Liu Xin, Tseng Scheffer C G, Zhang Ming-Chang, Chen Szu-Yu, Tighe Sean, Lu Wen-Juan, Zhu Ying-Ting
a Department of Ophthalmology; Union Hospital; Tongji Medical College ; Huazhong University of Science and Technology ; Wuhan , China.
Cell Cycle. 2015;14(8):1197-206. doi: 10.1080/15384101.2015.1013667.
Human corneal endothelial cells (HCECs) responsible for corneal transparency have limited proliferative capacity in vivo because of "contact-inhibition." This feature has hampered the ability to engineer HCECs for transplantation. Previously we have reported an in vitro model of HCECs in which contact inhibition was re-established at Day 21, even though cell junction and cell matrix interaction were not perturbed during isolation. Herein, we observe that such HCEC monolayers continue to expand and retain a normal phenotype for 2 more weeks if cultured in a leukemia inhibitory factor (LIF)-containing serum-free medium. Such expansion is accompanied initially by upregulation of Cyclin E2 colocalized with nuclear translocation of phosphorylated retinoblastoma tumor suppressor (p-Rb) at Day 21 followed by a delay in contact inhibition through activation of LIF-Janus kinase1 (JAK1)-signal transducer and activator of transcription 3 (STAT3) signaling at Day 35. The LIF-JAK1-STAT3 signaling is coupled with upregulation of E2F2 colocalized with nuclear p-Rb and with concomitant downregulation of p16(INK4a), of which upregulation is linked to senescence. Hence, activation of LIF-JAK1-STAT3 signaling to delay contact inhibition can be used as another strategy to facilitate engineering of HCEC grafts to solve the unmet global shortage of corneal grafts.
负责角膜透明度的人角膜内皮细胞(HCECs)在体内因“接触抑制”而增殖能力有限。这一特性阻碍了用于移植的HCECs工程化的能力。此前我们报道了一种HCECs的体外模型,其中在第21天重新建立了接触抑制,尽管在分离过程中细胞连接和细胞基质相互作用未受干扰。在此,我们观察到,如果在含有白血病抑制因子(LIF)的无血清培养基中培养,此类HCEC单层细胞会继续扩增并在接下来的2周内保持正常表型。这种扩增最初伴随着第21天细胞周期蛋白E2的上调,其与磷酸化视网膜母细胞瘤肿瘤抑制因子(p-Rb)的核转位共定位,随后在第35天通过激活LIF- Janus激酶1(JAK1)-信号转导和转录激活因子3(STAT3)信号通路延迟接触抑制。LIF-JAK1-STAT3信号通路与与核p-Rb共定位的E2F2的上调以及p16(INK4a)的下调相关联,其中p16(INK4a)的上调与衰老有关。因此,激活LIF-JAK1-STAT3信号通路以延迟接触抑制可作为另一种策略来促进HCEC移植物的工程化,以解决全球角膜移植物供不应求的问题。