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Nasal Cells, iPS Cells and Adult Stem Cells—The Advance of Regenerative Medicine

A Polish fireman whose spinal cord was completely severed due to a knife attack has regained the limited ability to walk, thanks to a successful transplant [1]of his own nasal cells into the site of the injury.  This news should certainly be found stirring since the last time that irreparably-paralyzed people were made to walk was in Palestine in the first century.

The ordinary purpose of the particular cells, called olfactory ensheathing cells (OECs), is to support and guide the regeneration of neurons in the nasal system during normal cell turnover, or after damage.  This may not sound extraordinary since most nerve types in the human body have mechanisms for regeneration and repair.  But this is not, as a rule, true with cells of the central nervous system (CNS), which is why spinal injuries can result in lifelong paralysis.  Science has struggled to explain why the neurons of the mature mammalian CNS do not regenerate.  And overcoming this limitation in the repair systems of the human body has been a holy grail of medicine for over a century.  By harnessing the power of OECs, this grail is now within reach.

Professor Geoffrey Raisman, from the Spinal Repair Unit at University College London, began experimenting [2] in the 1980s with OECs.  He observed that the cells were able to assist the growth and repair of neurons in the olfactory system, which includes CNS neurons.  If they could aid regeneration in one part of the CNS, he reasoned, perhaps they could do it in another part.  He looked first for proof of principle in rats.  He extracted OECs from the animals and inserted them at the site of spinal cord breaches.  In 1997, he published [3] his findings: OECs reversed paralysis in rats.  Raisman has been working ever since to translate the success to humans.

A team of neurosurgeons at Wroclaw University Hospital in Poland cut into the skull of the paralyzed fireman, Darek Fidyka (38 years old), and removed the left olfactory bulb, a small structure in the forebrain rich in its supply of OECs.  The cells were cultured and then transplanted to the site of his spinal cord injury along with strips of ankle nerves to act as supports upon which the new nerves might grow.  The results were remarkable.  The OECs assisted the severed spinal nerve fibers to grow and reattach.  Not only can Mr. Fidyka walk again with the help of a walker, but he has regained sensation in his legs and bladder, some sexual function, and has seen new muscle growth in his left thigh.

OECs are not stem cells.  They are mature adult cells.  They are, however, like adult stem cells in one extraordinary way.  Their clinical promise requires no bargain with the devil to become a reality, no Mephistophelian exchange of life for life, as does embryonic stem cell research.  And although harvesting them does involve delicate neurosurgery, the removal of an olfactory bulb can be performed without a patient losing the sense of smell.

Stumbling behind like a drunken uncle in the race for cures is embryo destructive stem cell research.  On October 14, the results of a three-year long study by the Massachusetts biotech firm Advanced Cell Technology [4] (ACT) were published [5]to great fan fare in the British journal, The Lancet.  What was the milestone?  A cure for AIDs, colon cancer, perhaps insomnia?  No.  ACT announced that for the first time in an FDA-approved stem cell trial in humans, “differentiated stem cell progeny seem to survive, and do so without safety signals.”  Let me unpack this a bit: ‘the stem cells didn’t die and neither did the patients.’

ACT’s tests were performed on 18 people who suffered from the disabling eye disease known as macular degeneration.  The protocol required human embryos to be destroyed and their stem cells harvested.  The cells were then coaxed to generate specialized retina cells and then transplanted into the visually disabled patients.  Their impairment was not cured, but after 22 months, no serious side effects were observed.

After sixteen years and billions of dollars spent, some would say wasted, embryonic stem cells have only just approached the starting line.

What if the ACT protocol turns out—down the road—to be effective for treating macular degeneration?  Will this justify the killing of human embryos required to perfect and perpetuate the treatment?  If, as Dignitas Personae [6] (no. 5) teaches, human life from its embryonic origins possesses the intrinsic dignity proper to persons, then destroying embryos in order to develop ‘life saving remedies’ is a gross caricature of medicine’s true therapeutic purpose.

iPS Cells

But even those who are doubtful about the moral status of embryos would surely prefer clinical alternatives that do not require the killing of nascent human life, at least if they were available.  With this in mind, we should warmly greet the announcement on September 16 in the journal Nature [7] that a similar safety study with macular degeneration had been completed in Japan using morally legitimate induced pluripotent stem (iPS) cells (discussed here at Culture of Life at 1 [8]and 2 [9] ).

In July 2013, the authority that regulates scientific research in Japan approved the first clinical trials using induced pluripotent stem cells (iPScs) on a woman suffering from macular degeneration.  The research team at the RIKEN Center [10]for Developmental Biology in Kobe, Japan, collected ordinary skin cells from the patient, reprogrammed the cells into iPS cells, and then coaxed the undifferentiated cells into retinal tissue.  In early September 2014, the tissue was transplanted into the visually-impaired woman.  RIKEN has reported that no serious side effects have been observed.  The jury is still out as to whether longer-term side effects might still occur, and researchers do not think that the patient’s vision is likely to improve.  But at present the treatment is free of serious side effects.

Adult Stem Cells

In the world of adult stem cell (ASC) research, the journal Stem Cells recently accepted for publication [11] a study demonstrating that toxin-releasing ASCs can successfully destroy brain tumors in animal studies.  The team led by a neuroscientist from the Harvard Stem Cell Institute engineered ASCs (from adipose tissue, blood and bone marrow) to make and secrete “cytotoxins” that kill brain cancer cells without themselves being harmed or harming other healthy cells.  These toxins have been used since the late 1990s to target and kill blood cancers.  But they have been less effective on solid tumors.  By delivering the loaded stem cells to the site of the tumors inside a capsule of biodegradable gel, the cancer killing ASCs were able to successfully deliver the toxins and kill the cancer cells; and the animals’ lives were prolonged.  The researchers expect [12] to begin clinical trials of the method within five years.

 

Bioethics
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A Polish fireman whose spinal cord was completely severed due to a knife attack has regained the limited ability to walk. This is stirring news since the last time that irreparably-paralyzed people were made to walk was in Palestine in the first century.
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