Immunohistochemical analysis of growth factors in platelet-rich fibrin membranes

The use of autogenous materials to promote tissue regeneration has guided the direction of modern dentistry, and platelet-rich fibrin (PRF) is a promising biomaterial for tissue engineering. This in vitro immunohistochemical study aimed to analyze the presence of factors of endothelial growth and cell differentiation in PRF membranes by using the CD31 (endothelial cells) and CD163 (monocytes) markers. Five men and 5 women, aged between 25 and 60 years and without systemic health problems, were enrolled in the study. Blood samples were collected, submitted to a centrifugation protocol, and fixed in 4% formaldehyde, and then immunohistochemical analysis was performed. The histologic analysis of the slides showed that the fibrin clot was formed by a dense fiber network and cells trapped in its structure. One sample was excluded from the markers testing due to poor quality. All 9 of the valid samples were positive for the CD31 and CD163 markers, with reactivity ranging from 5% to 30% and 10% to 40% of cells, respectively. The immunohistochemical analysis showed the presence of CD31 and CD163 in the PRF membranes, indicating the potential for vascular neoformation and the significant presence of monocytes, which play an important role in tissue remodeling via their differentiation into macrophages.