Monday, April 12, 2010

Mr Microbiology's very informative piece on Dr Rivolta's work

I got to correspond with a very knowledgeable Microbiologist who hails from NZ.

This is his take on Dr Rivolta's work which produced a 25dB improvement from 6 animal models using stem cells.

"It is very good to see this news and its now proof of conciept that stem cells can be used to intergrate into the cochlear inner ear and become functional.A barrier for this type of therapy was considering that the original cells hensen , pillar , dieter , support and remaining sensory hair cells are all tightly packed together in a strictly organised fashion kind of like tiles on a floor.Getting new cells (stem) to intergrate and organise correctly is an important accomplishment.Its like fitting a new tile into an already complete floor.These must become fucntional hair cells if they are improving hearing by 25db which is great.They downfall of this research is that the cells used are embryonic stem cells , not native cells of the recipient or person recieving..This can cause the organism to have an immune response to the cells and adverse effects.Also ,stem cells can and do form tumors this problem is a statistical one at present.The fact the animal models hearing has survived several weeks is encouraging.I think it will be a race between stem cells and regenerative gene therapy but believe we will see gene therapy hit clinical trials first.Probably one day the two therapies will be combined to produce near perfect hearing.Genvec has recently publicised that that they are no longer continuing with there TNF anti-cancer study because of weak results for pancreatic cancer.Sad to see this but there is one positive in this outcome and that is they now are intesifying their resources into the hearing loss program with Novartis and there are talks of a clinical trail.The genvec program is targeting age related hearing loss amonst other forms.Its stated on there website.It means Genvec intends to invent a treatment without a window period.The hair cells are required for hearing complete their task with the help off support cells that nourish and support metabolism.They are connected to hair cells and can also mechanically influence hair cell sensitivity.It is the support cells that are the targetadenovirus transported ahoh gene therapy.These cells transdifferentiate into hair cells.Take hair cell form when expressing the atoh gene making healthy functional hair cells.There are a few downfalls of gene therapy for regeneration of the inner ear.The problem is 10 days after haircells are damaged and die (noise / medication) the support cells that are needed to change start to die or change their cell form making the atoh less effective.Some damaged regions of support cells will entirely change to what is called flat epithelium (scar tissue) which atoh has little effect.This is why a 10 day window is a big help for atoh therapy effectiveness.Some hair cells have been found to be unnatural , (ectopic hair cells) that grow in places where hair cells do not normally grow but it is not known if they will assist ear function.If support cells are changed to hair cells what will replaces the support cells afterwards.These things must have been considered by genvec scientists all they would not be considering age related / long term hearing loss.There are also genes that can induce proliferation of support cells which could be of great influence to recovery of the cochlear inner ear.Providing a garden of support cells to grow into hair cells.Hopefully these support cells are being targeted for regeneration as well.The sooner a trial starts the better.Best Regards."

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