Sustained-release G-CSF microspheres using a novel solid-in-oil-in-oil-in-water emulsion method

Abstract

Background

The main treatments for cancers are still chemotherapy and radiotherapy for intermediate-stage cancer and terminal cancer. However, the therapeutic methods often result in a decreased neutrophilic granulocyte count and other side effects. In this study, in order to improve the neutrophilic granulocyte levels in the blood after radiotherapy and chemotherapy, we developed a sustained-release granulocyte colony–stimulating factor (G-CSF) microsphere formulation using a novel solid-in-oil-in-oil-in-water (S/O/O/W) emulsification method.

Methods

G-CSF was loaded into dextran nanoparticles by freezing-induced phase separation, and then the G-CSF–loaded nanoparticles were encapsulated into sustained-release poly(lactic-co- glycolic acid) microspheres using S/O/O/W emulsification. The control microspheres were also prepared through W/O/W emulsification. The performance of the two microsphere formulations was investigated both in vitro and in vivo.

Results

The microspheres for the controlled release of G-CSF in a zero-order or near-zero-order pattern were provided for 2 weeks. The in vitro cumulative G-CSF release kept over 90% of its bioactivity, which was proved by a NFS-60 cell line growth assay. The microspheres of the control group fabricated by W/O/W emulsification maintained less then half of its bioactivity. The in vivo efficacy of microspheres made using the S/O/O/W method was higher than those using the W/O/W method.

Conclusion

These results suggested that the microspheres prepared by the S/O/O/W method had increased neutrophil activity compared to those prepared by W/O/W.

Keywords:

• microspheres
• bioactivity
• G-CSF
• stability
• sustained release

Acknowledgments

The authors are grateful to the National Natural Science Foundation of China (nos 81170292 and 81100223) and the PhD Programs Foundation of the Ministry of Education of China (no 20090073120085) for financial support. We are also grateful for the generous support from the Instrumental Analysis Centre (IAC) of Shanghai Jiao Tong University.

Disclosure

The authors declare no competing financial interests in this work.