Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Tissue Engineering: Principles, Techniques, and Applications, Exams of Biomedical Engineering

A comprehensive overview of tissue engineering, covering key concepts such as stem cells, scaffolds, bioreactors, and nanomaterials. it details various stem cell types, their applications in tissue engineering, and the challenges associated with their use. the document also explores different scaffold fabrication methods, including electrospinning and 3d printing, and discusses the role of bioactive factors in tissue regeneration. This resource is ideal for students studying biomedical engineering, regenerative medicine, or related fields.

Typology: Exams

2024/2025

Available from 05/13/2025

tizian-kylan
tizian-kylan ๐Ÿ‡บ๐Ÿ‡ธ

2.7

(21)

3.8K documents

1 / 21

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Tissue Engineering Questions and
Answers Rated A+
Tissue Engineering โœ”โœ”An interdisciplinary field that applies the principles of engineering and
life sciences toward the development of biological substitutes that restore, maintain, or improve
tissue function.
Stem Cells โœ”โœ”A cell that has the ability to self renew and differentiate into various other
specialized cell types.
Cells in Tissue Engineering โœ”โœ”Cell Location (based on tissue types):
- Skin cells for skin tissue engineering
- Chondrocytes for cartilage tissue engineering cells sources: autologous, allogenic, xenogenic
- Stem cells for various tissue engineering: embryonic stem cells, induced pluripotent stem cells
(IPS), adult stem cells
Scaffold in Tissue Engineering โœ”โœ”- Natural Scaffolds
- Synthetic Scaffolds
- Polymers
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff
pf12
pf13
pf14
pf15

Partial preview of the text

Download Tissue Engineering: Principles, Techniques, and Applications and more Exams Biomedical Engineering in PDF only on Docsity!

Tissue Engineering Questions and

Answers Rated A+

Tissue Engineering โœ”โœ”An interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function.

Stem Cells โœ”โœ”A cell that has the ability to self renew and differentiate into various other specialized cell types.

Cells in Tissue Engineering โœ”โœ”Cell Location (based on tissue types):

  • Skin cells for skin tissue engineering
  • Chondrocytes for cartilage tissue engineering cells sources: autologous, allogenic, xenogenic
  • Stem cells for various tissue engineering: embryonic stem cells, induced pluripotent stem cells (IPS), adult stem cells

Scaffold in Tissue Engineering โœ”โœ”- Natural Scaffolds

  • Synthetic Scaffolds
  • Polymers
  • Ceramics
  • Nano/micro tubes and fibers
  • Composites

Bioreactors โœ”โœ”- System where conditions are closely controlled to permit and induce a certain behavior in living cells or tissues

  • Provide controlled and steady flow of cell media
  • Factors necessary for cell growth: pH, temp., pressure, nutrient supply, waste removal
  • Type of Bioreactors: spinner flasks, rotating vessels, hollow fiber, perfusion reactors

Two Key Features of Stem Cells โœ”โœ”- Self-renewal capacity (can copy themselves)

  • Multi-differentiation potency (can differentiate to different cell environments)

Types of Stem Cells โœ”โœ”Totipotent: cells can develop into a new individual cells from early embryos (1-3 days)

Pluripotent: cells can give rise to any fetal or adult cell type (over 220); the inner cell mass of blastocyst from early embryo (5 to 14 days)

Multipotent: cells can give rise to cells from multiple, but a limited number of lineages; cord blood and adult stem cells

  • Most embryonic stem cells are from embryos that develop from an invitro fertilization (IVF) clinic - and then donated for research purposes with informed consent of the donors

Potential Solutions (Embryonic Stem Cells) โœ”โœ”- Teratoma formation -> Pre-differentiate cells in culture then insert

  • Animal Pathogens -> Feeder-free culture conditions
  • Immune Response -> Somatic cell nuclear transfer
  • Ethics -> Scientists have announced the development of 5 human embryonic stem cell lines without the destruction of embryos
  1. Single cells were removed from embryos
  2. The embryos continued to develop normally and were then frozen
  3. The removed cell was cultured in optimal culture environments

Pluripotent Stem Cells: Induced Pluripotent Stem Cells (iPS) โœ”โœ”- iPS cells are a type of artificial pluripotent stem cells derived from adult cells, which were genetically reprogrammed to add certain genes

  • They are similar to natural embryonic stem cells and differentiate into specialized cells. But no need for embryos.

Summary of iPS Cells โœ”โœ”Stengths:

  • Autologous cell source to potentially avoid immune responses
  • Similar to embryonic stem cells without using an embryo

Major Limitations:

  • Tumor formation and less safe than hESCs

Multipotent Stem Cells: Human Mesenchymal Stem Cells โœ”โœ”- MSCs are multipotent stem cells that are of stromal origin can differentiate into a variety of cell types

  • Also called multipotent stromal cells

Sources:

  • Bone marrow
  • Fat tissue (adipose)
  • Umbilical cord

Lineages:

  • Osteogenic
  • Chondrogenic
  • Adipose
  • Myogenic

Materials Role in Tissue Engineering โœ”โœ”- Structure Support

  • Control Cellular microenvironment

Types of Materials for Biomedical Applications โœ”โœ”According to bulk properties:

  • Polymer
  • Metal
  • Ceramic
  • Composite

According to Sources:

  • Natural materials
  • Synthetic materials

Materials for Tissue Engineering โœ”โœ”Polymer: long-chain molecules that consist of a large number of small repeating units - collagen, chitosan, silk, fibrin, GAG; poly(glycolic acid), poly(lactic acid), poly(eta-coprolactone), PLGA

Ceramics: a class of inorganic solids which are prepared by action of heating and subsequent cooling - coral for bone; calcium phosphates

Composite: engineered or naturally occurring materials made from two or more constituent materials - decellularized tissue; nanocomposite

Material Criteria for Tissue Regeneration โœ”โœ”- Biocompatible

  • Biodegradable
  • Suitable surface chemistry
  • Matching mechanical properties

Nanomaterials โœ”โœ”Materials with basic structural units, grains, particles, fibers, or other constituent components smaller than 100 nm in at least one dimension ( 1 nm = 10^-9)

Natural Tissue Structure: Cells and Extracellular Matrix (ECM) โœ”โœ”The ECM promotes a unique microenvironment that fosters cell and tissue organization

Role:

  • Support cell growth
  • Regulate intercellular communication
  • Segregate tissues

CNT is configurationally equivalent to a 2-D graphene sheet rolled into a tube.

Carbon Nanotube Properties โœ”โœ”- Superior mechanical properties

  • Outstanding electric properties
  • Special surface chemical properties
  • Twice the thermal conductivity of diamonds
  • Mimicking tissue dimension
  • Excellent biocompatibility

Scaffold Roles โœ”โœ”- Provide appropriate structures support

  • Control cellular microenvironment
  • Encourage cell growth and tissue regeneration
  • Exchange nutrients and wastes

3-D and porous

Tissue Engineered Scaffold Fabrication Methods โœ”โœ”- Electrospinning

  • 3-D printing
  • Solvent casting, particle leaching, and gas foaming
  • Freeze drying
  • Phase separation

Introduction to Electrospinning โœ”โœ”- A versatile technique applicable to a wide range of polymers and solvents

  • Uses an electrical charge to draw a very fine polymer nano/micro fibers with various thickness from polymer solutions.

Applications:

  • Scaffolds for tissue engineering
  • Scaffolds for wound healing
  • Matrices for the controlled release of therapeutic molecules
  • Medical device coatings

Electrospinning vs. Electrospraying โœ”โœ”Spinning: molecular cohesion of the liquid must be sufficiently high so stream won't break up

Spraying: streams break up into droplets

  • To produce scaffolds of desired spatially distributed morphogenetics
  • To create novel core-shell fiber structure
  • To deposit nanomaterials creating desirable surface features

Wet Electrospinning โœ”โœ”A standard electrospinning setup alligned with the collector plate and submerged in a water or organic bath.

3-D Printing โœ”โœ”- 3-D printing is a process of creating 3-D objects from digital files using a materials printer

  • It was used a lot for rapid prototyping
  • Various objects such as auto parts, toys, and statues can be constructed out of a given material
  • It was used to make prototypes of new products or even the final product

3-D Printing for Tissue and Organ Regeneration โœ”โœ”- A normal inkjet printer

  • Instead of paper, petri dishes are used
  • Instead of ink cells, hydrogels, or cross-linking chemical agents are used
  • The cells are autologous from the patient

The Steps for a 3-D Printed Organ โœ”โœ”- The petri dish is filled with water or uncrosslinked hydrogel

  • When the printer "prints" the crosslink transforms the solution into a jell-o like substance which allows the cells to be put in
  • This method is repeated until the organ that you want is created

CT scan -> CAD image -> Bone scaffold fabricated from 3-D printer -> Surgeons implant customized scaffold into patient

Advantages of 3-D Printing for Tissue Engineering โœ”โœ”- Biomimetric 3-D

  • Rapid prototyping
  • Quick customization using CT scan of patient
  • Complexity of scaffold

Bioactive Factors - Growth Factors โœ”โœ”- Growth factor is a naturally occurring substance and helps facilitate cellular growth, proliferation, and differentiation

  • They typically act as signaling molecules between cells. Examples are cytokines and hormones that bind to specific receptors on their target cell surface
  • There are numerous growth factors for each tissue that can be engineered

Bone-Morphogenic Protein (BMPs) โœ”โœ”- BMPs are multi-functional growth factors that belong to the transforming growth factor-b superfamily

  • To date, around 20 BMP family members have been identified and characterized
  • Osteoprogenitors, mesenchymal cells, osteoblasts, and chondrocytes within the extracellular matrix produce BMPs
  • BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, BMP-

Research in Growth Factors for Tissue Engineering โœ”โœ”- The effects of growth factors on cells

  • Techniques to incorporate growth factors into biomatierals based scaffolds

Growth Factors for Bone and Cartilage Cells โœ”โœ”- Transforming growth factor-b superfamily

  • Platelet-derived growth factor enhances chondrocyte migration and bone healing
  • Basic fibroblast growth factor
  • Insulin-like growth factor: increase collagen and proteoglycan deposition: mitigate the injurious response of impacted cartilage by limiting the loss of matrix components

Typical Mechanical Stimulations for Cartilage Regeneration โœ”โœ”- Dynamic shear

  • Dynamic compression
  • Hydrostatic pressure

What are Bioreactors โœ”โœ”- System where conditions are closely controlled to permit and induce a certain behavior in living cells or tissues

  • Provide controlled and steady flow of cell media
  • Factors necessary for cell growth: pH, temperature, pressure, nutrient supply, waste removal

Main Objective of Bioreactors in Tissue Engineering โœ”โœ”- To establish spatially uniform cell distributions on 3-D scaffolds

  • To maintain desired concentration of gases and nutrients in the culture medium
  • To expose developing tissue to appropriate physical stimuli

Bioreactor Types โœ”โœ”- Spinner flask bioreactors

  • Rotating-wall vessels
  • Hollow fiber bioreactors
  • Perfusion bioreactors
  • Bioreactors that apply controlled mechanical forces (ex. hydrostatic chamber)

DNA Based Helical Rosette Nanotubes โœ”โœ”HRNs or RNTS are a new class of nanotubes obtained through the self-assembly of the DNA base pair building blocks (Guanine^Cytosine) in aqueous solutions.

Advantages of Self-Assembly Nanotubes/Nanofibers for Tissue Engineering โœ”โœ”- Biomimetic nano structural features

  • Ease of chemical functionalization
  • Ability to gel
  • Rapid preparation through self-assembly

Medical Application of Electrospinning โœ”โœ”- Scaffolds for tissue engineering

  • Scaffolds for wound healing
  • Matrices for the controlled release of therapeutic molecules
  • Medical device coatings

Electrospinning Materials โœ”โœ”Synthetic Polymers

  • Polyglycolic acid (PGA) -> highly crystalline, hydrophilic
  • Ploylactic acid (PLA) -> hydrophobic, lower melting temperature
  • Polycaprolactone (PCL) -> semi-crystalline properties, easily co-polymerized, mixed frequently with other materials
  • Polyvinyl alcohol (PVA) -> water soluble
  • Nylon
  • Copolymers (PLGA, PGA-PCL, PLA-PCL)

Natural Polymers

  • Elastin
  • Collagen
  • Collagen blends
  • Fibrinogen

Nanocomposites

  • Carbon Nanotubes
  • Nanocrystalline hydroxyapatites
  • Self-assembly nanotubes/nanofibers
  • Bioglasses
  • Various growth factors

3-D Printed Hard Tissue โœ”โœ”- Predesigned CAD patterns