ANANDHU THAMPI3RD SEMESTER PHYSICS

CUSAT

What are Stem cells?

Stem cells are called “master cells” Stem cells are undifferentiated biological cells that can differentiate into

specialized cells and can divide  to produce more stem cells Stem cells give rise to brain cells, nerve cells, heart cells, pancreatic cells, etc.  In mammals, there are two types of stem cells: embryonic stem cells, which

are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues

STEM CELLS - PROPERTIES

Self-renewal: the ability to go through numerous cycles of cell division while maintaining the undifferentiated state.

Self-renewal property is to maintain and repair the tissue. Thus they have potential to replace cell tissue damaged by severe illnesses.

Potency: the capacity to differentiate into specialized cell types Two mechanisms exist to ensure that a stem cell population is maintained

1) Obligatory asymmetric replication: a stem cell divides into one mother cell that is identical to the original stem cell, and another daughter cell that is differentiated

2) Stochastic differentiation:when one stem cell develops into two differentiated daughter cells, another stem cell undergoes mitosis and produces two stem cells identical to the original.

Potency definitions of stem cells

Totipotent : stem cells can differentiate into embryonic and extraembryonic cell types. It can differentiate into an entire organism , result from fusion of egg and sperm.

Pluripotent stem cells are the descendants of totipotent cells and can differentiate into nearly all cells

Multipotent stem cells can differentiate into a number of cell types, but only those of a closely related family of cells

Oligopotent stem cells can differentiate into only a few cell types, such as lymphoid or myeloid stem cells

Unipotent cells can produce only one cell type, their own, but have the property of self-renewal, which distinguishes them from non-stem cells

Types of stem cells

A. Embryonic : derived from the inner cell mass of a blastocyst / human embryo

Sources

1. Excess fertilized eggs from IVF (in-vitro fertilization) clinics

2. Therapeutic cloning (somatic cell nuclear transfer)

 Human embryos reach the blastocyst stage 4–5 days post fertilization, at which time they consist of 50–150 cells

 

Adult : derived from mature organisms that can divide to form more differentiated cells .but are less versatile and more difficult to identify, isolate, and purify.

Eg.: Stem cells have been found in the blood, bone marrow, liver, kidney, cornea, dental pulp, brain, skin, muscle

Most adult stem cells are multipotent

Fetal : derived from aborted fetal tissue

Umbilical : derived from umbilical cords

- All blood cell types (red blood cells, white blood cells, and platelets)

Stem-cell therapy

Stem-cell therapy is the use of stem cells to treat or prevent a disease or condition.

Bone marrow transplant is the most widely used stem-cell therapy, but some therapies derived from umbilical cord blood are also in use

It is also known as regenerative medicine, promotes the reparative response of diseased, dysfunctional or injured tissue using stem cells or their derivatives

Research is underway to develop  stem-cell treatments for neurodegenerative diseases and conditions such as diabetes, heart disease, and other conditions

How stem cell therapy works?

When stem cells are transplanted into the

body and arrive into the injured part,

Brain being targeted for tissue

regeneration,

The stem cells are coming in contact with

growth chemical’s (like EGF’s , NGF’s and

HGF’s )in the body.

These chemicals program the stem cells to

differentiate into the tissue surrounding it.

Disease cured by stem cell therapy

Spinal cord injuries Diabetes mellitus Cancer Stroke Tooth implanting Deafness and blindness Baldness Alzheimer's disease Parkinson's disease Heart diseases

Ethical issues

As human embryonic stem cell are isolated from few days old blastocyst as well as fetal tissues

Many prolifers believe that human life becomes a human person at the time of fertilization

Others disagree : they believe that an embryo has potential to develop into a person, but is not a person itself.

researchers have moved on to more ethical study methods, such as Induced Pluripotent Stem Cells (iPS). iPS is artificially derived from a non-pluripotent cell, such as adult somatic cells

Nowadays stem cell treatment has been spreaded throughout the world. It has also been grown commercially in developed countries

Advantage The critical shortage of organs

available for transplantation may be solved in the future by auto-graft techniques

Security : low toxicity or non toxic

Obstacles Difficulty of performing

transplantation and caring for post-transplantation patients.

Specific factors that aid or hinder acceptance of the particular transplant

Ability to obtain source material due to ethical concerns

CONCLUSION

It is thought that one day it may be the major key to treat various diseases

Stem cells gives a huge promise for regenerative medicine

Ethical concerns need to be taken into account

Stem cell therapy have no side effects

Organ transplantation becomes easier

references

Bruno Christ, Jana Oerlecke, Peggy Stock, “Animal Models for Stem Cell Therapy” , Humana Press 2014

Nicole I.Nieden, “Embryonic Stem Cell Therapy for Osteo-Degenerative Diseases: Methods and Protocols” , Humana Press

2011

T. Sun, “Neural Stem Cells and Therapy” , Intech 2012

www.Wikipedia.org

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