[Specific markers and ultrastructure of lymphatic vessel in healthy human dental pulp]

To explore the existence of lymphatic vessels in healthy human dental pulp.

Thirty healthy human dental pulps were obtained from non-carious premolars removed for orthodontic reasons. Immunohistochemistry was performed using the antibodies specific for lymphatic endothelium such as D2-40 and LYVE-1, and for vascular endothelial cell such as CD31 and CD34. The expression of D2-40 was detected by Western blotting and ultrastructure was examined by transmission electron microscopy.

In healthy human dental pulps, we failed to detect any reactivity for the lymphatic markers D2-40 and LYVE-1 in the observed vessels. These vessels were positive stained by blood endothelial markers CD34 and CD31. Odontoblasts were weakly stained with D2-40. Western blotting performed on collagenase-treated human dental pulps did not show a band at 40 kDa, corresponding to the molecular weight of the lymphatic marker D2-40. Transmission electron microscopy indicated that vessels in dental pulp consisted of endothelial monolayer surrounded by pericytes and complete basement membrane, which were typical ultrastructural characteristics of blood vessels rather than lymphatic vessel.

Human dental pulp does not contain true lymphatic vessels under healthy conditions. Whether lymphatic system is involved in dental pulp interstitial fluid circulation during inflammation deserved further study. Supported by National Natural Science Foundation of China (81100768) and Key Project Supported by Medical Science and Technology Development Foundation, Department of Health of Nanjing City (YKK11040 and QRX11123).