https://yunus.hacettepe.edu.tr/~damlacetin/kmu407/index_dosyalar/4.%20makale.pdf

Biodegradable polymers as biomaterials

Three-dimensional (3D) cell culture systems have gained increasing interest in drug discovery and tissue engineering due to their evident advantages in providing more physiologically relevant information and more predictive data for in vivo tests. In this review, we discuss the characteristics of 3D cell culture systems in comparison to the two-dimensional (2D) monolayer culture, focusing on cell growth conditions, cell proliferation, population, and gene and protein expression profiles. The innovations and development in 3D culture systems for drug discovery over the past 5 years are also reviewed in the article, emphasizing the cellular response to different classes of anticancer drugs, focusing particularly on similarities and differences between 3D and 2D models across the field. The progression and advancement in the application of 3D cell cultures in cell-based biosensors is another focal point of this review.

/pdf/three-dimensional-cell-culture-systems-and-their-2yirqbq9ul.pdf

Three-Dimensional Cell Culture Systems and Their Applications in Drug Discovery and Cell-Based Biosensors

Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. In order to fit functional demand, materials with desired physical, chemical, biological, biomechanical and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.

/pdf/biomedical-applications-of-biodegradable-polymers-2db9gcyzxw.pdf

Biomedical Applications of Biodegradable Polymers

Current strategies of regenerative medicine are focused on the restoration of pathologically altered tissue architectures by transplantation of cells in combination with supportive scaffolds and biomolecules. In recent years, considerable interest has been given to biologically active scaffolds which are based on similar analogs of the extracellular matrix that have induced synthesis of tissues and organs. To restore function or regenerate tissue, a scaffold is necessary that will act as a temporary matrix for cell proliferation and extracellular matrix deposition, with subsequent ingrowth until the tissues are totally restored or regenerated. Scaffolds have been used for tissue engineering such as bone, cartilage, ligament, skin, vascular tissues, neural tissues, and skeletal muscle and as vehicle for the controlled delivery of drugs, proteins, and DNA. Various technologies come together to construct porous scaffolds to regenerate the tissues/organs and also for controlled and targeted release of bioactive agents in tissue engineering applications. In this paper, an overview of the different types of scaffolds with their material properties is discussed. The fabrication technologies for tissue engineering scaffolds, including the basic and conventional techniques to the more recent ones, are tabulated.

/pdf/polymeric-scaffolds-in-tissue-engineering-application-a-2sbenjc1po.pdf

Polymeric scaffolds in tissue engineering application: a review

Collagen and elastin networks make up the majority of the extracellular matrix in many organs, such as the skin. The mechanisms which are involved in the maintenance of homeostatic equilibrium of these networks are numerous, involving the regulation of genetic expression, growth factor secretion, signalling pathways, secondary messaging systems, and ion channel activity. However, many factors are capable of disrupting these pathways, which leads to an imbalance of homeostatic equilibrium. Ultimately, this leads to changes in the physical nature of skin, both functionally and cosmetically. Although various factors have been identified, including carcinogenesis, ultraviolet exposure, and mechanical stretching of skin, it was discovered that many of them affect similar components of regulatory pathways, such as fibroblasts, lysyl oxidase, and fibronectin. Additionally, it was discovered that the various regulatory pathways intersect with each other at various stages instead of working independently of each other. This review paper proposes a model which elucidates how these molecular pathways intersect with one another, and how various internal and external factors can disrupt these pathways, ultimately leading to a disruption in collagen and elastin networks.

/pdf/molecular-mechanisms-of-stress-responsive-changes-in-27n4lb5raa.pdf

Molecular Mechanisms of Stress-Responsive Changes in Collagen and Elastin Networks in Skin

Collagen self-assembly and the development of tendon mechanical properties.

Background/aims: The purpose of this work is to attempt to determine the elastic spring constant for collagen and elastic fibers (elastin) in skin and to detemine if the values of these elastic constants are similar to those reported for other tissues.

Methods: We studied the viscoelastic mechanical properties of human skin and dermis by measuring the incremental stress-strain behavior. Elastic stress-strain curves were used to obtain the elastic spring constant of elastin and collagen while the collagen fibril length was obtained from the slope of viscous stress-strain curves.

Results: Our results suggest that the elastic spring constant for elastin is about 4.0 MPa while that for collagen is about 4.4 GPa. The former value is similar to that calculated for ligamentum nuchae while the latter value is about 70% of the value found for tendon and self-assembled type I collagen fibers. The differences between the elastic constants for collagen molecules in tendon and skin is hypothesized to reflect the higher molecular tilt angle and lower D period found in skin compared to tendon as well as a shorter fibril length.

Conclusion: The differences in the collagen types present in skin and tendon may influence collagen self-assembly and the resulting viscoelastic properties.

Viscoelastic properties of human skin and processed dermis.

http://orion.bme.columbia.edu/lulab/pdf/Cooper-ACL1-2005.pdf

Fiber-based tissue-engineered scaffold for ligament replacement: design considerations and in vitro evaluation.

http://orion.bme.columbia.edu/lulab/pdf/LuHH-ACL2-2005.pdf

Joseph W. Freeman

Papers

Collagen self-assembly and the development of tendon mechanical properties.

Viscoelastic properties of human skin and processed dermis.

Fiber-based tissue-engineered scaffold for ligament replacement: design considerations and in vitro evaluation.

Anterior cruciate ligament regeneration using braided biodegradable scaffolds: in vitro optimization studies.

3D in vitro bioengineered tumors based on collagen I hydrogels