# Platelet Secretome Drives Mitogenic and TGF-β Responses in Gingival Fibroblasts

## TL;DR

This study shows that platelets in PRF are key to promoting gum tissue healing by activating growth and repair pathways without causing inflammation.

## Contribution

The study isolates platelet-derived factors to demonstrate their direct role in PRF's biological effects, independent of leukocytes and plasma.

## Key findings

- Platelet-released factors strongly upregulate genes related to cell growth and cytokine production in gingival fibroblasts.
- Platelet-derived factors activate TGF-β signaling without inducing inflammatory NF-κB signaling.
- PRF's healing effects are primarily driven by platelets, not leukocytes or plasma components.

## Abstract

Platelet-rich fibrin (PRF) is commonly used in dentistry and oral surgery to enhance wound healing and tissue regeneration. PRF is prepared from blood and contains a mixture of platelets, white blood cells, and plasma proteins, making it difficult to determine which component is primarily responsible for its healing effects. The aim of this study was to clarify the specific role of platelets. To achieve this, we isolated platelets, removed white blood cells, and collected the substances released by activated platelets. These platelet-derived factors were applied to gingival fibroblasts, which are cells essential for gum tissue repair. We found that platelet-derived factors strongly stimulated genes involved in cell growth and increased the production of molecules known to support healing. Importantly, these factors activated a key repair-related signaling pathway without triggering excessive inflammation. In conclusion, platelets play a central role in the biological effects attributed to PRF.

Platelet-rich fibrin (PRF) is widely used in regenerative dentistry and oral surgery for its ability to promote tissue healing and modulate cellular responses. However, PRF contains not only platelets but also leukocytes and plasma components, complicating efforts to define the specific contribution of platelets to its biological activity. To address this, we used washed, leukocyte-depleted platelets activated with thrombin to generate platelet-released supernatant (PRS), which was applied to gingival fibroblasts. RNA sequencing identified 147 upregulated and 39 downregulated genes (|log2 fold change| ≥ 2, FDR < 0.001), including cytokines IL11 and CXCL8 previously associated with PRF, as well as mitosis-related genes such as centromere-associated proteins, cell division cycle proteins, kinesin-like proteins, and shugoshins, consistent with gene ontology analyses. Validation by RT-PCR and immunoassays confirmed robust upregulation of IL11 and CXCL8. Functionally, PRS activated TGF-β signaling, indicated by Smad2/3 nuclear translocation, but did not induce NF-κB signaling. These findings demonstrate that platelets are major contributors to PRF’s biological effects, independent of leukocytes and plasma, and elicit a pronounced mitogenic and TGF-β-dominant response in gingival fibroblasts. They also provide insight into the cellular mechanisms underlying PRF-mediated tissue regeneration.