Application of efficient and specific gene transfer systems and organ culture techniques for the elucidation of mechanisms of epithelial-mesenchymal interaction in the developing gut

BMP2 inhibits cell proliferation by downregulating EZH2 in gastric cancer

Gastric cancer is among the most common gastrointestinal malignancies. Recent studies have suggested that bone morphogenetic protein-2 (BMP2) is related to the development and progression of various cancers. Meanwhile, evidence suggests that BMP2 might lead to epigenetic changes in gastric cancer. Thus, we investigated whether BMP2 plays a role in the development of gastric cancer via epigenetic regulation. Cell viability, colony formation, and cell cycle assays were performed to assess the effect of recombinant human BMP2 (rhBMP2) in gastric cancer cells. LDN-193189 and Noggins were used as antagonists of the canonical BMP-SMAD signaling pathway. The protein levels were determined using a western blot analysis. Lentiviral vectors with EZH2 shRNA or EZH2 overexpression were used to mediate the role of EZH2 and the relationship between BMP2 and EZH2 in gastric cancer. We found that rhBMP2 inhibits cell proliferation by arresting the cell cycle in HGC-27 and SNU-216 gastric cancer cells. Neither LDN-193189 nor Noggins, antagonists of the canonical BMP-SMAD signaling pathway, can reverse the effect of rhBMP2 on gastric cancer. Molecularly, rhBMP2 downregulates the expression of EZH2 and H3K27me3, leading to increases in P16 and P21 and decreases in CDK2, CDK4, and CDK6. Altogether, in this study, we demonstrate that BMP2 serves as a tumor suppressor in gastric cancer cells by downregulating EZH2 and H3K27me3 through the non-SMAD BMP pathway, suggesting that BMP2 might be a new therapeutic target for gastric cancer treatment. Abbreviations: BMP: bone morphogenetic protein; TGF-β: transforming growth factor-beta; EZH2: enhancer of zeste homolog 2; H3K27me3: trimethylation histone H3 lysine 27; HRECs: human retinal endothelial cells; PcG: polycomb group; PRC: polycomb repressive complexes.

Changes in phenotype and differentiation potential of human mesenchymal stem cells aging in vitro

Background

Adult mesenchymal stem cells (MSCs) hold great promise for regenerative medicine because of their self-renewal, multipotency, and trophic and immunosuppressive effects. Due to the rareness and high heterogeneity of freshly isolated MSCs, extensive in-vitro passage is required to expand their populations prior to clinical use; however, senescence usually accompanies and can potentially affect MSC characteristics and functionality. Therefore, a thorough characterization of the variations in phenotype and differentiation potential of in-vitro aging MSCs must be sought.

Methods

Human bone marrow-derived MSCs were passaged in vitro and cultivated with either DMEM-based or αMEM-based expansion media. Cells were prepared for subculture every 10 days up to passage 8 and were analyzed for cell morphology, proliferative capacity, and surface marker expression at the end of each passage. The gene expression profile and adipogenic and osteogenic differentiation capability of MSCs at early (passage 4) and late (passage 8) passages were also evaluated.

Results

In-vitro aging MSCs gradually lost the typical fibroblast-like spindle shape, leading to elevated morphological abnormality and inhomogeneity. While the DMEM-based expansion medium better facilitated MSC proliferation in the early passages, the cell population doubling rate reduced over time in both DMEM and αMEM groups. CD146 expression decreased with increasing passage number only when MSCs were cultured under the DMEM-based condition. Senescence also resulted in MSCs with genetic instability, which was further regulated by the medium recipe. Regardless of the expansion condition, MSCs at both passages 4 and 8 could differentiate into adipocyte-like cells whereas osteogenesis of aged MSCs was significantly compromised. For osteogenic induction, use of the αMEM-based expansion medium yielded longer osteogenesis and better quality.

Conclusions

Human MSCs subjected to extensive in-vitro passage can undergo morphological, phenotypic, and genetic changes. These properties are also modulated by the medium composition employed to expand the cell populations. In addition, adipogenic potential may be better preserved over osteogenesis in aged MSCs, suggesting that MSCs at early passages must be used for osteogenic differentiation. The current study presents valuable information for future basic science research and clinical applications leading to the development of novel MSC-based therapeutic strategies for different diseases.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0876-3) contains supplementary material, which is available to authorized users.

Primary Cell Culture Systems for Human Thyroid Studies

BACKGROUND

Cell models are key instruments for in vitro studies of the thyroid. Permanent thyroid cell lines that are widely used in laboratory research typically originate from tumors. For many purposes, it is desirable to compare tumor cells with cells originating from normal tissue. However, such cultures grow slowly, have a highly limited life-span, and are known to lose their thyroid characteristics. The aim of the present study was to type coding and noncoding thyroid markers in different culture systems in an attempt to determine the optimal conditions for in vitro experimentation.

METHODS

Human primary thyroid cells were isolated from histologically non-tumorous tissues. Two alternative media (6H and h7H) were used. The morphology and behavior of the ensuing monolayer (two-dimensional) cultures was monitored by microscopy. The expression of key thyroid-related genes (n = 9) was monitored by reverse transcription polymerase chain reaction on days 8, 21, and 43 after initiation. As a pilot study, the same markers were studied in a three-dimensional hanging-drop culture system.

RESULTS

In the cultures with 6H or h7H medium, the primary thyroid cells displayed growth in numbers and size. Most cells retained the main morphological characteristics of thyroid cells throughout the first two weeks of culture, and fibroblast-like cells appeared around day 19. By day 21, most thyroid gene markers were retained, but by day 43, several markers were no longer present. The lncRNA transcripts PTCSC2 (spliced) and PTCSC3 were the first to disappear. There were no fundamental differences between the two media in the early period of culture. In the three-dimensional system, most thyroid markers were retained by day 21.

CONCLUSION

Cultures of thyroid cells retain many thyroid characteristics up to day 21. Thereafter, fibroblast-like dedifferentiated cells begin to dominate.

Tissue engineering of the stomach

Tissue engineering combines engineering principles with the biological sciences to create functional replacement tissues. The underlying principle of tissue engineering is that isolated cells combined with biomaterials can form new tissues and organs in vitro and in vivo. This review focuses on stomach tissue engineering, which is a promising approach to the treatment of gastric cancer, the fourth most common malignancy in the world and the second-leading cause of cancer mortality worldwide. Although gastrectomy is a reliable intervention to achieve complete removal of cancer lesions, the limited capacity for food intake after resection results in lower quality of life for patients. To address this issue, we have developed a tissue-engineered stomach to increase the capacity for food intake by creating a new food reservoir. We have transplanted this neo-stomach as a substitute for the original native stomach in a rat model and confirmed functional adaptation. Furthermore, we have demonstrated the feasibility of transplanting a tissue-engineered gastric wall patch in a rat model to alleviate the complications after resection of a large area of the gastric wall. Although progress has been achieved, significant challenges remain to bring this approach to clinical practice. Here, we summarize our work and present the state of the art in stomach tissue engineering.

Contribution of subcutaneous connective tissues to the epithelialization and cyst formation by the skin transplanted subcutaneously

Skins and hollow organs have been shown to form epithelialized cysts when transplanted into subcutaneous tissue of a recipient animal, expanding their surface areas. This system seems to offer a good potential for regenerating organs. We investigated the functional and structural contribution of epithelia and connective tissue compartments in this regeneration system with two experimental systems.

Murine tissue-engineered stomach demonstrates epithelial differentiation

BACKGROUND

Gastric cancer remains the second largest cause of cancer-related mortality worldwide. Postgastrectomy morbidity is considerable and quality of life is poor. Tissue-engineered stomach is a potential replacement solution to restore adequate food reservoir and gastric physiology. In this study, we performed a detailed investigation of the development of tissue-engineered stomach in a mouse model, specifically evaluating epithelial differentiation, proliferation, and the presence of putative stem cell markers.

MATERIALS AND METHODS

Organoid units were isolated from <3 wk-old mouse glandular stomach and seeded onto biodegradable scaffolds. The constructs were implanted into the omentum of adult mice. Implants were harvested at designated time points and analyzed with histology and immunohistochemistry.

RESULTS

Tissue-engineered stomach grows as an expanding sphere with a simple columnar epithelium organized into gastric glands and an adjacent muscularis. The regenerated gastric epithelium demonstrates differentiation of all four cell types: mucous, enteroendocrine, chief, and parietal cells. Tissue-engineered stomach epithelium proliferates at a rate comparable to native glandular stomach and expresses two putative stem cell markers: DCAMKL-1 and Lgr5.

CONCLUSIONS

This study demonstrates the successful generation of tissue-engineered stomach in a mouse model for the first time. Regenerated gastric epithelium is able to appropriately proliferate and differentiate. The generation of murine tissue-engineered stomach is a necessary advance as it provides the transgenic tools required to investigate the molecular and cellular mechanisms of this regenerative process. Delineating the mechanism of how tissue-engineered stomach develops in vivo is an important precursor to its use as a human stomach replacement therapy.

Morphogenesis and cytodifferentiation of the avian retinal pigmented epithelium require downregulation of Group B1 Sox genes

The optic vesicle is a multipotential primordium of the retina, which becomes subdivided into the neural retina and retinal pigmented epithelium domains. Although the roles of several paracrine factors in patterning the optic vesicle have been studied extensively, little is known about cell-autonomous mechanisms that regulate coordinated cell morphogenesis and cytodifferentiation of the retinal pigmented epithelium. Here we demonstrate that members of the SoxB1 gene family, Sox1, Sox2 and Sox3, are all downregulated in the presumptive retinal pigmented epithelium. Constitutive maintenance of SoxB1 expression in the presumptive retinal pigmented epithelium both in vivo and in vitro resulted in the absence of cuboidal morphology and pigmentation, and in concomitant induction of neural differentiation markers. We also demonstrate that exogenous Fgf4 inhibits downregulation all SoxB1 family members in the presumptive retinal pigment epithelium. These results suggest that retinal pigment epithelium morphogenesis and cytodifferentiation requires SoxB1 downregulation, which depends on the absence of exposure to an FGF-like signal.

Molecular analysis of endoderm regionalization

We have engaged in a number of studies in our laboratory that have focused on the molecular mechanisms underlying gut formation, with particular attention being paid to the establishment of regional differences found in the entire gut and within each digestive organ. We have found from our analyses that the presumptive fate of the endoderm in the embryos of vertebrates is determined quite early during development, but the realization of this fate often requires molecular cues from the neighboring tissues such as the lateral plate mesoderm and the mesenchyme derived from it. The mesenchyme seems often to exert instructive or supportive induction effects and, in some cases, a completely inhibitory role during the differentiation of the endodermal epithelium. In addition, many reports on the formation of the stomach, intestine, liver and salivary gland in vertebrates, and of Drosophila gut, all indicate that the morphogenesis and cytodifferentiation of these organs are regulated by the regulated expression of genes encoding growth factors and transcription factors. We have further shown that the epithelium can regulate the differentiation of the mesenchyme into the connective tissue and the smooth muscle layers, thus demonstrating the occurrence of literally interactive processes in the development of the digestive organs.

Histone deacetylases 1 and 2 redundantly regulate cardiac morphogenesis, growth, and contractility

Histone deacetylases (HDACs) tighten chromatin structure and repress gene expression through the removal of acetyl groups from histone tails. The class I HDACs, HDAC1 and HDAC2, are expressed ubiquitously, but their potential roles in tissue-specific gene expression and organogenesis have not been defined. To explore the functions of HDAC1 and HDAC2 in vivo, we generated mice with conditional null alleles of both genes. Whereas global deletion of HDAC1 results in death by embryonic day 9.5, mice lacking HDAC2 survive until the perinatal period, when they succumb to a spectrum of cardiac defects, including obliteration of the lumen of the right ventricle, excessive hyperplasia and apoptosis of cardiomyocytes, and bradycardia. Cardiac-specific deletion of either HDAC1 or HDAC2 does not evoke a phenotype, whereas cardiac-specific deletion of both genes results in neonatal lethality, accompanied by cardiac arrhythmias, dilated cardiomyopathy, and up-regulation of genes encoding skeletal muscle-specific contractile proteins and calcium channels. Our results reveal cell-autonomous and non-cell-autonomous functions for HDAC1 and HDAC2 in the control of myocardial growth, morphogenesis, and contractility, which reflect partially redundant roles of these enzymes in tissue-specific transcriptional repression.

Isolation and identification of mesenchymal stem cells from human lipoma tissue

Lipoma is a benign neoplasm of normal fat cells that appears as a soft, movable swelling, often with a slight yellowish coloration. Human mesenchymal stem cells (MSCs) that have been isolated from bone marrow, blood, and other adult tissues including adipose tissue have the potential to be useful candidates for therapy. No literature had reported about stem cells from lipoma tissue. Here, a new cell culture method is described and utilized to greatly accelerate the growth rate and prolong the lifespan of lipoma-derived MSCs. Cells produced in early cultures display characteristics similar to those previously reported for multipotential stem cells, including a high frequency of anchorage-independent growth in soft agar and a lack of gap junctional intercellular communication in cell types with serpiginous morphology. These cells can differentiate into adipocytes, osteoblasts, and chondrocytes after induction. In conclusion, lipoma-derived stem cells possessing the characteristics of MSCs are described for the first time.

Regeneration of the amphibian intestinal epithelium under the control of stem cell niche

The epithelium of the mammalian digestive tract originates from stem cells and undergoes rapid cell-renewal throughout adulthood. It has been proposed that the microenvironment around the stem cells, called 'niche', plays an important role in epithelial cell-renewal through cell-cell and cell-extracellular matrix interactions. The amphibian intestine, which establishes epithelial cell-renewal during metamorphosis, serves as a unique and good model for studying molecular mechanisms of the stem cell niche. By using the organ culture of the Xenopus laevis intestine, we have previously shown that larval-to-adult epithelial remodeling can be organ-autonomously induced by thyroid hormone (TH) and needs interactions with the surrounding connective tissue. Thus, in this animal model, the functional analysis of TH response genes is useful for clarifying the epithelial-connective tissue interactions essential for intestinal remodeling at the molecular level. Recent progress in culture and transgenic technology now enables us to investigate functions of such TH response genes in the X. laevis intestine and sheds light on molecular aspects of the stem cell niche that are common to the mammalian intestine.

In vitro models of intestinal epithelial cell differentiation

The intestinal epithelium is a particularly interesting tissue as (1) it is in a constant cell renewal from a stem cell pool located in the crypts which form, with the underlying fibroblasts, a stem cell niche and (2) the pluripotent stem cells give rise to four main cell types: enterocytes, mucus, endocrine, and Paneth cells. The mechanisms leading to the determination of phenotype commitment and cell-specific expressions are still poorly understood. Although transgenic mouse models are powerful tools for elucidating the molecular cascades implicated in these processes, cell culture approaches bring easy and elegant ways to study cellular behavior, cell interactions, and cell signaling pathways for example. In the present review, we will describe the major tissue culture technologies that allow differentiation of epithelial cells from undifferentiated embryonic or crypt cells. We will point to the necessity of the re-creation of a complex microenvironment that allows full differentiation process to occur. We will also summarize the characteristics and interesting properties of the cell lines established from human colorectal tumors.

Aging of mesenchymal stem cell in vitro

Background

A hot new topic in medical treatment is the use of mesenchymal stem cells (MSC) in therapy. The low frequency of this subpopulation of stem cells in bone marrow (BM) necessitates their in vitro expansion prior to clinical use. We evaluated the effect of long term culture on the senescence of these cells.

Results

The mean long term culture was 118 days and the mean passage number was 9. The average number of PD decreased from 7.7 to 1.2 in the 10th passage. The mean telomere length decreased from 9.19 Kbp to 8.7 kbp in the 9th passage. Differentiation potential dropped from the 6th passage on. The culture's morphological abnormalities were typical of the Hayflick model of cellular aging.

Conclusion

We believe that MSC enter senescence almost undetectably from the moment of in vitro culturing. Simultaneously these cells are losing their stem cell characteristics. Therefore, it is much better to consider them for cell and gene therapy early on.

Aging of mesenchymal stem cell in vitro

BACKGROUND

A hot new topic in medical treatment is the use of mesenchymal stem cells (MSC) in therapy. The low frequency of this subpopulation of stem cells in bone marrow (BM) necessitates their in vitro expansion prior to clinical use. We evaluated the effect of long term culture on the senescence of these cells.

RESULTS

The mean long term culture was 118 days and the mean passage number was 9. The average number of PD decreased from 7.7 to 1.2 in the 10th passage. The mean telomere length decreased from 9.19 Kbp to 8.7 kbp in the 9th passage. Differentiation potential dropped from the 6th passage on. The culture's morphological abnormalities were typical of the Hayflick model of cellular aging.

CONCLUSION

We believe that MSC enter senescence almost undetectably from the moment of in vitro culturing. Simultaneously these cells are losing their stem cell characteristics. Therefore, it is much better to consider them for cell and gene therapy early on.

Green fluorescent protein gene-transfected peafowl somatic cells participate in the development of chicken embryos

This study was performed to investigate whether the embryonic somatic cells are capable of reconstituting and participating in the embryonic development of chickens to produce chimeras. In order to track the migration behavior of the donor cells, a cell line, originally isolated from an Indian peafowl embryo, was fluorescent-labeled by transfection of the cells with enhanced Green Fluorescent Protein (GFP) and Neomycin resistant (Neo) genes prior to injection into the stage X blastoderm of White Leghorn chickens. The injection was performed with a medium in the presence of 1-5% polyethylene glycol. The development of putative chimeric embryos between the stages three and 24 was examined for GFP expression under fluorescent light. To trace the peafowl cells in the developing chicken embryos, both a species-specific genetic marker originating from the mitochondrial DNA cytochrome b (cyt b) gene and a DNA fragment of GFP gene were used. Of the 185 fertile eggs manipulated, 173 developed into embryos. Fifty-five of them showed positive GFP patches in extra-embryonic tissues, and 15 expressed GFP in intra-embryonic tissues such as those of the head, heart, and gonad. PCR analysis revealed that PCR fragments for the peafowl mitochondrial DNA cyt b and GFP genes were detected in the samples of the GFP positive extra- and intra-embryonic tissues of the chimeras. The present results provide evidence that fluorescent-labeled peafowl embryonic cells carrying GFP and Neo genes are able to participate in the development of chicken embryos to generate chimeras.

Gene transfer into intact fetal skeletal muscle grown in vitro

The development of an organ culture system for growing prenatal intercostal muscle in vitro and its use to study gene function is described. Fetal skeletal muscle is relatively inaccessible during the key stages of its development, and this method enables DNA transfections and other manipulations to be carried out. The system allows cell proliferation and differentiation to continue and also maintains the morphology and fiber types of developing muscle. Gene transfer into cultured embryonic intercostal muscle was achieved by square-pulse electroporation of intact pieces of tissue. Expression of a marker gene (GFP) was found within 5 h and maintained for 2 days in muscle fibers and cells. The technique should enable the function of genes implicated in muscle development and disease to be studied at stages when access is difficult and in a controlled environment.

A tissue-engineered stomach as a replacement of the native stomach

BACKGROUND

Despite recent advances in reconstruction techniques, total gastrectomy is still accompanied by various complications. As an alternative treatment, we propose a tissue-engineered stomach that replaces the mechanical and metabolic functions of a normal stomach. The objective of this study was to demonstrate the function of a tissue-engineered stomach as a replacement of the native stomach.

METHODS

Tissue-engineered stomachs were formed in recipient rats from stomach epithelium organoid units isolated from neonatal donor rats. After 12 weeks, the animals underwent a second operation for replacement of the native stomachs.

RESULTS

Tissue-engineered stomachs were successfully used as a substitute of the native stomach in a rat model. An upper gastrointestinal tract study revealed no evidence of bowel stenosis or obstruction at both anastomosis sites. Histologically, the tissue-engineered stomachs had well-developed vascularized tissue with a neomucosa continuously lining the lumen and stratified smooth muscle layers. Immunohistochemical staining for alpha-actin smooth muscle showed that the smooth muscle layers were arranged in a regular fashion. Scanning electron microscopy showed that the surface topography of the tissue-engineered stomachs resembled that of native stomachs.

CONCLUSIONS

It has been demonstrated that a tissue-engineered stomach can replace a native stomach in a rat model. Replacement of the native stomach by a tissue-engineered stomach had beneficial effects on the formation of neomucosa and smooth muscle layers in the tissue-engineered stomach.

Down-regulation of endodermal Shh is required for gland formation in chicken stomach

During the development of the proventriculus (glandular stomach) of the chicken embryo, the endodermal epithelium invades into the surrounding mesenchyme and forms glands. The glandular epithelial cells produce pepsinogen, while the non-glandular (luminal) epithelial cells secrete mucus. Sonic hedgehog is expressed uniformly in the proventricular epithelium before gland formation, but its expression ceases in gland cells. Here we present evidence that down-regulation of Sonic hedgehog is necessary for gland formation in the epithelium using a specific inhibitor of Sonic hedgehog signaling and virus mediated overexpression of Sonic hedgehog. We also show that gland formation is not induced by down-regulation of Sonic hedgehog alone; a mesenchymal influence is also required.

Adult bone marrow is a rich source of human mesenchymal 'stem' cells but umbilical cord and mobilized adult blood are not

In postnatal life, mesenchymal stem cells (MSC) self-replicate, proliferate and differentiate into mesenchymal tissues, including bone, fat, tendon, muscle and bone marrow (BM) stroma. Possible clinical applications for MSC in stem cell transplantation have been proposed. We have evaluated the frequency, phenotype and differentiation potential of MSC in adult BM, cord blood (CB) and peripheral blood stem cell collections (PBSC). During culture, BM MSC proliferated to confluence in 10-14 d, maintaining a stable non-haemopoietic phenotype, HLA class-1+, CD29+, CD44+, CD90+, CD45-, CD34- and CD14 through subsequent passages. Using the colony forming unit fibroblasts assay, the estimated frequency of MSC in the BM nucleated cell population was 1 in 3.4 x 10(4) cells. Both adipogenic and osteogenic differentiation of BM MSC was demonstrated. In contrast, CB and PBSC mononuclear cells cultured in MSC conditions for two passages produced a population of adherent, non-confluent fibroblast-like cells with a haemopoietic phenotype, CD45+, CD14+, CD34-, CD44-, CD90- and CD29-. In paired experiments, cultured BM MSC and mature BM stroma were seeded with CB cells enriched for CD34+. Similar numbers of colony-forming units of granulocytes-macrophages were produced by MSC-based and standard stroma cultures over 10 weeks. We conclude that adult BM is a reliable source of functional cultured MSC, but CB and PBSC are not.

Kinetics of v-src-induced epithelial-mesenchymal transition in developing glandular stomach

The oncogene function in primary epithelial cells is largely unclear. Recombination organ cultures in combination with the stable and transient gene transfer techniques by retrovirus and electroporation, respectively, enable us to transfer oncogenes specifically into primary epithelial cells of the developing avian glandular stomach (proventriculus). In this system, the epithelium and mesenchyme are mutually dependent on each other for their growth and differentiation. We report here that either stable or transient expression of v-src in the epithelium causes budding and migration of epithelial cells into mesenchyme. In response to the transient expression of v-Src or a constitutive active mutant of MEK, we observed immediate downregulation of the Sonic hedgehog gene and subsequent elimination of E-cadherine expression in migrating cells, suggesting the involvement of MAP kinase signaling pathway in these processes. v-src-expressing cells that were retained in the epithelium underwent apoptosis (anoikis) and detached from the culture. Continuous expression of v-src by, for example, Rous sarcoma virus (RSV) was required for the epithelial cells to acquire the ability to express type I collagen and fibronectin genes (mesenchymal markers), and finally to establish the epithelial-mesenchymal transition. These observations would partly explain why RSV does not apparently cause carcinoma formation, but induces sarcomas exclusively.

In vivo DNA electrotransfer

The use of electrotransfer for DNA delivery to prokaryotic cells, and eukaryotic cells in vitro, has been well known and widely used for many years. However, it is only recently that electric fields have been used to enhance DNA transfer to animal cells in vivo, and this is known as DNA electrotransfer or in vivo DNA electroporation. Some of the advantages of this method of somatic cell gene transfer are that it is a simple method that can be used to transfer almost any DNA construct to animal cells and tissues in vivo; multiple constructs can be co-transfected; it is equally applicable to dividing and nondividing cells; the DNA of interest does not need to be subcloned into a specific viral transfer vector and there is no need for the production of high titre viral stocks; and, as no viral genes are expressed there is less chance of an adverse immunologic reaction to vector sequences. The ease with which efficient in vivo gene transfer can be achieved with in vivo DNA electrotransfer is now allowing genetic analysis to be applied to a number of classic animal model systems where transgenic and embryonic stem cell techniques are not well developed, but for which a wealth of detailed descriptive embryological information is available, or surgical manipulation is much more feasible. As well as exciting applications in developmental biology, in vivo DNA electrotransfer is also being used to transfer genes to skeletal muscle and drive expression of therapeutically active proteins, and to examine exogenous gene and protein function in normal adult cells situated within the complex environment of a tissue and organ system in vivo. Thus, in effect providing the in vivo equivalent of the in vitro transient transfection assay. As the widespread use of in vivo electroporation has really only just begun, it is likely that the future will hold many more applications for this technology in basic research, biotechnology and clinical research areas.

Application of collagen sponge scaffold to muscular defects of the esophagus: an experimental study in piglets

BACKGROUND/PURPOSE

Circular myotomy often has been used to elongate the esophagus in end-to-end anastomosis for esophageal atresia with a long gap. Defects of the muscular layer often have led to the ballooning of the esophagus during the postoperative course. Recently, successful regeneration of the neo-esophagus using collagen sponge scaffold (CSS) for self-tissue regeneration has been reported. The authors applied this CSS to the muscular defect after circular myotomy in animal experiments.

METHODS

Myectomy or myotomy of the cervical or thoracic esophagus was performed in 11 piglets. CSS was applied to the amuscular site, which was 20 to 30 mm in length, to examine the regeneration of the muscular layer in 8 piglets (CSS group). The amuscular site was not wrapped by CSS in 3 piglets as a control (control group). Two months after operation, the animals were killed, and their operated esophagi were examined macroscopically and microscopically.

RESULTS

All 11 piglets increased in weight normally without any sign of dysphagia or vomiting. The amuscular site onto which CSS was implanted was covered with loose connective tissue, but muscle regeneration was not found microscopically. The amuscular site, which had been wrapped by CSS, was not distended in any of the 8 piglets when inflated, and ballooning was observed in all 3 of the control group.

CONCLUSION

The results suggested that application of CSS to the site of circular myotomy for esophageal atresia with a long gap might not induce muscle regeneration but could prevent postoperative ballooning by inducing connective tissue growth.

Sparking new frontiers: using in vivo electroporation for genetic manipulations

In vivo electroporation is a fascinating new approach by which gene expression, regulation, and function can be studied in developmental systems. This technique offers new opportunities for manipulations in animal models that lack genetic approaches, including avians. Furthermore, this approach is applicable to other embryo populations including mice, ascidians, zebrafish, Xenopus, and Drosophila. In this review, we discuss technical aspects of in vivo electroporation, review recent studies where this approach has been utilized successfully, and identify future directions.

Gene transfer into chicken embryos as an effective system of analysis in developmental biology

Chicken embryos have been used as a model animal in developmental biology since the time of comparative and experimental embryology. Recent application of gene transfer techniques to the chicken embryo increases their value as an experimental animal. Today, gene transfer into chicken cells is performed by three major systems, lipofection, electroporation and the virus-mediated method. Each system has its own features and applicability. In this overview and the associated four minireviews, the methods and application of each system will be presented.

Applications of microelectroporation for studies of chick embryogenesis

A technique by which genes can be introduced into the cells and tissues of developing embryos has great potential for studying the roles of genes during vertebrate embryogenesis. The 'microelectroporation' technique, in which DNA is introduced into cells within a restricted area of developing chick embryos with high reproducibility, was developed by the authors. In this review, the advantages and applications of this microelectroporation technique for developmental studies and functional analysis of genes in chick embryos is discussed.