scholarly journals Tissue Equivalents: Template Curvature Influences Cell Alignment to Create Improved Human Corneal Tissue Equivalents (Adv. Biosys. 12/2017)

2017 ◽  
Vol 1 (12) ◽  
pp. 1770098
Author(s):  
Ricardo M. Gouveia ◽  
Elena Koudouna ◽  
James Jester ◽  
Francisco Figueiredo ◽  
Che J. Connon
Keyword(s):  
Corneal Tissue ◽  
Cell Alignment ◽  
Tissue Equivalents

scholarly journals Template Curvature Influences Cell Alignment to Create Improved Human Corneal Tissue Equivalents

2017 ◽  
Vol 1 (12) ◽  
pp. 1700135 ◽  
Author(s):  
Ricardo M. Gouveia ◽  
Elena Koudouna ◽  
James Jester ◽  
Francisco Figueiredo ◽  
Che J. Connon
Keyword(s):  
Corneal Tissue ◽  
Cell Alignment ◽  
Tissue Equivalents

An Anisotropic Biphasic Theory of Tissue-Equivalent Mechanics: The Interplay Among Cell Traction, Fibrillar Network Deformation, Fibril Alignment, and Cell Contact Guidance

1997 ◽  
Vol 119 (2) ◽  
pp. 137-145 ◽  
Author(s):  
V. H. Barocas ◽  
R. T. Tranquillo
Keyword(s):  
Contact Guidance ◽  
Deformation Tensor ◽  
Cell Contact ◽  
Cell Alignment ◽  
Collagen Gels ◽  
Cell Orientation ◽  
Collagen Network ◽  
Orientation Tensor ◽  
Tissue Equivalents ◽  
Cell Traction

We present a general mathematical theory for the mechanical interplay in tissue-equivalents (cell-populated collagen gels): Cell traction leads to compaction of the fibrillar collagen network, which for certain conditions such as a mechanical constraint or inhomogeneous cell distribution, can result in inhomogeneous compaction and consequently fibril alignment, leading to cell contact guidance, which affects the subsequent compaction. The theory accounts for the intrinsically biphasic nature of collagen gel, which is comprised of collagen network and interstitial solution. The theory also accounts for fibril alignment due to inhomogeneous network deformation, that is, anisotropic strain, and for cell alignment in response to fibril alignment. Cell alignment results in anisotropic migration and traction, as modeled by a cell orientation tensor that is a function of a fiber orientation tensor, which is defined by the network deformation tensor. Models for a variety of tissue-equivalents are shown to predict qualitatively the alignment that arises due to inhomogeneous compaction driven by cell traction.

Biological cell alignment for electrofusion

1992 ◽  
Vol 139 (3) ◽  
pp. 112
Author(s):  
S.J. MacDonald ◽  
P.S. Bodger ◽  
P.A. Elder
Keyword(s):  
Biological Cell ◽  
Cell Alignment

Assessment of Commercial Off-the-Shelf Tissue Adhesives for Sealing Military-Relevant Corneal Perforation Injuries

2021 ◽  
Author(s):  
Eric J Snider ◽  
Lauren E Cornell ◽  
Brandon M Gross ◽  
David O Zamora ◽  
Emily N Boice
Keyword(s):  
Intraocular Pressure ◽  
High Speed ◽  
Anterior Segment ◽  
Ocular Tissue ◽  
Corneal Tissue ◽  
Corneal Perforation ◽  
Tissue Adhesives ◽  
Open Globe ◽  
Wide Range ◽  
Commercial Off The Shelf

ABSTRACT Introduction Open-globe ocular injuries have increased in frequency in recent combat operations due to increased use of explosive weaponry. Unfortunately, open-globe injuries have one of the worst visual outcomes for the injured warfighter, often resulting in permanent loss of vision. To improve visual recovery, injuries need to be stabilized quickly following trauma, in order to restore intraocular pressure and create a watertight seal. Here, we assess four off-the-shelf (OTS), commercially available tissue adhesives for their ability to seal military-relevant corneal perforation injuries (CPIs). Materials and Methods Adhesives were assessed using an anterior segment inflation platform and a previously developed high-speed benchtop corneal puncture model, to create injuries in porcine eyes. After injury, adhesives were applied and injury stabilization was assessed by measuring outflow rate, ocular compliance, and burst pressure, followed by histological analysis. Results Tegaderm dressings and Dermabond skin adhesive most successfully sealed injuries in preliminary testing. Across a range of injury sizes and shapes, Tegaderm performed well in smaller injury sizes, less than 2 mm in diameter, but inadequately sealed large or complex injuries. Dermabond created a watertight seal capable of maintaining ocular tissue at physiological intraocular pressure for almost all injury shapes and sizes. However, application of the adhesive was inconsistent. Histologically, after removal of the Dermabond skin adhesive, the corneal epithelium was removed and oftentimes the epithelium surface penetrated into the wound and was adhered to inner stromal tissue. Conclusions Dermabond can stabilize a wide range of CPIs; however, application is variable, which may adversely impact the corneal tissue. Without addressing these limitations, no OTS adhesive tested herein can be directly translated to CPIs. This highlights the need for development of a biomaterial product to stabilize these injuries without causing ocular damage upon removal, thus improving the poor vision prognosis for the injured warfighter.

Use of Polycaprolactone in Corneal Tissue Engineering: A Review

2021 ◽  
pp. 102402
Author(s):  
Amin Orash Mahmoud Salehi ◽  
Saeed Heidari Keshel ◽  
Farshid Sefat ◽  
Lobat Tayebi
Keyword(s):  
Tissue Engineering ◽  
Corneal Tissue

scholarly journals Optimization of Collagen Chemical Crosslinking to Restore Biocompatibility of Tissue-Engineered Scaffolds

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 832
Author(s):  
Mohammad Mirazul Islam ◽  
Dina B. AbuSamra ◽  
Alexandru Chivu ◽  
Pablo Argüeso ◽  
Claes H. Dohlman ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Crosslinking Agent ◽  
Collagen Scaffold ◽  
Human Monocyte ◽  
Subsequent Treatment ◽  
Sodium Metabisulfite ◽  
Corneal Tissue ◽  
Dependent Manner ◽  
Collagen Scaffolds ◽  
Enzymatic Stability

Collagen scaffolds, one of the most used biomaterials in corneal tissue engineering, are frequently crosslinked to improve mechanical properties, enzyme tolerance, and thermal stability. Crosslinkers such as 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) are compatible with tissues but provide low crosslinking density and reduced mechanical properties. Conversely, crosslinkers such as glutaraldehyde (GTA) can generate mechanically more robust scaffolds; however, they can also induce greater toxicity. Herein, we evaluated the effectivity of double-crosslinking with both EDC and GTA together with the capability of sodium metabisulfite (SM) and sodium borohydride (SB) to neutralize the toxicity and restore biocompatibility after crosslinking. The EDC-crosslinked collagen scaffolds were treated with different concentrations of GTA. To neutralize the free unreacted aldehyde groups, scaffolds were treated with SM or SB. The chemistry involved in these reactions together with the mechanical and functional properties of the collagen scaffolds was evaluated. The viability of the cells grown on the scaffolds was studied using different corneal cell types. The effect of each type of scaffold treatment on human monocyte differentiation was evaluated. One-way ANOVA was used for statistical analysis. The addition of GTA as a double-crosslinking agent significantly improved the mechanical properties and enzymatic stability of the EDC crosslinked collagen scaffold. GTA decreased cell biocompatibility but this effect was reversed by treatment with SB or SM. These agents did not affect the mechanical properties, enzymatic stability, or transparency of the double-crosslinked scaffold. Contact of monocytes with the different scaffolds did not trigger their differentiation into activated macrophages. Our results demonstrate that GTA improves the mechanical properties of EDC crosslinked scaffolds in a dose-dependent manner, and that subsequent treatment with SB or SM partially restores biocompatibility. This novel manufacturing approach would facilitate the translation of collagen-based artificial corneas to the clinical setting.

scholarly journals Bio-Distribution and Pharmacokinetics of Topically Administered γ-Cyclodextrin Based Eye Drops in Rabbits

2021 ◽  
Vol 14 (5) ◽  
pp. 480
Author(s):  
Martin Kallab ◽  
Kornelia Schuetzenberger ◽  
Nikolaus Hommer ◽  
Bhavapriya Jasmin Schäfer ◽  
Doreen Schmidl ◽  
...  
Keyword(s):  
Single Dose ◽  
Drug Concentration ◽  
Vitreous Humor ◽  
Controlled Study ◽  
Eye Drops ◽  
Corneal Tissue ◽  
Single Administration ◽  
Local Tolerability ◽  
Dose Administration ◽  
Retinal Tissue

The purpose of this study was to evaluate the ocular pharmacokinetics, bio-distribution and local tolerability of γ-cyclodextrin (γCD) based irbesartan 1.5% eye drops and candesartan 0.15% eye drops after single and multiple topical administration in rabbit eyes. In this randomized, controlled study, a total number of 59 New Zealand White albino rabbits were consecutively assigned to two study groups. Group 1 (n = 31) received irbesartan 1.5% and group 2 (n = 28) candesartan 0.15% eye drops. In both groups, single dose and multiple administration pharmacokinetic studies were performed. Rabbits were euthanized at five predefined time points after single-dose administration, whereas multiple-dose animals were dosed for 5 days twice-daily and then euthanized 1 h after the last dose administration. Drug concentration was measured by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the retinal tissue, vitreous humor, aqueous humor, corneal tissue and in venous blood samples. Pharmacokinetic parameters including maximal drug concentration (Cmax), time of maximal drug concentration (Tmax), half-life and AUC were calculated. To assess local tolerability, six additional rabbits received 1.5% irbesartan eye drops twice daily in one eye for 28 days. Tolerability was assessed using a modified Draize test and corneal sensibility by Cochet Bonnet esthesiometry. Both γCD based eye drops were rapidly absorbed and distributed in the anterior and posterior ocular tissues. Within 0.5 h after single administration, the Cmax of irbesartan and candesartan in retinal tissue was 251 ± 142 ng/g and 63 ± 39 ng/g, respectively. In the vitreous humor, a Cmax of 14 ± 16 ng/g for irbesartan was reached 0.5 h after instillation while Cmax was below 2 ng/g for candesartan. For multiple dosing, the observed Cmean in retinal tissue was 338 ± 124 ng/g for irbesartan and 36 ± 10 ng/g for candesartan, whereas mean vitreous humor concentrations were 13 ± 5 ng/g and <2 ng/g, respectively. The highest plasma concentrations of both irbesartan (Cmax 5.64 ± 4.08 ng/mL) and candesartan (Cmax 4.32 ± 1.04 ng/mL) were reached 0.5 h (Tmax) after single administration. Local tolerability was favorable with no remarkable differences between the treated and the control eyes. These results indicate that irbesartan and candesartan in γCD based nanoparticle eye drops can be delivered to the retinal tissue of the rabbit’s eye in pharmacologically relevant concentrations. Moreover, safety and tolerability profiles appear to be favorable in the rabbit animal model.

scholarly journals Characterization of Ocular Surface Microbial Profiles Revealed Discrepancies between Conjunctival and Corneal Microbiota

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 405
Author(s):  
Anna Matysiak ◽  
Michal Kabza ◽  
Justyna A. Karolak ◽  
Marcelina M. Jaworska ◽  
Malgorzata Rydzanicz ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Ocular Surface ◽  
Molecular Techniques ◽  
Corneal Tissue ◽  
Rna Seq ◽  
Microbiome Composition ◽  
Viral Sequences ◽  
Pcr Techniques ◽  
Unmapped Reads

The ocular microbiome composition has only been partially characterized. Here, we used RNA-sequencing (RNA-Seq) data to assess microbial diversity in human corneal tissue. Additionally, conjunctival swab samples were examined to characterize ocular surface microbiota. Short RNA-Seq reads, obtained from a previous transcriptome study of 50 corneal tissues, were mapped to the human reference genome GRCh38 to remove sequences of human origin. The unmapped reads were then used for taxonomic classification by comparing them with known bacterial, archaeal, and viral sequences from public databases. The components of microbial communities were identified and characterized using both conventional microbiology and polymerase chain reaction (PCR) techniques in 36 conjunctival swabs. The majority of ocular samples examined by conventional and molecular techniques showed very similar microbial taxonomic profiles, with most of the microorganisms being classified into Proteobacteria, Firmicutes, and Actinobacteria phyla. Only 50% of conjunctival samples exhibited bacterial growth. The PCR detection provided a broader overview of positive results for conjunctival materials. The RNA-Seq assessment revealed significant variability of the corneal microbial communities, including fastidious bacteria and viruses. The use of the combined techniques allowed for a comprehensive characterization of the eye microbiome’s elements, especially in aspects of microbiota diversity.

Gamma-Irradiated Cornea in Combat-related Ocular Trauma

2020 ◽  
Author(s):  
Brian M Davis ◽  
Carson Clabeaux ◽  
Anton Vlasov ◽  
Paul Houghtaling
Keyword(s):  
Ocular Trauma ◽  
Cost Savings ◽  
Corneal Tissue ◽  
Significant Cost ◽  
Visual Rehabilitation ◽  
Military Health ◽  
Corneal Injury ◽  
Gamma Irradiated ◽  
The Military ◽  
Penetrating Ocular Trauma

ABSTRACT Corneal injury is a known risk for deployed troops worldwide. To the authors’ knowledge, there has been no reported use of gamma-irradiated corneas in the setting of severe corneal trauma. Our report highlights the case of a 36-year-old active duty solider who sustained bilateral penetrating ocular trauma from a nearby ordnance explosion. We propose that ocular surgeons should consider utilizing gamma-irradiated corneas in (1) a situation where the corneal tissue is so damaged that it would be challenging to accomplish an adequate repair while providing the opportunity for future visual rehabilitation and (2) remote and/or deployed environments where storage of fresh donor tissue is limited. The long shelf life of gamma-irradiated corneas reduces the need for specialized storage equipment and the need for continuous resupply, both potentially leading to significant cost savings for the Military Health System.

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