AVROBIO Gene Therapy Education

AVROBIO Gene Therapy Reference

05 Resources

Section 2

Glossary

Gene therapy uses many specialized terms, words, and concepts that may be new to you. Learning what each term or word means can help you better understand these new concepts. Check out the definitions below for many of the terms and words that appear throughout the website.

A

Acquired mutation (acquired variant)

a genetic change that occurs in one cell after the conception of an individual. This genetic change is passed on to each of the cells that descend from that one cell.1

Adeno-associated viral (AAV) vector

a tool used in gene therapy to deliver genetic material into a cell. AAV vectors deliver their payload to the nucleus and the genetic contents enter.2,3

Adenoviral (Ad) vector

a tool used in gene therapy to deliver genetic material into a cell.4

Adverse event (AE)

any medical issue associated with a patient or participant who is receiving a treatment in a clinical trial or who is receiving the treatment once it is approved for public use. Adverse events are not always caused by the treatment or medicine in a trial.2

Allele

different forms of the same gene at a particular location on a chromosome. For example, different alleles may produce different versions of the same protein.5

Amino acids

organic compounds that serve as building blocks that combine to form proteins.6

Apheresis

the process of passing a person’s blood through a machine that separates components like stem cells, plasma, platelets and white blood cells and then returns the rest of the blood directly back into the person.2 Apheresis is the most common way to collect the target cells that are processed (see transduction) for lentiviral gene therapy.

Autosomal dominant inheritance (dominant trait)

Dominant refers to the relationship between two versions of a gene. Individuals receive two versions of each gene, known as alleles, from each parent. If the alleles of a gene are different, one allele will be expressed; it is the dominant gene. The effect of the other allele, called recessive, is masked.7

Autosomal recessive inheritance (recessive trait)

Recessive is a quality found in the relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele will be expressed, while the effect of the other allele, called recessive, is masked. In the case of a recessive genetic disorder, an individual must inherit two copies of the mutated allele in order for the disease to be present.7

Autosome

any non-sex chromosome, as opposed to the sex chromosomes. Individuals typically have 22 pairs of autosomes (numbered 1-22) and one pair of sex chromosomes (called X and Y).7

B

Bone marrow

the soft, sponge-like tissue in the center of most bones. Bone marrow produces white blood cells, red blood cells, and platelets.8

C

Capsid

the outer protein shell, or coat, of a virus or vector that protects its genetic material and allows it access to the target tissues or cells.1,2

Cardiac

related to the heart.8

CAR-T cell therapy

an immuno-oncology therapy in which T-cells are genetically modified in a manufacturing facility and infused into the patient and designed to eradicate cancer cells.10

CD34+ cell

a type of stem cell or progenitor cell found in the bone marrow, umbilical cord, and blood. When these cells divide, they may differentiate into many different types of blood cells.11

Cell

the basic building block of all living things.5

Cell therapy

the use of cells as therapy. There are many types of cell therapies including genetically modified and non-modified.12

Central nervous system (CNS)

the brain and spinal cord.8

Chemistry, manufacturing, and controls (CMC)

(part of new pharmaceutical product applications to the US Food and Drug Administration). To appropriately manufacture a pharmaceutical or biologic, CMC are the specific manufacturing processes, product characteristics, and product testing that must be defined to ensure that the product is safe, effective, and consistent between batches.13

Chromosome

a structure found in the cell nucleus made up of DNA and proteins which are organized into genes. All human cells contain two pairs of 23 chromosomes (one from each parent for 46 in total), except for mature sperm and eggs, which contain only one set of 23 chromosomes.5,8

Chronic

a condition that typically lasts a long time.14

Clinical

medical work involving patients.8

Clinical trial

a research study that includes human volunteers and is designed to answer specific questions about a disease, a new therapy, or other ways of using an existing treatment. Clinical trials can help determine whether new drugs or treatments are safe and effective.15

Conditioning

a process used to prepare the body to receive stem cells. Conditioning for lentiviral gene therapy typically utilizes a medicine that helps to make room in the bone marrow for the genetically modified stem cells to engraft (permanently take hold).8

Cryopreservation

the process of freezing and storing cell tissue at very low temperatures to keep the tissue healthy.2

D

Daughter cells

the two cells formed when a parent cell divides. Daughter cells contain the same number and type of chromosomes as the parent cell and are therefore genetically identical to the parent cell.15

Disease mechanism

the cause(s) and path of a disease. Defects in specific genes are the mechanisms by which genetic disorders develop.17

Disease screening (for genetic diseases)

the process of determining whether someone is at risk (or carry a disease-associated variant) for a specific inherited disease. A genetic test is an example of a disease screening procedure.8

DNA

deoxyribonucleic acid, the double helix or ladder-like structure that holds a cell’s genetic information. DNA (also called genetic or hereditary material) is made up of four coding elements (nucleic acids) called
adenine (A), guanine (G), cytosine (C), and thymine (T).8,15 DNA encodes instructions for making proteins.

Drug product

a finished dosage form of a therapy. For example, genetically modified transduced cells.18

Durability

the ability of a therapy to remain clinically effective over time.19

E

Efficacy

the ability of a medicine, treatment, or procedure to produce a beneficial effect for a patient.8

Engraftment

the process of genetically modified stem cells permanently attaching or taking hold in the bone marrow.2

Enzyme

a protein that speeds up (catalyzes) chemical reactions in the body, specifically reactions that accelerate the build-up or breakdown of biological molecules.8

Ex vivo

occurring outside of a living organism.2

G

Gene

the basic unit of heredity. Made of DNA, genes act as a blueprint for making specific proteins, including enzymes, in the body.8 People have approximately 20,000 genes.20

Gene addition or augmentation

inserting a therapeutic gene into a person’s DNA to treat a genetic condition.21 A gene addition is not inherited or passed down.

Gene editing

an investigational technique that changes the DNA by inserting, deleting, or modifying a gene. Sometimes referred to as genome editing or genome engineering.5

Gene expression

the process by which the genes (instructions) coded in a person’s DNA are converted into a functional product, such as a protein.5

Genetically modified stem cell

a stem cell with altered DNA, often designed to treat a genetic condition.22

Gene silencing

switching off the gene’s ability to make a functional protein.23,24

Gene therapy

introduction of exogenous (from outside a cell or an organism) genetic material into cells to cure or improve a genetic disorder.5

Genetic condition

a disorder or disease caused by an abnormality in a person’s genome.25

Genetic material (genetic information)

hereditary material found in cells. See DNA or RNA.

Gene mutation

a change in DNA that can alter the way a gene works. This change can cause a non-working protein to be produced or prevent a protein from being made at all.15

Genome

all inherited genetic material of an organism.2

Genotype

a person’s collection of genes associated with a given inherited trait.7

Germ cell

a reproductive cell in the body: egg and sperm. Also called germline cell.5

Germline therapy

introducing new DNA into germ cells to correct hereditary genetic changes that cause disease.2 Due to ethical concerns, germline therapy is not currently allowed and clinical trials of gene therapy to date only involve somatic cells.

Good manufacturing practices (GMP)

is a system for ensuring that products are consistently produced and controlled according to quality standards. These practices are designed to minimize the risks involved in any pharmaceutical production that cannot be eliminated through testing the final product.26

Graft rejection

when bone marrow from a donor (allogeneic stem cell transplant) is infused and then rejected by the person receiving the donation.27

Graft-versus-host disease

an adverse reaction to an allogeneic stem cell transplant in which the donor’s cells attack the patient’s own cells.2

H

Hematopoietic stem cell (blood stem cell)

a stem cell that can divide to produce daughter cells. These daughter cells can differentiate to become different types of blood cells, such as red blood cells, white blood cells, and platelets.8

Hematopoietic stem cell gene therapy (HSC gene therapy)

a technique in which a person’s hematopoietic stem cells (HSCs) are genetically modified ex vivo (outside the body) by adding a copy of the functional gene that codes for a therapeutic protein. Upon returning the person’s own genetically modified stem cells to their body, these cells divide and generate new cells, all of which express the therapeutic protein. HSC gene therapy can use lentiviral (LV) vectors to carry the functional gene into a person’s own stem cells, allowing it to integrate into the patient’s stem cells, with the goal of durably expressing the therapeutic protein throughout the body, including the central nervous system.34-36

Hematopoietic stem cell transplant (HSCT)

a medical procedure in which hematopoietic stem cells are obtained and given to a person.15 There are two types of hematopoietic stem cell transplants – autologous and allogeneic:

  • Allogeneic hematopoietic stem cell transplant (allogeneic HSCT or alloHSCT)
    a medical procedure in which cells or tissues are obtained from one person (donor) and given to another person (recipient).28
  • Autologous hematopoietic stem cell transplant (autologous HSCT or autoHSCT)
    a medical procedure in which the patient receives through intravenous infusion their own blood stem cells or bone marrow that were previously collected.29 In autologous gene therapy, a patient’s cells are obtained, genetically modified, and returned to the same person.

Hereditary material

see DNA.

Heredity

the transmission (inheritance) of genetic material from parents to child.30

I

Immunogenicity (allergic reaction)

the phenomenon in which a person’s body recognizes a substance as foreign and then mounts an immune response to that substance.16,31

Immunosuppressive medication

a medication typically used in donor transplant procedures to keep a person from rejecting a donor’s stem cells or organ.8 This class of medications tends to reduce the body’s ability to respond to an infection (mount an immune response).

Inherited

passed down from parents to child.32

In vitro

outside of the body, for example in a test tube.2,8

In vivo

in the body.2

Integrating vector

a viral vector that inserts a piece of genetic material into the chromosomes for the purpose of gene therapy. Being integrated into the chromosomes means that the genetic material will be passed on to daughter cells when they divide.33

Intravenous (IV) infusion

a process by which medicines or other substances are administered through a needle or tube inserted into a vein.8

Investigational

a treatment approved by a federal agency to be tested in humans but not yet approved to be prescribed as a treatment outside of clinical trials.8

L

Lentiviral gene therapy

an approach in which hematopoietic stem cells (HSCs) are genetically modified ex vivo. Lentiviral gene therapy has the ability to impact disease via bone marrow cells, nucleated blood cells (i.e., those with a nucleus), and tissue resident macrophages (i.e., those that live long-term in various organs and tissues), which include microglia in the central nervous system (CNS).34-36

Lentiviral (LV) vector

a tool used in gene therapy to deliver genetic material into a cell. LV vectors are designed to permanently insert genetic material into the host’s cells and carry a large amount of genetic material.37,38

Lifespan (cells)

the period of time that cells live. Lifespan can vary dramatically depending on the type of cell. For example, the lifespan of red blood cells is about 120 days while the lifespan of neutrophils (a type of white blood cell) is less than one day.34

Lymphocyte

a white blood cell (leukocyte) that triggers immune responses to defend the body against infections and other types of foreign particles. The two main types of lymphocytes are B cells, which make antibodies that bind and help clear bacteria and toxins; and T cells, which help remove body cells that have been taken over by viruses or have become cancerous.39

Lysosome

one or more compartments in a cell that help recycle materials, including large molecules.8,40

M

Macrophage

a type of white blood cell that finds and digests foreign material.41

Messenger RNA (mRNA)

an intermediate molecule responsible for the translation of information contained in DNA to produce proteins.2,5,15

Metabolic disorder

a condition that disrupts normal metabolism and is usually caused by a missing or non-working enzyme.8

Metabolism

the body’s process for breaking down substances (e.g., food or medicines) to create energy and the materials cells and organisms need to grow, reproduce, and stay healthy.8

Metabolite

a product of metabolism.8

Microglia

a cell type with the brain and spinal cord, similar to macrophages in other tissues. Microglia play a primary role in the immunological response of the brain and spinal cord.42

Mobilization in gene therapy (also called stem cell mobilization)

the use of medicines to move stem cells from the bone marrow into the blood. The stem cells can then be collected, using apheresis, and stored for later use during a stem cell transplant.8

Monogenic disorder

a disease caused by change(s) in a single gene.43

Mutation (also called gene variant)

a permanent change in the DNA sequence of a cell. These changes can be harmful, beneficial, or have no effect.8

Myeloablative therapy

a treatment used in ex vivo gene therapy to ablate (remove) cells in the bone marrow to make space for the genetically modified stem cells that are carrying the functional gene (infused drug product).44

N

Neurologic

relating to the nerves or the nervous system.8

Neuropathic

relating to neuropathy.

Neuropathy

any nerve disease or malfunction.45

Nucleus

the control center of a cell, which contains a person’s genes organized into chromosomes.8,46

P

Pathophysiology

altered function in an individual or an organ due to a disease.47

Peripheral blood cells

all the red and white blood cells that circulate throughout the body.48

Peripheral nervous system

parts of the nervous system outside the brain and spinal cord.49

Phenotype

observable characteristics or traits (like blood type or eye color) that come from a person’s genotype and/or environment.15

Plasmid

a small, often circular DNA molecule typically found in bacteria.7 Plasmids are used to manufacture gene therapy vectors.

Platelet

an element in the blood that helps with clotting.50

Polygenic disorder

a disease caused by changes in more than one gene.51

Potency

a measure of how much a product (such as gene therapy) affects a living organism, tissue, or cell.2

Preclinical study

a study, typically in laboratory animals, that aims to demonstrate proof of concept, support efficacy, and/or measure safety of a treatment or therapy. A preclinical study may be necessary before the treatment or therapy is allowed to be tested in people.2,5,15

Progenitor cell

a cell that is descended from a stem cell that can further differentiate into a mature, specialized cell.52

Protein

a large complex molecule made up of amino acids. Proteins perform a wide variety of activities in the body.5 Enzymes are a type of protein.

R

Red blood cells

the blood cells that carry oxygen.53

Retroviral vector

a genetic delivery tool that contains RNA. Once inside the cell, the RNA is turned into DNA, which then inserts itself into the host cell’s own DNA.15 These delivery vehicles have been precisely crafted by scientists for use in gene therapy.

RNA

ribonucleic acid, a molecule similar to DNA. There are a few types of RNA molecules. One of the functions of RNA is to convert, or translate, the genetic code of DNA into structural proteins.8,14

S

Serious adverse event (SAE)

a medical problem associated with a therapy that results in hospitalization, death, or life-threatening, disabling, or incapacitating illness.2

Sex chromosomes

chromosomes involved in determining the sex of an individual. Most individuals have two sex chromosomes. Females typically have two X chromosomes in their cells, while males will typically have one X chromosome and one Y chromosome in their cells.7

Sex-linked inheritance

a genetic trait or condition that is passed down on either the X or Y chromosomes, known as the sex chromosomes.7

Shelf-life

the stability of a product during storage, or the amount of time a product can be stored.54

Somatic cell

a cell with two copies of chromosomes. Most cells in the body are somatic cells. By contrast, mature reproductive or germ cells have half the number of chromosomes and are not somatic cells.15

Specialized cell

a cell that is specifically designed to perform certain jobs in the body. Examples include neurons, which carry messages in the brain, and muscle cells, which make movement possible.55

Stem cell

a cell that can self-renew indefinitely and can turn into any other type of cell in the body (differentiate into a specialized cell).5,56

Substrate

a material that is acted upon by an enzyme.57

T

T-cell

a type of white blood cell that is part of the body’s immune response to certain pathogens (for example, viruses).5

Therapeutic gene (transgene)

genetic material intended to treat a genetic disorder at the cellular level.5,58 ­­­­

Tissue

a group or layer of similar specialized cells that work together to perform a specific job.2

Transduction

the process by which a viral vector introduces therapeutic genetic material into a cell.2

Translation

the process of converting the sequence of messenger RNA to a sequence of amino acids during protein production.2

V

Vector

a delivery system used to introduce genetic material into the nucleus of a cell.2,5

Viral vector

a delivery tool. See adeno-associated viral (AAV) vector or lentiviral (LV) vector.

Vector copy number

the number of copies of the therapeutic gene (transgene) in a cell.59

W

White blood cells

cells the body makes to help fight infections.8

References

  1. Genes and cancer: changes in genes. American Cancer Society; 2014. https://www.cancer.org/cancer/cancer-causes/genetics/genes-and-cancer/gene-changes.html. Accessed December 23, 2021.
  2. The Glossary for Cell & Gene Therapy and Regenerative Medicine, 4th Regen Med. 2018;13(8 Suppl 1):1-122. https://www.regmednet.com/the-glossary-for-cell-gene-therapy-and-regenerative-medicine-2018/. Accessed December 23, 2021.
  3. Adeno-associated viral vectors. GeneTherapyNet.com; 2021. https://www.genetherapynet.com/16-viruses-/adeno-associated-viral-vectors.html. Accessed December 23, 2021.
  4. Wold WS, Toth K. Adenovirus vectors for gene therapy, vaccination and cancer gene therapy. Curr Gene Ther. 2013;13(6):421-433. [PubMed]
  5. Gene and Cell Therapy Glossary. European Society of Gene & Cell Therapy; 2021. https://www.esgct.eu/Home/Public–Patients/Gene–Cell-Therapy-glossary.aspx. Accessed December 23, 2021.
  6. Amino acids. MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine, National Institutes of Health; 2021. https://medlineplus.gov/ency/article/002222.htm. Accessed December 23, 2021.
  7. National Human Genome Research Institute. Talking glossary of genetic terms; 2021. https://www.genome.gov/genetics-glossary. Accessed December 23, 2021.
  8. NCI Dictionary of Cancer Terms. U.S. Department of Health and Human Services, National Institutes of Health, National Cancer Institute; 2022. https://www.cancer.gov/publications/dictionaries/cancer-terms/. Accessed January 3, 2020.
  9. Marks JW. Medical definition of capsid. MedicineNet; 2021. https://www.medicinenet.com/capsid/definition.htm. Accessed December 23, 2021.
  10. CAR T-cell therapy. National Cancer Institute; 2022. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/car-t-cell-therapy. Accessed January 3, 2022.
  11. AbuSamra DB, Aleisa FA, Al-Amoodi AS, et al. Not just a marker: CD34 on human hematopoietic stem/progenitor cells dominates vascular selectin binding along with CD44. Blood Adv. 2017;26(1):2799-2816. [PubMed]
  12. Facts about cellular therapies. Association for the Advancement of Blood & Biotherapies; 2021. https://www.aabb.org/news-resources/resources/cellular-therapies/facts-about-cellular-therapies. Accessed December 23, 2021.
  13. Chemistry, manufacturing, and controls (CMC) information for human gene therapy investigational new drug applications (INDs): guidance for industry. U.S. Department of Health and Human Services, Food and Drug Administration, Center for Biologics Evaluation and Research; 2020. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/chemistry-manufacturing-and-control-cmc-information-human-gene-therapy-investigational-new-drug. Accessed December 23, 2021.
  14. Davis CP. Medical definition of chronic. MedicineNet; 2021. https://www.medicinenet.com/chronic/definition.htm. Accessed December 23, 2021.
  15. American Society of Gene & Cell Therapy. Glossary; 2021. asgct.org/education/more-resources/glossary. Accessed December 23, 2021.
  16. The Free Dictionary.: thefreedictionary.com/. Accessed December 23, 2021.
  17. Drug development tutorial: disease mechanism. Alzforum, FBRI LLC; 2021. https://www.alzforum.org/drug-development-tutorial/target-discovery/disease-mechanism. Accessed December 23, 2021.
  18. S. Food & Drug Administration. Drugs@FDA Glossary of Terms; 2017. https://www.fda.gov/drugs/drug-approvals-and-databases/drugsfda-glossary-terms#D. Accessed December 23, 2021.
  19. Kalra S, Kamaruddin NA, Visvanathan J, et al. Defining disease progression and drug durability in type 2 diabetes mellitus. Eur Endocrinol. 2019;15(2):67–69. doi: 10.17925/EE.2019.15.2.67. [PubMed]
  20. Pray LA. Eukaryotic genome complexity. Nature Ed. 2008;1(1):96. https://www.nature.com/scitable/topicpage/eukaryotic-genome-complexity-437/. Accessed January 3, 2022.
  21. The potential of gene therapy. STAT; 2018. https://www.statnews.com/sponsor/2018/11/20/the-potential-of-gene-therapy/. Accessed December 22, 2021.
  22. Phillips MI, Tank YL. Genetic modification of stem cells for transplantation. Adv Drug Deliv Rev. 2008;60(2):160-172. [PubMed]
  23. National Center for Biotechnology Information, U.S. National Library of Medicine. Gene silencing. 2017. ncbi.nlm.nih.gov/probe/docs/applsilencing/. Accessed December 23, 2021.
  24. Redberry G. Gene Silencing: New Research. Nova Science Publishers; 2006. ISBN 9781594548321.
  25. Marks JW. Medical definition of genetic disease. MedicineNet; 2021. https://www.medicinenet.com/genetic_disease/definition.htm. Accessed December 23, 2021.
  26. S. Food & Drug Administration. Facts about the Current Good Manufacturing Practices (CGMPs). 2021. https://www.fda.gov/drugs/pharmaceutical-quality-resources/facts-about-current-good-manufacturing-practices-cgmps. Accessed December 23, 2021.
  27. Mattson J, Ringden O, Storb R. Graft failure after allogeneic hematopoietic cell transplantation. Biol Blood Marrow Transplant. 2008;14(suppl 1):165-170.
  28. Mayo Clinic. Bone marrow transplant. Allogeneic stem cell transplant; 2021. mayoclinic.org/tests-procedures/allogeneic-stem-cell-transplant/pyc-20384863. Accessed December 23, 2021.
  29. Mayo Clinic. Bone marrow transplant. Autologous stem cell transplant; 2021. mayoclinic.org/tests-procedures/autologous-stem-cell-transplant/home/ovc-20384860. Accessed December 23, 2021.
  30. Davis CP. Medical definition of heredity. MedicineNet; 2021. https://www.medicinenet.com/heredity/definition.htm. Accessed December 23, 2021.
  31. Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th Garland Science; 2001. Appendix I. Immunologists’ Toolbox. https://www.ncbi.nlm.nih.gov/books/NBK10755/. Accessed January 3, 2022.
  32. Davis CP. Medical definition of inheritance. MedicineNet; 2021. https://www.medicinenet.com/inheritance/definition.htm. Accessed January 3, 2022.
  33. Ambrosi A, Di Serio C. Vectors and integration in gene therapy: statistical considerations. J Comput Sci Syst Biol. 2009;2:117-123. https://www.omicsonline.org/ArchiveJCSB/Ft02/JCSB2.117.php. Accessed January 3, 2022.
  34. Aiuti A, Biasco L, Scaramuzza S, et al. Lentiviral hematopoietic stem cell gene therapy in patients with Wiskott-Aldrich syndrome. Science. 2013;341. doi: 10.1126/science.1233151. [PubMed]
  35. Biasco L, Pellin D, Scala S, et al. In vivo tracking of human hematopoiesis reveals patterns of clonal dynamics during early and steady-state reconstitution phases. Cell Stem Cell. 2016;19:107-119. doi: 10.1016/j.stem.2016.04.016 [PubMed]
  36. Biffi A, Montini E, Lorioli L, et al. Lentiviral hematopoietic stem cell gene therapy benefits metachromatic leukodystrophy. Science. 2013;341. doi: 10.1126/science.1233158 [PubMed]
  37. Lentiviral vectors. GeneTherapyNet; 2021. http://genetherapynet.com/viral-vector/lentiviruses.html. Accessed January 3, 2022.
  38. Medical Science Navigator. Physiology of self renewal; 2022. https://www.medicalsciencenavigator.com/physiology-of-self-renewal/. Accessed January 3, 2022.
  39. Davis CP. Medical definition of lymphocyte. MedicineNet; 2021. https://www.medicinenet.com/lymphocyte/definition.htm. Accessed January 3, 2022.
  40. Davis CP. Medical definition of lysosome. MedicineNet; 2021. https://www.medicinenet.com/lysosome/definition.htm. Accessed January 3, 2022.
  41. Davis CP. Medical definition of macrophage. MedicineNet; 2021. https://www.medicinenet.com/macrophage/definition.htm. Accessed January 3, 2022.
  42. The Green Lab at University of California, Irvine. Microglial function in the healthy brain. https://faculty.sites.uci.edu/kimgreen/bio/microglia-in-the-healthy-brain/. Accessed November 4, 2021.
  43. Diseases treated by gene therapy. GeneTherapyNet; 2021. http://genetherapynet.com/diseases-treated-by-gene-therapy.html. Accessed January 3, 2022.
  44. American Cancer Society. Types of stem cell and bone marrow transplants; 2020. https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/stem-cell-transplant/types-of-transplants.html. Accessed November 17, 2020.
  45. Stöppler MC. Medical definition of neuropathy. MedicineNet; 2021. https://www.medicinenet.com/neuropathy/definition.htm. Accessed January 3, 2022.
  46. SEER Training Modules, Cell Structure. National Institutes of Health, National Cancer Institute; 2022. https://training.seer.cancer.gov/anatomy/cells_tissues_membranes/cells/structure.html. Accessed January 3, 2022.
  47. Stöppler MC. Medical definition of pathophysiology. MedicineNet; 2021. https://www.medicinenet.com/pathophysiology/definition.htm. Accessed January 3, 2022.
  48. Manal N. What is peripheral blood? Sciencing; 2017. https://sciencing.com/what-peripheral-blood-4672930.html. Accessed January 3, 2022.
  49. Chawla J. Peripheral nervous system anatomy. Medscape; 2016. https://emedicine.medscape.com/article/1948687-overview. Accessed January 3, 2022.
  50. Stöppler MC. Medical definition of platelet. MedicineNet; 2021. https://www.medicinenet.com/platelet/definition.htm. Accessed January 3, 2022.
  51. Stöppler MC. Medical definition of polygenic disease. MedicineNet; 2021. https://www.medicinenet.com/polygenic_disease/definition.htm. Accessed January 3, 2022.
  52. American Society of Gene & Cell Therapy. Glossary; 2021. asgct.org/education/more-resources/glossary. Accessed December 23, 2021.
  53. Stöppler MC. Medical definition of red blood cells. MedicineNet; 2021. https://www.medicinenet.com/red_blood_cells/definition.htm. Accessed January 3, 2022.
  54. Shelf life. Medical Dictionary for the Health Professions and Nursing; 2012. http://medical-dictionary.thefreedictionary.com/Shelf-life. Accessed January 3, 2022.
  55. Schreiner E. Specialized cells in the body. Sciencing.com; 2019. https://sciencing.com/specialized-cells-body-7245490.html. Accessed January 3, 2022.
  56. Marks JW. Medical definition of stem cell. MedicineNet; 2021. https://www.medicinenet.com/stem_cell/definition.htm. Accessed January 3, 2022.
  57. BD Editors. Substrate definition. Biology Dictionary; 2017. https://biologydictionary.net/substrate/. Accessed January 3, 2022.
  58. Merriam-Webster; 2022.: https://www.merriam-webster.com/dictionary/transgene. Accessed January 3, 2022.
  59. Charrier S. Ferrand M, Zerbato M, et al. Quantification of lentiviral vector copy numbers in individual hematopoietic colony-forming cells shows vector dose-dependent effects on the frequency and level of transduction. Gene Ther. 2011;18:479-487. [PubMed]