Aim. This study aimed to evaluate the immunogenicity of the Nano Graft biomaterial in biopsies obtained from the maxillary sinus augmentation zone using morphological and immunohistochemical assessment of the cellular response.

Materials and methods. The study included 22 patients with partial posterior edentulism who underwent open maxillary sinus floor elevation using the Nano Graft biomaterial. Biopsy samples collected at the time of implant placement were fixed, decalcified, and processed for histological and immunohistochemical analysis with the following markers: CD8 (cytotoxic T lymphocytes), FOXP3 (regulatory T cells), CD68 (macrophages/osteoclasts), CD163 (M2 macrophages), SATB2 (osteogenic cells), and CD34 (endothelial cells). Inflammatory activity was assessed using a semi-quantitative scale.

Results. Histological examination revealed fibrous connective tissue containing fibroblasts, microvascular structures, and signs of osteon formation and bone remodeling. Immunohistochemistry demonstrated a low-grade lymphohistiocytic infiltrate with scarce CD8+ cells and no detectable FOXP3+ regulatory T cells, indicating the absence of a pronounced immune response. An abundant presence of CD163+ M2 macrophages suggested polarization toward a regenerative phenotype. Strong SATB2 expression confirmed osteoinductive activity, while numerous CD34+ endothelial cells indicated active angiogenesis.

Conclusions. The Nano Graft biomaterial exhibited low immunogenicity, characterized by a mild CD8+ T-cell response, absence of FOXP3+ regulatory T cells, and predominance of anti-inflammatory M2 macrophages. Its osteogenic potential and pro-angiogenic effects support its biocompatibility and clinical applicability for maxillary sinus augmentation.