Cell Biology: Calcium 'Accelerator' Keeps Cell Power Supply GoingScience Daily (press release)The results, appearing November 25, 2012 in an advance online issue of the journal Nature Cell Biology, may also point to new treatment opportunities.
New Promega Assay Improves Cell Culture Cytotoxicity ResultsMidland Daily NewsThe CellTox™ Green Cytotoxicity Assay uses an asymmetric cyanine dye as a fluorescent marker that is impermeable to live cells but strongly binds DNA from dead cells,...
American scientists have developed a hybrid printer that prints cartilage, which could one day be implanted into injured patients to help re-grow cartilage in areas such as the joints. The 3D tissue printer, featured in a study published in the journal Biofabrication by the Institute of Physics, is a mix of a traditional ink jet printer and an electrospinning machine.
In this study, done by scientists at Wake Forest University in North Carolina, the hybrid system produced cartilage with better mechanical stability than those created by an ink jet printer. “This is a proof of concept study and illustrates that a combination of materials and fabrication methods generates durable implantable constructs,” said Dr. James Yoo, a professor at the Wake Forest Institute for Regenerative Medicine, and an author on the study.
Other methods of making cartilage, such as robotic systems, are also being developed to improve implantable tissue. Key to the success of the hybrid printer is the electrospinning machine, which can generate very fine fibres from a polymer solution. The polymers can be easily controlled and made porous, which is important in getting real cartilage cells to integrate into the surrounding tissue.
Researchers built cartilage by combining electrospun polymer with cartilage cells from a rabbit’s ear that were deposited using the traditional ink jet printer. The cartilage was tested on mice and after eight weeks it had developed the structures and properties of real cartilage, demonstrating its potential use in humans.
In future, researchers say clinicians could develop cartilage specific to the needs of patients. For instance, an MRI scan of the body part, such as the knee, would provide a sort of blueprint and then matching cartilage could be created.
They’re soft, biocompatible, about 7 millimeters long – and, incredibly, able to walk by themselves. Miniature “bio-bots” developed at the University of Illinois are making tracks in synthetic biology.
Mycoplasma is a common cause of contamination in cell culture. Because of its small size and lack of a cell wall, a Mycoplasma organism can pass through filters used in sterilization. This interesting article by Martha Folmsbee and others at Pall Life Sciences discusses some of the challenges involved in using filters, for example, when sterilizing broths or culture media.
Folmsbee has published on this topic if you would like to see more:
And don't forget - other methods of sterilization such as autoclaving are very effective and should be used if possible. If you must use a filter (for example if your material is heat-sensitive and so cannot be autoclaved), use a small size such as 0.1 um, consider filtering twice, and change your filter frequently.
Hybridomas - hybrid cell lines used to generate monoclonal antibodies - are a mainstay of antibody production. Hybridomas are made by fusing a B-cell which produces that antibody with a myeloma cell line that fails to produce antibodies but grows well in culture. This post from The Cell Culture Dish blog gives a brief history of hybridoma cell culture and some quick links to recent improvements in hybridoma cell culture.
Promega Launches Novel ADCC Reporter Bioassay for BiologicsMidland Daily NewsPromega Corporation announces the introduction of a novel bioluminescent assay for the quantification of Fc effector function of antibody-based molecules in the...
There's no doubt that when it comes to natural disasters, liquid nitrogen storage of precious samples is your best option. Provided there is sufficient liquid nitrogen, or you can access the area to add more, you can keep your samples going until the power comes back on again.
The link here offers a quick look at DMSO, asking the basic question: is this the best cryoprotectant now available?
There are some excellent reviews of cryopreservation available - also consider looking at a good cell culture textbook for more information. For one recent review see:
Mycoplasma is a common cell culture contaminant that can be hard to detect, and harder to treat. Most cell banks recommend that you discard a Mycoplasma-contaminated culture rather than treat it, but you may be handling something very precious where that is just not possible. So if you must treat, what is the best way to proceed?
This research article from the Leibniz Institute DSMZ (German Collection of Microorganisms and Cell Cultures) looks at how well Mycoplasma treatment works in practice, focusing on Plasmocin, a relatively new agent. The article also includes PCR primers for detecting many of the different Mycoplama species found in culture.
For an excellent review of Mycoplasma contamination by the same authors, see:
Want an example of why it is important to test your cell lines for cross-contamination? Read on.
Over the last few years, the stem cell field has reported several cases of "spontaneous transformation", where cells continue to multiply in culture without any external attempts to make them do so. Usually normal (non-malignant) cells will grow in culture for a finite period of time, and then cell division no longer occurs - the cell has mechanisms that limit cell division and stop the cell from becoming malignant. Scientists can trigger the process of transformation by introducing genes into a cell culture to bypass the control mechanisms.
Spontaneous transformation without any external triggers is a rare event. So if it occurs in stem cells, it would have tremendous implications. For example, stem cells used in therapy could undergo transformation inside the patient and cause cancer.
But are these reports real? Spontaneous transformation was documented for many cell lines in the 1960s and 1970s - and almost all of those cell lines were later found to be cross-contaminated. Is this History repeating itself?
One report of "spontaneous transformation" was published in 2011. A culture of neural stem cells continued to divide without any external manipulation, resulting in the T1 cell line. In accordance with the new push for authenticating cell lines, the authors included an STR profile for the T1 cell line and another from an earlier culture, which they had stored before the cell line was established. Their original article can be found at: http://www.biolsci.org/v07p0892.htm
You can see from their paper that the STR profiles for the cell line and the earlier culture are very different. The authors at the time did not realize the full significance of their result - the difference was put down to "genomic instability" in culture.
But if you are familiar with interpreting STR profiles, you know that two very different STR profiles cannot come from the same individual. Yes, a small amount of genetic drift can happen in culture - but not this much! And when you compare their T1 STR profile to the online databases published by the cell banks, you see a disappointing (but not surprising) result. Anja Torsvik has made the comparison and documented the contaminant in a commentary now published in the same journal: http://www.biolsci.org/v08p1051.htm
Yes, History repeats itself. T1 has been cross-contaminated by the HeLa cell line.