Preincubation of donor tissue with a VEGF cytokine trap promotes subsequent high-risk corneal transplant survival

AimsPathological neovascularisation of the host bed and the transplant itself is the main risk factor for graft rejection after corneal transplantation. This study aims to prevent this process by preincubation of the corneal donor tissue ex vivo with an antivascular endothelial growth factor (VEGF) cytokine trap blocking additional postsurgical hemangiogenesis and lymphangiogenesis to promote high-risk graft survival.MethodsThe donor tissue was preincubated with a VEGFR1R2 cytokine trap for 24 hours prior to murine high-risk corneal transplantation (human IgG Fc was used as the control). The distribution of VEGFR1R2 Trap in the cornea was investigated by immunohistochemistry. Corneas were excised to quantify the blood vessels (BVs) and lymphatic vessels (LVs) and draining lymph nodes (dLNs) were harvested to analyse the phenotype of dendritic cells (DCs) and T cells at week 1, 2 and 8 post-transplantation. Graft survival was compared between preincubation with VEGFR1R2 Trap and human IgG Fc in high-risk recipients.ResultsVEGFR1R2 Trap was present in the graft for at least 2 weeks after surgery and additionally diffused into the corneal recipient. BVs, LVs and macrophages in the whole cornea were significantly decreased 1-week and 2-week post-transplantation (p<0.05). In dLNs the frequency of CD11c+DCs was significantly reduced, whereas CD200R+ regulatory DCs were significantly increased after keratoplasty (p<0.05). Furthermore, long-term high-risk graft survival was significantly improved (p<0.01).ConclusionsPreincubation of corneal donor tissue with a VEGFR1R2 cytokine trap can significantly promote subsequent high-risk corneal transplant survival and thereby opens new treatment avenues for high-risk corneal transplantation.

Supramolecular Host–Guest Hydrogels for Corneal Regeneration

Over 6.2 million people worldwide suffer from moderate to severe vision loss due to corneal disease. While transplantation with allogenic donor tissue is sight-restoring for many patients with corneal blindness, this treatment modality is limited by long waiting lists and high rejection rates, particularly in patients with severe tissue damage and ocular surface pathologies. Hydrogel biomaterials represent a promising alternative to donor tissue for scalable, nonimmunogenic corneal reconstruction. However, implanted hydrogel materials require invasive surgeries and do not precisely conform to tissue defects, increasing the risk of patient discomfort, infection, and visual distortions. Moreover, most hydrogel crosslinking chemistries for the in situ formation of hydrogels exhibit off-target effects such as cross-reactivity with biological structures and/or result in extractable solutes that can have an impact on wound-healing and inflammation. To address the need for cytocompatible, minimally invasive, injectable tissue substitutes, host–guest interactions have emerged as an important crosslinking strategy. This review provides an overview of host–guest hydrogels as injectable therapeutics and highlights the potential application of host–guest interactions in the design of corneal stromal tissue substitutes.

The Use of Tutoplast as an Adjunct in Scleral Buckle Procedure in Patients with Extremely Thin Sclera

Extremely thin sclera often necessitates abortion of scleral buckle procedures. In patients in whom a scleral buckle is desired, previous techniques have included the use of cyanoacrylate glue and continuing with surgery or placing donor tissue over the areas of thin sclera, but this can delay surgery. This was a retrospective review of three patients with thin sclera encountered during scleral buckling procedures. All patients had Tutoplast Pericardial Graft placed over the areas of thin sclera which allowed the scleral buckle to be sutured onto the Tutoplast rather than the thin sclera. Tutoplast Pericardial Graft is a useful adjunct in scleral buckle procedures with extremely thin sclera, and a scleral buckle can be safely placed over it and lead to successful retinal reattachment.

Viability, yield and expansion capability of feline MSCs obtained from subcutaneous and reproductive organ adipose depots

Background The source of multipotent stromal cells (MSC) can have a significant influence on the health and expansion capacity of the cells. As the applications for allogeneic MSCs in the treatment of feline diseases increase, the location of the initial donor tissue must be analyzed. To date, comparisons have only been made between feline MSCs collected from bone marrow or abdominal fat. This is the first report to compare cells obtained from different adipose depots in the cat with a focus on clinically relevant donor tissues. The tissue was collected from 34 healthy cats undergoing spaying (fat around the ovaries and uterine horn) or subcutaneous fat collected during surgical procedures. Results The amount of starting material is essential to isolate sufficient MSCs. The total tissue yield from the subcutaneous fat was significantly greater than could be obtained from around the reproductive organs, leading to 3 times more MSCs per donor. However, the concentration of MSCs obtained from reproductive fat was higher than from subcutaneous fat. In addition, the viability of the MSCs from the reproductive fat was significantly higher than the subcutaneous fat. Since most spaying occurs in young cats (under 18 months) reproductive fat was collected from adult cats during spaying, illustrating that age did not alter the yield or viability of the MSCs. When sufficient tissue was collected, it was digested either mechanically or enzymatically. Mechanical digestion further decreased the viability and yield of MSCs from subcutaneous fat compared to enzymatic digestion. Biomarkers of stem cell characterization, expansion capacity and function were detected using qPCR. CD70, CD90 and CD105 were all expressed in high levels in the 3 groups. However, the reproductive fat had higher levels of CD73 with the mechanically digested subcutaneous fat having the least. Gata6 was detected in all samples while Sox2 and Sox17 were also detected with higher quantities found in the enzymatically digested subcutaneous fat. Negative control genes of Gata4 and Pdx1 showed no detection prior to 50 cycles. During the first three passages, age of the donor, location of the donor tissue, or digestion protocol had no effect on cell culture doubling times or cell viability. Conclusions While MSCs from reproductive fat had superior cells/tissue weight and initial viability, there were still dramatically fewer cells obtained compared to subcutaneous fat due to the limited amount of tissue surrounding the reproductive organs. Further, in P1-P3 cultures there were no differences noted in doubling time or cell viability between tissue obtained from reproductive or subcutaneous fat depots.

The Origin of the Cyathea delgadii Sternb. Somatic Embryos Is Determined by the Developmental State of Donor Tissue and Mutual Balance of Selected Metabolites

Somatic embryogenesis is the formation of a plant embryo from a cell other than the product of gametic fusion. The need to recognize the determinants of somatic cell fate has prompted investigations on how endogenous factors of donor tissues can determine the pattern of somatic embryo origin. The undertaking of this study was enabled by the newly developed experimental system of somatic embryogenesis of the tree fern Cyathea delgadii Sternb., in which the embryos are produced in hormone-free medium. The contents of 89 endogenous compounds (such as sugars, auxins, cytokinins, gibberellins, stress-related hormones, phenolic acids, polyamines, and amino acids) and cytomorphological features were compared between two types of explants giving rise to somatic embryos of unicellular or multicellular origin. We found that a large content of maltose, 1-kestose, abscisic acid, biologically active gibberellins, and phenolic acids was characteristic for single-cell somatic embryo formation pattern. In contrast, high levels of starch, callose, kinetin riboside, arginine, and ethylene promoted their multicellular origin. Networks for visualization of the relations between studied compounds were constructed based on the data obtained from analyses of a Pearson correlation coefficient heatmap. Our findings present for the first time detailed features of donor tissue that can play an important role in the somatic-to-embryogenic transition and the somatic embryo origin.