Sarbani Hazra

Pirfenidone nanoparticles improve corneal wound healing and prevent scarring following alkali burn.

Purpose To evaluate the effects of pirfenidone nanoparticles on corneal re-epithelialization and scarring, major clinical challenges after alkali burn. Methods Effect of pirfenidone on collagen I and α-smooth muscle actin (α-SMA) synthesis by TGFβ induced primary corneal fibroblast cells was evaluated by immunoblotting and immunocytochemistry. Pirfenidone loaded poly (lactide-co-glycolide) (PLGA) nanoparticles were prepared, characterized and their cellular entry was examined in primary corneal fibroblast cells by fluorescence microscopy. Alkali burn was induced in one eye of Sprague Dawley rats followed by daily topical treatment with free pirfenidone, pirfenidone nanoparticles or vehicle. Corneal re-epithelialization was assessed daily by flourescein dye test; absence of stained area indicated complete re-epithelialization and the time for complete re-epithelialization was determined. Corneal haze was assessed daily for 7 days under slit lamp microscope and graded using a standard method. After 7 days, collagen I deposition in the superficial layer of cornea was examined by immunohistochemistry. Results Pirfenidone prevented (P<0.05) increase in TGF β induced collagen I and α-SMA synthesis by corneal fibroblasts in a dose dependent manner. Pirfenidone could be loaded successfully within PLGA nanoparticles, which entered the corneal fibroblasts within 5 minutes. Pirfenidone nanoparticles but not free pirfenidone significantly (P<0.05) reduced collagen I level, corneal haze and the time for corneal re-epithelialization following alkali burn. Conclusion Pirfenidone decreases collagen synthesis and prevents myofibroblast formation. Pirfenidone nanoparticles improve corneal wound healing and prevent fibrosis. Pirfenidone nanoparticles are of potential value in treating corneal chemical burns and other corneal fibrotic diseases.

Multifunctional and multitargeted nanoparticles for drug delivery to overcome barriers of drug resistance in human cancers

The recurrence and metastatic spread of cancer are major drawbacks in cancer treatment. Although chemotherapy is one of the most effective methods for the treatment of metastatic cancers, it is nonspecific and causes significant toxic damage. The development of drug resistance to chemotherapeutic agents through various mechanisms also limits their therapeutic potential. However, as we discuss here, the use of nanodelivery systems that are a combination of diagnostics and therapeutics (theranostics) is as relatively novel concept in the treatment of cancer. Such systems are likely to improve the therapeutic benefits of encapsulated drugs and can transit to the desired site, maintaining their pharmaceutical properties. The specific targeting of malignant cells using multifunctional nanoparticles exploits theranostics as an improved agent for delivering anticancer drugs and as a new solution for overriding drug resistance.

Use of ketamine, xylazine, and diazepam anesthesia with retrobulbar block for phacoemulsification in dogs

OBJECTIVE The study was undertaken to evaluate the use of ketamine, xylazine, and diazepam along with a local retrobulbar nerve block for routine phacoemulsification in the dog. Animals Ten clinically healthy mixed-breed dogs of either sex, weighing between 10 and 15 kg. PROCEDURES Ten mixed-breed dogs were selected for unilateral cataract removal by phacoemulsification. Standard preoperative preparations for cataract surgery were followed. Pre-anesthetic medication consisted of atropine sulfate (0.02 mg/kg, SC). Anesthesia was induced by xylazine HCl (1.0 mg/kg, IM) followed by ketamine (5.0 mg/kg, IM). Anesthesia was maintained subsequently with IV ketamine and diazepam to effect and depth of anesthesia was assessed clinically by pedal reflex and jaw reflex. After induction of anesthesia, a retrobulbar nerve block was performed using 2 mL of 2% lignocaine. Eye position was graded after retrobulbar block and IOP was examined preoperative, post-anesthetic, 6 h postoperative and 24 h after surgery. Phacoemulsification was performed using the phaco-chop technique and an intraocular lens was placed. Anesthetic recovery and postoperative recovery following surgery was recorded. RESULT The exposure of the globe in all the dogs was adequate; the desired central fixation of the eye was obtained and surgery could be performed uneventfully. The mean IOP recorded after induction of anesthesia was 15.75 +/- 0.82, which was not significantly (P > 0.01) different from pre-anesthetic values (14.85 +/- 0.85). CONCLUSION Phacoemulsification was successfully performed with this anesthetic regimen without encountering major intraoperative or anesthetic complications.

Non-mulberry Silk Fibroin Biomaterial for Corneal Regeneration.

Purpose: Successful repair of a damaged corneal surface is a great challenge and may require the use of a scaffold that supports cell growth and differentiation. Amniotic membrane is currently used for this purpose, in spite of its limitations. A thin transparent silk fibroin film from non-mulberry Antheraea mylitta (Am) has been developed which offers to be a promising alternative. The silk scaffolds provide sufficient rigidity for easy handling, the scaffolds support the sprouting, migration, attachment and growth of epithelial cells and keratocytes from rat corneal explants; the cells form a cell sheet, preserve their phenotypes, express cytokeratin3 and vimentin respectively. The films also support growth of limbal stem cell evidenced by expression of ABCG2. The cell growth on the silk film and the amniotic membrane is comparable. The implanted film within the rabbit cornea remains transparent, stable. The clinical examination as well as histology shows absence of any inflammatory response or neovascularization. The corneal surface integrity is maintained; tear formation, intraocular pressure and electroretinography of implanted eyes show no adverse changes. The silk fibroin film from non-mulberry silk worms may be a worthy candidate for use as a corneal scaffold.

Comparison of design of intraocular lens versus the material for PCO prevention.

AIM To evaluate the influence of different intraocular lens(IOL) designs made of PMMA on posterior capsular opacification(PCO) and compare with foldable designs. METHODS Phacoemulsification and IOL implantation was done in one eye of 24 New Zealand White rabbits, with IOL of two different designs (Square edged or round edge) and two different materials(PMMA or HEMA). After three months, the animals were sacrificed and enucleated. Evaluation of PCO included posterior view, migration of anterior capsular epithelial cells to the posterior capsule following epithelial-mesenchymal transition were assessed by staining the histological sections of posterior capsule by hematoxylin-eosin(HE) and Periodic acid- Schiff (PAS). The IOLs were extracted and stained with HE to evaluate the presence of adherent cells on the lens surface. RESULTS PCO was highest with round edged rigid lens. There was no significant difference in the PCO between the square edged PMMA and square edged foldable lens. CONCLUSION It is the design of the IOL not the material that offers protection on PCO formation.

Doxorubicin-loaded MePEG-PCL nanoparticles for prevention of posterior capsular opacification

AIMS Cytotoxic drugs are considered as potent candidates for the prevention of posterior capsular opacification (PCO), but the toxicity incited to healthy intraocular structures is a major concern. In this study, the authors evaluated the effect of PEG methyl ether-block-poly(ε-caprolactone) (MePEG-PCL) doxorubicin (DOX)-loaded nanoparticles (NPs) for prevention of PCO and their influence on intraocular tissues. METHODS MePEG-PCL DOX NPs were prepared and characterized. The cytotoxic effect of DOX NPs on lens epithelial cells was compared with free drug. Its effect on PCO prevention following single subconjunctival delivery to lensectomized rabbits was assessed. Toxicity to intraocular structures was evaluated by specular microscopy, electroretinography and histopathology. The availability of DOX in aqueous humor was determined by HPLC. RESULTS The cytotoxic effect of DOX NPs was higher compared with free DOX due to prolonged retention within the cells. A significant reduction in degree of PCO was observed in DOX NP-treated eyes compared with untreated controls. There was no significant change in the density and morphology of corneal endothelial cells or the histology of intraocular structures. Electroretinographs of treated eyes did not change compared with the pretreatment values. DOX could be detected by HPLC in the aqueous humor up to 48 h following single subconjunctival injection. CONCLUSION The authors conclude that DOX-loaded MePEG-PCL NPs show promise as a new approach to selectively kill highly proliferative lens epithelial cells in vivo following cataract surgery, while sparing normal tissue.

Curcumin nanoparticles inhibit corneal neovascularization.

Corneal neovascularization is a leading cause for compromised vision. Therapeutic prevention of corneal neovascularization is a major clinical challenge, and there is a compelling need to seek effective and safe therapy for this pathology. This study is aimed to evaluate curcumin nanoparticle for prevention of corneal neovascularization. MePEG-PCL nanoparticles were successfully prepared and characterized. The nanoparticle of curcumin has shown increased efficiency in preventing angiogenic sprouting in vitro. Topical delivery of curcumin nanoparticle in the eye showed enhanced retention of curcumin in the cornea, and significant improvement in prevention of corneal neovascularization over free curcumin as graded clinically and by histopathology; suppression in the expression of VEGF, inflammatory cytokines, and MMP was evidenced in the treated cornea. Curcumin inhibited NFκB in LPS-induced corneal cells. Histopathology and scanning electron microscopy showed absence of any adverse change in the corneal structure following application of curcumin nanoparticle. Therefore, we conclude that curcumin nanoparticle can be a potential candidate for prevention of corneal neovascularization.Key messageCurcumin nanoparticles show enhanced retention of curcumin in the cornea.Curcumin NPs suppress the expression of VEGF, inflammatory cytokines, and MMP.Curcumin NPs prevent corneal neovascularization by suppressing the NFκB pathway.Curcumin NPs may be a promising candidate for prevention of corneal neovascularization.

Influence of silver nanoparticles on post-surgical wound healing following topical application

Abstract Background: Prevention of surgical site infection and wound dehiscence are imperative and also challenging in clinical practice. This study examines the healing response of laparotomy wounds following application of silver nanoparticles. Materials and Methods: Dermal fibroblasts were exposed to incremential doses of silver nanoparticles and its effect on collagen synthesis and cytotoxicity was assessed. Laparotomy surgery was performed on rabbits and the operation site was treated topically either with silver nanoparticle once, or once daily for 14 days or with vehicle. Healing response and local tissue reaction was evaluated clinically by histopathology and scanning electron microscopy (SEM); microbial load on the operation site was assessed. Clinical tests and histopathology were performed to assess systemic toxicity. Results: Silver nanoparticles increased collagen expression from dermal fibroblasts and longer time exposure increased caspase 3 expression and produced cyotoxic effect with an IC50 of 0.16 mg/mL. Daily treatment of operation sites resulted in increased collagen deposition and improved wound healing, microbial load was reduced. Although a sub dermal edema was evident in histopathology, SEM showed normal architecture of cells with infiltration of lymphocytes. There was no systemic toxicity. Conclusions: Silver nanoparticles exhibit a positive influence on wound healing but its effect on local tissue remains a concern.

Influence of topical anesthetics on oculocardiac reflex and corneal healing in rabbits.

AIM To investigate the incidence of oculocardiac reflex (OCR) with two anesthetic regimens and its prevention using topical anesthetics in a rabbit model, and to explore the effect of topical anesthetics on corneal healing. METHODS Forty-eight clinically healthy adult New Zealand white rabbits of either sex were divided into two groups (Group A and B) and anesthetized with either ketamine (Group A, n =24) or propofol (Group B, n =24). he incidence of OCR was recorded in each group with a variety of ocular manipulation with or without the use of topical anesthetics (40g/L lignocaine, 5g/L proparacain, 5g/L bupivacaine). Corneal toxicity and healing following the use of each topical anesthetic was assessed one day after surgery and up to 7 days postoperatively by clinical examination of the eye, histopathology and collagen staining and transmission electron microscopy. RESULTS No incidence of OCR was recorded with ocular manipulation under ketamine anesthesia, whereas significant reduction in heart rate (P<0.01) was recorded under propofol anesthesia. Topical anesthetics could successfully prevent the OCR without affecting the corneal healing. CONCLUSION Topical anesthetics may be recommended for prevention of OCR without any local adverse effect.

In vitro drug release and in vivo safety of vitamin E and cysteamine loaded contact lenses

ABSTRACT Cystinosis is an orphan disease caused by a genetic mutation that leads to deposition of cystine crystals in many organs including cornea. Ophthalmic manifestation of the disease can be treated with hourly instillation of cysteamine eye drops. The hourly eye drop instillation is tedious to the patients leading to poor compliance and additionally, significant degradation of the drug occurs within one week of opening the bottle, which further complicates this delivery approach. This paper focuses on designing a contact lens to treat the disease with improved efficacy compared to eye drops, and also exploring safety of the drug eluding contact lens in an animal model. Our goal is to design a lens that is safe and that can deliver a daily therapeutic dose of cysteamine to the cornea while retaining drug stability. We show that cysteamine diffuses out rapidly from all lenses due to its small size. Vitamin E incorporation increases the release duration of both ACUVUE®OASYS® and ACUVUE® TruEyeTM but the effect is more pronounced in TruEyeTM likely due to the low solubility of vitamin E in the lens matrix and higher aspect ratio of the barriers. The barriers are not effective in hydrogel lenses, which along with the high aspect ratio in silicone hydrogels suggests that barriers could be forming at the interface of the silicone and hydrogel phases. The presence of vitamin E has an additional beneficial effect of reduction in the oxidation rates, likely due to a transport barrier between the oxygen diffusing through the silicone channels and drug located in the hydrogel phase. Based on this study, both Acuvue®OASYS® and ACUVUE® TruEyeTM can be loaded with vitamin E to design a cysteamine eluting contact lenses for effective therapy of cystinosis. The lenses must be worn for about 4–5 hr. each day, which is less than the typical duration of daily‐wear. The vitamin E and cysteamine loaded lenses did not exhibit any toxicity in a rabbit model over a period of 7‐days.