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Shulamit Levenberg

Publications and source records attributed to Shulamit Levenberg.

10 recordsLinked to original sources
PubMed2007

Tissue engineering of vascularized cardiac muscle from human embryonic stem cells.

Transplantation of a tissue-engineered heart muscle represents a novel experimental therapeutic paradigm for myocardial diseases. However, this strategy has been hampered by the lack of sources for human cardiomyocytes and by the scarce vasculature in the ischemic area limiting the engraftment and survival of the transplanted muscle. Beyond the necessity of endothelial capillaries for the delivery of oxygen and nutrients to the grafted muscle tissue, interactions between endothelial and cardiomyocyte cells may also play a key role in promoting cell survival and proliferation. In the present study, we describe the formation of synchronously contracting engineered human cardiac tissue derived from human embryonic stem cells containing endothelial vessel networks. The 3D muscle consisted of cardiomyocytes, endothelial cells (ECs), and embryonic fibroblasts (EmFs). The formed vessels were further stabilized by the presence of mural cells originating from the EmFs. The presence of EmFs decreased EC death and increased EC proliferation. Moreover, the presence of endothelial capillaries augmented cardiomyocyte proliferation and did not hamper cardiomyocyte orientation and alignment. Immunostaining, ultrastructural analysis (using transmission electron microscopy), RT-PCR, pharmacological, and confocal laser calcium imaging studies demonstrated the presence of cardiac-specific molecular, ultrastructural, and functional properties of the generated tissue constructs with synchronous activity mediated by action potential propagation through gap junctions. In summary, this is the first report of the construction of 3D vascularized human cardiac tissue that may have unique applications for studies of cardiac development, function, and tissue replacement therapy.

Cell Culture Techniques↗
PubMed2006

Engineering three-dimensional tissue structures using stem cells.

The worldwide status of rapidly increasing demand for organ and tissue transplantation has promoted tissue engineering as a promising alternative, in particular the use of stem cells. Human embryonic stem cells (hESCs) have the advantage of differentiating to all cell types in the body and high proliferation capabilities. Considering their ability to organize into complex multi-cell-type structures during embryonic-like differentiation, hESCs can potentially provide a source of cells for tissue engineering applications and meet the growing demand for viable human tissue structures in therapeutic clinical application. This chapter describes first steps toward realizing this goal gathered from our experience in growing and differentiating hESCs in three dimensions.

Cell Differentiation↗
PubMed2005

Engineering vascularized skeletal muscle tissue.

One of the major obstacles in engineering thick, complex tissues such as muscle is the need to vascularize the tissue in vitro. Vascularization in vitro could maintain cell viability during tissue growth, induce structural organization and promote vascularization upon implantation. Here we describe the induction of endothelial vessel networks in engineered skeletal muscle tissue constructs using a three-dimensional multiculture system consisting of myoblasts, embryonic fibroblasts and endothelial cells coseeded on highly porous, biodegradable polymer scaffolds. Analysis of the conditions for induction and stabilization of the vessels in vitro showed that addition of embryonic fibroblasts increased the levels of vascular endothelial growth factor expression in the construct and promoted formation and stabilization of the endothelial vessels. We studied the survival and vascularization of the engineered muscle implants in vivo in three different models. Prevascularization improved the vascularization, blood perfusion and survival of the muscle tissue constructs after transplantation.

Animals↗
PubMed2005

Engineering blood vessels from stem cells: recent advances and applications.

Endothelial cells organized into blood vessels are critical for the formation and maintenance of most tissues in the body and are involved in regulating physiological processes such as angiogenesis, inflammation and thrombosis. Endothelial cells are of great research interest, because of their potential to treat vascular diseases and to stimulate the growth of ischaemic tissue. They can be used to engineer artificial vessels, repair damaged vessels, and to induce the formation of vessel networks in engineered tissues. For such clinical applications, proliferating human endothelial progenitor cells can be isolated from adult tissues or embryonic stem cells. Recently, these cells were successfully used to engineer single vessels and to stimulate capillary networks, both in vitro and in vivo.

Animals↗
PubMed2004

Nanoliter-scale synthesis of arrayed biomaterials and application to human embryonic stem cells.

Identification of biomaterials that support appropriate cellular attachment, proliferation and gene expression patterns is critical for tissue engineering and cell therapy. Here we describe an approach for rapid, nanoliter-scale synthesis of biomaterials and characterization of their interactions with cells. We simultaneously characterize over 1,700 human embryonic stem cell-material interactions and identify a host of unexpected materials effects that offer new levels of control over human embryonic stem cell behavior.

Biocompatible Materials↗
PubMed2004

Layer-by-layer deposition of hyaluronic acid and poly-L-lysine for patterned cell co-cultures.

A novel method for patterning cellular co-cultures that uses the layer-by-layer deposition of ionic biopolymers is described. Non-biofouling hyaluronic acid (HA) micropatterns were used to immobilize cells and proteins to glass substrates. Subsequent ionic adsorption of poly-L-lysine (PLL) to HA patterns was used to switch the HA surfaces from cell repulsive to adherent thereby facilitating the adhesion of a second cell type. The utility of this approach to pattern co-cultures of hepatocytes or embryonic stem cells with fibroblasts was demonstrated. In addition, the versatility of this approach to generate patterned co-cultures irrespective of the primary cell seeding and relative adhesion of the seeded cells was demonstrated. Thus, the proposed method may be a useful tool for fabricating controlled cellular co-cultures for cell-cell interaction studies and tissue engineering applications.

Adsorption↗
PubMed2003

Differentiation of human embryonic stem cells on three-dimensional polymer scaffolds.

Human embryonic stem (hES) cells hold promise as an unlimited source of cells for transplantation therapies. However, control of their proliferation and differentiation into complex, viable 3D tissues is challenging. Here we examine the use of biodegradable polymer scaffolds for promoting hES cell growth and differentiation and formation of 3D structures. We show that complex structures with features of various committed embryonic tissues can be generated, in vitro, by using early differentiating hES cells and further inducing their differentiation in a supportive 3D environment such as poly(lactic-co-glycolic acid)/poly(L-lactic acid) polymer scaffolds. We found that hES cell differentiation and organization can be influenced by the scaffold and directed by growth factors such as retinoic acid, transforming growth factor beta, activin-A, or insulin-like growth factor. These growth factors induced differentiation into 3D structures with characteristics of developing neural tissues, cartilage, or liver, respectively. In addition, formation of a 3D vessel-like network was observed. When transplanted into severe combined immunodeficient mice, the constructs continue to express specific human proteins in defined differentiated structures and appear to recruit and anastamose with the host vasculature. This approach provides a unique culture system for addressing questions in cell and developmental biology, and provides a potential mechanism for creating viable human tissue structures for therapeutic applications.

Animals↗
PubMed2002

Endothelial cells derived from human embryonic stem cells.

Human embryonic stem cells have the potential to differentiate into various cell types and, thus, may be useful as a source of cells for transplantation or tissue engineering. We describe here the differentiation steps of human embryonic stem cells into endothelial cells forming vascular-like structures. The human embryonic-derived endothelial cells were isolated by using platelet endothelial cell-adhesion molecule-1 (PECAM1) antibodies, their behavior was characterized in vitro and in vivo, and their potential in tissue engineering was examined. We show that the isolated embryonic PECAM1+ cells, grown in culture, display characteristics similar to vessel endothelium. The cells express endothelial cell markers in a pattern similar to human umbilical vein endothelial cells, their junctions are correctly organized, and they have high metabolism of acetylated low-density lipoprotein. In addition, the cells are able to differentiate and form tube-like structures when cultured on matrigel. In vivo, when transplanted into SCID mice, the cells appeared to form microvessels containing mouse blood cells. With further studies, these cells could provide a source of human endothelial cells that could be beneficial for potential applications such as engineering new blood vessels, endothelial cell transplantation into the heart for myocardial regeneration, and induction of angiogenesis for treatment of regional ischemia.

Cell Differentiation↗
PubMedDate not supplied

Neurotrophin-induced differentiation of human embryonic stem cells on three-dimensional polymeric scaffolds.

Human embryonic stem (hES) cells have the potential to form various cell types, including neural cells for the treatment of diseases such as Parkinson's, spinal cord injury, and glaucoma. Here, we have investigated the neuronal differentiation of hES cells on three-dimensional scaffolds fabricated from degradable poly(alpha-hydroxy esters) including poly(lactic-co-glycolic acid) and poly(L-lactic acid). When cultured in vitro, neural rosette-like structures developed throughout the scaffolds with differentiation dependent on factors in the medium (e.g., retinoic acid [RA], nerve growth factor [NGF], and neurotrophin 3 [NT-3]) and the differentiation stage of the cells. Specifically, enhanced numbers of neural structures and staining of nestin (a marker of neural precursors) and beta(III)-tubulin (indicative of neural differentiation) were observed with hES cell-seeded polymer scaffolds when cultured with both NGF and NT-3 when compared with control medium. In addition, vascular structures were found throughout the engineered tissues when cultured with the neurotrophins, but not in the presence of RA.

Cell Culture Techniques↗