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You may have heard about stem cells and their ability to fix everything from broken bones to Parkinson’s Disease. But if they’re that good, why is there so much controversy over stem cell research, and where does New Zealand stand on the issue? Family Health Diary reports.

Anyone with a passing interest in health will have heard the hype about stem cells – how they might offer cures to motor neuron disease or help the paralysed walk again.

Yet here and abroad, some aspects of stem cell research continue to rouse debate, with many arguing the ends don’t justify the means.
 

The issue is so sensitive that New Zealand’s guidelines on stem cell research are, as they stand, somewhat restrictive. These, however, are up for review.

Everything could change pending the outcome of a current public consultation that could see the doors opened to stem cell research of a much wider scale.

THE ETHICAL DEBATE
So, what’s the controversy all about? And, indeed, what’s so special about stem cells? Well, here’s a little perspective.

In New Zealand, research using adult stem cells is already taking place, with the general blessing of the general public.

But it’s another branch of stem cell research that’s raising moral alarm – and that’s the research involving human embryos.

Though stem cells can be obtained from other sources (umbilical cord blood, adult tissues, or foetuses from pregnancy terminations), those sourced from embryos (around 4-7 days old) are considered the holy grail of medical research. But, with their use comes sacrifice.

Professor Gareth Jones from the University of Otago’s Department of Anatomy and Structural Biology says the process of obtaining stem cells from embryos requires destruction of the embryo.

The fact that, typically, only ‘surplus’ embryos from IVF clinics are used, is cold comfort to some. “For those who believe that a fertilised egg represents the start of human life, embryo destruction is very distressing,” he says.

There are also concerns regarding embryonic stem cell research when linked to cloning technology.

But, for Professor Jones, the positives appear to outweigh the negatives. He says stem cells could enable scientists “to better understand the developmental processes of the human body – what goes right and wrong”. From this perspective, the potential benefits of their use may be “unlimited”.

WHAT ARE STEM CELLS?
What makes stem cells so remarkable is that they retain the ability to divide and produce copies of themselves or any other cell that makes up the human body.

That means stem cells have the potential to replace dead brain cells, malfunctioning pancreas cells, or even damaged skin cells.

Researchers suspect stem cells could be used to repair diseased or damaged tissue in patients – offering in the future an alternative to transplants with donated organs.

But the focus for now is to find out how stem cells work, how they multiply, and whether they can be multiplied for use in transplantation and other therapies.

For now, it’s considered embryonic stem cells have a greater potential than adult stem cells.


Stem cell research offers hope to paraplegics, among many other people

BENEFITS OF STEM CELLS IN THE FUTURE
In the short-term, stem cells could be used to…
  • Understand the developmental pathways that lead to the birth of normal, healthy human beings.
  • Identify the cause of fertility problems, including recurrent miscarriages and the birth of children affected by developmental disorders.
In the long run, stem cells could be used to treat…
  • Heart disease by regenerating healthy tissue in the heart.
  • Juvenile onset diabetes, by forming insulin-producing cells in the pancreas.
  • Alzheimer’s disease, multiple sclerosis and stroke, by regenerating brain cells and nervous system cells.
  • Burns, by growing new skin.
  • Cancer, by helping us understand how cells multiply and divide in an uncontrolled way.

NEXT STEPS
Current New Zealand legislation only allows for embryonic stem cell research to be carried out on imported stem cells (ie. those sourced from human embryos in other countries).

That capacity, however, could be extended depending on the outcome of the current consultation by the Advisory Committee on Assisted Reproductive Technology (ACART).

Professor Gareth Jones, for one, thinks it’s likely New Zealand will adopt a more permissive stance, like that of Australia’s, where surplus embryos from IVF clinics can be used for research, or even that of the United Kingdom’s, where embryos can be specifically manufactured for research.

But regardless of the position we adopt, it will be a long time before research translates to any cures or specific applications, he says. Small milestones are more likely. “With spinal cord research, a ‘halfway house’ is likely. Rather than stem cells being used to enable paraplegics to walk, perhaps they will enable them to regain bladder function.”

Associate Professor Andrew Shelling, head of the Medical Genetics Research Group at the University of Auckland and also a member of ACART, agrees we’re a “number of years away from fully understanding stem cells and how they work”.

For most of us, that means we might never fully appreciate the hype about stem cells. But it’s reassuring to know that our children might.

CELLS, STEM CELLS, AND EMBRYONIC STEM CELLS
  • What is a cell? Cells are the basic building blocks of all living things. All cells start out as ‘generalists’, containing all the genetic information needed for our body to grow, develop and function. But as a human embryo develops, most cells ‘differentiate’ and take on specific functions, becoming kidney cells, nerve cells, brain cells or blood cells. This means they change from ‘generalists’ to ‘specialists’, and only the genes needed to carry out their specialist function continue to work.
  • What is a stem cell? Stem cells are cells that retain the ability to grow into different kinds of healthy tissue. They can divide and produce copies of themselves or transform into other, more specialised, cells.
  • Why embryonic stem cells? While there are stem cells in a baby’s umbilical cord and in adult tissue, many experts believe embryonic stem cells are the most promising with respect to understanding human development and disease.


Types of Stem Cells:
There are four main types of stem cells being investigated for their potential use in the medical arena.
There are important differences in the way each type of stem cell is collected and ethical issues that apply to their use.
    

Embryonic Stem Cells:
  • Obtained from embryos around 4-7 days old.
  • Can form virtually any type of cell found in the human body.
  • Can be cultured (grown in a laboratory) in large numbers, and kept viable for a long time.
  • It is these two factors – their versatility and ease of culture – that makes embryonic stem cells the main focus for many researchers.

Embryonic Germ Stem Cells (also called foetal stem cells)  
  • Taken from a developing foetus between 6-9 weeks in gestation.
  • Similar to embryonic stem cells in that they can develop into any cell type, but because they don’t survive for as long in a laboratory, they are less suitable for research.
  • There are ethical issues with using cells from terminated pregnancies at a later stage of gestation.

Cord Blood Stem Cells
  • Come from the umbilical cord. Umbilical cord blood is rich in stem cells that can develop into different types of blood cells as well as cells of the immune system.
  • Because these cells are immature compared to adult blood cells they are less likely to cause an immune reaction if used in transplants later in life. 
  • Umbilical cord stem cells can currently be used to treat more than 45 cancers, immune deficiencies and genetic disorders.
  • Researchers are excited about their potential for further uses in the future.
  • New Zealand’s first cord blood bank was established in 2003 to store blood collected from the umbilical cord of a newborn baby shortly after birth.
  • Under current New Zealand legislation, only the baby from whom the umbilical cord blood stem cells were taken can be treated with those stem cells.

Adult Stem Cells
  • Found in many parts of the adult human body, such as the spinal cord, liver, brain, retina, cornea and the lining of the blood vessels.
  • Adult stem cells appear to exist primarily to maintain and repair the tissue in which they are found, ie. skin stem cells can form new skin cells. They, therefore, appear less versatile than embryonic stem cells.
  • Researchers hope that adult stem cells will prove to be as useful as embryonic stem cells in generating tissue for transplants.

by Jenny Cade and Aileen Nakhle


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