Wednesday, 19 September 2018

Hepatic Tissue Engineering :

The liver has over 500 functions, including protein, carbohydrate, and lipid metabolism; detoxification of endogenous and exogenous compounds; production of bile for digestion; and secretion of many serum proteins (i.e. albumin, coagulation factors). Each year, over 40,000 people die due to liver failure in the US alone, with over 2 million deaths estimated worldwide. Orthotopic liver transplantation is the only proven therapy for liver failure; however, there is a severe shortage of donor organs. Cell-based therapies have been proposed as an alternative to whole organ transplantation, as a temporary bridge to transplantation, and/or an adjunct to traditional therapies during liver regeneration. The three main approaches that have been proposed are: transplantation of isolated hepatocytes, implantable tissue-engineered constructs, and perfusion of blood through an extracorporeal bioartifical liver device containing parenchymal liver cells called hepatocytes. Despite significant investigations into each of these areas, progress has been stymied due to the propensity for isolated hepatocytes to rapidly lose viability and key liver-specific functions upon isolation from the native microenvironment of the liver.
Researchers have used microtechnology tools and biomaterials to synthesize 2D and 3D hepatic microenvironments to study determinants of cell fate and function and then perturb and interrogate these to model human disease. Researchers focused on (i) synthesizing human liver microenvironments for in vitro and in vivo interrogation and (ii) perturbing liver microenvironments with pathogens to model human disease. Some of the notable contributions include the discovery of small molecules that drive proliferation of adult hepatocytes and maturation of stem-cell derived progeny to enable sourcing of human hepatocytes, and the development of the first high-throughput model systems to study hepatotropic pathogens.

Saturday, 15 September 2018

Understanding interactions between Biomaterials and Biological systems using proteomics : 

The role that biomaterials play in the clinical treatment of damaged organs and tissues is changing. While biomaterials used in permanent medical devices were required to passively take over the function of a damaged tissue in the long term, current biomaterials are expected to trigger and harness the self-regenerative potential of the body in situ and then to degrade, the foundation of regenerative medicine. To meet these different requirements, it is imperative to fully understand the interactions biomaterials have with biological systems, in space and in time. This knowledge will lead to a better understanding of the regenerative capabilities of biomaterials aiding their design with improved functionalities (e.g. biocompatibility, bioactivity). Proteins play a pivotal role in the interaction between biomaterials and cells or tissues. Protein adsorption on the material surface is the very first event of this interaction, which is determinant for the subsequent processes of cell growth, differentiation, and extracellular matrix formation. Against this background, the aim of the current review is to provide insight in the current knowledge of the role of proteins in cell–biomaterial and tissue–biomaterial interactions. In particular, the focus is on proteomics studies, mainly using mass spectrometry, and the knowledge they have generated on protein adsorption of biomaterials, protein production by cells cultured on materials, safety and efficacy of new materials based on nanoparticles and the analysis of extracellular matrices and extracellular matrix–derived products. In the outlook, the potential and limitations of this approach are discussed and mass spectrometry imaging is presented as a powerful technique that complements existing mass spectrometry techniques by providing spatial molecular information about the material-biological system interactions.

Thursday, 6 September 2018

Magnesium and its alloys as Orthopedic Biomaterials : 

As a lightweight metal with mechanical properties similar to natural bone, a natural ionic presence with significant functional roles in biological systems, and in vivo degradation via corrosion in the electrolytic environment of the body, magnesium-based implants have the potential to serve as biocompatible, osteoconductive, degradable implants for load-bearing applications.
Current metallic biomaterials are essentially neutral in vivo, remaining as permanent fixtures, which in the case of plates, screws and pins used to secure serious fractures, must be removed by a second surgical procedure after the tissue has healed sufficiently. Repeat surgery increases costs to the health care system and further morbidity to the patient. Magnesium is an exceptionally lightweight metal. With a density of 1.74 g/cm3, magnesium is 1.6 and 4.5 times less dense than aluminium and steel, respectively. The fracture toughness of magnesium is greater than ceramic biomaterials such as hydroxyapatite, while the elastic modulus and compressive yield strength of magnesium are closer to those of natural bone than is the case for other commonly used metallic implants. Moreover, magnesium is essential to human metabolism and is naturally found in bone tissue.


Wednesday, 5 September 2018

Synthesis, properties, and biomedical applications of gelatin methacryloyl (GelMA) hydrogels : 

Gelatin methacryloyl (GelMA) hydrogels have been widely used for various biomedical applications due to their suitable biological properties and tunable physical characteristics. GelMA hydrogels closely resemble some essential properties of native extracellular matrix (ECM) due to the presence of cell-attaching and matrix metalloproteinase responsive peptide motifs, which allow cells to proliferate and spread in GelMA-based scaffolds. GelMA is also versatile from a processing perspective. It crosslinks when exposed to light irradiation to form hydrogels with tunable mechanical properties. It can also be microfabricated using different methodologies including micromolding, photomasking, bioprinting, self-assembly, and microfluidic techniques to generate constructs with controlled architectures. Hybrid hydrogel systems can also be formed by mixing GelMA with nanoparticles such as carbon nanotubes and graphene oxide, and other polymers to form networks with desired combined properties and characteristics for specific biological applications. Recent research has demonstrated the proficiency of GelMA-based hydrogels in a wide range of tissue engineering applications including engineering of bone, cartilage, cardiac, and vascular tissues, among others. Other applications of GelMA hydrogels, besides tissue engineering, include fundamental cell research, cell signaling, drug and gene delivery, and bio-sensing.



Monday, 3 September 2018

Biomaterials and Mesenchymal Stem Cells for Regenerative Medicine : 

The reconstruction of hard and soft tissues is a major challenge in regenerative medicine, since diseases or traumas are causing increasing numbers of tissue defects due to the aging of the population. Modern tissue engineering is increasingly using three-dimensional structured biomaterials in combination with stem cells as cell source, since mature cells are often not available in sufficient amounts or quality. Biomaterial scaffolds are developed that not only serve as cell carriers providing mechanical support, but actively influence cellular responses including cell attachment and proliferation. Chemical modifications such as the incorporation of chemotactic factors or cell adhesion molecules are examined for their ability to enhance tissue development successfully. E.g. growth factors have been investigated extensively as substances able to support cell growth, differentiation and angiogenesis. Thus, continuously new patents and studies are published, which are investigating the advantages and disadvantages of different biomaterials or cell types for the regeneration of specific tissues. The main focus on biomaterials, including natural and synthetic polymers, ceramics and corresponding composites used as scaffold materials to support cell proliferation and differentiation for hard and soft tissues regeneration. In addition, the local delivery of drugs by scaffold biomaterials.