Bioengineered corneas are substitutes for human donor tissue that are designed to treat severe dis-ease affecting ocular surfaces. However,a shortage of candidate seed cells for bioengineering corneas is still a problem. Bone-marrow mesenchymal stem cells (MSCs) are capable of multilineage differen-tiation. Therefore,we determined whether MSCs differentiate into corneal epithelial cells (ECs). We applied three exoteric-microenvironmental systems to induce MSCs to become ECs. Induced MSC were identified by means of morphologic examination,immunocytochemical analysis,and flow cytometry. MSCs grown in one microenvironment had characteristics similar to those of corneal epithelial pro-genitors. Induced MSCs expressed markers for EC,including integrin β1,Cx43,Pax6,and P63. MSCs were successfully induced to become corneal epithelial progenitors. Therefore,the use of MSCs may hold substantial promise for reconstructing the ocular surface after corneal injury.
Protein kinases C (PKCs), a big family including 12 isoenzymes, are divided into three major groups according to the variability of their regulatory domains^1.2 The classical PKCs (cPKC) including PKCα, PKCβI, PKCβ2, and PKC7 need calcium, phosphatidylserine, and diacylglycerol or phorbol esters for full activation. The novel PKCs (nPKC) including PKCδ, PKCε, PKCη, PKCθ, and PKC, do not require calcium for their activation. The third group is the atypical PKCs (aPKC) including PKCζ, PKCλ and PKC~ whose activation depends on phosphatidylserine but not on diacylglycerol, calcium or phorbol esters. The differences in function of specific PKC isoforms are mainly due to their different subcellular localization, activation or inhibition by different stimuli, and transcriptional regulation.
GAO Qian-ying WU Jun-shu WANG Zhi-chong GE Jian HUANG Dan-ping