Biosynthetic Corneas Restore Vision in Humans

Biosynthetic Corneas Restore Vision in Humans

  10:26:00 AM    Science Lover

---

A new study from researchers in Canada and Sweden has shown that biosynthetic corneas can help regenerate and repair damaged eye tissue and improve vision in humans. The results, from an early phase clinical trial with 10 patients, are published in the August 25th, 2010 issue of Science Translational Medicine.

Dr. May Griffith displays a biosynthetic cornea that can be implanted into the eye to repair damage and restore sight. (Credit: Photo courtesy of the Ottawa Hospital Research Institute)

"This study is important because it is the first to show that an artificially fabricated cornea can integrate with the human eye and stimulate regeneration," said senior author Dr. May Griffith of the Ottawa Hospital Research Institute, the University of Ottawa and Linköping University. "With further research, this approach could help restore sight to millions of people who are waiting for a donated human cornea for transplantation."

The cornea is a thin transparent layer of collagen and cells that acts as a window into the eyeball. It must be completely transparent to allow the light to enter and it also helps with focus. Globally, diseases that lead to clouding of the cornea represent the most common cause of blindness. More than a decade ago, Dr. Griffith and her colleagues began developing biosynthetic corneas in Ottawa, Canada, using collagen produced in the laboratory and moulded into the shape of a cornea. After extensive laboratory testing, Dr. Griffith began collaborating with Dr. Per Fagerholm, an eye surgeon at Linköping University in Sweden, to provide the first-in-human experience with biosynthetic cornea implantation.

Together, they initiated a clinical trial in 10 Swedish patients with advanced keratoconus or central corneal scarring. Each patient underwent surgery on one eye to remove damaged corneal tissue and replace it with the biosynthetic cornea, made from synthetically cross-linked recombinant human collagen. Over two years of follow-up, the researchers observed that cells and nerves from the patients' own corneas had grown into the implant, resulting in a "regenerated" cornea that resembled normal, healthy tissue. Patients did not experience any rejection reaction or require long-term immune suppression, which are serious side effects associated with the use of human donor tissue. The biosynthetic corneas also became sensitive to touch and began producing normal tears to keep the eye oxygenated. Vision improved in six of the ten patients, and after contact lens fitting, vision was comparable to conventional corneal transplantation with human donor tissue.

"We are very encouraged by these results and by the great potential of biosynthetic corneas," said Dr. Fagerholm. "Further biomaterial enhancements and modifications to the surgical technique are ongoing, and new studies are being planned that will extend the use of the biosynthetic cornea to a wider range of sight-threatening conditions requiring transplantation."

This research was supported by grants from the Canadian Stem Cell Network, the Swedish Research Council and County of Östergötland and a European Union Marie Curie International Fellowship. Initial work in developing the biosynthetic corneas was supported by the Natural Sciences and Engineering Research Council of Canada and the Canadian Institutes of Health Research. Recombinant human collagen type III used in formulating the biosynthetic corneas for the clinical study was provided by FibroGen, Inc., San Francisco, CA, U.S.A.

Dr. May Griffith is a Senior Scientist at the Ottawa Hospital Research Institute, Professor at the University of Ottawa (Faculty of Medicine) and Professor of Regenerative Medicine and Director of the Integrative Regenerative Medicine Centre at Linköping University. Dr. Per Fagerholm is a Professor of Ophthalmology at Linköping University. Dr. Neil Lagali is a senior lecturer at Linköping University. Other authors are listed in the paper.

Read More

Contact Lenses Loaded With Vitamin E May Treat Glaucoma

Contact Lenses Loaded With Vitamin E May Treat Glaucoma

  1:30:00 AM    Science Lover

---

The popular dietary supplement vitamin E, loaded into special medicated contact lenses, can keep glaucoma medicine near the eye -- where it can treat that common disease -- almost 100 times longer than possible with current commercial lenses, scientists report.

Contact lenses containing vitamin E like the one above can treat glaucoma, the second leading cause of blindness, and other eye conditions, scientists are reporting. (Credit: Anuj Chauhan, Ph.D.)

In a presentation at the 239th National Meeting of the American Chemical Society (ACS) in San Francisco, they described use of vitamin E to develop contact lenses that may deliver more medication for glaucoma and perhaps other diseases to the eye.

Anuj Chauhan, Ph.D., who headed the research team, explained that glaucoma is second only to cataracts as the leading cause of vision loss and blindness in the world. It affects almost 67 million people. Eye drops that relieve the abnormal build-up of pressure inside the eye that occurs in glaucoma, are a mainstay treatment.

"The problem is within about two to five minutes of putting drops in the eye, tears carry the drug away and it doesn't reach the targeted tissue," said Chauhan, who is with the University of Florida in Gainesville. "Much of the medicine gets absorbed into the bloodstream, which carries it throughout the body where it could cause side effects. Only about one to five percent of drugs in eye drops actually reach the cornea of the eye."

Chauhan and colleagues have developed a new extended-release delivery approach incorporating vitamin E into contact lenses. The invisible clusters, or aggregates, of vitamin E molecules form what Chauhan describes as "transport barriers." that slow down the elusion of the glaucoma medication from the lens into the eye. The drug released from the lens into the eye stays in the tears far longer than the 2-5 minutes with eye drops, leading to more effective therapy.

"These vitamin structures are like 'nano-bricks'," Chauhan said. "The drug molecules can't go through the vitamin E. They must go around it. Because the nanobricks are so much bigger than the drug molecules -- we believe about a few hundred times bigger -- the molecules get diverted and must travel a longer path. This increases the duration of the drug release from the lenses."

In research with laboratory animals, the lenses containing vitamin E nanobricks administered drugs up to 100 times longer than most commercial lenses. The lenses could be designed for continuous wear for up to a month, Chauhan said. In addition to treating glaucoma, the contacts could help other eye conditions, such as cataract and dry eye. Cataract is a clouding of the lens of the eye, and dry eye involves decreased production of tears. It affects about 2 in 10 people and can lead to more severe eye problems.

"Vitamin E is a proven nutraceutical that in small amounts is good for the eye because of its ant-oxidant properties. Also Vitamin E presence in the contact lenses blocks UV radiation, leading to increased protection against the UV light. Our research has shown that the vitamin can be loaded into the lenses without any reduction in transparency. We believe it could be helpful in disease treatment and in prevention as well," he said.

Chauhan said that clinical trials of the new lenses could begin within a year to 2 years.

Here is an excerpt from Chauhan's ACS presentation:

"We have developed a novel approach of extending the duration of drug release from contact lenses by including nanosized aggregates of Vitamin E in the lenses. The Vitamin E nano-aggregates force the drug molecules to travel in a tortuous path leading to increased drug release durations. Another benefit of Vitamin E incorporation is that Vitamin E is known to be an anti-oxidant, whose slow release from lenses could also help in prevention of ophthalmic diseases like cataract and glaucoma. Furthermore, Vitamin E blocks UV radiation, leading to reduced ocular damage from the UV light. Our research has shown that Vitamin E can be loaded into the lenses without any reduction in transparency. The drug release durations from Vitamin E loaded lenses are about 100 times longer than from commercial lenses for several ophthalmic drugs including glaucoma drug timolol, anti-inflammatory drug dexamethasone, and anti-viral drug flucanozole. Thus, Vitamin E loaded lenses could be highly effective in synergistic prevention and treatment of ophthalmic diseases through extended delivery of the desired drugs and the nutraceutical Vitamin E. Animal studies in beagle dogs are ongoing to explore glaucoma treatment through Vitamin E laden contact lenses."

Read More

Stem Cells Cultured On Contact Lens Restore Sight In Patients With Blinding Corneal Disease

Stem Cells Cultured On Contact Lens Restore Sight In Patients With Blinding Corneal Disease

  8:12:00 PM    Science Lover

---

In a world-first breakthrough, University of New South Wales (UNSW) medical researchers have used stem cells cultured on a simple contact lens to restore sight to sufferers of blinding corneal disease.

Dr. Di Girolamo and Dr. Watson.
(Credit: Image courtesy of University of New South Wales)

Sight was significantly improved within weeks of the procedure, which is simple, inexpensive and requires a minimal hospital stay.

The research team from UNSW’s School of Medical Sciences harvested stem cells from patients’ own eyes to rehabilitate the damaged cornea. The stem cells were cultured on a common therapeutic contact lens which was then placed onto the damaged cornea for 10 days, during which the cells were able to re-colonise the damaged eye surface.

While the novel procedure was used to rehabilitate damaged corneas, the researchers say it offers hope to people with a range of blinding eye conditions and could have applications in other organs.

A paper detailing the breakthrough appears in the journal Transplantation this week.

The trial was conducted on three patients; two with extensive corneal damage resulting from multiple surgeries to remove ocular melanomas, and one with the genetic eye condition aniridia. Other causes of cornea damage can include chemical or thermal burns, bacterial infection and chemotherapy.

“The procedure is totally simple and cheap,” said lead author of the study, UNSW’s Dr Nick Di Girolamo. “Unlike other techniques, it requires no foreign human or animal products, only the patient’s own serum, and is completely non-invasive.

The surgeon who carried out the procedure and managed the patients was UNSW senior lecturer, Dr Stephanie Watson.

"The operation is relatively non-invasive. The patient merely comes into the hospital for a couple of hours to have their eye prepared and the lens put in place, and then they're able to go home," she said.

“There’s no suturing, there is no major operation: all that’s involved is harvesting a minute amount – less than a millimeter – of tissue from the ocular surface,” said Dr Di Girolamo.

“If you’re going to be treating these sorts of diseases in third world countries all you need is the surgeon and a lab for cell culture. You don’t need any fancy equipment.”

Because the procedure uses the patient’s own stem cells harvested from their eye, it is ideal for sufferers of unilateral eye disease. However, it also works in patients who have had both eyes damaged, Dr Di Girolamo said.

“One of our patients had aniridia, a congenital condition affecting both eyes. In that case, instead of taking the stem cells from the other cornea, we took them from another part of the eye altogether – the conjunctiva – which also harbours stem cells.

“The stem cells were able to change from the conjunctival phenotype to a corneal phenotype after we put them onto the cornea. That’s the beauty of stem cells,” Dr Di Girolamo said.

The therapeutic contact lens used in the trial was of a type commonly used worldwide after ocular surface surgery. However, of the several brands on the market, only one was suitable for growing the stem cells.

“We don’t know why. It’s probably to do with the components the manufacturers have used in that particular lens,” Dr Di Girolamo said.

The researchers are hopeful the technique can be adapted for use in other parts of the eye, such as the retina, and even in other organs. “If we can do this procedure in the eye, I don’t see why it wouldn’t work in other major organs such as the skin, which behaves in a very similar way to the cornea,” Dr Di Girolamo said.

If you like this post, buy me a beer at $3!

Read More