The diversity of cellular life

Colonies of primitive unicellular organisms don’t show emergent

properties Prokaryotic organisms or

primitive eukaryotic organisms (algae, protistae) exist in colonies of identical cells

While the cells co-operate, they do not fuse to form a single mass and so don’t form a single organism

Each cell has identical structure and function

Multicellular organisms have differentiated cells

Cells are specialised: Blood cells Muscle cells Retinal cells Glandular cells Epithelial cells

Each cell type has a special task and structure

Each cell has the same DNA, but only a section of it is expressed

Levels of ‘organisation’ in a multicellular organism

1.CELL

2.TISSUE

3.ORGANS

4.ORGAN SYSTEMS

Cardiac myocytes

Heart

Cardiovascular system

4 key animal tissue types

1.Epithelial

2.Connective

3.Muscle

4.Nervous

Human Anatomy, Larry M. Frolich, Ph.D.

Human Anatomy, Larry M. Frolich, Ph.D.

Simple: just one layer or cell shape

Stratified: multiple layers and cell shapes

Classes of Epithelia

“ciliated” literally = eyelashes(see next page)

Stratified: regenerate from below

CONNECTIVE TISSUES

“Areolar tissue” as model

Universal in body

Underlies epithelium, supports capillaries, small nerves

Cells of Connective TissuesFibroblasts make fibres – cartilage, ligaments,

blood, bone

Immune cells in areolar tissue

Human Anatomy, Larry M. Frolich, Ph.D.

Different types of Connective tissues

Dense

Ligaments

CartilageBone

Loose

Fat

Areolar

Tissue types3. Muscle tissueSkeletalCardiacSmooth

Tissue types3. Nervous tissueSkeletalCardiacSmooth

Neuroglia

Cell Differentiation Harvard Animation

What are stem cells?Cells that are able to generate more specialised

types of cell types through the process of cell differentiation

Cells that can divide to make identical copies of themselves, through self-renewal

You can learn all about stem cells by watching the beautiful animation from Utah Genetics here:

Stem Cells

Different types of stem cells

1. Embryonic Stem Cells

Here, you can learn how embryonic stem cells are made:

Quck guide to Embryonic stem cells

Here is the BBC video on how embryonic stem cells are made:

How to make stem cells

Different types of stem cells

2. Somatic Stem Cells

(also called adult stem cells)

Exist naturally in the body

Used for bone marrow transplants

Can only differentiate into dedicated cell types

Adult Stem Cells are committed to become one

type of cell

Stem cells in the adult brain:Are they still working for us now?

Stem cells in mature skeletal muscle:Is there power still in our stem cells?

Different types of stem cells

3. Induced pluripotential Stem Cells

Created artificially in the lab by ‘reprogramming’ a patients own cells

Made from patient’s own cells – fat, skin, fibroblasts

Can become any cell in the body (even a whole mouse!)

Induced pluripotential Stem Cells – The future!

Learn the story of iPS stem cells from Utah Genetics…

IPS stem cells

Pros and Cons to iPS cell technology

Pros:Cells would be genetically identical to patient or donor of skin

cells (no immune rejection!)Do not need to use an embryo

Cons:Cells would still have genetic defectsOne of the pluripotency genes is a cancer geneViruses might insert genes in places we don’t want them

(causing mutations)

Different types of stem cells

4. Therapeutic Cloning: ‘patient-specific embryonic stem cells’

Can theoretically create pluripotent stem cells from patient’s own cells

Ethically highly controversial

Scientists have not yet grown a cloned human to the blastocyst stage

Different types of stem cells

Stem Cells used in medicine: Treatment of leukaemia

Stem cell transplants have been successfully used since 1968 to treat patients with leukaemia

Patients with leukaemia first have their own abnormal blood cells destroyed by radiotherapy

Then the patients own bone marrow stem cells are replaced with a transplant (into the bloodstream) from a healthy patient’s bone marrow

If the transplant is successful, then the stem cells will migrate into the bone marrow and begin to produce new, healthy leucocytes

You can learn all about leukaemia treatment by linking here onto Utah Inc:

Utah Genetics

Stem Cells used in medicine: Umbilical Cord Blood

Umbilical cord blood stem cell transplants have been used for treatment of leukaemia.

Unbilical cord blood stem cells are less prone to immune rejection

They are considered a potent resource for transplant therapies

Embryonic Stem cells are pluripotent

What can we use Stem Cells for?

To provide lab-grown human or animal tissue for identifying new treatments for disease (rather than using animals in research)

TO produce new human tissue and organs to replace damaged ones

To repair tissue by stimulating stem cells already in the body

To use stem cells from patients with inherited genetic diseases (e.g. cystic fibrosis, some forms of Parkinson’s disease) to study the disease

To better understand diseases like cancer

To investigate human development

Stem Cell Research is a fast-moving subject

Stem cell grandparents

Brand new sperm

First trial of human embryonic stem cells

Tracheal transplant

Stem cell nobel prize

The Stem Cell Ethical Debate

The Ethical QuestionsUntil recently, the only way to get pluripotent stem cells for research was to remove the inner cell mass of an embryo and put it in a dish. The thought of destroying a human embryo can be unsettling, even if it is only five days old.Stem cell research thus raised difficult questions:• Does life begin at fertilization, in the

womb, or at birth?• Is a human embryo equivalent to a human

child?• Does a human embryo have any rights?• Might the destruction of a single embryo

be justified if it provides a cure for a countless number of patients?

• Since ES cells can grow indefinitely in a dish and can, in theory, still grow into a human being, is the embryo really destroyed?

Ethics and iPS: Problem solved?

With iPS cells now available as an alternative to hES cells, the debate over stem cell research is becoming increasingly irrelevant. But ethical questions regarding hES cells may not entirely go away.Inevitably, some human embryos will still be needed for research. iPS cells are not exactly the same as hES cells, and hES cells still provide important controls: they are a gold standard against which the "stemness" of iPS cells is measured.Some experts believe it's wise to continue the study of all stem cell types, since we're not sure yet which one will be the most useful for cell replacement therapies.An additional ethical consideration is that iPS cells have the potential to develop into a human embryo, in effect producing a clone of the donor. Many nations are already prepared for this, having legislation in place that bans human cloning.

Key Ethical Questions (1)MORALITY AND HUMANITY OF EMBRYOS

1. At what point does an embryo/ blastocyst have full moral status?

2. Is there a ‘moral cut-off’ at 14 days after fertilisation?

3. Does an embryo’s moral status increase as it develops?

Key Ethical Questions (2)1. Is there anything wrong with using spare

embryos left over from fertility treatment?

2. Is it morally justifiable to use embryonic stem cells as a means to an end, if they will provide huge benefits from human health?

3. Should we be using embryonic stem cells at all, if we have the alternatives of stem cell lines derived from umbilical cord blood or induced pluripotential stem cells?

Arguments about embryonic cells

Arguments about Somatic Cell Nuclear Transfer

Arguments about the Moral Status of the

Embryo (1)

Arguments about the Moral Status of the

Embryo (2)

Arguments about the moral status of the

embryo (3)

Arguments about the moral status of the

embryo (4)

Links on ethics related to Stem Cell research

Stem Cell Ethics Factsheet

Ethics and Embryos Factsheet

Are embryos human? – a conversation…