| ObjectivesBone marrow mesenchymal stem Cells ( MSCs) are adult stem cells, which locate in adult mammal bone marrow. MSCs are imbued with potential for self -renewal and can proliferate extensively. A variety of " markers" have been suggested to identify MSCs, such as SH - 2, CD29, CD44, CD71, CD90, CD106, CD120a,Stro - 1. While CD45, CD34, CD14, markers of hematopoietic stem cells (HSCs) are negative. MSCs are considered to have the potential to differentiate into other tissues and cell lines. MSCs could differentiate into bone tissue , cartilage tissue, nerve tissue, muscle tissue and adipose tissue and so on.The cornea provides the eye with protection and the refractive properties essential for visual acuity. As a result of normal wear and tear or in response to injury, corneal epithelial cells must be renewed. Corneal epithelial stem cells ( CESCs) are the ultimate source of regeneration of the entire corneal epithelium under both normal and injuried states. Following injury to the comeal epithelium , the CESCs divide to produce daughter transient amplifying cells that proliferate , migrate, and differentiate to replace lost cells and maintain a healthy ocular surface. A number of markers have been found in an attempt to identify stem cells; however, definite stem cell identification remains elusive. CK3,CK19 are often used to identify CESCs.However, some pathological conditions or injuries lead to partial or total comeal epithelial stem cell deficiency at the limbus, causing the failure of the normal mechanism of comeal epithelial cell replacement. When comeal epithelial stem cell deficiency happens, it will result in conjunctival invasion, vascular-ization, and persistent epithelial defect, lead to corneal meltdown and cause pain, poor vision, and even blindness. A variety of therapeutic strategies aiming at reversing stem cell deficiency are currently used with the knowledge of CESCs biology in the corneal epithelium and CESCs deficiency. These strategies include amniotic grafts, keratolimbal autografts and keratolimbal allografts. All these options could not avoid the questions of immunological rejection and insufficient donors.And because of its sufficient source, convenient access, safety, and main-tainance of the highest proliferative capacity, avoiding immunological rejection, MSCs might become much more important in the field of tissue engineering and wound repair. However the differentiation mechanism of the MSCs, the pheno-type and function of the cells after differentiation remain unclear.To investigate MSCs differentiation in response to corneal injury, we developed an ex vivo model of CESCs repair by coculturing MSCs with heat - shocked CESCs. We hope this article will attribute to the use of MSCs in ophthalmology.Methods1. Human MSCs were extracted from healthy adult human marrow and cultured under 37°C in wet air including 5ml/L CO2. Expression of CD34NCD44 were detected with immunocytochemical method and flow cytometry. Then MSCs were transfected with gene encoding enhanced green fluorescent protein ( EGFP) by a retroviral vector.2. Human CESCs were obtained from human corneal biopsy specimen with limbus digested by Dispase II and cultured under 371 in wet air including 5ml/L CO2. Expression of CK3NCK19 were detected with immunocytochemical method.3. Then we developed a heat - shocked model of CESCs in vitro, and cocul-tured with EGFP+ MSCs. The results were observed by fluorescence microscope and immunocytochemistry of CK19 after 2 weeks. |
PDF Full Text Request