Characterization of injectable nano-composite biomaterials with dual therapeutic/regenerative behaviors for bone cancer

Bone metastases represent severe complications associated with advanced-stage breast cancer, leading to skeletal-related events (SREs), such as pathological fractures, spinal cord compression, pain, and hypercalcemia, that severely impair quality of life and survival outcomes. Considering the clinical limitations of current systemic therapies, this thesis aimed to develop and assess an innovative strategy based on injectable nanomaterials with dual osteoinductive and targeted anticancer behaviors. The experimental approach was divided into in vitro and in vivo phases. In vitro studies evaluated the biological properties of graphene oxide (GO) and black phosphorus nanosheets (BPNs) and showed their high biocompatibility and potential to promote osteogenic differentiation in healthy osteoblasts (HOBs). Moreover, these nanomaterials exhibited selective cytotoxicity toward osteosarcoma cells (SAOS-2), especially when combined with photothermal stimulation using near-infrared (NIR) light. GO significantly enhanced alkaline phosphatase (ALP) expression in HOBs during the early stages, while simultaneously reducing proliferation and differentiation in tumor cells. BPNs further showed antioxidant capacity and promoted mineralization processes, reinforcing their suitability for bone tissue engineering applications. To validate the translational potential of these materials, an in vivo model of bone metastasis was performed. To induce the formation of bone metastases, the animals were subjected to an injection into the tibia with 105 cells (MDA-BO2 stably transfected with luciferase). This procedure was performed on all experimental groups (T0). The successful injection of localized metastasis was confirmed through bioluminescence imaging and micro-CT analysis. After tumor cell inoculation, mice were monitored by bioluminescence at T7 and T21. At T21, the animals were randomized to a treatment group and treated directly in the bone lesion. The effect was analyzed in terms of reduction of skeletal tumor load and osteolytic lesions. Post-mortem examinations revealed no distant organ metastases. While definitive histopathological and microtomographic analyses are still ongoing, preliminary results are promising. They suggest that localized delivery of GO and BPNs may reduce tumor burden while promoting bone repair, offering a potential non-invasive alternative for the treatment of metastatic bone lesions. This study lays the groundwork for future translational research aimed at developing multifunctional biomaterials for integrated oncologic and orthopedic care.