Most corneal diseases affect corneal stroma and include immune or infectious diseases, ecstatic disorders, traumatic scars, and corneal dystrophies. Cell-based therapy is a promising therapeutic approach to overcome the current disadvantages of corneal transplantation. We intended to search for a cell source to repopulate and regenerate corneal stroma. We investigated the ability of human processed lipoaspirate derived (PLA) cells to regenerate corneal stroma in experimental animals. In the first set of experiments, we tested the biosafety and immunogenicity of human PLA stem cells transplanted into the corneal stroma of rabbits. No immune response was elicited even though we used immune-competent animals. PLA cells survived up to 10 weeks post-transplant, maintained their shape, and remained intermingled in the stroma without disrupting its histological pattern. Interestingly, transparency was preserved even 10 weeks after the transplant, when PLA cells formed a discontinuous layer in the stroma. In the second set of experiments, regeneration of the corneal stroma by PLA cells was assessed, creating a niche by partial ablation of the stroma. After 12 weeks, human cells were disposed following a multilayered pattern and differentiated into functional keratocytes, as assessed by the expression of aldehyde-3-dehydrogenase and cornea-specific proteoglycan keratocan. Based on our results, we believe that adipose-derived adult stem cells can be a cell source for stromal regeneration and repopulation in diseased corneas. The low health impact of the surgical procedure performed to obtain the PLA cells provides this cell source with an additional beneficial feature for its possible future autologous use in human patients.

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Background: Autologous platelet-rich plasma (PRP) has been proven to be very effective on tissue regeneration and wound healing. Here we investigate the potential use of PRP in the treatment of symptomatic dry eye. Methods: Eighteen consecutive patients with symptomatic dry eye were treated with topical PRP and followed up for 1 month. Disappearance of subjective symptoms, increase in best corrected visual acuity, tear meniscus, tear breakup time, decrease in inflammation, fluorescein staining and improvement in impression cytology were measured. Results: Symptoms improved significantly in 89% of the patients, 28% improved at least 1 line of best corrected visual acuity. A significant improvement on lachrymal meniscus and conjunctival hyperemia and a decrease or disappearance of corneal fluorescein staining were observed. Impression cytology revealed a significant increase in conjunctival goblet cells. Conclusion: Treatment of patients suffering from significant dry eye symptoms with autologous RPR proved to be very effective, improving both patient symptoms and major clinical signs.

One of the main issues in the development of new biocolonizable materials is to understand the influence of the synthetic material on the biological response in terms of cellular adhesion, proliferation, and differentiation. In this study, we characterized different polymeric materials (with different hydrophobicity/hydrophilicity ratios and electrical charges) using dynamic-mechanical analysis, equilibrium water content, and surface energy. Cell adhesion, viability, morphology, and proliferation studies were conducted with these materials using a conjunctival epithelial cell line (IOBA-NHC). The biological data regarding physicochemical parameters of the materials were also correlated. When conjunctival epithelial cells were grown on poly(ethyl acrylate-co-hydroxyethyl acrylate) copolymers, P(EA-co-HEA), samples with up to 20% hydrophilic groups on their polymeric chain showed adhesion, viability, and proliferation, although these three factors decreased as the hydrophilic group content increased. The poly(ethyl acrylate-co-methacrylic acid) 90/10 copolymer, P(EA-co-MAAc) 90/10, showed better results than poly(ethyl acrylate-co-hydroxyethyl acrylate) copolymers and were even better than tissue control polystyrene (TCPS). This feature is explained by the presence of electrical charges on the surface of the poly(ethyl acrylate-co-methacrylic acid) 90/10 copolymer. The fact that the ionic groups are configured in domains structured in nanophases as happens in this copolymer improves cell adhesion even further.

PURPOSE: To ascertain the usefulness of platelet-rich plasma in the treatment of patients suffering from symptomatic ocular surface syndrome following LASIK. METHODS: Twenty-six eyes (9 women and 4 men) affected by symptomatic ocular surface syndrome were treated with topical eye drops of autologous platelet-rich plasma and results were reported at 4 weeks. Topical platelet-rich plasma was prepared from total blood and enriched in platelets by centrifugation. RESULTS: Eighty-five percent of patients experienced significant improvement of symptoms; best spectacle-corrected visual acuity increased 1 to 2 lines in 54%; fluorescein staining analysis showed a 69% full fluorescein disappearance; and tear break-up time increased >2 seconds in 46%. Only one patient developed intolerance to platelet-rich plasma after 4 weeks. CONCLUSIONS: Autologous platelet-rich plasma was effective in the treatment of patients with ocular surface syndrome following LASIK, with symptoms generally relieved and a positive effect on punctate keratitis. [J Refract Surg. 2007;23:617-619.]

There is a paucity of knowledge concerning the immunologic sequelae that culminate in overt autoimmunity. In the present study, we have analyzed the factors that lead to disease in the model of autoimmunity, murine experimental autoimmune encephalomyelitis (EAE). EAE in H-2u mice involves autoreactive CD4+ T cells that are induced by immunization with the immunodominant N-terminal epitope of myelin basic protein. The affinity of this epitope for I-Au can be increased by substituting lysine at position 4 with tyrosine, and this can be used to increase the effective Ag dose. Paradoxically, high doses of Ag are poorly encephalitogenic. We have used quantitative analyses to study autoreactive CD4+ T cell responses following immunization of mice with Ag doses that are at the extremes of encephalitogenicity. A dose of autoantigen that is poorly encephalitogenic results in T cell hyperresponsiveness, triggering an anti-inflammatory feedback loop in which IFN-γ plays a pivotal role. Our studies define a regulatory mechanism that serves to limit overly robust T cell responses. This feedback regulation has broad relevance to understanding the factors that determine T cell responsiveness.

The novel coronavirus SARS-CoV-2, which causes the disease commonly known as COVID-19, has spread around the world, associated mostly with respiratory tract symptoms. We report the first case of a thyrotoxic crisis precipitated by COVID-19 and describe its identification, diagnosis, and management in the emergency unit. We also conduct a systematic review of thyrotoxic crisis literature and COVID-19 infection. This case highlights the importance of considering the SARS-CoV2 virus as a potential trigger of a thyroid storm. It also shows the need to maintain extreme contact precautions even after one month of COVID-19 symptom onset.

We have used T cells bearing TCRs that are closely related in sequence as probes to detect conformational variants of peptide-MHC complexes in murine experimental autoimmune encephalomyelitis in H-2u mice. The N-terminal epitope of myelin basic protein (MBP) is immunodominant in this model. Our studies have primarily focused on T cell recognition of a position 4 analog of this peptide (MBP1–9[4Y]) complexed with I-Au. Using site-directed mutagenesis, we have mapped the functionally important complementarity determining region residues of the 1934.4 TCR Vα domain. One of the resulting mutants (Tyr95 to alanine in CDR3α, Y95A) has interesting properties: relative to the parent wild-type TCR, this mutant poorly recognizes Ag complexes generated by pulsing professional APCs (PL-8 cells) with MBP1–9[4Y] while retaining recognition of MBP1–9[4Y]-pulsed unconventional APCs or insect cell-expressed complexes of I-Au containing tethered MBP1–9[4Y]. Insect cell expression of recombinant I-Au with covalently tethered class II-associated invariant chain peptide or other peptides which bind relatively weakly, followed by proteolytic cleavage of the peptide linker and replacement by MBP1–9[4Y] in vitro, results in complexes that resemble peptide-pulsed PL-8 cells. Therefore, the distinct conformers can be produced in recombinant form. T cells that can distinguish these two conformers can also be generated by the immunization of H-2u mice, indicating that differential recognition of the conformers is observed for responding T cells in vivo. These studies have relevance to understanding the molecular details of T cell recognition in murine experimental autoimmune encephalomyelitis. They are also of particular importance for the effective use of multimeric peptide-MHC complexes to characterize the properties of Ag-specific T cells.