Validation of the reconstituted high-density lipoprotein (rHDL) drug delivery platform using dilauryl fluorescein (DLF)

Abstract

Dilauryl fluorescein (DLF) is a lipid soluble molecule that becomes fluorescent when lauric acid is removed by hydrolysis The purpose of these studies was to evaluate DLF as a potential probe for the function of reconstituted high-density lipoproteins (rHDL) as hydrophobic drug transport vehicles. The DLF containing rHDL nanoparticles were characterized regarding their physical/chemical properties, including molecular diameter, molecular weight, chemical composition, and buoyant density. We investigated the uptake of DLF from rHDL in cells that overexpress the scavenger receptor (SR-B1), known to facilitate the selective cellular uptake of cholesteryl esters from HDL. These studies show that DLF can be incorporated into rHDL and redistributed in the plasma compartment. In addition, these studies demonstrated an enhanced uptake and hydrolysis of DLF from rHDL by cells that overexpress the SR-B1 receptor, suggesting the involvement of a receptor mediated mechanism. The incorporation of DLF into the rHDL nanoparticles appear to protect against hydrolysis in the systemic circulation based on the lower rate of rHDL/DLF hydrolysis compared with the free DLF during incubation with human plasma. DLF may thus be used as a probe to track the movement and metabolism of HDL core constituents, including cancer chemotherapeutic agents.

Enhanced solubility and functionality of valrubicin (AD-32) against cancer cells upon encapsulation into biocompatible nanoparticles

“…The rHDL/AD-32 nanoparticles, prepared by cholate dialysis, exhibited physico-chemical properties similar to that of native (circulating) human HDL10. 16 Overall, these particles exhibited similar shape, size, and chemical composition to formulations of rHDL/dilauryl fluorescein and rHDL/paclitaxel particles, described earlier. 13,15 The discrepancy in the size by DLS and other methods is likely to be due to the bias of the light scattering instrument toward larger particles.…”

“…21,34 Here, we report an attempt to overcome this solubility barrier by encapsulating the AD-32 in rHDL nanoparticles. [11][12][13][14][15][16] The advantageous characteristics of HDL-based drug carriers include small size, selective delivery via receptor targeting, stability during storage, and high payload capacity. [11][12][13][14][15][16] Encapsulation of lipophilic drugs within nanocarriers has shown great potential as an alternative or an adjunct to existing chemotherapy regimens.…”

“…[11][12][13][14][15][16] The advantageous characteristics of HDL-based drug carriers include small size, selective delivery via receptor targeting, stability during storage, and high payload capacity. [11][12][13][14][15][16] Encapsulation of lipophilic drugs within nanocarriers has shown great potential as an alternative or an adjunct to existing chemotherapy regimens. 4,5 In addition, the selective targeting of malignant cells through receptor-mediated uptake of anticancer drugs 13,14 is a key concept in mediating or eliminating the side effects of conventional chemotherapy.…”

“…[9][10][11] The rHDL nanoparticles have been identified as an effective drug-delivery system for highly lipophilic drugs the delivery of the drug to cancer cells and tumors occurs via a targeted, receptor-mediated mechanism involving the scavenger receptor class B type 1 (SR-B1). [13][14][15][16] The current study was undertaken to evaluate the in vitro therapeutic eff icacy of valrubicin [AD-32 (N-trifluoroacetyladriamycin-14-valerate)], a derivative of doxorubicin, which was originally developed as a cancer therapeutic agent, [17][18][19] leading to its restricted approval for treating Bacillus Calmette-Guerin (BCG)-resistant bladder cancers in 1998. 20,21 Even though AD-32 has been found to be much less toxic to normal tissues 16,22 than doxorubicin during preclinical studies, its therapeutic application has been confined to nonsystemic administration due to its poor water solubility.…”

“…[13][14][15][16] The current study was undertaken to evaluate the in vitro therapeutic eff icacy of valrubicin [AD-32 (N-trifluoroacetyladriamycin-14-valerate)], a derivative of doxorubicin, which was originally developed as a cancer therapeutic agent, [17][18][19] leading to its restricted approval for treating Bacillus Calmette-Guerin (BCG)-resistant bladder cancers in 1998. 20,21 Even though AD-32 has been found to be much less toxic to normal tissues 16,22 than doxorubicin during preclinical studies, its therapeutic application has been confined to nonsystemic administration due to its poor water solubility. This restriction remains in place except for recent attempts to extend the application of AD-32 to treat skin cancer and psoriasis via topical formulations.…”