Cellular Therapies Flashcards
what is the clinical need for cellular therapies?
> 130 million individuals globally
Chronic/degenerative/ acute diseases
NO TREATMENTS
this presents significant challenges for the health care systems and for patients/families, suffering, social and economic losses
what potential do cellular therapies have?
potential to provide curative treatments for many diseases with unmet needs
define cellular therapy
Administration of live human cells to a patient for repair/replacement/ regeneration of damaged tissue and/or cells
what kinds disorder are cellular therapies being invistagted to treat?
Baldness Brain injury - stroke, MS, cerebral palsy, parkisons, AD Blindness Hearing Loss Spinal Cord Injury Bone fractures CF Heart disease Liver Failure Diabetes Cancer
what therapies are currently licenced?
ChondroCelect- repair of knee cartilage (
MACI - repair of knee cartilage
Provenge - Prostat cancer
Holoclar - cornea epithelium replacement
Stimvelis - adenosine deaminase deficiency
Zalmoxis - haematological cancers
what are the aims of cell and gene therapy catapult?
Bridge the gap between business, academia, research and government
Accelerate the growth of cell therapy industry in UK
what are the 2 classifications of cell therapy?
Autologous (patients own cells)
Allogenic (donor cells)
explain autologous cell therapy
Immunological compatibility
No HLA matching/immunosuppression required
Resembles an individualised procedure
Heterogeneous - donor variability
Imprecisely characterised
Stringent traceable logistics: Collection Transport Manufacture/manipulation Administration back to patient
Manual process- high production work load
Expensive
explain allogenic cell therapy
Risks of: immune response/rejection/ graft-versus-host disease Immunosuppression May ↓ product function, other risks
Standardised product- guaranteed dose
Cell bank
Simplified supply: off-the-shelf product
Automated process- less labour intensive
Lower costs
what are the cell types under clinical development?
1) stem cells
2) terminally differentiated cells
3) genetically modified cells
what are stem cells?
single cells with unique characteristics such as:
replicate itself to maintain stem cell pool
retain its undiff state
can diff into many cell types by switching on specific genes in response to external/internal chemical signals
replace dead/damaged cells throughout life
what is the stem cell hierarchy?
classified according to potential to develop into other cell types (plasticity:
1)totipotent - most versatile, produced in first few cell division in embryonic development, differentiate into any adult cell type, give rise to entire organism
2) pluripotent - originate from 5 day old embryo, can differentiate into any adult cell types
3) mulitpotent ie. blood stem cells and other stem cells (muscle, nerve, bone)
how are stem cells relevant to therapies?
ESC (pluripotent) - grown in lab from cells of early embryo
iPSC (pluripotent) - made from adult specialised using lab technique
adult/somatic stem cell (multipotent) - found throuhghout body, found in children and adults
what are embryonic stem cells?
derived from inner cell mass of 5 day old embryo
ability to differentiate into cell types of three primary germ layers
equates to >200 diff cell types in adult human
ethical dilemma of using ESC?
derived from embryos produced via IVF
donated for research with informed consent of donors
balance of preventing/alleviating suffering vs respecting the value of life
research is tightly regulated, illegal in austria, denmark, france, germany and ireland
used in UK strictly controlled by HEFEA
what disorders are ESC being used for in trials currently?
age-related macular degeneration - retinal pigment epithelium
parkinsons disease - a9 dopaminergic neuron
spinal cord injury-oligodendrocyte progenitor
diabetes-pancreatic islet b-cell progenitor
MI- cardiomyocytes
what are iPSCs?
produced by reprogramming terminally differentiated cells:
1) terminally diff cells removed from patient
2) transduced with stemm cell associated genes using viral vectors
3) cells reprogrammed
4) directed to differentiate
iPSCs behave like embryonic stem cells-can differentiate into a variety of cells types
how can iPSC be used therapeutically?
1) patient skin biposy or other tissue
2) cells cultured in vivo
3) cells reprogrammed back to expandable iPSC
4) Directed to differentiate into clinically useful cell types
5) autologous transfer to treat original patient
6) treat individual with:disease, injury, inherited disorder or age related tissue degeration
what are the pros of iPSCs?
Eliminate ethical issues of ESC use Derived from patient’s own cells: ↓ immuno-rejection Ability to differentiate → any cell type
Unlimited proliferation capacity Readily accessible (skin, blood cells) Opportunities for personalised treatments Potential for preservation (cell banks) Possibilities of gene correction therapies
what are the cons of iPSCs?
Low rate of reprogramming
Cells from patient with genetic disease still carry same defective gene
High level of genetic instability in culture
Pluripotency genes (c-Myc) is oncogene- overexpression could cause cancer
Retroviral vectors insert pluripotency genes randomly → genome = undesirable mutations
what are the challenges to overcome before iPSC suitable for clinical use?
Regulatory requirement: cells with stable/consistent characteristics.
2014: Japan, patient administered autologous iPSC-derived retinal pigment epithelium cells for treatment of age-related macular degeneration
2015: trial halted - mutations identified in iPSCs produced for second patient- arose during reprogramming process
Concern: transplantation of genetically unstable cells → uncontrolled cell growth/tumour formation
what are adult or somatic stem cells?
multipotent: limited to differentiating into specialised cell types within tissue of origin
found in many organs and tissues: stem cell niches
remain undifferntiated until activated: maintan tissue homeostasis, disease, tissue injury.
adult stem cells in current clinical practice
haematopoietic stem cell translplantation - most frequently used cell therapy. Obtained from peripheral blood, bone marrow and umbilical cord blood
SC, diff into all the types of blood cell.
SC can be autologous or allogenic
treatment of: malignant/non-malignant blood disorders
genetic disorders of immune system
what are mesenchymal cells (MSC)?
example of adult stem cell, derived from: bone marrow, adipose tissue, placenta and umbilical cord, peripheral blood.
Capable of:
differentiating into cell types of mesenchymal tissues
transdifferentiating into non-mesenchymal cells (neurons, epithelial)
what is the therapeutic potential of MSC?
Comes from their ability to: secrete solutble factors crucial for cell survival and proliferation
modulate immune response
differentiate into various cell types
transdifferentiate-non mesoderm
migrate to sites of injurt in response to cell signals
MSC clinical trials
Globally: 463 registered clinical trials
296 employ autologous MSC
Cover wide range of therapeutic applications: Cardiovascular Autoimmune Osteoarthritis Liver disorders GvHD
Major sources of MSC in clinical trials:
Bone marrow
Umbilical cord
Adipose tissue
No approved treatments using MSC
how can we exploit use of adult stem cells?
Commercial companies provide services to isolate/store stem cells
UK: Future Health Biobank, Cell4life, Precious cells
Biological insurance: individual/child/ family member develops a disease in the future treatable by stem cells
One off charge (+maintenance fees)
Cells sources: umbilical cord placenta blood adipose tissues dental pulp from child's teeth
what are terminally differentiated cells?
Specialized cells unable to proliferate and have reached the final stage of development
what current practice involve TDCs?
donor platelet transfusions
platelet deficiency due:
disease
treatment related- chemotherapy
life threatening bleeding - injur injury or trauma
autologous platelet rich plasma therapy
what is platelet rich plasma therapy?
platelets rich source of growth factors which stimulate development soft tissue/bone cells
procedure claims to initiate faster healing response
blood collected, centrifuged to seperte blood, plateley rich plasma collected, injected into injured area
used in treatment of ortho conditions: Osteoarthritis Tendonitis Tendon tears Nerve injury Professional athletes with muscle and ligament injuries (Tiger Woods
what other practice involves TDCs?
red cell transfusions
treat anaemia:
heavy blood loss
bone marrow not producing enough red cells (chemo, leukaemia/sickle cell)
autologous erthyrocyte encapuslated enzyme replacement therapy
what is autologous erythrocyte encapuslated enzyme replacement therapy?
Under clinical development at SGUL for treatment of diseases due to inherited enzyme deficiencies
1) deficient enzyme encapsulated in patients erythrocytes in vitro
2) intravenously administered to the patient
3) permit elimination of pathological plasma metabolites:
pathologically elevated plasma metabolite permeate cell membrane
encapsulated enzyme catalyses substrate–> normal product
normal product exits cell to enter usual metabolic pathway
this is applicable to disorders where pathologically high metabolite permeate erythrocyte membrane
what are the benefits of a therapeutic approach?
majority licesence enzyme replacement therapies (ERT)
High enzyme activity half-life:
- short plasma half-life, frequent infusions:maintain therapeutic effective levels
low immunogenic reactions and production of anti-enzyme antibodies:
anti-enzyme antibody production leads to loss of therapeutic efficacy
allergic reactions
what is the encapsulating process?
1) erythrocytes + exogenous enzyme undergo hypo-osmotic dialysis
2) erythrocytes swell; formation of pores in membran
3) exogenous enzyme enters cell and iso-osmotic dialysis occurs.
4) erthyrocytes reseal, encapsulating therapeutic agent
what are the applications for erythrocyte mediated enzyme replacement therapy?
treatment two autosomal recessive metabolic disorders:
1)Mitochondrial NeuroGastroIntestinal Encephalomyopathy (MNGIE)
Product: erythrocyte encapsulated thymidine phophorylase (EE-TP)
2) Adenosine deaminase deficiency
product: erythrocyte encapsulated adenosine deaminase (EE-ADA)
explain the metabolic defect in MNGIE
mutatuon in the nuclear gene (TYMP) which encodes for thymidine phosphorylase (TP)
mitochondiral deoxynucleotide pool imbalance leading to:
1) increased [plasma] of thymidine and deoxyuridine
2) impaired replication/repair leading to multiple deletions, point mutations and depletion
Ultimarley loss of mitochondiral respiratory chain function.
what are the symptoms of MNGIE?
Mainly effects GI and nervous system.
GI symptoms: Severe gastrointestinal dysmotility Psuedo-obstruction Nausea/vomiting Chronic abdominal pain Premature satiety LEADS TO: Malabsorption Bacterial over-growth Intestinal perforation Loss of muscle mass
Neuro symptoms:
Leukoencephalopathy
Demyelination nerve fibres
Initially patchy
Ocular symptoms
Ptosis
Loss of vision
Peripheral neuropathy
Numbness
Muscle weakness
Hearing loss
patients die avg age 37 combo of nut and neuromusc failure
clinical experience with EE-TP in MNGIE
Bax et al (2013) demonstrated:
Clinical improvements in sensory ataxia (balance and gait) & fine finger functioning
Increase in body weight
Walk longer distances, climb stairs without assistance, tie shoe laces
Returned to public performances as guitar player in a band
Previously reported numbness in hands/feet resolved
what types of genetically modified cells are under clinical investigation?
1) gene modified autologous stem cell therapies
2) engineered T-cell therapies
what are gene modified autologous stem cell therapies?
autologous stem cells collected from patient and genetically corrected prior to reinfusion
eg: HSC-directed gene therapy
HSCs are multipotent, capable of generating entire epctrum of blood/lymphoid cells
suitable target therapies for: haematological malignancies
iherited blood disorders
steps of gene modified autologoues stem cell therapies
approved 2016: treatment of inherited severe combined immunodeficiency disease: adenosine deaminase deficiency
1)HSCs isolated from bone marrow
2)CD34+ cells expanded in culture
Transduces with retroviral vector expressing fucntional copy of defective gene (adenosine deaminase)
3) endogenous bone marrow progenitors eliminated to favour engraftment
Modified stem cells infused.
Gene-corrected stem cells reconsititute lymphoid lineages/restore immune function
what are enginereed t cell therapies?
tumour cells often recognised as ‘self’ - prevents T cells from recognizing tumour proteins
solution: genetically alter T-cells to create recognition receptors unique to patients tumour
altered t cells expanded in culture and infused into patient which seek out/destroy tumour cells
two approached:
t-cell receptor therapies (TCR)
chimeric antigen receptor (CAR-T) therapies
steps of TCR therapy
1) peripheral blood lymphocytes removed from patient
2) cells transduced with viral vector containing contruct encoding for tumour reactive TCR
Expanded in culture
Infused into patient
3) Infused cells express modified TCR on surface
4) recognise tumour-specific proteins on the inside of cell through encountering tumour antigen peptide processed and presented on cell surface
5)tumour destruction
what is CAR-T?
chimeric=composed of parts from two or more different sources
CAR= artificial receptor that links:
1)antibody molecule:polypeptide sequences of light and heavy chain from antibody recognises target proteins expressed on cancer cell surface
and
2)t-cell signalling machinery of t-cell receptor:
on binding to target- clonal expansion, secretion of cytokines to recruit immune system, destruction of tumour cell
steps of CAR-T therapy
1) peripheral blood lympocytes removed from patient
2)cells transduced with viral vector containing CAR construct
expanded in culture
infudes into patient
3)expressed CAR recognises external antigen leading to death of targeted cancer cells
what are the challenges faceing cell therapy commercialisation?
Turning cells into effective/safe/ affordable therapies poses many challenges:
