tissue engineering 1

tissue engineering

tissue engineering

practice of combining scaffolds, cells, & biologically active molecules into functional tissues

goal of tissue engineering

to assemble functional constructs that restore, maintain, or improve damaged tissues/whole organs

regenerative medicine

broad field that includes tissue engineering but also incorporates research on self

where and when was the term "tissue engineering" coined

nsf

cells

building blocks of tissue

tissues

basic unit of function in the body

extracellular matrix

groups of cells make & secrete their own support structures

matrix/scaffold

also acts as a relay station for various signaling molecules

signal

each can start a chain of responses that determine what happens to the cell

building a scaffold

proteins to plastics once created, cells w/ or w/o growth factors can be introduced right environment, tissue develops all mixed together, tissue self

create new tissue used an existing scaffold

cells of donor organ are stripped and remaining collagen is used

supplemental bladders, small arteries, skin grafts, cartilage, & trachea

have been implanted but procedures are still experimental & very costly

complex organs

heart, lung, liver tissue

complex tissues

useful in research, in drug development

functioning human tissue

help screen medication candidates could speed up development save money, reduce # of animals used for research

biomaterial

pigs intestine

6 research areas of tissue engineering

1. development of new biomaterials/scaffolds

2. id of optimal cell sources

3. biomolecules

4. engineering methods & design

5. functional assessment of engineering tissues

6. informatics as applied to tissue engineering

novel biomaterials

designed to direct the growth, differentiation, & organization of cells in the process of forming functional tissue by providing physical, chemical, & mechanical cues

6 cell sources for tissue engineering

1. autologous

2. allogeneic

3. syngeneic

4. xenogeneic

5. stem & progenitor

6. genetically engineered

stem cell research

involves stem cells, whether from embryonic, fetal, or adult sources, human & non

2 stem cell research purpose

stem cells are isolated, derived, or cultures to develop cell/tissue therapies, studying cell differentiation

to understand the factors necessary to direct cell specialization to specific pathways, & other developmental studies

NOT stem cell research

transgenic studies, gene knockout studies, generation of chimeric animals

first Us clinical trial of pt

derived stem cell therapy

first US pt receieves autologous stem cell therapy

to treat dry AMD

5 examples of biomolecules

1. angiogenic factors

2. growth factors

3. differentiation factors

4. transcription factors

5. bone morphogenic proteins

ex

bioinformatics

including the application of tools & info from many areas of informatics to the design & characterization of engineered tissue

ex

8 engineering design aspects

1. 2d cell expansion/scale

functional assessment of engineered tissues

new imaging tools for real

what are NIH

funded researchers developing?

what are NIH

funded researchers projects? (6)

ex of engineered tissues that have been approved by the FDA

artificial skin & cartilage

people in TE

1. robert langer

the pcr method

technique used to make many copies of a selected DNA sequence

ECG, EKG electrocardiogram, electrocardiography

a recording of the electrical activity of the heart

positron emission topography (pet)

an imaging technique used to see which brain areas are being activated while performing tasks

GeneChip/RNA

seq gene expression study

single cell transcriptomes analysis (scRNA

seq)

retinal organoids

derived from induced pluripotent skill cells have the potential to be used for modeling human diseases

(6) what are the fundamentals of tissue engineering?

1. cells

2. tissues

3. homeostasis

4. signaling

5. ecm

6. biomaterials

(8) what are the tools of tissue engineering?

1. microscopy

2. bioimaging

3. pcr

4. dna sequencing

5. gene expression profiling

6. gene delviery/therapy

7. bioMEMS

8. nanotechnology

quantitative cell & tissue biology

tissue organization, tissue dynamics, morphogenesis, stem cells, cellular fate processes, & their coordination

cell & tissue characterization

high

engineering methods & design

time constant analysis, scale

clinical implementation

conventional approaches to tissue repair, host integration, & producing tissue

overview of tissue engineered

based approach using 3d

treating female infertility

healthy donor tissue/organ

tissue engineered endometrium

inner lining membrane of the uterus

collagen i & matrigel cell

causes of female infertility

chemo uterine injuries fallopian tube occlusion hysterectomy massive intrauterine adhesions congenital uterine malformations

how can we fabricate tissue engineered grafts for female reproductive organ?

1. biomaterial fabrication

2. cell isolation & expansion

3. cell seeding

4. scaffold conditioning

5. implantation

layered approach

tissue engineered endometrium

combined approach

tissue engineered endometrium

bio printing strategies for bio fabrication

1. extrusion bio printing

why is TE necessary? (5)

1. congenital abnormalities require tissue reconstruction

2. most tissues cannot regenerate following a disease/injury

3. even tissues that regenerate spontaneously may not completely do so if defects are large

4. transplantation is limited by the scarcity if donor tissue

5. permanent implants have a lot if success, but also lots of problems

opportunities for commercialization

1. biomaterials

general criteria for product develpment

1. fulfills unmet need in potentially large markets

2. shows strong likelihood of technical feasibility, efficacy, & cost effectiveness

3. unique to the market

4. time to market less than five years

5. cost to market within financial means without undue risk

storage & transportation companies

integra life sciences corp lifecell corp

where do we stand?

on market

spinal muscular atrophy

caused by the deletion/mutation of the survival motor neuron 1 (smn1) gene

smn1 gene

produces survival motor neuron protein that is critical for normal function of motor neurons

zolgensma

designed to enable rapid & continuous expression of smn protein

limited success

full regeneration of tissues that do not regenerate spontaneously has not been achieved (success with bone, engineered skin has no glands, hair/nerves)

autografts

harvesting tissue from a pt's own body for transplanting into the same pt

allografts

harvesting tissue from a donor, transplanting in a pt, deceased/living donors

xenografts

removing tissue from animals from transplantation into a human

• available supply, standardized products

man made materials & devices

artificial heart, heart valves, prosthetic hips, etc.

• fill short term needs

stem cell therapy

the use of stem cells to treat/prevent a disease/condition

what is a stem cell?

a single cell that can replicate itself/differentiate into many cell types

why self

renew & differentiate?

where are stem cells found?

embryonic stem cells (blastocyst

embryonic stem (ES) cells: where we find them?

isolated from very young mammalian embryos blastocyst

embryonic stem (ES) cells: what can they do?

pluripotent

embryonic stem (ES) cells: challenges

tumorigenicity immune rejection genomic stability limited sources heterogeneity

tissue stem cells: where we find them?

surface of the eye, brain, breast, skin, testicles, intestines, muscles, bone marrow

tissue stem cells: why we need them?

essential for keeping us fit & healthy replace cells that are damages/used up

tissue stem cells: what can they do?

multi potent

tissue stem cells: principles of renewing tissues

stem cell

tissue stem cells: hematopoietic stem cells

found in the bone marrow & responsible for the continual production of blood cells

tissue stem cells: neural stem cells

found in the nervous system, primarily in the brain & spinal cord, they are responsible for the continuous generation of new neurons

tissue stem cells: gut stem cells

primarily located in the lining of the gastrointestinal tract, they play a vital role in maintaining & repairing the continuous cell turnover in the gut, as the gut lining is constantly exposed to mechanical & chemical stresses.

tissue stem cells: mesenchymal stem cells

found in bone marrow, adipose (fat) tissue, and the stroma of many organs, they differentiate into bone cells (osteoblasts), cartilage cells (chondrocytes), & fat cells (adipocytes)f

differences b/n embryonic & tissue stem cells

1. different self

niche

microenvironment around stem cells that provides support & signals regulating self

iPS stem cells

type of pluripotent stem cell that can be generated directly from adult cells

somatic cell nuclear transfer (SCNT)

method of reproductive cloning in which genetic material is transferred from an adult somatic cell into an unfertilized, enucleated egg

iPS research

solution to the problems of immune rejection & use of human embryos to create new stem cell lines, shinya yamanaka

what are iPSCs?

adult cells that have been genetically reprogrammed to an embryonic stem cell

reversing cell differentiation advantages

introduce specific transcription factors (e.g., Oct4, Sox2, Klf4, and c

role of 4 factors during reprogramming

oct3/4 & sox2

retroviral transduction

any of a group of RNA viruses that insert a DNA copy of their genome into the host cell by a virus/viral vector in order to replicate

immunocytochemistry

a method that involves fixing the cells, incubating them w/ antibodies specific to stem cell markers, & visualizing the expression of these markers through fluorescence microscopy to confirm their pluripotency

microarray analysis

allows researchers to assess gene expression patterns of iPSCs

by comparing the transcriptome (the set of all expressed genes) of iPSCs to other cell types/developmental stages, scientists can identify genes that are specifically upregulated/downregulated in iPSCs

activation of ES‐cell gene promoters

initiate and enhance gene transcription, maintaining the pluripotency of embryonic stem (ES) cells

luciferase reporter assay & chromatin immunoprecipitation

telomerase activity & exponential growth

telomeres are protective caps at the ends of chromosomes, & they shorten w/ each cell division telomerase is an enzyme that can prevent/even reverse this shortening, ensuring that cells can divide repeatedly

in stem cells, telomerase activity is often high, allowing them to divide extensively & contribute to tissue repair & regeneration

spontaneous differentiation (in vitro)

process by which undifferentiated/pluripotent stem cells undergo differentiation into more specialized cell types w/o the specific induction of differentiation factors/cues

this natural process occurs in cell culture conditions when stem cells are allowed to proliferate & mature over time

directed differentiation to neural cells (in vitro)

process where stem cells/other precursor cells are manipulated to become specialized neural cells in a controlled laboratory setting

teratoma

monster tumor, contains tissue from all 3 germ layers

allows us to determine if cells are pluripotent

indirect lineage conversion

relies on the use of transcription factors associated w/ pluripotency

on forced expression, these factors first lead to removal of differentiate marks, creating an unstable state suitable for further differentiation on exposure to appropriate signals

direct lineage conversion (transdifferentation)

lineage reprogramming, process where one mature somatic cell transforms into another mature somatic cell w/o undergoing an intermiediate pluripotent state/progenitor cell type

ex: neurons, cardiomyocytes

Brn2, Ascl1, Myt1l

factors can generate functional neurons from human pluripotent stem cells as early as 6 days after transgene activation

when combind w/ basic helix

gene expressed in neural tissues

19, important roles in neural development/epigenetic reprogramming