Elucidating the structural organization of a novel low-density lipoprotein nanoparticle reconstituted with docosahexaenoic acid

Docosahexaenoic acid-loaded nanoparticles: A state-of-the-art of preparation methods, characterization, functionality, and therapeutic applications

Docosahexaenoic acid (DHA, C22:6 n-3), an omega-3 polyunsaturated fatty acid, offers several beneficial effects. DHA helps in reducing depression, autoimmune diseases, rheumatoid arthritis, attention deficit hyperactivity syndrome, and cardiovascular diseases. It can stimulate the development of brain and nerve, alleviate lipids metabolism-related disorders, and enhance vision development. However, DHA susceptibility to chemical oxidation, poor water solubility, and unpleasant order could restrict its applications for nutritional and therapeutic purposes. To avoid these drawbacks and enhance its bioavailability, DHA can be encapsulated using an effective delivery system. Several encapsulation methods are recognized, and DHA-loaded nanoparticles have demonstrated numerous benefits. In clinical studies, positive influences on the development of several diseases have been reported, but some assumptions are conflicting and need more exploration, since DHA has a systemic and not a targeted release at the required level. This might cause the applications of nanoparticles that could allow DHA release at the required level and improve its efficiency, thus resulting in a better controlling of several diseases. In the current review, we focused on researches investigating the formulation and development of DHA-loaded nanoparticles using different delivery systems, including low-density lipoprotein, zinc oxide, silver, zein, and resveratrol-stearate. Silver-DHA nanoparticles presented a typical particle size of 24 nm with an incorporation level of 97.67 %, while the entrapment efficiency of zinc oxide-DHA nanoparticles represented 87.3 %. By using zein/Poly (lactic-co-glycolic acid) stabilized nanoparticles, DHA's encapsulation level reached 84.6 %. We have also highlighted the characteristics, functionality and medical implementation of these nanoparticles in the treatment of inflammations, brain disorders, diabetes as well as hepatocellular carcinoma.

Repeated trans-arterial treatments of LDL-DHA nanoparticles induce multiple pathways of tumor cell death in hepatocellular carcinoma bearing rats

Introduction

Repeated hepatic arterial delivery of therapeutic agents to the liver by percutaneously implanted port-catheter systems has been widely used to treat unresectable liver cancer. This approach is applied to assess the therapeutic efficacy of repeated low-density lipoprotein-docosahexaenoic acid (LDL-DHA) nanoparticle treatments in a rat model of hepatocellular carcinoma.

Methods

N1S1 hepatoma bearing rats underwent placement of a percutaneously implanted hepatic artery port-catheter system and were allocated to untreated, control LDL-triolein (LDL-TO) or LDL-DHA nanoparticle infusions groups. Treatments were performed every three days over a nine day study period. MRI was performed at baseline and throughout the study. At the end of the study tissue samples were collected for analyses.

Results and Discussion

Implantation of the port catheters was successful in all rats. MRI showed that repeated infusions of LDL-DHA nanoparticles significantly impaired the growth of the rat hepatomas eventually leading to tumor regression. The tumors in the LDL-TO treated group showed delayed growth, while the untreated tumors grew steadily throughout the study. Histopathology and MRI support these findings demonstrating extensive tumor necrosis in LDL-DHA treated groups while the control groups displayed minor necrosis. Molecular and biochemical analyses also revealed that LDL-DHA treated tumors had increased levels of nuclear factor-kappa B and lipid peroxidation and depletion of glutathione peroxidase 4 relative to the control groups. Evidence of both ferroptosis and apoptosis tumor cell death was observed following LDL-DHA treatments. In conclusion repeated transarterial infusions of LDL-DHA nanoparticles provides sustained repression of tumor growth in a rat hepatoma model.

Docosahexaenoic Acid Delivery Systems, Bioavailability, Functionality, and Applications: A Review

Docosahexaenoic acid (DHA), mainly found in microalgae and fish oil, is crucial for the growth and development of visual, neurological, and brain. In addition, DHA has been found to improve metabolic disorders associated with obesity and has anti-inflammatory, anti-obesity, and anti-adipogenesis effects. However, DHA applications in food are often limited due to its low water solubility, instability, and poor bioavailability. Therefore, delivery systems have been developed to enhance the remainder of DHA activity and increase DHA homeostasis and bioavailability. This review focused on the different DHA delivery systems and the in vitro and in vivo digestive characteristics. The research progress on cardiovascular diseases, diabetes, visual, neurological/brain, anti-obesity, anti-inflammatory, food applications, future trends, and the development potential of DHA delivery systems were also reviewed. DHA delivery systems could overcome the instability of DHA in gastrointestinal digestion, improve the bioavailability of DHA, and better play the role of its functionality.

Membrane therapy using DHA suppresses epidermal growth factor receptor signaling by disrupting nanocluster formation

Epidermal growth factor receptor (EGFR) signaling drives the formation of many types of cancer, including colon cancer. Docosahexaenoic acid (DHA, 22∶6Δ4,7,10,13,16,19), a chemoprotective long-chain n-3 polyunsaturated fatty acid suppresses EGFR signaling. However, the mechanism underlying this phenotype remains unclear. Therefore, we used super-resolution microscopy techniques to investigate the mechanistic link between EGFR function and DHA-induced alterations to plasma membrane nanodomains. Using isogenic in vitro (YAMC and IMCE mouse colonic cell lines) and in vivo (Drosophila, wild type and Fat-1 mice) models, cellular DHA enrichment via therapeutic nanoparticle delivery, endogenous synthesis, or dietary supplementation reduced EGFR-mediated cell proliferation and downstream Ras/ERK signaling. Phospholipid incorporation of DHA reduced membrane rigidity and the size of EGFR nanoclusters. Similarly, pharmacological reduction of plasma membrane phosphatidic acid (PA), phosphatidylinositol-4,5-bisphosphate (PIP2) or cholesterol was associated with a decrease in EGFR nanocluster size. Furthermore, in DHA-treated cells only the addition of cholesterol, unlike PA or PIP2, restored EGFR nanoscale clustering. These findings reveal that DHA reduces EGFR signaling in part by reshaping EGFR proteolipid nanodomains, supporting the feasibility of using membrane therapy, i.e., dietary/drug-related strategies to target plasma membrane organization, to reduce EGFR signaling and cancer risk.

An implanted port-catheter system for repeated hepatic arterial infusion of low-density lipoprotein-docosahexaenoic acid nanoparticles in normal rats: A safety study

BACKGROUND

In recent years, small animal arterial port-catheter systems have been implemented in rodents with reasonable success. The aim of the current study is to employ the small animal port-catheter system to evaluate the safety of multiple hepatic-artery infusions (HAI) of low-density lipoprotein-docosahexaenoic acid (LDL-DHA) nanoparticles to the rat liver.

METHODS

Wistar rats underwent surgical placement of indwelling HAI ports. Repeated administrations of PBS or LDL-DHA nanoparticles were performed through the port at baseline and days 3 and 6. Rats were sacrificed on day 9 at which point blood and various organs were collected for histopathology and biochemical analyses.

RESULTS

The port-catheter systems were implanted successfully and repeated infusions of PBS or LDL-DHA nanoparticles were tolerated well by all animals over the duration of the study. Measurements of serum liver/renal function tests, glucose and lipid levels did not differ between control and LDL-DHA treated rats. The liver histology was unremarkable in the LDL-DHA treated rats and the expression of hepatic inflammatory regulators (NF-κβ, IL-6 and CRP) were similar to control rats. Repeated infusions of LDL-DHA nanoparticles did not alter liver glutathione content or the lipid profile in the treated rats. The DHA extracted by the liver was preferentially metabolized to the anti-inflammatory DHA-derived mediator, protectin DX.

CONCLUSION

Our findings indicate that repeated HAI of LDL-DHA nanoparticles is not only well tolerated and safe in the rat, but may also be protective to the liver.