INNOVATIVE INJECTABLE LIPOSOME AND DRUG-IN-CYCLODEXTRIN-IN LIPOSOME SYSTEMS ENCAPSULATING ESTETROL FOR THE TREATMENT OF ISCHEMIA DISEASES IN PREMATURE BABIES

Purpose: In 2010, almost 15 million of babies in the world are prematurely borned, 11.1 % of the total amount of alive children. Despite the better neonatology techniques, the number of preterm babies with motor, vision, hearing or mental deficiencies is still constant along the last twenty years. Moreover, no efficacy treatment is available to the present day. The estetrol (E4) has an important role in the brain development and protection. The aim of this study is to develop new injectable liposome and drug-in-cyclodextrin-in-liposome (DCL) formulations, encapsulating E4 in order to enhance its crossing through the blood-brain barrier (BBB).
Methods: Hydroxypropyl-β-cyclodextrins (degrees of substitution 0.87 and 0.63) (HPβCD 0.87 and HPβCD 0.63) were used to increase E4 aqueous solubility. Liposome and DCL (E4-HPβCD 0.63 complex) formulations were prepared by thin-film hydration technique. The formulations were physicochemical characterized and stability in foetal bovine serum (FBS) was evaluated. LDH and MTS tests on endothelial, neuronal and BBB model cells were performed in vitro on the liposome formulation. Hemocompatibility of the formulations was evaluated on red blood cells, platelet aggregation and coagulation. BBB passage tests were performed using human BBB cell line (hCMEC/D3).
Results: E4-HPβCD complexes proportionally increased the solubility of the hormone. Due to the lower solubility obtained with HPβCD ds 0.87, only HPβCD ds 0.63 was retained for future tests. Liposomes and DCL encapsulating E4 were prepared. All the formulations had average particle size below 150 nm, polydispersity index below 0.10 and ζ potential around + 30 mV. The encapsulation efficacy for liposomes was between 3% and 10% while those of DCL are between 15% and 35%. Moreover, the formulations are capable to release 80 % (liposome) and 90 % (DCL) of encapsulated E4 after 3 h at 37°C. The formulations, incubated in FBS at 37°C under gentle stirring, keep the same size and do not form protein corona up to 6 h. The effect of liposome and DCL formulations on cell viability and integrity was evaluated. The results showed no toxic effects on all the tested cell lines. Hemocompatibility tests showed no hemolysis, platelet aggregation or effects on coagulation, confirming the possibility of the formulations to be intravenously administrated. Preliminary BBB passage tests highlighted the capability of the formulations to pass the BBB and reach the brain.
Conclusions: New non-toxic, hemocompatible liposome and DCL formulations encapsulating E4 were prepared. The formulations are promising drug delivery system to target estrogens to the brain, due to their physiochemical characteristics.
Aknowledgment : The authors thank Estetra SPRL for providing Estetrol.