Schneiderian membrane adult vasculogenesis evaluated by CD31 and CD34 expression and morphological arrangement

Background. Few studies approached the process of blood vessels formation in the Schneiderian membrane. We aimed at investigating by immunohistochemistry the processes that are responsible for forming new blood vessels in the human Schneiderian membrane.

Material and methods. We applied CD31 and CD34 markers on bioptic samples gathered from eight adult patients negative for malignant pathologies. Filopodia-projecting endothelial tip cells (ETCs) were found and indicated processes of sprouting angiogenesis. Also, CD31-expressing monocyte-derived cells were found being involved in processes of vasculogenesis. These cells were projecting filopodia, thus being assessed as endothelial progenitor tip cells (EpTCs). Aggregates of CD31+ EpTCs were also analyzed. Further stages of lumen acquisition and large diameter vessels formation, specific for vasculogenesis, were evaluated.

Results. It resulted that, specifically within the maxillary sinus mucosa, vascular remodelling is equally ensured by adult vasculogenesis and sprouting angiogenesis.

Conclusion. This is, to our knowledge, the first evidence of adult vasculogenesis in the maxillary sinus mucosa, supported by bona fide bone marrow-derived CD31+ cells. The guidance mechanism of EpTCs protrusions needs further investigations for finding similarities, or dissimilarities, with the endothelial tip cells prolongations.