Modular nanotransporters: a multipurpose in vivo working platform for targeted drug delivery

Tatiana A Slastnikova^1,2, Andrey A Rosenkranz^1,2, Pavel V Gulak¹, Raymond M Schiffelers³, Tatiana N Lupanova^1,4, Yuri V Khramtsov¹, Michael R Zalutsky⁵, Alexander S Sobolev^1,2
1Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Moscow, Russia; ²Department of Biophysics, Biological Faculty, Moscow State University, Vorobyevy Gory, Moscow, Russia; ³Laboratory for Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, the Netherlands; ⁴Department of Bioengineering, Biological Faculty, Moscow State University, Vorobyevy Gory, Moscow, Russia; ⁵Department of Radiology, Duke University Medical Center, Durham, NC, USA

Background: Modular nanotransporters (MNT) are recombinant multifunctional polypeptides created to exploit a cascade of cellular processes, initiated with membrane receptor recognition to deliver selective short-range and highly cytotoxic therapeutics to the cell nucleus. This research was designed for in vivo concept testing for this drug delivery platform using two modular nanotransporters, one targeted to the α-melanocyte-stimulating hormone (αMSH) receptor overexpressed on melanoma cells and the other to the epidermal growth factor (EGF) receptor overexpressed on several cancers, including glioblastoma, and head-and-neck and breast carcinoma cells.
Methods: In vivo targeting of the modular nanotransporter was determined by immunofluorescence confocal laser scanning microscopy and by accumulation of ¹²⁵I-labeled modular nanotransporters. The in vivo therapeutic effects of the modular nanotransporters were assessed by photodynamic therapy studies, given that the cytotoxicity of photosensitizers is critically dependent on their delivery to the cell nucleus.
Results: Immunohistochemical analyses of tumor and neighboring normal tissues of mice injected with multifunctional nanotransporters demonstrated preferential uptake in tumor tissue, particularly in cell nuclei. With ¹²⁵I-labeled MNT{αMSH}, optimal tumor:muscle and tumor:skin ratios of 8:1 and 9.8:1, respectively, were observed 3 hours after injection in B16-F1 melanoma-bearing mice. Treatment with bacteriochlorin p-MNT{αMSH} yielded 89%–98% tumor growth inhibition and a two-fold increase in survival for mice with B16-F1 and Cloudman S91 melanomas. Likewise, treatment of A431 human epidermoid carcinoma-bearing mice with chlorin e₆- MNT{EGF} resulted in 94% tumor growth inhibition compared with free chlorin e₆, with 75% of animals surviving at 3 months compared with 0% and 20% for untreated and free chlorin e6-treated groups, respectively.
Conclusion: The multifunctional nanotransporter approach provides a new in vivo functional platform for drug development that could, in principle, be applicable to any combination of cell surface receptor and agent (photosensitizers, oligonucleotides, radionuclides) requiring nuclear delivery to achieve maximum effectiveness.

Keywords: drug delivery, nanobiotechnology, nanomedicine, cancer therapy, photosensitizers, multifunctional nanotransporter