mtDNA copy number: molecular diagnostics and mitochondrial-nuclear crosstalk in frailty and ageing

C. G. Ward

doi:10.14739/2310-1237.2025.2.338006

Authors

C. G. Ward Medical University of Gdańsk, Poland

DOI:

https://doi.org/10.14739/2310-1237.2025.2.338006

Keywords:

ageing, mtDNA, copy-number, fusion-fission, OXPHOS, ROS, Sirtuins, Klotho

Abstract

Quantitative assessment of mitochondrial DNA copy number is an emerging field of study in the diagnosis and evaluation of age-related pathology and frailty in the elderly, along with the assessment of other acute and chronic diseases that are often necessary within this patient cohort.

Aim: to analyze current advances in the quantitative assessment of mitochondrial DNA copy number as a tool for diagnosing and evaluating age-related pathology, frailty, and comorbid conditions in the elderly.

Material and methods. The author independently conducted a thorough review of literature available from the NIH, PubMed database, providing a detailed narrative of updates in the field. As clinical trials seek to further develop practical techniques, the author then undertook a search of relevant trials at ClinicalTrials.gov, including this as a table in the body text.

Results. The review provides a thorough examination of the theoretical foundation of mitochondrial biogenesis, fusion-fission processes, and control and repair of mitochondrial genetic material, and how advances in these topics may be applied to better understand the processes being measured in quantitative mitochondrial DNA analysis.

Conclusions. Detailed examination of the crosstalk between mitochondrial control proteins and nuclear factors, and the fundamental role of energy homeostasis apparatus within ageing processes underpins the advances in translational aspects of mitochondrial medicine and allows more effective exploitation of this emerging field.

Author Biography

C. G. Ward, Medical University of Gdańsk

Collegium Biomedicum

References

Ernster L, Low H, Nordenbrand K, Ernster B. A component promoting oxidative phosphorylation, released from mitochondria during aging. Exp Cell Res. 1955;9(2):348-9. doi: https://doi.org/10.1016/0014-4827(55)90108-7

Trifunovic A, Wredenberg A, Falkenberg M, Spelbrink JN, Rovio AT, Bruder CE, et al. Premature ageing in mice expressing defective mitochondrial DNA polymerase. Nature. 2004;429(6990):417-23. doi: https://doi.org/10.1038/nature02517

Folstein MF, Folstein SE, McHugh PR. "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12(3):189-98. doi: https://doi.org/10.1016/0022-3956(75)90026-6

Fried LP, Tangen CM, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci. 2001;56(3):M146-56. doi: https://doi.org/10.1093/gerona/56.3.m146

Chew J, Tay L, Lim JP, Leung BP, Yeo A, Yew S, et al. Serum Myostatin and IGF-1 as Gender-Specific Biomarkers of Frailty and Low Muscle Mass in Community-Dwelling Older Adults. J Nutr Health Aging. 2019;23(10):979-86. doi: https://doi.org/10.1007/s12603-019-1255-1

Doi T, Shimada H, Makizako H, Tsutsumimoto K, Hotta R, Nakakubo S, et al. Association of insulin-like growth factor-1 with mild cognitive impairment and slow gait speed. Neurobiol Aging. 2015;36(2):942-7. doi: https://doi.org/10.1016/j.neurobiolaging.2014.10.035

Cardoso AL, Fernandes A, Aguilar-Pimentel JA, de Angelis MH, Guedes JR, Brito MA, et al. Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases. Ageing Res Rev. 2018;47:214-77. doi: https://doi.org/10.1016/j.arr.2018.07.004

Cawthon PM, Ensrud KE, Laughlin GA, Cauley JA, Dam TT, Barrett-Connor E, et al. Sex hormones and frailty in older men: the osteoporotic fractures in men (MrOS) study. J Clin Endocrinol Metab. 2009;94(10):3806-15. doi: https://doi.org/10.1210/jc.2009-0417

Doi T, Makizako H, Tsutsumimoto K, Hotta R, Nakakubo S, Makino K, et al. Association between Insulin-Like Growth Factor-1 and Frailty among Older Adults. J Nutr Health Aging. 2018;22(1):68-72. doi: https://doi.org/10.1007/s12603-017-0916-1

Clegg A, Young J, Iliffe S, Rikkert MO, Rockwood K. Frailty in elderly people. Lancet. 2013;381(9868):752-62. doi: https://doi.org/10.1016/S0140-6736(12)62167-9

Gonçalves RS, Maciel ÁC, Rolland Y, Vellas B, de Souto Barreto P. Frailty biomarkers under the perspective of geroscience: A narrative review. Ageing Res Rev. 2022;81:101737. doi: https://doi.org/10.1016/j.arr.2022.101737

Dubińska-Magiera M, Jabłońska J, Saczko J, Kulbacka J, Jagla T, Daczewska M. Contribution of small heat shock proteins to muscle development and function. FEBS Lett. 2014;588(4):517-30. doi: https://doi.org/10.1016/j.febslet.2014.01.005

Grant JE, Bradshaw AD, Schwacke JH, Baicu CF, Zile MR, Schey KL. Quantification of protein expression changes in the aging left ventricle of Rattus norvegicus. J Proteome Res. 2009;8(9):4252-63. doi: https://doi.org/10.1021/pr900297f

Elemam NM, Talaat IM, Maghazachi AA. CXCL10 Chemokine: A Critical Player in RNA and DNA Viral Infections. Viruses. 2022;14(11):2445. doi: https://doi.org/10.3390/v14112445

Zhang N, Zhao YD, Wang XM. CXCL10 an important chemokine associated with cytokine storm in COVID-19 infected patients. Eur Rev Med Pharmacol Sci. 2020;24(13):7497-505. doi: https://doi.org/10.26355/eurrev_202007_21922

Lee EY, Lee ZH, Song YW. CXCL10 and autoimmune diseases. Autoimmun Rev. 2009;8(5):379-83. doi: https://doi.org/10.1016/j.autrev.2008.12.002

Tokunaga R, Zhang W, Naseem M, Puccini A, Berger MD, Soni S, et al. CXCL9, CXCL10, CXCL11/CXCR3 axis for immune activation - A target for novel cancer therapy. Cancer Treat Rev. 2018;63:40-7. doi: https://doi.org/10.1016/j.ctrv.2017.11.007

Saul D, Kosinsky RL. Epigenetics of Aging and Aging-Associated Diseases. Int J Mol Sci. 2021;22(1):401. doi: https://doi.org/10.3390/ijms22010401

Longchamps RJ, Castellani CA, Yang SY, Newcomb CE, Sumpter JA, Lane J, et al. Evaluation of mitochondrial DNA copy number estimation techniques. PLoS One. 2020;15(1):e0228166. doi: https://doi.org/10.1371/journal.pone.0228166

Picard M. Blood mitochondrial DNA copy number: What are we counting? Mitochondrion. 2021;60:1-11. doi: https://doi.org/10.1016/j.mito.2021.06.010

Wai T, Ao A, Zhang X, Cyr D, Dufort D, Shoubridge EA. The role of mitochondrial DNA copy number in mammalian fertility. Biol Reprod. 2010;83(1):52-62. doi: https://doi.org/10.1095/biolreprod.109.080887

Kushnir VA, Ludaway T, Russ RB, Fields EJ, Koczor C, Lewis W. Reproductive aging is associated with decreased mitochondrial abundance and altered structure in murine oocytes. J Assist Reprod Genet. 2012;29(7):637-42. doi: https://doi.org/10.1007/s10815-012-9771-5

Wang T, Zhang M, Jiang Z, Seli E. Mitochondrial dysfunction and ovarian aging. Am J Reprod Immunol. 2017;77(5). doi: https://doi.org/10.1111/aji.12651

McCastlain K, Howell CR, Welsh CE, Wang Z, Wilson CL, Mulder HL, et al. The Association of Mitochondrial Copy Number With Sarcopenia in Adult Survivors of Childhood Cancer. J Natl Cancer Inst. 2021;113(11):1570-580. doi: https://doi.org/10.1093/jnci/djab084

Reddy, P.H. Monzio Compagnoni G, Di Fonzo A, Corti S, Comi GP, Bresolin N, et al. The Role of Mitochondria in Neurodegenerative Diseases: the Lesson from Alzheimer's Disease and Parkinson's Disease. Mol Neurobiol. 2020;57(7):2959-80. doi: https://doi.org/10.1007/s12035-020-01926-1

Yang SY, Castellani CA, Longchamps RJ, Pillalamarri VK, O'Rourke B, Guallar E, et al. Blood-derived mitochondrial DNA copy number is associated with gene expression across multiple tissues and is predictive for incident neurodegenerative disease. Genome Res. 2021;31(3):349-58. doi: https://doi.org/10.1101/gr.269381.120

Ashar FN, Moes A, Moore AZ, Grove ML, Chaves PH, Coresh J, et al. Association of mitochondrial DNA levels with frailty and all-cause mortality. J Mol Med (Berl). 2015;93(2):177-86. doi: https://doi.org/10.1007/s00109-014-1233-3

Lee JW, Park KD, Im JA, Kim MY, Lee DC. Mitochondrial DNA copy number in peripheral blood is associated with cognitive function in apparently healthy elderly women. Clin Chim Acta. 2010;411(7-8):592-6. doi: https://doi.org/10.1016/j.cca.2010.01.024

Ubaida-Mohien C, Spendiff S, Lyashkov A, Moaddel R, MacMillan NJ, Filion ME, et al. Unbiased proteomics, histochemistry, and mitochondrial DNA copy number reveal better mitochondrial health in muscle of high-functioning octogenarians. Elife. 2022;11:e74335. doi: https://doi.org/10.7554/eLife.74335

Mengel-From J, Thinggaard M, Dalgård C, Kyvik KO, Christensen K, Christiansen L. Mitochondrial DNA copy number in peripheral blood cells declines with age and is associated with general health among elderly. Hum Genet. 2014;133(9):1149-59. doi: https://doi.org/10.1007/s00439-014-1458-9

Rao M, Jaber BL, Balakrishnan VS. Chronic kidney disease and acquired mitochondrial myopathy. Curr Opin Nephrol Hypertens. 2018;27(2):113-20. doi: https://doi.org/10.1097/MNH.0000000000000393

Tin A, Grams ME, Ashar FN, Lane JA, Rosenberg AZ, Grove ML, et al. Association between Mitochondrial DNA Copy Number in Peripheral Blood and Incident CKD in the Atherosclerosis Risk in Communities Study. J Am Soc Nephrol. 2016;27(8):2467-73. doi: https://doi.org/10.1681/ASN.2015060661

Itoh K, Weis S, Mehraein P, Müller-Höcker J. Cytochrome c oxidase defects of the human substantia nigra in normal aging. Neurobiol Aging. 1996;17(6):843-8. doi: https://doi.org/10.1016/s0197-4580(96)00168-6

Kraytsberg Y, Kudryavtseva E, McKee AC, Geula C, Kowall NW, Khrapko K. Mitochondrial DNA deletions are abundant and cause functional impairment in aged human substantia nigra neurons. Nat Genet. 2006;38(5):518-20. doi: https://doi.org/10.1038/ng1778

Wakabayashi T. Megamitochondria formation - physiology and pathology. J Cell Mol Med. 2002;6(4):497-538. doi: https://doi.org/10.1111/j.1582-4934.2002.tb00452.x

Wakabayashi T. Structural changes of mitochondria related to apoptosis: swelling and megamitochondria formation. Acta Biochim Pol. 1999;46(2):223-37.

Wakabayashi T, Spodnik JH. Structural changes of mitochondria during free radical-induced apoptosis. Folia Morphol (Warsz). 2000;59(2):61-75.

Iqbal S, Ostojic O, Singh K, Joseph AM, Hood DA. Expression of mitochondrial fission and fusion regulatory proteins in skeletal muscle during chronic use and disuse. Muscle Nerve. 2013;48(6):963-70. doi: https://doi.org/10.1002/mus.23838

Adebayo M, Singh S, Singh AP, Dasgupta S. Mitochondrial fusion and fission: The fine-tune balance for cellular homeostasis. FASEB J. 2021;35(6):e21620. doi: https://doi.org/10.1096/fj.202100067R

Rahman S. Leigh syndrome. Handb Clin Neurol. 2023;194:43-63. doi: https://doi.org/10.1016/B978-0-12-821751-1.00015-4

Schubert Baldo M, Vilarinho L. Molecular basis of Leigh syndrome: a current look. Orphanet J Rare Dis. 2020;15(1):31. doi: https://doi.org/10.1186/s13023-020-1297-9. Erratum in: Orphanet J Rare Dis. 2020;15(1):77. doi: https://doi.org/10.1186/s13023-020-1351-7

Sidarala V, Zhu J, Levi-D'Ancona E, Pearson GL, Reck EC, Walker EM, et al. Mitofusin 1 and 2 regulation of mitochondrial DNA content is a critical determinant of glucose homeostasis. Nat Commun. 2022;13(1):2340. doi: https://doi.org/10.1038/s41467-022-29945-7

de Brito OM, Scorrano L. Mitofusin 2 tethers endoplasmic reticulum to mitochondria. Nature. 2008;456(7222):605-10. doi: https://doi.org/10.1038/nature07534. Erratum in: Nature. 2014;513(7517):266.

Huang K, Pei S, Sun Y, Xu X, Fang Y, Lai M, et al. Mitofusin 1-Mediated Redistribution of Mitochondrial Antiviral Signaling Protein Promotes Type 1 Interferon Response in Human Cytomegalovirus Infection. Microbiol Spectr. 2023;11(2):e0461522. doi: https://doi.org/10.1128/spectrum.04615-22

Deretic V, Levine B. Autophagy balances inflammation in innate immunity. Autophagy. 2018;14(2):243-51. doi: https://doi.org/10.1080/15548627.2017.1402992

VanderVeen BN, Fix DK, Carson JA. Disrupted Skeletal Muscle Mitochondrial Dynamics, Mitophagy, and Biogenesis during Cancer Cachexia: A Role for Inflammation. Oxid Med Cell Longev. 2017;2017:3292087. doi: https://doi.org/10.1155/2017/3292087

Fix DK, VanderVeen BN, Counts BR, Carson JA. Regulation of Skeletal Muscle DRP-1 and FIS-1 Protein Expression by IL-6 Signaling. Oxid Med Cell Longev. 2019;2019:8908457. doi: https://doi.org/10.1155/2019/8908457

Dröge W. Oxidative aging and insulin receptor signaling. J Gerontol A Biol Sci Med Sci. 2005;60(11):1378-85. doi: https://doi.org/10.1093/gerona/60.11.1378

Dröge W, Kinscherf R. Aberrant insulin receptor signaling and amino acid homeostasis as a major cause of oxidative stress in aging. Antioxid Redox Signal. 2008;10(4):661-78. doi: https://doi.org/10.1089/ars.2007.1953

Lee WS, Kim J. Insulin-like growth factor-1 signaling in cardiac aging. Biochim Biophys Acta Mol Basis Dis. 2018;1864(5 Pt B):1931-8. doi: https://doi.org/10.1016/j.bbadis.2017.08.029

Goodman EK, Mitchell CS, Teo JD, Gladding JM, Abbott KN, Rafiei N, et al. The effect of insulin receptor deletion in neuropeptide Y neurons on hippocampal dependent cognitive function in aging mice. J Integr Neurosci. 2022;21(1):6. doi: https://doi.org/10.31083/j.jin2101006

He J, Mao CC, Reyes A, Sembongi H, Di Re M, Granycome C, et al. The AAA+ protein ATAD3 has displacement loop binding properties and is involved in mitochondrial nucleoid organization. J Cell Biol. 2007;176(2):141-6. doi: https://doi.org/10.1083/jcb.200609158

Spelbrink JN, Li FY, Tiranti V, Nikali K, Yuan QP, Tariq M, et al. Human mitochondrial DNA deletions associated with mutations in the gene encoding Twinkle, a phage T7 gene 4-like protein localized in mitochondria. Nat Genet. 2001;28(3):223-31. doi: https://doi.org/10.1038/90058. Erratum in: Nat Genet 2001;29(1):100.

Szczesny B, Tann AW, Longley MJ, Copeland WC, Mitra S. Long patch base excision repair in mammalian mitochondrial genomes. J Biol Chem. 2008;283(39):26349-56. doi: https://doi.org/10.1074/jbc.M803491200

Lecrenier N, Van Der Bruggen P, Foury F. Mitochondrial DNA polymerases from yeast to man: a new family of polymerases. Gene. 1997;185(1):147-52. doi: https://doi.org/10.1016/s0378-1119(96)00663-4

Rath S, Sharma R, Gupta R, Ast T, Chan C, Durham TJ, et al. MitoCarta3.0: an updated mitochondrial proteome now with sub-organelle localization and pathway annotations. Nucleic Acids Res. 2021;49(D1):D1541-7. doi: https://doi.org/10.1093/nar/gkaa1011

Virbasius JV, Scarpulla RC. Activation of the human mitochondrial transcription factor A gene by nuclear respiratory factors: a potential regulatory link between nuclear and mitochondrial gene expression in organelle biogenesis. Proc Natl Acad Sci U S A. 1994;91(4):1309-13. doi: https://doi.org/10.1073/pnas.91.4.1309

Wang J, Wilhelmsson H, Graff C, Li H, Oldfors A, Rustin P, et al. Dilated cardiomyopathy and atrioventricular conduction blocks induced by heart-specific inactivation of mitochondrial DNA gene expression. Nat Genet. 1999;21(1):133-7. doi: https://doi.org/10.1038/5089

Sayyed UM, Mahalakshmi R. Mitochondrial protein translocation machinery: From TOM structural biogenesis to functional regulation. J Biol Chem. 2022;298(5):101870. doi: https://doi.org/10.1016/j.jbc.2022.101870

Pinz KG, Bogenhagen DF. Efficient repair of abasic sites in DNA by mitochondrial enzymes. Mol Cell Biol. 1998;18(3):1257-65. doi: https://doi.org/10.1128/MCB.18.3.1257

Greider CW, Blackburn EH. Identification of a specific telomere terminal transferase activity in Tetrahymena extracts. Cell. 1985;43(2 Pt 1):405-13. doi: https://doi.org/10.1016/0092-8674(85)90170-9

Blackburn EH, Greider CW, Szostak JW. Telomeres and telomerase: the path from maize, Tetrahymena and yeast to human cancer and aging. Nat Med. 2006;12(10):1133-8. doi: https://doi.org/10.1038/nm1006-1133

Soussi T, Wiman KG. TP53: an oncogene in disguise. Cell Death Differ. 2015;22(8):1239-49. doi: https://doi.org/10.1038/cdd.2015.53

Donehower LA, Soussi T, Korkut A, Liu Y, Schultz A, Cardenas M, et al. Integrated Analysis of TP53 Gene and Pathway Alterations in The Cancer Genome Atlas. Cell Rep. 2019;28(5):1370-1384.e5. doi: https://doi.org/10.1016/j.celrep.2019.07.001. Erratum in: Cell Rep. 2019;28(11):3010. doi: https://doi.org/10.1016/j.celrep.2019.08.061

Wanka C, Brucker DP, Bähr O, Ronellenfitsch M, Weller M, Steinbach JP, et al. Synthesis of cytochrome C oxidase 2: a p53-dependent metabolic regulator that promotes respiratory function and protects glioma and colon cancer cells from hypoxia-induced cell death. Oncogene. 2012;31(33):3764-76. doi: https://doi.org/10.1038/onc.2011.530

Bruns I, Sauer B, Burger MC, Eriksson J, Hofmann U, Braun Y, et al. Disruption of peroxisome proliferator-activated receptor γ coactivator (PGC)-1α reverts key features of the neoplastic phenotype of glioma cells. J Biol Chem. 2019;294(9):3037-50. doi: https://doi.org/10.1074/jbc.RA118.006993

Puigserver P, Wu Z, Park CW, Graves R, Wright M, Spiegelman BM. A cold-inducible coactivator of nuclear receptors linked to adaptive thermogenesis. Cell. 1998;92(6):829-39. doi: https://doi.org/10.1016/s0092-8674(00)81410-5

Andersson U, Scarpulla RC. Pgc-1-related coactivator, a novel, serum-inducible coactivator of nuclear respiratory factor 1-dependent transcription in mammalian cells. Mol Cell Biol. 2001;21(11):3738-49. doi: https://doi.org/10.1128/MCB.21.11.3738-3749.2001

Mutlu B, Puigserver P. GCN5 acetyltransferase in cellular energetic and metabolic processes. Biochim Biophys Acta Gene Regul Mech. 2021;1864(2):194626. doi: https://doi.org/10.1016/j.bbagrm.2020.194626

Brown JL, Rosa-Caldwell ME, Lee DE, Brown LA, Perry RA, Shimkus KL, et al. PGC-1α4 gene expression is suppressed by the IL-6-MEK-ERK 1/2 MAPK signalling axis and altered by resistance exercise, obesity and muscle injury. Acta Physiol (Oxf). 2017;220(2):275-88. doi: https://doi.org/10.1111/apha.12826

Steelman LS, Pohnert SC, Shelton JG, Franklin RA, Bertrand FE, McCubrey JA. JAK/STAT, Raf/MEK/ERK, PI3K/Akt and BCR-ABL in cell cycle progression and leukemogenesis. Leukemia. 2004;18(2):189-218. doi: https://doi.org/10.1038/sj.leu.2403241

Sahin E, Colla S, Liesa M, Moslehi J, Müller FL, Guo M, et al. Telomere dysfunction induces metabolic and mitochondrial compromise. Nature. 2011;470(7334):359-65. doi: https://doi.org/10.1038/nature09787. Erratum in: Nature. 2011;475(7355):254.

Kaeberlein M, McVey M, Guarente L. The SIR2/3/4 complex and SIR2 alone promote longevity in Saccharomyces cerevisiae by two different mechanisms. Genes Dev. 1999;13(19):2570-80. doi: https://doi.org/10.1101/gad.13.19.2570

Lombard DB, Alt FW, Cheng HL, Bunkenborg J, Streeper RS, Mostoslavsky R, et al. Mammalian Sir2 homolog SIRT3 regulates global mitochondrial lysine acetylation. Mol Cell Biol. 2007;27(24):8807-14. doi: https://doi.org/10.1128/MCB.01636-07

Jin L, Geng L, Ying L, Shu L, Ye K, Yang R, et al. FGF21-Sirtuin 3 Axis Confers the Protective Effects of Exercise Against Diabetic Cardiomyopathy by Governing Mitochondrial Integrity. Circulation. 2022;146(20):1537-57. doi: https://doi.org/10.1161/CIRCULATIONAHA.122.059631

Ahn BH, Kim HS, Song S, Lee IH, Liu J, Vassilopoulos A, et al. A role for the mitochondrial deacetylase Sirt3 in regulating energy homeostasis. Proc Natl Acad Sci U S A. 2008;105(38):14447-52. doi: https://doi.org/10.1073/pnas.0803790105

Hafner AV, Dai J, Gomes AP, Xiao CY, Palmeira CM, Rosenzweig A, et al. Regulation of the mPTP by SIRT3-mediated deacetylation of CypD at lysine 166 suppresses age-related cardiac hypertrophy. Aging (Albany NY). 2010;2(12):914-23. doi: https://doi.org/10.18632/aging.100252

Zhou S, Yu Q, Zhang L, Jiang Z. Cyclophilin D-mediated Mitochondrial Permeability Transition Regulates Mitochondrial Function. Curr Pharm Des. 2023;29(8):620-9. doi: https://doi.org/10.2174/1381612829666230313111314

Kuro-o M. Endocrine FGFs and Klothos: emerging concepts. Trends Endocrinol Metab. 2008;19(7):239-45. doi: https://doi.org/10.1016/j.tem.2008.06.002

Kuro-O M. The Klotho proteins in health and disease. Nat Rev Nephrol. 2019;15(1):27-44. doi: https://doi.org/10.1038/s41581-018-0078-3

Portales-Castillo I, Simic P. PTH, FGF-23, Klotho and Vitamin D as regulators of calcium and phosphorus: Genetics, epigenetics and beyond. Front Endocrinol (Lausanne). 2022;13:992666. doi: https://doi.org/10.3389/fendo.2022.992666

Zhou W, Hu G, He J, Wang T, Zuo Y, Cao Y, et al. SENP1-Sirt3 signaling promotes α-ketoglutarate production during M2 macrophage polarization. Cell Rep. 2022;39(2):110660. doi: https://doi.org/10.1016/j.celrep.2022.110660

Liu F, Wu S, Ren H, Gu J. Klotho suppresses RIG-I-mediated senescence-associated inflammation. Nat Cell Biol. 2011;13(3):254-62. doi: https://doi.org/10.1038/ncb2167. Erratum in: Nat Cell Biol. 2011;13(4):487.

Buendía P, Carracedo J, Soriano S, Madueño JA, Ortiz A, Martín-Malo A, et al. Klotho Prevents NFκB Translocation and Protects Endothelial Cell From Senescence Induced by Uremia. J Gerontol A Biol Sci Med Sci. 2015;70(10):1198-209. doi: https://doi.org/10.1093/gerona/glu170

Ikushima M, Rakugi H, Ishikawa K, Maekawa Y, Yamamoto K, Ohta J, et al. Anti-apoptotic and anti-senescence effects of Klotho on vascular endothelial cells. Biochem Biophys Res Commun. 2006;339(3):827-32. doi: https://doi.org/10.1016/j.bbrc.2005.11.094

Rausser S, Trumpff C, McGill MA, Junker A, Wang W, Ho SH, et al. Mitochondrial phenotypes in purified human immune cell subtypes and cell mixtures. Elife. 2021;10:e70899. doi: https://doi.org/10.7554/eLife.70899

Urata M, Koga-Wada Y, Kayamori Y, Kang D. Platelet contamination causes large variation as well as overestimation of mitochondrial DNA content of peripheral blood mononuclear cells. Ann Clin Biochem. 2008;45(Pt 5):513-4. doi: https://doi.org/10.1258/acb.2008.008008

Wei YH, Lee CF, Lee HC, Ma YS, Wang CW, Lu CY, et al. Increases of mitochondrial mass and mitochondrial genome in association with enhanced oxidative stress in human cells harboring 4,977 BP-deleted mitochondrial DNA. Ann N Y Acad Sci. 2001;928:97-112. doi: https://doi.org/10.1111/j.1749-6632.2001.tb05640.x

Giordano C, Iommarini L, Giordano L, Maresca A, Pisano A, Valentino ML, et al. Efficient mitochondrial biogenesis drives incomplete penetrance in Leber's hereditary optic neuropathy. Brain. 2014;137(Pt 2):335-53. doi: https://doi.org/10.1093/brain/awt343

Hurtado-Roca Y, Ledesma M, Gonzalez-Lazaro M, Moreno-Loshuertos R, Fernandez-Silva P, Enriquez JA, et al. Adjusting MtDNA Quantification in Whole Blood for Peripheral Blood Platelet and Leukocyte Counts. PLoS One. 2016;11(10):e0163770. doi: https://doi.org/10.1371/journal.pone.0163770

Izaks GJ, Westendorp RG. Ill or just old? Towards a conceptual framework of the relation between ageing and disease. BMC Geriatr. 2003;3:7. doi: https://doi.org/10.1186/1471-2318-3-7

Walker RF. Is aging a disease? A review of the Serono Symposia Workshop held under the auspices of the 3rd World Congress on the Aging Male. February 9, 2002, Berlin, Germany. Aging Male. 2002;5(3):147-69.

Gems D. Tragedy and delight: the ethics of decelerated ageing. Philos Trans R Soc Lond B Biol Sci. 2011;366(1561):108-12. doi: https://doi.org/10.1098/rstb.2010.0288

Mayhew L, Smith D. The 100-year family: Longer lives, fewer children. London: International Longevity Centre UK; 2020.

Cave D, Bubola E, Sang-Hun C. Long Slide Looms for World Population, With Sweeping Ramifications. The New York Times [Internet]. 2021 May 22. Available from: https://www.nytimes.com/2021/05/22/world/global-population-shrinking.html

Naviaux RK, Singh KK. Need for public debate about fertility treatments. Nature. 2001;413(6854):347. doi: https://doi.org/10.1038/35096737

Dunn M, Gallagher A. Ethics, ageing and the practice of care: The need for a global and cross-cultural approach. Nurs Ethics. 2021;28(3):313-5. doi: https://doi.org/10.1177/09697330211018340