Research Roundup: Possible cure for genetic infertility, zebrafish as a model organism for cancer and more!

Welcome to this week’s Research Roundup. These Friday posts aim to inform our readers about the many stories that relate to animal research each week. Do you have an animal research story we should include in next week’s Research Roundup? You can send it to us via our Facebook page or through the contact form on the website.

  • Can a new technique for the creation of artificial sperm lead to a cure for genetic infertility? Sex is determined by the X and Y chromosomes. Females have two X chromosomes (XX) and males have one X and one Y (XY). About 1 in 500 males are born with an extra Y chromosome, Klinefelter’s syndrome (XXY), while roughly 1 in 1,000 males are born with double Y chromosomes, or Jacob’s syndrome (XYY) — two different forms of trisomy, which lead to infertility. Mimicking these syndromes in mice, in a jointly funded research project by the EU and Japan, these researchers took pieces of ear tissue, cultured them and then used fibroblasts from that culture to create stem cells. Curiously, in some of these stem cells, the extra sex chromosome was lost – yielding “normal” cells. They then induced these “normal” stem cells to differentiate into sperm cells and injected them into the testes of these infertile mice where the matured into healthy sperm cells — although some of these mice developed tumors. These healthy sperm cells were then collected and through assisted reproduction, created healthy fertile offspring. In a preliminary experiment, they also found that stem cells derived from men with Klinefelter’s syndrome also lost their extra sex chromosome. This research was published in the journal Science.

Image: Research schematic. Credit: Takayuki Hirota.

  • Adult neurogenesis found in the brain area that links memory to emotion. Neurogenesis (the formation of new neurons by cell division, and their incorporation to existing circuits) is a powerful mechanism of brain plasticity. Previous studies have indicated that neurogenesis only occurs in a few parts of the adult brain. This week, a team from the University of Queensland has reported that neurogenesis also occurs in the adult mouse amygdala, a structure located deep in the temporal lobe which is linked to the establishment of emotional memories. The amygdala plays a key role in controlling the way people react to certain stimuli or an emotional event, particularly if these are viewed as potentially threatening or dangerous. “Finding ways of stimulating the production of new brain cells in the amygdala could give us new avenues for treating disorders of fear processing, which include anxiety, PTSD and depression”, said author Dr. Dhanisha Jhaveri. This study was published in the journal Molecular Psychiatry.
  • Plausibility of humanized mice questioned for stem cell transplant research. Humanized mice are engineered to have human immune systems, rather than a typical mouse immune system, and are frequently used across research. Some studies using humanized mice investigate the immune response to transplanting pancreatic islet cells for diabetes or skin grafts for burn victims. Recently, however, researchers at Stanford are suggesting that these mice are unsuitable for investigating questions related to stem cell transplantation and immune function/response. Their suggestion comes from several experiments where they transplanted genetically mismatched human stem cells in either humanized mice or actual humans. They found that humanized mice often accepted these transplants, while humans often rejected these transplants. Therefore, humanized mice might not be the best animal model for understanding relationships between stem cell transplantation and immune response. This is a great example of scientists working together to assure that animals’ lives are not wasted and the ability of science to refine its methodology over time. This study was published in Cell Reports.
knockout mice, animal research, animal rights

Researchers found that humanized mice often accepted stem cell transplants, while humans often rejected these transplants. (Mouse image from NIH)

  • Artificial womb used to successfully grow premature lamb for the second time. A collaborative of researchers from the Women and Infants Research Foundation, the University of Western Australia, and Tohoku University Hospital, Japan have successfully brought a preterm lamb to full term in an artificial womb. This study is similar to the results reported earlier this year by researchers at the Children’s Hospital of Philadelphia. Here, the lamb, analogous to a human fetus aged around 23 weeks old, was placed into a clear plastic bag filled with special amniotic fluid and an artificial placenta. Associate Professor Matt Kemp, led the development of this second artificial womb says,. “By providing an alternative means of gas exchange for the fetus, we hoped to spare the extremely preterm cardiopulmonary system from ventilation-derived injury, and save the lives of those babies whose lungs are too immature to breathe properly.” This advancement provides hope for families of babies who are born extremely premature in the possibility of increased survival rates.This study was published in The American Journal of Obstetrics and Gynecology.

  • Zebrafish larvae might be used to help doctors decide the best course of treatment for each cancer patient. A group of researchers from the Champalimaud Centre for the Unknown published this week, in the journal PNAS, preliminary data showing that colorectal cancer cells taken from patients can be injected in zebrafish larvae where they develop and show all the hallmarks of tumors. The researchers then treated these zebrafish avatars with different chemotherapy cocktails. In 4 out of 5 tested samples, the tumors grown in zebrafish responded similarly to how donor patients had responded to the chemotherapy they had gone through. This proof-of-concept study shows that there is promise in using zebrafish to predict, in just 2 to 3 days, how a patient will respond to each available treatment, and guide its chemotherapy regime accordingly. This study is now in a 2nd phase that includes hundreds of patients from the Champalimaud Centre for the Unknown and the Amadora-Sintra Hospital.

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