Tag Archives: Tissue engineering

Freedom From the Daily JAB

Indian scientists are using tissue engineering to give diabetes patients new insulin-making cells……...CLICK & SEE

Biomaterials scientist Prabha Nair is pitting her expertise of polymers to hold out a new line of hope for patients with diabetes who are dependent on insulin shots. In her laboratory, she has used two structures fashioned out of polymer materials to normalise blood sugar in rats with diabetes for up to 90 days. One of the polymer structures is designed to make insulin-secreting cells function properly, while the other is intended to protect such cells from threats that might emerge from the body’s immune system.

Nair and her colleagues at the government-funded Sree Chitra Tirunal Institute of Medical Sciences and Technology (SCTIMST), Thiruvananthapuram have combined two applications of polymers to tackle two major obstacles that have held back a promising but experimental treatment for diabetes from widespread use. The treatment, called islet cell transplantation, involves the removal of insulin-secreting cells from the pancreas of a deceased organ donor and their implantation into a patient with diabetes.

It is nearly a decade since researchers at the University of Alberta in Edmonton, Canada, demonstrated that islet cell transplantation may help patients with diabetes acquire normal blood sugar levels and achieve some level of freedom from the need for insulin.

A review of islet transplantation on 225 patients between 1999 and 2006 had revealed several benefits — including reduced need for insulin, improved blood glucose control, and lowered risk of hypoglycemia, according to the National Institute of Diabetes and Digestive and Kidney Disorders in the US. Two years after the islet transplantation, about one-third of the recipients were free of the need for insulin shots, the review suggested.

Islet cell transplantation, however, is not standard therapy yet. “There is a critical shortage of islet cells because of a shortage of organ donors,” says Nair, a scientist in the division of tissue engineering and regeneration technologies at the SCTIMST.

Patients who receive islet cells need to take immunosuppressive drugs throughout their lives to prevent their immune systems from destroying the implanted cells. These drugs have side effects including an increased risk of cancer.

The SCTIMST researchers harvested a class of cells known as pancreatic progenitor cells from mice and placed them in a cocktail of appropriate biochemicals where they turn into insulin-secreting islet-like cells.

The scientists then loaded these islet-like cells into three-dimensional scaffolds constructed out of a gelatin, a natural polymer, and polyvinylpyrrolidone, a synthetic polymer. The islet-like cells proliferate on the scaffolds and serve as a potential source of insulin.

In experiments, the scientists observed that rats with diabetes that received these islet cell-bearing scaffolds alone died within 20 days. Their scaffold cells had been attacked by the rats’ immune systems, leading to the destruction of tissue and the failure of the implantation.

“We also designed a polymer capsule to shield the implanted islet cells from the immune system,” Nair told KnowHow. When the scientists combined the scaffolding, also called tissue engineering, with encapsulation, the rats survived for up to 90 days.

The rats were models for type-I, or insulin-dependent diabetes, but researchers say the tissue engineering and encapsulation strategy may also be considered as a possible option for patients with adult-onset diabetes who need insulin injections. Given the differences in the lifespans of rats and humans, some researchers believe the 90-day freedom from insulin observed in the laboratory animals may be equivalent to several years in humans — although exactly how long is still a subject of debate.

“These results are really exciting,” says Aroop Dutta, a tissue engineering specialist and founder of ExCel Matrix Biologicals, a Hyderabad-based start-up in biomaterials and tissue engineering, who was not connected with the research in Thiruvananthapuram.

“There just aren’t enough human-derived islet cells for the large numbers of diabetes patients dependent on insulin. Animal cells or stem cell-based approaches are the only viable options as sustained sources of islet cells,” he adds.

The results of the SCTIMST’s experiments were published last Friday in the journal Acta Biomaterialia. The researchers say their use of islet cells from mice in rats with diabetes suggests that the polymer capsule that keeps the immune system at bay may facilitate xenotransplants — the use of cells or organs across species — as an option for reversing diabetes. “But there is still much work to be done,” Nair cautions.

“We’ll need to establish that this also works in large animals,” she said. The SCTIMST group plans to initiate studies in pigs with diabetes. If the technique is indeed shown to work in large animals too, it could be ready for human clinical trials within two or three years.

Source : The Telegraph ( kolkata, India)

Enhanced by Zemanta

Coming soon, the Hips and Knees that will Never Wear Out

Replacement body parts that never wear out could become a reality within a few years as the  scientists say.

Dodgy knees and hips will be repaired using tissue engineering, while donor heart valves from animals are being specially treated to last indefinitely.
Longer-lasting artificial joints are already being tested in a bid to ensure people will be able to enjoy another 50 active years.

click & see
X-ray of female pelvix with total hips replacement

Scientists at the University of Leeds Institute of Medical and Biological Engineering have launched a £50million research initiative focused on areas of the body most affected by ageing, including joints, spine, teeth, heart and circulation.

Unlike studies involving stem cells and growing ‘spare parts’ in a lab, the programme uses the body’s own regenerative systems. The Leeds scientists have developed a chemical wash that strips cells away from donated cartilage, heart valves, blood vessels and other tissue before they are put into a human body.
Research shows they become repopulated with cells within about six months. Some 40 patients have already been treated with modified heart valves in a study in Brazil.

Professor John Fisher, director of the institute and one of the world’s leading researchers into artificial joints, said research so far had shown the valves did not deteriorate and were not rejected by the body, because ‘foreign’ donor cells had all been stripped away.
The unique method of removing living cells from human and animal tissue creates a biological ‘scaffold’ that can be regenerated within the body, at the site which needs repairing.

Worn-out ligaments and cartilage in knees can be replaced with a scaffold that will eventually attract cells to make the joint last longer.

Other areas targeted for treatment are the spine  –  where discs can be replaced  –  elbow and shoulder tissues and parts of the knee. Vascular patches are being devised that seal the holes made in arteries when surgeons clear a blockage.

The technique is not suitjointsable for whole organs, however. Professor Fisher has also designed a ceramic-on-metal hip joint that reduces ten-fold the wear and tear on artificial joints.

As a result people should be able to get spare parts at an earlier age, when they are less disabled, and they could last up to 50 years, he said.

The professor added: ‘Hip have been used for nearly 50 years but nowadays people want to cycle, play tennis, even go skiing, so they have to last longer.’
He said a scaffolding transplant would cost only around £1,000 a time. It was much more expensive to grow cells outside the body, and there was a higher infection risk.

Professor Eileen Ingham, deputy director of the Institute, said stem cells were not the answer to structural replacement of wornout bits of the body such as heart valves.

She said: ‘We are working with the NHS National Blood & Transplant Tissue Services to apply it to human donor valves. Once a patient has one, it should last a lifetime.’

Professor Christina Doyle, chief executive of Xeno Medical, predicted that in 20-30 years there would be techniques capable of regenerating human tissue off-the-shelf for use in operations.

She said: ‘It will be a case of the surgeon dialling up for spare parts to be delivered in a sterilised plastic bag.’

Source:Mail Online, 20th. Oct.’09

Reblog this post [with Zemanta]

Cystourethrogram

Definition:
A cystourethrogram is an X-ray test that takes pictures of your bladder and urethra while your bladder is full and while you are urinating. A thin flexible tube (urinary catheter) is inserted through your urethra into your bladder. A liquid material that shows up well on an X-ray picture (contrast material) is injected into your bladder through the catheter, then X-rays are taken with the contrast material in your bladder. More X-rays may be taken while urine flows out of your bladder, in which case the test is called a voiding cystourethrogram (VCUG).

CLICK & SEE

By filling your bladder with a liquid dye that shows up on x-rays, your doctor can watch the motion of your bladder as it fills and empties and can see if your urine splashes backwards toward your kidneys as the bladder muscle squeezes. This kind of test can help your doctor to better understand problems with repeated urinary-tract infections or problems involving damage to the kidneys. It can also be useful for evaluating urine leakage problems.

If X-rays are taken while contrast material is being injected into the urethra, the test is called a retrograde cystourethrogram because the contrast material flows into the bladder opposite the usual direction of urine flow.

Why It Is Done
A cystourethrogram is done to:

*Find the cause of repeated urinary tract infections.
*Look for injuries to the bladder or urethra.
*Find the cause of urinary incontinence.
*Check for structural problems of the bladder and urethra.
*Look for enlargement (hypertrophy) of the prostate or narrowing (stricture) of the urethra in men.
*Find out if urinary reflux is present. See a picture of abnormal backflow of urine.
*Look more carefully at abnormalities first found by intravenous pyelography.

How To Prepare
Tell your doctor before the test if:.

*You are or might be pregnant.
*You have symptoms of a urinary tract infection.
*You are allergic to the iodine dye used in the contrast material or any other substance that contains iodine. Also tell your doctor if you have asthma, are allergic to any medicines, or have ever had a serious allergic reaction (anaphylaxis), such as after being stung by a bee or from eating shellfish.

*Within the past 4 days, you have had an X-ray test using barium contrast material, such as a barium enema, or have taken a medicine (such as Pepto-Bismol) that contains bismuth. Barium and bismuth can interfere with test results.

*You have an intrauterine device (IUD) in place.

You may be asked to sign a consent form authorizing this procedure. Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?) .

If you are breast-feeding, give your baby formula for 1 to 2 days after the test.

How It Is Done

A cystourethrogram is done by a urologist or a radiologist. The doctor may be assisted by an X-ray technologist. You usually will not have to be admitted to the hospital.

You will need to take off all or most of your clothes, and you will be given a cloth or paper covering to use during the test. You will be asked to urinate just before the test begins.
You will be asked to wear a hospital gown and  lie on your back on an X-ray table. Your genital area will be cleaned and draped with sterile towels. Men may be given a lead shield that covers their genitals to protect them from radiation. But women’s ovaries cannot be shielded without blocking the view of the bladder.

A part of your genital area is cleaned with soap on a cotton swab. Then a soft, bendable rubber tube called a urinary catheter is inserted into your bladder, usually by a nurse. The tube is first coated with a slippery jelly and then pushed gently through the opening of the urethra (at the end of the penis for men and near the opening of the vagina for women).

CLICK & SEE

A sterile flexible cystoscope in an operating theatre

A catheter will be placed through your urethra and into your bladder. Contrast material will then slowly be injected through the catheter until your bladder is full.

You will feel some pressure while the tube slides into the urethra. Once it is in place, a tiny balloon on the end of the tube is filled with air to hold it in position. The other end (about 6 inches of tubing) hangs outside of your vagina or penis. The doctor uses this tube to fill your bladder with fluid containing a dye that shows up on x-rays. You will feel pressure in your bladder as it begins to expand.

To create a clear picture, your bladder needs to be filled with as much fluid as it can hold. You will probably feel a very strong urge to urinate. A few pictures are taken with the bladder completely full, and then the balloon is emptied and the tube is pulled out. You are given a urinal container or a bedpan and asked to urinate while you are still on the table under the x-ray camera. Several pictures are taken while your bladder is emptying. Many patients find this part of the test embarrassing, but it is routine and the doctor thinks nothing of it.

X-rays will be taken when you are standing up and sitting and lying down. The catheter is removed and more X-rays will be taken while you are urinating. You may be asked to stop urinating, change positions, and begin urinating again. If you are unable to urinate in one position, you may be asked to try it from another position.

After the test is over, drink lots of fluids to help wash the contrast material out of your bladder and to reduce any burning on urination.

This test usually takes 30 to 45 minutes.

How It Feels
You will feel no discomfort from the X-rays. The X-ray table may feel hard and the room may be cool. You may find that the positions you need to hold are uncomfortable or painful.

You will feel a strong urge to urinate at times during the test. You may also find it somewhat uncomfortable when the catheter is inserted and left in place. You will have a feeling of fullness in your bladder and an urge to urinate when the contrast material is injected. You may be sore afterward. If so, soaking in a warm tub bath may help.

You may feel embarrassed at having to urinate in front of other people. This procedure is quite routine for the X-ray staff. If you find yourself feeling embarrassed, take deep, slow breaths and try to relax.

During and after the test you may feel a burning sensation when you urinate. You may need to urinate frequently for several days after the test. You may also notice some burning during and after urination. Drink lots of fluids to help decrease the burning and to help prevent a urinary tract infection.

Risks Factors:
A cystourethrogram does not usually cause problems. Occasionally this test may lead to a urinary tract infection. If the contrast material is injected with too much pressure, there is some chance of damage to the bladder or urethra.

There is a small chance of having an allergic reaction to the x-ray dye used in the test. Some patients have some temporary irritation of their urethra after the tube has been in place, and this might result in some burning during urination for a few hours afterward. Let your doctor know if burning or pain with urinating lasts longer than a day; this could mean you have developed an infection.

As with all x-rays, there is a small exposure to radiation. In large amounts, exposure to radiation can cause cancers or (in pregnant women) birth defects. The amount of radiation from x-ray tests is very small-too small to be likely to cause any harm. X-rays such as this kind in the pelvic area should be avoided in pregnant women, because the developing fetus is more sensitive to the risks from radiation.

There is always a slight chance of damage to cells or tissue from radiation, including the low levels of radiation used for this test. However, the chance of damage from the X-rays is usually very low compared with the benefits of the test.

After the procedure
It is normal for your urine to have a pinkish tinge for 1 to 2 days after the test. Contact your doctor immediately if you have:

*Blood in your urine after 2 days.
*Lower belly pain.
*Signs of a urinary tract infection. These signs include:
*Pain or burning upon urination.
*An urge to urinate frequently, but usually passing only small amounts of urine.
*Dribbling or leaking of urine.
*Urine that is reddish or pinkish, foul-smelling, or cloudy.
*Pain in the back just below the rib cage on one side of the body (flank pain).
*Fever or chills.
*Nausea or vomiting.

Results
A cystourethrogram is an X-ray test that takes pictures of your bladder and urethra while you are urinating. Some results may be available immediately after the cystourethrogram. Final results are usually available within 1 to 2 days.

Cystourethrogram  Normal:

*The bladder appears normal.

*Urine flows normally from the bladder.

*The bladder empties all the way.

*The contrast material flows evenly out of the bladder through a smooth-walled urethra.

Cystourethrogram  Abnormal:

*Bladder stones,
*tumors,
*narrowing or pouches in the wall (diverticula) of the urethra or bladder are seen in the bladder.

*If the test was done because of possible injury to the bladder, a tear is found in the bladder wall or urethra.

*Urine flows backward from the bladder into the ureters (vesicoureteral reflux).

*Contrast material leaks from the bladder.

*The bladder does not empty all the way.

*The prostate gland is enlarged.

What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
*Having barium (from a previous barium enema test), gas, or stool in the bowel.
*Being unable to urinate on command because of embarrassment at having to urinate in front of other people.
*Pain caused by having the catheter into the urethra. This may also cause problems with your urinary stream. You may have a muscle spasm or not be able to fully relax the muscles that control your bladder.
*A cystourethrogram is not usually done during pregnancy because the X-rays could harm an unborn baby.
Resources:
https://www.health.harvard.edu/fhg/diagnostics/cystourethrogram.shtml
http://www.webmd.com/a-to-z-guides/cystourethrogram-16691

Reblog this post [with Zemanta]

Synthetic Skin is as Good as Real

 A synthetic skin as good as the natural one is likely to be mass produced, thanks to a new technique pioneered by German scientists. The good news is that it will be a boon for burn victims, who require extensive skin grafting to cover damaged parts — a very painful process. The availability of this “artificial skin” opens up almost unlimited new possibilities for medical scientists. One of their upcoming projects is to produce intestinal tissue for resorption tests.

Tissue engineering has been at the focus of research for many years, and tissues such as cartilage or skin are already being cultured in numerous biotechnology labs.

But researchers at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart plan to go a step further. They are aiming to enable fully automated tissue production.

First of all, a biopsy is checked for sterility. A gripper arm then transports the biopsy into the automated device where the individual steps are performed, said an IGB release. The machine cuts the biopsy into small pieces, isolates the different cell types, stimulates their growth, and mixes the skin cells with collagen.

A 3-D reconstruction of different skin layers is produced with the aid of a special gel matrix – and the skin is ready. In the final step, the machine packages the cells for shipment. Alternatively, the tissue can be deep-frozen and stored for later use.

Sources:The Times Of India

Reblog this post [with Zemanta]

Medical magic: Scientists try to regrow fingers

Researchers are trying to find ways to regrow fingers and someday, even limbs with tricks that sound like magic spells from a Harry Potter novel.

There is the guy who sliced off a fingertip but grew it back, after he treated the wound with an extract of pig bladder. And the scientists who grow extra arms on salamanders. And the laboratory mice with the eerie ability to heal themselves.

CLICK & SEE

This summer, scientists are planning to see whether the powdered pig extract can help injured soldiers regrow parts of their fingers. And a large federally funded project is trying to unlock the secrets of how some ani-mals regrow body parts so well, with hopes of applying the lessons to humans.

The implications for regrowing fingers go beyond the cosmetic. People who are missing all or most of their fingers, as from an explosion or a fire, often can’t pick things up, brush their teeth or button a button. If they could grow even a small stub, it could make a huge difference in their lives.

And the lessons learnt from studying regrowth of fingers and limbs could aid the larger field of regenerative medicine, perhaps someday helping people replace damaged parts of their hearts and spinal cords, and heal wounds and burns with new skin instead of scar tissue.

But that’s in the future. For now, consider the situation of Lee Spievack, a hobby-store salesman in Cincinnati, as he regarded his severed right middle finger one evening in August 2005.

He had been helping a customer with an engine on a model airplane behind the shop when the propellor sliced off the tip of his finger. The missing piece, about one centimetre long, was never found.

An emergency room doctor wrapped up the rest of his finger and sent him to a hand surgeon, who recommended a skin graft. What was gone, it appeared, was gone forever.

Spievack did have a major advantage a brother, Alan, a former Harvard surgeon who’d founded a company called ACell Inc, that makes an extract of pig bladder for promoting healing and tissue regeneration.

It helps horses regrow ligaments, for example, and the federal government has given clearance to market it for use in people. Similar formulations have been used in many people to do things like treat ulcers and other wounds and help make cartilage.

Lee Spievack took his brother’s advice to forget about a skin graft and try the pig powder. Soon a shipment of the stuff arrived and Lee Spievack started applying it every two days. Within four weeks his finger had regained its original length, he says, and in four months “it looked like my normal finger.”

Source:The Times Of India