Biomaterials and Cell Interactions Quiz

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Questions and Answers

Which property is NOT part of ligand properties that affect cell-material interactions?

Identity

Surface chemistry (correct)

Density/clustering conformation

Microenvironment

What technique is used to assess cell adhesion and morphology?

Gene expression analysis

Viability assays

Western blotting

Microscopy techniques (correct)

Which assay helps determine the percentage of viable cells?

Live/dead assay (correct)

Metabolic activity assay

Histological analysis

Cell motility assay

What is the first step in the Trypan blue exclusion assay?

Centrifuge the cell suspension Signup and view all the answers

Which property is assessed in the analysis of cell-material interactions?

Cell proliferation Signup and view all the answers

In a live/dead assay, what does calcein-AM indicate?

Viable cells Signup and view all the answers

Which of the following is NOT a characteristic of material properties affecting cell interactions?

Adhesion Signup and view all the answers

What is the primary consideration when determining if a scaffold is immunogenic?

The need for immunological suppressor drugs if it is immunogenic Signup and view all the answers

Which category of materials is primarily used in orthodontics?

Ceramics Signup and view all the answers

What is the role of EthD-1 in the live/dead assay?

Identifies cells with compromised membranes Signup and view all the answers

What property is essential for a scaffold to support cell attachment?

Mechanical properties similar to host tissue Signup and view all the answers

Which combination accurately represents a biodegradable metal used for bone tissue regeneration?

Iron-based alloys Signup and view all the answers

What effect does higher porosity have on metal scaffolds?

Higher degradation rate Signup and view all the answers

Which of the following materials is obtained through industrial polymerization?

Polylactic acid Signup and view all the answers

Which of the following is NOT a requirement for choosing scaffold materials?

High elasticity under tensile stress Signup and view all the answers

What types of materials are classified as composite materials in scaffold design?

A mix of ceramics and polymers Signup and view all the answers

What defines biocompatibility in the context of materials?

The ability to locally trigger non-fibrotic wound healing Signup and view all the answers

Which of the following statements about cytotoxicity tests is true?

Mammalian cells used in tests often come from mouse or human origins. Signup and view all the answers

When is a cell monolayer considered to be at 100% confluence?

When all surface area of the well is covered by cells Signup and view all the answers

What type of cytotoxicity test involves materials being placed directly onto cell monolayers?

Direct contact test Signup and view all the answers

Which characteristic is essential for material tests to standardize protocols across labs?

Established cell lines should exhibit standard behavior Signup and view all the answers

In an indirect contact test utilizing agar diffusion, what is the purpose of the agar overlay?

To cushion the cells from physical effects caused by samples Signup and view all the answers

What is a critical requirement for materials used in direct contact tests?

Materials can be placed prior to seeding cells if they support cell adhesion Signup and view all the answers

Which of the following is NOT a type of cytotoxicity test?

Mechanical testing Signup and view all the answers

What does the crossover point (G' = G”) indicate in the context of oscillation frequency sweep?

The transition from liquid-like to solid-like behavior. Signup and view all the answers

How does the behavior of uncrosslinked polymers differ at low frequencies compared to crosslinked polymers?

Crosslinked polymers display more liquid-like than solid-like behavior. Signup and view all the answers

What occurs to the tanδ value at the gel point?

It equals 1. Signup and view all the answers

What characterizes the behavior of a viscoelastic solid in oscillation frequency sweeps?

G' is constant while G” increases with frequency. Signup and view all the answers

Which material displays a liquid-like behavior at lower frequencies during frequency sweeps?

Viscoelastic liquid. Signup and view all the answers

What is true about the behavior of gel-like materials during frequency sweeps?

G' and G” are constant across different frequencies. Signup and view all the answers

What defines the relaxation time in the context of viscoelastic materials?

Time taken for stored elastic stresses to convert to viscous stresses. Signup and view all the answers

At high frequencies, what behavior do viscoelastic liquids exhibit?

G' dominates over G”. Signup and view all the answers

What is the primary function of epithelial cells?

To provide protection to organs and cavities Signup and view all the answers

What is a characteristic unique to pluripotent stem cells?

They can differentiate into any cell type of the adult body Signup and view all the answers

Which type of stem cells contribute to tissue homeostasis?

Adult stem cells Signup and view all the answers

What type of differentiation capability do mesenchymal stem cells (MSCs) have?

They can differentiate into osteocytes, chondrocytes, and adipocytes Signup and view all the answers

During self-renewal, what can each daughter cell of a stem cell potentially become?

Either a stem cell or a differentiated cell Signup and view all the answers

Which tissue is considered non-prolific in terms of adult stem cell presence?

Brain Signup and view all the answers

What defines the blastocyst stage in mammalian development?

It lasts from the 4th to the 14th day after fertilization Signup and view all the answers

What is a distinguishing property of adult stem cells compared to other stem cell types?

They are found in specific organs or tissues Signup and view all the answers

What characterizes viscoelastic materials?

They exhibit both viscous and elastic behavior. Signup and view all the answers

What effect does increased shear strain have on pseudoplastic fluids?

Viscosity decreases as shear rate increases. Signup and view all the answers

What happens to polymer chains during shear thinning?

They disentangle, reducing viscosity. Signup and view all the answers

How is shear strain expressed for solid materials subjected to applied stress?

𝜏 = G𝛾 Signup and view all the answers

What is the defining characteristic of thixotropic materials?

They show a viscosity that decreases with time under constant shear. Signup and view all the answers

Which of the following materials typically exhibits shear thickening behavior?

Starch dispersion Signup and view all the answers

What is the relationship between shear rate and viscosity in dilatant fluids?

Viscosity increases with increasing shear rate. Signup and view all the answers

What type of rheological behavior do purely viscous materials demonstrate?

They dissipate all energy as heat. Signup and view all the answers

Study Notes

Organ Donation and Transplantation

Involves thousands of clinicians, professionals, and volunteers
Donated organs require special preservation methods for viability after procurement and transportation
Organ transplantation remains the first choice for several diseases, but statistics are unsustainable
Regenerative medicine seeks to replace or establish function of human cells, tissues, or organs

Regenerative Medicine

Focused on developing treatments to restore tissue and organ function lost due to aging, disease, damage or defects
Combines cell transplantation, material science (scaffold), and bioengineering knowledge

Tissue Engineering Paradigm

Set of tools at the interface of biomedical and engineering sciences
Aims to support the growth of living cells or attract endogenous cells to aid tissue formation or regeneration
Three models: in-vitro (lab), in-vivo (body, usually animals), ex-vivo (organ in synthetic environment)

Tissue Engineering Phases

Phase 1: In-vitro formation of a Tissue Construct, in which cells proliferate and produce extracellular matrix (natural scaffold)
Phase 2: In-vivo remodeling of the Construct to the appropriate anatomic location, recapitulating the normal functional architecture of an organ or tissue

Key Processes in Tissue Engineering

Cell Proliferation, sorting, and differentiation
Extracellular matrix production and organization
Degradation of the scaffold or integration in the body
Remodeling and growth of the tissue, crucial for integration

TE Objectives

Understand the structure-function relationship in normal and pathological tissues
Create models for human tissues that can be used for detecting toxins or infections, and are ideal for high-throughput drug testing
Control cell and tissue response to injury, physical stimuli, and biomaterial surfaces through chemical, pharmacological, mechanical, immunological, and genetic manipulation

Past Successes in Tissue Engineering

Integro Dermal Regeneration Template (2002): acellular device for skin regeneration
Infused bone grafts (2002): bone morphogenetic protein-2 on a collagen sponge
Transcyte fibroblast culture on nylon mesh (1997), no need for immunosuppressant drugs
Apigraf and Dermagraft for venous ulcers and diabetic foot ulcers, respectively

Cell Therapy

Cell isolation and expansion
Cell engraftment at the target site
Conciliation between autologous and allogeneic cell sources

Cell Types for Cell Therapy

Average number of requested cells: 10⁷-10⁹
Examples: Autologous chondrocytes transplant (30x10⁶), Lymphocytes transplant (>0.5x10⁹), Bone marrow transplant (10x10⁹)

Proliferative Potential of Cultured Human Cells

Fibroblasts: > 10³x
Lymphocytes T: 10³-10⁴x
Chondrocytes: 10-20x
Hematopoietic cells: 10x
Epatocyts: ≈0
Cardiomyocytes: ≈0

Scaffolds

Provide structural and mechanical support for cell attachment and subsequent tissue development
Can be with or without cells
Interface with the tissue
Mimic the structure and function of the extracellular matrix

Scaffolding Approaches

Top-down: scaffold + cells → tissue construct
Bottom-up: tissue modules (module of scaffold + cell) → tissue construct

Scaffolding Technology Examples

Electrospinning
Melt-spinning
Free-drying
Self-assembly
Fused deposition modeling
Bioprinting

Cell Therapy Summary

Cell isolation and/or expansion
Encouragement of cell engraftment at target site
Conciliation between autologous and allogeneic cell sources

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Description

Test your knowledge on the properties of ligands and their effect on cell-material interactions. Explore various assays like Trypan blue exclusion and live/dead assays that help assess cell viability and adhesion. Prepare to delve into the essential characteristics of biodegradable materials and their applications in fields like orthodontics and tissue regeneration.