In vivo biocompatibility and efficacy of dexamethasone-loaded PLGA-PEG-PLGA thermogel in an alkali-burn induced corneal neovascularization disease model.

Challenges of ophthalmic drug delivery arise not only from the limited solubility of hydrophobic therapeutics, but also the restricted permeability and fast clearance of drugs due to the complex anatomy and physiology of eyes. Excellent biocompatibility of a thermosensitive polymer, PLGA-PEG-PLGA (1800-1500-1800, LA:GA ratio = 3:1), as an ophthalmic delivery system was demonstrated in our previous work. In this study, delivery of dexamethasone using this thermogel via a single subconjunctival injection for prolonged treatment was evaluated with corneal neovascularization using an alkali-burn diseased model in rat. Solubility of dexamethasone in the polymeric solution was increased by 5.2-fold and the resulting drug-loaded solution formed in situ rigid gel at body temperature. Prolonged in vitro release of dexamethasone from the gel structure was noted. Dexamethasone gel formulation was demonstrated to be more effective in reducing the burn stimulus and neovascularization in the rat diseased model. The findings suggest the PLGA-PEG-PLGA in situ gelling system can be applied for ophthalmic drug delivery to achieve sustained drug release and improved efficacy.

Engineering red-emitting multi-functional nanocapsules for magnetic tumour targeting and imaging.

In this work we describe the formulation and characterisation of red-emitting polymeric nanocapsules (NCs) incorporating superparamagnetic iron oxide nanoparticles (SPIONs) for magnetic tumour targeting. The self-fluorescent oligomers were synthesised and chemically conjugated to PLGA which was confirmed by NMR spectroscopy, FT-IR spectroscopy and mass spectrometry. Hydrophobic SPIONs were synthesised through thermal decomposition and their magnetic and heating properties were assessed by SQUID magnetometry and calorimetric measurements, respectively. Magnetic nanocapsules (m-NCs) were prepared by a single emulsification/solvent evaporation method. Their in vitro cytotoxicity was examined in CT26 colon cancer cells. The formulated fluorescent m-NCs showed good stability and biocompatibility both in vitro and in vivo in CT 26 colon cancer models. Following intravenous injection, accumulation of m-NCs in tumours was observed by optical imaging. A higher iron content in the tumours exposed to a magnetic field, compared to the contralateral tumours without magnetic exposure in the same animal, further confirmed the magnetic tumour targeting in vivo. The overall results show that the engineered red-emitting m-NCs have great potential as multifunctional nanocarriers for multi-model bioimaging and magnetic-targeted drug delivery.

An injectable recombinant human milk fat globule-epidermal growth factor 8-loaded copolymer system for spinal cord injury reduces inflammation through NF-κB and neuronal cell death.

Spinal cord injury (SCI) is a common disease and a major cause of paralysis, carrying much burden around the world. Despite the progress made with growth factors therapy, the response rate of acute SCI treatment still remains unsatisfactory, due largely to complex and severe inflammatory reactions. Herein, we prepare a MFG-E8-loaded copolymer system-based anti-inflammation therapy for SCI treatment. It is shown that the MFG-E8-loaded copolymer system can decrease pro-inflammatory cytokine expression and neuron death. In a rat model of crush-caused SCI, the copolymer system shows significant therapeutic efficacy by ameliorating inflammation, decreasing fibrotic scar, promoting myelin regeneration and suppressing overall SCI severity.

Prophylactic onlay reinforcement with absorbable mesh (polyglactin) is associated with less early wound complications after kidney transplantation: A preliminary study.

Incidence of wound complications after kidney transplantation (KTx) is still considerable. Here, we report the impact of prophylactic absorbable polyglactin (Vicryl®) mesh reinforcement on the incidence of short-term post-KTx wound complications. Sixty-nine patients were analyzed; 23 with and 46 without preventive onlay mesh reinforcement. Surgical site infections (SSI) were seen in six (26%) patients in the mesh group and in 17 (37%) patients in no-mesh group. A lower, but not statistically significant, rate of early postoperative wound complications occurred in the mesh group. Wound complications were observed in seven (30%) patients in the mesh group and in 23 (50%) patients in the no-mesh group. There was no association between mesh placement and SSI incidence (odds ratios [OR] 0.60, 95% confidence interval [CI] 0.20-1.82, p = 0.369) and wound complications (OR 0.44, 95% CI 0.15-1.26, p = 0.126). Therefore, we conclude that mesh reinforcement does not increase the risk of SSI and overall wound complications. Long-term outcomes have to be evaluated in a randomized trial setting. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:67-72, 2020.

Comparison of Surgisis, Vypro II and TiMesh in contaminated and clean field.

PURPOSE: The study aimed to evaluate the histologic properties and infection resistance of three different mesh materials in a rat model. METHODS: Each mesh, in both infectious (n = 96) and non-infectious groups (n = 270), was positioned both in sublay (preperitoneally) and onlay (subcutaneously) locations. Properties of the biological (Surgisis; Cook Surgical), composite, partially resorbing (Vypro II mesh; Ethicon) and non-resorbing (TiMesh; GFE Medizintechnik GmbH) mesh were evaluated and compared. Animals were killed at 7, 21 and 90 days after implantation. The following parameters were evaluated to assess the host response to the mesh material: inflammation, vascularization, fibrosis, collagen formation, Ki67, and a foreign body reaction by granuloma formation (FBG). RESULTS: Surgisis mesh produced more pronounced inflammation and cell proliferation, and less intense granuloma formation, as well as fibrosis, compared to the other two groups. When the infected materials were examined, we found signs of local infection to be more often present in Surgisis group of animals. CONCLUSIONS: In the presence of bacterial contamination, no benefits were observed in the use of the Surgisis prosthesis over the use of TiMesh and Vypro II.

Inorganic Gold and Polymeric Poly(Lactide-co-glycolide) Nanoparticles as Novel Strategies to Ameliorate the Biological Properties of Antimicrobial Peptides.

Cationic antimicrobial peptides (AMPs) are an interesting class of gene-encoded molecules endowed with a broad-spectrum of anti-infective activity and immunomodulatory properties. They represent promising candidates for the development of new antibiotics, mainly due to their membraneperturbing mechanism of action that very rarely induces microbial resistance. However, bringing AMPs into the clinical field is hampered by some intrinsic limitations, encompassing low peptide bioavailability at the target site and high peptide susceptibility to proteolytic degradation. In this regard, nanotechnologies represent an innovative strategy to circumvent these issues. According to the literature, a large variety of nanoparticulate systems have been employed for drug-delivery, bioimaging, biosensors or nanoantibiotics. The possibility of conjugating different types of molecules, including AMPs, to these systems, allows the production of nanoformulations able to enhance the biological profile of the compound while reducing its cytotoxicity and prolonging its residence time. In this minireview, inorganic gold nanoparticles (NPs) and biodegradable polymeric NPs made of poly(lactide-coglycolide) are described with particular emphasis on examples of the conjugation of AMPs to them, to highlight the great potential of such nanoformulations as alternative antimicrobials.

Transpancreatic mattress suture with Vicryl mesh around the stump decreases postoperative pancreatic fistula after distal pancreatectomy.

BACKGROUND: Postoperative pancreatic fistula (POPF) after distal pancreatectomy (DP) remains the most common surgical complication. We have developed a novel stump closure technique after DP using transpancreatic mattress suture with Vicryl mesh (TMV) and reported our initial findings. The purpose of this study is to evaluate the efficacy of TMV compared to the conventional handsewn stump closure technique (CHS). METHODS: This retrospective single-center study included 165 consecutive patients who underwent open DP from January 2010 to May 2018. Of these, 71 patients underwent DP using TMV after September 2014 and 94 patients underwent DP with CHS. The surgical outcomes were compared between the two groups. RESULTS: Clinically relevant POPF rate in the TMV group was significantly lower than that in the CHS group (5.6% vs. 17.2%, P = 0.027). Morbidity rate was higher in the CHS group than that in the TMV group (16.9% vs. 27.7%, P = 0.104). In the multivariate analysis, absence of additional organ resection (OR 3.57; 95% CI 1.18-10.43; P = 0.025) and TMV (OR 0.24; 95% CI 0.07-0.73; P = 0.010) were identified as independent preventing factors for clinically relevant POPF. CONCLUSION: TMV can be an effective stump closure technique for preventing POPF after DP.

Biodegradable Thermosensitive PLGA-PEG-PLGA Polymer for Non-irritating and Sustained Ophthalmic Drug Delivery.

Challenges of ophthalmic drug delivery arise from not only the limited solubility of hydrophobic therapeutics, but also the restricted permeability and fast clearance of drugs due to the complex anatomy and physiology of the eyes. Biodegradable thermosensitive polymer, poly(dl-lactide-co-glycolide-b-ethylene glycol-b-dl-lactide-co-glycolide) (PLGA-PEG-PLGA) is a desirable ophthalmic drug delivery system because it can be formulated into injectable solution which forms gel in situ to provide prolonged drug release. In this study, excellent biocompatibility of blank PLGA-PEG-PLGA (1800-1500-1800) thermogel was demonstrated with insignificant difference from saline noted in rat eye enucleation test, in vivo inflammation test upon topical instillation, and subconjunctival injection. After subconjunctival injection, thermogel formulations loaded with hydrophilic (rhodamine B) or hydrophobic (coumarin 6) fluorescent dyes were retained up to 4 weeks in eye tissues and significantly higher level was detected than rhodamine B solution or coumarin 6 suspension in weeks 3 and 4. Moreover, in vivo whole body imaging showed that dye-loaded (sulfo-cyanine 7 NHS ester, Cy7; or cyanine 7.5 alkyne, Cy7.5) thermogels had longer retention at the injection site and retarded release to other body parts than dye solutions. Generally, the release rate of hydrophobic dyes (coumarin 6 and Cy7.5) was much slower than that of the hydrophilic dyes (rhodamine B and Cy7) from the thermogel. In summary, the thermogel was safe for ophthalmic drug delivery and could deliver both hydrophobic and hydrophilic compounds for sustained drug release into eye tissues with single subconjunctival injection for better patient compliance and reduced risks on repeated injection.

A thermo-responsive and self-healing liposome-in-hydrogel system as an antitubercular drug carrier for localized bone tuberculosis therapy.

Isoniazid (INH) is a first-line therapy for bone tuberculosis (TB), but its clinic benefits are limited by severe side-effects after long-time administration. While nano-drug delivery systems present as promising strategies for INH delivery, the therapeutic efficacies are usually suboptimal due to ineffective drug accumulation at diseased sites. Local delivery system can achieve high drug concentration at focus sites with minimal systemic exposure, and herein we aimed to employ this strategy to develop a novel liposome-in-hydrogel system for localized treatment of bone TB. To achieve sustainable drug release, a derivative of INH called DINH was loaded because of its hydrophobicity, as well as its better activity and higher biosafety than INH. The hybrid system was demonstrated for thermo-responsive and self-healing properties via phase transition test and rheological studies, which were particularly useful for intra-articular administration. In vivo microdialysis studies revealed that the system can rapidly release drug into synovial fluid to reach effective inhibitory concentrations after localized injection, followed by a steady-state drug release. The optical image studies were performed to study its long-term behavior in vivo, which suggested a sustained drug release profile for several days. This work provides a promising drug delivery system for bone TB therapy.

Local Toxicity of Topically Administrated Thermoresponsive Systems: In Vitro Studies with In Vivo Correlation.

Thermoresponsive materials have the ability to respond to a small change in temperature-a property that makes them useful in a wide range of applications and medical devices. Although very promising, there is only little conclusive data about the cytotoxicity and tissue toxicity of these materials. This work studied the biocompatibility of three Food and Drug Administration approved thermoresponsive polymers: poly( N-isopropyl acrylamide), poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) tri-block copolymer, and poly(lactic acid-co-glycolic acid) and poly(ethylene glycol) tri-block copolymer. Fibroblast NIH 3T3 and HaCaT keratinocyte cells were used for the cytotoxicity testing and a mouse model for the in vivo evaluation. In vivo results generally showed similar trends as the results seen in vitro, with all tested materials presenting a satisfactory biocompatibility in vivo. pNIPAM, however, showed the highest toxicity both in vitro and in vivo, which was explained by the release of harmful monomers and impurities. More data focusing on the biocompatibility of novel thermoresponsive biomaterials will facilitate the use of existing and future medical devices.

Development and Characterization of Olanzapine Loaded Poly(lactide-coglycolide) Microspheres for Depot Injection: In vitro and In vivo Release Profiles.

PURPOSE: The purpose of this study was to develop a new PLGA based microsphere formulation aimed to release the olanzapine for the period of one month which will result in increased compliance. METHODS: Microspheres loaded with olanzapine were prepared using oil in water emulsion and solvent evaporation technique. The microspheres were characterized by surface morphology, shape, size, bulk density, encapsulation efficiency, and Fourier transform infrared spectrometry. In vitro release studies were performed in phosphate buffer at 37°C and in vivo studies were conducted on male Sprague- Dawley rats. RESULTS: The morphological results indicated that microspheres produced were having a smooth surface, spherical shape and the size in the range from 9.71 to 19.90 µm mean diameter. Encapsulation efficiency of olanzapine loaded microspheres was in the range of 78.53 to 96.12% and was affected by changing the ratio of lactic to glycolic acid in copolymer PLGA. The properties of PLGA and other formulation parameters had a significant impact on in vitro and in vivo release of drug from microspheres. In vitro release kinetics revealed that release of drug from microspheres is by both non-Fickian diffusion and erosion of PLGA polymer. In vivo data indicated an initial burst release and then sustained release depending on properties of PLGA, microsphere size, and bulk density. CONCLUSION: This study indicates that microsphere formulations developed with PLGA (75:25) and PLGA (85:15) have provided a sufficient steady release of drug for at least 30 days and can be potential candidates for 30-day depot injection drug delivery of olanzapine.

Combination of a Bioceramic Scaffold and Simvastatin Nanoparticles as a Synthetic Alternative to Autologous Bone Grafting.

The fragile nature of porous bioceramic substitutes cannot match the toughness of bone, which limits the use of these materials in clinical load-bearing applications. Statins can enhance bone healing, but it could show rhabdomyolysis/inflammatory response after overdosing. In this study, the drug-containing bone grafts were developed from poly(lactic acid-co-glycolic acid)-polyethylene glycol (PLGA-PEG) nanoparticles encapsulating simvastatin (SIM) (SIM-PP NPs) loaded within an appropriately mechanical bioceramic scaffold (BC). The combination bone graft provides dual functions of osteoconduction and osteoinduction. The mechanical properties of the bioceramic are enhanced mainly based on the admixture of a combustible reverse-negative thermoresponsive hydrogel (poly(N-isopropylacrylamide base). We showed that SIM-PP NPs can increase the activity of alkaline phosphatase and osteogenic differentiation of bone marrow stem cells. To verify the bone-healing efficacy of this drug-containing bone grafts, a nonunion radial endochondral ossification bone defect rabbit model (N = 3/group) and a nonunion calvarial intramembranous defect Sprague Dawley (SD) rat model (N = 5/group) were used. The results indicated that SIM-PP NPs combined with BC can improve the healing of nonunion bone defects of the radial bone and calvarial bone. Therefore, the BC containing SIM-PP NPs may be appropriate for clinical use as a synthetic alternative to autologous bone grafting that can overcome the problem of determining the clinical dosage of simvastatin drugs to promote bone healing.

Comparative study of fibrosis induced by Marlex®, Parietex Composite®, Vicryl® and Ultrapro® meshes1.

PURPOSE: To evaluate the fibrosis induced by four different meshes: Marlex®, Parietex Composite®, Vicryl® and Ultrapro®. METHODS: Histological cutouts of abdominal wall were analyzed with polarized light 28 days after the meshes implants and colorized by picrosirius to identify the intensity of collagen types I and III, and their maturation index. RESULTS: When the four groups were compared, the total collagen area analyzed was bigger in groups A and D, with no difference between them. The collagen type I density was bigger in group A, with an average of 9.62 ± 1.0, and smaller in group C, with an average of 3.86 ± 0.59. The collagen type III density was similar in groups A, B and C, and bigger in group D. The collagen maturation index was different in each of the four groups, bigger in group A with 0.87, group B with 0.66, group D with 0.57 and group C with 0.33 (p = 0.0000). CONCLUSION: The most prominent fibrosis promotion in the given meshes was found on Marlex® (polypropylene mesh) and the Parietex Composite® (non-biodegradable polyester); the collagen maturation index was higher in the Marlex® mesh, followed by Ultrapro®, Parietex Composite® and Vicryl® meshes.

Targeted folate-conjugated pluronic P85/poly(lactide-co-glycolide) polymersome for the oral delivery of insulin.

AIM: To explore the better efficacy of targeted folic acid (FA)-Pluronic 85-poly(lactide-co-glycolide) (FA-P85-PLGA) polymersome in oral insulin delivery. MATERIALS & METHODS: The cytotoxicity of the polymers, in vitro qualitative and quantitative cellular uptake and the internalization mechanism of insulin-loaded FA-P85-PLGA and PLGA-P85-PLGA polymersomes were studied with the human colon adenocarcinoma cells (Caco-2 cells). Their pharmacodynamics and pharmacokinetics properties were also studied with diabetic rats. RESULTS & CONCLUSION: Polymersomes have shown good biocompatibility. Polymersomes are mainly localized within the cytoplasm of Caco-2 cells from fluorescence microscopy images. FA-P85-PLGA exhibited higher cellular uptake than PLGA-P85-PLGA polymersomes and free fluorescein isothiocyanate-labeled insulin (FITC-insulin) did. The uptake process of targeted polymersomes included clathrin- and caveolae-mediated endocytosis, macropinocytosis and the folate receptor-mediated endocytosis. Insulin-loaded FA-P85-PLGA showed better hypoglycemic effects than insulin-loaded PLGA-P85-PLGA.

Comparative study of fibrosis induced by Marlex®, Parietex Composite®, Vicryl® and Ultrapro® meshes1

Abstract Purpose: To evaluate the fibrosis induced by four different meshes: Marlex®, Parietex Composite®, Vicryl® and Ultrapro®. Methods: Histological cutouts of abdominal wall were analyzed with polarized light 28 days after the meshes implants and colorized by picrosirius to identify the intensity of collagen types I and III, and their maturation index. Results: When the four groups were compared, the total collagen area analyzed was bigger in groups A and D, with no difference between them. The collagen type I density was bigger in group A, with an average of 9.62 ± 1.0, and smaller in group C, with an average of 3.86 ± 0.59. The collagen type III density was similar in groups A, B and C, and bigger in group D. The collagen maturation index was different in each of the four groups, bigger in group A with 0.87, group B with 0.66, group D with 0.57 and group C with 0.33 (p = 0.0000). Conclusion: The most prominent fibrosis promotion in the given meshes was found on Marlex® (polypropylene mesh) and the Parietex Composite® (non-biodegradable polyester); the collagen maturation index was higher in the Marlex® mesh, followed by Ultrapro®, Parietex Composite® and Vicryl® meshes.

In situ low-immunogenic albumin-conjugating-corona guiding nanoparticles for tumor-targeting chemotherapy.

Nanoparticles (NPs) are unavoidably covered by a layer of immunogenic proteins upon injection into blood, such as immunoglobins and complements, which buries the active-targeting ligands and triggers the rapid clearance of NPs by the mononuclear phagocytic system. Low antifouling polyethylene glycol is used to inhibit the formation of the immunogenic corona but it leads to poor cellular uptake and the immunogen-related accelerated blood clearance (ABC) phenomenon in multiple administrations. Here, we develop surface maleimide-modified NPs that covalently conjugate in vivo plasma albumin in its corona upon exposure to blood. The in situ recruited low-immunogenic albumin-enriching corona is capable of protecting maleimide-decorated NPs from phagocytosis in the bloodstream, preventing the ABC phenomenon in the second administration, facilitating NP accumulation in the tumor site/cells by the passive EPR effect and albumin receptor-mediated active targeting, and finally improving the antitumor activity. Such findings suggest that the facile strategy, based on the in situ anchored albumin-enriching corona, is efficient at enabling maleimide-decorated NPs to acquire stealth and tumor-targeting ability.

Polygalacin D induces apoptosis and cell cycle arrest via the PI3K/Akt pathway in non-small cell lung cancer.

Polygalacin D (PGD) is a bioactive compound isolated from Platycodon grandiflorum (Jacq.) and it has a similar structure to platycodin D, which is a well known anticancer agent. In the present study, we investigated the anti-proliferative effects of PGD using NSCLC cell lines. We evaluated the effects of PGD on proliferation, apoptosis and cell cycle arrest in A549 and H460 cells. PGD significantly induced apoptosis and nuclear condensation in both cell lines. Furthermore, PGD upregulated the cleavage of apoptotic proteins such as caspase-3, -9 and PARP. Additionally, treatment with PGD suppressed the expression of the IAP family of proteins including survivin, cIAP-1 and cIAP-2. Furthermore, PGD induced G0/G1-phase arrest in both cell lines. After treatment with PGD, the expression of TIMP-1, CDK2, cyclin A and cyclin E was reduced at the protein level. In addition, PGD blocked the PI3K/Akt pathway by inhibiting the phosphorylation of GSK3ß, Akt and the expression of PI3K. Our results indicated that the anti-proliferative properties of PGD may result from the regulation of the PI3K/Akt pathway, which plays a critical role in cell survival and growth.

Development of a non-toxic and non-denaturing formulation process for encapsulation of SDF-1α into PLGA/PEG-PLGA nanoparticles to achieve sustained release.

Chemokines are known to stimulate directed migration of cancer cells. Therefore, the strategy involving gradual chemokine release from polymeric vehicles for trapping cancer cells is of interest. In this work, the chemokine stromal cell-derived factor-1α (SDF-1α) was encapsulated into nanoparticles composed of poly-(lactic-co-glycolic acid) (PLGA) and a polyethylene glycol (PEG)-PLGA co-polymer to achieve sustained release. SDF-1α, and lysozyme as a model protein, were firstly precipitated to promote their stability upon encapsulation. A novel phase separation method utilising a non-toxic solvent in the form of isosorbide dimethyl ether was developed for the individual encapsulation of SDF-1α and lysozyme precipitates. Uniform nanoparticles of 200-250 nm in size with spherical morphologies were successfully synthesised under mild formulation conditions and conveniently freeze-dried in the presence of hydroxypropyl-ß-cyclodextrin as a stabiliser. The effect of PLGA carboxylic acid terminal capping on protein encapsulation efficiency and release rate was also explored. Following optimisation, sustained release of SDF-1α was achieved over a period of 72 h. Importantly, the novel encapsulation process was found to induce negligible protein denaturation. The obtained SDF-1α nanocarriers may be subsequently incorporated within a hydrogel or other scaffolds to establish a chemokine concentration gradient for the trapping of glioblastoma cells.

Nanoparticles obtained by confined impinging jet mixer: poly(lactide-co-glycolide) vs. Poly-ε-caprolactone.

This paper is focused on the production and characterization of polymeric nanoparticles obtained by nanoprecipitation. The method consisted of using a confined impinging jet mixer (CIJM), circumventing high-energy equipment. Differences between the use of poly-ε-caprolactone (PCL) and poly(lactide-co-glycolide) (PLGA) as concerns particle mean size, zeta potential, and broad-spectrum antibiotic florfenicol entrapment were investigated. Other analyzed variables were polymer concentration, solvent, and anti-solvent flow rates, and antibiotic initial concentration. To our knowledge, no data were found related to PLGA and PCL nanoparticles comparison using CIJM. Also, florfenicol encapsulation within PCL or PLGA nanoparticles by nanoprecipitation has not been reported yet. The complexity of the nanoprecipitation phenomena has been confirmed, with many relevant variables involved in particles formation. PLGA resulted in smaller and more stable nanoparticles with higher entrapping of florfenicol than PCL.

RNA nanoparticle distribution and clearance in the eye after subconjunctival injection with and without thermosensitive hydrogels.

Thermodynamically and chemically stable RNA nanoparticles derived from the three-way junction (3WJ) of the pRNA from bacteriophage phi29 DNA packaging motor were examined previously for ocular delivery. It was reported that, after subconjunctival injection, RNA nanoparticles with tri-way shape entered the corneal cells but not the retinal cells, whereas particle with four-way shape entered both corneal and retinal cells. The present study evaluated ocular delivery of RNA nanoparticles with various shapes and sizes, and assessed the effect of thermosensitive hydrogels (poly(lactic-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(lactic-co-glycolic acid); PLGA-PEG-PLGA) for increasing the retention of RNA nanoparticles in the eye. Fluorescence imaging of mouse eyes and fluorescence microscopy of dissected eye tissues from the conjunctiva, cornea, retina, and sclera were performed to determine the distribution and clearance of the nanoparticles in the eyes after subconjunctival injection in vivo. RNA nanoparticles entered the cells of the conjunctiva, cornea, retina, and sclera after subconjunctival delivery. The clearance of RNA pentagon was slower than both RNA square and triangle of the same designed edge length (10nm) in the eye, and the clearance of RNA squares of the longer edge lengths (10 and 20nm) was slower than RNA square of the shorter edge length (5nm), thus indicating that the size could affect ocular pharmacokinetics of the nanoparticles. At 24h after the injection, approximately 6-10% of the fluorescence signal from the larger nanoparticles in the study (RNA square of 20nm edge length and RNA pentagon of 10nm edge length) remained in the eye, and up to 70% of the retinal cells contained the nanoparticles. The results suggest that the larger nanoparticles were "gulped" in conjunctival, corneal, retinal, and scleral cells, similar to the behavior observed in macrophages. Additionally, the combination of RNA nanoparticles with the thermosensitive polymers increased the retention of the nanoparticles in the eye.