The primary Syrian hamster embryo(SHE) cells were used to study the oncogenic transformation by ￣(238)pu α particles or X-rays alone or in combination with a chemical promoter phorbol ester.Survival curves of SHE ce...The primary Syrian hamster embryo(SHE) cells were used to study the oncogenic transformation by ￣(238)pu α particles or X-rays alone or in combination with a chemical promoter phorbol ester.Survival curves of SHE cells following exposure to α-particles or X-rays were fitted to single-or multi-target models,respectively. Model parameters were: Do = 0. 55 Gy. n = 1 for α particles 4 Do = 1.44 Gy. Dq = 3.0 Gy. n=7.7 for X-rays.Incidence of α particles or X-rays induced cell transformation was dose-dependant.α particles were more efficient in inducing cell transformation than that of X-rays. The enhancement of SHE cell transformation by phorbol 12-myristate 13-acetate(PMA) following exposure to α particles of 0. 25-1. 00 Gy was observed.展开更多
Objective: We established a transplantation tumor model of human osteosarcoma in chick embryo, studied its morphological and biological characteristics, and observed its dynamic process of angiogenesis induction so th...Objective: We established a transplantation tumor model of human osteosarcoma in chick embryo, studied its morphological and biological characteristics, and observed its dynamic process of angiogenesis induction so that a simple and practical model can be provided for studying osteosarcoma. Methods: Human osteosarcoma cells at different concentrations were inoculated in chorioallantoic membrane (CAM) of chick embryos at different embryonic ages to observe the factors affecting the survival of the transplanted osteosarcoma in chick embryo, growth characteristics of the transplantation tumor, and the morphological characteristics and biological characteristics of the transplantation tumor. Results: The transplantation tumor model of human osteosarcoma in chick embryo was successfully established. It was found that the transplantation tumor was easy to grow and it showed strong angiogenesis-inducing effects. Under the light microscope, the transplantation tumor showed a similar tissue structure to human osteosarcoma. Conclusion: It is feasible to establish a transplantation tumor model of human osteosarcoma in chick embryo. The model can be easily duplicated with a simple operation, which provides a useful animal model for studying osteosarcoma.展开更多
Two new types of lentiviral vectors expressing a reporter transgene encoding either firefly luciferase （fLuc） for bioluminescence imaging or the HSV1 thymidine kinase （HSV1-TK） for radiopharmaceutical-based imagin...Two new types of lentiviral vectors expressing a reporter transgene encoding either firefly luciferase （fLuc） for bioluminescence imaging or the HSV1 thymidine kinase （HSV1-TK） for radiopharmaceutical-based imaging were constructed to monitor human embryonic stem cell （hESC） engraftment and proliferation in live mice after trans- plantation. The constitutive expression of either transgene did not alter the properties of hESCs in the culture. We next monitored the formation of teratomas in SCID mice to test （1） whether the gene-modified hESCs maintain their developmental pluripotency, and （2） whether sustained reporter gene expression allows noninvasive, whole-body imaging of hESC derivatives in a live mouse model. We observed teratoma formation from both types of gene-modified cells as well as wild-type hESCs 2-4 months after inoculation. Using an optical imaging system, bioluminescence from the fLuc-transduced hESCs was easily detected in mice bearing teratomas long before palpable tumors could be detected. To develop a noninvasive imaging method more readily translatable to the clinic, we also utilized HSV1-TK and its specific substrate, 1-（2＇-deoxy-2＇-fluoro-β-D-arabinofuranosyl）-5-[^125I]iodouracil（[^125I]FIAU）, as a reporter/ probe pair. After systemic administration, [^125I]FIAU is phosphorylated only by the transgene-encoded HSV1-TK enzyme and retained within transduced （and transplanted） cells, allowing sensitive and quantitative imaging by single-photon emission computed tomography. Noninvasive imaging methods such as these may enable us to monitor the presence and distribution of transplanted human stem cells repetitively within live recipients over a long term through the expression of a reporter gene.展开更多
microRNAs （miRNAs） constitute a unique class of endogenous small non-coding RNAs that regulate gene expression post-transcriptionally. Studies over the past decade have uncovered a r^curring paradigm in which miRNAs...microRNAs （miRNAs） constitute a unique class of endogenous small non-coding RNAs that regulate gene expression post-transcriptionally. Studies over the past decade have uncovered a r^curring paradigm in which miRNAs are key regulators of cellular behavior under various physiological and pathological conditions. Most surprising is the recent observation that miRNAs have emerged as competent players in somatic cell reprogramming, suggesting an especially significant role for these small RNAs in cell fate settings. Here, we discuss the possible mechanisms underlying miRNA-mediated cell programming （i.e., the development and differentiation of embryonic stem cells） and reprogramming （i.e., turning somatic cells into pluripo- tent stem cells or other lineages）, and provide a ＂Helm＂ model of miRNAs in cell fate decision and conversion.展开更多
文摘The primary Syrian hamster embryo(SHE) cells were used to study the oncogenic transformation by ￣(238)pu α particles or X-rays alone or in combination with a chemical promoter phorbol ester.Survival curves of SHE cells following exposure to α-particles or X-rays were fitted to single-or multi-target models,respectively. Model parameters were: Do = 0. 55 Gy. n = 1 for α particles 4 Do = 1.44 Gy. Dq = 3.0 Gy. n=7.7 for X-rays.Incidence of α particles or X-rays induced cell transformation was dose-dependant.α particles were more efficient in inducing cell transformation than that of X-rays. The enhancement of SHE cell transformation by phorbol 12-myristate 13-acetate(PMA) following exposure to α particles of 0. 25-1. 00 Gy was observed.
文摘Objective: We established a transplantation tumor model of human osteosarcoma in chick embryo, studied its morphological and biological characteristics, and observed its dynamic process of angiogenesis induction so that a simple and practical model can be provided for studying osteosarcoma. Methods: Human osteosarcoma cells at different concentrations were inoculated in chorioallantoic membrane (CAM) of chick embryos at different embryonic ages to observe the factors affecting the survival of the transplanted osteosarcoma in chick embryo, growth characteristics of the transplantation tumor, and the morphological characteristics and biological characteristics of the transplantation tumor. Results: The transplantation tumor model of human osteosarcoma in chick embryo was successfully established. It was found that the transplantation tumor was easy to grow and it showed strong angiogenesis-inducing effects. Under the light microscope, the transplantation tumor showed a similar tissue structure to human osteosarcoma. Conclusion: It is feasible to establish a transplantation tumor model of human osteosarcoma in chick embryo. The model can be easily duplicated with a simple operation, which provides a useful animal model for studying osteosarcoma.
文摘Two new types of lentiviral vectors expressing a reporter transgene encoding either firefly luciferase （fLuc） for bioluminescence imaging or the HSV1 thymidine kinase （HSV1-TK） for radiopharmaceutical-based imaging were constructed to monitor human embryonic stem cell （hESC） engraftment and proliferation in live mice after trans- plantation. The constitutive expression of either transgene did not alter the properties of hESCs in the culture. We next monitored the formation of teratomas in SCID mice to test （1） whether the gene-modified hESCs maintain their developmental pluripotency, and （2） whether sustained reporter gene expression allows noninvasive, whole-body imaging of hESC derivatives in a live mouse model. We observed teratoma formation from both types of gene-modified cells as well as wild-type hESCs 2-4 months after inoculation. Using an optical imaging system, bioluminescence from the fLuc-transduced hESCs was easily detected in mice bearing teratomas long before palpable tumors could be detected. To develop a noninvasive imaging method more readily translatable to the clinic, we also utilized HSV1-TK and its specific substrate, 1-（2＇-deoxy-2＇-fluoro-β-D-arabinofuranosyl）-5-[^125I]iodouracil（[^125I]FIAU）, as a reporter/ probe pair. After systemic administration, [^125I]FIAU is phosphorylated only by the transgene-encoded HSV1-TK enzyme and retained within transduced （and transplanted） cells, allowing sensitive and quantitative imaging by single-photon emission computed tomography. Noninvasive imaging methods such as these may enable us to monitor the presence and distribution of transplanted human stem cells repetitively within live recipients over a long term through the expression of a reporter gene.
基金supported by the National Natural Science Foundation of China(31200593,31230042,81070589)the Guangdong Natural Science Foundation(S2011040001760)+1 种基金the Fundamental Research Funds for the Central Universities(13lgpy40)the National Basic Research Program of China(2011CB811300)
文摘microRNAs （miRNAs） constitute a unique class of endogenous small non-coding RNAs that regulate gene expression post-transcriptionally. Studies over the past decade have uncovered a r^curring paradigm in which miRNAs are key regulators of cellular behavior under various physiological and pathological conditions. Most surprising is the recent observation that miRNAs have emerged as competent players in somatic cell reprogramming, suggesting an especially significant role for these small RNAs in cell fate settings. Here, we discuss the possible mechanisms underlying miRNA-mediated cell programming （i.e., the development and differentiation of embryonic stem cells） and reprogramming （i.e., turning somatic cells into pluripo- tent stem cells or other lineages）, and provide a ＂Helm＂ model of miRNAs in cell fate decision and conversion.
