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Epithelial–Mesenchymal Transition

Origin of Epithelium and Mesenchyme

• There are two major types of cell arrangements in the embryo:

• epithelial cells, which are tightly connected to one another in sheets or tubes,

• and mesenchymal cells, which are unconnected to one other and operate as independent units.

Origin of Epithelium and Mesenchyme

• Epithelia are sheets or tubes of connected cells; they can originate from any germ layer.

• Meschymal cells are loosely packed unconnected cells; mesenchyme contains collagen bundles and fibroblasts; they are derived from the mesoderm or neural crest.

In the Adult

• Epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body.

• Epithelium is classified as a primary body tissue, the other ones being connective tissue, muscle tissue and nervous tissue.

In the Adult

• Mesenchyme later differentiates into blood vessels, blood-related organs, and connective tissues.

• All organs consist of an epithelium and an associated mesenchyme.

Epithelial–Mesenchymal Transition

Hartmut Beug

Actin/

DAPI

E-cadherin

Vimentin

Desmosomes

Vimentin

Epithelial

Mesenchymal

Epithelial–Mesenchymal TransitionJean Paul Thiery

EMT in Tissue RemodellingJean Paul Thiery

The generation of three germ layers

下胚层

The migration of neural crest

Somitogenesis

The generation of glomerulus

EMT During Tumor ProgressionHartmut Beug

Paper One

Epithelial-to Mesenchymal Transition Generates Proliferative Human Islet Prec

ursor Cells

• Marvin Gershengorn, Anandwardhan Hardikar, Chiju Wei, Elizabeth Geras-Raaka, Bernice Marcus- Samuels, Bruce M. Raaka• SCIENCE VOL 306, 2004

Embryonic StemEmbryonic StemCellCell

Bone MarrowBone MarrowStem CellStem Cell

TransdifferentiationTransdifferentiation

Pancreatic stem Pancreatic stem cellcell

Cadaveric hCadaveric human isletsuman islets

Potential Sources of Islet Precursor CellsPotential Sources of Islet Precursor Cells

hIPC Generation and ICA Formation hIPC Generation and ICA Formation

A B C

1 hr 24 hr 6 day

D E F

Transition From Insulin+ to VimentiTransition From Insulin+ to Vimentin+ Cells n+ Cells

Redifferentiation From Vimentin+ to Redifferentiation From Vimentin+ to Insulin+ Cells Insulin+ Cells

Islet Precursors Generated by EMT Islet Precursors Generated by EMT Marvin Gershengorn

EMT in Progenitor Cells of The Developing Endocrine Pancreas

Joel F. Habener

EpitheliumEpithelium

Basel membraneBasel membrane

ECMECM

Acinar cellAcinar cell

Islet

Paper Two

Islet-Derived Fibroblast-Like Cells Are Not Derived via Epithelial-Mesenchymal Transition From Pdx-1 or Insulin-Positive

Cells

• Lucas G. Chase, Fernando Ulloa-Montoya, Benjamin L. Kidder, and Catherine M. Verfaillie• Diabetes 56:3–7, 2007

Lineage Tracing on Proliferative Fibroblast-like Cell Populations

Fibroblast-like Cells Are Not Generated From Insulin+/PDX1+ Cells

About 25% of All Insulin-Expressing Cells Coexpressed EGFP

Nadya L. Lumelsky

Paper Three

In Vitro Proliferation of Cells Derived From Adult Human -Cells Revealed By Cell-

Lineage Tracing

• Holger A. Russ, Yael Bar, Philippe Ravassard, and Shimon Efrat• Diabetes 57, 2008

In Vitro Lineage Tracing of Islet Beta Cells

Labeling of human islet cells with the two-virus system