A lipidic mesophase with tunable release properties for the local delivery of macromolecules: the apoferritin nanocage, a case study

Lipid mesophases are able to incorporate and release a plethora of molecules, spanning from hydrophobic drugs to small hydrophilic proteins and therefore they have been widely used as drug delivery systems. However, their 3–5 nm water channels do not allow the release of large hydrophilic molecules such as monoclonal antibodies and therapeutic proteins. To overcome this major geometrical constraint, we designed a gel by mixing monoacylglycerol lipids, generally recognized as safe for human and/or animal use by FDA, and phospholipids, to obtain a material with swollen water channels suitable to host and further release macromolecules. Apoferritin, a 12 nm nanocage protein with intrinsic tumor-targeting properties able to incorporate several molecules, was selected here as the hydrophilic model protein to be embedded in the biocompatible gel. When immersed completely in the release media, mesophases with a swollen water channel of 22 nm, composed of monoolein and doped with 5 mole% of DOPS and 10 mole% of Chol allowed us to achieve a protein release of 60%, which is 120 times higher with respect to that obtained by employing non swollen-LMPs composed only of monoolein. Thus, the formulation can be administered locally to the rectal or vaginal mucosa, reducing the drawbacks often associated with the parenteral administration of bio-therapeutics. This approach would pave the way for the local application of other biomacromolecules (including human ferritin, monoclonal antibodies and antibody drug-conjugates) in those diseases easily reachable by a local application such as rectal or vaginal cancer.

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About this article: A lipidic mesophase with tunable release properties for the local delivery of macromolecules: the apoferritin nanocage, a case study O. Elzenaty, P. Luciani and S. Aleandri, J. Mater. Chem. B, 2022, Advance Article , DOI: 10.1039/D2TB00403H

Materials
Dimodan MO 90D was gifted by Danisco (Denmark) and was used as received. This commercial-grade form contains more than 90 wt% monoolein (MO). 1,2-Dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (DOPG) and 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) was kindly provided by LIPOID (Ludwigshafen, Germany). 2-Dioleoyl-3-trimethylammonium propane (DOTAP) was purchased from Merck (Darmstadt, Germany). Apoferritin (ApoF) was purchased from MP Biomedicals (Irvine, CA USA). Cholesterol (Chol; Grade ≥ 99%) and PBS tablets (one tablet in 1 L of deionized H2O yields 140 mM NaCl, 10 mM phosphate buffer, and 3 mM KCl, pH 7.4 at 25 °C.) were purchased by Sigma Aldrich. Ultrapure water of resistivity 18.2 MΩ.cm was produced by Barnstead Smart2pure (Thermo Scientific) and used as the aqueous phase. Chloroform was obtained from Fisher Scientific (Schwerte, Germany).

Conclusions
Using phospholipids to enlarge the water channels of bicontinuous cubic phases and Chol which keeps stable the fluid bilayer, we created swollen gels able to host and release the embedded ApoF. This safe and easy-to-manufacture release system could serve as a versatile platform to encapsulate biomacromolecules and it paves the way for the mucosal application of ApoF and other biomacromolecules including HFt, mAb and antibody–drug conjugates in diseases such as rectal and vaginal tumors, that are easily reachable by local administration, reducing the systemic drawbacks associated with a parenteral administration.
The use of such a gel could allow the patient to apply the formulation similarly to an enema or a vaginal irrigation; yet, differently from pharmaceutical solutions, the viscous gel could initiate a sustained local protein release decreasing dosing frequency and improving patient compliance.

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