3d human epidermal model in vitro to assess the effects of boron neutron capture therapy on keratinocytes poliferation

oron Neutron Capture Therapy (BNCT) is an innovative radiotherapy for treating solid tumors unresponsive to traditional therapies. The administration of a compound labelled with boron-10 (10B, non-radioactive) is a pre-treatment, followed by irradiation with low-energy neutrons. The neutron beam penetrates the patient across the skin, making it a limiting tissue. It thus needs to study the dose-effect relation in the skin. [1, 2, 3] The SkinEthicTM model, an in-vitro reconstructed human epidermal model, was used for this purpose. Several studies [4] have confirmed the reliability of its response compared to the native tissue. Samples were incubated with boronophenylalanine (BPA), a 10B delivery agent, and irradiated at three different power levels: 4.5, 11.4 and 22.7 Gy. Models were fixed at subsequent observation times, embedded in paraffin, and sliced. The percentage of proliferating cells was assessed using Bromo-Deoxy-Uridine incorporation assay (BrdU) and the expression of Proliferation-Cell Nuclear Antigen (PCNA). Same analyses were performed on constructs irradiated both with the neutron beam without BPA and with a photon beam to evaluate BNCT's effectiveness. Morphological and immunohistochemical analyses showed progressive changes in the tissue structure of the constructs over time and in response to radiation doses. The cell proliferation activity varied, with low BrdU-positive-cells in samples treated with BNCT for 2 days. The anti-PCNA assays also showed variable positivity trends, peaking on the second day in culture. The reduction of proliferating cells was linked to a high presence of protein involved in reparative mechanisms, consistent with previous in-vitro studies. These preliminary experiments aim to refine the study protocol and improve the characterization of constructs and their responses to radiation. The high variability in results makes the standadization difficult, suggesting the need to increase sample number for statistically significant results. Observations at shorter times and lower radiation doses would complete this dose-effect study.