Chapter 11 Medical Biotechnology. Detecting and Diagnosing Human Disease Conditions Models of Human Disease Identify diseases and test therapies before

Chapter 11

Medical Biotechnology

Detecting and Diagnosing Human Disease Conditions

Models of Human Disease• Identify diseases and test therapies before

clinical trials in humans• Clinical trials: three phases

• Phase I: safety studies- safe dose and how to administer the dose (ADME)

• Phase II: few hundred patients for the purpose of testing effectiveness

• Phase III: effectiveness compared to other drugs –involve thousands of patients often with different backgrounds and stages of illness throughout the country

Models of Human Disease• Rat gene, ob, also found in humans therefore

homologous• Codes for a protein hormone called leptin if

missing leads to obesity• Found that treating obese children defected

in this gene with leptin decreases their weight


Models of Human Disease• Organism has 959 cells, 131 of them are

destined to go through apoptosis• Study programmed cell death in this organism• Programmed cell death important to correct

development of the fetus and improper cell death is implicated in: Alzheimers, Lou Gehrig’s, Huntington’s, Parkinson’s


Models of Human Disease• Heart attack mice

• Defect in cholesterol uptake


Detecting Genetic Diseases


Detecting Genetic Diseases• Testing for chromosome abnormalities and

defective genes• Amniocentesis (Test at 16 weeks - karyotype)• Chorionic villus sampling (Test at 8 to 10 weeks -

karyotype)



defective genes• Fluorescence in situ hybridization (FISH)

• Fluorescence probes that are specific for chromosomes and/or genes

• Spectral karotype



defective genes• RFLP (restriction fragment length polymorphisms)



defective genes• ASO allele-specific oligonucleotide analysis


Detecting Genetic Diseases• Single Nucleotide Polymorphisms (SNPs)

• One of the most common forms of genetic variation• Estimated that one SNP occurs approximately every 1,000-3,000

bp in the human genome • 99.9 percent of the DNA sequence will be exactly the same –>

80% of 0.1 percent variation will be SNPs• Most have no effect because they occur in non-protein coding

regions (introns)• 10 pharmaceuticals donated millions in a collaborative

partnership called the SNP Consortium


Detecting Genetic Diseases• Identifying sets of disease

genes by microarray analysis• Microarray created with known

diseased genes or SNPs• DNA from a patient is tagged

with fluorescent dyes and then hybridized to the chip

• Binding of a patient’s DNA to a gene sequence on the chip indicates that the person’s DNA has a particular mutation or SNP


Detecting Genetic Diseases• Protein Arrays

• Chips contain antibodies • Apply blood from a patient • Proteins from disease-causing organisms can be detected


The search for new medicines and drugs• Pharmacogenomics

• Different individuals with the same disease often respond differently to a drug treatment because of differences in gene expression.

http://learn.genetics.utah.edu/content/pharma/intro/

Medical Products and Applications of Biotechnology

Animation



http://learn.genetics.utah.edu/content/health/pharma/snips/

The search for new medicines and drugs• Oncogenes- genes that produce proteins that may

function as transcription factors and receptors for hormones and growth factors, as well as serve as enzymes involved in a wide variety of ways to change growth properties of cells that cause cancer

• Tumor Suppressor Genes – regulate oncogenes


The search for new medicines and drugs• Personalized Medicine

• BRCA1 or 2 – increases risk of developing breast cancer• But there are many other cases of breast cancer that do not

exhibit this mode of inheritance• They SHOULD be treated differently (i.e. different

chemotherapy!)


The search for new medicines and drugs• Improving techniques for drug delivery

• Factors that influence drug effectiveness• Drug solubility• Drug breakdown• Drug elimination

• Microspheres – tiny particles that can be filled with drugs


The search for new medicines and drugs• Nanotechnology and Nanomedicine

• nanosensors that can monitor blood pressure, hormone concentrations, unblock arteries, detect and eliminate cancer cells


Artificial Blood• Started testing of blood in 1980’s for HIV

• However it is still not tested in poor, developing countries

• There is a need for safe-blood• Possibilities: cell free solutions containing

molecules that can bind to and transport oxygen; or blood substitutes such as Hemopure that is made from the hemoglobin of cattle

• What does blood matching mean?


http://upload.wikimedia.org/wikipedia/commons/3/32/ABO_blood_type.svg

Vaccines and Therapeutic Antibodies• Vaccines stimulate immune system• Also hope that vaccination may be useful against

conditions such as Alzheimer’s disease or drug addiction• Using antibodies in some types of therapies:

Development of Monoclonal Antibodies


How is it done?

Gene Therapy

How is it done?• Delivering the payload: viral vectors for gene

delivery

Gene Therapy

Targets for Gene Therapy• Treating cystic fibrosis

• Defective cystic fibrosis transmembrane conductance regulator (CFTR)

• Normally it serves as a pump at the cell membrane to move electrically charged chloride atoms out of the cells

• If cells can’t move chloride out, they absorb water trying to dilute the chloride in the cell

• This leads to the production of THICK sticky mucus

Gene Therapy

Challenges Facing Gene Therapy• Reaction to the vector, an adenovirus, led to

the death of Jesse Gelsinger• It raised more questions than answers:• Can gene expression be controlled in the

patient?• How long will the therapy last?• What is the best vector?

Gene Therapy

Animation

http://learn.genetics.utah.edu/content/tech/genetherapy/cysticfibrosis/build.html

Growing cells and tissues that can be used to replace or repair defective tissues and organs

Regenerative Medicine

Cells and Tissue Transplantation• 50,000 Americans are diagnosed with Parkinson’s

annually• Caused by a loss of dopamine-producing cells deep inside

the brain• Leads to tremors, weakness, poor balance, loss of dexterity,

muscle rigidity, reduced sense of smell, inability to swallow and speech problems

• After 4 to 10 years the drugs become ineffective leading to a poor quality of life for the patient


Cells and Tissue Transplantation• Fetal tissue grafts

• The basic idea is to introduce fetal neurons which can establish connection with other neurons

• Over 100 patients have received such transplants-shown some recovery


Cells and Tissue Transplantation• Organ transplantation

• 8 million surgeries are performed each year and about 4000 people die waiting

• Autograft – transplanting a patient’s own tissue from one region of the body to another- ex. Vein from leg used in coronary bypass-organ transplants are between individuals and so must be checked for compatibility• Histocompatibility complex - >70 genes which produce

tissue typing proteins (must match!)• There are many different types of MHC proteins (one

group is called human leukocyte antigens or HLAs)- have been using immunosuppressive drugs but there are problems.


Cells and Tissue Transplantation• Organ transplantation

• Xenotransplantation – transfer between species (pig to human)• University of Missouri scientists have produced cloned, knockout

pigs that lack a gene called GGTA1 (or 1,3 galactosyltransferase) • The gene normally codes for a sugar that would be recognized as

foreign by humans


Cells and Tissue Transplantation• Cellular therapeutics

• Involves using cells to replace defective tissues to deliver important biological molecules

• Encapsulate living cells into tiny plastic beads (biocapsules)• Capsule protects the cells from rejection but yet allows

chemicals to diffuse out• Could be used in Type 1 diabetes therapy


Tissue Engineering• Replacement of

tissues and organs by growing them in culture

• So far skin grafts have been successfully engineered


Tissue Engineering• The telomere story

• Usually 8 to 12,000 base pair units of the the repeating sequence 5’-TTAGGG-3’. (think of plastic tabs at the end of your shoe laces-prevents unraveling)

• A cell’s lifespan is affected in part by telomeres –each time a cell divides, telomeres shorten slightly-which leads to senescence! (aged cells!)

• Telomerase repairs telomere length by adding DNA nucleotides to cap the telomere after each round of cell division


Stem Cell Technologies• The CDC estimates hat 3,000

Americans die every day from diseases that may one day potentially be treated by stem cell technologies

• What are stem cells?


Known asPluripotent!

Stem Cell Technologies• What are stem cells?

• Two major properties:• ES cells can self-renew indefinitely to produce more stem

cells• Under the proper growth conditions, ES cells can

differentiate into a variety of mature cells with specialized functions• Human ES cells avoid senescene in part because they

express high levels of telomerase!


Stem Cell Technologies• Adult-derived stem cells do everything

embryonic stem cells can do and remove the ethical issue of destroying embryos.

• Amniotic-fluid derived stem cells• Reprogramming somatic cells


Stem Cell Technologies• Potential Applications of Stem Cells


Stem Cell Technologies• Questions that need to be answered:

• Is there an “ultimate” adult stem cell that could turn into every tissue in the body?

• Why do stem cells self-renew and maintain an undifferentiated state?

• What factors trigger division of stem cells?• What are the growth signals (chemical, genetic,

environmental) that influence the differentiation of stem cells?

• What factors affect the integration of new tissues and cells into existing organs?


Cloning• Therapeutic Cloning and Reproductive Cloning


How was this done?

Human Genome Project

Revealed disease genes on all human chromosomes

Human Genome Project

Documents

Chapter 11 Medical Biotechnology. Detecting and Diagnosing Human Disease Conditions Models of Human Disease Identify diseases and test therapies before