Biomedical subjects

Naoshi Shinozaki

Publications and source records attributed to Naoshi Shinozaki.

8 recordsLinked to original sources

PubMed2006

Long-standing bullous keratopathy is associated with peripheral conjunctivalization and limbal deficiency.

OBJECTIVE: To investigate whether peripheral corneal neovascularization in bullous keratopathy (BK) is due to conjunctivalization, a sign of limbal stem cell deficiency. DESIGN: Observational case-control study. PARTICIPANTS: Sixteen BK patients. METHODS: Patients were divided into 2 groups: BK without peripheral neovascularization [NV(-) group; 5 patients, 5 eyes] and BK with neovascularization [NV(+) group; 11 patients, 13 eyes]. Evidence of conjunctivalization was evaluated by periodic acid-Schiff staining of impression cytology samples from the peripheral vascularized cornea. The 2 groups' durations of disease also were compared. Penetrating keratoplasty (PK) was performed in all 16 cases, and the 2 groups' durations of reepithelialization after PK were compared. MAIN OUTCOME MEASURES: Presence of goblet cells using impression cytology, duration of BK, and duration of postoperative reepithelialization. RESULTS: Goblet cells were found on the peripheral corneal surface in all eyes in the NV(+) group. However, all eyes in the NV(-) group were negative for goblet cells (P<0.0001). Duration of disease was 14.4+/-5.4 months in the NV(-) group and 66.2+/-65.5 months in the NV(+) group (P = 0.030). Duration of postoperative epithelialization was 6.2+/-2.2 days in the NV(-) group and 28.8+/-36.5 days in the NV(+) group (P = 0.046). CONCLUSION: Conjunctivalization of the peripheral cornea and delayed postoperative epithelialization in BK patients with NV suggest the presence of limbal stem cell deficiency in such patients. Patients with long-standing disease were found to be more prone to neovascularization. For this reason, early surgery may lead to a better surgical outcome.

Aged↗

PubMed2005

Serum-free spheroid culture of mouse corneal keratocytes.

PURPOSE: To develop a serum-free mass culture system for mouse keratocytes. METHODS: Corneas of C57BL6/J mice were enzyme digested after the epithelium and endothelium were removed. Stromal cells were cultured in serum-free DMEM/F12 (1:1) containing epidermal growth factor (EGF), fibroblast growth factor 2 (FGF2), and B27 supplement. Primary spheres were dissociated by trypsin and subcultured as suspended secondary spheres. Cells from postnatal day (P)6 to P10 spheres were subcultured onto plastic dishes or type I collagen gels for phenotype analysis. The expression of the keratocyte markers keratocan, aldehyde dehydrogenase (Aldh), and CD34, were analyzed by RT-PCR, and vimentin and alpha-smooth muscle actin (alpha-SMA) were examined by immunocytochemistry. RESULTS: Primary keratocytes formed spheres, which were cultured for over 12 passages. Suspended sphere cells expressed vimentin, keratocan, CD34, and lumican, but were negative for cytokeratin K12 (K12) and Pax6. Sphere cells subcultured on plastic exhibited a dendritic morphology characteristic of keratocytes, and maintained keratocan, Aldh, and CD34 expression in serum-free medium. Sphere cells subcultured with 10% serum became fibroblastic, and expressed alpha-SMA when stimulated by transforming growth factor (TGF)-beta. alpha-SMA-positive cells demonstrated contractile properties on collagen gels, compatible with the myofibroblast phenotype. CONCLUSIONS: The phenotype of mouse keratocytes can be maintained in vitro for more than 12 passages by the serum-free sphere culturing technique.

Animals↗

PubMed2005

[Donor action program].

Recent advances of organ transplantation accelerated shortage of organs. Donor Action Program (DAP) was developed to establish a proper donation process in a hospital using total quality management methodology. It has been demonstrated effective in increasing donation and has been introduced in 23 countries. In Japan preliminary study demonstrated that (1) DAP could be implemented and was likely to increase donation in Japan, (2) Japanese healthcare staffs were likely to underestimate social needs and clinical results of transplantation and to be suspicious about brain death, (3) they had limited knowledge and experience in communicating with family members of the deceased, and their needs for education were not satisfied. In order to implement DAP in Japan, an organization which is responsible for data management and development for educational program should be considered with high priority.

Japan↗

PubMed2004

Efficacy and safety of international donor sharing: a single-center, case-controlled study on corneal transplantation.

BACKGROUND: To overcome the shortage of donor corneas, we are currently using donor corneas supplied by foreign eye banks. This single-center, case-controlled study was conducted to show the efficacy and safety of corneal transplantation using corneas from foreign donors. METHODS: A retrospective, case-controlled comparison of 118 corneal transplants using foreign donor corneas (foreign group) and domestic donor corneas (domestic group) was performed. The two groups were matched according to original disease, age, severity of preoperative neovascularization, and history of previous grafting. Clinical outcome and incidence of postoperative complications were compared between the two groups. RESULTS: The foreign group had a longer preservation-to-operation time than the domestic group, reflecting the longer transportation time. However, the incidence of clear grafts and postoperative complications such as immunologic rejection, infection, and glaucoma was not significantly different between the two groups. CONCLUSIONS: Corneal transplantations using foreign donor corneas are as effective and safe as those using domestic donor corneas, despite the longer preservation time.

Case-Control Studies↗

PubMed2003

Innervated human corneal equivalents as in vitro models for nerve-target cell interactions.

A sensory nerve supply is crucial for optimal tissue function. However, the mechanisms for successful innervation and the signaling pathways between nerves and their target tissue are not fully understood. Engineered tissue substitutes can provide controllable environments in which to study tissue innervation. We have therefore engineered human corneal substitutes that promote nerve in-growth in a pattern similar to in vivo re-innervation. We demonstrate that these nerves (a) are morphologically equivalent to natural corneal nerves; (b) make appropriate contact with target cells; (c) can generate action potentials; (d) respond to chemical and physical stimuli; and (e) play an important role in the overall functioning of the bioengineered tissue. This model can be used for studying the more general topics of nerve ingrowth or regeneration and the interaction between nerves and their target cells and, more specifically, the role of nerves in corneal function. This model could also be used as an in vitro alternative to animals for safety and efficacy testing of chemicals and drugs.

Action Potentials↗

PubMed2003

Collagen-poly(N-isopropylacrylamide)-based membranes for corneal stroma scaffolds.

PURPOSE: To investigate the feasibility of using the biocompatibility of collagen-based blended biomaterials as cell-delivery systems in ocular surface reconstruction in vivo. METHODS: Collagen-based composites that were blended with synthetic acrylamide-based polymers [poly(N-isopropylacrylamide), pNIPAAm] were transplanted into corneal pockets of white rabbits, with a 3-mm epithelial window. Epithelial cells were allowed to migrate onto the polymer. Transplanted eyes were examined daily for up to 30 days, after which animals were killed for histologic examination. Immunohistochemistry was performed for vimentin, alpha-smooth muscle actin (alpha-SMA), CD4, and CD8. Gold-chloride staining was performed to observe neuronal regrowth. Human amniotic membranes (AMs) and sham-operated corneas served as controls. All animals received topical antibiotics (levofloxacin) without the use of steroids or other immunosuppressive agents. RESULTS: The pNIPAAm polymer allowed smooth epithelialization of the cornea, which was similar to the epithelialization observed in sham controls and AM-transplanted eyes. Histology revealed that epithelium overlying the polymer was bundled into several layers, without the orientation observed with AM and sham controls. The polymer gradually thinned and was gradually replaced by host tissue. Vimentin- and alpha-SMA-positive cells were found in stromal pockets up to 1 month following polymer transplantation. These cells were responsible for slight subepithelial haze near the wound edge. CD4- and CD8-positive lymphocytes were also observed in the vicinity of the polymer. Gold-chloride staining showed nerve regrowth in the wound edge after 1 month and subepithelial branches after 3 months. CONCLUSION: Collagen-pNIPAAm blended polymers may be effective as biomaterials to be used in the early stages of lamellar stromal replacement

Acrylic Resins↗

PubMed2002

Clinical application of living-related conjunctival-limbal allograft.

PURPOSE: To report one successful case of conjunctival-limbal allograft for the treatment of a severe ocular surface disorder. METHODS: Interventional case report. A 9-year-old patient suffering from Stevens-Johnson syndrome with total keratinization of the ocular surface of both eyes was treated in the left eye by corneal and conjunctival stem cell transplantation. Oral cyclosporin A and topical autologous serum and corticosteroids were administered. RESULTS: Mucosal epithelial phenotype was maintained in the left eye at most recent examination for more than 3 years after ocular surface reconstruction. CONCLUSION: A total keratinized ocular surface may be treated with the combination of conjunctival and corneal stem cell transplantation.

Child↗

PubMed2002

Artificial human corneas: scaffolds for transplantation and host regeneration.

PURPOSE: To review the development of artificial corneas (prostheses and tissue equivalents) for transplantation, and to provide recent updates on our tissue-engineered replacement corneas. METHODS: Modified natural polymers and synthetic polymers were screened for their potential to replace damaged portions of the human cornea or the entire corneal thickness. These polymers, combined with cells derived from each of the three main corneal layers or stem cells, were used to develop artificial corneas. Functional testing was performed in vitro. Trials of biocompatibility and immune and inflammatory reactions were performed by implanting the most promising polymers into rabbit corneas. RESULTS: Collagen-based biopolymers, combined with synthetic crosslinkers or copolymers, formed effective scaffolds for developing prototype artificial corneas that could be used as tissue replacements in the future. We have previously developed an artificial cornea that mimicked key morphologic and functional properties of the human cornea. The addition of synthetic polymers increased its toughness as it retained transparency and low light scattering, making the matrix scaffold more suitable for transplantation. These new composites were implanted into rabbits without causing any acute inflammation or immune response. We have also fabricated full-thickness composites that can be fully sutured. However, the long-term effects of these artificial corneas need to be evaluated. CONCLUSIONS: Novel tissue-engineered corneas that comprise composites of natural and synthetic biopolymers together with corneal cell lines or stem cells will, in the future, replace portions of the cornea that are damaged. Our results provide a basis for the development of both implantable temporary and permanent corneal replacements.

Animals↗