Precisely-controlled DNA-templated micelle as a multifunctional delivery platform for glioblastoma therapeutics

Abstract

Event Abstract Back to Event Precisely-controlled DNA-templated micelle as a multifunctional delivery platform for glioblastoma therapeutics Yeh-Hsing Lao1, Smruthi Suryaprakash1, Kyle K. Phua2 and Kam W. Leong1 1 Columbia University, Department of Biomedical Engineering, United States 2 National University of Singapore, Department of Chemical & Biomolecular Engineering, Singapore Introduction: For cancer therapy, single drug treatment may not be sufficient to completely eliminate all the cancer cells due to their heterogeneity and insensitivity against the induced inhibitory signals. How to deliver multiple anti-cancer drugs in a controlled manner is a challenge in the field. Here we design a precisely-controlled DNA-templated micelle that is able to deliver various types of anti-cancer drugs, such as chemodrugs and nucleic acids. The DNA template comprises a DNA bridge with an amine-bearing PEG segment (Fig 1A). The DNA bridge can be loaded with chemodrugs and nucleic acid payloads through intercalation and Watson-Crick base paring, respectively. On the other hand, the PEG segment provides a functional group for ligand conjugation. Payloads and ligands are preloaded before DNA micelle formation; the loading efficiency and ligand density are therefore controlled in this system. DNA templates undergo a nanoprecipitation to form micelles, and the formed DNA micelles are narrowly dispersed, colloidally stable, and with low toxicity. We evaluated this micelle in an application as glioblastoma (GBM) therapeutics: micelle/cell cluster for tumor targeting. Mesenchymal stem cell (MSC) clusters were decorated with the micelles to co-deliver two types of anti-cancer drugs. The micelle decoration did not influence the homing ability of MSC toward GBM cells, and the clusters showed faster migration toward GBM cells compared with individual MSC. Materials and Methods: PEGylated DNA templates were purified by reversed-phased HPLC using an acetonitrile/PBS mixture as an eluent. The template concentration was quantitated by UV-VIS spectroscopy. The therapeutic payloads were loaded onto the DNA templates through a gradient annealing process with a cooling rate of 1oC/min. Payload-carrying DNA micelles were formed via nanoprecipitation. To decorate the MSC cluster for micelle/cell delivery, we slightly modified the protocol published previously[1]. Briefly, DNA-templated micelles were 1:1 mixed with an alginate-containing MSC suspension, and the clusters were subsequently formed via a microfluidic technology. Results and Discussion: In this study we optimized the micelle formulation for simultaneous drug and nucleic acid loading. The size of this DNA-templated micelle was tunable and ranged from 15 to 150 nm with a narrow polydispersity (PDI < 0.1). Fig 1B shows an example of the smallest micelle in the series. Furthermore, this micelle was colloidally stable in serum-containing environment (Fig 1C). The loading efficiency could reach nearly 100 % (Fig 1D), and the efficacy could be also enhanced by optimizing the ligand density (Fig 1E). To enhance the therapeutic efficacy on GBM treatment, we have developed a micelle/MSC hybrid cluster for codelivering multiple anti-cancer drugs. MSCs hold tumor homing property as they express tumor-associated cytokine receptors[2]. MSCs in the cluster form showed higher migration toward GBM cells. For decorating MSC clusters, we found that more than 50% of micelles were loaded on the ECM of the cluster and not internalized by the MSCs (Fig 1F), and the MSC migration was not affected by the decoration (Fig 1G). Conclusion: A DNA-templated delivery system is specifically designed for GBM therapy. These micelles are size-tunable, colloidally stable, and relatively monodispersed and non-toxic. It shows the flexibility and capability to integrate with other anti-cancer approaches, thereby making a contribution toward improving the efficacy on treating GBM. YHL and SS acknowledge the fellowship support from Taiwanese Ministry of Education and Schlumberger Foundation, respectively. This work is supported by the Department of Defenses (W81XWH-12-1-0261 to KWL) and the Grant-In-Aid of Research Program from Sigma Xi Research Society (G20131015280632 to YHL).