[AI] Fwd: Cell jab restores sight in mice

Umesha Economics umesha.eco at gmail.com
Wed Apr 25 17:48:49 PDT 2012

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----- Original Message ----- 
From: "Wahid Raza" <wahid970 at gmail.com>
To: "accessindia" <accessindia at accessindia.org.in>
Sent: Wednesday, 25 April, 2012 10:42 PM
Subject: [AI] Fwd: Cell jab restores sight in mice

> hi all,
> hope all are doing fine
> pasting below article, which get from another list.
> Regards
> Wahid
> ---------- Forwarded message ----------
> Cell jab restores sight in mice
> Published on Wednesday 25 April 2012 16:24
> Experimental cell transplants can improve the sight of visually
> impaired mice, it has been widely reported. The Independent called the
> research behind the news a "major step towards cure for blindness",
> while The Guardian said the work is "the first demonstration that cell
> transplants can restore useful vision".
> During the research, scientists used mice bred to lack working
> light-sensitive "rod cells" in the back of their eyes. These cells
> normally allow us to see in low-light conditions. These visually
> impaired mice were then injected with immature cells extracted from
> the eyes of young mice with normal vision in the hope that this would
> improve their sight. Following treatment, the mice were tested in a
> simple maze featuring visual indicators of the location of the exit.
> Visually impaired mice that were not treated struggled to find the
> exit, while some of those given transplants successfully identified
> the exit 70% of the time. The researchers concluded that treatment
> with these immature rod cells can improve vision, but that
> significantly more research is needed before this treatment would be
> suitable for use in people.
> This early-stage research supports the continued study of immature (or
> 'precursor') rod cell injection as a possible treatment for a specific
> type of blindness. However, it is unknown at this stage whether
> similar results will be achievable in humans. Also, there are many
> different causes of blindness and sight loss. Even if this technique
> eventually reaches humans, there is no indication it would help with
> vision problems that are not related to rod cells.
> Where did the story come from?
> The study was carried out by researchers from University College
> London, Johns Hopkins University School of Medicine and Cornell
> University in the US. It was funded by the Medical Research Council
> UK, the Wellcome Trust, the Royal Society, the British Retinitis
> Pigmentosa Society and The Miller's Trust.
> The study was published in the peer-reviewed scientific journal Nature.
> Generally, the media reported the story accurately, with the BBC, The
> Daily Telegraph, the Daily Mail and The Independent all reporting that
> research in humans is likely to be years away. They also correctly
> emphasised that the mice were not completely blind before their cell
> transplants but, instead, lacked the cells needed to see in low-light
> conditions.
> What kind of research was this?
> This was an animal study that examined the effectiveness of eye cell
> transplantation for restoring vision in sight-impaired mice.
> Within the human eye, two types of light-sensitive cells work together
> to enable vision
>  a.. rod photoreceptors are responsible for vision in low-light
> conditions, or night vision
>  b.. cone photoreceptors allow us to see colours and fine details,
> and to see in bright conditions
> When we look at an object or scene, the lenses of the eye focus light
> from what we are viewing onto the retina, a structure at the back of
> the eye that is lined with rod and cone cells. As these detect light,
> they produce information that is then sent down the optic nerves and
> decoded by the brain.
> The mice used in the study had a genetic mutation that results in a
> lack of functioning rod cells, and these mice serve as a model for
> studying genetic night blindness. Mouse research of this type is
> commonly used to prove that the concept or theory underlying a new
> treatment approach is sound, and that the experimental procedures are
> safe. Once this is established, small-scale human studies can be
> undertaken to establish the effectiveness and safety of the treatment
> in people.
> However, as this was an animal study, at this early stage of research
> we cannot be sure that the results will also hold true in people. In
> this case, it is particularly true as mice see in a slightly different
> way from humans. Research suggests they generally have a low number of
> colour-sensitive cone cells that enable full-colour vision, and
> instead have a higher proportion of rod cells to help them see
> nocturnally.
> What did the research involve?
> The research had two parts. First, researchers examined a group of 29
> mice with the genetic mutation that results in night blindness and
> compared them to nine normal mice with functioning rod cells. The
> researchers then collected "precursor rod photoreceptor cells" from
> another set of normal mice aged four to eight days old with
> functioning rods cells. Precursor rod cells are those that have not
> yet matured into adult cells, although they have already started to
> show some of the properties that adult cells do.
> These extracted precursor cells were then injected into the retinas of
> both the night-blind mice and the normal mice. The researchers then
> compared the two groups of mice in terms of how well the transplanted
> cells integrated into the retina and how well their retinas were
> responding to light.
> In the second part of the study, the researchers examined whether
> transplanting precursor rod receptor cells into mice with night
> blindness resulted in improved vision. To do this they took mice with
> the night blindness genetic mutation and split them into two groups.
> The first group of nine mice received an injection of the precursor
> rod photoreceptor cells, and the second group of 12 mice received
> either a sham injection (an injection with no precursor cells in it)
> or remained untreated. A group of four mice with functioning rods were
> included in this part of the study as well. In low-light conditions,
> the researchers had the mice repeatedly attempt to navigate a Y-shaped
> water maze, which had a platform on one arm from which the mice could
> get out of the water. The arm of the maze containing the platform was
> marked with a specific pattern that mice with normal night vision
> should be able to see, but not mice with night blindness.
> After getting out of the maze the first time, the mice that could see
> the pattern should have been able to recognise that it indicated the
> location of the platform. This would allow them to correctly identify
> and swim down the arm containing the platform in a series of
> subsequent tests. Mice that couldn't see the pattern would just
> randomly pick an arm to swim down each time until they found the
> platform by chance. The researchers compared how many of the mice
> consistently passed the trial by selecting the maze arm with the
> pattern and platform.
> What were the basic results?
> In the first part of the study, the researchers found that up to
> 26,000 new rod cells became integrated into the retinas of the mice
> that had been injected with rod precursor cells. The night-blind mice
> injected with these cells showed similar retinal function to the mice
> with working rod cells.
> In the second part of the study, the researchers found that:
>  a.. Four of the nine night-blind mice who had received the rod
> photoreceptor injection consistently passed the maze, selecting the
> correct arm first for at least 70% of their attempts.
>  b.. All four mice with healthy rods consistently passed the maze,
> choosing the correct arm first in more than 80% of their attempts.
>  c.. None of the 12 night-blind mice receiving no treatment or a sham
> injection consistently passed the maze. They selected the correct arm
> of the maze no more often than they would be expected to do by chance.
> How did the researchers interpret the results?
> The researchers conclude that transplanted rod photoreceptor
> precursors can successfully integrate into the retinas of adult mice
> with non-functioning rod cells, and can improve night vision.
> Conclusion
> The results of this study indicate that transplanting precursor rod
> photoreceptor cells into a retina with non-functioning rods can
> improve night vision in some mice with a very specific type of night
> blindness. For a variety of reasons it is unclear at this point
> whether such a transplant would be effective at restoring night vision
> in people, and it is important to view this as very early stage
> research. When assessing the value of this research the following must
> be considered.
>  a.. As with all animal studies, the results found here may not
> translate into similar effects in humans.
>  b.. The researchers reported that the visual functioning of the mice
> with night blindness was still lower after treatment than in the
> animals with functioning rods, and not all of the treated mice
> performed significantly better than untreated night-blind mice in the
> maze test.
>  c.. The technique will need to be adapted specifically for humans.
> For example, researchers will need to identify an appropriate source
> of similar precursor cells for humans, for example from embryonic stem
> cells or adult stem cells.
>  d.. The type of mouse blindness in this study, in addition to being
> an animal model for night blindness, was the result of a specific
> genetic mutation that resulted in structurally intact but
> non-functioning rod cells. Other types of blindness, for instance,
> those involving another type of photoreceptor, called cones, have not
> been studied here. Indeed, the mice involved in this study had
> functioning cone photoreceptors, which are responsible for colour
> vision and seeing detail in bright light conditions.
>  e.. Blindness can result from various causes, including genetic
> factors, degeneration of parts of the eye, or damage to the eyes,
> optic nerves or areas of the brain responsible for processing visual
> information. This treatment would not be suitable for many eye
> conditions that are not caused by a failure of the rod cells. For
> example, integration of functioning rods into the retina would not be
> a suitable treatment for blindness caused by damage to the optic nerve
> or visual areas of the brain.
> This study showed that, in an animal model, treatment with precursor
> rod photoreceptors can lead to improved vision in mice with night
> blindness. As correctly pointed out by many newspapers, this research
> is still years away from potentially being used in people. As the
> study's authors say, much more research is needed before the results
> of this study can be used in a clinical setting.
> Analysis by Bazian
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