totipotent stem cells

ok, so you're reading the newspaper, or you're watching the news and they're talking about some new medical technology, some breakthrough treating congestive heart failure or regrowing muscle tissue in wounded soldiers. i bet you that that story is going to mention that this new type of therapy uses stem cells. and i bet you, like most people, are going to listen along and just go [nods agreeably] without actually knowing what stem cells are, because who has time to know what stem cells are?!? today, we are making time. you have lots of different types of cells in your body. you've got muscle cells, and skin cells, and liver cells, and brain cells,

most of these cells have to be replaced every once in a while. your tastebuds, for instance, are replaced every 10 days or so, skin cells are replaced every couple of weeks, and liver cells turn over every 300-500 days. the cells that are doing the replacing of the old cells, and the repairing of the damaged tissue are adult stem cells, also called somatic stem cells. the different sort of cells, skin cells, liver cells, retina cells,muscle cells and intestine cells, they all have very specific jobs and they're built in very specific ways to do those jobs. different shapes, sizes, contents, mean you can't just stick a muscle cell into adamaged liver an expect it to start breaking down your alcohol for you. somatic stem cells, on the other handhaven't decided what the heck they're gonna be. they're undifferentiated. they haven'tspecialized yet.

like a college freshman, or, let's face it, a recent collegegraduate. they have no idea what they're going to do with their lives. but just like there are different types of college graduates, there are different types of adultstem cells. some can become more different kinds of things thanothers. pluripotent adult stem cells can become many different types of cells all overthe body, however, they're really hard to track down because there are so few ofthem in each organ or tissue. there also multipotent adult stem cells which are more common in the body, but restricted in the kind of cell they can become it is kinda like the difference between graduating from trade school where you have been trained to do a few different possible jobs and graduating with a degree in philosophy or something

equally unprepared for all jobs so yeah , stick a pluripotent cell in a damaged liver and it just happily becomes a liver cell pretty cool but there are some even better types of stem cells to be had embryonic stem cells which are also pluripotent these are the cells inside a human embryo when it is a blastocyst basically just a tiny nugget of human cells four or five days old

which is destroyed in the process of removing the stem cells from inside it these embryonic cells are obtained from in vitro fertilization clinics that fertilize eggs outside of the mother's body for couples who are having trouble conceiving naturally, these clinics have some left over fertilized eggs so with the donor's permission they are given to scientists doing stem cell research now the main advantage of the embryonic stem cells is that while adult stem cells can be grown in culture for time meaning they can be made to multiply over and over in a nutrient solution they can't grow as long or as fast as the embryonic stem cells

which can be maintained indefinitely into the right conditions after just six months in culture , a single wad of 30 embryonic stem cells will have yielded millions of stem cells which can go on to develop pretty much into any type of cell in the body also adult stem cells if used in some sorts of transplant therapies are more likely to be rejected than embryonic stem cells stem cell research is currently pretty hopin embryonic stem cells are being used by researchers all over the world to figure out how to repair or replace damaged cells and organs and create new drugs but regulations have taken their toll there are only about thirty five stem cell lines or families of identical pluripotent stem cells that are available for federally funded research in america

whereas europe has a couple thousand so there , now you never have to " nod along " your way through another news report about stem cells again thanks for watching this episode of scishow if you have any questions , comments or suggestions you can find us on facebook and twitter or of course down in the comments below and if you wanna keep getting smarter with us here in scishow you can go to youtube.com/scishow and subscribe transcription by dr.a

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the stem cell

what's the right thing to do? what's the appropriate way about goingabout this? does this question have any answer? over the last several years, stem cellresearch has been associated with a lot of enthusiasm, but it's also beenassociated with a lot of ethical issues. recently we've seen a lot attention and alot of scientific excitement over ips, or inducedpluripotent stem cell research. this is very exciting science. >> you can take a skin cell like acheek swab

or you know medical waste from a procedureand take those cells, give them a little sort of fountainof youth cocktail, and turn them into something that is likeembryonic stems cells. that, that can turn into it is prettypotent that can turn into any cell in the humanbody. science by its nature moves very quicklyand unpredictably and generally out of thepublic spotlight. so, it's generally not until after the science the initial science has alreadybeen

produced and published that policy makersor the general public actually hear about it. when president obama issued his executiveorder rescinding the bush administration orderhe directed the national institutes of health todevelop guidelines for federal funding ofembryonic stem-cell research. and it's dramatically increased the amountof stem-cell research that's actually funded here inthe us. so the national academy's guidelines,which were the first set of

guidelines out there at all in the unitedstates for governing stem-cell research, arose out of theinterest of scientists who understood very clearly that this was a, a sociallycontroversial area of science. and in the absence of any federalregulation, went to the national academies and said, pleasedevelop guidance, develop a, a system under which we can operate sothat we are accountable and so that we prevent,you know, bad outcomes. [music] scientists go into science to do sciencenot to do law, so we developed

a project, or looking at internationalcollaboration in stem cell research in the context ofthis highly varied landscape of, of policies governing stemcell research. and this turned out to be the beginning ofwhat we now call the hinxton group. which is an international consortium of scientists, ethicists, policy makers,lawyers, philosophers who are interested in as i said before, fostering ethically andscientifically defensible research. >> some of the most heated ethicalcontroversies

related to embryonic stem cell researchhave related to the fact that embryos need to be destroyed in order to create embryonicstem cell lines. professional groups were coming into thepicture saying, we know that there are ethical issuesinvolved. we know that there are different laws locally, nationally and internationally,and they wanted to provide scientists with a way ofnegotiating among these different laws and, andethical norms.

under the national academy of sciences,this is known as an escrow, nothing to do with themortgage crisis. but the embryonic stem cell researchoversight committee for the isscr, the international society of stem cellresearch, they recommend a scroc. a stem cell research oversight committeebecause they took on a larger task of not just looking at the ethical issues with embryonic stemcell research, but those of all sorts of stemcells. at hopkins, we obviously took notice ofthese major national and

international guidelines, assembled acommittee of people from across the university, given that we do a considerable amount of stemcell research and made a decision to proceed with establishing anscroc here at johns hopkins. we constructed a multidisciplinary committee that includes scientists,includes ethicists, attorneys and non institutionalmembers so we have relevant expertise in the room to considerthe range of issues that are associated with stemcell research.

if a scientist at john hopkins wants to doresearch involving human embryonic stem cells, either research directed at deriving new human embryonic stem celllines or doing laboratory work involvingexisting human embryonic stem cell lines, then she or he has to come to thescroc for approval for that research. >> what bioethicist and, and folks likemyself who are scientists, who are doing work in ethics and policy try to dois, to get ahead of that curve a bit. so to try to forecast, by speaking withscientists and working with scientists, try to identify what arethose issues that are

coming down the pike scientifically, thatare gonna be of interest and potentially of concern to the generalpublic and to policymakers. and to try to be proactive aboutdeveloping guidance for how policymakers and the public might regard or regulate oroversee emerging technologies. >> being in the field of bioethics isfantastic. you get to take the hardest questions, thethings that people talk about at the dinner tableor at a cocktail party and really study them,really try to figure out what's the right thingto do.

what's the appropriate way about goingabout this. [music].

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tem cell

our expectations for the first treatment,we really were hoping that he would talk, because at the age of 9 flynn couldn't talk.that was our main goal, and main hope was for flynn to be able to talk. my name is frazer rigby, and this is my sonflynn rigby, and we are from australia. cairns, australia. flynn was born at 23 and a half weeks gestation,so extremely premature. we knew there would be big problems because he was born so early,but we hoped that, over time, everything would be fine but - obviously they weren't. flynn'severy stage of his development, was severely delayed, so we knew that we had to do something.whatever we could to help him.

his condition is a result of his cerebellumnot developing, and also those lesions and damage to the brain. as a result of that finemotor skills have been severely affected. speech has been the major problem. he wasable to walk, he was able to reach those milestones, they were delayed, but speech has been onethat up until the age of nine, flynn, he could not talk. the transformation in flynn from before toafter the stem cell treatment has been significant. flynn could not speak and after the treatmenthe could talk. his fine motor skills, in terms of just walking, and riding a bike now, andswimming, and interacting with his peers and

wanting to be a part of society has been asignificant change in flynn. his reading of books, his comprehension has improved andwe are hoping that it will continue to do so. our experience at better being hospital, flynny,has been very good. the staff have been fantastic, the facilities are great, very very similarto our western facilities at home... and it's been very organized and so we've been veryhappy. haven't we flynn? we would definitely recommend stem cell treatmentto people who are looking for some success or potentially some improvements in all typesof conditions in australia. certainly, it has helped flynn, and i'm sure that it couldhelp many people

if they did choose to go down that path. just for us, our journey has been, has beenphenomenal. phenomenal, you know and we've had community support. and the success, weknow that it's all, the majority of that has to do with the stem cells treatment.

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study of stem cells

[ music ] >> we all regrow parts of ourbody, your hair, your nails. you probably do not know we alsocan regrow part of our brain. the nerve cells areregenerated every day. actually, we have over athousand new neurons every day in our brain for our lifetime. my name is hongjun song. i'm the director ofthe stem cell program. i develop new technologies andapply them to study stem cells

in humans and the animals. i discovered where stemcells are, how they grow, and how they contributeto brain functions. i also study how stem cellare affected by experience, good ones or bad ones,and how they are affected by medical treatments suchas antidepressant treatments and chemotherapy. i hope to harness our ownregeneration potential to improve learning andmemory and help treat injuries

and brain disorders suchas epilepsy and depression.

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stern cell

- [voiceover] so, let megive you an analogy, here. when you were still anadorable little baby, you were just bursting with potential. you could decide to be a pilot, or a doctor, or a journalist. you had the potential to specialize into all sorts of different careers, and as you got a bit older,you got more and more committed down a certain pathway,

and the decisions that you made moved you further and furtheralong this pathway, right? well, it turns out that stemcells operate in a similar way, going from unspecializedto more specialized as they get older. so, let me show you what i mean by that over the course of this video. and let's actually startback at the zygote, here, the cell that resultswhen sperm and egg fuse

because that's really where our stem cell story kinda begins. so, the zygote starts to divide, right, by mitosis until it reachesthe blastocyst stage, this hollow ball of cellshere is called a blastocyst. and here, things start to geta little bit more interesting. so, in a blastocyst, there'sthis little grouping of cells down in here, referred toas the inner cell mass. and this is a really speciallittle bunch of cells

that go on to become the embryo. so, these are called stem cells. and what they can do as stem cells is they can specialize intoseveral other cell types. so, we actually call thempluripotent stem cells. pluri meaning several and potent referring to these stem cells' ability to actually do this differentiation. so, during development,these inner cell mass

pluripotent stem cells can differentiate into any of the more than200 different cell types in the adult human body whengiven the proper stimulation. so, it's kind of incredible to think that every single cell in your body can trace its ancestry back to this little group of stem cells, here. and actually, if you ever hear anyone talking about embryonic stem cells,

these are the ones they're referring to, these icm stem cells. so, is this the only placewe can find stem cells, here in the developmental structures? we used to think so, but, it turns out that in mammals, there aretwo main types of stem cells. embryonic stem cells that we just saw and somatic stem cells whichare found in every person. so, the embryonic stem cellsare used to build our bodies,

to go from one cell totrillions of specialized cells, and the somatic stem cells are used as sort of a repair system for the body, replenishing tissuesthat need to be replaced. and they can't repair everything, but, there's a lot of every day repairs that can happen because of our stem cells. so, in skin, for example... this outside layer is the partof our skin that we can see

and that we can touch, right? and it's made of these waterproof, pretty rugged epithelialor skin cells and interestingly, althoughthey are pretty rugged, you're constantlyshedding these skin cells. they actually just sort offall off or get rubbed off during every day activities like when you're putting your clothes on. and then, the ones from underneath them

just sort of move up and take their place. so, you shed them and you lose almost 40,000 of them per hour. so, if we wanna have anyhope of keeping our skin, we kinda need a way toreplace these cells, and that's where stem cells that live in our skin come in. actually, our skin cells are shed and replaced so often,that it only takes a month

for us to have a completely new skin. like, literally onemonth, entirely new skin. it's outrageous. anyway, deep within our skin, there's this layer of stem cells called epidermal stem cells, and their job is to becontinually dividing. so, you can see themdividing, here, dividing, dividing, dividing, and makingnew skin cells that go on

to migrate upward as themultiple layers of our skin. and their goal is to eventually replace these ones up here on the outside that get damaged or worn out and fall off. so, it's this kind of activity here which show off our stem cells' role as our regenerative cells. now, lemme just highlighta few differences between our mature skin cells over here

and our stem cells down here. they are very different. mature cells are notthe same as stem cells, and this principle goesfor really any mature cell versus any stem cell. so, the mature cell isalready specialized, it already has a really specific function. for example, our outer layerof epithelial cells, here, they have a protective function

against the outside environment. and, you know, just thinkingof other adult cell types, right, like muscle cellshave a contractile function, and neurons have amessage sending function, and bones have a rigidstructural function. so, all these adult cells are already nice and specialized, they'vegrown up and decided what they wanna do for a living, whereas, stem cells arenot like that at all.

stem cells are unspecialized. but, they still have areally important job, which is to give rise to ourmore specialized cell types, like these cells here, okay? and, actually, in order tobe considered a stem cell, and this goes for theembryonic stem cells we met previously and the somaticstem cells we're meeting now, to be a stem cell, you'd need to possess two main properties.

the ability to self renew,meaning you can divide and divide, and divide, but, at least one of your resultingcells remains a stem cell, it remains undifferentiated, and you'd need to have a high capacity to differentiate intomore specialized cells when the time comes. so, remember, this is also referred to as having some degree of potency.

and there's actually a few different types of stem cells, and someof them can turn into more types of cells than others. some are more potent than others. so, this epithelial stem cell we saw here is actually one of the lesspotent types of stem cell. in other words, thesestem cells can only divide and specialize into more epithelial cells. so, they're our source ofepithelial cells, sure,

but, only epithelial cellsand not any other cell type. so, we call them unipotent,referring to their ability to only create one type of cell. but, lemme show you another example here of a multipotent stem cell. let's look at this guy'sfemur, his thigh bone, which is where our blood cells are made inside bone marrow in our bones. so, you might know thatour red blood cells

have a life span of about four months. so, that means that we needto be constantly replacing our red blood cells orwe'll run out, right? well, in our bone marrow,we have what are called hematopoietic stem cells, which are our blood making stem cells. and these are pretty special, they're multipotent stem cells, which means they can giverise to many types of cells,

but, only ones within a specific family. in this case, blood cells,and not, for example, cells of the nervous systemor the skeletal system. so, our hematopoietic stem cells are always busy churningout new blood cells, red blood cells to carry oxygen for us, and white blood cells to keep our immune system nice and strong. and for a more clinical example,

with blood diseases like leukemia, certain blood cellswill grow uncontrollably within a patient's bone marrow, and it actually crowds out their healthy stem cells, here, from being able to produce enough blood cells. so, as part of treatment,once the leukemia cells are cleared from the bone marrowwith, usually, chemotherapy or radiation, doctors can actually put

more hematopoietic stem cellsback into the bone marrow that then go on to produce normal amounts of blood for the person again. so, this is probably the most common use of stem cells in medicine as of now. and you can actually findthese multipotent stem cells in most tissues and organs. so, for example, we havemultipotent neural stem cells that slowly give rise to neurons

and their supporting cells when necessary. and we have multipotentmesenchymal stem cells in a few different places in the body that give rise to bonecells and cartilage cells, and adipose cells. so, you might be wonderingafter seeing our epithelial and our hematopoietic stem cells dividing, why aren't these cells beingused up as they divide? and that's a really good question.

so, stem cells havetwo mechanisms in place to make sure that theirnumbers are maintained. so, their first trick isthat when they divide, they undergo what's calledobligate asymmetric replication where the stem cell dividesinto one so called mother cell identical to the original stem cell, and one daughter cellthat's differentiated. so, then, the daughtercell can go on to become more specialized while the mother cell

replaces the stem cellthat divided, initially. the other mechanism is calledstochastic differentiation. so, if one stem cellhappens to differentiate into two daughter cells insteadof a mother and a daughter, another stem cell will notice this and makes up for the lossof the original stem cell by undergoing mitosis andproducing two stem cells identical to the original. so, these two mechanisms make sure

their numbers remain nice and strong. so, we've looked at embryonic stem cells and we've looked at somatic stem cells. there's actually one more type called induced pluripotent stemcells, or ips cells. it turns out that youcan actually introduce a few specific genes intoalready specialized somatic cells like muscle cells, andthey'll sort of forget what type of cell they are,and they'll revert back,

they'll be reprogrammedinto a pluripotent stem cell just like an embryonic stem cell. and this is a huge discovery. i mean, the technique isstill being perfected, but, there's a lot ofmedicinal implications, here. for example, ips cellsare basically the core of regenerative medicine,which is a pretty new field of medicine where the goalis to repair damaged tissues in a given person by using stem cells

from their own body. so, with ips cells, each patient can have their own pluripotent stem cell line to theoretically replaceany damaged organs with new ones made out of their own cells. so, not only would apatient get the new organ they might need, but, there also won't be any immune rejection complications since the cells are their own.

so, there's still a ways to go here before this type of medicineis sort of mainstream, but, already, ips cells have helped to create the precursorsto a few different human organs in labs, suchas the heart and the liver. now, before we finish up here, i just wanna answer two questions that might have come up for you. so, one, what triggers ourstem cells to differentiate?

well, it turns out thatin normal situations, right, when the stemcell's just hangin' out, not doin' too much, it actually expresses a few different genes that helps to keep it undifferentiated. so, there are a few proteinsfloating around in the cell that prevents other genesfrom being activated and triggering differentiation. but, when put in certain environments,

this regulation can be overridden, and then, they can go on and differentiate into a more specialized cell. the type of which depends on what specific little chemical signals are hanging around in the stem cell's environment. so, for example, in the bone marrow, there are certain proteinsthat hang around stem cells and induce some to differentiate

into the specific blood cell types. and finally, what's all thisstuff you might have heard, maybe in the news, about cord blood? well, from cord blood,which is blood taken from the placenta and the umbilical cord after the birth of ababy, you can get lots of multipotent stem cells, and sometimes, some other stem cells that have been shown to be pluripotent.

so, this cord blood usedto just be discarded after a baby's birth, but now, there's a lot of interest in keeping it because now we know itcontains all these stem cells.

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stemtech

our expectations for the first treatment,we really were hoping that he would talk, because at the age of 9 flynn couldn't talk.that was our main goal, and main hope was for flynn to be able to talk. my name is frazer rigby, and this is my sonflynn rigby, and we are from australia. cairns, australia. flynn was born at 23 and a half weeks gestation,so extremely premature. we knew there would be big problems because he was born so early,but we hoped that, over time, everything would be fine but - obviously they weren't. flynn'severy stage of his development, was severely delayed, so we knew that we had to do something.whatever we could to help him.

his condition is a result of his cerebellumnot developing, and also those lesions and damage to the brain. as a result of that finemotor skills have been severely affected. speech has been the major problem. he wasable to walk, he was able to reach those milestones, they were delayed, but speech has been onethat up until the age of nine, flynn, he could not talk. the transformation in flynn from before toafter the stem cell treatment has been significant. flynn could not speak and after the treatmenthe could talk. his fine motor skills, in terms of just walking, and riding a bike now, andswimming, and interacting with his peers and

wanting to be a part of society has been asignificant change in flynn. his reading of books, his comprehension has improved andwe are hoping that it will continue to do so. our experience at better being hospital, flynny,has been very good. the staff have been fantastic, the facilities are great, very very similarto our western facilities at home... and it's been very organized and so we've been veryhappy. haven't we flynn? we would definitely recommend stem cell treatmentto people who are looking for some success or potentially some improvements in all typesof conditions in australia. certainly, it has helped flynn, and i'm sure that it couldhelp many people

if they did choose to go down that path. just for us, our journey has been, has beenphenomenal. phenomenal, you know and we've had community support. and the success, weknow that it's all, the majority of that has to do with the stem cells treatment.

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stemenhance

my name is georgiana, i'm living in spain from 10 years, the time when i discovered that i have a severe anemia named thalassemia. fainting frequently , even at work, my condition was permanent fatigue, i felt very bad and my veins where very accented with very thick blood, i saw doctors but i search for natural solutions because we all know that the doctor recommends pills for an illness but pills is having side effects starting to destroy something else inside your body. natural solutions found had no effect . i spent a lot of money on many products that we all know . i do not want to name them because they are very popular and you may spend money unnecessarily . one day i discovered stemtech products , and i decided to try them because i had nothing to lose. from the first day i discovered something very important for me i started to use the toilet daily. this is a big thing for me because of that i had a bad alimentation.

products are available to everyone. between 50 and 100 euros anyone can have it . so they are not expensive ! we all know that no products from other companies do not have effect in half. i can assure you of this because i have tried many and cost much more . i say you with full confidence that these stemtech products are something extraordinary ! fatigue disappears , you can easily solve problems that once they were stressful. you have a lot of energy and your nervous stress because you don't find solutions will disappeared. you're much better from all points of view : stress , fatigue, see things more clearly , think better . i worked and i work a lot. in the past it was hard because of fatigue that i had. i often fainted at work because of my anemia so it was not easy.

now i feel great and am very happy . i am very excited about those products i recommend you those products with all my confidence . if you need you can contact me . i leave you my phone number in spain and those who want to know how to use those products i will explain . tel: 640-674-002

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