Zahraa S. Al-Ahmady

Lipid-Peptide Vesicle Nanoscale Hybrids for Triggered Drug Release by Mild Hyperthermia in vitro and in vivo

The present study describes leucine zipper peptide-lipid hybrid nanoscale vesicles engineered by self-assembled anchoring of the amphiphilic peptide within the lipid bilayer. These hybrid vesicles aim to combine the advantages of traditional temperature-sensitive liposomes (TSL) with the dissociative, unfolding properties of a temperature-sensitive peptide to optimize drug release under mild hyperthermia, while improving in vivo drug retention. The secondary structure of the peptide and its thermal responsiveness after anchoring onto liposomes were studied with circular dichroism. In addition, the lipid-peptide vesicles (Lp-peptide) showed a reduction in bilayer fluidity at the inner core, as observed with DPH anisotropy studies, while the opposite effect was observed with an ANS probe, indicating peptide interactions with both the headgroup region and the hydrophobic core. A model drug molecule, doxorubicin, was successfully encapsulated in the Lp-peptide vesicles at higher than 90% efficiency following the remote loading, pH-gradient methodology. The release of doxorubicin from Lp-peptide hybrids in vitro indicated superior serum stability at physiological temperatures compared to lysolipid-containing temperature-sensitive liposomes (LTSL) without affecting the overall thermo-responsive nature of the vesicles at 42 °C. A similar stabilizing effect was observed in vivo after intravenous administration of the Lp-peptide vesicles by measuring (14)C-doxorubicin blood kinetics that also led to increased tumor accumulation after 24 h. We conclude that Lp-peptide hybrid vesicles present a promising new class of TSL that can offer previously unexplored opportunities for the development of clinically relevant mild hyperthermia-triggered therapeutic modalities.

Pharmacokinetics & tissue distribution of temperature-sensitive liposomal doxorubicin in tumor-bearing mice triggered with mild hyperthermia

Drug-loaded temperature-sensitive liposomes (TSL) in combination with hyperthermia (HT) have attracted considerable attention for cancer treatment. Different TSL systems have been designed with wide variations in their temperature sensitivity and drug release profile. Low temperature-sensitive liposomes (LTSL) with the capacity for ultrafast drug release, traditional temperature-sensitive (TTSL) with intermediate drug release properties and non-temperature-sensitive liposomes (NTSL) (no drug release) were dual-labeled with (3)H-cholesteryl hexadecyl ether ((3)H-CHE) lipid and loaded with (14)C-doxorubicin ((14)C-Dox). Their blood profile, serum stability, tissue distribution and tumor localization (B16F10 melanoma) were studied after intravenous administration and mild HT treatment. LTSL showed higher affinity for the liver compared to TTSL and NTSL which were uptaken mainly by spleen. Under normal conditions (no HT) Dox leakage from liposomes was expected, higher for LTSL, less for TTSL and minimal for NTSL. Localized HT did not affect the overall blood circulation or organ accumulation for all TSL studied. Since LTSL showed ultrafast Dox release kinetics at 42 °C, the highest drug accumulation in tumors was observed using this system immediately after HT, however decreased significantly after 24 h. In contrast, TTSL and NTSL showed 2-3 fold increase in both liposome and Dox levels that indicated enhanced tumor extravasation of intact Dox-loaded liposomes during the 60 min HT applications. More interestingly, high levels of drug tumor accumulation were achieved 24 h post-HT. This study offers further understanding on how the mechanisms of drug release from temperature-sensitive liposomes affect their pharmacological profile under mild hyperthermia.

Monoclonal antibody-targeted, temperature-sensitive liposomes: In vivo tumor chemotherapeutics in combination with mild hyperthermia.

The development of actively targeted, responsive delivery vectors holds great promise for cancer therapy. Here, we investigated whether enhanced therapeutic activity of temperature sensitive liposomes (TSL) could be obtained by mild hyperthermia-triggered release of the chemotherapeutic drug doxorubicin (DOX) after hCTMO1 monoclonal antibody (anti-MUC-1) binding and uptake into cancer cells. We showed that traditional TSL (TTSL) liposome systems maintained their physicochemical and thermal properties after conjugation to hCTMO1 full IgG. Receptor-mediated cellular uptake and cytotoxic efficacy of antibody-targeted TTSL (TTSL-Ab) were investigated using 2D and 3D cell culture models. Significant enhancement in cellular uptake and cytotoxic activity after 1h of heating at 42 °C was observed for TTSL-Ab compared to non-targeted liposomes in MUC-1 over-expressing breast cancer cells (MDA-MB-435). Tissue distribution and in vivo therapeutic activity were studied using different heating protocols to explore the effect of mild hyperthermia on the tumor accumulation of targeted TTSL and their therapeutic effect. Application of local, mild hyperthermia (42°C) significantly increased the tumor accumulation of targeted TSL compared to non-targeted liposomes, associated with a moderate improvement in therapeutic activity and survival.

Triggered doxorubicin release in solid tumors from thermosensitive liposome-peptide hybrids: Critical parameters and therapeutic efficacy.

Temperature‐sensitive vesicles designed by inclusion of leucine zipper peptides within a lipid bilayer (Lp‐Peptide hybrids) encapsulating Doxorubicin (DOX) have been reported. Intravenous administration of these constructs prolonged blood circulation kinetics and increased tumor accumulation in vivo with local mild hyperthermia. In this study, the biological activity of the DOX‐loaded Lp‐Peptide hybrid vesicles was further investigated at the cellular level and in vivo compared to lysolipid‐containing temperature‐sensitive liposomes (LTSL) and traditional temperature‐sensitive liposomes. Lp‐Peptide vesicles were not toxic to cell cultures at 37°C, while effective cancer cell toxicity was observed after 1 hr of heating at 42°C. The activity of Lp‐Peptide vesicles in vivo was studied using two different heating protocols to obtain tumor intravascular or interstitial drug release. Lp‐Peptide vesicle treatment allowing intravascular DOX release showed equally effective tumor growth retardation and survival to that of LTSL treatment. The Lp‐Peptide vesicles also offered therapeutic responses using the alternative heating protocol to maximise drug release within the tumor interstitium. Matching the drug release kinetics of temperature‐sensitive vesicles with the heating protocol applied is considered the most critical factor to determine therapeutic efficacy in the clinical translation of such modalities.

Engineering thermosensitive liposome-nanoparticle hybrids loaded with doxorubicin for heat-triggered drug release

The engineering of responsive multifunctional delivery systems that combine therapeutic and diagnostic (theranostic) capabilities holds great promise and interest. We describe the design of thermosensitive liposome-nanoparticle (NP) hybrids that can modulate drug release in response to external heating stimulus. These hybrid systems were successfully engineered by the incorporation of gold, silver, and iron oxide NPs into the lipid bilayer of lysolipid-containing thermosensitive liposomes (LTSL). Structural characterization of LTSL-NP hybrids using cryo-EM and AFM revealed the incorporation of metallic NPs into the lipid membranes without compromising doxorubicin loading and retention capability. The presence of metallic NPs in the lipid bilayer reinforced bilayer retention and offered a nanoparticle concentration-dependent modulation of drug release in response to external heating. In conclusion, LTSL-NP hybrids represent a promising versatile platform based on LTSL liposomes that could further utilize the properties of the embedded NPs for multifunctional theranostic applications.

Formation of protein corona in vivo affects drug release from temperature-sensitive liposomes

&NA; Thermally triggered drug release from temperature‐sensitive liposomes (TSL) holds great promise for cancer therapy. Different types of TSL have been designed recently for heat triggered drug release inside tumor blood vessels or after accumulation into the tumor interstitium. However, justification of drug release profiles is for far mainly based on in vitro release data. While these methods could be good enough to give early indication about the thermal sensitivity of TSL, they are still far from being optimum. This is because these methods do not take into consideration the actual adsorption of proteins onto the surface of TSL after their in vivo administration, also known as “protein corona” and the influence this could have on drug release. Therefore, in this study we compared thermal triggered drug release profile of two different types of doxorubicin encapsulated TSL; namely the lysolipid‐containing TSL (LTSL) and traditional TSL (TTSL) after their in vivo recovery from the blood circulation of CD‐1 mice. Ex vivo release profile at 42 °C was then tested either in the presence of full plasma or after removal of unbound plasma proteins (i.e. protein corona coated TSL). Our data showed that the influence of the environment on drug release profile was very much dependent on the type of TSL. LTSL release profile was consistently characterized by ultrafast drug release independent on the conditions tested. On the contrary, TTSL release profile changed significantly. Doxorubicin release from in vivo recovered TTSL was slow and incomplete in the presence of unbound plasma proteins, whereas very rapid drug release was detected from in vivo recovered and purified protein corona‐coated TTSL in the absence of unbound proteins. Using mass spectrometry and quantification of protein adsorption, we confirmed that this discrepancy is due to the changes in protein adsorption onto TTSL when heated in the presence of unbound proteins leading to reduction in drug release. In summary this study showed that the formation of the in vivo corona on TSL will have a dramatic impact on their release profile and is dependent on both their lipid composition and the protein content of the environment in which drug release is triggered. Graphical abstract Figure. No caption available. HighlightsWe investigated the effect of in vivo protein adsorption, also known as “protein corona”, onto the surface of TSL and its impact on their drug release profile. The formation of the in vivo corona on TSL liposomes has a dramatic impact on their release profile dependent on both TSL lipid composition and the protein content of the environment in which drug release is triggered. Our findings emphasize that the design of TSL for thermal triggered release cannot be truly predicted based on chemical composition and in vitro release studies only, since the biological environment in which drug release is occurring should be also critically considered.

Selective drug delivery approaches to lesioned brain through blood brain barrier disruption

ABSTRACT Introduction: The development of therapeutics for central nervous system (CNS) disorders is still considered a challenging area in drug development due to insufficient translocation through the blood-brain barrier (BBB). Under normal conditions, BBB restrict the penetration of more than 98% of blood-borne molecules including drugs to the CNS. However, recent research findings have proven that the nature of the BBB is altered in several neurological conditions. This complexity encourages revisiting drug delivery strategies to the CNS as this can give a wide range of opportunities for CNS drug development. Areas covered: This review focuses on nanotechnology-based drug delivery platforms designed for selective recruitment into the lesioned brain by taking advantages of BBB disruption that is associated with certain neurological conditions. Expert opinion: Current CNS therapeutic strategies do not fully address the pathophysiological adaptation of BBB in their design. The lack of selective delivery to the brain lesions has been the culprit behind the failure of many CNS therapeutics. This highlighted the need for smart designs of advanced drug delivery systems that take advantage of BBB structural changes in CNS diseases. Recently, promising examples have been reported in this area, however, more work is still required beyond the preclinical testing.