Biomedical subjects

Anna Ziskind

Publications and source records attributed to Anna Ziskind.

7 recordsLinked to original sources

PubMed2006

Vascular cells.

Embryonic stem (ES) cells are cells derived from the inner cell mass of a blastocyst stage embryo. These self-renewing multipotent cells are able to differentiate to the three embryonic germ layers, the endoderm, ectoderm, and mesoderm, and are thus able to produce virtually all cell types. The ES cell capacity to generate various cell types has been studied extensively, and exploitation of ES cell characteristics allowed the production of several differentiated cell types of multiple tissues. Moreover, the process of ES cell differentiation provides a unique opportunity to observe early embryonic developmental events that are unattainable in the embryo itself. This chapter addresses the in vitro differentiation procedure of endothelial and vascular smooth muscle cells from human ES cells, with reference to similar studies performed in mouse and nonhuman primate ES cells, and provides several tools for the detailed characterization of differentiated cells.

Animals↗

PubMed2006

Human embryonic stem cells for vascular development and repair.

Embryonic stem cells, derived from the inner cell mass of embryos in the blastocyst stage, are cells capable of perpetual self-renewal and long-term propagation and hold the potential to differentiate to progeny of the three embryonic germ layers. Since their derivation approximately two decades ago, exploration of mouse ES cells made major advances in ES cell differentiation research and in the successful development and propagation of various cell types. The subsequent derivation of ES cells from human embryos allows detailed study of early developmental events practically unreachable in early human embryos, and the potential derivation of a variety of adult cell types differentiated from the ES cells holds immense therapeutic promise. Recently, the study of ES cell-derived teratomas identified the partial presence of human ES cell-derived premature vessels within the teratoma, and a preliminary protocol for the in vitro derivation of a vascular progenitor was developed based on the study with the mouse ES cells. Furthermore, genetic profiling identified a pattern of expression of various endothelial and vascular smooth muscle cell genes that provide additional information on the degree of vascular development that ES cells undergo. Finally, the clinical application of ES cells in transplantation medicine is closer than ever following the affirmation that human ES cell-derived endothelial progenitors conferred increased neovascularization in transplanted engineered skeletal muscle. This review summarizes these recent advances in vascular development from human ES cells and their potential clinical applications.

Animals↗

PubMed2005

Molecular analysis of cardiomyocytes derived from human embryonic stem cells.

During early embryogenesis, the cardiovascular system is the first system to be established and is initiated by a process involving the hypoblastic cells of the primitive endoderm. Human embryonic stem (hES) cells provide a model to investigate the early developmental stages of this system. When removed from their feeder layer, hESC create embryoid bodies (EB) which, when plated, develop areas of beating cells in 21.5% of the EB. These spontaneously contracting cells were demonstrated using histology, immunostaining and reverse transcription-polymerase chain reaction (RT-PCR), to possess morphological and molecular characteristics consistent with cardiomyocytic phenotypes. In addition, the expression pattern of specific cardiomyocytic genes in human EB (hEB) was demonstrated and analyzed for the first time. GATA-4 is the first gene to be expressed in 6-day-old EB. Alpha cardiac actin and atrial natriuretic factor are expressed in older hEB at 10 and 20 days, respectively. Light chain ventricular myosin (MLC-2V) was expressed only in EB with beating areas and its expression increased with time. Alpha heavy chain myosin (alpha-MHC) expression declined in the pulsating hEB with time, in contrast to events in EB derived from mice. We conclude that human embryonic stem cells can provide a useful tool for research on embryogenesis in general and cardiovascular development in particular.

Biomarkers↗

PubMed2004

Three-dimensional porous alginate scaffolds provide a conducive environment for generation of well-vascularized embryoid bodies from human embryonic stem cells.

Differentiation of human embryonic stem cells (hESCs) can be instigated through the formation of embryo-like aggregates in suspension, termed human embryoid bodies (hEBs). Controlling cell aggregation and agglomeration during hEBs formation has a profound effect on the extent of cell proliferation and differentiation. In a previous work, we showed that control over hEBs formation and differentiation can be achieved via cultivation of hESC suspensions in a rotating bioreactor system. We now report that hEBs can be generated directly from hESC suspensions within three-dimensional (3D) porous alginate scaffolds. The confining environments of the alginate scaffold pores enabled efficient formation of hEBs with a relatively high degree of cell proliferation and differentiation; encouraged round, small-sized hEBs; and induced vasculogenesis in the forming hEBs to a greater extent than in static or rotating cultures. We therefore conclude that differentiation of hEBs can be induced and directed by physical constraints in addition to chemical cues.

Alginates↗

PubMed2004

Vascular development in early human embryos and in teratomas derived from human embryonic stem cells.

During early human embryonic development, blood vessels are stimulated to grow, branch, and invade developing tissues and organs. Pluripotent human embryonic stem cells (hESCs) are endowed with the capacity to differentiate into cells of blood and lymphatic vessels. The present study aimed to follow vasculogenesis during the early stages of developing human vasculature and to examine whether human neovasculogenesis within teratomas generated in SCID mice from hESCs follows a similar course and can be used as a model for the development of human vasculature. Markers and gene profiling of smooth muscle cells and endothelial cells of blood and lymphatic vessels were used to follow neovasculogenesis and lymphangiogenesis in early developing human embryos (4-8 weeks) and in teratomas generated from hESCs. The involvement of vascular smooth muscle cells in the early stages of developing human embryonic blood vessels is demonstrated, as well as the remodeling kinetics of the developing human embryonic blood and lymphatic vasculature. In teratomas, human vascular cells were demonstrated to be associated with developing blood vessels. Processes of intensive remodeling of blood vessels during the early stages of human development are indicated by the upregulation of angiogenic factors and specific structural proteins. At the same time, evidence for lymphatic sprouting and moderate activation of lymphangiogenesis is demonstrated during these developmental stages. In the teratomas induced by hESCs, human angiogenesis and lymphangiogenesis are relatively insignificant. The main source of blood vessels developing within the teratomas is provided by the murine host. We conclude that the teratoma model has only limited value as a model to study human neovasculogenesis and that other in vitro methods for spontaneous and guided differentiation of hESCs may prove more useful.

Animals↗

PubMed2004

Differentiation of human embryonic stem cells into insulin-producing clusters.

Type I diabetes mellitus is caused by an autoimmune destruction of the insulin-producing beta cells. The major obstacle in using transplantation for curing the disease is the limited source of insulin-producing cells. The isolation of human embryonic stem (hES) cells introduced a new prospect for obtaining a sufficient number of beta cells for transplantation. We present here a method for forming immature islet-like clusters of insulin-producing cells derived from hES cells. The protocol consisted of several steps. Embryoid bodies were first cultured and plated in insulin-transferrin-selenium-fibronectin medium, followed by medium supplemented with N2, B27, and basic fibroblast growth factor (bFGF). Next, the glucose concentration in the medium was lowered, bFGF was withdrawn, and nicotinamide was added. Dissociating the cells and growing them in suspension resulted in the formation of clusters which exhibited higher insulin secretion and had longer durability than cells grown as monolayers. Reverse transcription-polymerase chain reaction detected an enhanced expression of pancreatic genes in the differentiated cells. Immunofluorescence and in situ hybridization analyses revealed a high percentage of insulin-expressing cells in the clusters. In addition to insulin, most cells also coexpressed glucagon or somatostatin, indicating a similarity to immature pancreatic cells. Further improvement of this insulin-producing cell protocol may lead to the formation of an unlimited source of cells suitable for transplantation.

Apoptosis↗

PubMed2003

Human embryonic stem cells as an in vitro model for human vascular development and the induction of vascular differentiation.

Early embryonic blood vessels are typically composed of fragile tubes of endothelial cells encircled by vascular smooth muscle cells. Early human vasculogenesis was explored in spontaneous and directed differentiation models derived from human embryonic stem (HES) cells. In a 3-dimensional (3D) model, HES cells were studied for their potential for vascular differentiation during the spontaneous formation of embryoid bodies. Directed differentiation was investigated by means of a 2-dimensional (2D) differentiation method to promote vascular differentiation from HES cells (without the formation of embryoid bodies). Using this latter approach, up-regulation of early lineage markers of endothelial progenitors were induced. Additional culture under strict conditions and exposure to angiogenic growth factors resulted in a prolonged differentiation pathway into mature endothelial cells and up-regulation of vascular smooth muscle cell markers. The use of 3D collagen gels and Matrigel assays for the induction and inhibition of human vascular sprouting in vitro further established the vascular potential of the cells generated by the 2D differentiation system. Our study shows that HES cells can provide useful models to study early differentiation and development of blood vessels. Moreover, the 2D differentiation model facilitates both the production of vascular lineage cells from HES cells for various potential therapeutic applications and also provides a model for studying the mechanisms involved in early human embryonic blood vessel development.

Becaplermin↗