Docetaxel-loaded solid lipid nanoparticles prevent tumor growth and lung metastasis of 4T1 murine mammary carcinoma cells

BACKGROUND

Metastasis causes the most breast cancer-related deaths in women. Here, we investigated the antitumor effect of solid lipid nanoparticles (SLN-DTX) when used in the treatment of metastatic breast tumors using 4T1-bearing BALB/c mice.

RESULTS

Solid lipid nanoparticles (SLNs) were produced using the high-energy method. Compritol 888 ATO was selected as the lipid matrix, and Pluronic F127 and Span 80 as the surfactants to stabilize nanoparticle dispersion. The particles had high stability for at least 120 days. The SLNs' dispersion size was 128 nm, their polydispersity index (PDI) was 0.2, and they showed a negative zeta potential. SLNs had high docetaxel (DTX) entrapment efficiency (86%), 2% of drug loading and showed a controlled drug-release profile. The half-maximal inhibitory concentration (IC₅₀) of SLN-DTX against 4T1 cells was more than 100 times lower than that of free DTX after 24 h treatment. In the cellular uptake test, SLN-DTX was taken into the cells significantly more than free DTX. The accumulation in the G2-M phase was significantly higher in cells treated with SLN-DTX (73.7%) than in cells treated with free DTX (23.0%), which induced subsequent apoptosis. TEM analysis revealed that SLN-DTX internalization is mediated by endocytosis, and fluorescence microscopy showed DTX induced microtubule damage. In vivo studies showed that SLN-DTX compared to free docetaxel exhibited higher antitumor efficacy by reducing tumor volume (p < 0.0001) and also prevented spontaneous lung metastasis in 4T1 tumor-bearing mice. Histological studies of lungs confirmed that treatment with SLN-DTX was able to prevent tumor. IL-6 serum levels, ki-67 and BCL-2 expression were analyzed and showed a remarkably strong reduction when used in a combined treatment.

CONCLUSIONS

These results indicate that DTX-loaded SLNs may be a promising carrier to treat breast cancer and in metastasis prevention.

Lipid nanoemulsion passive tumor accumulation dependence on tumor stage and anatomical location: a new mathematical model for in vivo imaging biodistribution studies

Nanoparticle delivery to tumor tissue is one of the most important applications of nanomedicine.

Monitoring circulating B cells in patients with multiple myeloma at diagnosis or in plateau phase: how prevalent is light chain isotype suppression?

Peripheral blood lymphocytes from 25 patients with multiple myeloma at diagnosis or in plateau phase, and from 18 healthy subjects, were analysed for the surface expression of CD19 and immunoglobulin (Ig) light chain isotypes by dual parameter flow cytometry. The aim was to test for the existence of light chain isotype suppression (LCIS). LCIS is a hypothetical suppressor mechanism which supposedly operates in myeloma patients with stable disease, causing a drop in the number of circulating B cells bearing the same Ig light chain isotype as the myeloma paraprotein. Our experiments emphasized that the use of a non-Ig, pan-B cell marker, combined with dual antigen analysis, is necessary to distinguish Ig on B cells form (cytophilic) Ig on some non-B cells. We found good correlation between results obtained using polyclonal versus monoclonal anti-light chain antibodies, and washed blood versus peripheral blood mononuclear cells. There was no evidence of an abnormal ratio of CD19+, K+ to CD19+, lambda + cells in any of the patients. Thus, these patients did not manifest LCIS, and these experiments raise doubts about the existence of this phenomenon. The results also illustrate the problem that may arise in the interpretation of one parameter flow cytometry.