Introduction to Stem Cells1

INTRODUCTION OF STEM CELL TECHNOLOGY

Dr. Hariom Yadav

Stem Cell DefinitionA cell that has the ability to continuously divide and differentiate (develop) into various other kind(s) of cells/tissues

Stem Cell CharacteristicsBlank cells (unspecialized)Capable of dividing and renewing themselves for long periods of time (proliferation and renewal)Have the potential to give rise to specialized cell types (differentiation)

Kinds of Stem Cells

Stem cell typeDescriptionExamplesTotipotentEach cell can develop into a new individualCells from early (1-3 days) embryosPluripotentCells can form any (over 200) cell typesSome cells of blastocyst (5 to 14 days)MultipotentCells differentiated, but can form a number of other tissuesFetal tissue, cord blood, and adult stem cells

Dr. Hariom YadavStem Cell DifferentiationPrinceton University

Dr. Hariom Yadav

Kinds of Stem Cells

Embryonic stem cells come from a five to six-day-old embryo. They have the ability to form virtually any type of cell found in the human body.

Embryonic germ cells are derived from the part of a human embryo or foetus that will ultimately produce eggs or sperm (gametes).

Adult stem cells are undifferentiated cells found among specialised or differentiated cells in a tissue or organ after birth. Based on current research they appear to have a more restricted ability to produce different cell types and to self-renew.

Blastocyst DiagramPrinceton University

Derivation and Use of Embryonic Stem Cell LinesHeartrepaired

*Dr. Hariom Yadav

Dr. Hariom Yadav

Dr. Hariom Yadav

Dr. Hariom Yadav

*Dr. Hariom YadavAdult stem cells

Dr. Hariom Yadav

Dr. Hariom Yadav

Dr. Hariom Yadav

Deterministic model of hematopoiesis

ApplicationsDiseaseDiabetes, Spinal cord injury, Parkinsons disease, heart diseaseGenetic based DiseaseCystic fibrosis, Huntingtons

*Dr. Hariom Yadav

Dr. Hariom Yadav

*Dr. Hariom Yadav

Dr. Hariom Yadav

*Dr. Hariom Yadav

Dr. Hariom Yadav

*Dr. Hariom Yadav

Dr. Hariom Yadav

*Dr. Hariom Yadav

Dr. Hariom Yadav

*Dr. Hariom Yadav

Dr. Hariom Yadav

*Dr. Hariom Yadav

Dr. Hariom Yadav

*Stem cells are different from other cells of the body in that they have the ability to differentiate into other cell/tissue types. This ability allows them to replace cells that have died. With this ability, they have been used to replace defective cells/tissues in patients who have certain diseases or defects.*Common variants, called polymorphisms, occur at greater than 1% frequency

I have given some examples of how exposure induced risk is modified in various ways

Typically the effects are modest in magnitude.

We are interested in how genetics modifies Exposure and exposure-related diseases Because..

*Stem cells can be classified into three broad categories, based on their ability to differentiate. Totipotent stem cells are found only in early embryos. Each cell can form a complete organism (e.g., identical twins). Pluripotent stem cells exist in the undifferentiated inner cell mass of the blastocyst and can form any of the over 200 different cell types found in the body. Multipotent stem cells are derived from fetal tissue, cord blood and adult stem cells. Although their ability to differentiate is more limited than pluripotent stem cells, they already have a track record of success in cell-based therapies. Here is a current list of the sources of stem cells:Embryonic stem cells - are harvested from the inner cell mass of the blastocyst seven to ten days after fertilization.Fetal stem cells - are taken from the germline tissues that will make up the gonads of aborted fetuses.Umbilical cord stem cells - Umbilical cord blood contains stem cells similar to those found in bone marrow.Placenta derived stem cells - up to ten times as many stem cells can be harvested from a placenta as from cord blood.Adult stem cells - Many adult tissues contain stem cells that can be isolated.*The inner cell mass (the part that would form the fetus) of the embryo is isolated and disrupted to form embryonic cell lines. This process destroys the embryo. Under special culture conditions, the cells of the embryonic lines can be coaxed to form certain kinds of differentiated cell types. In theory, these differentiated cells could be used to repair or replace defective cells or tissues.