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Stem cells have two key characteristics. They are able to self-renew and they can differentiate into mature cells of different lineages. These two properties allow stem cells to repair and regenerate tissues and organs. Stem cells also form the corner-stone of tissue engineering. The underlying biological mechanisms that regulate stem cell function and self-renewal are fairly complex and our knowledge of remains very limited.The field of stem cell research has generated a lot of enthusiasm, but this enthusiasm can at times skew the interpretation of the actual scientific findings. I believe that the hope of being able to regenerate or rejuvenate tissues taps into the old human quest for immortality. This may be the reason why I often come across reports and discussions suggesting that stem cell therapies have a miracle-like quality and will soon be able to cure most diseases. While the ground-breaking discoveries in stem cell biology are indeed fascinating, it is also important to have a realistic view of stem cell therapies and realize that much of stem cell biology is still in its infancy. Premature attempts to use stem cells for clinical therapies are probably not going to succeed. This blog will focus on novel developments in stem cell research, regenerative biology and medicine as well as the topic of aging. The ethical and political issues that revolve around stem cell research will also be discussed. I am also interested in broader questions related to the process of scientific discovery, creativity and scientific communication, which will be addressed in some of the posts.
The hypothalamus is located at the base of the brain and in adult humans, it has a volume of only 4cm3, less than half a percent of the total adult human brain volume. Despite its small size, the hypothalamus is one of the most important control centers in our brain because it functions as the major interface between two regulatory systems in our body: The nervous system and the endocrine (hormonal) system. It consists of many subunits (nuclei) which continuously sense inputs and then respond to........ Read more »
Zhang G, Li J, Purkayastha S, Tang Y, Zhang H, Yin Y, Li B, Liu G, & Cai D. (2013) Hypothalamic programming of systemic ageing involving IKK-β, NF-κB and GnRH. Nature, 497(7448), 211-216. PMID: 23636330
Medieval alchemists devoted their lives to the pursuit of the infamous Philosopher's Stone, an elusive substance that was thought to convert base metals into valuable gold. Needless to say, nobody ever discovered the Philosopher’s Stone. Well, perhaps some alchemist did get lucky but was wise enough to keep the discovery secret. Instead of publishing the discovery and receiving the Nobel Prize for Alchemy, the lucky alchemist probably just walked around in junkyards, surreptitiously c........ Read more »
Nam, Y., Song, K., Luo, X., Daniel, E., Lambeth, K., West, K., Hill, J., DiMaio, J., Baker, L., Bassel-Duby, R.... (2013) Reprogramming of human fibroblasts toward a cardiac fate. Proceedings of the National Academy of Sciences, 110(14), 5588-5593. DOI: 10.1073/pnas.1301019110
For over a decade, cardiologists have been conducting trials in patients using cells extracted from the bone marrow and infusing them into the blood vessels of the heart in patients who have suffered a heart attack. This type of a procedure is not without risks.... Read more »
Surder, D., Manka, R., Lo Cicero, V., Moccetti, T., Rufibach, K., Soncin, S., Turchetto, L., Radrizzani, M., Astori, G., Schwitter, J.... (2013) Intracoronary Injection of Bone Marrow Derived Mononuclear Cells, Early or Late after Acute Myocardial Infarction: Effects on Global Left Ventricular Function Four months results of the SWISS-AMI trial. Circulation. DOI: 10.1161/CIRCULATIONAHA.112.001035
Rehman, J. (2013) Bone Marrow Tinctures for Cardiovascular Disease: Lost in Translation. Circulation. DOI: 10.1161/CIRCULATIONAHA.113.002775
The ENCODE (Encyclopedia Of DNA Elements) project received quite a bit of attention when its results were publicized last year. This project involved a very large consortium of scientists with the goal to identify all the functional elements in the human genome. In September 2012, 30 papers were published in a coordinated release and their extraordinary claim was that roughly 80% of the human genome was "functional". This was in direct contrast to the prevailing view among molecular bi........ Read more »
Graur D, Zheng Y, Price N, Azevedo RB, Zufall RA, & Elhaik E. (2013) On the immortality of television sets: "function" in the human genome according to the evolution-free gospel of ENCODE. Genome biology and evolution. PMID: 23431001
Neurogenic bladder is a disorder which occurs in spinal cord diseases such as spina bifida and is characterized by an inability of the nervous system to properly control the urinary bladder and the muscle tissue contained in the bladder wall. This can lead to spasms and a build-up of pressure in the bladder, often resulting in urinary incontinence. Children with spina bifida and neurogenic bladder may feel urges to urinate after drinking comparatively small amounts of liquid and they can also in........ Read more »
Franck, D., Gil, E., Adam, R., Kaplan, D., Chung, Y., Estrada, C., & Mauney, J. (2013) Evaluation of Silk Biomaterials in Combination with Extracellular Matrix Coatings for Bladder Tissue Engineering with Primary and Pluripotent Cells. PLoS ONE, 8(2). DOI: 10.1371/journal.pone.0056237
To celebrate Valentine's Day (as a geeky scientist), I decided to search the "Web of Science" database for published articles with the phrase "Valentine's Day" in the title. The article that had the most citations was "Market-resistance and Valentine's Day events" published in the Journal of Business Research in 2009, by the authors Angeline Close and George Zinkhan. I had never heard of the journal before, but the title sounded very interesting so I ........ Read more »
Our ability to test for the presence of genetic mutations has become extremely cost-efficient and private companies, such as 23andMe now offer genetic testing for consumers who want to find out about their predisposition for genetic diseases. The results of such tests are sent directly to the consumers, without the involvement of genetic counselors or other healthcare providers. This has lead to a growing concern about how people will respond to finding out that they are carriers of mutations th........ Read more »
Francke, U., Dijamco, C., Kiefer, A., Eriksson, N., Moiseff, B., Tung, J., & Mountain, J. (2013) Dealing with the unexpected: consumer responses to direct-access BRCA mutation testing. PeerJ. DOI: 10.7717/peerj.8
When we hear the expression "stem cells", we tend to think of cells from animals or patients that are used to treat for diseases or promote regeneration. However, stem cells are also present in plants. The growing tips of plants are called meristems and they are reservoirs of plant stem cells. A meristem is formed at the base of each leaf and can remain dormant as a small bud or be activated and give rise to a whole new branch. Gardeners know that pruning leaves can activate the buds and help tr........ Read more »
Shinohara, N., Taylor, C., & Leyser, O. (2013) Strigolactone Can Promote or Inhibit Shoot Branching by Triggering Rapid Depletion of the Auxin Efflux Protein PIN1 from the Plasma Membrane. PLoS Biology, 11(1). DOI: 10.1371/journal.pbio.1001474
The recent paper "On-demand optogenetic control of spontaneous seizures in temporal lobe epilepsy" by Esther Krook-Magnuson and colleagues in Nature Communications (published online on January 22, 2013) applies the optogenetic approach to treat seizures in mice. The researchers used mice that had been genetically modified to express the inhibitory light sensitive protein halorhodopsin (normally only found in single cell organisms but not in mammals) in neurons. They placed an optical f........ Read more »
Krook-Magnuson, E., Armstrong, C., Oijala, M., & Soltesz, I. (2013) On-demand optogenetic control of spontaneous seizures in temporal lobe epilepsy. Nature Communications, 1376. DOI: 10.1038/ncomms2376
In summary, the paper by Wolff and colleagues does not really answer the question of whether cannabis-related stroke is myth or reality. The small sample size, the observational nature of the data, the lack of follow up imaging on all the patients and the lack of controlling for confounding risk factors such as tobacco (which has a very strong association with stroke) make it difficult to draw definitive conclusions. All we can say is that Wolff and colleagues have presented an intriguing hypoth........ Read more »
One of the most important take home messages of this work is that we need get rid of the common “oxidants are bad guys and antioxidants are good guys” myth. Oxidants can be harmful in some context, but they can also serve as important regenerative signals. Indiscriminate use of antioxidants can actually impair these important endogenous signals. Instead of consuming large quantities of non-specific antioxidants, we need to use antioxidants in a very targeted, context-specific and per........ Read more »
Love, N., Chen, Y., Ishibashi, S., Kritsiligkou, P., Lea, R., Koh, Y., Gallop, J., Dorey, K., & Amaya, E. (2013) Amputation-induced reactive oxygen species are required for successful Xenopus tadpole tail regeneration. Nature Cell Biology. DOI: 10.1038/ncb2659
On a practical level, this study suggests that it may be important to derive multiple iPSC clones from a subject's or patient's skin cells, if one wants to use the iPSCs for disease modeling. This will help control for the genetic diversity that exists among the skin cells. However, a much more profound implication of this work is that we have to think about between-cell diversity within a single organ.... Read more »
Abyzov A, Mariani J, Palejev D, Zhang Y, Haney MS, Tomasini L, Ferrandino AF, Rosenberg Belmaker LA, Szekely A, Wilson M.... (2012) Somatic copy number mosaicism in human skin revealed by induced pluripotent stem cells. Nature, 492(7429), 438-42. PMID: 23160490
The researchers treated mice with Viagra (sildenafil), a drug that is normally used for erectile dysfunction. They found that only seven days of Viagra treatment increased the levels of the brown fat protein UCP-1 and that the white fat began showing the presence of "beige" (not quite white and not fully brown) fat. The choice of Viagra was not quite arbitrary, because they also showed that cultured fat cells contain cGMP-dependent protein kinase I (PKGI), which is part of the signalin........ Read more »
Mitschke, M., Hoffmann, L., Gnad, T., Scholz, D., Kruithoff, K., Mayer, P., Haas, B., Sassmann, A., Pfeifer, A., & Kilic, A. (2013) Increased cGMP promotes healthy expansion and browning of white adipose tissue. The FASEB Journal. DOI: 10.1096/fj.12-221580
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