Regeneration in humans
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.
Other organs and body parts that have been procured to regenerate include: penis, fats, vagina, brain tissue, thymus, and a scaled down human heart.
Whilst by 2016, regeneration by 3D printing had been generally operationalised by in vitro (inside the lab) in order to be built and prepare tissue for transplantation.
[1] In 2021, more people were paying attention to the possibility of scar free healing alongside new technologies involving instruments.
[4] In 1949, a much more pure form of insulin was, instead of causing lipoatrophy, shown to regenerate the localised loss of fat after injections in to diabetics.
[5] In 1976, the regenerative response was shown to work in a non-diabetic after a 3 x 3 cm lipoatrophic arm scar was treated with pure monocomponent porcine soluble insulin.
[20] Scientists found leprosy-causing bacteria viably regenerate and rejuvenate the liver in its armadillos hosts, which may enable novel human therapies based on knowledge or components gained from naturally evolved organisms or capabilities.
[21][22] Cardiomyocyte necrosis activates an inflammatory response that serves to clear the injured myocardium from dead cells, and stimulates repair, but may also extend injury.
A house surgeon in the Montreal General Hospital underwent amputation of the distal phalanx to stop the spread of an infection.
[27] Studies in the 1970s showed that children up to the age of 10 or so who lose fingertips in accidents can regrow the tip of the digit within a month provided their wounds are not sealed up with flaps of skin – the de facto treatment in such emergencies.
[28][29] In August 2005, Lee Spievack, then in his early sixties, accidentally sliced off the tip of his right middle finger just above the first phalanx.
His brother, Dr. Alan Spievack, was researching regeneration and provided him with powdered extracellular matrix, developed by Dr. Stephen Badylak of the McGowan Institute of Regenerative Medicine.
Ben Goldacre has described this as "the missing finger that never was", claiming that fingertips regrow and quoted Simon Kay, professor of hand surgery at the University of Leeds, who from the picture provided by Goldacre described the case as seemingly "an ordinary fingertip injury with quite unremarkable healing"[31] A similar story was reported by CNN.
Her personal research and consultation with several specialists including Badylak eventually resulted in her undergoing regenerative therapy and regaining her fingertip.
[33] The basic functional and structural unit of the kidney is nephron, which is mainly composed of four components: the glomerulus, tubules, the collecting duct and peritubular capillaries.
Following an acute injury, the proximal tubule is damaged more, and the injured epithelial cells slough off the basement membrane of the nephron.
[citation needed] The human liver is particularly known for its ability to regenerate, and is capable of doing so from only one quarter of its tissue,[35] due chiefly to the unipotency of hepatocytes.
Many fall under the topic of regenerative medicine, which includes the methods and research conducted with the aim of regenerating the organs and tissues of humans as a result of injury.
[4][5] During a high-fat diet, and during hair follicle growth, mature adipocytes (fats) are naturally formed in multiple tissues.
[43][42] Scientists also identified bone morphogenetic protein (BMP) signalling as important for myofibroblasts transforming into adipocytes for the purpose of skin and fat regeneration.
[46] The scarring that results is then responsible for greatly increasing the risk of life-threatening abnormal heart rhythms or arrhythmias.
[citation needed] Despite the earlier belief that human cardiomyocytes are not generated later in life, a recent study has found that this is not the case.
This study took advantage of the nuclear bomb testing and other radioactive sources during the Atomic Age which introduced carbon-14 into the atmosphere (essentially all of which had decayed up to that point in Earth's history) and therefore into the cells of biologically active inhabitants.
Masumoto and his team designed a method of producing sheets of cardiomyocytes and vascular cells from human iPSCs.
Tissue-engineered heart valves derived from human cells have been created in vitro and transplanted into a non-human primate model.
These showed a promising amount of cellular repopulation even after eight weeks, and succeeded in outperforming currently-used non-biological valves.
[63] Cystic fibrosis is another disease of the lungs, which is highly fatal and genetically linked to a mutation in the CFTR gene.
[15] A goal of spinal cord injury research is to promote neuroregeneration, reconnection of damaged neural circuits.
Researchers from the University of Edinburgh have succeeded in regenerating a living organ that closely resembles a juvenile thymus in terms of structure and gene expression profile.
