DMEK

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Green
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Joined: Wed 18 Apr 2018 1:29 pm
Keratoconus: Yes, I have KC
Vision: Contact lenses

DMEK

Postby Green » Fri 29 May 2020 10:24 pm

Anyone had a DMEK for 1st PK or re-graft PK rejection?

PhilLer
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Keratoconus: Yes, I have KC
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Re: DMEK

Postby PhilLer » Fri 05 Feb 2021 7:53 pm

No in my knowledge, but using DMEK may be a good option for people after failure of 1st penetrating keratoplasty.

PhilLer
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Posts: 23
Joined: Sun 14 Oct 2018 1:20 pm
Keratoconus: Yes, I have KC
Vision: Graft(s) and spectacles

Re: DMEK

Postby PhilLer » Fri 12 Feb 2021 12:13 am

After DMEK (only grafting endothelium), the time to recover is faster than for PK. The lifespan of the graft after DMEK may be comparable to the lifespan of the graft after PK (possibly sightly lower, more studies about DMEK are necessary).

PhilLer
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Posts: 23
Joined: Sun 14 Oct 2018 1:20 pm
Keratoconus: Yes, I have KC
Vision: Graft(s) and spectacles

Re: DMEK

Postby PhilLer » Fri 12 Feb 2021 10:52 am

More info here about potential corneal endothelial cell regeneration (in the transition zone at the periphery of the cornea):

Cells. 2019 Oct 12;8(10):1244. doi: 10.3390/cells8101244.
Characterization of Human Transition Zone Reveals a Putative Progenitor-Enriched Niche of Corneal Endothelium
Gary Hin-Fai Yam 1 2, Xinyi Seah 3, Nur Zahirah Binte M Yusoff 4, Melina Setiawan 5, Stephen Wahlig 6 7, Hla Myint Htoon 8 9, Gary S L Peh 10 11, Viridiana Kocaba 12 13, Jodhbir S Mehta 14 15 16 17
Affiliations expand
PMID: 31614883 PMCID: PMC6829622 DOI: 10.3390/cells8101244
Free PMC article
Abstract
: The corneal endothelium regulates corneal hydration to maintain the transparency of cornea. Lacking regenerative capacity, corneal endothelial cell loss due to aging and diseases can lead to corneal edema and vision loss. There is limited information on the existence of corneal endothelial progenitors. We conducted ultrastructural examinations and expression analyses on the human transition zone (TZ) at the posterior limbus of corneal periphery, to elucidate if the TZ harbored progenitor-like cells, and to reveal their niche characteristics. Within the narrow TZ (~190 μm width), the inner TZ-adjacent to the peripheral endothelium (PE)-contained cells expressing stem/progenitor markers (Sox2, Lgr5, CD34, Pitx2, telomerase). They were located on the inner TZ surface and in its underlying stroma. Lgr5 positive cells projected as multicellular clusters into the PE. Under transmission electron microscopy and serial block face-scanning electron microscopy and three-dimensional (3D) reconstruction, the terminal margin of Descemet's membrane was inserted beneath the TZ surface, with the distance akin to the inner TZ breadth. Porcine TZ cells were isolated and proliferated into a confluent monolayer and differentiated to cells expressing corneal endothelial markers (ZO1, Na+K+ATPase) on cell surface. In conclusion, we have identified a novel inner TZ containing progenitor-like cells, which could serve the regenerative potential for corneal endothelium.

Keywords: cell culture; corneal endothelial progenitors; corneal endothelium; morphology; posterior limbus; transition zone.
https://pubmed.ncbi.nlm.nih.gov/31614883/


About DMEK and other endothial cell transplantation techniques:

Ther Adv Ophthalmol. 2018 Jan-Dec; 10: 2515841418815802.
Published online 2018 Dec 7. doi: 10.1177/2515841418815802
PMCID: PMC6293368
PMID: 30560230
Corneal endothelial cell dysfunction: etiologies and management
Sepehr Feizi
Author information Article notes Copyright and License information Disclaimer
This article has been cited by other articles in PMC.
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Abstract
A transparent cornea is essential for the formation of a clear image on the retina. The human cornea is arranged into well-organized layers, and each layer plays a significant role in maintaining the transparency and viability of the tissue. The endothelium has both barrier and pump functions, which are important for the maintenance of corneal clarity. Many etiologies, including Fuchs’ endothelial corneal dystrophy, surgical trauma, and congenital hereditary endothelial dystrophy, lead to endothelial cell dysfunction. The main treatment for corneal decompensation is replacement of the abnormal corneal layers with normal donor tissue. Nowadays, the trend is to perform selective endothelial keratoplasty, including Descemet stripping automated endothelial keratoplasty and Descemet’s membrane endothelial keratoplasty, to manage corneal endothelial dysfunction. This selective approach has several advantages over penetrating keratoplasty, including rapid recovery of visual acuity, less likelihood of graft rejection, and better patient satisfaction. However, the global limitation in the supply of donor corneas is becoming an increasing challenge, necessitating alternatives to reduce this demand. Consequently, in vitro expansion of human corneal endothelial cells is evolving as a sustainable choice. This method is intended to prepare corneal endothelial cells in vitro that can be transferred to the eye. Herein, we describe the etiologies and manifestations of human corneal endothelial cell dysfunction. We also summarize the available options for as well as recent developments in the management of corneal endothelial dysfunction.

Keywords: corneal endothelial dysfunction, etiologies, human corneal endothelium, management
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6293368/


About actually/the close future on endothelium understanding and management:

Journal of Cellular Physiology
REVIEW ARTICLE
Full Access
Corneal endothelium tissue engineering: An evolution of signaling molecules, cells, and scaffolds toward 3D bioprinting and cell sheets
Mostafa Khalili Maryam Asadi Houman Kahroba Mohammad Reza Soleyman Helder Andre Effat Alizadeh
First published: 08 October 2020
SECTIONSPDFPDFTOOLS SHARE
Abstract
Cornea is an avascular and transparent tissue that focuses light on retina. Cornea is supported by the corneal‐endothelial layer through regulation of hydration homeostasis. Restoring vision in patients afflicted with corneal endothelium dysfunction‐mediated blindness most often requires corneal transplantation (CT), which faces considerable constrictions due to donor limitations. An emerging alternative to CT is corneal endothelium tissue engineering (CETE), which involves utilizing scaffold‐based methods and scaffold‐free strategies. The innovative scaffold‐free method is cell sheet engineering, which typically generates cell layers surrounded by an intact extracellular matrix, exhibiting tunable release from the stimuli‐responsive surface. In some studies, scaffold‐based or scaffold‐free technologies have been reported to achieve promising outcomes. However, yet some issues exist in translating CETE from bench to clinical practice. In this review, we compare different corneal endothelium regeneration methods and elaborate on the application of multiple cell types (stem cells, corneal endothelial cells, and endothelial precursors), signaling molecules (growth factors, cytokines, chemical compounds, and small RNAs), and natural and synthetic scaffolds for CETE. Furthermore, we discuss the importance of three‐dimensional bioprinting strategies and simulation of Descemet's membrane by biomimetic topography. Finally, we dissected the recent advances, applications, and prospects of cell sheet engineering for CETE.

https://onlinelibrary.wiley.com/doi/ful ... /jcp.30085

Philippe


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