Gene therapy: current status

Growth inhibition of human glioma cells by transfection-induced P21 and its effects on telomerase activity

The aim of this study is to investigate the effect of the p21 gene transfection on the growth of cultured human glioma cell lines, and analyze the telomerase activity, and detection of telomerase components in p21 transfectant. The p21 gene was transfected into human glioma cell lines, U251MG and T98G with our novel liposome. The cell growth was assessed by counting the number of trypan blue-excluding cells in a hemocytometer and flow cytometry analysis. The expression of P21 protein and its mRNA were examined by Western and Northern blot analysis. The telomerase activity was assayed by TRAP (telomerase repeat amplification protocol)/TRAP-HPA (hybridization protection assay) method qualitatively and quantitatively. The length of telomere was measured by Southern blot analysis. The expression of telomerase components (hTERT, hTERC and TEP1) were examined by RT-PCR (reverse transcriptase-polymerase chain reaction). The p21 transfectant demonstrated the expression of P21 protein and its mRNA. The p21 transfection of human glioma cells results in growth inhibition and G0/G1 arrest. The p21 transfectant revealed a decrease of telomerase activity and hTERT expression as compared with control cells. These results suggest that p21 transfection induces G0/G1 arrest in human glioma cells which associates with the reduction in the telomerase activity and hTERT expression.

Non-viral gene therapy

Gene therapy is a medical/surgical intervention currently being developed, in which genes are introduced into cells in order to treat or cure a wide variety of human diseases. The field has evolved over the past four decades, with most experimental gene-therapy studies based on the use of viruses to deliver the genes of therapeutic interest. More recently, a large number of non-viral approaches to gene therapy have emerged, yielding promising pre-clinical results, and which are currently being evaluated in early stage clinical trials.

Growth inhibition of intracerebral rat glioma by transfection-induced human interferon-beta

In our previous study on liposome-mediated transfection of the human interferon-beta (HuIFN-beta) gene into subcutaneously implanted human gliomas in nude mice, we found that HuIFN-beta was produced and secreted by the tumor cells and that the growth of solid tumors was completely inhibited. The present study investigated the growth-inhibitory effect of liposomes containing the HuIFN-beta gene inserted into a vector (pSV2IFN-beta) on T9 rat glioma implanted into the brains of rats. Tumor cells and liposomes containing pSV2IFN-beta or other additives were simultaneously injected into the brains of rats. HuIFN-beta was detected in solid gliomas growing in the brains of rats injected with liposomes and magnetic resonance imaging (MRI) showed that tumor growth was inhibited. In addition, the latent period until the appearance of neurological symptoms was significantly prolonged in rats treated with liposomes containing pSV2IFN-beta. However, the survival time of the treated rats was not significantly increased.

Liposomes for the transformation of eukaryotic cells

Gene therapy of human disease is a method of treatment under active development. DNA-loaded liposomes exhibit great promise for use in this field. Liposome-based transfection vectors have many inherent advantages that will likely lead to their wide in vivo use. Vectors with low toxicity and a high degree of targetability can now be easily prepared. These vectors are also free of the length constraints governing retroviral vectors. In this review we discuss recent developments in the use of liposomes for transfection of eukaryotic cells.

High efficiency gene transfection by electroporation using a radio-frequency electric field

In order to develop a safe and effective way to introduce exogenous genes into cells, we have experimented with a new method of electroporation which uses a radio-frequency (RF) electric field to permeabilize the cell membrane. This RF method has several advantages over the conventional electroporation method which uses a direct current (DC) field. We have shown that the RF electroporation method can be used to introduce marker genes into a wide variety of cell lines, including COS-M6, CV-1, CHO, 3T3 and hepatocytes, and is able to increase substantially the efficiency of gene transfection. (For example, the amount of DNA required for transfecting two million COS-M6 cells can be as low as 0.1 microgram). The transfection efficiency is shown to be affected by a number of factors, including cell type, field strength, pulse protocol and medium buffer. Because of its wide range of applications, high transfection efficiency and lack of harmful side-effect, the RF electroporation method would be particularly useful for introducing genes into human cells for gene therapy.

Environmental carcinogenesis and biotechnology

Numerous environmental and host factors, some of which are known and some unknown, contribute to cancer development. While data and studies abound, our current understanding of the relation between cancer and the environment is still very limited. Understanding environmental carcinogenesis is critical to its effective management. Biotechnology has revolutionalized the study of biological and biomedical sciences. This minireview provides an overview of environmental carcinogenesis with emphasis on the contributions and prospects of biotechnology in advancing an understanding of environmental carcinogenesis for its prevention and intervention.

Progress toward human gene therapy

Current therapies for most human genetic diseases are inadequate. In response to the need for effective treatments, modern molecular genetics is providing tools for an unprecedented new approach to disease treatment through an attack directly on mutant genes. Recent results with several target organs and gene transfer techniques have led to broad medical and scientific acceptance of the feasibility of this "gene therapy" concept for disorders of the bone marrow, liver, and central nervous system; some kinds of cancer; and deficiencies of circulating enzymes, hormones, and coagulation factors. The most well-developed models involve alteration of mutant target genes by gene transfer with recombinant pathogenic viruses in order to express new genetic information and to correct disease phenotypes--the conversion of the swords of pathology into the plowshares of therapy.