Long-term outcome of cultivated oral mucosal epithelial transplantation for fornix reconstruction in chronic cicatrising diseases

Therapeutic application of decellularized porcine small intestinal submucosa scaffold in conjunctiva reconstruction

The objective of this study was to investigate the biological feasibility and surgical applicability of decellularized porcine small intestinal submucosa (DSIS) in conjunctiva reconstruction. A total of 52 Balb/c mice were included in the study. We obtained the DSIS by decellularization, evaluated the physical and biological properties of DSIS in vitro, and further evaluated the effect of surgical transplantation of DSIS scaffold in vivo. The histopathology and ultrastructural analysis results showed that the scaffold retained the integrity of the fibrous morphology while removing cells. Biomechanical analysis showed that the elongation at break of the DSIS (239.00 ± 12.51%) were better than that of natural mouse conjunctiva (170.70 ± 9.41%, P < 0.05). Moreover, in vivo experiments confirmed the excellent biocompatibility of the decellularized scaffolds. In the DSIS group, partial epithelialization occurred at day-3 after operation, and the conjunctival injury healed at day-7, which was significantly faster than that in human amniotic membrane (AM) and sham surgery (SHAM) group (P < 0.05). The number and distribution of goblet cells of transplanted DSIS were significantly better than those of the AM and SHAM groups. Consequently, the DSIS scaffold shows excellent biological characteristics and surgical applicability in the mouse conjunctival defect model, and DSIS is expected to be an alternative scaffold for conjunctival reconstruction.

Alteration of Gene Expression in Pathological Keratinization of the Ocular Surface

Purpose

To investigate the molecular mechanism of pathological keratinization in the chronic phase of ocular surface (OS) diseases.

Methods

In this study, a comprehensive gene expression analysis was performed using oligonucleotide microarrays on OS epithelial cells obtained from three patients with pathological keratinization (Stevens-Johnson syndrome [n = 1 patient], ocular cicatricial pemphigoid [n = 1 patient], and anterior staphyloma [n = 1 patient]). The controls were three patients with conjunctivochalasis. The expression in some transcripts was confirmed using quantitative real-time PCR.

Results

Compared to the controls, 3118 genes were significantly upregulated by a factor of 2 or more than one-half in the pathological keratinized epithelial cells (analysis of variance P < 0.05). Genes involved in keratinization, lipid metabolism, and oxidoreductase were upregulated, while genes involved in cellular response, as well as known transcription factors (TFs), were downregulated. Those genes were further analyzed with respect to TFs and retinoic acid (RA) through gene ontology analysis and known reports. The expression of TFs MYBL2, FOXM1, and SREBF2, was upregulated, and the TF ELF3 was significantly downregulated. The expression of AKR1B15, RDH12, and CRABP2 (i.e., genes related to RA, which is known to suppress keratinization) was increased more than twentyfold, whereas the expression of genes RARB and RARRES3 was decreased by 1/50. CRABP2, RARB, and RARRES3 expression changes were also confirmed by qRT-PCR.

Conclusions

In pathological keratinized ocular surfaces, common transcript changes, including abnormalities in vitamin A metabolism, are involved in the mechanism of pathological keratinization.

Long-term outcomes of fornix reconstruction and cicatricial entropion repair in ocular mucous membrane pemphigoid and drug-related secondary pemphigoid

OBJECTIVE

To investigate the long-term outcomes of fornix reconstruction and cicatricial entropion repair in patients with ocular mucous membrane pemphigoid (MMP) and secondary MMP.

METHODS

Retrospective chart review of patients with MMP undergoing either fornix reconstruction (with amniotic membrane or buccal mucosal graft) or Wies cicatricial entropion repair between January 1, 2000, and September 1, 2020. Patients had a positive mucosal biopsy and (or) clinical features of MMP or secondary MMP. The primary outcome was overall success of fornix reconstruction based on fornix depth maintenance at latest follow-up. Secondary outcomes included resolution of trichiasis, visual acuity, and improvement of subjective symptoms.

RESULTS

Eight patients (10 eyes) with a diagnosis of MMP (3 males and 5 females; median age, 71 years) and 4 patients (4 eyes) with a diagnosis of secondary MMP (2 females and 2 male; median age, 87 years) were enrolled. Mean follow-up was 22.7 months (range, 0.3-87.5 months) for MMP patients and 15.4 months (range, 3.0-43.9 months) for secondary MMP patients. For MMP eyes, 30.0% underwent fornix reconstruction, 60.0% underwent entropion repair, and 10.0% received both. Re-formation of symblepharon and loss of fornix depth occurred in all MMP eyes at an average of 6.4 ± 7.0 months postoperatively, and trichiasis recurred in all patients at the last follow-up visit. In secondary MMP patients, 75.0% of the eyes showed recurrence of symblepharon, and 66.7% re-formed trichiasis. Both MMP and secondary MMP patients had short-term symptom improvements.

CONCLUSIONS

Fornix reconstruction and cicatricial entropion repair in our cohort of MMP and secondary MMP patients resulted in short-term symptomatic improvement, but recurrence was seen, on average, at 6 months postoperatively.

Recent trends and perspectives in reconstruction and regeneration of intra/extra-oral wounds using tissue-engineered oral mucosa equivalents

Many conditions, including cancer, trauma, and congenital anomalies, can damage the oral mucosa. Multiple cultures of oral mucosal cells have been used for biocompatibility tests and oral biology studies. In recent decades, the clinical translation of tissue-engineered products has progressed significantly in developing tangible therapies and inspiring advancements in medical science. However, the reconstruction of an intraoral mucosa defect remains a significant challenge. Despite the drawbacks of donor-site morbidity and limited tissue supply, the use of autologous oral mucosa remains the gold standard for oral mucosa reconstruction and repair. Tissue engineering offers a promising solution for repairing and reconstructing oral mucosa tissues. Cell- and scaffold-based tissue engineering approaches have been employed to treat various soft tissue defects, suggesting the potential clinical use of tissue-engineered oral mucosa (TEOMs). In this review, we first cover the recent trends in the reconstruction and regeneration of extra-/intra-oral wounds using TEOMs. Next, we describe the current status and challenges of TEOMs. Finally, future strategic approaches and potential technologies to support the advancement of TEOMs for clinical use are discussed.

Strategic combination of cultivated oral mucosal epithelial transplantation and postoperative limbal-rigid contact lens-wear for end-stage ocular surface disease: a retrospective cohort study

PURPOSE

To provide the long-term outcome of patients with end-stage severe ocular surface disease (OSD) consecutively treated with cultivated oral mucosal epithelial transplantation (COMET) followed by limbal-rigid contact lens (CL)-wear therapy.

DESIGN

Retrospective cohort.

METHODS

In 23 eyes of 18 patients with severe OSD who underwent COMET surgery between 2002 and 2019 and who were followed with limbal-rigid CL-wear therapy for at least 1 year postoperative, patient demographics, best-corrected visual acuity (BCVA, logMAR), Ocular Surface Grading Scores (OSGS), surgical indication and adverse events were reviewed. Primary and secondary outcomes were BCVA and OSGS changes at baseline and final examination, respectively.

RESULTS

This study involved 16 patients with Stevens-Johnson syndrome and 2 patients with mucous membrane pemphigoid (mean age: 59±15 years). The indications for COMET were as follows: corneal reconstruction for vision improvement (10 eyes (43.5%)), corneal reconstruction for persistent epithelial defect (4 eyes (17.4%)) and conjunctival (fornix) reconstruction for symblepharon release (9 eyes (39.1%)). The mean duration of CL-wear postsurgery was 6.4±3.9 years (range: 1.4 to 13.3 years). The mean BCVA at baseline and at final follow-up was logMAR 1.9±0.5 and 1.3±0.7, respectively (p<0.05). Compared with those at baseline, the OSGSs for symblepharon and upper and lower fornix shortening showed significant improvement at each follow-up time point post treatment initiation. No serious intraoperative or postoperative adverse events were observed.

CONCLUSION

In patients afflicted with severe OSD, COMET combined with limbal-rigid CL-wear therapy postsurgery was found effective for vision improvement and ocular surface stabilisation.

Insights into the clinical development of regenerative medical products through a comparison of three cell-based products recently approved for limbal stem cell deficiency

Three regenerative medical products for limbal stem cell deficiency (LSCD), a rare and intractable ocular surface disease, have recently been approved in Japan. To our knowledge, this is the first time multiple stem-cell-based medical products have been approved for the same ocular disease. Development plans and study designs for each product differ, resulting in differences in indications. Since cell-based products have a heterogeneous formulation and often target rare diseases, they require a flexible approach to development. This review article describes the status and prospects of the clinical development of regenerative medical products by summarizing the issues of the three products from the Pharmaceuticals and Medical Devices Agency (PMDA) standpoint. Implementing stem cell-based products is challenging, requiring scientific and flexible review by regulatory authorities. To overcome these issues in the development process, developers and regulatory authorities need to communicate and fully discuss study protocols from the early stage of development.

Challenges and concepts in the diagnosis and management of ocular graft-versus-host disease

Graft-versus-host disease (GVHD) is characterized by tissue inflammation in the host following an allogeneic hematopoietic cell transplantation (HCT). The pathophysiology is complex and only incompletely understood yet. Donor lymphocyte interaction with the histocompatibility antigens of the host plays a crucial role in the pathogenesis of the disease. Inflammation may affect multiple organs and tissues, e.g., the gastrointestinal tract, liver, lung, fasciae, vaginal mucosa, and the eye. Subsequently, alloreactive donor-derived T and B lymphocytes may lead to severe inflammation of the ocular surface (i.e., cornea and conjunctiva) and the eyelids. Furthermore, fibrosis of the lacrimal gland may lead to severe dry eye. This review focuses on ocular GVHD (oGVHD) and provides an overview of current challenges and concepts in the diagnosis and management of oGVHD. Ophthalmic manifestations, diagnostic procedures, grading of severity and recommendations for ophthalmic examination intervals are provided. Management of ocular surface disease with lubricants, autologous serum eye drops, topical anti-inflammatory agents and systemic treatment options are described based on the current evidence. Ocular surface scarring and corneal perforation are severe complications of oGVHD. Therefore, ophthalmic screening and interdisciplinary treatment approaches are highly relevant to improve the quality of life of patients and to prevent potentially irreversible visual loss.

Current Advancements in Corneal Cell-Based Therapy

Corneal epithelial stem cells (CEpSCs) mostly reside at the limbal area and are responsible for tissue homeostasis throughout life. Once complete CEpSC deficiency occurs, regenerative medicine cell-based therapy using CEpSCs or their alternatives can provide successful clinical outcomes. Due to an improved understanding of CEpSCs and mucosal epithelial stem cells, major advancements have been made over the past few decades in in vivo and ex vivo cell-based ocular surface reconstruction therapies for the treatment of severe ocular surface diseases. New therapeutic concepts and clinical strategies are emerging for the treatment of corneal endothelial dysfunction. For example, unlike corneal epithelial cells, in vivo corneal endothelial cells (CECs) stop proliferating and are arrested in the G1 phase of the cell cycle due to cell-to-cell contact inhibition and exposure to a high concentration of transforming growth factor-beta in the aqueous humor. Thus, the production of CECs with good functionality in culture has consistently been difficult. To solve this problem, Rho-associated protein kinase inhibition has taken center stage, as it not only makes the production of human CECs in culture closely mimic the functional characteristics of in vivo healthy CECs possible but also helps sustain those biological properties. Thus, cultured human CEC injection therapy is now moving to the forefront for the treatment of corneal endothelial failure. Herein, we summarize key historical discoveries in corneal cell-based regenerative medicine and illustrate the concept of corneal cell therapy for the treatment of refractory corneal epithelial and endothelial diseases.

Corneal Epithelial Stem Cells-Physiology, Pathophysiology and Therapeutic Options

In the human cornea, regeneration of the epithelium is regulated by the stem cell reservoir of the limbus, which is the marginal region of the cornea representing the anatomical and functional border between the corneal and conjunctival epithelium. In support of this concept, extensive limbal damage, e.g., by chemical or thermal injury, inflammation, or surgery, may induce limbal stem cell deficiency (LSCD) leading to vascularization and opacification of the cornea and eventually vision loss. These acquired forms of limbal stem cell deficiency may occur uni- or bilaterally, which is important for the choice of treatment. Moreover, a variety of inherited diseases, such as congenital aniridia or dyskeratosis congenita, are characterized by LSCD typically occurring bilaterally. Several techniques of autologous and allogenic stem cell transplantation have been established. The limbus can be restored by transplantation of whole limbal grafts, small limbal biopsies or by ex vivo-expanded limbal cells. In this review, the physiology of the corneal epithelium, the pathophysiology of LSCD, and the therapeutic options will be presented.