STEM CELL THERAPY IN NEUROLOGICAL

DISEASES

Dr. Sunil Kumar SharmaSenior Resident

ModeratorDr. Vijay Kataria

Asst. Prof.GMC Kota

OVERVIEW

Stem cell biology is a rapidly expanding field.

In vitro as research tools for modeling human neurological diseases and drug screening.

In vivo in regenerative medicine

A BRIEF HISTORY

1968- First BMT to treat an eight-year-old boy with  (SCID).

ESCs were identified in 1998.

iPSCs has initially produced by Shinya Yamanaka at Kyoto University in 2006 .

Stem cells have two essential properties:

Self-renewal

Multipotentiality/pleuripotency.

ESSENTIAL PROPERTIES OF STEM CELLSFOR USE IN CLINICAL TRANSPLANTATION

Capable of clonal propagation in vitro

Genetic stability at high passage

Integration within the host brain following transplantation

… Migration and engraftment at sites of

damage

Correct differentiation into appropriate neural cell types

Functional benefits

Lack of side effects

TYPES Totipotent cells- can form an entire

organism autonomously. (e.g. zygote.)

Pluripotent cells- can form almost all of the body’s cell lineages (endoderm, mesoderm, and ectoderm), including germ cells(e.g., ESCs) .

Multipotent cells- can form multiple cell lineages(e.g., HSCs)

Oligopotent cells- can form more than one cell lineage but are more restricted than multipotent cells(e.g.,NS cells)

Unipotent cells or monopotent cells- can form a single differentiated cell (e.g. spermatogonial stem [SS] cells)

NERVE CELL CANNOT REGENERATE ?

In 1913 the great Spanish neuroscientist Santiago Ramón y Cajal pronounced “that in adult centres the nerve paths are something fixed, ended, immutable. Everything may die, nothing may be regenerated”.

For many years neuroscientists believed that no process to replace lost neurons existed in our brain. Santiago Ramón

y Cajal(1852-1934)

SITES OF ADULT NEURONAL STEM CELLSSubventricular zone(SVZ) of lateral ventricles and the Subgranular zone of dentate gyrus in hippocampus.

SOURCES OF STEM CELLS

Human embryonic stem cells (ESC)

Human umbilical cord blood cells (UCB)

Immortalised cell lines

Foetal neural stem cells

Adult neural stem cells (NSC)

Bone marrow derived cells

Induced pluripotent cells (iPS)

HUMAN EMBRYONIC STEM CELLS (ESCS)

Derived from the inner cell mass of the embryonic blastula(Pleuripotent)

Can provide an unlimited source of cells

Can be directed into neural precursors to generate neurons, oligodendroglia and astrocyte both in vitro and in-vivo.

HUMAN UMBILICAL CORD BLOOD CELLS (UCB) Derived from umbilical cord blood

Can differentiate into neural lineages

Produced progeny that shows positivity of neural and glial cells markers

Experimental data in animal models of stroke have shown functional benefits

A better understanding of these cells is needed before clinical transplantation studies ensue

IMMORTALISED CELL LINES

As there is Ethical difficulties in transplanting embryonic cells .

Derived by infecting neuroepithelial precursor cells from predefined CNS regions before terminal mitosis, with a retrovirus encoding an immortalizing oncogene.

FOETAL NEURAL STEM CELLS

Harvested from the post-mortem human fetal brain

Maintain a normal karyotype for a significant number of passages in culture .

Can produce a large number of neurons and astrocytes.

High proliferative capacity without any evidence of tumorogenesis .

ADULT NEURAL STEM CELLS (NSC)

Multipotent stem cells found in developed organisms

Identified within bone marrow, brain, heart, skin and bone.

1-2% of the total cell population within a particular tissue type.

ADULT NEURAL STEM CELLS (NSC)…

Usually quiescent and in an undifferentiated state .

Their proliferative capacity is limited.

Can generate neurons, astrocytes and oligodendrocytes,

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SOURCES OF SCS Autologous-

Source- peripheral blood, cord blood, bone marrow , skinBenefit- no risk of rejection

Allogeneic-Source- HLA matched relative or unrelated donorLimitations- HistocompatibilityFetal tissue is also used, raising ethical issues.

Xenogenic- Source- porcine fetal ventral mesencephalic (FVM) cells

Limitations- Life long immunosupression and risk of rejection.

BONE MARROW DERIVED CELLS

Mobilized Peripheral Blood (MPB) and MSCs are clinical source of HSCs.

MPB contains a mixture of hematopoietic stem and progenitor cells

These cells have the potential to regenerate the brain tissue by release of neurotrophic growth hormones

INDUCED PLURIPOTENT CELLS (IPS)

Similar to human embryonic stem cells

Adult human cells from skin were transformed to a pluripotent state using genetic engineering techniques

Can differentiate into cell types of all the three germ layers.

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Embryonic S.C. Adult S.C.From blastocysts , In-Vitro Fertilization and aborted fetuses

Stem cells have been found in the blood, bone marrow, liver, kidney, brain, etc

“Pluripotent”(can become any cell)

“Multipotent”(can become many but not any)

Stable. Can undergo many cell divisions.

Less Stable. Capacity for self-renewal is limited.

Easy to obtain but blastocyst is destroyed.

Difficult to isolate in adult tissue.

Possibility of rejection?? Host rejection is minimal Ethical issues No ethical issues

NUCLEAR REPROGRAMMING

N. Development -totipotent (zygote) – pluripotent cells(blastocyst) - multipotent fertilized cells -terminally differentiated cells.

The reversal of the terminally differentiated cells to totipotent or pluripotent cells (called nuclear reprogramming).

Achieved by using nuclear transplantation, or nuclear transfer (NT), procedures(“cloning”), where the nucleus of a differentiated cell is transferred into an enucleated oocyte.

iPS- An alternative approach that has become a

method of choice is induced pluripotent stem [iPS] by using various transcription factors(TFs)

Direct reprogramming- To convert one type of terminally differentiated

cell (e.G., Fibroblast cell) into another type of terminally differentiated cell (e.G., Cardiac muscle, neuron, or hepatocyte) by overexpressing specific sets of TFs .

This technology is currently limited by its low efficiency

Lineage commited multipotent stem cells can show transdifferentiation. e.g., HS cells may be converted into neurons as well as germ cells.

Tissue stem cells can be derived directly from a patient for therapeutic purposes.

GOAL OF STEM CELL THERAPY

Different body tissues/organs have different regenerative potentials after injury.

To promote cell replacement in organs that are damaged beyond their ability to self-repair.

NEUROLOGICAL DISEASES Trauma-SCI

Vascular-Stroke

Degenerative- Parkinson’s disease, Huntington’s chorea, Amyotrophic lateral sclerosis, AD etc.

Chronic inflammatory and immune mediated- multiple sclerosis

Genetic diseases in children- neuronal ceroid lipofuscinosis, mucopolysaccharidoses, Leucodystrophies and muscular dystrophies.

PARKINSON’S DISEASE (PD)

Preferential death of DA neurons in the SNc .

To date, more than 300 cases of the fetal tissue engraftment have been performed worldwide.

Two double-blind and placebo-controlled clinical trials failed to prove the efficacy [Freed et al., 2001; Olanow et al., 2003].

PARKINSON’S DISEASE (PD)

In 2002, Kim et al. differentiated mouse ESCs (mESCs) into DA neural precursors and transplanted into a rodent model of PD.

Showed the potential role of ESC-mediated cell therapy for PD treatment .

Teratoma formation

Reprogramming methods that convert fibroblasts or other types of somatic cells directly into neural precursors or DA neurons have recently been developed [Caiazzo et al., 2011; Kim et al., 2011].

BM-MSCs, placenta-derived MSCs, ADSCs, have shown to reverse behavioral dysfunctions in animal models of PD.

Currently undergoing clinical trials for PD are using BM-MSCs as an autologous cell source for transplantation

A ongoing clinical trial in India to evaluate the therapeutic effect of BM-MSCs after transplantation into the striatum of PD Pt showed that Three of seven patients had steady improvement in their “off”/”on” UPDRS and Hoehn and Yahr (H&Y) score.

STROKE

Neuronal cells derived from neural progenitors were transplanted into 12 patients from 6 months to 6 years after basal ganglia strokes.

No adverse events were observed up to 5 years after transplantation and the patients displayed some clinical improvement.

STROKE Human trials for evaluating the long-term(5

years) safety and efficacy of i.v. MSC transplantation showed significant improvement in MRS score in study group (Lee JS et al 2010)

The currently existing clinical data are still limited and cannot provide consistent evidence of clinical efficacy(Andres RH et al)

HUNTINGTON’S DISEASE (HD)

HD is a progressive autosomal dominant disease caused by the expansion of CAG triplet repeats (chromosome 4).

Bachoud-Levi et al. [2000- 2006] intrastriatal transplantation of fetal striatal cells conferred a certain degree of motor and cognitive improvements for 2–3 years, but not permanently.

BM-MSCs overexpressing brain-derived neurotrophic factor (BDNF) or nerve growth factor were shown to be effective in restoring motor functions in a YAC128 transgenic mouse model of HD [Dey et al., 2010].

AMYOTROPHIC LATERAL SCLEROSIS (ALS)

Fatal neurodegenerative disease caused by the death of upper and lower motor neurons.

Stem cell-mediated therapeutic approaches target -direct cell replacement -modulation of a microenvironment by secreting

trophic factors.

The goals are - reconstructing the destroyed neural circuitry -delaying/preventing motor neuron death.

AMYOTROPHIC LATERAL SCLEROSIS (ALS) MSC transplantation into the spinal cord has

been reported to delay motor neuron decline and improve motor performance in the mouse model of ALS

Deda et al-2009, treated 13 ALS patients with bone marrow-derived MSC injected into the cervical spinal cord. Of these, 9 patients improved 1 year after treatment, 1 was stable, and 3 patients died soon after the procedure

ALS Trials indicate the short-term safety and feasibility of

stem cell treatment in ALS but long-term safety and efficacy have yet to be proven

Studies in SOD1 mutant mice demonstrated that transplanted whole bone marrow delayed disease onset, increased life span, and slowed motor neuron loss

Karumbayaram et al.Created motor neurons from human iPSCs and showed that these neurons were indistinguishable from embryonic stem cells.

Clinical trials with NSC or iPSCs in ALS are under way

ALS Till date, one Indian open label pilot study has

been published to assess the feasibility, efficacy and safety of autologous bone marrow-derived stem cells in patients of ALS .

Showed improvement in the ALS Functional Rating Scale (ALSFRS-R) score at 90, 180, 270 and 365 days post therapy.

No significant adverse events or deterioration in ALSFRS-R composite score from baseline is noted at one-year follow-up (p=0.090) [Prabhakar S, et al. (2012)].

MULTIPLE SYSTEM ATROPHY (MSA)

Animal models showed MSC had a protective effect against progressive dopaminergic and striatal neuronal loss.

A recent published placebo-controlled randomized clinical trial of autologous MSC in patients with MSA revealed significant indications of beneficial effects in mild to moderate MSA patients(Lee PH, et. al. 2012)

MULTIPLE SCLEROSIS MSC injection, intravenously or into the CSF,

strongly suppressed the clinical and pathological signs and reversed disability.

Re-myelination was evident in the MSC-treated animals, accompanied by neuroprotection [Gerdoni , et al-2007].

At 6 months, a trend towards improvement in the disability scores, was observed

MULTIPLE SCLEROSIS A recently reported phase 2a study in 10

patients with secondary progressive MS showed an improvement in visual acuity and visual evoked response latency, following intravenous transplantation of autologous MSC.

15 patients with progressive MS were transplanted with peripheral blood hematopoietic stem cells.

In a six month follow-up, neurologic improvement was detected in a substantial proportion(Fassas A, et. al -1997) .

MULTIPLE SCLEROSIS Ni et al. also reported the safety and efficacy

of autologous hematopoietic stem cells transplantation in 21 progressive MS patients during a follow up of 3 years

A recent study showed that AHSCT had a sustained beneficial effect in aggressive MS cases unresponsive to conventional therapies, especially in relapsing forms of MS(Mancardi GL et al 2012)

The associated neurodegeneration is too widespread and diffuse.

Therefore unlikely to be ameliorated by adding more cells to the system.

Disease-specific ESC lines could be used to study the degeneration of neurons in vitro.

ALZHEIMER’S DISEASE

SPINAL CORD INJURY

Traumatic spinal cord injuries are one of the challenging problems

A study was conducted in which 100 (69 males and 31 females) spinal cord injury patients were implanted with autologous stem cells injection with an average of 4.5 years of disease(Ravikumar R, et al -2007)

Showed significant Improvement in motor power,sensory symptoms and bladder dysfunction (6 months follow up).

MUSCLE DISEASES In dystrophic mice, BMSC were able to migrate

and contribute to the formation of new muscle fibers after BMT.

The latter study have shown that ∼80% of BM-derived muscle-incorporated nuclei were ‘silent’.

In humans, there has been a clinical report of a young patient with Duchenne muscular dystrophy (DMD), who, 12 years after BMT, showed donor nuclei fused to 0.5% of the dystrophic myofibers.(Gussoni E, et al 2002)

CEREBRAL PALSY

An open label study of intra-arterial infusion of autologous BMSC in thirty (n=30) patients with cerebral palsy(Srivastava MVP, et al 2011)

No adverse events on a 12 months follow up

Functional improvement in all clinical scales(muscle power, spasticity, dystonia, abnormal Movements, modified Barthel Index).

A PARTIAL LIST OF PUBLISHED PILOT CLINICAL STUDIES WITH STEM CELL TRANSPLANTATION AND OTHER CELL THERAPIES, IN VARIOUS NEUROLOGICAL DISEASES

INDIAN STUDIES

CURRENT STATUS OF STEM CELL APPROACHES IN HUMAN DISORDERS IN INDIA

At present, the only approved indications - hematopoietic stem cells in hematological disorders.

Till date no neurological disorder have been approved for Stem cell therapy.

UNRESOLVED ISSUES WITH THE CELL THERAPY The optimal type of cells,

Dosage of cell

Optimum timing of treatment;

Optimum route of delivery

Outcome measures; primary safety end points and efficacy measurements.

Other areas of interest include –

In-vivo tracking of transplanted cells.

Labelling of cells with a magnetic label (eg Super paramagnetic iron oxide particles)-MRI tracking

Long-term biosafety studies are essential because of potential for tumorogenicity.

Appropriate quality assurance and control standards must be in place to allow the standardization of cell preparations

ROLE OF NEUROLOGIST

Best resource to counsel patients with neurological disorders

Discussions with their patients on the feasibility, prospects, and potential ill effects of the use of stem cells.

To educate the patient.

Irreversibility of the procedure

CONCLUSION

Stem cells are safe and feasible when transplanted in neurodegenerative, inflammatory and ischemic neurological diseases.

As cell therapy is in its nascent stage, a conclusive evidence of efficacy would want more number of studies to be undertaken.

Cell transplantation worldwide needs a stringent regulation under social, financial, medical and legal contexts .

A premature translation of crude data and concepts can bring new hypes but may not prove meticulous for diseases.

Thank You

REFERENCES

Clinical experience with stem cells and other cell therapies in neurological diseases (Dimitrios Karussis ⁎, Panayiota Petrou, Ibrahim Kassis-2012)

Stem Cells in Neurological Diseases: Indian Perspective (Ashu Bhasin, Padma Srivastava MV, Rohit Bhatia, Senthil Kumaran and Sujata Mohanty-2014)

Stem Cell Therapy in the Treatment of Neurological Diseases(Murat Kocaoglu, Mustafa Korucu, Serkan Civlan, Kevser Ozdemir, Mevci Ozdemir and Bayram Cırak-2014)

Stem Cells as Promising Therapeutic Options for Neurological Disorders (Jongman Yoo, Han-Soo Kim, and Dong-Youn Hwang-2013)

Canadian Institute of Health Research. Updated Guidelines for Human Pluripotent Stem Cell Research. 2010. [Last accessed on 2016 Mar 14].

Report: Stem cell applications in neurological practice, an expert group consensus appraisal (M. Gourie Devi,et al July 2016)

Harrison’s textbook of Internal medicine 19’th edi.