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Biocompatibility and biodegradation studies of subconjunctival implants in rabbit eyes.

Peng Y, Ang M, Foo S, Lee WS, Ma Z, Venkatraman SS, Wong TT - PLoS ONE (2011)

Bottom Line: PLC70/30 15±0.6%; P = 0.91) over a period of 6 months.Histology, immunohistochemistry and immuno-fluorescence also revealed no significant inflammatory reaction from either of the microfilms, which confirmed that both microfilms are biocompatible.The duration of the drug delivery can be tailored by selecting the materials, which have different degradation kinetics, to suit the desired clinical therapeutic application.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore.

ABSTRACT
Sustained ocular drug delivery is difficult to achieve. Most drugs have poor penetration due to the multiple physiological barriers of the eye and are rapidly cleared if applied topically. Biodegradable subconjunctival implants with controlled drug release may circumvent these two problems. In our study, two microfilms (poly [d,l-lactide-co-glycolide] PLGA and poly[d,l-lactide-co-caprolactone] PLC were developed and evaluated for their degradation behavior in vitro and in vivo. We also evaluated the biocompatibility of both microfilms. Eighteen eyes (9 rabbits) were surgically implanted with one type of microfilm in each eye. Serial anterior-segment optical coherence tomography (AS-OCT) scans together with serial slit-lamp microscopy allowed us to measure thickness and cross-sectional area of the microfilms. In vitro studies revealed bulk degradation kinetics for both microfilms, while in vivo studies demonstrated surface erosion kinetics. Serial slit-lamp microscopy revealed no significant inflammation or vascularization in both types of implants (mean increase in vascularity grade PLGA50/50 12±0.5% vs. PLC70/30 15±0.6%; P = 0.91) over a period of 6 months. Histology, immunohistochemistry and immuno-fluorescence also revealed no significant inflammatory reaction from either of the microfilms, which confirmed that both microfilms are biocompatible. The duration of the drug delivery can be tailored by selecting the materials, which have different degradation kinetics, to suit the desired clinical therapeutic application.

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Photographs with fluorescence microscopy of sections of PLGA50/50 and PLC70/30 with immunofluorescence stains for T cells.A, B: 1– Section of eye implanted with PLGA50/50 microfilm at 3 and 6 months respectively. A, B: 2 – Section of eye implanted with PLC70/30 microfilm at 3 and 6 months respectively.
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pone-0022507-g011: Photographs with fluorescence microscopy of sections of PLGA50/50 and PLC70/30 with immunofluorescence stains for T cells.A, B: 1– Section of eye implanted with PLGA50/50 microfilm at 3 and 6 months respectively. A, B: 2 – Section of eye implanted with PLC70/30 microfilm at 3 and 6 months respectively.

Mentions: Sections stained with immunofluorescence for CD45 T cells were analyzed for both PLC70/30 and PLGA50/50 at 3 and 6 months. There was minimal inflammatory reaction, with scattered T cells surrounding both implants. We also noted a reduction in T cells surrounding the implant for both PLGA50/50 and PLC70/30 when comparing implants at 3 and 6 months post-operatively (Figure 11).


Biocompatibility and biodegradation studies of subconjunctival implants in rabbit eyes.

Peng Y, Ang M, Foo S, Lee WS, Ma Z, Venkatraman SS, Wong TT - PLoS ONE (2011)

Photographs with fluorescence microscopy of sections of PLGA50/50 and PLC70/30 with immunofluorescence stains for T cells.A, B: 1– Section of eye implanted with PLGA50/50 microfilm at 3 and 6 months respectively. A, B: 2 – Section of eye implanted with PLC70/30 microfilm at 3 and 6 months respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3142149&req=5

pone-0022507-g011: Photographs with fluorescence microscopy of sections of PLGA50/50 and PLC70/30 with immunofluorescence stains for T cells.A, B: 1– Section of eye implanted with PLGA50/50 microfilm at 3 and 6 months respectively. A, B: 2 – Section of eye implanted with PLC70/30 microfilm at 3 and 6 months respectively.
Mentions: Sections stained with immunofluorescence for CD45 T cells were analyzed for both PLC70/30 and PLGA50/50 at 3 and 6 months. There was minimal inflammatory reaction, with scattered T cells surrounding both implants. We also noted a reduction in T cells surrounding the implant for both PLGA50/50 and PLC70/30 when comparing implants at 3 and 6 months post-operatively (Figure 11).

Bottom Line: PLC70/30 15±0.6%; P = 0.91) over a period of 6 months.Histology, immunohistochemistry and immuno-fluorescence also revealed no significant inflammatory reaction from either of the microfilms, which confirmed that both microfilms are biocompatible.The duration of the drug delivery can be tailored by selecting the materials, which have different degradation kinetics, to suit the desired clinical therapeutic application.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore.

ABSTRACT
Sustained ocular drug delivery is difficult to achieve. Most drugs have poor penetration due to the multiple physiological barriers of the eye and are rapidly cleared if applied topically. Biodegradable subconjunctival implants with controlled drug release may circumvent these two problems. In our study, two microfilms (poly [d,l-lactide-co-glycolide] PLGA and poly[d,l-lactide-co-caprolactone] PLC were developed and evaluated for their degradation behavior in vitro and in vivo. We also evaluated the biocompatibility of both microfilms. Eighteen eyes (9 rabbits) were surgically implanted with one type of microfilm in each eye. Serial anterior-segment optical coherence tomography (AS-OCT) scans together with serial slit-lamp microscopy allowed us to measure thickness and cross-sectional area of the microfilms. In vitro studies revealed bulk degradation kinetics for both microfilms, while in vivo studies demonstrated surface erosion kinetics. Serial slit-lamp microscopy revealed no significant inflammation or vascularization in both types of implants (mean increase in vascularity grade PLGA50/50 12±0.5% vs. PLC70/30 15±0.6%; P = 0.91) over a period of 6 months. Histology, immunohistochemistry and immuno-fluorescence also revealed no significant inflammatory reaction from either of the microfilms, which confirmed that both microfilms are biocompatible. The duration of the drug delivery can be tailored by selecting the materials, which have different degradation kinetics, to suit the desired clinical therapeutic application.

Show MeSH
Related in: MedlinePlus