During the journey of conception till birth, the
body structure of any species is generated through biological processes.
In Human, development of a mature fetus from a
zygote undergoes multiplication of cells and their subsequent controlled and
co-ordinated tissue growth, movement, and differentiation. In addition, it also
crosses phases of degeneration and regeneration of tissues and organs till a complete
Man.
Regeneration continues throughout human life. As a
natural process, it is speedy healing of any injury or ill developed body organs
by de-differentiation & development of these cells into new similar tissue.
Organ such as liver is known to regenerate easily.
But every organ of our body cannot regenerate
naturally. Inability to regenerate the responses to injuries or diseases
threats our life.
Regenerative Medicine is directed to heal fractured
bones, burns, blindness, deafness, damage of muscle, nerve, blood vessel etc.
to extend lifespan. Age-related degeneration & damage can also be repaired
by such therapy.
The therapy uses patient's own tissue from other
part of body to repair the injured site. Similarly, biomaterials, metallic
& plastic types are also used to repair tissue damage depending upon the
nature of trauma. Often due to bio-incompatibility these materials are rejected
by the body & creates great problem in healing the damage.
Body itself has a great role in regenerative
process. In case of trauma damaged tissues are replaced naturally by the help
of primitive progenitor cells or Stem cells of the body.
Stem cells are broadly categorized in two types: Embryonic
stem cells & Adult stem cells.
The embryonic stem cells (ESC) are the inner cell
mass of an embryo at blastocyst stage, which has the ability to differentiate &
develop into any cell type of our body. These cells have unlimited capacity to
self-renewal in culture.
Their abilities were explored only when the cells
were available to manipulate in laboratories. The major contributor of these
stem cells study is the In Vitro Fertilization (IVF) as an Assisted Reproductive
Technology.
IVF generates numerous embryos for the treatment of infertility.
Usually 2-3 embryos fertilized in vitro are transferred into uterine cavity per
cycle. If conception takes place, the
leftover embryos not necessary for those couples are usually donated for
research purposes. Thereby, extensive studies are underway on the use of these
embryonic cells in regenerative medicine & cell therapy.
In the mean time, there have been controversies
about the use of such embryonic cells for research. Some belief that use of
embryonic cells destroys the embryo which could have been born as a Human.
Others belief that artificially fertilized embryos unless implanted in the
uterus have no legal status & they are not even part of a human being. However,
the research is also a means of the welfare of mankind.
The embryonic stem cells are being cultured & engineered
into the necessary cell type. For example, development of structurally &
functionally similar cells of pancreas which can produce insulin can save life
of many suffering from Type1 diabetes (Insulin dependant type). In this
condition the cells of pancreas are diseased or damaged, cannot produce insulin
to digest the glucose containing meal, hence glucose level rises in blood. Thereby
diabetes develops which is controlled only with the help of insulin injections
life-long.
Adult Stem cells are localized within wide variety
of tissue & organ such as skin, muscle, bone marrow, blood etc. with
limited ability to divide, differentiate & self renewal into other cell
type. The hematopoietic cells which develop blood cells are also adult stem
cells. They have great role in tissue regeneration & repair. In tissue
damage, they migrate to the site of injury & differentiate into blood
cells, cartilage, bone, fat cells & even outer layer of blood vessels to
repair the damage.
Stem cell based therapies currently available
adult-derived stem cells are from bone marrow and skin. Little is known about
the degree of their plasticity and there are difficulties in purifying and
culturing these cells.
Regenerative medicine researches have found similar
ability as embryonic stem cells of differentiation & development in
Umbilical Cord blood cells. In animal model it has been reported that these
cells can be engineered to produce many cell types. In comparison to embryonic
stem cell, availability of the cord blood cells is easier. Due to its easy
availability, now -a -days, cord blood is used in a variety of conditions as an
alternative of bone marrow for transplant, in stroke, in heart diseases etc.
The Human umbilical cord blood stem cells multiply
fast & increase their number in laboratory culture. These cells can also
change into muscle, liver, bone, nerve, skin cells etc. according to culture
conditions. However, culturing these tissues for therapy is not so easy. It
utilizes high-tech such as Reverse Transcription–Polymerase Chain Reaction
(RT-PCR), Immunostaining and imaging, Flow cytometry analysis techniques etc.
By this method, the cultured specific cells can be
isolated, stored & transplanted in need. In case of liver disease, they can
be used for replacement of liver cells.
Burns or skin diseases use skin grafts for
treatment. These grafts if developed from patients own stem cells there is no
danger of tissue rejection.
Researchers have found that bone disease such as
osteoporosis can be treated using umbilical cord blood cells.
In neurological diseases, the damaged nerve can also
be repaired by these cells.
These cells also have profound role in Cardiology
for repairing heart tissue & blood vessels. Extensively concentrated areas
of medical research include Diabetes, Parkinson's disease, Alzheimer's & Cancer.
The disadvantage on the use of cord blood is that it
contains not only stem cells but also the non-stem cells with specific
immunological properties may sometimes be rejected with severe immunological
reaction. More attention is on that line to make these cells easily acceptable
to any individual.
Researches are underway around the world to make
proper use of the cord blood cells. Large scale expansions of these stem cells
into numerous cell types are produced by culture. They are packed & stored
at an appropriate temperature before use. These cells have a very good
International market & are promoting medical industries. There is a great
need of such activities in this country as well. At least cord blood storage
& transfusion would have saved a lot of life.
Moreover, the technique would be of a great interest
to all the Medics. In India, there are many such institutions where
regenerative medicine has been well advanced. The potential of such activities
centre could be the Biomedical engineering institutions where tissue
engineering can be expanded with foreign collaborations if our hospitals
demand.
In the last decade all the miracles of stem cells were
highlighted. This decade some utilization of stem cells is underway. In coming
decade we may be using stem cells in every disease conditions as tablets, ointments,
injections etc. & reduce the use of chemicals.
The ability of stem cells seems much more than what
we know till date. We can assume that stem cell therapy & gene therapy may
even extend Human life expectancy.
