Release Of All-trans Retinoic Acid Research Articles

A microparticle delivery system for extended release of all-trans retinoic acid and its impact on macrophage insulin-like growth factor 1 release and myotube formation

Muscle atrophy secondary to disuse, aging, or illness increases the risk of injury, prolonged recovery, and permanent disability. The recovery process involves macrophages and their secretions, such as insulin-like growth factor 1 (IGF-1), which direct muscle to regenerate and grow. Retinoic acid receptor (RAR) activation in macrophages increases IGF-1 expression and can be achieved with all-trans retinoic acid (ATRA). However, poor bioavailability limits its clinical application. Thus, we encapsulated ATRA into poly(lactide-co-glycolide) microparticles (ATRA-PLG) to maintain bioactivity and achieve extended release. ATRA-PLG induces IGF-1 release by RAW 264.7 macrophages, and conditioned media from these cells enhances C2C12 myotube formation through IGF-1. Additionally, ATRA released from ATRA-PLG enhances myotube formation in the absence of macrophages. Toward clinical translation, we envision that ATRA-PLG will be injected in the vicinity of debilitated muscle where it can be taken up by macrophages and induce IGF-1 release over a predetermined therapeutic window. Along these lines, we demonstrate that ATRA-PLG microparticles are readily taken up by bone marrow-derived macrophages and reside within the cytosol for at least 12 days with no toxicity. Interestingly, ATRA-PLG induced IGF-1 secretion by thioglycolate-elicited macrophages, but not bone marrow derived macrophages. We found that the RAR isoforms present in lysate differed between the macrophages studied, which could explain the different IGF-1 responses to ATRA. Given that ATRA-PLG enhances myotube formation directly (through ATRA) and indirectly (through macrophage IGF-1) this study supports the further testing of this promising pharmaceutical using rodent models of muscle regeneration and growth.

Experimental design and characterization of dual-antibody-conjugated all-trans retinoic acid-loaded lipid nanoparticles as a potential cancer therapy

Antibody-targeted immunotherapy has emerged in cancer therapies regarding checkpoint inhibition with monoclonal antibodies, such as anti-programmed death-ligand 1 (anti-PD-L1) either given alone or in combination. However, when given alone, it may fail to activate tumor-specific T cells. The combinational therapy of anti-PD-L1 with anti-4-1BB and all-trans retinoic acid (ATRA) has come into prominence due to disease heterogeneity, resulting in the synergistic effects associated with greater T-cell responses. This study introduces anti-PD-L1 and anti-4-1BB-conjugated ATRA-loaded solid lipid nanoparticles (SLNs), where the Design-Expert Program was applied for the optimization. Accordingly, antibody–conjugated ATRA-loaded SLNs had uniform dispersions with mean diameters of 179.6 ± 12.6 nm. The formulations achieved the encapsulation efficiency (EE %) of ATRA at 21.2 ± 1.4 %, regarding the three-dimensional response surface graph. The binding efficiency of anti-4-1BB and anti-PD-L1 antibodies were determined as 85.59 ± 7.3 % and 90.02 ± 5.4 %, respectively. The release profile of formulations indicated the biphasic release of ATRA (ie., 76 ± 4.4 %) from SLNs within 24 h via the Higuchi model. Particle size distributions of SLNs displayed a 7 % increase (i.e., 190.5 ± 7.63 nm) at 4 °C over 2 months. The experimental design of anti-PD-L1- and anti-4-1BB-conjugated- ATRA-loaded SLNs highlighted the promising strategy for the development of alternative formulations and the potential approach for further cancer therapies.

Double-Layered Hollow Mesoporous Cuprous Oxide Nanoparticles for Double Drug Sequential Therapy of Tumors.

Cancer stem cells (CSCs) are one of the determinants of tumor heterogeneity and are characterized by self-renewal, high tumorigenicity, invasiveness, and resistance to various therapies. To overcome the resistance of traditional tumor therapies resulting from CSCs, a strategy of double drug sequential therapy (DDST) for CSC-enriched tumors is proposed in this study and is realized utilizing the developed double-layered hollow mesoporous cuprous oxide nanoparticles (DL-HMCONs). The high drug-loading contents of camptothecin (CPT) and all-trans retinoic acid (ATRA) demonstrate that the DL-HMCON can be used as a generic drug delivery system. ATRA and CPT can be sequentially loaded in and released from CPT3@ATRA3@DL-HMCON@HA. The DDST mechanisms of CPT3@ATRA3@DL-HMCON@HA for CSC-containing tumors are demonstrated as follows: 1) the first release of ATRA from the outer layer induces differentiation from CSCs with high drug resistance to non-CSCs with low drug resistance; 2) the second release of CPT from the inner layer causes apoptosis of non-CSCs; and 3) the third release of Cu+ from DL-HMCON itself triggers the Fenton-like reaction and glutathione depletion, resulting in ferroptosis of non-CSCs. This CPT3@ATRA3@DL-HMCON@HA is verified to possess high DDST efficacy for CSC-enriched tumors with high biosafety.

Immunomodulatory Microparticles Epigenetically Modulate T Cells and Systemically Ameliorate Autoimmune Arthritis.

Disease modifying antirheumatic drugs (DMARDs) have improved the prognosis of autoimmune inflammatory arthritides but a large fraction of patients display partial or nonresponsiveness to front-line DMARDs. Here, an immunoregulatory approach based on sustained joint-localized release of all-trans retinoic acid (ATRA), which modulates local immune activation and enhances disease-protective T cells and leads to systemic disease control is reported. ATRA imprints a unique chromatin landscape in T cells, which is associated with an enhancement in the differentiation of naïve T cells into anti-inflammatory regulatory T cells (Treg ) and suppression of Treg destabilization. Sustained release poly-(lactic-co-glycolic) acid (PLGA)-based biodegradable microparticles encapsulating ATRA (PLGA-ATRA MP) are retained in arthritic mouse joints after intra-articular (IA) injection. IA PLGA-ATRA MP enhance migratory Treg which in turn reduce inflammation and modify disease in injected and uninjected joints, a phenotype that is also reproduced by IA injection of Treg . PLGA-ATRA MP reduce proteoglycan loss and bone erosions in the SKG and collagen-induced arthritis mouse models of autoimmune arthritis. Strikingly, systemic disease modulation by PLGA-ATRA MP is not associated with generalized immune suppression. PLGA-ATRA MP have the potential to be developed as a disease modifying agent for autoimmune arthritis.

Integrated and dual-responsive lipopeptide nanovector with parallel effect to tumor and micro-environment regulation by efficient gene and drug co-delivery

The integrated lipopeptide (RVA)/gene complexes are fabricated with bi-directional regulation on tumor cells and micro-environment. After self-assembling and target coating modification, the poly(γ-glutamic acid) (γ-PGA)/RVA nano-vectors can sequentially respond to pH & redox stimuli, and guarantee efficient therapeutic gene delivery and control release of all-trans retinoic acid. The design provides a facile but promising strategy to treat refractory cancers.

A new application of surfactant-free microemulsion: Solubilization and transport of drugs and its transdermal release properties

BackgroundSurfactant-free microemulsion (SFME) has been used in the application of enzyme catalysis, material synthesis and raw material extraction but no research on nano drug carriers. MethodA novel green SFME with eucalyptus oil as the oil phase was developed as representative for solubilizing unstable and insoluble all-trans retinoic acid (ATRA), enhancing its stability and promoting its transdermal absorption. This work was investigated by experiment combined with simulation. Significant findingsATRA solubilization occurs in oil-in-water droplet of SFME and the dissolution process is spontaneous. The droplet sizes of ATRA-loaded SFMEs increase with the addition of ATRA. The solubility of ATRA is notably increased by SFME (10.08 × 103 μg·mL−1), 53,000 times higher than that in water and 504 times in silicone oil. Compared with previous studies, ATRA-loaded SFMEs have better light, thermal and centrifugal stability as well as oxidation resistance than ATRA-loaded silicone oil. All the droplet sizes of ATRA-loaded SFMEs are smaller than that reported, therefore, a better transdermal absorption effect is exhibited compared to ATRA-loaded azone. The transdermal release of ATRA is consistent with Korsmeyer-Peppas kinetic model. This research would be a pioneer in the new application field of SFME.

Fabrication of All-Trans Retinoic Acid loaded Chitosan/Tripolyphosphate Lipid Hybrid Nanoparticles as a Novel Oral Delivery Approach for Management of Diabetic Nephropathy in Rats.

The present study aims to formulate all-trans retinoic acid (ATRA) loaded chitosan/tripolyphosphate lipid hybrid nanoparticles (CTLHNs) for enhancing its solubility and oral delivery. This is to improve ATRA therapeutic effect on diabetic nephropathy (DN). CTLHNs were prepared by o/w homogenization, employing stearic acid, to form lipid nanoparticles coated with chitosan that is stabilized against acidic pH via sodium tripolyphosphate crosslinking. Chitosan coated (F7) and naked lipid nanoparticles (F6) were also prepared for comparison with CTLHNs. In vitro characterization for the prepared formulations was performed comprising entrapment efficiency, particle size, zeta potential, transmission electron microscopy, FT-IR spectroscopy and x-ray diffraction. Stability of chitosan coat in GI fluid revealed that CTLHNs were more stable than F7. In vitro release indicated an enhanced release of ATRA from the developed formulations. In vitro mucoadhesion study proved a notable mucoadhesive property for CTLHNs. In DN rat model, serum levels of creatinine and urea were elevated, over expression of tumor necrosis factor alpha (TNF-α), granulocyte macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF) and intercellular adhesion molecule-1 (ICAM-1) were observed. In addition, adenosine monophosphate activated protein kinase (AMPK) and liver kinase B1 (LKB1) expressions were decreased in DN rats. Treatment with free ATRA and the selected formulations led to a significant amelioration of DN by reducing of creatinine, urea, TNF-α, ICAM-1, GM-CSF, VEGF levels as well as elevating AMPK and LKB1 levels. The order of activity was: CTLHNs > F7 > F6 > free ATRA, as proved by histopathological examination.

Co-delivery of all-trans-retinoic acid and docetaxel in drug conjugated polymeric nanoparticles: Improving controlled release and anticancer effect

Nanoparticular combination chemotherapy with polymer-drug graft has been designed to overcome the limitations of traditional chemotherapy. In this purpose, all-trans retinoic acid (ATRA) grafted poly β-amino ester (ATRA-g-PBAE copolymer) was applied to encapsulate docetaxel (DTX) by the solvent displacement method and to make DTX loaded ATRA-g-PBAE nanoparticles (NPs). The size of NPs was optimized using response surface methodology (RSM). The size and zeta potential of NPs were measured by Zetasizer, and the morphology was evaluated by transmission electron microscopy (TEM). In vitro release was performed at pH 7.4 and 5.8. The anti-angiogenic effect, cytotoxicity, and blood compatibility of DTX loaded ATRA-g-PBAE NPs were investigated. The optimum size of the NPs was 137.9 ± 2.09 nm. The in vitro release of ATRA and DTX from NPs was pH-dependent, and it accelerated as pH decreased from 7.4–5.8. Results demonstrated that NPs had higher cytotoxicity and anti-angiogenic activity than that of free ATRA and DTX. In conclusion, biocompatible ATRA-g-PBAE NPs are a promising controlled released system for co-delivery of ATRA and DTX in chemotherapy.

Sustained Release of All-trans Retinoic Acid from Chitosan-coated Poly(DL-lactide-co-glycolide) Nanoparticles

Sustained Release of All-trans Retinoic Acid from Chitosan-coated Poly(DL-lactide-co-glycolide) Nanoparticles

PD-l1 conjugated all-trans retinoic acid nanoparticles for targeted treatment of oral dysplasia and oral squamous cell carcinoma

Objectives The present study conjugated all-trans retinoic acid (ATRA) with poly(lactic acid-co-glycolic acid)-block-poly(ethylene glycol) (PLGA-PEG) nanocarriers, and combined with anti–programmed death-ligand 1 (PD-L1) antibody to achieve targeted therapy for oral squamous cell carcinoma (OSCC) and oral dysplasia. Study Design The molecular mechanism of ATRA and PD-L1 was studied by using Cell Counting Kit-8 (CCK8), flow cytometry, Western blot, and immunohistochemistry. The effect of ATRA on OSCC and oral dysplasia cell proliferation inhibition, apoptosis induction, and PD-L1 downregulation was significantly enhanced after signal transducer and activator of transcription 3 (STAT3) signaling blockade. PD-L1 was highly expressed in patients with oral leukoplakia and OSCC compared with normal controls. By the measurement of dynamic light scattering, the average particle size and zeta potential of ATRA–PLGA–PEG and ATRA–PLGA-PEG–PD-L1 was 97 nm and –3.6 mV, 105 nm and –5.7 mV, respectively. The release of ATRA in nanoparticles reached 55% within 36 hours. The maximum encapsulation efficiency and loading capacity of ATRA into the nanoparticles reached 76.29% and 12.18%, respectively. The PEG-PLGA nanocarrier had almost no cytotoxicity, and the nanomedicine significantly inhibited cell proliferation of DOK and CAL27 cells on the in vitro cytotoxicity test. After 1 hour of incubation, the Nile red group showed few fluorescence intensity, whereas the 2 nanoparticle groups were readily detectable under confocal microscopy. Moreover, nanoparticles enhanced anticancer activity and reduced side effects compared with free ATRA in C3 H tumor-bearing mice. Furthermore, ATRA–PLGA-PEG–PD-L1 nanoparticles could target the tumor more effectively compared with the control group, as shown by whole-animal fluorescence imaging. Multicolor immunohistochemistry revealed effective regulation of expression of the related proteins after nanoparticle treatment. Results The mechanism of ATRA and PD-L1 downregulation was closely associated with STAT3 signaling inhibition in both OSCC and oral dysplasia. PD-L1, which was highly expressed in human oral leukoplakia and OSCC tissues, proved to be a specific target site for cancer therapy. The ATRA–PLGA-PEG–PD-L1 nanoparticles had lower toxicity and higher biocompatibility and targeted the tumor more specifically compare with free ATRA, both in vitro and in vivo. Conclusions These findings suggested that ATRA induced antitumor effects via STAT3 signaling inhibition in oral dysplasia and OSCC. The use of ATRA–PLGA-PEG–PD-L1 nanomedicine was an effective and nontoxic targeted therapy for oral dysplasia and OSCC, both in vitro and in vivo.

All-trans retinoic acid eluting poly(diol citrate) wafers for treatment of glioblastoma.

Current treatments for glioblastoma have failed to significantly increase patient survival, are extremely cytotoxic, can cause severe side effects, and are ineffective. Given these limitations, drugs other than cytotoxic chemotherapeutic agents are being explored. Recent studies show that all-trans retinoic acid (ATRA) could be effective on cancer cells as they have been shown to suppress carcinogenesis in a variety of tumor types and can reverse premalignant lesions and inhibit the development of secondary tumors in the head and neck of cancer patients. However, the therapeutic effects of retinoids such as ATRA are undermined by its rapid in vivo metabolism by cytochrome P450 enzymes, difficulty in crossing the blood-brain barrier, and sensitivity to isomerization/degradation. To overcome these limitations, we have developed a porous poly(1,8-octanediol-co-citrate; POC) wafer that stabilizes all-trans retinoic acid, while slowly releasing ATRA over 3 months. Release of ATRA from POC wafers inhibited proliferation of U87MG (glioblastoma) cells and caused upregulation in genes associated with differentiation into normal phenotype and apoptosis. Therefore, ATRA eluting poly(diol citrate) wafers are a promising treatment option compared to traditional cytotoxic chemotherapeutic agents.

A 3D bioprinted hydrogel mesh loaded with all-trans retinoic acid for treatment of glioblastoma

Treatment of glioblastoma (GBM), as the most lethal type of brain tumor, still remains a major challenge despite the various therapeutic approaches developed over the recent decades. GBM is considered as one of the most therapy-resistant human tumors. Treatment with temozolomide (TMZ) chemotherapy and radiotherapy in GBM patients has led to 30% of two-year survival rate (American Brain Tumor Association), representing a demanding field to develop more effective therapeutic strategies. This study presents a novel method for local delivery of all-trans retinoic acid (ATRA) for targeting GBM cells as a possible adjuvant therapeutic strategy for this disease. We have used 3D bioprinting to fabricate hydrogel meshes laden with ATRA-loaded polymeric particles. The ATRA-loaded meshes have been shown to facilitate a sustained release of ATRA with tunable release rate. Cell viability assay was used to demonstrate the ability of fabricated meshes in reducing cell growth in U-87 MG cell line. We later showed that the developed meshes induced apoptotic cell death in U-87 MG. Furthermore, the use of hydrogel for embedding the ATRA-loaded particles can facilitate the immobilization of the drug next to the tumor site. Our current innovative approach has shown the potential to open up new avenues for treatment of GBM, benefiting patients who suffer from this debilitating disease.

Lipid-polymer nanoparticles with CD133 aptamers for targeted delivery of all-trans retinoic acid to osteosarcoma initiating cells

Osteosarcoma, a common type of bone cancer in children, and represents an aggressive and fetal cancer worldwide. Osteosarcoma initiating cells are considered to be a subpopulation of cancer cells which contribute to the progression, recurrence, metastasis and multi-drug resistance of osteosarcoma. CD133 is considered to be one marker for osteosarcoma initiating cells. All-trans retinoic acid (ATRA), an active metabolite of vitamin A under the family retinoid, is an up-and-coming drug which was able to effectively treat various cancer initiating cells. Nevertheless, there have been no research that reported the activity of ATRA against osteosarcoma initiating cells. In this research, we hereby examined the potential activity of ATRA in osteosarcoma initiating cells, and developed lipid-polymer nanoparticles with CD133 aptamers for targeted ATRA delivery to osteosarcoma initiating cells. Using the cytotoxicity assay, colony formation assay, tumorsphere formation assay and flow cytometry, the therapeutic effect of ATRA and ATRA-loaded lipid-polymer nanoparticles conjugated with CD133 aptamers (ATRA-PLNP-CD133) against osteosarcoma initiating cells were investigated. The results showed that ATRA exerted potent activity towards osteosarcoma initiating cells. ATRA-PLNP-CD133, which showed a size of 129.9 nm and a sustained release of ATRA during 144 h, was demonstrated to efficiently and specifically promote the ATRA delivery to osteosarcoma initiating cells, and achieve superior therapeutic efficacy in osteosarcoma compared with ATRA and non-targeted nanoparticles. This is the first report of the therapeutic efficacy of ATRA towards osteosarcoma initiating cells, and the increased ATRA delivery by nanoparticles to osteosarcoma initiating cells using CD133 aptamers. ATRA-PLNP-CD133 represent an up-and coming approach for the therapy of osteosarcoma initiating cells.

PH and redox dual-responsive copolymer micelles with surface charge reversal for co-delivery of all-trans-retinoic acid and paclitaxel for cancer combination chemotherapy.

BackgroundCo-delivery all-trans-retinoic acid (ATRA) and paclitaxel (PTX) is an effective strategy for cancer therapy. However, in many previous reported ATRA conjugated co-delivery systems, the ATRA was released slower than PTX, and the total drug release of ATRA far lower than that of PTX.PurposeWe designed and prepared a pH and redox dual responsive drug delivery system (DA-ss-NPs) co-delivery ATRA and PTX for cancer therapy. The surface charge of DA-ss-NPs could change from negative to positive under tumor slightly acidic microenvironment, and both drugs could be quickly released from DA-ss-NPs under intracellular high concentration of glutathione (GSH).MethodsThe DA-ss-NPs were constructed by encapsulating PTX into the hydrophobic core of the polymer micelles, in which the polymer was synthesized by conjugating ATRA and 2,3-Dimethylmalefic anhydride (DMA) on side chains of Cystamine dihydrochloride (Cys) modified PEG-b-PAsp (named DA-ss-NPs). The surface charge of DA-ss-NPs under different pH conditions were detected. And the drug release was also measured under different concentration of GSH. The therapeutic effect of DA-ss-NPs were investigated in Human lung cancer A549 cells and A549 tumor-bearing mice.ResultsThe zeta potential of DA-ss-NPs was -16.3 mV at pH 7.4, and which changed to 16 mV at pH 6.5. Cell uptake experiment showed that more DA-ss-NPs were internalized by A549 cells at pH 6.5 than that at pH 7.4. In addition, in presence of 10 mM GSH at pH 7.4, about 75%-85% ATRA was released from DA-ss-NPs within 48 h; but less than 20% ATRA was released without GSH. In vivo antitumor efficiency showed that the DA-ss-NPs could affectively inhibite the tumor in compared with control groups.ConclusionThe charge-reversal and GSH-responsive DA-ss-NPs provide an excellent platform for potential tumor therapy.

All-trans retinoic acid-encapsulated, CD20 antibody-conjugated poly(lactic-co-glycolic acid) nanoparticles effectively target and eliminate melanoma-initiating cells in vitro.

PurposeMelanoma, which is initiated from melanocytes, is the most fatal type of skin cancer. Melanoma-initiating cells significantly contribute to the initiation, metastasis, and recurrence of melanoma, and CD20 is a marker of melanoma-initiating cells. All-trans retinoic acid (ATRA) has been demonstrated to induce differentiation, inhibit proliferation, and promote the apoptosis of cancer cells and cancer-initiating cells (CICs). However, there has been no report on ATRA activity against melanoma-initiating cells. In this study, we examined the activity of ATRA against melanoma-initiating cells and developed ATRA-encapsulated poly(lactic-co-glycolic acid) (PLGA) nanoparticles, which were conjugated with a CD20 antibody (ATRA-PNP-CD20) for targeted delivery of ATRA to CD20+ melanoma-initiating cells.Materials and methodsThe effects of ATRA and ATRA-PNP-CD20 against melanoma-initiating cells were investigated using a cytotoxicity assay, tumorsphere formation assay, and flow cytometry.ResultsATRA-PNP-CD20 had a size of 126.9 nm and a negative zeta potential. The drug-loading capacity of ATRA-PNP-CD20 was 8.7%, and ATRA-PNP-CD20 displayed a sustained release of ATRA for 144 hours. The results showed that ATRA-PNP-CD20 could effectively and specifically deliver ATRA to CD20+ melanoma-initiating cells, achieving superior inhibitory effects against CD20+ melanoma-initiating cells compared with those of free ATRA and nontargeted nanoparticles. To the best of our knowledge, we report for the first time a potent activity of ATRA against CD20+ melanoma-initiating cells, targeted drug delivery of ATRA via nanoparticles to melanoma-initiating cells, and the achievement of a superior inhibitory effect against melanoma-initiating cells by using a CD20 antibody.ConclusionATRA-PNP-CD20 represents a promising tool for eliminating melanoma-initiating cells and shows a potential for the therapy of melanoma.

Hyaluronic acid-coated nanoemulsions loaded with a hydrophobic ion pair of all-trans retinoic acid for improving the anticancer activity

All-trans retinoic acid (ATRA) has been studied for the treatment of cancer, including leukemia and breast cancer. This work aims to develop nanoemulsions (NE) loaded with a hydrophobic ion pair (HIP) of all-trans retinoic acid (ATRA) and a lipophilic amine, stearylamine (SA), and coated with hyaluronic acid (HA) to enhance anticancer activity and reducing toxicity. Blank NE was prepared by spontaneous emulsification and optimized prior to HIP incorporation. NE-ATRA was electrostatically coated with different concentrations of HA. Incorporation of ATRA-SA led to monodisperse NE with small size (129 ± 2 nm; IP 0.18 ± 0.005) and positive zeta potential (35.7 ± 1.0 mV). After coating with 0.5 mg/mL HA solution, the mean diameter slightly increased to 158 ± 5 nm and zeta potential became negative (-19.7 ± 1.2 mV). As expected, high encapsulation efficiency (near 100%) was obtained, confirmed by polarized light microscopy and infrared analysis. Formulations remained stable over 60 days and release of ATRA from NE was delayed after the hydrophilic HA-coating. HA-coated NE-ATRA was more cytotoxic than free ATRA for MDA-MB-231 and MCF-7 breast cancer cell lines, especially in the CD44 overexpressing cells. Blank coated formulations showed no cytotoxicity. These findings suggest that this easily-made HA-coated NE-ATRA formulation is a promising alternative for parenteral administration, thus improving the breast cancer therapy with this drug.

Nanostructured Lipid Carriers (NLC) for Parenteral Delivery of an Anticancer Drug

The purpose of this research was to formulate nanostructured lipid carriers (NLC) for the parenteral delivery of an anticancer drug, all-trans retinoic acid (ATRA). The ATRA was incorporated into NLC by the de novo emulsification method. The effect of the formulation factor, i.e., type and oil ratio, initial ATRA concentration on physicochemical properties was determined. The anticancer efficacy of ATRA-loaded NLC on HL-60 and HepG2 cells was also studied. NLC was formulated using a blend of solid lipids (cetyl palmitate) and liquid lipids (soybean oil (S), medium-chain triglyceride (M), S/oleic acid (O; 3:1) and M/O (3:1)) at a weight ratio of 1:1. ATRA-loaded NLC had an average size of less than 200 nm (141.80 to 172.95 nm) with a narrow PDI and negative zeta potential that was within an acceptable range for intravenous injection. The results indicated that oleic acid enhanced the ATRA-loading capacity of NLC. In vitro ATRA release was only approximately 4.06% to 4.34% for 48 h, and no significant difference in ATRA release rate from all NLC formulations in accordance with the composition of the oil phase. Moreover, no burst release of the drug was observed, indicating that NLC could prolong the release of ATRA. The initial drug concentration affected the photodegradation rate but did not affect the release rate. All ATRA-loaded NLC formulations exhibited the photoprotective property. The cytotoxicity results showed that all ATRA-loaded NLC had higher cytotoxicity than the free drug and HL-60 cells were more sensitive to ATRA than HepG2 cells.

Influence of histidine on the release of all-trans retinoic acid from self-assembled glycol chitosan nanoparticles

Objective: In this study, the influence of N-acetyl histidine (NAHis) on the all-trans retinoic acid (ATRA) release from the NAHis-conjugated self-assembled glycol chitosan (GC) nanoparticles was investigated. Methods: NAHis was conjugated to GC as a hydrophobic moiety to prepare the self-assembled nanoparticles, and ATRA was incorporated into the inner core of the NAHis–GC nanoparticles. The ATRA release from NAHis–GC nanoparticles was performed at 37°C in a phosphate-buffered saline buffer (pH 5.5 or 7.4) for 48 hours. Results: At a pH of 5.5, less than 20% (w/w) of total loading amount of ATRA was released from the nanoparticles after 48 hours. In contrast, two times greater amount of ATRA was released at a pH of 7.4. The ATRA release rate from the NAHis–GC nanoparticles was significantly slower at a pH of 5.5 than at a pH of 7.4. Conclusion: The release profiles of ATRA that was incorporated into the NAHis–GC nanoparticles were controlled by the NAHis content in the GC nanoparticles.

Preparation and characterization of chitosan-treated alginate microparticles incorporating all-trans retinoic acid

Chitosan treated alginate microparticles were prepared with the purpose of incorporating all-trans retinoic acid (ATRA) using an inexpensive, simple and fast method, enhancing dermal localization and sustaining the release of ATRA into the skin. Microparticles characterization, drug–polymer interaction, release profile and in vitro skin retention were investigated. Microparticles presented spherical shape and drug loading capacity of 47%. The drug content of these microparticles was affected by ATRA concentration and by the solvent used and it was more weakly affected by chitosan concentration. The release of ATRA was also affected by chitosan concentration. Microparticles prepared with 0.4% chitosan (w/w) resulted in drug release with a more sustained profile. The results of in vitro retention studies showed that chitosan treated alginate microparticles decreased the drug retention in the stratum corneum (SC), where occur the skin irritation, but maintained the ATRA concentration in the deeper skin layers, where occur the pathologies treated with ATRA. Then, the microparticles developed in this work can be a good candidate to improve the topical therapy with retinoid.

Release of All-Trans Retinoic Acid (RA) from RA-Loaded Poly(Ester Amine) Based on Polyethylenimine and Polycaprolactone for Intracellular Delivery

The objective of this study is to develop a new type of cationic nanoparticles for the intracellular drug delivery to breast cancer. Poly(ester amine) (PEA) based on polyethylenimine and polycaprolactone was synthesized to make cationic PEA nanoparticles for all-trans retinoic acid (RA). In the 1H-NMR study, the proton signals of RA appeared in the spectrum of RA-loaded PEA nanoparticles in CDCL3, whereas they disappeared in D2O, suggesting that hydrophobic inner-core with hydrophilic outer-shell formed in water. RA release was faster at lower drug content and RA was released over a period of 20 days. RA-loaded PEA nanoparticles showed enhanced cytotoxicity compared with RA itself, whereas nanoparticles of PEA themselves did not show it. These results indicated that the cationic PEA provided an efficient intracellular delivery of RA.