Corneal transplantation is the most effective treatment for corneal blindness at present,but the shortage of cornea donation and graft rejection are the serious obstacles for its broad application.Construction of tissueengineered corneal substitutes with good biocompatibility and normal biological function is emerging as a potential approach to overcome the shortages of donor corneas,and which will be a potential source of corneal grafts for corneal transplantation.With the development in the technology of biomaterials,cell culture and tissue engineering,the field of corneal tissue engineering has made great strides in scaffolds,seed cells and three-dimensional reconstruction recently,and also start to be used in clinical practice.The tissue-engineered cornea with good mechanical property,light transmittance and biocompatibility may serve as an ideal candidate in the treatment of corneal diseases.Amniotic membrane,acellular porcine corneal matrix,collagen,silk fibroin,and chitosan are frequently-used scaffold for cornea tissue engineering.Currently,immortalized and primary cultured corneal cells,embryonic stem cells,and adult stem cells have been reported to be used as seed cells in the construction of tissue-engineered cornea.This chapter reviewed the advances made in tissue-engineered cornea,including scaffolds,seed cells,and three-dimensional reconstruction.

Objective:To retrospective analyze the epidemiology, clinical characteristics, treatment and prognosis in patients with coronavirus disease 2019 (COVID-19).Methods:A total of 278 patients with COVID-19 admitted to Guangzhou Eighth People′s Hospital from January 20 to February 10, 2020 were selected. The general demographic data, epidemiological data, clinical symptoms, laboratory examinations, lung CT imaging, treatment and prognosis were analyzed.Results:There were 130 male patients (46.8%) and 148 females (53.2%) with age (48.1±17.0) years and 88.8% patients between 20-69 years. Two hundred and thirty-six (84.9%) patients had comorbidities. Two hundred and eleven cases (75.9%) were common type. The in-hospital mortality was 0.4% (1/278). The majority (201, 72.3%) were imported cases mainly from Wuhan (89, 44.3%). The most common clinical manifestations were fever (70.9%) and dry cough (61.5%). In some patients, hemoglobin (10.4%), platelets (12.6%) and albumin (55.4%) were lower than the normal range. Other biochemical tests according to liver and function were normal, while lactic dehydrogenase (LDH) was elevated in 61 patients (21.9%), creatine kinase increased in 26 patients (9.4%). Prolonged activated partial thromboplastin time (APTT) was seen in 52 patients (18.7%), D-dimer higher than normal in 140 patients (50.4%), while 117 patients (42.1%) had elevated high-sensitivity C-reactive protein. Typical CT manifestations included single or multiple ground glass shadows especially in lung periphery in early disease which infiltrated and enlarged during progressive stage. Diffuse consolidation with multiple patchy density in severe/critical cases and even "white lung" presented in a few patients. Two hundred and forty-two patients (87.1%) received one or more antiviral agents, 242 (87.1%) combined with antibacterials, 191 (68.7%) with oxygen therapy. There were 198 patients (71.2%) treated with traditional Chinese medicine.Conclusions:COVID-19 could attack patients in all ages with majority of common type and low mortality rate. Clinical manifestations involve multiple organs or systems. Progression of the disease results in critical status which should be paid much attention.

AIM:To identify transcriptional differences between the ocular surface ectoderm(OSE)and surface ectoderm(SE)using RNA-seq, and elucidate the OSE transcriptome landscape and the regulatory networks involved in its development.METHODS:OSE and SE cells were differentiated from human embryonic stem(hES)cells. Differentially expressed genes(DEGs)between OSE and SE were analyzed using RNA-seq. Based on the DEGs, we performed gene ontology(GO)analysis, Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analysis, and protein-protein interaction(PPI)network analysis. Transcription factors(TFs)and hub genes were screened. Subsequently, TF-gene and TF-miRNA regulatory networks were constructed using the NetworkAnalyst platform.RESULTS:A total of 4 182 DEGs were detected between OSE and SE cells, with 2 771 up-regulated and 1 411 down-regulated genes in OSE cells. GO-BP analysis revealed that up-regulated genes in OSE were enriched in the regulation of ion transmembrane transport, axon development, and modulation of chemical synaptic transmission. Down-regulated genes were primarily involved in nuclear division, chromosome segregation, and regulation of cell cycle phase transition. KEGG analysis indicated that up-regulated genes in OSE cells were enriched in signaling pathways such as cocaine addiction, axon guidance, and amphetamine addiction, while down-regulated genes were enriched in proteoglycans in cancer, ECM-receptor interaction, protein digestion and absorption, and cytokine-cytokine receptor interaction. Additionally, compared with SE, 204 TFs(including FOS, EGR1, POU5F1, SOX2, and PAX6)were up-regulated, and 80 TFs(including HAND2, HOXB6, HOXB5, HOXA5, and HOXB8)were down-regulated in OSE cells. Furthermore, we identified 6 up-regulated and 9 down-regulated hub genes in OSE cells, and constructed TF-gene and TF-miRNA regulatory networks based on these hub genes.CONCLUSIONS:The transcriptome characteristics of OSE and SE cells were elucidated through RNA-seq analysis. These findings may provide a novel insight for studies on the development and in vitro directed induction of OSE and corneal epithelial cells.