Regenerative medicine is a branch of translational research[1] in tissue engineering and molecular biology which deals with the "process of replacing, engineering or regenerating human cells, tissues or organs to restore or establish normal function".[2] This field holds the promise of engineering damaged tissues and organs via stimulating the body's own repair mechanisms to functionally heal previously irreparable tissues or organs.[3]

Regenerative medicine also includes the possibility of growing tissues and organs in the laboratory and safely implanting them when the body cannot heal itself. If a regenerated organ's cells would be derived from the patient's own tissue or cells, this would potentially solve the problem of the shortage of organs available for donation, and the problem of organ transplant rejection.[4][5][6]

Attributed to William Haseltine (founder of Human Genome Sciences),[7] the term "regenerative medicine" was first found in a 1992 article on hospital administration by Leland Kaiser. Kaisers paper closes with a series of short paragraphs on future technologies that will impact hospitals. One paragraph had Regenerative Medicine as a bold print title and stated, A new branch of medicine will develop that attempts to change the course of chronic disease and in many instances will regenerate tired and failing organ systems.[8][9]

Regenerative medicine refers to a group of biomedical approaches to clinical therapies that may involve the use of stem cells.[10] Examples include the injection of stem cells or progenitor cells obtained through Directed differentiation (cell therapies); the induction of regeneration by biologically active molecules administered alone or as a secretion by infused cells (immunomodulation therapy); and transplantation of in vitro grown organs and tissues (tissue engineering).[11][12]

From 1995 to 1998 Michael D. West, PhD, organized and managed the research between Geron Corporation and its academic collaborators James Thomson at the University of Wisconsin-Madison and John Gearhart of Johns Hopkins University that led to the first isolation of human embryonic stem and human embryonic germ cells.[13]

Dr. Stephen Badylak, a Research Professor in the Department of Surgery and director of Tissue Engineering at the McGowan Institute for Regenerative Medicine at the University of Pittsburgh, developed a process for scraping cells from the lining of a pig's bladder, decellularizing (removing cells to leave a clean extracellular structure) the tissue and then drying it to become a sheet or a powder. This extracellular matrix powder was used to regrow the finger of Lee Spievak, who had severed half an inch of his finger after getting it caught in a propeller of a model plane.[14][15][16][dubious discuss] As of 2011, this new technology is being employed by the military on U.S. war veterans in Texas, as well as for some civilian patients. Nicknamed "pixie-dust," the powdered extracellular matrix is being used to successfully regenerate tissue lost and damaged due to traumatic injuries.[17]

In June 2008, at the Hospital Clnic de Barcelona, Professor Paolo Macchiarini and his team, of the University of Barcelona, performed the first tissue engineered trachea (wind pipe) transplantation. Adult stem cells were extracted from the patient's bone marrow, grown into a large population, and matured into cartilage cells, or chondrocytes, using an adaptive method originally devised for treating osteoarthritis. The team then seeded the newly grown chondrocytes, as well as epithileal cells, into a decellularised (free of donor cells) tracheal segment that was donated from a 51 year old transplant donor who had died of cerebral hemorrhage. After four days of seeding, the graft was used to replace the patient's left main bronchus. After one month, a biopsy elicited local bleeding, indicating that the blood vessels had already grown back successfully.[18][19]

In 2009 the SENS Foundation was launched, with its stated aim as "the application of regenerative medicine defined to include the repair of living cells and extracellular material in situ to the diseases and disabilities of ageing." [20]

In 2012, Professor Paolo Macchiarini and his team improved upon the 2008 implant by transplanting a laboratory-made trachea seeded with the patient's own cells.[21]

On Sep 12, 2014, surgeons at the Institute of Biomedical Research and Innovation Hospital in Kobe, Japan, transplanted a 1.3 by 3.0 millimeter sheet of retinal pigment epithelium cells, which were differentiated from iPS cells through Directed differentiation, into an eye of an elderly woman, who suffers from age-related macular degeneration.[22]

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Regenerative medicine - Wikipedia, the free encyclopedia

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