spinal cord stem cell

[lofulgee]

Dr Wise Young,
If there was stem cell in the spinal cord, could you please explain why no scientists have grow the stem cells in the labs and inject it back into the spine. Is it because the cell in the spine is harder to grow?

Why do the scientists use OEG cell instead of stem cell from the spine.

[Wise Young]

lofulgee,

Let me rephrase your question. Why take stem cells out of the spinal cord and inject it back, if they are already present in the spinal cord? Some scientists are asking this question because adult spinal cords have stem cells that probably are responsible for the healing of the spinal cord after injury. Stem cells in the spinal cord produce new astrocytes and oligodendroglia. New blood vessels form and the newly formed astrocytes line the surfaces of these vessels to re-form the blood brain barrier (or the blood-spinal cord barrier, as some would call it). Likewise, new oligodendroglia form to remyelinate the spinal cord. Nobody has shown, as yet, that new neurons are formed to replace ones that are lost but I suspect that this may also occur although at a slower rate and over a long period of time. Some of the therapies now being tested aim at stimulating the stem cells that are already present in the spinal cord. For example, this is supposed to be what AIT-082 (a modified guanosine analog) was supposed to do. This drug, also called neotrofin, was tried in clinical trial last year. I understand that the AIT-082 was not effective (although this has not yet been reported). This may be because the drug is not all that effective, the conditions in the injured spinal cord are not optimal for the endogenous stem cells to produce new neurons, or the endogenous stem cells are already doing their job as well as they can. Stem cells cannot do everything.

Olfactory ensheathing glia (OEG) are very special cells that seem to be desi at the task of stimulating regeneration. Note that although stem cells in the nasal mucosa can produce OEG cells that migrate up the olfactory nerve to the olfactory bulb, presumably facilitating regeneration of the olfactory nerves. To date, I don't think that anybody has shown that stem cells in the spinal cord have produced OEG cells. This does not mean that it does not occur and that the spinal cord is not producing new OEG like cells in the spinal cord. Perhaps they are not producing enough of such cells and the implantation of OEG cells helps facilitate regeneration and recovery.

Growing stem cells from adult tissues is very difficult to do. We know that they are there because we can administer labels that tell us when new cells are being produced in the tissue. We know that injury increases the number of new cells being produced in the spinal cord. It is possible that the highest priority of the stem cells in injured spinal cord is to repair the blood supply and remyelinate axons, rather than to regenerate the spinal cord.

Wise.

[Sfajt]

lofulgee,
Great question!
Thanks for the response Dr. Young.
I believe stem cells in the spinal cord hold great promise for a cure, hopefully they will find a way to harness their potential.

[antiquity]

Dr. Young, am I correct in saying that there's a difference between bone marrow stem cells and spinal cord stem cells. If so, I think the two are being confused.

[This message was edited by seneca on 01-01-04 at 03:35 PM.]

[Wise Young]

seneca, in 2000, Ira Black discovered that certain cells from bone marrow will express markers that suggest that they can produce neurons in culture. Several others have reported that bone marrow transplants will stimulate remyelination in the spinal cord. However, the demonstration that bone marrow cells are pluripotent and can producing functional neurons is still quite controversial. To my knowledge, nobody has reported success in growing stem cells from the spinal cord although much data suggest that there are cells in the spinal cord that can produce a variety of cells, including oligodendroglia. For a long time, the stem cells of the spinal cord were thought to be the ependymal cells. However, there is controversy about that as well.

There is much misconception about growing adult stem cells. To date, there is no known marker for adult stem cells in bone marrow. It is not even clear how many of the cells in the bone marrow are stem cells. Many people have tried to grow them without success. Finally, the concept that they can be pluripotent after transplantation has not yet been shown.

Wise.

[lofulgee]

Dr Wise Young,

[lofulgee]

Dr Wise Young,
Thank you for your reply. I really appreciate your feedback and I wish you have a Happy New Year.

In 2003, I saw a documentary in regards to scientists taking stem cells out from the pancreas and grow it in the laboratory and they re-injected the stem cell back into the pancreas to help patients with critical diabetes. This is why I raised the issue as to whether we should take stem cell from the spinal cord and grow it in the lab and re-injected into the spine.

Lofulgee.

[Faye]

Originally posted by lofulgee:

Dr Wise Young,
If there was stem cell in the spinal cord, could you please explain why no scientists have grow the stem cells in the labs and inject it back into the spine. Is it because the cell in the spine is harder to grow?

Why do the scientists use OEG cell instead of stem cell from the spine.

Stem cells from the brain have been harvested and grown/multiplied to be re-inplanted in the brain 3 months later.
Even some stem cell lines have been developed from brain stem cells by this company:

ReNeuron presents brain stem cell data at London conference

24th September 2003


ReNeuron's Chief Scientific Officer, Dr John Sinden, today provided an update on the Company's stem cell transplantation programmes at the Marcus Evans 2nd Annual International Stem Cells Conference in London.

ReNeuron has now developed an extensive collection of normal human cell lines derived from single human brain stem cells and conditionally immortalised using proprietary c-myc technology. The cell lines have all been developed to meet the current international regulatory requirements for transplantation.

More than 100 lines were initially screened by in vitro assays and the most promising have been subsequently tested in vivo for survival, differentiation and migration. Despite the cell lines behaving similarly in in vitro testing, in vivo data was essential to distinguish lines worthy of further study in long term transplant experiments.

Six cell lines showing very good in vivo properties have been selected for an ongoing evaluation in models of stroke, Huntington's disease, Parkinson's disease, and Dementia, the results from which will be known over the coming months.

Dr Sinden said:

"Our experience suggests that a combination of in vitro and in vivo screening is essential to select cells for long term transplantation experiments. Even an extensive panel of in vitro assays did not completely eliminate lines with poor in vivo survival. The best of our new cell lines show very encouraging in vivo properties which we believe will ultimately lead to success in our cell transplantation programmes."

ReNeuron has also developed a number of similar stem cell lines, known as ReNcell, that are being developed and marketed for use as a drug discovery tool. Recent data indicates that the ReNcell lines can be easily matured in vitro to produce a rich neural network containing cells which have the phenotypical and electrophysiological properties of neurones.

ReNeuron has, today, separately announced the re-registration of ReNeuron Holdings plc as a private company, ReNeuron (UK) Limited, and has also announced certain Board changes.


For further information:

Dr John Sinden, Chief Scientific Officer, ReNeuron (UK) Limited
44 (0)1483 302560

[Wise Young]

Faye, you are correct in pointing out that adult neural stem cells have indeed been cultured from brain. I was referring to stem cells from human spinal cord. McDonald, et al. (2003) recently reported successful culturing of multipotential spinal cord precursor cells. Shihabuddin (2002) had reported successful culturing of adult rodent spinal cord derived neural stem cells. Wu, et al. (2002) have isolated and immortalized cells lines from embryonic spinal cord. Tzeng (2002) likewise has isolated neural progenitor cells that can produce both neurons and glia.

Wise.

• MacDonald SC, Fleetwood IG, Hochman S, Dodd JG, Cheng GK, Jordan LM and Brownstone RM (2003). Functional motor neurons differentiating from mouse multipotent spinal cord precursor cells in culture and after transplantation into transected sciatic nerve. J Neurosurg. 98: 1094-103. Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada. OBJECT: One of the current challenges in neurobiology is to ensure that neural precursor cells differentiate into specific neuron types, so that they can be used for transplantation purposes in patients with neuron loss. The goal of this study was to determine if spinal cord precursor cells could differentiate into motor neurons both in culture and following transplantation into a transected sciatic nerve. METHODS: In cultures with trophic factors, neurons differentiate from embryonic precursor cells and express motor neuronal markers such as choline acetyltransferase (ChAT), Islet-1, and REG2. Reverse transcription-polymerase chain reaction analysis has also demonstrated the expression of Islet-1 in differentiated cultures. A coculture preparation of neurospheres and skeletal myocytes was used to show the formation of neuromuscular connections between precursor cell-derived neurons and myocytes both immunohistochemically and electrophysiologically. Following various survival intervals, precursor cells transplanted distal to a transection of the sciatic nerve differentiated into neurons expressing the motor neuron markers ChAT and the alpha1 1.2 (class C, L-type) voltage-sensitive Ca++ channel subunit. These cells extended axons into the muscle, where they formed cholinergic terminals. CONCLUSIONS: These results demonstrate that motor neurons can differentiate from spinal cord neural precursor cells grown in culture as well as following transplantation into a transected peripheral nerve.

• Shihabuddin LS (2002). Adult rodent spinal cord derived neural stem cells. Isolation and characterization. Methods Mol Biol. 198: 67-77. Genzyme Corporation, Framingham, MA, USA.

• Wu YY, Mujtaba T, Han SS, Fischer I and Rao MS (2002). Isolation of a glial-restricted tripotential cell line from embryonic spinal cord cultures. Glia. 38: 65-79. Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA. Neuroepithelial stem cells (NEPs), glial-restricted precursors (GRPs), and neuron-restricted precursors (NRPs) are present during early differentiation of the spinal cord and can be identified by cell surface markers. In this article, we describe the properties of GRP cells that have been immortalized using a regulatable v-myc retrovirus construct. Immortalized GRP cells can be maintained in an undifferentiated dividing state for long periods and can be induced to differentiate into two types of astrocytes and into oligodendrocytes in culture. A clonal cell line prepared from immortalized GRP cells, termed GRIP-1, was also shown to retain the properties of a glial-restricted tripotential precursor. Transplantation of green fluorescent protein (GFP)-labeled subclones of the immortalized cells into the adult CNS demonstrates that this cell line can also participate in the in vivo development of astrocytes and oligodendrocytes. Late passages of the immortalized cells undergo limited transdifferentiation into neurons as assessed by expression of multiple neuronal markers. The availability of a conditionally immortalized cell line obviates the difficulties of obtaining a large and homogeneous population of GRPs that can be used for studying the mechanism and signals for glial cell differentiation as well as their application in transplantation protocols.

• Tzeng SF (2002). Neural progenitors isolated from newborn rat spinal cords differentiate into neurons and astroglia. J Biomed Sci. 9: 10-6. Department of Biology, National Cheng-Kung University, Tainan, Taiwan, ROC. stzeng@mail.ncku.edu.tw. Permanent functional deficit in patients with spinal cord injury (SCI) is in part due to severe neural cell death. Therefore, cell replacement using stem cells and neural progenitors that give rise to neurons and glia is thought to be a potent strategy to promote tissue repair after SCI. Many studies have shown that stem cells and neural progenitors can be isolated from embryonic, postnatal and adult spinal cords. Recently, we isolated neural progenitors from newborn rat spinal cords. In general, the neural progenitors grew as spheres in culture, and showed immunoreactivity to a neural progenitor cellular marker, nestin. They were found to proliferate and differentiate into glial fibrillary acidic protein-positive astroglia and multiple neuronal populations, including GABAergic and cholinergic neurons. Neurotrophin 3 and neurotrophin 4 enhanced the differentiation of neural progenitors into neurons. Furthermore, the neural progenitors that were transplanted into contusive spinal cords were found to survive and have migrated in the spinal cord rostrally and caudally over 8 mm to the lesion center 7 days after injury. Thus, the neural progenitors isolated from newborn rat spinal cords in combination with neurotrophic factors may provide a tool for cell therapy in SCI patients.