1. Setup of Sterile Field
<ol>
	<li>Don proper attire including cap and mask. Wear eye protection when in the processing room.</li>
	<li>Prepare the processing area. When using a processing room, maintain continuous operation of the fan to create positive pressure in the room.</li>
	<li>Gather all supplies. Check expiration dates, package integrity, and sterilization indicator.</li>
	<li>Wash hands and don non-sterile gloves.</li>
	<li>Open the sterile kits to establish a sterile field. When using a processing room, place the kits on the table and aseptically open the wraps. Do not utilize the outer 1&#189; inches of the wrap as part of the sterile field as this segment is considered unsterile.</li>
	<li>Using aseptic technique, open and drop sterile items onto sterile field unless already part of the premade pack.</li>
	<li>Move microscope so that it is above the sterile field, turn on light source of microscope, and adjust oculars as necessary.</li>
	<li>Obtain corneal tissue to be stripped (in preservation media) and place next to the prepared sterile processing area. Loosen cap of viewing chamber and let it rest on top of viewing chamber base with no threads engaged. Discard non-sterile gloves.</li>
	<li>Open one pair of sterile gloves and sterile gown with towel.</li>
	<li>Perform surgical scrub. Put on sterile gown, then sterile gloves.</li>
	<li>Open instrument boxes so that all supplies are accessible. Open moisture impermeable drape to create the work area.</li>
	<li>Attach needle to a 5 cc syringe. Using a hemostat, prepare the 30 G needle by placing a bend 1 mm from the bevel, and another bend 1 mm from the base (to form an &#8220;S&#8221; shape).</li>
	<li>Assemble the glass syringe for the trypan blue stain by placing the plunger into the syringe and finger tightening the plunger. Attach cannula.</li>
	<li>Attach the cannula to the balanced salt solution (BSS) bottle.</li>
	<li>Separate the trephine punch from the vacuum block and set aside. Center the vacuum block within the field of view of the microscope.</li>
	<li>Bring the vacuum block into focus by adjusting the microscope settings.</li>
</ol>
2. Procedure for Donor Tissue Preparation
<ol>
	<li>Lift lid of viewing chamber using foil square as a barrier. With opposite hand and using forceps, gently grasp cornea by sclera rim to remove cornea. Replace lid of viewing chamber.</li>
	<li>Completely depress the suction syringe, then place cornea epithelial side down on the vacuum block and ensure that it is centered. (Figure 1)</li>
	<li>Gently lower seating ring on to the vacuum block using the guide posts. Engage vacuum by slowly releasing piston of the suction syringe. Remove the seating ring and set aside. (Figure 2).</li>
	<li>Perform a partial trephination to score through the Descemet&#8217;s membrane.</li>
	<li>Adjust microscope zoom and focus so that the tissue is well visualized.</li>
	<li>Tilt the vacuum block and use a sterile swab spear placed at the limbus to remove excess medium. (Figure 3)</li>
	<li>Place enough stain at the limbus to stain the edge of the scored Descemet&#8217;s membrane. Allow the stain to remain on the endothelium for 60-90 sec. (Figure 4)</li>
	<li>Remove stain:
	<ol>
		<li>Tilt the vacuum block to pour the stain off of the cornea and onto gauze pad.</li>
		<li>Use the surgical spears to remove excess stain from the limbal area of the cornea, taking care not to touch the endothelium. (Figure 5)</li>
	</ol>
	</li>
	<li>Use several drops of BSS to rinse the cornea of staining solution, and sterile swab spears to remove excess BSS. (Figure 6)</li>
	<li>Place 1-2 drops of BSS on the sclera rim to prevent tissue from drying. Repeat as necessary throughout the procedure.</li>
	<li>Perform partial dissection of Descemet&#8217;s membrane:
	<ol>
		<li>Beginning where the tubing connects to the vacuum block, using open forceps, place one tip at the edge of the score mark and gently separate Descemet&#8217;s membrane and endothelium away from the stroma. (Figure 7).</li>
		<li>Separate Descemet&#8217;s membrane and endothelium not more than 1 mm from the scored edge and continue dissection 360&#176; around. (Figure 8).</li>
		<li>Note location of any micro tears by placing a dot on the vacuum block with the skin marker. 
		NOTE: If the trephine did not penetrate completely through Descemet&#8217;s membrane, use the beveled edge of the prepared 30 G needle to complete the score through Descemet&#8217;s membrane where necessary, followed by a second application of staining as needed. If Descemet&#8217;s membrane&#8217;s adhesiveness is impeding the partial dissection, remove the endothelium outside the trephinated area as needed.</li>
	</ol>
	</li>
	<li>Use forceps to remove any endothelial tags that overlap the score mark.</li>
	<li>Consider the location of previously marked micro tears and rotate the vacuum block so that the largest is at 6 o&#8217;clock. This will become the hinge of the flap.</li>
	<li>Using the forceps, grasp the Descemet&#8217;s membrane at 12 o&#8217;clock. Gently separate the Descemet&#8217;s membrane from the stroma by peeling towards the hinge. Create the hinge by stopping the separation 2 mm from the score mark. 
	NOTE: Peripheral edges of flap will begin to scroll during separation. (Figure 9).</li>
	<li>Gently lay the flap back in place on the stroma. Use BSS and swab spears to unscroll the endothelium and return it to its original position. (Figure 10A-C)</li>
	<li>Remove residual fluid from between Descemet&#8217;s membrane and stroma with sterile swab spears so the flap stays in position. (Figure 11)</li>
	<li>Use sterile swab spears to soak up any excess moisture from the sclera near the hinge. Use the skin marker to draw an arrowhead on the sclera rim pointing to the center of the hinge, remove any excess ink using a sterile swab spear. (Figure 12)</li>
	<li>Release vacuum by depressing the piston of the syringe connected to the vacuum block. While vacuum is disengaged, use forceps to remove cornea from the vacuum block.</li>
	<li>Lift lid of viewing chamber using foil square as a barrier. Place the cornea in the viewing chamber, endothelial side up, and replace lid of viewing chamber.</li>
	<li>Repeat above procedure steps with mate cornea, if applicable. Use gauze to clean the vacuum block before processing the second tissue.</li>
	<li>Tighten the viewing chamber lid(s) and remove tissue from the processing area.</li>
	<li>Break down the sterile field by disposing of items according to Biohazardous Waste Management Plan. Remove contaminated gloves, and gown. Wash hands and don non-sterile gloves.</li>
	<li>Perform post-cut slit lamp evaluation and specular microscopy of the cornea(s) and record the findings.</li>
</ol>

<ol>
	<li>Fernandez, M., Afshari, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelial+Keratoplasty:+From+DLEK+to+DMEK.">Endothelial Keratoplasty: From DLEK to DMEK.</a> Middle East African Journal of Ophthalmology. 17 (1), 5-8 (2010).</li><li>Kruse, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Stepwise+Approach+to+Donor+Preparation+and+Insertion+Increases+Safety+and+Outcome+of+Descemet+Membrane+Endothelial+Keratoplasty.">A Stepwise Approach to Donor Preparation and Insertion Increases Safety and Outcome of Descemet Membrane Endothelial Keratoplasty.</a> Cornea. 30 (5), 580-587 (2011).</li><li>Dapena, I., Moutsouris, K., Droutsas, K., Ham, L., van Dijk, K., Melles, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standardized+'No-Touch'+Technique+for+Descemet+Membrane+Endothelial+Keratoplasty.">Standardized 'No-Touch' Technique for Descemet Membrane Endothelial Keratoplasty.</a> Archives of Ophthalmology. 129, 88-94 (2011).</li><li>Tourtas, T., Laaser, K., Bachmann, B., Cursiefen, C., Kruse, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Descemet+Membrane+Endothelial+Keratoplasty+versus+Descemet+Stripping+Automated+Endothelial+Keratoplasty.">Descemet Membrane Endothelial Keratoplasty versus Descemet Stripping Automated Endothelial Keratoplasty.</a> American Journal of Ophthalmology. 153 (6), 1082-1090 (2012).</li><li>Guerra, F., Anshu, A., Price, M., Price, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelial+Keratoplasty:+fellow+eyes+comparison+of+Descemet+stripping+automated+endothelial+keratoplasty+and+Descemet+membrane+endothelial+keratoplasty.">Endothelial Keratoplasty: fellow eyes comparison of Descemet stripping automated endothelial keratoplasty and Descemet membrane endothelial keratoplasty.</a> Cornea. 30 (12), 1382-1386 (2011).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> 2012 Eye Banking Statistical Report: Surgical Use and Indications for Corneal Transplant Statistical Report Analysis. , (2012).</li><li>Price, M., Price, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Descemet's+stripping+endothelial+keratoplasty.">Descemet's stripping endothelial keratoplasty.</a> Current Opinion Ophthalmology. 18 (4), 290-294 (2007).</li><li>Woodward, M., Titus, M., Mavin, K., Shtein, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Corneal+Donor+Tissue+Preparation+for+Endothelial+Keratoplasty.">Corneal Donor Tissue Preparation for Endothelial Keratoplasty.</a> Journal of Visualized Experiments. (64), e3847 (2012).</li><li>Price, M., Price, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Descemet's+membrane+endothelial+keratoplasty+surgery:+update+on+the+evidence+and+hurdles+to+acceptance.">Descemet's membrane endothelial keratoplasty surgery: update on the evidence and hurdles to acceptance.</a> Current Opinion Ophthalmology. 24 (4), 329-335 (2013).</li><li>Venzano, D., Pagani, P., Randazzo, N., Cabiddu, F., Traverrso, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Descemet+Membrane+air-bubble+separation+in+donor+cornea.">Descemet Membrane air-bubble separation in donor cornea.</a> Journal of Cataract and Refractive Surgery. 36 (12), 2022-2027 (2010).</li><li>Price, F., Price, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> DSEK: What you need to know about endothelial keratoplasty. , (2009).</li><li>Studeny, P., Sivekova, D., Lieheova, K., Vokrojova, M., Kuchynka, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hybrid+technique+of+lamellar+keratoplasty+(DMEK-S).">Hybrid technique of lamellar keratoplasty (DMEK-S).</a> Journal of Ophthalmology. 2013, 2013.254383 (2013).</li><li>Muraine, M., Gueudry, J., He, Z., Piselli, S., Lefevre, S., Toubeau, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+technique+for+the+preparation+of+corneal+grafts+for+Descemet+membrane+endothelial+keratoplasty.">Novel technique for the preparation of corneal grafts for Descemet membrane endothelial keratoplasty.</a> American Journal of Ophthalmology. 156 (5), 851-859 (2013).</li><li>Lie, J. T., Birbal, R., Ham, L., van der Wees, J., Melles, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Donor+tissue+preparation+for+Descemet+membrane+endothelial+keratoplasty.">Donor tissue preparation for Descemet membrane endothelial keratoplasty.</a> Journal of Cataract Refractive Surgery. 34 (9), 1578-1583 (2008).</li><li>Kruse, F. E., Laaser, K., Cursiefen, C., Heindl, L. M., Schlotzer-Schrehardt, U., Riss, S., Bachmann, B. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+stepwise+approach+to+donor+preparation+and+insertion+increases+safety+and+outcome+of+Descemet+membrane+endothelial+keratoplasty.">A stepwise approach to donor preparation and insertion increases safety and outcome of Descemet membrane endothelial keratoplasty.</a> Cornea. 30 (5), 580-587 (2011).</li><li>Rudolph, M., Kaaser, L., Bachmann, B., Cursiefen, C., Epstein, D., Kruse, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Corneal+higher-order+aberrations+after+Descemet&#8217;s+membrane+endothelial+keratoplasty.">Corneal higher-order aberrations after Descemet&#8217;s membrane endothelial keratoplasty.</a> Ophthalmology. 119 (3), 528-535 (2012).</li><li>Price, F., Price, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+endothelial+keratoplasty.">Evolution of endothelial keratoplasty.</a> Cornea. 32, 28-32 (2013).</li><li>Dapena, I., Dapena, L., Dirisamer, M., Ham, L., Melles, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visual+acuity+and+endothelial+cell+density+following+Descemet+membrane+endothelial+keratoplasty+(DMEK).">Visual acuity and endothelial cell density following Descemet membrane endothelial keratoplasty (DMEK).</a> Arch Soc Esp Oftalmol. 86 (12), 395-401 (2011).</li></ol>

Hassan Tausif and Dr. Navasuja Chandrasekaran have nothing to disclose. Drs. Mian, Shtein, and Woodward are medical directors for the Michigan Eye Bank. Mr. Mavin, Mr. Titus, and Ms. Johnson are employees of Midwest Eye Banks.

The corneal endothelial cell layer plays a critical role in maintaining corneal clarity through dehydration. Diseases of the endothelial cells can result in significant visual impairment. DMEK aims to replace the diseased endothelial cells with a donor graft consisting of Descemet&#8217;s membrane and endothelial cell layer. Donor tissue preparation with an intact DM and adequate endothelial cell count are critical to the survival of the graft tissue. Tearing of DM during donor tissue preparation can result in tissue los...

Endothelial Keratoplasty (EK) has rapidly replaced penetrating keratoplasty (PKP) as the procedure of choice for treatment of endothelial diseases accounting for over 50% of all transplants performed in the United States in 20126. PKP is limited by prolonged visual rehabilitation with high astigmatism and refractive instability, loss of globe integrity and suture-related complications. Early generation EK procedures, including Deep Lamellar Endothelial Keratoplasty (DLEK) involved manual dissection of corneal stroma with transplantation of partial thickness donor tissue. These procedures were successful in transplanting donor endothelial tissue while maintaining an intact corneal surface but were technically challenging and resulted in limited best corrected visual acuity due to an irregular corneal lamellar interface1. The current EK procedure of choice is Descemet&#8217;s Stripping Endothelial Keratoplasty (DSEK) which offers corneal clarity with faster recovery of vision, minimizes postoperative refractive error and astigmatism, and decreases risk of traumatic wound dehiscence while maintaining the corneal surface7. This procedure involves removal of the diseased Descemet&#39;s membrane and endothelium and replacement with partial thickness donor corneal tissue comprising a new endothelial cell layer. The donor cornea is dissected with a microkeratome to prepare the posterior tissue being transplanted8. Preparation of the donor tissue by the eye-banks has been instrumental in the rapid growth and, arguably, the success of this procedure. The near 16-fold increase in DSEK procedures in the United States between 2005 and 2012 corresponds with almost half of the tissue currently being prepared by the eye-banks6.
Although DSEK can improve visual acuity to 20/40 or better, most patients do not achieve 20/20 vision due to stromal interface haze and increased light scatter from the addition of donor stromal tissue7. The EK surgical technique has progressed to Descemet&#8217;s Membrane Endothelial Keratoplasty (DMEK) which involves transplantation of only donor Descemet&#39;s membrane (DM) and endothelium. This procedure has a higher proportion of patients who achieve 20/20 vision, faster visual recovery, and a lower risk of endothelial rejection9. However, preparation of donor tissue is more challenging due to the thinner graft dimensions.

<table border="0" cellpadding="0" cellspacing="0" width="770">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Name of Material/ Equipment</td>
			<td style="width:268px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">VisionBlue&#160;</td>
			<td style="width:268px;">D.O.R.C., Zuiland, The Netherlands</td>
			<td style="width:119px;">NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Barron vacuum punch</td>
			<td style="width:268px;">Katena, Denville, New Jersey</td>
			<td style="width:119px;">K20-2112</td>
			<td></td>
		</tr>
	</tbody>
</table>

corneal donor tissue preparation for descemet's membrane endothelial keratoplasty

Descemet&#8217;s Membrane Endothelial Keratoplasty (DMEK) is a form of corneal transplantation in which only a single cell layer, the corneal endothelium, along with its basement membrane (Descemet&#39;s membrane) is introduced onto the recipient&#39;s posterior stroma3. Unlike Descemet&#8217;s Stripping Automated Endothelial Keratoplasty (DSAEK), where additional donor stroma is introduced, no unnatural stroma-to-stroma interface is created. As a result, the natural anatomy of the cornea is preserved as much as possible allowing for improved recovery time and visual acuity4. Endothelial Keratoplasty (EK) is the procedure of choice for treatment of endothelial dysfunction. The advantages of EK include rapid recovery of vision, preservation of ocular integrity and minimal refractive change due to use of a small, peripheral incision1. DSAEK utilizes donor tissue prepared with partial thickness stroma and endothelium. The rapid success and utilization of this procedure can be attributed to availability of eye-bank prepared precut tissue. The benefits of eye-bank preparation of donor tissue include elimination of need for specialized equipment in the operating room and availability of back up donor tissue in case of tissue perforation during preparation. In addition, high volume preparation of donor tissue by eye-bank technicians may provide improved quality of donor tissue. DSAEK may have limited best corrected visual acuity due to creation of a stromal interface between the donor and recipient cornea. Elimination of this interface with transplantation of only donor Descemet&#39;s membrane and endothelium in DMEK may improve visual outcomes and reduce complications after EK5. Similar to DSAEK, long term success and acceptance of DMEK is dependent on ease of availability of precut, eye-bank prepared donor tissue. Here we present a stepwise approach to donor tissue preparation which may reduce some barriers eye-banks face in providing DMEK grafts.

Proper separation of DM and endothelium from stroma is essential in preparing precut tissue for DMEK. Fifty donor corneas with a mean age of 65 &#177; 6 years (range 55-75), death to processing time of 5.9 &#177; 2.3 days (range 1-10) and endothelial cell density (ECD) of 2,616 &#177; 321 cells/mm2 (range 2,049-3,247) were used to assess feasibility and reproducibility of the surgical preparation technique by two eye bank technicians. The success rate was 72% in the first 25 cases and increased to 80% in the s...

Watch this Scientific Journal Video about Corneal Donor Tissue Preparation for Descemet's Membrane Endothelial Keratoplasty at JoVE.com

Corneal Donor Tissue Preparation for Descemet&#039;s Membrane Endothelial Keratoplasty

Endothelial keratoplasty is a surgical technique continuously evolving as advancements result in transplantation of thinner grafts with each succession1. Here we present a technique for controlled manual tissue dissection to allow safe and repeatable separation of endothelium and Descemet&#39;s membranes from donor corneoscleral buttons for transplantation2.

Corneal Donor Tissue Preparation for Descemet's Membrane Endothelial Keratoplasty

Descemet&#8217;s Membrane Endothelial Keratoplasty (DMEK) is a form of corneal transplantation in which only a single cell layer, the corneal endothelium, ...

corneal-donor-tissue-preparation-for-descemet-s-membrane-endothelial

Research

JoVE Journal

Medicine

15.2K Views.  University of Michigan. Endothelial keratoplasty is a surgical technique continuously evolving as advancements result in transplantation of thinner grafts with each succession1. Here we present a technique for controlled manual tissue dissection to allow safe and repeatable separation of endothelium and Descemet's membranes from donor corneoscleral buttons for transplantation2.

Video: Corneal Donor Tissue Preparation for Descemet's Membrane Endothelial Keratoplasty

Single Port Donor Nephrectomy

In 2007, Rane presented the first single port nephrectomy for a small non-functioning kidney at the World Congress of Endourology. Since that time, the use of single port surgery for nephrectomy has expanded to include donor nephrectomy. Over the next two years the technique was adopted for many others types of nephrectomies to include donor nephrectomy. We present our technique for single port donor nephrectomy using the Gelpoint device. We have successfully performed this surgery in over 100 patients and add this experience to our experience of over 1000 laparoscopic nephrectomies. With the proper equipment and technique, single port donor nephrectomy can be performed safely and effectively in the majority of live donors. We have found that our operative times and most importantly our transplant outcomes have not changed significantly with the adoption of the single port donor nephrectomy. We believe that single port donor nephrectomy represents a step forward in the care of living donors.

Single port laparoscopic surgery is changing the standard of care in surgical care like nothing since the laparoscopic technique was introduced 20 years ago. We present out technique of single port donor nephrectomy using the Gelpoint device. We have successfully performed this surgery in 100 patients.

In 2007, Rane presented the first single port nephrectomy for a small non-functioning kidney at the World Congress of Endourology.  Since that time, the ...

Corneal Donor Tissue Preparation for Endothelial Keratoplasty

Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes1,2. Since its inception, traditional full thickness corneal transplantation has been the treatment to restore sight in those limited by corneal disease. Some disadvantages to this approach include a high degree of post-operative astigmatism, lack of predictable refractive outcome, and disturbance to the ocular surface. The development of Descemet's stripping endothelial keratoplasty (DSEK), transplanting only the posterior corneal stroma, Descemet's membrane, and endothelium, has dramatically changed treatment of corneal endothelial disease. DSEK is performed through a smaller incision; this technique avoids 'open sky' surgery with its risk of hemorrhage or expulsion, decreases the incidence of postoperative wound dehiscence, reduces unpredictable refractive outcomes, and may decrease the rate of transplant rejection3-6.
Initially, cornea donor posterior lamellar dissection for DSEK was performed manually1 resulting in variable graft thickness and damage to the delicate corneal endothelial tissue during tissue processing. Automated lamellar dissection (Descemet's stripping automated endothelial keratoplasty, DSAEK) was developed to address these issues. Automated dissection utilizes the same technology as LASIK corneal flap creation with a mechanical microkeratome blade that helps to create uniform and thin tissue grafts for DSAEK surgery with minimal corneal endothelial cell loss in tissue processing.
Eye banks have been providing full thickness corneas for surgical transplantation for many years. In 2006, eye banks began to develop methodologies for supplying precut corneal tissue for endothelial keratoplasty. With the input of corneal surgeons, eye banks have developed thorough protocols to safely and effectively prepare posterior lamellar tissue for DSAEK surgery. This can be performed preoperatively at the eye bank. Research shows no significant difference in terms of the quality of the tissue7 or patient outcomes8,9 using eye bank precut tissue versus surgeon-prepared tissue for DSAEK surgery. For most corneal surgeons, the availability of precut DSAEK corneal tissue saves time and money10, and reduces the stress of performing the donor corneal dissection in the operating room. In part because of the ability of the eye banks to provide high quality posterior lamellar corneal in a timely manner, DSAEK has become the standard of care for surgical management of corneal endothelial disease.
The procedure that we are describing is the preparation of the posterior lamellar cornea at the eye bank for transplantation in DSAEK surgery (Figure 1).

Endothelial corneal transplantation is a surgical technique for treatment of posterior corneal diseases. Mechanical microkeratome dissection to prepare tissue results in thinner, more symmetric grafts with less endothelial cell loss and improved outcomes. Dissections can be performed at the eye bank prior to corneal transplantation surgery.

Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes1,2. Since its inception, traditional full ...

Preparation and In Vitro Characterization of Magnetized miR-modified Endothelial Cells

To date, the available surgical and pharmacological treatments for cardiovascular diseases (CVD) are limited and often palliative. At the same time, gene and cell therapies are highly promising alternative approaches for CVD treatment. However, the broad clinical application of gene therapy is greatly limited by the lack of suitable gene delivery systems. The development of appropriate gene delivery vectors can provide a solution to current challenges in cell therapy. In particular, existing drawbacks, such as limited efficiency and low cell retention in the injured organ, could be overcome by appropriate cell engineering (i.e., genetic) prior to transplantation. The presented protocol describes the efficient and safe transient modification of endothelial cells using a polyethyleneimine superparamagnetic magnetic nanoparticle (PEI/MNP)-based delivery vector. Also, the algorithm and methods for cell characterization are defined. The successful intracellular delivery of microRNA (miR) into human umbilical vein endothelial cells (HUVECs) has been achieved without affecting cell viability, functionality, or intercellular communication. Moreover, this approach was proven to cause a strong functional effect in introduced exogenous miR. Importantly, the application of this MNP-based vector ensures cell magnetization, with accompanying possibilities of magnetic targeting and non-invasive MRI tracing. This may provide a basis for magnetically guided, genetically engineered cell therapeutics that can be monitored non-invasively with MRI.

Preparation and In Vitro Characterization of Magnetized miR-modified Endothelial Cells

This manuscript describes the efficient, non-viral delivery of miR to endothelial cells by a PEI/MNP vector and their magnetization. Thus, in addition to genetic modification, this approach allows for magnetic cell guidance and MRI detectability. The technique can be used to improve the characteristics of therapeutic cell products.

To date, the available surgical and pharmacological treatments for cardiovascular diseases (CVD) are limited and often palliative. At the same time, gene ...

Ex Vivo Corneal Organ Culture Model for Wound Healing Studies

The cornea has been used extensively as a model system to study wound healing. The ability to generate and utilize primary mammalian cells in two dimensional (2D) and three dimensional (3D) culture has generated a wealth of information not only about corneal biology but also about wound healing, myofibroblast biology, and scarring in general. The goal of the protocol is an assay system for quantifying myofibroblast development, which characterizes scarring. We demonstrate a corneal organ culture ex vivo model using pig eyes. In this anterior keratectomy wound, corneas still in the globe are wounded with a circular blade called a trephine. A plug of approximately 1/3 of the anterior cornea is removed including the epithelium, the basement membrane, and the anterior part of the stroma. After wounding, corneas are cut from the globe, mounted on a collagen/agar base, and cultured for two weeks in supplemented-serum free medium with stabilized vitamin C to augment cell proliferation and extracellular matrix secretion by resident fibroblasts. Activation of myofibroblasts in the anterior stroma is evident in the healed cornea. This model can be used to assay wound closure, the development of myofibroblasts and fibrotic markers, and for toxicology studies. In addition, the effects of small molecule inhibitors as well as lipid-mediated siRNA transfection for gene knockdown can be tested in this system.

A protocol for an ex vivo corneal organ culture model useful for wound healing studies is described. This model system can be used to assess the effects of agents to promote regenerative healing or drug toxicity in an organized 3D multicellular environment.

The cornea has been used extensively as a model system to study wound healing. The ability to generate and utilize primary mammalian cells in two ...

A Porcine Corneal Endothelial Organ Culture Model Using Split Corneal Buttons

Experimental research on corneal endothelial cells is associated with several difficulties. Human donor corneas are scarce and rarely available for experimental investigations as they are normally needed for transplantation. Endothelial cell cultures often do not translate well to in vivo situations. Due to the biostructural characteristics of non-human corneas, stromal swelling during cultivation induces substantial corneal endothelial cell loss, which makes it difficult to perform cultivation for an extended period of time. Deswelling agents such as dextran are used to counteract this response. However, they also cause significant endothelial cell loss. Therefore, an ex vivo organ culture model not requiring deswelling agents was established. Pig eyes from a local slaughterhouse were used to prepare split corneal buttons. After partial corneal trephination, the outer layers of the cornea (epithelium, bowman layer, parts of the stroma) were removed. This significantly reduces corneal endothelial cell loss induced by massive stromal swelling and Descemet&#39;s membrane folding throughout longer cultivation periods and improves general preservation of the endothelial cell layer. Subsequent complete corneal trephination was followed by the removal of the split corneal button from the remaining eye bulb and cultivation. Endothelial cell density was assessed at follow-up times of up to 15 days after preparation (i.e., days 1, 8, 15) using light microscopy. The preparation technique used allows a better preservation of the endothelial cell layer enabled by less stromal tissue swelling, which results in slow and linear decline rates in split corneal buttons comparable to human donor corneas. As this standardized organo-typically cultivated research model for the first time allows a stable cultivation for at least two weeks, it is a valuable alternative to human donor corneas for future investigations of various external factors with regards to their effects on the corneal endothelium.

Here, a step-by-step protocol for the preparation and cultivation of porcine split corneal buttons is presented. As this organo-typically cultivated organ culture model shows cell death rates within 15 days, comparable to human donor corneas, it represents the first model allowing long-term cultivation of non-human corneas without adding toxic dextran.

Experimental research on corneal endothelial cells is associated with several difficulties. Human donor corneas are scarce and rarely available for ...

Development of a Noninvasive, Laser-Assisted Experimental Model of Corneal Endothelial Cell Loss

Nd:YAG lasers have been used to perform noninvasive intraocular surgery, such as capsulotomy for several decades now. The incisive effect relies on the optical breakdown at the laser focus. Acoustic shock waves and cavitation bubbles are generated, causing tissue rupture. Bubble sizes and pressure amplitudes vary with pulse energy and position of the focal point. In this study, enucleated porcine eyes were positioned in front of a commercially available Nd:YAG laser. Variable pulse energies as well as different positions of the focal spots posterior to the cornea were tested. Resulting lesions were evaluated by two-photon microscopy and histology to determine the best parameters for an exclusive detachment of corneal endothelial cells (CEC) with minimum collateral damage. The advantages of this method are the precise ablation of CEC, reduced collateral damage, and above all, the non-contact treatment.

Here, we present a protocol to detach corneal endothelial cells (CEC) from Descemet&#8217;s membrane (DM) using a neodymium:YAG (Nd:YAG) laser as an ex vivo disease model for bullous keratopathy (BK).

Nd:YAG lasers have been used to perform noninvasive intraocular surgery, such as capsulotomy for several decades now. The incisive effect relies on the ...

An Epithelial Abrasion Model for Studying Corneal Wound Healing

The cornea is critical for vision, accounting for about two-thirds of the refractive power of the eye. Crucial to the role of the cornea in vision is its transparency. However, due to its external position, the cornea is highly susceptible to a wide variety of injuries that can lead to the loss of corneal transparency and eventual blindness. Efficient corneal wound healing in response to these injuries is pivotal for maintaining corneal homeostasis and preservation of corneal transparency and refractive capabilities. In events of compromised corneal wound healing, the cornea becomes vulnerable to infections, ulcerations, and scarring. Given the fundamental importance of corneal wound healing to the preservation of corneal transparency and vision, a better understanding of the normal corneal wound healing process is a prerequisite to understanding impaired corneal wound healing associated with infection and disease. Toward this goal, murine models of corneal wounding have proven useful in furthering our understanding of the corneal wound healing mechanisms operating under normal physiological conditions. Here, a protocol for creating a central corneal epithelial abrasion in mouse using a trephine and a blunt golf club spud is described. In this model, a 2 mm diameter circular trephine, centered over the cornea, is used to demarcate the wound area. The golf club spud is used with care to debride the epithelium and create a circular wound without damaging the corneal epithelial basement membrane. The resulting inflammatory response proceeds as a well-characterized cascade of cellular and molecular events that are critical for efficient wound healing. This simple corneal wound healing model is highly reproducible and well-published and is now being used to evaluate compromised corneal wound healing in the context of disease.

Here, a protocol for creating a central corneal epithelial abrasion wound in the mouse using a trephine and a blunt golf club spud is described. This corneal wound healing model is highly reproducible and is now being used to evaluate compromised corneal wound healing in the context of diseases.

The cornea is critical for vision, accounting for about two-thirds of the refractive power of the eye. Crucial to the role of the cornea in vision is its ...

A Porcine Heterotopic Heart Transplantation Protocol for Delivery of Therapeutics to a Cardiac Allograft

Cardiac transplantation is the gold standard treatment for end-stage heart failure. However, it remains limited by the number of available donor hearts and complications such as primary graft dysfunction and graft rejection. The recent clinical use of an ex vivo perfusion device in cardiac transplantation introduces a unique opportunity for treating cardiac allografts with therapeutic interventions to improve function and avoid deleterious recipient responses. Establishing a translational, large-animal model for therapeutic delivery to the entire allograft is essential for testing novel therapeutic approaches in cardiac transplantation. The porcine, heterotopic heart transplantation model in the intraabdominal position serves as an excellent model for assessing the effects of novel interventions and the immunopathology of graft rejection. This model additionally offers long-term survival for the pig, given that the graft is not required to maintain the recipient's circulation. The aim of this protocol is to provide a reproducible and robust approach for achieving ex vivo delivery of a therapeutic to the entire cardiac allograft prior to transplantation and provide technical details to perform a survival heterotopic transplant of the ex vivo perfused heart.

We present a protocol for utilizing a normothermic ex vivo sanguinous perfusion system for the delivery of therapeutics to an entire cardiac allograft in a porcine heterotopic heart transplant model.

Cardiac transplantation is the gold standard treatment for end-stage heart failure. However, it remains limited by the number of available donor hearts ...

A Human Corneal Organ Culture Model of Descemet's Stripping Only with Accelerated Healing Stimulated by Engineered Fibroblast Growth Factor 1

Fuchs Endothelial Corneal Dystrophy (FECD) results from dysfunctional corneal endothelial cells (CECs) and is currently treated by transplantation of the whole cornea or Descemet's membrane. Recent developments in ocular surgery have established Descemet's Stripping Only (DSO), a surgical technique in which a central circle of guttae-dense Descemet's membrane is removed to allow for the migration of CECs onto the smooth stroma, restoring function and vision to the cornea. While this potential treatment option is of high interest in the field of ophthalmic research, no successful ex vivo models of DSO have been established and clinical data is limited. This work presents a novel wound-healing model simulating DSO in human donor corneas. Using this approach to evaluate the efficacy of the human engineered FGF1 (NM141), we found that treatment accelerated healing via stimulation of migration and proliferation of CECs. This finding was confirmed in 11 pairs of human corneas with signs of dystrophy reported by the eye banks in order to verify that these results can be replicated in patients with Fuchs' Dystrophy, as the target population of the DSO procedure.

A Human Corneal Organ Culture Model of Descemet&#039;s Stripping Only with Accelerated Healing Stimulated by Engineered Fibroblast Growth Factor 1

Descemet's Stripping Only is an experimental procedure wherein patients with central corneal guttae resulting from Fuchs Endothelial Corneal Dystrophy have Descemet's membrane stripped for peripheral cells to regenerate the endothelial layer. We present novel methodology simulating DSO in dystrophic human corneas ex vivo with accelerated healing stimulated by eFGF1 (NM141).

Fuchs Endothelial Corneal Dystrophy (FECD) results from dysfunctional corneal endothelial cells (CECs) and is currently treated by transplantation of the ...

Preparation of Human Myocardial Tissue for Long-Term Cultivation

Cardiomyocyte cultivation has seen a vast number of developments, ranging from two-dimensional (2D) cell cultivation to iPSC derived organoids. In 2019, an ex vivo way to cultivate myocardial slices obtained from human heart samples was demonstrated, while approaching in vivo condition of myocardial contraction. These samples originate mostly from heart transplantations or left-ventricular assist device placements. Using a vibratome and a specially developed cultivation system, 300 &#181;m thick slices are placed between a fixed and a spring wire, allowing for stable and reproducible cultivation for several weeks. During cultivation, the slices are continuously stimulated according to individual settings. Contractions can be displayed and recorded in real-time, and pharmacological agents can be readily applied. User-defined stimulation protocols can be scheduled and performed to assess vital contraction parameters like post-pause-potentiation, stimulation threshold, force-frequency relation, and refractory period. Furthermore, the system enables a variable pre- and afterload setting for a more physiological cultivation.
Here, we present a step-by-step guide on how to generate a successful long-term cultivation of human left ventricular myocardial slices, using a commercial biomimetic cultivation solution.

We present a protocol for ex vivo cultivation of human ventricular myocardial tissue. It allows for detailed analysis of contraction force and kinetics, as well as the application of pre- and afterload to mimic the in vivo physiological environment more closely.

Cardiomyocyte cultivation has seen a vast number of developments, ranging from two-dimensional (2D) cell cultivation to iPSC derived organoids. In 2019, ...