{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture 17

Lecture 17 - BioE10 Lecture 17 Professor Irina Conboy...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: BioE10: Lecture 17 Professor Irina Conboy Forestalling aging through stem cell bioengineering g g g g g g December 29, 2008 Scientific American No Truth to the Fountain of Youth No anti-aging remedy on the market today has been proved effective. By S. Jay Olshansky, Leonard Hayflick and Bruce A. Carnes Editor's Note: We are reposting this essay from our June 2002 issue to accompany our coverage of The Curious Case of Benjamin Button. we think of aging as the accumulation of random damage to the building blocks of life—especially to DNA, certain proteins, carbohydrates and lipids (fats)... This damage gradually impairs the functioning of cells, tissues, organs and organ systems, thereby increasing vulnerability to disease and giving rise to the characteristic manifestations of aging, such as a loss of muscle and bone mass, a decline in reaction time, compromised hearing and vision, and b d li i i i i dh i d i i d reduced elasticity of the skin. Therefore, even if science could eliminate today’s leading killers of older individuals, i di id l aging would continue t occur, ensuring th t diff i ld ti to i that different t maladies would take their place. In addition, it would guarantee that one crucial body component or another—say, the cardiovascular system—would eventually experience a catastrophic failure. It is an inescapable biological reality that once the engine of life switches on, the body inevitably sows the seeds of its own destruction. Nature will always find the way to prove you wrong Don’t believe everything you think Don’t believe anything until it has been officially denied <40 years ~3 years <40 years ~400 years Experimental Hypothesis: Can we delay or even reverse the onset of tissue aging by boosting regenerative capacity of organ stem cells? Can we boost the regenerative capacity of organ stem cells by calibrating key g p y g y g y regulatory signal transduction networks to their “young” homeostatic signaling strength? Stem cells Stem cells Stem cells Stem cells 0---------------------------------------------100 0-------------------------------------2 Years of life on Earth Years of life on Earth Muscle atrophy, cataracts, less functional neurons, lack of immune responses, flare of cancers, obesity and diabetes, hair loss, bone loss… etc. Establishing the experimental system: 2000-2009 Basal lamina Satellite (stem) cell Laminin/PI Myonucleus y Niche Myofiber Plasma membrane Day 5 Day 1 Young Old O Conboy IM, et al 2002 Dev Cell Conboy IM, et al 2003 Science Conboy IM, et al 2003 Science Conboy IM, et al 2005 Nature Carlson and C b 2007 A i C ll C l d Conboy Aging Cell Carlson, Hsu and Conboy 2008 Nature O-Connor, Carlson and Conboy 2009 Biotechnology Progress Carlson, Conboy MJ, et al, 2009 EMBO MM Carlson, Conboy MJ, et al, 2009 Aging Cell Establishing the experimental system: 2002-2009 1st Enzymatic digestion and mechanical dissociation of myofibers, washes and sedimentation Leg muscle Contaminating intramuscular cells Myofibers+ M fib + Associated cells 2nd Enzymatic digestion and mechanical myofiber-associated cell dissociation washes and dissociation, sedimentation Myofibers Associated cells MACS to deplete leukocytes Basal lamina stripped myofiber Contaminating CD45+ leukocytes Highly enriched satellite cells eMyHC/BrdU/Hoechst BrdU B dU 2h GM GM SC Mb DM Mt Conboy IM, et al 2003 Science Sherwood, et al 2004 Cell Conboy IM et al 2005 Nature IM, Carlson and Conboy 2007 Aging Cell Carlson, Hsu and Conboy 2008 Nature O-Connor, Carlson and Conboy 2009 Biotechnology Progress Muscle stem cells are maintained in old mice and humans, but there is evolutionary-conserved age-specific decline in the regenerative capacity Mouse system Y O Conboy, et. al, 2003 Science Carlson, Hsu and Conboy 2008 Nature Human system Carlson Suetta, Conboy MJ, et al 2009 EMBO MM Core regulatory circuitry controlling myogenic cell fate Signalling networks regulating myogenic cell-fate cell fate Control +Wnt Delta/Notch Quiescent satellite cell Delta/Notch Activated satellite cell G0G1 Wnt Proliferating Myogenic progenitor it cells Numb Delta/Notch Day ~4 inact.GSK3 Wnt Numb Myoblasts y Myotubes Fusion and repair of the injury Conboy IM, et al 2002 Dev Cell Conboy IM, et al 2003 Science Conboy IM, t l C b IM et al 2005 N t Nature Conboy IM/Brack, et al 2008 Cell Stem Cell Carlson, Hsu and Conboy 2008 Nature Conboy lab unpublished Aging of signaling networks in myogenic niche. TGF-beta Delta/Notch Quiescent satellite cell 2008, Nature, 454:528 532. 2008 Nature 454:528‐532 G0G1 Activated satellite cell SF Chronicle, MIT technology review, BBC, German Public Radio, etc. Notch* Delta/Notch Wnt p15, p16, p21, p15 p16 p21 p27 pSmad3 TGF-Rcomplex p Delta/Notch Numb Notch Wnt Old niche Myoblasts Delta/injury cue Fusion and repair of the injury Young niche TGF- Experimental restoration of the Notch*/TGF- balance rejuvenates muscle repair Young trn control Old Smad 3 sh RNA Old control sh RNA 2008, Nature, 454:528‐532. ; Old trn control Forced activation of Notch also rejuvenates old muscle repair : Conboy IM, et al 2003 Science muscle repair : Conboy IM et al 2003 Science Systemic intervention for rejuvenated regeneration. Carlson, Conboy MJ, et al, 2009 Aging Cell My yogenic ca apacity Evolutionary conservation in muscle stem cell regulation and aging between short-lived, genetically identical mice that live in cages and eat the same food and long-lived genetically variable humans that have different life styles Carlson Suetta, Conboy MJ, et al 2009 EMBO MM Aging of signaling networks in human myogenic niche. TGF-beta MAPK/pERK Delta/Notch Quiescent satellite cell Activated satellite cell Delta/Notch Delta/Notch Numb G0G1 Wnt Wnt Myoblasts Fusion and repair of the injury Heterochronic parabiosis rejuvenates tissue repair: skeletal muscle, liver, neurogenesis and hematopietic system/HSCs. Bone marrow cells do not trans-differentiate into muscle satellite cells, brain or liver. , Organ stem cells persist in the old and have largely intact capacity for tissue repair. These cells are acutely inhibited by their aged organismal niches. For combating the age-specific regenerative decline one needs to identify and neutralize such inhibitory molecules. Same is required for successful transplantation therapies in older individuals. Conboy, et al, Nature 2005 Carlson, B. M. & Faulkner, J. A. Am. J. Physiol 256, (1989) Mike Conboy, Irv Weissman Aged circulation (blood sera) inhibits the regenerative responses of organ stem cells (such as satellite cells). This suggests that in heterochronic parabiosis the inhibitors introduced into common circulation by the aged mouse were removed or functionally neutralized by the y y y young p g partner. The inhibition by aged sera and rejuvenation by young sera are conserved between mouse and human. Mouse Human Aging C ll A i Cell, 2007 Nature, 2005 Nature, 2008, Aging Cell, 2009 Systemic TGF-1 is elevated with age in sera of mice and humans and inhibits muscle regeneration in a biphasic fashion. The levels even in young sera are inhibitory; attenuators of TGF- pathway are effective in rejuvenating tissue repair only when acting locally; TGF-1 is an inhibitor, but is not an endocrine inhibitor of regenerative capacity. y; , g p y Carlson, Conboy MJ, at al, 2009 Aging Cell Controlled calibration of stem cell niches for healthy, youthful tissue maintenance and repair Youthful (healthy) niche calibration in 3D Proteome analysis Organ stem cells Satellite cells express robust telomerase activity and can maintain telomeres throughout the life-span O'Connor, 2009 Biotechnology Progress Old muscle stem cells either avoid DNA damage or perform efficient repair Cellular metabolism t b li Replication errors Nucleases UV ligth Ionizing radiations di ti Chemicals base modifications nucleotide mismatch intra and inter strand crosslink single and double strand breaks Senescence or Apoptosis DNA repair Young Wendy Cousin; Say Tar Goh Old NIH/NIA; CIRM; Glenn Foundation , SCRF, MJFF, EMF Thanks!!! Conclusions: Stem cells in old organ have largely intact capacity for tissue Dr. Morgan Carlson repair, but are acutely inhibited by the aged systemic and local Dr. Mike Conboy organ niches, which moreover, is conserved between mice and Haroldo Silva humans Dr. Matthew O’Connor Eric Jabart Notch promotes myogenic cell expansion, Wnt promotes myogenic Swomitra Mohanty differentiation (into myoblasts and myotubes) myotubes). Lydia S h L di Sohn John Wang (URAP) Laurel Barchas (URAP) TGF- is an age-specific evolutionary-conserved inhibitory culprit Say Tar Goh (HAAS) (TGF- is antagonized by active Notch in young, but not in old Dr. Michael Hsu niches). Dr. Jaemin Jeong Dr. Preeti Palival; Youthful pathway strength promotes youthful stem cell responses Dr. Wendy Cousin Dr. Christian Elabd Satellite cell telomerase activity or DNA repair are not extinguished Nicole Higashiyama (URAP) by the aging process. Rajiv Desai If we boost the regenerative capacity of aged organs, will this delay or possibly reverse the onset of aging? Pending IPs: 1). Self-Attenuating Circuitry For Stabilizing TGF-b/pSMAD and Notch Homostasis and for Recalibration of Regeneration-Specific Pathways in Stem Cells. 2). Biochemically-defined self-assembly of muscle fibers with associated stem cells from initially equivalent primary progenitor cultures. 3). Orchestration of tissue and organ repair by controlling behaviour of endogenous stem and progenitor cells. ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online