Tissue engineering is a biomedical engineering discipline that uses a combination of cells, engineering, materials methods, and suitable biochemical and physicochemical factors to restore, maintain, improve, or replace different types of biological tissues. Tissue engineering often involves the use of cells placed on tissue scaffolds in the formation of new viable tissue for a medical purpose, but is not limited to applications involving cells and tissue scaffolds. While it was once categorized as a sub-field of biomaterials, having grown in scope and importance, it can is considered as a field of its own.
Cell therapy is a therapy in which viable cells are injected, grafted or implanted into a patient in order to effectuate a medicinal effect, for example, by transplanting T-cells capable of fighting cancer cells via cell-mediated immunity in the course of immunotherapy, or grafting stem cells to regenerate diseased tissues.
Matrigel is the trade name for the solubilized basement membrane matrix secreted by Engelbreth-Holm-Swarm (EHS) mouse sarcoma cells produced by Corning Life Sciences. Matrigel resembles the laminin/collagen IV-rich basement membrane extracellular environment found in many tissues and is used by cell biologists as a substrate for culturing cells.
In cardiology neocardiogenesis is the homeostatic regeneration, repair and renewal of sections of malfunctioning adult cardiovascular tissue. This includes a combination of cardiomyogenesis and angiogenesis.
Nano-scaffolding or nanoscaffolding is a medical process used to regrow tissue and bone, including limbs and organs. The nano-scaffold is a three-dimensional structure composed of polymer fibers very small that are scaled from a Nanometer scale. Developed by the American military, the medical technology uses a microscopic apparatus made of fine polymer fibers called a scaffold. Damaged cells grip to the scaffold and begin to rebuild missing bone and tissue through tiny holes in the scaffold. As tissue grows, the scaffold is absorbed into the body and disappears completely.
Arginylglycylaspartic acid (RGD) is the most common peptide motif responsible for cell adhesion to the extracellular matrix (ECM), found in species ranging from Drosophila to humans. Cell adhesion proteins called integrins recognize and bind to this sequence, which is found within many matrix proteins, including fibronectin, fibrinogen, vitronectin, osteopontin, and several other adhesive extracellular matrix proteins. The discovery of RGD and elucidation of how RGD binds to integrins has led to the development of a number of drugs and diagnostics, while the peptide itself is used ubiquitously in bioengineering. Depending on the application and the integrin targeted, RGD can be chemically modified or replaced by a similar peptide which promotes cell adhesion.
Cellular cardiomyoplasty, or cell-based cardiac repair, is a new potential therapeutic modality in which progenitor cells are used to repair regions of damaged or necrotic myocardium. The ability of transplanted progenitor cells to improve function within the failing heart has been shown in experimental animal models and in some human clinical trials. In November 2011, a large group of collaborators at Minneapolis Heart Institute Foundation at Abbott Northwestern found no significant difference in left ventricular ejection fraction (LVEF) or other markers, between a group of patients treated with cellular cardiomyoplasty and a group of control patients. In this study, all patients were post MI, post percutaneous coronary intervention (PCI) and that infusion of progenitor cells occurred 2–3 weeks after intervention. In a study that is currently underway, however, more positive results were being reported: In the SCIPIO trial, patients treated with autologous cardiac stem cells post MI have been reported to be showing statistically significant increases in LVEF and reduction in infarct size over the control group at four months after implant. Positive results at the one-year mark are even more pronounced. Yet the SCIPIO trial "was recently called into question". Harvard University is "now investigating the integrity of some of the data". The Lancet recently published a non-specific ‘Expression of concern’ about the paper. Subsequently, another preclinical study also raised doubts on the rationale behind using this special kind of cell, as it was found that the special cells only have a minimal ability in generating new cardiomyocytes. Some specialists therefore now raise concerns to continue.
Heart nanotechnology is the "Engineering of functional systems at the molecular scale".
The Network of Excellence for Functional Biomaterials (NFB) is a multidisciplinary research centre which hosts over sixty biologists, chemists, scientists, engineers and clinicians. It is based at the National University of Ireland, Galway, and is directed by Professor Abhay Pandit.
Endogenous cardiac stem cells (eCSCs) are tissue-specific stem progenitor cells harboured within the adult mammalian heart. It has to be noted that a scientific-misconduct scandal, involving Harvard professor Piero Anversa, might indicate that the heart stem cell concept be broken. Therefore, the following article should be read with caution, as it builds on Anversa's results.
Human HGF plasmid DNA therapy of cardiomyocytes is being examined as a potential treatment for coronary artery disease, as well as treatment for the damage that occurs to the heart after MI. After MI, the myocardium suffers from reperfusion injury which leads to death of cardiomyocytes and detrimental remodelling of the heart, consequently reducing proper cardiac function. Transfection of cardiac myocytes with human HGF reduces ischemic reperfusion injury after MI. The benefits of HGF therapy include preventing improper remodelling of the heart and ameliorating heart dysfunction post-MI.
The in vivo bioreactor is a tissue engineering paradigm that uses bioreactor methodology to grow neotissue in vivo that augments or replaces malfunctioning native tissue. Tissue engineering principles are used to construct a confined, artificial bioreactor space in vivo that hosts a tissue scaffold and key biomolecules necessary for neotissue growth. Said space often requires inoculation with pluripotent or specific stem cells to encourage initial growth, and access to a blood source. A blood source allows for recruitment of stem cells from the body alongside nutrient delivery for continual growth. This delivery of cells and nutrients to the bioreactor eventually results in the formation of a neotissue product.
Human engineered cardiac tissues (hECTs) are derived by experimental manipulation of pluripotent stem cells, such as human embryonic stem cells (hESCs) and, more recently, human induced pluripotent stem cells (hiPSCs) to differentiate into human cardiomyocytes. Interest in these bioengineered cardiac tissues has risen due to their potential use in cardiovascular research and clinical therapies. These tissues provide a unique in vitro model to study cardiac physiology with a species-specific advantage over cultured animal cells in experimental studies. hECTs also have therapeutic potential for in vivo regeneration of heart muscle. hECTs provide a valuable resource to reproduce the normal development of human heart tissue, understand the development of human cardiovascular disease (CVD), and may lead to engineered tissue-based therapies for CVD patients.
A bioartificial heart is an engineered heart that contains the extracellular structure of a decellularized heart and cellular components from a different source. Such hearts are of particular interest for therapy as well as research into heart disease. The first bioartificial hearts were created in 2008 using cadaveric rat hearts. In 2014, human-sized bioartificial pig hearts were constructed. Bioartificial hearts have not been developed yet for clinical use, although the recellularization of porcine hearts with human cells opens the door to xenotransplantation.
Fujifilm Cellular Dynamics, Inc. (FCDI) is a large scale manufacturer of human cells, created from induced pluripotent stem cells, for use in basic research, drug discovery and regenerative medicine applications.
Muscle tissue engineering is a subset of the general field of tissue engineering, which studies the combined use of cells and scaffolds to design therapeutic tissue implants. Within the clinical setting, muscle tissue engineering involves the culturing of cells from the patient's own body or from a donor, development of muscle tissue with or without the use of scaffolds, then the insertion of functional muscle tissue into the patient's body. Ideally, this implantation results in full regeneration of function and aesthetic within the patient's body. Outside the clinical setting, muscle tissue engineering is involved in drug screening, hybrid mechanical muscle actuators, robotic devices, and the development of engineered meat as a new food source.
Regeneration in humans is the regrowth of lost tissues or organs in response to injury. This is in contrast to wound healing, or partial regeneration, which involves closing up the injury site with some gradation of scar tissue. Some tissues such as skin, the vas deferens, and large organs including the liver can regrow quite readily, while others have been thought to have little or no capacity for regeneration following an injury.
Tissue engineered heart valves (TEHV) offer a new and advancing proposed treatment of creating a living heart valve for people who are in need of either a full or partial heart valve replacement. Currently, there are over a quarter of a million prosthetic heart valves implanted annually, and the number of patients requiring replacement surgeries is only suspected to rise and even triple over the next fifty years. While current treatments offered such as mechanical valves or biological valves are not deleterious to one's health, they both have their own limitations in that mechanical valves necessitate the lifelong use of anticoagulants while biological valves are susceptible to structural degradation and reoperation. Thus, in situ (in its original position or place) tissue engineering of heart valves serves as a novel approach that explores the use creating a living heart valve composed of the host's own cells that is capable of growing, adapting, and interacting within the human body's biological system.
Cultrex Basement Membrane Extract (BME) is the trade name for a extracellular protein mixture secreted by Engelbreth-Holm-Swarm (EHS) mouse sarcoma cells and manufactured into a hydrogel by R&D Systems, a brand of Bio-Techne. Similar to Matrigel, this hydrogel is a natural extracellular matrix that mimics the complex extracellular environment within complex tissues. It is used as a general cell culture substrate across a wide variety of research applications.
Milica Radisic is a Serbian Canadian tissue engineer, academic and researcher. She is a professor at the University of Toronto’s Institute of Biomaterials and Biomedical Engineering, and the Department of Chemical Engineering and Applied Chemistry. She co-founded TARA Biosystems and is a senior scientist at the Toronto General Hospital Research Institute.
