Eugene Bell Center for Regenerative Biology and Tissue Engineering

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https://hdl.handle.net/1912/4819

The ability of many animals to spontaneously regenerate their body parts has intrigued scientific observers for centuries. Although humans share the same basic genes and pathways, we have somehow lost these regenerative capacities, which leads to significant health costs. An understanding of tissue and organ regeneration in lower animals holds great promise for translating to medical treatments for serious human conditions, including spinal cord injury, diabetes, organ failure, and degenerative neural diseases such as Alzheimer’s.

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Browsing Eugene Bell Center for Regenerative Biology and Tissue Engineering by Subject "Aging"
  • Preprint
    Closing the wounds : one hundred and twenty five years of regenerative biology in the ascidian Ciona intestinalis
    ( 2014-06) Jeffery, William R.
    This year marks the 125th anniversary of the beginning of regeneration research in the ascidian Ciona intestinalis. A brief note was published in 1891 reporting the regeneration of the Ciona neural complex and siphons. This launched an active period of Ciona regeneration research culminating in the demonstration of partial body regeneration: the ability of proximal body parts to regenerate distal ones, but not vice versa. In a process resembling regeneration, wounds in the siphon tube were discovered to result in the formation of an ectopic siphon. Ciona regeneration research then lapsed into a period of relative inactivity following the purported demonstration of the inheritance of acquired characters using siphon regeneration as a model. Around the turn of the present century, Ciona regeneration research experienced a new blossoming. The current studies established the morphological and physiological integrity of the regeneration process and its resemblance to ontogeny. They also determined some of the cell types responsible for tissue and organ replacement and their sources in the body. Finally, they showed that regenerative capacity is reduced with age. Many other aspects of regeneration now can be studied at the mechanistic level because of the extensive molecular tools available in Ciona.
  • Article
    Distal regeneration involves the age dependent activity of branchial sac stem cells in the ascidian Ciona intestinalis
    (John Wiley & Sons, 2014-11-13) Jeffery, William R.
    Tunicates have high capacities for regeneration but the underlying mechanisms and their relationship to life cycle progression are not well understood. Here we investigate the regeneration of distal structures in the ascidian tunicate Ciona intestinalis. Analysis of regenerative potential along the proximal−distal body axis indicated that distal organs, such as the siphons, their pigmented sensory organs, and the neural complex, could only be replaced from body fragments containing the branchial sac. Distal regeneration involves the formation of a blastema composed of cells that undergo cell proliferation prior to differentiation and cells that differentiate without cell proliferation. Both cell types originate in the branchial sac and appear in the blastema at different times after distal injury. Whereas the branchial sac stem cells are present in young animals, they are depleted in old animals that have lost their regeneration capacity. Thus Ciona adults contain a population of age-related stem cells located in the branchial sac that are a source of precursors for distal body regeneration.
  • Preprint
    Regeneration, stem cells, and aging in the tunicate Ciona : insights from the oral siphon
    ( 2015-04) Jeffery, William R.
    Regeneration studies in the tunicate Ciona intestinalis have recently been focused on the potential of adult stem cells to replace injured tissues and organs during the adult life cycle using the oral siphon (OS) as a model. The OS has oral siphon pigment organs (OPO) along its rim and an underlying network of muscle fibers in its tube. Different regeneration processes are triggered by OS amputation at the tip, along the tube, or at the base. One process involves the replacement of OPO without new cell division by direct differentiation of locally deployed stem cells or stem cells that migrate from the branchial sac. Another process involves blastema formation by the migration of progenitor cells produced from branchial sac stem cells. The capacity for complete and accurate OS regeneration declines continuously during the adult life cycle. Finally, after an age threshold is reached, OS regeneration ceases in old animals. The loss of regeneration capacity in old animals involves the depletion of stem cells in the branchial sac, the inability of brachial sac progenitor cells to migrate to the sites of regeneration, and defective OPO replacement. The significance of the OS model for studying regeneration, stem cells, and aging will be enhanced by the application of molecular methods.