A study of the expression of functional human coagulation factor IX in keratinocytes using a nonviral vector regulated by K14 promoter

Skin regenerative medicine advancements in the Islamic Republic of Iran: a concise review

In the last decade, the Islamic Republic of Iran has witnessed significant improvement and growth in the field of interdisciplinary medicine and in its translation to patients, including the field of cell and stem cell therapy. The main aim of this report is to highlight various advances in regenerative medicine for skin and dermatology using stem cell technology, and its translation to clinic in the past two decades, in Iranian academic centers, clinical institutes and hospitals. While there have been numerous positive advances in clinical outcomes reported in Iran, there is no comparative analytical information on these studies. Here we present a historical overview of the progress and key advancements seen in skin regeneration in this country, review the research frameworks, regulatory approach and pathways and offer perspectives for the future.

Functions of the Heterologous Intron-Derived Fragments Intra and Extra Factor IX-cDNA Coding Region on the Human Factor IX Expression in HepG2 and Hek-293T Cells

Background

Human FIX (hFIX) gene transfer into hepatocytes has provided a novel approach for treatment of hemophilia B. To obtain an improved expression of hFIX, the functional hFIX-expressing plasmids with appropriate intron-derived fragments which facilitate transcription and promote an efficient 3′-end formation of mRNAs are required.

Objectives

We aim to evaluate the functions of the heterologous intron-derived fragments intra and extra hFIX-cDNA coding region with respect to the hFIX expression in the hepatocytes and kidney cells.

Materials and Methods

HepG2 cells as differentiated hepatocytes and Hek-293T cells as embryonic kidney cells were transfected with the different hFIX-expressing plasmids containing various combinations of the two human beta-globin (hBG) introns within the hFIX-cDNA and Kozak sequence. In the next stage, as a hepatocyte-specific sequence, the rat aldolase B intronic enhancer sequence (rABE), was isolated from the first intron of the rat aldoase B gene and inserted within the upstream CMV promoter (CMVp) and efficacies of the engineered vectors were investigated in the stably-transfected HepG2 cells.

Results

Our data indicate that the intron-less construct and hBG intron-I containing construct are more effective with regard to hFIX expression compared to other constructs in Hek-293 cells. In HepG2 cells, the rABE in combination with CMVp in context of intron-less plasmid induced an increase in total expression of hFIX protein dramatically; ranging from 2.3 to 40 folds increase compared to other constructs. The rABE in combination with CMVp in the hBG intron-I, hBG intron-II, and hBG intron-I,II containing plasmids induced 3.7, 2, and 1.6-fold increase in the total expression of hFIX protein, respectively. The presence of both hBG intronic sequences within the hFIX-cDNA induced a higher secretion level of hFIX than either intron-I or II alone and provided correctly spliced hFIX transcripts in HepG2 and kidney cell lines. The intron-less construct with or without rABE induced the highest hFIX mRNA levels in HepG2 and Hek-293T cells respectively compared to other constructs.

Conclusions

The embryonic kidney cells in addition to the differentiated hepatic cell lines could be successfully targeted by plasmid vectors. The intron-less and hBG intron-I containing plasmids represent a particular interest in producing recombinant hFIX in Hek-293T cells. The synergistic function on the hFIX expression that was achieved by combining the CMVp with the liver-specific rABE would be a useful approach for future designing of the expression cassettes for hepatocyte-mediated gene expression in hemophilia B.

Bioengineering of differentiated hepatocytes with human factor IX-expressing plasmids in vitro

For somatic gene therapy of hemophilia B, hepatocytes as the main cellular host for expression of hFIX are attractive targets. In gene therapy protocols, an efficient expression vector equipped with cis-regulatory elements such as introns is required. With this in mind, hFIX-expressing plasmids equipped with different combinations of 2 human β-globin (hBG) introns inside the hFIX-cDNA and Kozak element were used for bioengineering of HepG2 cells as a model for differentiated hepatocytes and CHO cells a cell line generally used to produce recombinant hFIX (rhFIX). In HepG2 cells, the highest hFIX secretion level occurred for the intron-less plasmid with 8.5 to 53.8- fold increases, while in CHO cells, the hBG intron-I containing plasmid induced highest hFIX secretion level with 2.3 to 14.3-fold increases as compared to other plasmids. The first hBG intron appears to be more effective than the second one in both cell lines. The expression level was further increased upon the inclusion of the Kozak element. The highest hFIX activity was obtained from the cells that carrying the intron-less plasmids with 470 mU/ml and 25 mU/ml for HepG2 and CHO cells respectively. Secretion of active hFIX by all constructs was documented except for hBG intron-II containing construct in both cell lines. HepG2 cells were able to secret higher hFIX levels by 0.6 to 112.2-fold increases with activity by 5.3 to 16.4-fold increases compared to CHO cells transfected with the same constructs. Presence of both hBG intron-I and II inside the hFIX-cDNA provides properly spliced hFIX transcripts in both cell lines. In conclusion, the advantages of hBG introns as attractive cis-regulatory elements to obtain higher expression level of hFIX particularly in CHO cells were demonstrated. Hepatocytes could be effectively bioengineered with the use of plasmid vectors and this strategy may provide a potential in-vitro source of functional hepatocytes for ex-vivo gene therapy of hemophilias and production of rhFIX in vitro.

Genetic modification of bone-marrow mesenchymal stem cells and hematopoietic cells with human coagulation factor IX-expressing plasmids

Ex-vivo gene therapy of hemophilias requires suitable bioreactors for secretion of hFIX into the circulation and stem cells hold great potentials in this regard. Viral vectors are widely manipulated and used to transfer hFIX gene into stem cells. However, little attention has been paid to the manipulation of hFIX transgene itself. Concurrently, the efficacy of such a therapeutic approach depends on determination of which vectors give maximal transgene expression. With this in mind, TF-1 (primary hematopoietic lineage) and rat-bone marrow mesenchymal stem cells (BMSCs) were transfected with five hFIX-expressing plasmids containing different combinations of two human β-globin (hBG) introns inside the hFIX-cDNA and Kozak element and hFIX expression was evaluated by different methods. In BMSCs and TF-1 cells, the highest hFIX level was obtained from the intron-less and hBG intron-I,II containing plasmids respectively. The highest hFIX activity was obtained from the cells that carrying the hBG intron-I,II containing plasmids. BMSCs were able to produce higher hFIX by 1.4 to 4.7-fold increase with activity by 2.4 to 4.4-fold increase compared to TF-1 cells transfected with the same constructs. BMSCs and TF-1 cells could be effectively bioengineered without the use of viral vectors and hFIX minigene containing hBG introns could represent a particular interest in stem cell-based gene therapy of hemophilias.

The design and optimization of RNA trans-splicing molecules for skin cancer therapy

Targeting tumor marker genes by RNA trans-splicing is a promising means to induce tumor cell-specific death. Using a screening system we designed RNA trans-splicing molecules (RTM) specifically binding the pre-mRNA of SLCO1B3, a marker gene in epidermolysis bullosa associated squamous cell carcinoma (EB-SCC). Specific trans-splicing, results in the fusion of the endogenous target mRNA of SLCO1B3 and the coding sequence of the suicide gene, provided by the RTM. SLCO1B3-specific RTMs containing HSV-tk were analyzed regarding their trans-splicing potential in a heterologous context using a SLCO1B3 expressing minigene (SLCO1B3-MG). Expression of the chimeric SLCO1B3-tk was detected by semi-quantitative RT-PCR and Western blot analysis. Cell viability and apoptosis assays confirmed that the RTMs induced suicide gene-mediated apoptosis in SLCO1B3-MG expressing cells. The lead RTM also showed its potential to facilitate a trans-splicing reaction into the endogenous SLCO1B3 pre-mRNA in EB-SCC cells resulting in tk-mediated apoptosis. We assume that the pre-selection of RTMs by our inducible cell-death system accelerates the design of optimal RTMs capable to induce tumor specific cell death in skin cancer cells.