A new study describes an engineered microscopic robot that may offer a more effective way to treat nonmuscle-invasive bladder cancer, a form of the disease known for its high recurrence rate. Current treatments are often limited by a dense extracellular matrix that blocks drug penetration and by a lack of tumor-specific targeting. The newly reported system combines living bacteria with synthetic nanoparticles and a cancer drug to overcome these barriers.
The platform, called HH-B-DM4-NT, starts with a bacterium named Hathewaya histolytica, which naturally secretes an enzyme that degrades collagen. The researchers coated this bacterium with bismuth ferrite nanoparticles, attached a microtubule inhibitor called DM4, and added a targeting ligand known as neurotensin. This ligand helps the system recognize bladder cancer cells that overexpress the NTS1 receptor.
When delivered directly into the bladder, the bacteria begin breaking down collagen in the tumor’s surrounding matrix. This loosens the dense tissue and allows the chemotherapy drug DM4 to penetrate more deeply. The drug then disrupts intercellular networks within the tumor. At the same time, ultrasound is applied from outside the body. The bismuth ferrite nanoparticles respond to ultrasound by generating reactive oxygen species, which cause further damage to cancer cells and trigger a form of cell death that can alert the immune system.
In laboratory tests, the system produced collagen degradation, disrupted three-dimensional tumor spheroids, and killed 90.8 percent of cancer cells. Further analysis showed that the treatment caused mitochondrial dysfunction, DNA damage and apoptosis. It also stimulated dendritic cell maturation and shifted macrophages toward the M1, or pro-inflammatory, phenotype. These immune changes are considered important for long-term antitumor responses.
In an orthotopic mouse model of bladder cancer, the combined treatment achieved 82.4 percent tumor inhibition and significantly prolonged survival compared with control groups. The treated tumors also showed increased infiltration of CD8 positive T cells and a favorable shift in the M1 to M2 macrophage ratio, indicating that the local therapy helped remodel the immunosuppressive tumor microenvironment.
The authors note that the system integrates several functions into one platform: tumor targeting, extracellular matrix disruption, immune activation and physical clearance of tumor debris through urine. While the results are promising, they emphasize that additional studies are needed to evaluate safety and long-term efficacy.
This research, titled “Active bacteria-delivered nanosystems for multimodal bladder cancer therapy” was supported by a grant from the Beijing-Tianjin-Hebei Natural Science Foundation Cooperation Project and National Natural Science Foundation of China.
Science Bulletin