Objectives: Currently, the most important treatment approach for hemophilia type A is recombinant Factor VIII. However, due to its low retention time in the blood, the patients usually need successive injections. In addition, neutralization of injected proteins by antibodies complicates treatment. We examined the prolongation of the persistence time of injectable FVIII in the blood and the potential effects on survival using promising PEGylated liposomes (PEGLip) utilizing hydrogenated soy phosphatidylcholine (HSPC, Tm= 54.5 ºC) and 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC, Tm= - 2 ºC).
Materials and methods: Nanoliposomes with different percentages of PEG (3% and 5%) were obtained via the thin film hydration procedure and extrusion. Liposomal FVIII formulation was prepared and characterization was done.
Results: The results revealed that the formulations are in the 80-120 nm range with uniform dispersion, which was confirmed using transmission electron microscopy (TEM) imaging. The phase transition temperature (Tm) of the liposomes was obtained by differential scanning calorimetry (DSC). With an attachment efficacy of approximately 87%, proteins bind non-covalently yet with a strong affinity to the exterior of PEGLip. The final formulations underwent additional examination. No significant change was observed in size, charge, and PDI between the FVIII-conjugated liposomal formulations and their liposomal nanoparticles. The selected formulations were injected into BALB/c mice. The circulation time and potential clotting effectiveness of PEGLip-FVIII are vastly improved over free protein, in non-hemophilic mice.
Conclusion: The obtained results showed that using phospholipids with high Tm (HSPC) can improve the hemostatic efficiency of liposomes more than phospholipids with low Tm (POPC).
Keywords: Antihemophilic factor; Haemophilia therapy; Hemophilia A; PEGylated liposomes; Recombinant FVIII.