AP Biology class blog for discussing current research in Biology

Tag: stem cells

Dolly’s Legacy and the Healthy State of Sheep Clones

Over the past two decades, there has been much discussion around Dolly in the scientific community.  No, not Dolly Parton (although her name served as an inspiration), but Dolly the cloned sheep.  In 1996, researchers at the Roslin Institute, an animal sciences research center at the University of Edinburgh, made history by cloning the first mammal from an adult somatic cell via nuclear transfer.  The cell utilized for the cloning was from a mammary gland, and Dolly’s successful birth and 6 year longevity signified that cells other than gametes and germ cells could recreate an organism.  However, scientists and laymen alike have expressed concern regarding Dolly’s short lifespan in respective to the overage sheep’s of 10-12 years.  Does this mean clones are unhealthier versions of their “natural” predecessors?

dolly_face_closeupPhoto of Dolly’s taxidermied remains by Toni Barros, source

According to research conducted by Kevin Sinclair of the University of Nottingham, the answer is no.  Monitoring four sheep derived from the same mammary gland cells as Dolly in addition to nine cloned sheep of other breeds, Sinclair has dug up no evidence to suggest that the clones are less healthy than sheep born of natural processes.  In fact, all 13 of the sheep are now older than nine (equivalent to 70 or 80 years in the lifespan of a human) and are as healthy as their non-cloned counterparts according to tests scanning their bones, blood glucose levels, and blood pressure.

And so the question is posed, why did Dolly die young?  Scientists who interacted with Dolly claim that her life was taken by a contagious illness that ravaged the flock- not some defect as a result of her being a clone.  To address Dolly’s severe amounts of arthritis at the time of her death, geneticist Helen Sang from the Roslin Institute points to her indoor captivity and the excessive amounts of treats she was given.

While cloning might not be as efficient as traditional modes of breeding, this study exhibits that cloned animals which survive gestation and are relatively healthy during their infancy have the same chances of thriving and living to expected longevity as any other animal of the breed.  Additionally, cloning allows scientists to generate embryonic stem cells for further scientific research and to produce “high-value livestock”.  These advantages begin to show the importance of clowning and how beneficial it can become if it is accepted as an integral part of scientific studies. What animals are next to be cloned?  What impacts would cloning humans have on our society?

All Organs are Sexual!

Well, in the sense that female non-sexual organs and male non-sexual organs aren’t the same, as they’ve been commonly considered to be. According to a team at the MRC Clinical Sciences Centre (CSC), at Imperial College London, the stem cells that make up your organs do have a sexual identity attached to them, and thus behave differently than their sexual counterparts. In this study, a female fruit fly’s gut was observed to have enlarged after mating, likely due to the increased nutritional intake to rear healthy offspring. The reason this isn’t done all the time is that this makes it more likely for tumors to develop in the gut, so this is only done when the sake of their progeny is at stake.

(This fruit fly may be female, but her intestines were made to identify as male. There’s potentially some conflicted gender identity.)

What’s interesting is that when the female fruit fly was given male gut stem cells, the gut no longer enlarged after mating, and retained the smaller gut size of males. It turns out that the sex organs are not the only organs that have a sexual identity. At least, in fruit flies. No tests have been done on human organs yet, although it is believed that the principle will hold true, albeit in potentially different ways.

(Artist rendition of stem cells)

Medically this is significant since it may lead to explanations or understandings of how and why male and female patients may need different medical treatments since their organs function somewhat differently. Furthermore, it continues to advance our understanding of how males and females are different based on the nuances of the physical workings of their body. Overall, it’s very confusing when you apply this to gender theory.

But humans have had a poor understanding of their own bodies and inner workings for thousands of years. Is it possible that this is on the path to a deeper understanding of our physiology as a gendered species, or that these differences are conditional and minute, as I so far believe?



Human skin cells reprogrammed directly into brain cells



Original article:

Some key words:

Neurodegenerative diseases: Disease such as Alzheimer’s, Parkinson’s and Huntington’s disease that undergo a neurodegenerative process, specific neurons are targeted for degeneration.

Spiny brain cell: The desired end brain cell in this study, and a brain cell affected by Huntington’s disease


In a study by the researchers at Washington University School of Medicine in Saint Louis, they demonstrate a way for human skin cells to be specifically converted to a type of brain cell. This study can help in the rehabilitation of people with Huntington’s disease by turning skin cells in to brain cells that are lost through this neurodegenerative disease. This is all accomplished without passing through the stem cell phase preventing other cell types forming.

This research involved adult skin cells that Yoo, the senior author, and his colleagues reprogrammed by using two microRNAs: miR-9, and miR-124. These micro RNAs open up the otherwise tightly packaged and inactive sections of the gene critical to the formation of brain cells. While the micro RNAs open up genes used for the creation and functionality of neurons, transcription factors taken from a part of the brain where medium spiny neurons are common directs the newly formed brain cells to a specific subunit of brain cells. The researchers then observed that the newly formed brain cells behave and function in a similar way to the native medium spiny neurons in mice, allowing this study to proceed in to further stages of experimentation, and hopefully result in a treatment practical for human use.

This study is very critical in the advancement of the treatment for neurodegenerative disease such as Huntington’s disease. Using different transcription factors from parts of the brain, alternate types of brain cells can be created to replace cells lost from neurodegenerative effects. This form of treatment will also prevent rejection of the transplant because the skin cells can be taken from the patient’s own body. This is a breakthrough in our pursuit of cures for these lethal neurodegenerative diseases.

Dying Brain cells signal new brain cells to grow in songbird



Original article:

In a recent paper written by leading author Tracy Larson and co-authors Nivretta Thatra and Brian Lee, they discovered a brain pathway that replaces brain cells lost naturally. This study could further the progress of using replacement cells for the neurons lost during aging, Alzheimer’s Disease, and other natural causes.

These scientists used songbirds, specifically Gambel’s white-crowned sparrows, as a model and observed that the area of their brain that controls song increases during breeding season, and decreases during other times in the year. After breeding season the cells in the area of the bird’s brain that controls songs undergoes programmed cell death. What is noteworthy about these dying cells is that they are also releasing a signal that reaches certain stem cells in the brain that will eventually redevelop the singing part of the brain by the time the next breeding season arrives. This process of developing new neurons from stem cells called neurogenesis normally occurs in the form of “regenerative” neurogenesis post brain trauma in mammals; however, it also occurs in the hippocampus in small amounts.

These songbirds could provide insight on how the human brain can perform natural neurogenesis and help replace neurons lost because of aging and neurodegenerative diseases. These finding may pave the way to alternative treatment for repairing human brains using neurogenesis and replacement cells.

Spinal Neurogenesis

An astrocyte cell grown in tissue culture as viewed by Gerry Shaw

Normally, when spinal neurons are lost during life due to disease or injury, they are lost for good, however, thanks to a recent study done by  Zhida Su and his colleagues at the University of Texas Southwestern Medical Center that may no longer be the case. The team took astrocytes—star-shaped support cells in the nervous system— from the spines of living mice and converted them into neurons. This research was based of the previous works of  Marius Wernig from the Stanford University School of Medicine, who first converted rat skin cells into stem cell like cells and then into neurons, Benedikt Berninger from Ludwig Maximillians University Munich, who took certain brain cells and turned them into neurons, and Olof Torper from Lund University, who transformed astroytes from the brains of mice into neurons. Su and his team were drawn to spinal astrocytes because they form scar tissue after spinal cord injuries.

Su and his team accomplished this transformation by injecting a series of viruses into the mice, one of which, SOX2, managed to convert the spinal astrocytes into neuroblasts, both in culture and in living mice who had suffered spinal injuries. Some of these neuroblasts then went on to form functioning neurons and with the addition of valproic acid the number of cells which matured doubled and actually interacted with existing motor neurons.  Although this process is slow and can take up to four weeks, it is incredibly promising and it is even suggested that, “For each reprogrammed [cell], perhaps more than one new neuron could be generated,” meaning that each neuroblast could divide and create multiple neurons. Although this research is extremely promising, only 3-6% of astrocytes effected become neuroblasts which has been in no way enough to study the effects on the health of the mice. However, this research is very young and could lead to major achievments in neurogenesis in the future and the “curing” of paralysis and other conditions that result from the destruction of neurons.

Mouse Stem Cells Become “Grandparents”

Copyright: Anne Burgess

Recently, researchers at Kyoto University in Japan were able to induce stem cells of rats to become viable eggs, which were then implanted in surrogate mothers. The resultant offspring were fertile, anatomically intact rats that were bred for additional generations, their ancestor being only a cell in a petri dish. This discovery has excited scientists the world over because it marks the first step towards making eggs for infertile humans or gays and lesbians.


The scientists at Kyoto began by taking female embryonic cells and “induced pluripotent stem cells”, and then inducing them to become an early form of eggs. Induced pluripotent stem cells (iPSCs) are adult cells that have been reprogrammed to express certain genes that make them effectively embryonic cells. There is some debate as to whether iPSCs differ from embryonic stem cells taken from harvested embryos, but in this instance they acted identically to the conventional stem cells.


The immature eggs, called “primordial germ-like cells” or PGCLCs, were then surrounded by “female gonadal somatic cells” (cells usually found in an ovary) to create a reconstituted ovary. These constructed ovaries were implanted into surrogate mothers, where the PGCLCs matured into “germinal vesicle-stage oocytes” or early embryos formed during the primary oocyte stage of oogenesis (egg formation), which occurs before birth. The mice that had been implanted with these constructed ovaries eventually gave birth to fertile offspring, which were followed by a few additional generations.


Though scientists have called this discovery a major step forward in reproductive biology, the lead scientist on the Kyoto team, Dr. Hayashi, cautioned: “it is impossible to immediately adapt this system to human stem cells” for a number of reasons scientific and moral. Creating egg cells from stem cells in humans could allow menopausal women to conceive, which brings its own set of moral quandaries as well. Ronald Green, a bioethicist at Dartmouth University, commented on NPR that one had to consider “the commercial possibilities of people selling to infertile people babies produced from George Clooney or Jennifer Aniston.” Evidently, the possibility that egg manufacture might one day be possible has sparked heated debate, but one must remember that it may only be speculation.

Gerbils Can You Hear Me?

80 to 90 percent of people suffer from inherited deafness. In a study, scientists have reversed deafness in gerbils. This is a huge step in gene therapy research this month making the possibility of using gene therapy as a cure for deftness one step closer. Genetic therapy is the use of genetic material such as DNA to manipulate a cell and is generally used to treat inherited diseases; in this case scientists used human embryonic stem cells. The gerbils in the study were born deaf. This type of deafness is a birth defect caused by damage to hair cells in the inner ear. These inner ear hair along with auditory neurons which translate sound vibrations from the inner-ear cells to electrical signals are how you can hear. Scientists specifically worked on gerbils whose deafness was caused by a mutation in a gene coding for a protein called vesicular glumamate transporter-3. Even minor alterations to a protein’s primary structure ,such as the movement of a double bond, will cause major defects in the tertiary structure and the function of the protein. The mutated protein in this study vesicular glutamate transporter-3 controls the consumption of glutamate (neurotransmitter) into synaptic vesicles, which join two nerve cells, of the neural cells. This is clearly groundbreaking news this month and has proved the various use of stem cells. How do you feel about the use of embryonic stem cell research? Feel free to comment!!



New Stem Cell Discovered in Brain

Credit Isaac Mao,

At Lund University, researchers have discovered a brand new type of stem cell in the adult human brain, which is thought to be responsible for the regeneration of muscle, bone, cartilage, and adipose tissue.

Stem cells are known for their ability to proliferate into several different cell types, providing a plethora of research opportunities for medical researchers.  These specific stem cells, found near small blood vessels in the brain through the analysis of brain tissue from biopsies, have also been identified in other locations of the body.  In other organs, the stem cell appears to have a similar structure, and is responsible for repair and wound healing, leading scientists to suggest that the curative properties may also apply to the brain.

The next step is to better understand this new type of stem cell, and to learn how to better control and enhance its self-healing properties.  “Our findings show that the cell capacity is much larger than we originally thought, and that these cells are very versatile,” said Gesine Paul-Visse, Ph.D., Associate Professor of Neuroscience at Lund University.

With a more thorough understanding of how this stem cell operates, researchers hope to use it to better treat neurodegenerative diseases and stroke.

As Paul-Visse puts it, “Ultimately the goal is to strengthen these mechanisms and develop new treatments that can repair the diseased brain.”

For more information, read the article “New stem cell found in the brain”

Or look for the original study published in the journal PLos ONE.

So, what do you think?  Will this new stem cell found in the brain make an important impact in neurobiological research?

Forever Young

Photo Credit: Flickr user flatworldsedge

How would you feel if you discovered that your doctors may have found a real fountain of youth?  Well thanks to researchers at the University of Pittsburgh that could someday be a reality.

Dr. Laura Niedernhofer and her fellow researchers have discovered a way to slow down aging, for mice at least.  To conduct their experiment the researchers bred a line of mice with progeria, a disease found in chickens that rapidly increases the aging process.  Normally once a mouse contracts this disease they have only a few days left to live.  After the addition of stem cells as well as some progenitor cells (a similar type of cell) the mice survived up to 66 days.

Now don’t worry its not only some rare poultry disease that this study shows help for.  Mice with mild cases of progeria showed geriatric symptoms similar to those that older humans show, weak leg muscles, walking hunched over and trembling and saw a dramatic improvement.  In fact 75% of the symptoms the mice were experiencing were relieved with only two injections of the stem cell mix given over a period of a few weeks.  Imagine if 75% of an aging human’s symptoms could find relief!

These mice also appear to be showing evidence that the new stem cells didn’t replace their aging stem cells but rejuvenated them as they saw improvement in the brain’s of these mice although the stem cell mix was injected into each mouse’s stomach.  It’s too soon to tell if this stem cell therapy will be able to help humans, but if it did we may have found a real fountain of youth.

Controversial Cure

Photo Credit: Flickr User Paolo Camera

It’s no secret that stem cells

are incredibly controversial.  However, a new study is giving hope that they may be the new cure to the horrible and often fatal disease laminitis

,which is found in horses.  Laminitis is a vascular disease in which areas of ischemia or hemostasis occur with in lamina in a horse.  The lamina are found in the hoof of a horse and are responsible for holding the coffin bone in  place.  In severe cases of laminitis the coffin bone can begin to rotate, and if it becomes fully rotated the bone will come through the hoof if the laminitis is not stopped.  When this occurs the only option is euthanasia for the horse.  Even in horses who survive laminitis this disease can be career ending and will often leave horses only able to live out their lives in a field instead of as a riding horse.  Laminitis was the cause of death for the great horse Secretariat.

This new study

regarding stem cells and laminitis is being conducted by Scott Morrison DVM of Rood and Riddle Equine Hospital, this hospital is located in Lexington Kentucky and is often regarded as being one of the best in the country.  According to Dr.Morrison with tradition methods of treating laminitis he had an 18% success rate treating chronic uncompensated laminitis (this means that there was a loose coffin bone), an 88% success rate treating severe coffin bone rotation and sole penetration and a 44% success rate treating severe coffin bone diseases (bone loss).  In all of the three types of laminitis listed above success refers to a horse returning to pasture soundness, not necessarily being sound to be ridden again.  Dr.Morrison began using allogenic stem cells (harvested from umbilical chord blood) in common laminitis cases 14 months ago and has used it in 31 cases so far finding that he had a 65% (13/20) success rate treating chronic uncompensated laminitis, a 100% (3/3) success rate treating severe rotation cases and a 37.5% (3/8) success rate treating severe coffin bone diseases.  Although the last number is slightly down from traditional methods the other two numbers have been drastically increased showing that stem cells may be the way to go for treating laminitis.  This study is still pretty new and long term effects and success are still unknown but thus far the numbers seem to speak for themselves which leaves the question, despite the controversy over stem cells if they can save these horses lives are they worth using?

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