The roles of LMO4 in endothelial cells differentiation and angiogenesis from murine embryonic stem cells / 安徽医科大学学报

Objective @#To examine the role of LMO4 in the regulation of endothelial cell differentiation and angio- genesis in murine embryonic stem cells (mESC) ．@*Methods @#Mouse Lmo4 cDNA was obtained from MEL cells by using the reverse transcription-polymerase chain reaction (RT-PCR) and subcloned into the expression vector pFG to generate the pFLG ，in which contained Flk-1 promoter to drive Lmo4 expresses in only FLK-1 + cells．The mESC were transfected with pFG or pFLG plasmids and subsequently screened with geneticin ( G418) to produce cell clones． These cell clones were named mESC /pFG and mESC /pFLG ，respectively． The mESC /pFG and mESC /pFLG were cultured in the differentiation medium for either 4 days or 10 days to generate embryoid bodies (EB) ．The 10-day embryoid bodies ( 10 d-EBs) carrying the pFG and pFLG vectors were subsequently stimulated to generate the blast-colony forming cells (BL-CFC) ，which indicated the presence of hemangioblasts．The endo- thelial cell sprouting analysis was performed by using 10 d-EBs．The expression of the interest genes was detected by using qualitative RT-PCR or Western blot analysis. @*Results @#The pFLG expression vector was successfully con- structed through PCR identification．The mESC /pFG and mESC /pFLG cells were obtained after transfected with the pFG or pFLG vectors and selected by G418．The cells spontaneously differentiate to generate EBs，in which some green fluoresce cells were present．Western blot analysis showed that a significant increase in LMO4 expression in both 4 d-EB and 10 d-EB when compared to mESC．BL-CFC analysis showed that the 4 d-EB/ pFLG had a higher cloning efficiency ( 7. 70% ± 1. 27% ) ，comparing with that of the 4 d-EB/ pFG ( 1. 15% ± 0. 48% ) ( P = 0. 021) ．Quantitative RT-PCR results showed that the expression of Flk-1，C-kit，Tie-2 and Ve-cad genes in 10 d- EBs /pFLG increased more than 2-fold compared to 10 d-EBs /pFG．The endothelial cell sprouting analysis result showed a significant increase in the number and length of new blood vessels in 10 d-EB/ pFLG compared to 10 d- EB/ pFG (P＜0. 05) ．@*Conclusion @#Overexpression of LMO4 promotes hemangioblast differentiation from mESC， and benefits for endothelial cell differentiation and angiogenesis.

Directing Human Embryonic Stem Cells towards Functional Endothelial Cells Easily and without Purification

Hemangioblasts or blood islands only arise in early development thereby the sources to obtain these bi-potential cells are limited. While previous studies have isolated both lineages in vitro through the hemangioblast, derivation efficiency was rather low due to cellular damage attributed by enzyme usage and fluorescent activated cell sorting (FACS). This study focused on avoiding the use of damaging factors in the derivation of endothelial cells (ECs). Single cell H9-human embryonic stem cells (hESCs) were obtained by using a mild dissociation protocol then human embryoid body (hEB) formation was performed under hemangioblast differentiation conditions. The hEBs were subjected to a two-stage cytokine treatment procedure. Subsequent culture of the adhesive cells in day 4 hEBs gave arise to a seemingly pure population of ECs. The hESC-derived ECs were characterized by identifying signature endothelial gene and protein markers as well as testing for in vitro functionality. Furthermore, in vivo functionality was also confirmed by transplanting the cells in hindlimb ischemic murine models. We demonstrate that the genetic change required for EC derivation precedes blast colony formation. Furthermore, cell damage was prevented by abating enzyme usage and FACS, resulting in a high yield of ECs upon adhesion. Under this method, confluent cultures of ECs were obtainable 4 days after hEB formation which is significantly faster than previous protocols.

Effects of erythropoietin on peripheral blood endothelial progenitor cells from rats with chronic kidney disease / 中华肾脏病杂志

Objective To investigate the effects of erythropoietin (EPO) on the number and function of peripheral blood endothelial progenitor cells (EPCs) from rats with chronic renal failure (CRF). Methods The model of chronic renal failure was established by a two-stage 5/6nephrectomy procedure in rats. Experimental rats were randomly divided into four groups (n =7,respectively): sham operation group, CRF group, CRF rats treated with 30 U/kg EPO (low-dosage group) and with 50 U/kg EPO (high-dosage group). CRF rats were given EPO by hypodermic injection for 6 weeks, then EPCs were isolated by density gradient centrifugation from peripheral blood mononuclear cells. The ability of cell proliferation, adhesion and vasculogenesis in vitro was further observed. Results Compared to sham operation group, the ability of cell proliferation,adhesion and vasculogenesis in vitro in CRF rats was remarkably decreased (P＜0.05, respectively).Such ability was promoted significantly in dose-dependent manner by EPO treatment (P＜0.05,respectively). Conclusion EPO can improve the number and ability of endothelial progenitor cells from rats with chronic renal failure.

Research progress in differentiation of embryonic stem cells to hemangioblast / 国际生物医学工程杂志

The concept of hemangioblast was proposed a century ago. The existence of hemangioblasts has been demonstrated recently in vitro by differentiation of mouse and human embryonic stem (ES) cell into em-bryoid bodies(EBs). In the developing embryo, a common progenitor, termed "hemangioblast", generates both hematopoietic and endothelial cell lineages. The in vitro differentiation of embryonic stem cells to hemangioblast is a powerful approach for studying the commitment of the hematopoietic and endothelial lineages. This review will summarize recent development in the studies on hemangioblast.