Stem Cells Flashcards
stem cells definition
indefinitely renewing cells that are able to differentiate into different cell types
describe the differentiation of stem cells
stem cells undergo asymmetric division
- one daughter cell is a stem cell
- the other has different genetic instruction + reduced proliferative capacity
- will eventually become a progenitor or a precursor cell (committed to producing more terminally differentiated cells)
totipotent
embryonic membrane + any type of cell in the adult body (zygote)
pluripotent
any cell in the adult body (inner cell mass (ICM) of blastocyst))
multipotent
tissue-specific cell type (hematopoietic; neural; mesenchymal (skeletal)
unipotent
one specific type of adult body cell (e.g. epithelial cells)
human embryonic stem cells (hESCs)
derived from ICM of blastocysts
in the UK, these are isolated from blastysts that were originally created for IVF
- not high enough quality, donated
used in research is highly regulated
adult/ somatic stem cells
replace dying/ damaged cells
identified in many areas of the adult human body (e.g. liver, brain, skin, intestine and bone marrow)
- bone marrow most studied
can be obtained from a tissue sample but difficult to isolate
- difficult to keep them proliferating in culture
haematopoietic; intestinal (multipotent) (located at base of villi); neural stem cells
induced pluripotent stem cells (iPSCs)
a way to make pluripotent stem cells without using embryos
- treated with transcription factors (Oct-3,4, SOX2, c-Myc, KLF4) to switch on genes to include and maintain pluripotency
cancer stem cells
emerging evidence of subpopulation
- exhibit characteristics of cancer and stem cells
- defined by ability to self-renew and to produce cells that differentiate
two hypothesis for why this happens:
arise from normal stem cells
- mutation leads to cancerous stem cells arise from normal somatic ells
- goes bac and acquires stem cell characteristics and malignant behaviours
implications of cancer stem cells
if the stem cells are not killed, then the tumour will repopulate
normal cancer treatments not as effective against CSCs
new immune-based therapeutic treatments targeted at CSCs which allows the majority of the cancerous tumour to be killed and the tumour will then degenerate
- anti-CDE47 therapy
making new blood
research currently ongoing: pluripotent stem cells to make RBCs for blood transfusion
donors + recipients only have to be of the same blood type rather than tissue (fewer = less chance of rejection)
benefit - lives as blood donation systems not needed
- valuable for those living with regular blood transfusions
regenerative medicine - stem cell therapy
bone marror transplant to treat blood disorders such as leukaemia
autologous or allogenic transplant from individual with the same tissue type (HLA type) (family members likely a good match)
can now do from blood sample - peripheral blood stem cell (PBSC), get a course of injections to stimulate the release of stem cells into blood
regenerative medicine - Holoclar
first European medicines agency-approved stem cell treatment
undamaged area of the eye biopsied to isolate limbal stem cells
grown in vitro
a sheet on cornea is produced that can be transplanted onto the eye
can restore sight in the absence of seep corneal stroma damage
stem cell potential
regenerative medicine
growth factors - regulatory molecules that stimulate cell and tissue function through influencing cell differentiation
- lead to a change in biochemical activity, cellular growth and regulate rate of proliferation
easier to mimic normal sequence of differentiation than to reverse (dedifferentiation)
areas they may be helpful in:
- tissue repair
- regenerative medicine
- drug screening
- vehicles for gene therapy
ongoing clinical trials
