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What is Stem cell therapy ? How this
treatment works and with some information of stem
cell treatment .
Stem cell treatment 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.
Research is underway to develop various
sources for stem cells, and to apply stem cell treatments for neurodegenerative
diseases and
conditions, diabetes, heart disease, and other conditions.
With the ability of scientists
to isolate and culture embryonic stem cells,
and with scientists' growing ability to create stem cells using somatic cell
nuclear transfer and
techniques to create induced
pluripotent stem cells, controversy has crept in, both related to abortion politics and to human cloning. Additionally, efforts to market
treatments based on transplant of stored umbilical cord blood have
proven controversial.
Medical uses -
For over 30 years,
bone-marrow have been used to treat cancer patients
with conditions such as leukaemia and lymphoma; this is the only form of stem cell
therapy that is widely practiced.
During chemotherapy, most growing cells are killed by
the cytotoxic agents.
These agents, however, cannot discriminate between the leukaemia or neoplastic
cells, and the hematopoietic stem cells within the bone marrow. It is this
side effect of conventional chemotherapy strategies that the stem cell
transplant attempts to reverse; a donor's healthy bone marrow reintroduces
functional stem cells to replace the cells lost in the host's body during
treatment. The transplanted cells also generate an immune response that helps
to kill off the cancer cells; this process can go too far, however, leading to graft vs host disease,
the most serious side effect of this treatment.
Another stem cell therapy
called Prochymal, was conditionally approved in Canada
It is an allogenic stem therapy based on mesenchymal stem
cells (MSCs) derived
from the bone marrow of adult donors. MSCs are purified from the marrow,
cultured and packaged, with up to 10,000 doses derived from a single donor. The
doses are stored frozen until needed.
The FDA has approved five
hematopoietic stem cell products derived from umbilical cord blood, for the
treatment of blood and immunological diseases.
In 2014, the European
Medicines Agency recommended
approval of Holoclar, a treatment involving stem cells,
for use in the European Union. Holoclar is used for people
with severe limbal stem cell deficiency due to burns in the eye.
Research ;-
Diseases and
conditions where stem
cell treatment is promising or emerging.
Neurodegeneration ;-
Research has been
conducted to learn whether stem cells may be used to treat brain degeneration, such as in Parkinson's, Amyotrophic
lateral sclerosis, and Alzheimer's disease.
Healthy adult brains
contain neural stem cells which divide to maintain general stem
cell numbers, or become progenitor cells. In healthy adult animals,
progenitor cells migrate within the brain and function primarily to maintain
neuron populations for olfaction (the sense of smell). Pharmacological
activation of endogenous neural stem cells has been reported to induce
neuroprotection and behavioral recovery in adult rat models of neurological
disorder.
Brain and spinal cord
injury ;-
Stroke and traumatic brain
injury lead to cell death, characterized by a loss of neurons
and oligodendrocytes within the brain. A small clinical
trial was underway in Scotland
Clinical and animal studies have been
conducted into the use of stem cells in cases of spinal cord injury.
Heart ;-
The pioneering work by Bodo-Eckehard Strauer has now been discredited by the identification
of hundreds of factual contradictions. Among
several clinical trials that have reported that adult stem cell therapy is safe
and effective, powerful effects have been reported from only a few
laboratories, but this has covered old and recent infarcts as well as
heart failure not arising from myocardial infarction. While initial animal
studies demonstrated remarkable therapeutic effects, later clinical trials
achieved only modest, though statistically significant, improvements.
Possible reasons for
this discrepancy are patient age,timing of treatment and the recent
occurrence of a myocardial infarction. It appears that these
obstacles may be overcome by additional treatments which increase the
effectiveness of the treatment[ or by optimizing the
methodology although these too can be controversial. Current studies vary
greatly in cell procuring techniques, cell types, cell administration timing
and procedures, and studied parameters, making it very difficult to make
comparisons. Comparative studies are therefore currently needed.
Stem cell therapy for
treatment of myocardial infarction usually makes use of autologous bone marrow
stem cells (a specific type or all), however other types of adult stem cells
may be used, such as adipose-derived stem cells. Adult stem cell therapy for treating
heart disease was commercially available in at least five continents as of 2007
Possible mechanisms of recovery include’-
·
Generation of heart muscle cells
·
·
Stimulation of growth of new blood vessels to repopulate damaged
heart tissue
·
·
Secretion of growth factors
·
·
Assistance via some other mechanism
·
It may be possible to have
adult bone marrow cells differentiate into heart muscle cells.
The first
successful integration of human embryonic stem cell derived cardiomyocytes in
guinea pigs (mouse hearts beat too fast) was reported in August 2012. The
contraction strength was measured four weeks after the guinea pigs underwent
simulated heart attacks and cell treatment. The cells contracted synchronously
with the existing cells, but it is unknown if the positive results were
produced mainly from paracrine as opposed to direct electromechanical effects
from the human cells. Future work will focus on how to get the cells to engraft
more strongly around the scar tissue. Whether treatments from embryonic or
adult bone marrow stem cells will prove more effective remains to be seen.[
In 2013 the pioneering
reports of powerful beneficial effects of autologous bone marrow stem cells on
ventricular function were found to contain "hundreds" of
discrepancies. Critics report that of
48 reports there seemed to be just 5 underlying trials, and that in many cases
whether they were randomized or merely observational accepter-versus-rejecter,
was contradictory between reports of the same trial. One pair of reports of
identical baseline characteristics and final results, was presented in two
publications as, respectively, a 578 patient randomized trial and as a 391
patient observational study. Other reports required (impossible) negative
standard deviations in subsets of patients, or contained fractional patients,
negative NYHA classes. Overall there were many more patients published as
having receiving stem cells in trials, than the number of stem cells processed
in the hospital's laboratory during that time. A university investigation,
closed in 2012 without reporting, was reopened in July 2013.
Heart ;-
One of the most promising
benefits of stem cell therapy is the potential for cardiac tissue regeneration
to reverse the tissue loss underlying the development of heart failure after
cardiac injury.
Initially, the observed
improvements were attributed to a transdifferentiation of BM-MSCs into cardiomyocyte-like cells Given
the apparent inadequacy of unmodified stem cells for heart tissue regeneration,
a more promising modern technique involves treating these cells to create
cardiac progenitor cells before implantation to the injured area.
Blood-cell formation ;-
The specificity of the
human immune-cell repertoire is what allows the human body to defend itself
from rapidly adapting antigens. However, the immune system is vulnerable to
degradation upon the pathogenesis of disease, and because of the critical role
that it plays in overall defense, its degradation is often fatal to the
organism as a whole. Diseases of hematopoietic cells are diagnosed and
classified via a subspecialty of pathology known as hematopathology.
The specificity of the
immune cells is what allows recognition of foreign antigens, causing further
challenges in the treatment of immune disease. Identical matches between donor
and recipient must be made for successful transplantation treatments, but
matches are uncommon, even between first-degree relatives. Research using both
hematopoietic adult stem cells and embryonic stem cells has provided insight
into the possible mechanisms and methods of treatment for many of these
ailments .
Fully mature human red blood cells may be generated ex vivo by hematopoietic stem
cells (HSCs), which
are precursors of red blood cells. In this process, HSCs are grown together
with stromal cells, creating an environment that
mimics the conditions of bone marrow, the natural site of red-blood-cell
growth. Erythropoietin, a growth factor, is added, coaxing the stem
cells to complete terminal differentiation into red blood cells. Further research into this technique should have potential
benefits to gene therapy, blood transfusion, and topical medicine.
Baldness; -
Hair follicles also contain stem cells, and
some researchers predict research on these follicle stem cells may lead to
successes in treating baldness through
an activation of the stem cells progenitor cells. This treatment is expected to
work by activating already existing stem cells on the scalp. Later treatments
may be able to simply signal follicle stem cells to give off chemical signals
to nearby follicle cells which have shrunk during the aging process, which in turn respond to
these signals by regenerating and once again making healthy hair. Most
recently, Aeron Potter of the University of
California has claimed
that stem cell therapy led to a significant and visible improvement in
follicular hair growth .
Missing teeth
In 2004, scientists at King's College London discovered a way to cultivate a
complete tooth in mice[39] and were able to grow bioengineered teeth stand-alone in
the laboratory. Researchers are confident that the tooth regeneration technology can be used to grow live
teeth in human patients.
In theory, stem cells taken
from the patient could be coaxed in the lab into turning into a tooth bud
which, when implanted in the gums, will give rise to a new tooth, and would be
expected to be grown in a time over three weeks.
It will fuse with the
jawbone and release chemicals that encourage nerves and blood vessels to
connect with it. The process is similar to what happens when humans grow their
original adult teeth. Many challenges remain, however, before stem cells could
be a choice for the replacement of missing teeth in the future.
Research is ongoing in
different fields, alligators which
are polyphyodonts grow up to 50 times a successional
tooth (a small replacement tooth) under each mature functional tooth for
replacement once a year.[]
Deafness
Heller has reported success in re-growing
cochlea hair cells with the use of embryonic stem cells.
Blindness and vision
impairment ;-
Since 2003, researchers
have successfully transplanted corneal stem cells into damaged eyes to restore
vision. "Sheets of retinal cells used by the team are harvested from
aborted fetuses, which some people find objectionable." When these sheets
are transplanted over the damaged cornea, the stem cells stimulate renewed repair, eventually
restore vision.[The latest such development was in June 2005, when researchers
at the Queen Victoria
Hospital of Sussex, England were able to restore the sight of
forty patients using the same technique. The group, led by Sheraz Daya, was able to successfully use
adult stem cells obtained from the patient, a relative, or even a cadaver. Further rounds of trials are ongoing.
In April 2005, doctors in
the UK
The
University Hospital of
New Jersey
In 2014, researchers
demonstrated that stem cells collected as biopsies from donor human corneas can
prevent scar formation without provoking a rejection response in mice with
corneal damage.
In January 2012, The Lancet published
a paper by Steven Schwartz, at UCLA's
Jules Stein Eye Institute, reporting two women who had gone legally blind from
macular degeneration had dramatic improvements in their vision after retinal
injections of human embryonic stem cells.
Diabetes ;-
Diabetes patients lose the function of insulin-producing beta cells within
the pancreas. In recent experiments, scientists have been able to coax
embryonic stem cell to turn into beta cells in the lab. In theory if the beta
cell is transplanted successfully, they will be able to replace malfunctioning
ones in a diabetic patient.
Transplantation;-
Human embryonic stem cells
may be grown in cell culture and stimulated to form insulin-producing cells
that can be transplanted into the patient.
However, clinical success is highly dependent
on the development of the following procedures:
·
Transplanted cells should proliferate
·
·
Transplanted cells should differentiate in a site-specific
manner
·
·
Transplanted cells should survive in the recipient (prevention
of transplant rejection)
·
·
Transplanted cells should integrate within the targeted tissue
·
·
Transplanted cells should integrate into the host circuitry and
restore function
Orthopaedics; -
Clinical case reports
in the treatment orthopaedic conditions
have been reported. To date, the focus in the literature for musculoskeletal
care appears to be on mesenchymal stem cells. Centeno et al. have published MRI
evidence of increased cartilage and meniscus volume in individual human
subjects.[52][53] The results of trials that include a large number of
subjects, are yet to be published. However, a published safety study conducted
in a group of 227 patients over a 3-4 year period shows adequate safety and
minimal complications associated with mesenchymal cell transplantation..
Wakitani has also published a small case
series of nine defects in five knees involving surgical transplantation of
mesenchymal stem cells with coverage of the treated chondral defects.
Wound healing ;-
Stem cells can also be
used to stimulate the growth of human tissues. In an adult, wounded tissue is
most often replaced by scar tissue, which is characterized in the
skin by disorganized collagen structure, loss of hair follicles and irregular
vascular structure. In the case of wounded fetal tissue, however, wounded
tissue is replaced with normal tissue through the activity of stem cells. A possible method for
tissue regeneration in adults is to place adult stem cell "seeds"
inside a tissue bed "soil" in a wound bed and allow the stem cells to
stimulate differentiation in the tissue bed cells. This method elicits a
regenerative response more similar to fetal wound-healing than adult scar
tissue formation. Researchers are
still investigating different aspects of the "soil" tissue that are
conducive to regeneration.
Infertility ;-
Culture of human embryonic
stem cells in
mitotically inactivated porcine ovarian fibroblasts (POF) causes differentiation
into germ cells (precursor
cells of oocytes and spermatozoa), as evidenced by gene expression analysis.
Human embryonic stem cells
have been stimulated to form Spermatozoon-like cells, yet still slightly
damaged or malformed. It could potentially
treat azoospermia.
In 2012, oogonial stem cells were isolated
from adult mouse and human ovaries and demonstrated to be capable of forming
mature oocytes. These cells have the
potential to treat infertility.
HIV/AIDS; -
Destruction of the immune system by the HIV is driven by the loss of
CD4+ T cells in the peripheral blood and lymphoid tissues. Viral entry into
CD4+ cells is mediated by the interaction with a cellular chemokine receptor,
the most common of which are CCR5 and CXCR4.1 Because subsequent viral
replication requires cellular gene expression processes, activated CD4+ cells
are the primary targets of productive HIV infection.
Recently scientists have been investigating an alternative
approach to treating HIV-1/AIDS, based on the creation of a disease-resistant
immune system through transplantation of autologous, gene-modified
(HIV-1-resistant) hematopoietic stem and progenitor cells (GM-HSPC).
Further informations
;-
What are stem cells?
The body is made up of about 200 different kinds of
specialized cells such as muscle cells, nerve cells, fat cells and skin cells.
All specialized cells originate from stem cells. A stem cell is a cell that is
not yet specialized. The process of specialization is called differentiation
and once the differentiation pathway of a stem cell has been decided, it can no
longer become another type of cell.
Stem cells have different levels of potential. A stem
cell that can become every type of cell in the body is called pluripotent and a
stem cell that can become only some types of cells is called multipotent.
Where are stem cells found?
Stem cells are found in the early embryo, the fetus,
amniotic fluid, the placenta and umbilical cord blood. After birth and for the
rest of life, stem cells continue to reside in many sites of the body,
including skin, hair follicles, bone marrow and blood, brain and spinal cord,
the lining of the nose, gut, lung, joint fluid, muscle, fat, and menstrual
blood, to name a few. In the growing body, stem cells are responsible for
generating new tissues, and once growth is complete, stem cells are responsible
for repair and regeneration of damaged and aging tissues.
When you bank your newborn's cord blood, you preserve
a unique biological resource that is like a "repair kit" for your
child, and possibly another immediate family member.
Uses of Stem Cells
Stem cells have been used to treat over 80 diseases, including
malignancies, blood disorders and immune deficiencies.
Stem cells work by providing new cells
to replace damaged, diseased, or defective cells.
- Stem
cells can actively divide and produce new blood cells within two to six
weeks.
- will
stimulate regeneration of the blood components in the bone marrow damaged
by high doses of chemotherapy or radiation. This often occurs in leukemia
or lymphoma, for example, when the bone marrow is diseased and must be
destroyed.
- Stem
cells can correct defects in children with inherited or inborn errors of
metabolism by replacing these defective cells in the bone marrow with new,
non-defective cells.
- Stem
cells can produce other types of cells that travel to the brain, liver,
and other organs. Research is currently being done on these other uses.
Many clinics offering stem cell
treatments make claims that are not supported by a current understanding of
science
Stem cells have tremendous
promise to help us understand and treat a range of diseases, injuries and other
health-related conditions. Their potential is evident in the use of blood stem
cells to treat diseases of the blood, a therapy that has saved the lives of
thousands of children with leukemia; and can be seen in the use of stem cells
for tissue grafts to treat diseases or injury to the bone, skin and surface of
the eye. Important clinical trials involving stem cells are underway for many
other conditions and researchers continue to explore new avenues using stem
cells in medicine.
There is still a lot to
learn about stem cells, however, and their current applications as treatments
are sometimes exaggerated by the media and other parties who do not fully
understand the science and current limitations, and also by “clinics” looking
to capitalize on the hype by selling treatments to chronically ill or seriously
injured patients. The information on this page is intended to help you
understand both the potential and the limitations of stem cells at this point
in time, and to help you spot some of the misinformation that is widely
circulated by clinics offering unproven treatments.
It is important to
discuss these Nine Things to Know and any research or information you
gather with your primary care physician and other trusted members of your
healthcare team in deciding what is right for you.
Currently, very few stem
cell treatments
have been proven safe and
effective
There is something to lose
when you try
an unproven treatment
Different types of stem cells
serve
different purposes in the body
The same stem cell
treatment is unlikely
to work for different
diseases or conditions
The science behind a
disease should
match the science behind
the treatment
Cells from your own body
are not
automatically safe when
used in
treatments
Patient testimonials and
other marketing
provided by clinics may be
misleading
An experimental treatment
offered for sale
is not the same as a clinical trial
9
What diseases and conditions can be treated with stem cells?
Reviewed by:
The
most well-established and widely used stem cell treatment is the
transplantation of blood stem cells to treat diseases and conditions of the
blood and immune system, or to restore the blood system after treatments for
specific cancers. The US National Marrow Donor Program has a full list of diseases treatable by blood stem cell
transplant. More than 26,000 patients are treated with blood
stem cells in Europe each year.
Since
the 1970s, skin stem cells have been used to grow skin grafts for patients with
severe burns on very large areas of the body. Only a few clinical centres are
able to carry out this treatment and it is usually reserved for patients with
life-threatening burns. It is also not a perfect solution: the new skin has no
hair follicles or sweat glands. Research aimed at improving the technique is
ongoing.
Currently, these are the
only stem cell therapies that have been thoroughly established as safe and
effective treatments. Some other applications of stem cells are being
investigated in clinical trials, including the use of stem cells to regenerate
damaged tissues – such as heart, skin, bone, spinal cord, liver, pancreas and
cornea – or to treat blood or solid-organ cancers. The majority of these trials
are using mesenchymal stem cells, which are derived from
sources such as fat tissue, bone marrow and connective tissue. A small
proportion of the trials are using blood
stem cells.
Among the most advanced clinical trials are those that aim to treat
certain bone, skin and corneal diseases or injuries with a graft of tissue
grown from stem cells taken from these organs. For example, stem
cells from the eye can
be used to grow a new cornea for patients with certain kinds of eye damage.
This has already been shown to be safe and effective in early stage trials.
However, further studies with larger numbers of patients must be carried out
before this therapy can be approved by regulatory authorities for widespread
use in Europe .
Stem
cell treatments are all specialist procedures. They should be performed only in
specialized centers authorized by national health authorities.
All
treatments should be considered experimental until they have successfully
passed all the stages of clinical trials required to test a new therapy
thoroughly. Only then will the treatment be approved for widespread use.
The process by which
science becomes medicine is designed to minimize harm and maximize
effectiveness
UpDown
Stem cell researchers are
making great advances in
understanding normal
development, figuring out what goes wrong in
patients. They still
have much to learn, however, about how stem cells
work in the body and
their capacity for healing. Safe and effective
treatments for most
diseases, conditions and injuries are in the future.
( sources – collected
from internate )
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