network. The density of molar capillaries and venules was decreased in aged mice. Among the age-dependent changes in the perivascular pulp matrix, perivascular macrophages were significantly increased, lymphatic capillaries increased, while nerves and extracellular matrix remained unchanged. Furthermore, human vascular patterns formed a complex vascular network. Both human and mouse dental pulps showed an inflammatory state. The TNF pathway and the Rap1 pathway could become promising targets to fight inflammation and promote angiogenesis.

Conclusions

From the data of this study, which must be confirmed in other similar works, it can be concluded that there are five subtypes of blood vessels identified in the dental pulp of mice. In particular, the density of capillaries and venules in the pulps of aged mice is reduced. Furthermore, partial similarities in vascular patterns were observed between the dental pulps of humans and mice.

RNA sequencing analysis revealed that both mouse and human dental pulps show signs of inflammatory state.