Kemajuan Rawatan Menggunakan 'Stem Cells'

Apakah 'Stem Cell' ?

Sel stem atau sel induk adalah sel istimewa yang memiliki keupayaan untuk berkembang (membahagi) dalam tempoh yang tidak tetap dan boleh berubah menjadi pelbagai jenis sel yang khusus. Keupayaan yang dikenali sebagai keplastikan (plasticity) ini, adalah sifat biasa bagi telur-telur yang telah disenyawakan dan sel-sel awal embrio (juga dikenali sebagai blastomer). Telur yang telah disenyawakan dan mempunyai kebolehan untuk membentuk semua sel di dalam tubuh, mempunyai keupayaan perkembangan keplastikan yang paling tinggi. Oleh itu, ia bersifat totipoten, iaitu ia boleh berkembang menjadi embrio yang lengkap apabila diasingkan daripada kumpulan blastomer.

Sel stem terbahagi kepada dua, iaitu sel stem embrio dan sel stem orang dewasa. Apabila ditempatkan di dalam kultur, sel-sel stem ini berkembang dan mula membahagi, dan para saintis kini sedang berusaha untuk membolehkan mereka menghasilkan jenis-jenis sel yang boleh diguna pakai bagi menyembuhkan pelbagai penyakit di mana ianya akan digunakan bagi menggantikan sel-sel manusia yang telah mati seperti penyakit saraf, kegagalan jantung, kebutaan dan sebagainya.

Stem Cell Treatment Restores Vision

Study Shows Damaged Corneas May Be Regenerated With Patients' Stem Cells

A regenerative treatment that uses stem cells taken from the patient's own eyes is helping some blind patients see again.

Italian researchers report that the stem cell procedure resulted in successful corneal transplantation in three-fourths of patients with blindness in one or both eyes, caused in most patients by chemical or thermal burns.

Vision was at least partially restored in patients who did not have major damage to other parts of the affected eye, says study researcher Graziella Pellegrini, PhD, of the University of Moderna's Center for Regenerative Medicine.

Pellegrini and colleagues have performed corneal transplants in around 250 patients over the last decade using the stem cell technique, but it remains experimental and is not being done in the U.S.

Their latest study is published in the New England Journal of Medicine. The findings were also reported last week in San Francisco at a meeting of the International Society for Stem Cell Research.

"We followed the patients in this study for an average of three years and as long as a decade, and we have shown that the results can last for many years."

Regeneration of Corneas

The study included 112 patients with damaged corneas who received the stem cell treatment between 1998 and 2006.

The procedure involved extracting healthy stem cells from the limbus, which is located between the colored and white part of the eye.

Pellegrini says the procedure can be done even when only a tiny portion of the limbus remained undamaged.

Stem cells taken from the biopsied limbus tissue grew into healthy corneal tissue in a little over two weeks, she says, and the healthy tissue was then grafted onto the damaged eye.

When the procedure was successful, the damaged, opaque cornea became clear again and the eye looked normal.

In all, 77% of patients had a successful first or second graft, while the procedure was considered a partial success or failure in 13% and 10% of cases, respectively.

People with corneal damage from chemical and thermal burns often have symptoms including light sensitivity, itching, and pain. These symptoms went away or were much less severe in the successfully treated patients.

Following successful transplant, about half of the patients had further surgeries to improve visual acuity and most showed at least some improvement in vision. One patient achieved normal vision with the stem cell grafting alone.

Regenerative Treatments for Heart and Liver

University of California, Davis ophthalmology professor Ivan Schwab, MD, was among the first to perform the stem cell transplant procedure, based on Pellegrini's early work, almost a decade ago.

He treated about 15 patients, and while many showed early responses, the benefits did not last.

"This study is remarkable because these researchers have shown not only that this technique works, but that it works for up to 10 years in some cases,".

He adds that regenerative treatments show promise for a wide range of illnesses, including those involving the bladder, liver, and the heart.

"We are not talking about regenerating the entire liver or heart," he says. "The concept that you have to grow a whole liver or a whole heart is not correct."

He points out that researchers are already working on a heart "patch" that can help a damaged heart function better.

"KAEDAH TERBARU INI MASIH DALAM PERINGKAT KAJIAN, NAMUN IANYA MENJANJIKAN SEBUAH HARAPAN KEPADA PESAKIT-PESAKIT KRONIK TERTENTU. NAMUN TENTUNYA KOS RAWATAN YANG AKAN MEMBATASINYA"