Tissue Engineering and Articular Cartilage

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Questions and Answers

What is a significant disadvantage of using hydrogels for cell scaffolding?

Formation of isotropic neocartilage and low mechanical properties. (correct)

High water content promotes chondrogenesis.

Favors the creation of 3D structures.

Demonstrates excellent mechanical properties.

Which type of scaffold is characterized by flattened cells?

Foam or sponges

Multi-zonal scaffolds

Hydrogels

Fibrous scaffolds (correct)

What is a primary advantage of foam or sponge scaffolds?

Low water content and easy production

Interconnected porous structure and hydrophilic nature.

Formation of defined structures and good mechanical properties. (correct)

Multi-layered material properties.

What challenge must be addressed when finding the optimal scaffold for tissue engineering?

Ensuring mechanical integrity and the capacity to withstand applied loads. Signup and view all the answers

Which strategy involves using both cartilage and bone components in a scaffold?

Multi-phasic scaffold Signup and view all the answers

What is the primary purpose of lubrication in articular cartilage?

To reduce friction between two moving parts Signup and view all the answers

Which type of lubrication involves lubricin forming a monolayer on each articular surface?

Barrier lubrication Signup and view all the answers

In film-fluid lubrication, what does hydrodynamic lubrication primarily achieve?

Generation of fluid resistance and surface separation Signup and view all the answers

What characterizes film-press lubrication?

Perpendicular movement generating viscous resistance Signup and view all the answers

What predominates in areas of greater friction during mixed lubrication?

Barrier lubrication Signup and view all the answers

How does viscoelasticity manifest in articular cartilage under load?

Constant deformation with rapid initial change Signup and view all the answers

What is the distinction between film-fluid lubrication and barrier lubrication?

Barrier lubrication is contact-based, whereas film-fluid allows sliding Signup and view all the answers

What is one characteristic of articular cartilage under a constant load?

It exhibits slow, progressive deformation over time Signup and view all the answers

What is a key characteristic of inadequate cartilage compression related to patellar chondropathy?

Patella orientation and/or position Signup and view all the answers

Which muscle is specifically highlighted as a vital dynamic stabilizer in patellar stability?

Vastus medialis Signup and view all the answers

What type of trauma may lead to patellar subluxation?

Indirect trauma involving falls Signup and view all the answers

In the context of cartilage regeneration, what is microfracture?

Debridement of cartilage and drilling into subchondral bone Signup and view all the answers

What is a disadvantage of the microfracture technique in cartilage regeneration?

The entire subchondral plate must be removed Signup and view all the answers

Which of the following factors contributes to abnormal patellofemoral morphology?

Patella dislocation during fetal life Signup and view all the answers

What does a greater than 20-degree Q angle indicate?

Defect of stabilizers leading to malalignment Signup and view all the answers

What outcomes can imbalance of the patellar structure lead to?

Hyperextension and potential luxation Signup and view all the answers

What is a major drawback of autologous chondrocyte implantation (ACI)?

It is a very long process. Signup and view all the answers

Which process is involved in autologous chondrocyte implantation (ACI)?

Biopsy of healthy cartilage followed by chondrocyte expansion. Signup and view all the answers

What has been a main challenge in tissue engineering for cartilage?

Creating tissue with mechanical properties akin to mature cartilage. Signup and view all the answers

What is a potential limitation of fibrocartilage in relation to joint functionality?

It does not adequately support load during joint movement. Signup and view all the answers

What is a significant advantage of osteochondral auto-grafts compared to allo-grafts?

Lower risk of immunogenicity. Signup and view all the answers

What factor limits the length of post-operative treatment in osteochondral grafts?

The graft type and integration process. Signup and view all the answers

In the process of preparing for autologous chondrocyte implantation (ACI), what is the timeframe after which chondrocyte injection occurs?

6 weeks to 18 months after cell expansion. Signup and view all the answers

What is a benefit of physical exercise in relation to joint health?

It helps to promote the growth of muscle fiber volume, supporting the joints. Signup and view all the answers

Which of the following is a characteristic of muscle strength training for osteoarthritis?

Multipoint intermittent isometric training helps enhance muscle strength without inducing pain. Signup and view all the answers

What is the primary focus of joint activity training?

To improve joint mobility and alleviate tissue adhesion. Signup and view all the answers

In terms of aerobic exercise, which statement is accurate?

Swimming and cycling are preferred to avoid high joint loads. Signup and view all the answers

What role does aquatic exercise therapy play in joint care?

It has low water pressure that can promote cartilage self-repair. Signup and view all the answers

What characteristic is essential for scaffolds used in cartilage tissue engineering?

Biodegradability and biocompatibility Signup and view all the answers

What is a major concern with using autologous chondrocyte cell lines?

They may lead to the formation of tumors due to unlimited proliferation Signup and view all the answers

Which of the following statements about mesenchymal stem cells is accurate?

Their chondrogenic potential is significantly low. Signup and view all the answers

Which natural polymer is mentioned as promoting the re-differentiation of encapsulated chondrocytes?

Hyaluronan Signup and view all the answers

What is a significant benefit of synthetic polymers in scaffold matrices?

Ease of processing and control of degradation times Signup and view all the answers

Chondroprogenitor cells are highlighted for their:

Proliferation without tumor formation Signup and view all the answers

During in vivo tissue development, what property must scaffolds maintain?

They need to remain intact until implantation. Signup and view all the answers

What is a common misconception regarding the reliability of chondrocyte cell lines?

They achieve full phenotypic changes seen in vivo. Signup and view all the answers

Study Notes

Cartilage Composition and Structure

Cartilage is a white, solid, strong, and elastic connective tissue.
It's crucial for supporting and enabling movement of body parts.
Cartilage doesn't contain blood vessels or nerves.
Functions include: bone movement in joints, providing a framework for some organs, and shaping long bones.

Types of Cartilage

Hyaline cartilage (articular cartilage): Common, with few cells and fibers, surrounded by perichondrium.
Elastic cartilage: Features numerous, large chondrocytes, rich in elastic fibers, also surrounded by perichondrium.
Fibrocartilage: Has intermediate characteristics between dense connective tissue and hyaline cartilage. Chondrocytes are arranged in rows, containing collagens I and II, and lacks perichondrium.

Components of Articular Cartilage

Extracellular matrix: Consists of fibers and ground substance.
Cells: Include chondrogenic cells, chondroblasts, and chondrocytes.
Perichondrium: Connective tissue surrounding cartilage.

Chondrogenic Cells and Development

Chondrogenic cells (stem cells) differentiate into chondroblasts.
Chondroblasts mature into chondrocytes.
Chondrocytes maintain and maintain extracellular matrix.
Chondrocytes are found inside lacunae, or chondroplasts.

Articular Cartilage Structure

Surface zone: Elongated chondrocytes in parallel arrangement with surface collagen.
Intermediate zone: Chondrocytes without specific order.
Deep zone: Chondrocytes arranged in groups perpendicular to the surface with collagen.
Calcified zone: Contains calcified matrix.

Cartilage Locations

Articular cartilage is found in various locations, including the skeleton, growth plates, nasal septum, and the surfaces of mobile joints (e.g., knees, ankles, hips).

Lubrication of Articular Cartilage

Barrier lubrication: Lubricin (a glycoprotein) forms a monolayer on articular surfaces.
Film-fluid lubrication: Fluid separation between surfaces supports load.

Cartilage Wear

Cartilage wear is related to imbalance between synthesis and degradation.
Factors like overweight accelerate wear.
Age produces changes in cells, leading to decreased tissue maintenance and increasing wear.
Overuse of joints causes repetitive loads that lead to tissue deformity.

Cartilage Injuries

Chondropathics: Minor repetitive trauma, pressure from cartilage, or direct trauma.
Osteochondritis: Gradual wear from excess load or synovial fluid viscosity change/injury to cartilage.
Osteochondritis dissecans: Degeneration of central zone of cartilage, thickening of perichondrium/cartilage edge; possible ossification, bone "mice."

Tissue Engineering for Cartilage Repair

Microfracture: Removes damaged cartilage and creates fibrocartilage.
ACI (Autologous chondrocyte implantation): A two-stage approach that is surgically intensive, involves cartilage biopsy and in vitro chondrocyte expansion, then implantation.
Osteochondral auto- and allografts: A surgical cartilage transplant including the subchondral bone.

Cell Sources and Culture Conditions

Autologous chondrocytes are lines that may not reflect phenotypic changes found in vivo or lead to tumors from unlimited proliferation.
Mesenchymal stem or chondroprogenitor cells better alternatives to stem cells.

Biomaterials

Matrices: Biocompatible, biodegradable scaffolds capable of supporting and stimulating chondrogenesis, to support joint load.
Natural polymers: Collagen, hyaluronic acid, etc.
Synthetic polymers: Polymers provide mechanical support and control degradation.

Future Challenges and Exercise for Cartilage

Challenges include finding optimal scaffolds, cell sources, and mimicking cartilage development in vitro.
Exercise can prevent damage and improve joint function by preventing/reducing cartilage wear, increasing ligament function, and improving muscle and strength.

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Description

This quiz explores the properties and challenges of scaffolds used in tissue engineering, particularly focusing on hydrogels, foam, and sponge scaffolds. It also examines the lubrication mechanisms of articular cartilage, including various lubrication strategies and their implications for joint health.