Dataset Information

3D Printable, Modified Trephine Designs for Consistent Anterior Lamellar Keratectomy Wounds in Rabbits.

ABSTRACT:

Purpose

Our goal is to develop a low-cost tool that can be used to create consistent, partial-thickness defects in rabbit and other large animals with minimal surgical training and that can facilitate pre-clinical testing of lamellar and in situ-forming biosynthetic matrix materials for corneal repair.

Materials & methods

In this study, three modified trephines were designed to create deep corneal wound defects with consistent depth in large animals. The modified trephines incorporated either 3D-printed parts made from photopolymerizable resins, or custom-cut commercially available Teflon sheets. Wound defects were imaged with optical coherence tomography (OCT), and the depth was analyzed based on the OCT images.

Results

The results revealed that an inner-stopper guard trephine had the best performance in creating consistent and precise wound defect depth compared to modified vacuum trephine and custom guard vacuum trephine. A 75% ± 10% cut of the cornea was achieved with the inner-stopper guard trephine. The wound defect depth by created by the inner-stopper guard trephine was independent of the corneal thickness or size of the globes. Although the cut depth of the inner-stopper guard trephine differed by the experience-level of its users, the consistency (standard deviation) of the depth was independent of experience.

Conclusions

Our studies provided three cost-efficient animal trephines that can create corneal wounds of consistent depth by lab researchers without extensive training in keratectomy.

SUBMITTER: Chen F

PROVIDER: S-EPMC8483018 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature

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Publications

3D Printable, Modified Trephine Designs for Consistent Anterior Lamellar Keratectomy Wounds in Rabbits.

Chen Fang F Buickians David D Le Peter P Xia Xin X Montague-Alamin Spencer Q SQ Blanco Varela Ignacio Blanco IB Mundy David C DC Logan Caitlin M CM Myung David D

Current eye research 20210121 8

<h4>Purpose</h4>Our goal is to develop a low-cost tool that can be used to create consistent, partial-thickness defects in rabbit and other large animals with minimal surgical training and that can facilitate pre-clinical testing of lamellar and in situ-forming biosynthetic matrix materials for corneal repair.<h4>Materials & methods</h4>In this study, three modified trephines were designed to create deep corneal wound defects with consistent depth in large animals. The modified trephines incorpo ...[more]

PMID: 33474996

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Project description:Extracellular matrix (ECM) supplies both physical and chemical signals to keratocytes which can impact their differentiation to fibroblasts and/or myofibroblasts. It also provides a substrate through which they migrate during wound repair. We have previously shown that following transcorneal freeze injury (FI), migrating corneal fibroblasts align parallel to the stromal lamellae during wound repopulation. In this study, we compare cell and ECM patterning both within and on top of the stroma at different time points following lamellar keratectomy (LK) in the rabbit. Twelve rabbits received LK in one eye. Rabbits were monitored using in vivo confocal microscopy at 3, 7, 21 and 60 days after injury. A subset of animals was sacrificed at each time point to further investigate cell and matrix patterning. Tissue was fixed and labeled in situ with Alexa Fluor 488 phalloidin (for F-actin), and imaged using multiphoton fluorescence and second harmonic generation (SHG) imaging (for collagen). Immediately following LK, cell death occurred in the corneal stroma directly beneath the injury. At 7 and 21 days after LK, analysis of fluorescence (F-actin) and SHG results (collagen) indicated that fibroblasts were co-aligned with the collagen lamellae within this region. In contrast, stromal cells accumulating on top of the stromal wound bed were randomly arranged, contained more prominent stress fibers, and expressed alpha smooth muscle actin (α-SMA) and fibronectin. At 60 days, cells and matrix in this region had become co-aligned into lamellar-like structures; cells were elongated but did not express stress fibers. Corneal haze measured using in vivo confocal microscopy peaked at 21 days after LK, and was significantly reduced by 60 days. Cell morphology and patterning observed in vivo was similar to that observed in situ. Our results suggest that the topography and alignment of the collagen lamellae direct fibroblast patterning during repopulation of the native stroma after LK injury in the rabbit. In contrast, stromal cells accumulating on top of the stromal wound bed initially align randomly and produce a fibrotic ECM. Remarkably, over time, these cells appear to remodel the ECM to produce a lamellar structure that is similar to the native corneal stroma.

Project description:PurposeTo evaluate wound healing in rabbit corneas that developed a spontaneous persistent epithelial defect (PED) after photorefractive keratectomy (PRK).MethodsForty-eight 10- to 15-week-old female New Zealand White rabbits weighing 2.5 to 3.0 kg underwent either -3 diopter (D) or -9 D PRK to generate a series of corneas to study wound healing after injury. During that series, seven corneas developed a PED detected with 1% fluorescein staining at a slit lamp that either did not have epithelial closure by 1 week after surgery or subsequently had the closed epithelium break down to form a PED 2 to 3 weeks after surgery. The corneas had slit-lamp photography, with and without 1% fluorescein, and were removed from the normal PRK series. Each PED cornea was evaluated using immunohistochemistry for the myofibroblast marker α-smooth muscle actin (α-SMA), keratocyte marker keratocan, and mesenchymal cell marker vimentin, as well as basement membrane components perlecan and collagen type IV.ResultsAll seven corneas that had PRK with a PED, even the two evaluated at only 1 week after PRK, had α-SMA-positive myofibroblasts populating the anterior stroma within the PED, along with comingled α-SMA-negative cells that were likely corneal fibroblasts and possibly bone marrow-derived fibrocytes. Both perlecan and collagen type IV accumulated in the anterior stroma of the epithelial defects without an epithelial basement membrane, likely produced by corneal fibroblasts to modulate transforming growth factor-β entering the stroma from the tears and peripheral epithelium.ConclusionsCorneas with a PED that occurred following PRK (a procedure that produces a transient neurotropic state in the cornea) had myofibroblasts populating the superficial stroma within the epithelial defect as early as 1 week after the surgery.Translational relevancePharmacologic treatments that trigger myofibroblast apoptosis, including topical losartan, could facilitate decreased scarring fibrosis in corneas with a PED.

Project description:IntroductionClinical trial designs based on the assumption of independent observations are well established. Clustered clinical trial designs, where all observational units belong to a cluster and outcomes within clusters are expected to be correlated, have also received considerable attention. However, many clinical trials involve partially clustered data, where only some observational units belong to a cluster. Examples of such trials occur in neonatology, where participants include infants from both singleton and multiple births, and ophthalmology, where one or two eyes per participant may need treatment. Partial clustering can also arise in trials of group-based treatments (e.g. group education or counselling sessions) or treatments administered individually by a discrete number of health care professionals (e.g. surgeons or physical therapists), when this is compared to an unclustered control arm. Trials involving partially clustered data have received limited attention in the literature and the current lack of standardised terminology may be hampering the development and dissemination of methods for designing and analysing these trials.Methods and examplesIn this article, we present an overarching definition of partially clustered trials, bringing together several existing trial designs including those for group-based treatments, clustering due to facilitator effects and the re-randomisation design. We define and describe four types of partially clustered trial designs, characterised by whether the clustering occurs pre-randomisation or post-randomisation and, in the case of pre-randomisation clustering, by the method of randomisation that is used for the clustered observations (individual randomisation, cluster randomisation or balanced randomisation within clusters). Real life examples are provided to highlight the occurrence of partially clustered trials across a variety of fields. To assess how partially clustered trials are currently reported, we review published reports of partially clustered trials.DiscussionOur findings demonstrate that the description of these trials is often incomplete and the terminology used to describe the trial designs is inconsistent, restricting the ability to identify these trials in the literature. By adopting the definitions and terminology presented in this article, the reporting of partially clustered trials can be substantially improved, and we present several recommendations for reporting these trial designs in practice. Greater awareness of partially clustered trials will facilitate more methodological research into their design and analysis, ultimately improving the quality of these trials.

Dataset Information

3D Printable, Modified Trephine Designs for Consistent Anterior Lamellar Keratectomy Wounds in Rabbits.

Purpose

Materials & methods

Results

Conclusions

Publications

3D Printable, Modified Trephine Designs for Consistent Anterior Lamellar Keratectomy Wounds in Rabbits.

Similar Datasets

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