From Wikipedia, the free encyclopedia

Transdifferentiation, also known as lineage reprogramming,[1] is the process in which one mature somatic cell is transformed into another mature somatic cell without undergoing an intermediate pluripotent state or progenitor cell type.[2] It is a type of metaplasia, which includes all cell fate switches, including the interconversion of stem cells. Current uses of transdifferentiation include disease modeling and drug discovery and in the future may include gene therapy and regenerative medicine.[3] The term 'transdifferentiation' was originally coined by Selman and Kafatos[4] in 1974 to describe a change in cell properties as cuticle producing cells became salt-secreting cells in silk moths undergoing metamorphosis.[5]


Davis et al. 1987 reported the first instance (sight) of transdifferentiation where a cell changed from one adult cell type to another. Forcing mouse embryonic fibroblasts to express MyoD was found to be sufficient to turn those cells into myoblasts.[6]

Natural examples[edit]

The only[citation needed] known instances where adult cells change directly from one lineage to another occurs in the species Turritopsis dohrnii (also known as the immortal jellyfish) and Turritopsis nutricula.

In newts, when the eye lens is removed, pigmented epithelial cells de-differentiate and then redifferentiate into the lens cells.[7] Vincenzo Colucci described this phenomenon in 1891 and Gustav Wolff described the same thing in 1894; the priority issue is examined in Holland (2021). [8]

In humans and mice, it has been demonstrated that alpha cells in the pancreas can spontaneously switch fate and transdifferentiate into beta cells. This has been demonstrated for both healthy and diabetic human and mouse pancreatic islets.[9] While it was previously believed that oesophageal cells were developed from the transdifferentiation of smooth muscle cells, that has been shown to be false.[10]

Induced and therapeutic examples[edit]

The first example of functional transdifferentiation has been provided by Ferber et al.[11] by inducing a shift in the developmental fate of cells in the liver and converting them into 'pancreatic beta-cell-like' cells. The cells induced a wide, functional and long-lasting transdifferentiation process that reduced the effects of hyperglycemia in diabetic mice.[12] Moreover, the trans-differentiated beta-like cells were found to be resistant to the autoimmune attack that characterizes type 1 diabetes.[13]

The second step was to undergo transdifferentiation in human specimens. By transducing liver cells with a single gene, Sapir et al. were able to induce human liver cells to transdifferentiate into human beta cells.[14]

This approach has been demonstrated in mice, rat, xenopus and human tissues.[15]

Schematic model of the hepatocyte-to-beta cell transdifferentiation process. Hepatocytes are obtained by liver biopsy from diabetic patient, cultured and expanded ex vivo, transduced with a PDX1 virus, transdifferentiated into functional insulin-producing beta cells, and transplanted back into the patient.[14]

Granulosa and theca cells in the ovaries of adult female mice can transdifferentiate to Sertoli and Leydig cells via induced knockout of the FOXL2 gene.[16] Similarly, Sertoli cells in the testes of adult male mice can transdifferentiate to granulosa cells via induced knockout of the DMRT1 gene.[17]


Lineage-instructive approach[edit]

In this approach, transcription factors from progenitor cells of the target cell type are transfected into a somatic cell to induce transdifferentiation.[2] There exists two different means of determining which transcription factors to use: by starting with a large pool and narrowing down factors one by one[18] or by starting with one or two and adding more.[19] One theory to explain the exact specifics is that ectopic Transcriptional factors direct the cell to an earlier progenitor state and then redirects it towards a new cell type. Rearrangement of the chromatin structure via DNA methylation or histone modification may play a role as well.[20] Here is a list of in vitro examples and in vivo examples. In vivo methods of transfecting specific mouse cells utilize the same kinds of vectors as in vitro experiments, except that the vector is injected into a specific organ. Zhou et al. (2008) injected Ngn3, Pdx1 and Mafa into the dorsal splenic lobe (pancreas) of mice to reprogram pancreatic exocrine cells into β-cells in order to ameliorate hyperglycaemia.[21]

Initial epigenetic activation phase approach[edit]

Somatic cells are first transfected with pluripotent reprogramming factors temporarily (Oct4, Sox2, Nanog, etc.) before being transfected with the desired inhibitory or activating factors.[22] Here is a list of examples in vitro.

Pharmacological agents[edit]

The DNA methylation inhibitor, 5-azacytidine is also known to promote phenotypic transdifferentiation of cardiac cells to skeletal myoblasts.[23]

In prostate cancer, treatment with androgen receptor targeted therapies induces neuroendocrine transdifferentiation in a subset of patients.[24][25] No standard of care exists for these patients, and those diagnosed with treatment induced neuroendocrine carcinoma are typically treated palliatively.[26]

Mechanism of action[edit]

The transcription factors serve as a short term trigger to an irreversible process. The transdifferentiation liver cells observed 8 months after one single injection of pdx1.[12]

The ectopic transcription factors turn off the host repertoire of gene expression in each of the cells. However, the alternate desired repertoire is being turned on only in a subpopulation of predisposed cells.[27] Despite the massive dedifferentiation – lineage tracing approach indeed demonstrates that transdifferentiation originates in adult cells.[28]

Mogrify algorithm[edit]

Determining the unique set of cellular factors that is needed to be manipulated for each cell conversion is a long and costly process that involved much trial and error. As a result, this first step of identifying the key set of cellular factors for cell conversion is the major obstacle researchers face in the field of cell reprogramming. An international team of researchers have developed an algorithm, called Mogrify(1), that can predict the optimal set of cellular factors required to convert one human cell type to another. When tested, Mogrify was able to accurately predict the set of cellular factors required for previously published cell conversions correctly. To further validate Mogrify's predictive ability, the team conducted two novel cell conversions in the laboratory using human cells, and these were successful in both attempts solely using the predictions of Mogrify.[29][30][31] Mogrify has been made available online for other researchers and scientists.



When examining transdifferentiated cells, it is important to look for markers of the target cell type and the absence of donor cell markers which can be accomplished using green fluorescent protein or immunodetection. It is also important to examine the cell function, epigenome, transcriptome, and proteome profiles. Cells can also be evaluated based upon their ability to integrate into the corresponding tissue in vivo[18] and functionally replace its natural counterpart. In one study, transdifferentiating tail-tip fibroblasts into hepatocyte-like cells using transcription factors Gata4, Hnf1α and Foxa3, and inactivation of p19(Arf) restored hepatocyte-like liver functions in only half of the mice using survival as a means of evaluation.[32]

Transition from mouse to human cells[edit]

Generally transdifferentiation that occurs in mouse cells does not translate in effectiveness or speediness in human cells. Pang et al. found that while transcription factors Ascl1, Brn2 and Myt1l turned mouse cells into mature neurons, the same set of factors only turned human cells into immature neurons. However, the addition of NeuroD1 was able to increase efficiency and help cells reach maturity.[33]

Order of transcription factor expression[edit]

The order of expression of transcription factors can direct the fate of the cell. Iwasaki et al. (2006) showed that in hematopoietic lineages, the expression timing of Gata-2 and (C/EBPalpha) can change whether or not a lymphoid-committed progenitors can differentiate into granulocyte/monocyte progenitor, eosinophil, basophil or bipotent basophil/mast cell progenitor lineages.[34]


It has been found for induced pluripotent stem cells that when injected into mice, the immune system of the synergeic mouse rejected the teratomas forming. Part of this may be because the immune system recognized epigenetic markers of specific sequences of the injected cells. However, when embryonic stem cells were injected, the immune response was much lower. Whether or not this will occur within transdifferentiated cells remains to be researched.[3]

Method of transfection[edit]

In order to accomplish transfection, one may use integrating viral vectors such as lentiviruses or retroviruses, non-integrating vectors such as Sendai viruses or adenoviruses, microRNAs and a variety of other methods including using proteins and plasmids;[35] one example is the non-viral delivery of transcription factor-encoding plasmids with a polymeric carrier to elicit neuronal transdifferentiation of fibroblasts.[36] When foreign molecules enter cells, one must take into account the possible drawbacks and potential to cause tumorous growth. Integrating viral vectors have the chance to cause mutations when inserted into the genome. One method of going around this is to excise the viral vector once reprogramming has occurred, an example being Cre-Lox recombination[37] Non-integrating vectors have other issues concerning efficiency of reprogramming and also the removal of the vector.[38] Other methods are relatively new fields and much remains to be discovered.

Pluripotent reprogramming[edit]

  • Almost all factors that reprogram cells into pluripotency have been discovered and can turn a wide variety of cells back into induced pluripotent stem cells (iPSCs). However, many of the reprogramming factors that can change a cell's lineage have not been discovered and these factors apply only for that specific lineage.[39]
  • The final products of transdifferentiated cells are capable of being used for clinical studies, but iPSCs must be differentiated.[39]
  • It may become possible in the future to use transdifferentiation in vivo, whereas pluripotent reprogramming may cause teratomas in vivo.[39]
  • Transdifferentiated cells will require less epigenetic marks to be reset, whereas pluripotent reprogramming requires nearly all to be removed, which may become an issue during redifferentiation.[39]
  • Transdifferentiation is geared towards moving between similar lineages, whereas pluripotent reprogramming has unlimited potential.[39]
  • Pluripotent cells are capable of self-renewal and often go through many cell passages, which increases the chance of accumulating mutations. Cell culture may also favor cells that are adapted for surviving under those conditions, as opposed to inside an organism. Transdifferentiation requires fewer cell passages and would reduce the chance of mutations.[39]
  • Transdifferentiation can also be much more efficient than pluripotency reprogramming due to the extra step involved in the latter process.[40]
  • Both pluripotent and transdifferentiated cells use adult cells, thus starting cells are very accessible, whereas human embryonic stem cells require that one navigate legal loopholes and delve into the morality of stem cell research debate.

See also[edit]


  1. ^ Orkin, S. H.; Zon, L. I. (2008). "Hematopoiesis: An Evolving Paradigm for Stem Cell Biology". Cell. 132 (4): 631–644. doi:10.1016/j.cell.2008.01.025. PMC 2628169. PMID 18295580.
  2. ^ a b Graf, T.; Enver, T. (2009). "Forcing cells to change lineages". Nature. 462 (7273): 587–594. Bibcode:2009Natur.462..587G. doi:10.1038/nature08533. PMID 19956253. S2CID 4417323.
  3. ^ a b Pournasr, B.; Khaloughi, K.; Salekdeh, G. H.; Totonchi, M.; Shahbazi, E.; Baharvand, H. (2011). "Concise Review: Alchemy of Biology: Generating Desired Cell Types from Abundant and Accessible Cells". Stem Cells. 29 (12): 1933–1941. doi:10.1002/stem.760. PMID 21997905.
  4. ^ Selman, Kelly; Kafatos, Fotis C. (1974-07-01). "Transdifferentiation in the labial gland of silk moths: is DNA required for cellular metamorphosis?". Cell Differentiation. 3 (2): 81–94. doi:10.1016/0045-6039(74)90030-X. PMID 4277742.
  5. ^ Selman, K.; Kafatos, F. C. (2013). "Transdifferentiation in the labial gland of silk moths: Is DNA required for cellular metamorphosis?". Cell Differentiation. 3 (2): 81–94. doi:10.1016/0045-6039(74)90030-x. PMID 4277742.
  6. ^ Davis, R. L.; Weintraub, H.; Lassar, A. B. (1987). "Expression of a single transfected cDNA converts fibroblasts to myoblasts". Cell. 51 (6): 987–1000. doi:10.1016/0092-8674(87)90585-x. PMID 3690668. S2CID 37741454.
  7. ^ Jopling, C.; Boue, S.; Belmonte, J. C. I. (2011). "Dedifferentiation, transdifferentiation and reprogramming: Three routes to regeneration". Nature Reviews Molecular Cell Biology. 12 (2): 79–89. doi:10.1038/nrm3043. PMID 21252997. S2CID 205494805.
  8. ^ Holland, Nicholas (2021), "Vicenzo Colucci's 1886 memoir, Intorno alla rigenerazione degli arti e della coda nei tritoni, annotated and translated into English as: Concerning regeneration of the limbs and tail in salamanders", The European Zoological Journal, 88: 837–890, doi:10.1080/24750263.2021.1943549
  9. ^ van der Meulen, T.; Mawla, A.M.; DiGruccio, M.R.; Adams, M.W.; Nies, V.; Dolleman, S.; Liu, S.; Ackermann, A.M.; Caceres, E.; Hunter, A.E.; Kaestner, K.H.; Donaldson, C.J.; Huising, M.O. (2017). "Virgin Beta Cells Persist throughout Life at a Neogenic Niche within Pancreatic Islets" (PDF). Cell Metabolism. 25 (4): 911–926. doi:10.1016/j.cmet.2017.03.017. PMC 8586897. PMID 28380380.
  10. ^ Rishniw, M.; Xin, H. B.; Deng, K. Y.; Kotlikoff, M. I. (2003). "Skeletal myogenesis in the mouse esophagus does not occur through transdifferentiation". Genesis. 36 (2): 81–82. doi:10.1002/gene.10198. PMID 12820168. S2CID 20010447.
  11. ^ Ferber S, Halkin A, Cohen H, Ber I, Einav Y, Goldberg I, Barshack I, Seijffers R, Kopolovic J, Kaiser N, Karasik A (2000) Pancreatic and duodenal homeobox gene 1 induces expression of insulin genes in liver and ameliorates streptozotocin-induced hyperglycemia.
  12. ^ a b Sarah Ferber, Amir Halkin, Hofit Cohen, Idit Ber, Yulia Einav, Iris Goldberg, Iris Barshack, Rhona Seijffers, Juri Kopolovic, Nurit Kaiser & Avraham Karasik (2000) - "Pancreatic and duodenal homeobox gene 1 induces expression of insulin genes in liver and ameliorates streptozotocin-induced hyperglycemia"
  13. ^ Shternhall-Ron K et al., Ectopic PDX-1 expression in liver ameliorates type 1 diabetes, Journal of Autoimmunity (2007), doi:10.1016/j.jaut.2007.02.010.
  14. ^ a b Tamar Sapir, Keren Shternhall, Irit Meivar-Levy, Tamar Blumenfeld, Hamutal Cohen, Ehud Skutelsky, Smadar Eventov-Friedman, Iris Barshack, Iris Goldberg, Sarah Pri-Chen, Lya Ben-Dor, Sylvie Polak-Charcon, Avraham Karasik, Ilan Shimon, Eytan Mor, and Sarah Ferber (2005) Cell-replacement therapy for diabetes: Generating functional insulin-producing tissue from adult human liver cells
  15. ^ Al-Hasani, K; Pfeifer, A; Courtney, M; Ben-Othman, N; Gjernes, E; Vieira, A; Druelle, N; Avolio, F; Ravassard, P; Leuckx, G; Lacas-Gervais, S; Ambrosetti, D; Benizri, E; Hecksher-Sorensen, J; Gounon, P; Ferrer, J; Gradwohl, G; Heimberg, H; Mansouri, A; Collombat, P (2013). "Adult Duct-Lining Cells Can Reprogram into β-like Cells Able to Counter Repeated Cycles of Toxin-Induced Diabetes". Dev. Cell. 26 (1): 86–100. doi:10.1016/j.devcel.2013.05.018. hdl:11858/00-001M-0000-0014-3C2F-6. PMID 23810513.
  16. ^ Uhlenhaut NH, Jakob S, Anlag K, Eisenberger T, Sekido R, Kress J, et al. (December 2009). "Somatic sex reprogramming of adult ovaries to testes by FOXL2 ablation". Cell. 139 (6): 1130–42. doi:10.1016/j.cell.2009.11.021. PMID 20005806.
  17. ^ Matson CK, Murphy MW, Sarver AL, Griswold MD, Bardwell VJ, Zarkower D (July 2011). "DMRT1 prevents female reprogramming in the postnatal mammalian testis". Nature. 476 (7358): 101–4. doi:10.1038/nature10239. PMC 3150961. PMID 21775990.
  18. ^ a b Ieda, M.; Fu, J. D.; Delgado-Olguin, P.; Vedantham, V.; Hayashi, Y.; Bruneau, B. G.; Srivastava, D. (2010). "Direct Reprogramming of Fibroblasts into Functional Cardiomyocytes by Defined Factors". Cell. 142 (3): 375–386. doi:10.1016/j.cell.2010.07.002. PMC 2919844. PMID 20691899.
  19. ^ Vierbuchen, T.; Ostermeier, A.; Pang, Z. P.; Kokubu, Y.; Südhof, T. C.; Wernig, M. (2010). "Direct conversion of fibroblasts to functional neurons by defined factors". Nature. 463 (7284): 1035–1041. Bibcode:2010Natur.463.1035V. doi:10.1038/nature08797. PMC 2829121. PMID 20107439.
  20. ^ Ang, Y. S.; Gaspar-Maia, A.; Lemischka, I. R.; Bernstein, E. (2011). "Stem cells and reprogramming: Breaking the epigenetic barrier?". Trends in Pharmacological Sciences. 32 (7): 394–401. doi:10.1016/ PMC 3128683. PMID 21621281.
  21. ^ Zhou, Q.; Brown, J.; Kanarek, A.; Rajagopal, J.; Melton, D. A. (2008). "In vivo reprogramming of adult pancreatic exocrine cells to β-cells". Nature. 455 (7213): 627–632. Bibcode:2008Natur.455..627Z. doi:10.1038/nature07314. PMC 9011918. PMID 18754011. S2CID 205214877.
  22. ^ Efe, J. A.; Hilcove, S.; Kim, J.; Zhou, H.; Ouyang, K.; Wang, G.; Chen, J.; Ding, S. (2011). "Conversion of mouse fibroblasts into cardiomyocytes using a direct reprogramming strategy". Nature Cell Biology. 13 (3): 215–222. doi:10.1038/ncb2164. PMID 21278734. S2CID 5310172.
  23. ^ kaur, keerat; yang, jinpu; eisenberg, carol; eisenberg, leonard (2014). "5-azacytidine promotes the transdifferentiation of cardiac cells to skeletal myocytes". Cellular Reprogramming. 16 (5): 324–330. doi:10.1089/cell.2014.0021. PMID 25090621.
  24. ^ Usmani, S; Orevi, M; Stefanelli, A; Zaniboni, A; Gofrit, ON; Bnà, C; Illuminati, S; Lojacono, G; Noventa, S; Savelli, G (June 2019). "Neuroendocrine differentiation in castration resistant prostate cancer. Nuclear medicine radiopharmaceuticals and imaging techniques: A narrative review". Critical Reviews in Oncology/Hematology. 138: 29–37. doi:10.1016/j.critrevonc.2019.03.005. PMID 31092382. S2CID 131934021.
  25. ^ Davies, AH; Beltran, H; Amina Zoubeidi (May 2018). "Cellular plasticity and the neuroendocrine phenotype in prostate cancer". Nature Reviews. Urology. 15 (5): 271–286. doi:10.1038/nrurol.2018.22. PMID 29460922. S2CID 4732323.
  26. ^ Aggarwal, R; Zhang, T; Small, EJ; Armstrong, AJ (May 2014). "Neuroendocrine prostate cancer: subtypes, biology, and clinical outcomes". Journal of the National Comprehensive Cancer Network. 12 (5): 719–26. doi:10.6004/jnccn.2014.0073. PMID 24812138.
  27. ^ Meivar-Levy, I.; Sapir, T.; Gefen-Halevi, S.; Aviv, V.; Barshack, I.; Onaca, N.; Mor, E.; Ferber, S. (2007). "Pancreatic and duodenal homeobox gene 1 induces hepatic dedifferentiation by suppressing the expression of CCAAT/enhancer-binding protein β". Hepatology. 46 (3): 898–905. doi:10.1002/hep.21766. PMID 17705277.
  28. ^ Mauda-Havakuk, M.; Litichever, N.; Chernichovski, E.; Nakar, O.; Winkler, E.; Mazkereth, R.; Orenstein, A.; Bar-Meir, E.; Ravassard, P.; Meivar-Levy, I.; Ferber, S. (2011). Linden, Rafael (ed.). "Ectopic PDX-1 Expression Directly Reprograms Human Keratinocytes along Pancreatic Insulin-Producing Cells Fate". PLOS ONE. 6 (10): e26298. Bibcode:2011PLoSO...626298M. doi:10.1371/journal.pone.0026298. PMC 3196540. PMID 22028850.
  29. ^ Mapping out cell conversion
  30. ^ Owen, Rackham; Gough, Julian (2016). "A predictive computational framework for direct reprogramming between human cell types". Nature Genetics. 48 (3): 331–335. doi:10.1038/ng.3487. hdl:1983/e6490a78-f3e8-4253-acc4-7ee181c79168. PMID 26780608. S2CID 217524918.
  31. ^ Jane Byrne (Jul 2021). Mogrify looks to transform cell therapy development. BIOPHARMA-REPORTER.COM
  32. ^ Huang, P.; He, Z.; Ji, S.; Sun, H.; Xiang, D.; Liu, C.; Hu, Y.; Wang, X.; Hui, L. (2011). "Induction of functional hepatocyte-like cells from mouse fibroblasts by defined factors". Nature. 475 (7356): 386–389. doi:10.1038/nature10116. PMID 21562492. S2CID 1115749.
  33. ^ Pang, Z. P.; Yang, N.; Vierbuchen, T.; Ostermeier, A.; Fuentes, D. R.; Yang, T. Q.; Citri, A.; Sebastiano, V.; Marro, S.; Südhof, T. C.; Wernig, M. (2011). "Induction of human neuronal cells by defined transcription factors". Nature. 476 (7359): 220–223. Bibcode:2011Natur.476..220P. doi:10.1038/nature10202. PMC 3159048. PMID 21617644.
  34. ^ Iwasaki, H.; Mizuno, S. -I.; Arinobu, Y.; Ozawa, H.; Mori, Y.; Shigematsu, H.; Takatsu, K.; Tenen, D. G.; Akashi, K. (2006). "The order of expression of transcription factors directs hierarchical specification of hematopoietic lineages". Genes & Development. 20 (21): 3010–3021. doi:10.1101/gad.1493506. PMC 1620021. PMID 17079688.
  35. ^ Patel, M.; Yang, S. (2010). "Advances in Reprogramming Somatic Cells to Induced Pluripotent Stem Cells". Stem Cell Reviews and Reports. 6 (3): 367–380. doi:10.1007/s12015-010-9123-8. PMC 2924949. PMID 20336395.
  36. ^ Adler, A. F.; Grigsby, C. L.; Kulangara, K.; Wang, H.; Yasuda, R.; Leong, K. W. (2012). "Nonviral Direct Conversion of Primary Mouse Embryonic Fibroblasts to Neuronal Cells". Molecular Therapy: Nucleic Acids. 1 (7): e32–. doi:10.1038/mtna.2012.25. PMC 3411320. PMID 23344148.
  37. ^ Sommer, C. A.; Sommer, A.; Longmire, T. A.; Christodoulou, C.; Thomas, D. D.; Gostissa, M.; Alt, F. W.; Murphy, G. J.; Kotton, D. N.; Mostoslavsky, G. (2009). "Excision of Reprogramming Transgenes Improves the Differentiation Potential of iPS Cells Generated with a Single Excisable Vector". Stem Cells. 28 (1): 64–74. doi:10.1002/stem.255. PMC 4848036. PMID 19904830.
  38. ^ Zhou, W.; Freed, C. R. (2009). "Adenoviral Gene Delivery Can Reprogram Human Fibroblasts to Induced Pluripotent Stem Cells". Stem Cells. 27 (11): 2667–2674. doi:10.1002/stem.201. PMID 19697349.
  39. ^ a b c d e f Zhou, Q.; Melton, D. A. (2008). "Extreme Makeover: Converting One Cell into Another". Cell Stem Cell. 3 (4): 382–388. doi:10.1016/j.stem.2008.09.015. PMID 18940730.
  40. ^ Passier, R.; Mummery, C. (2010). "Getting to the Heart of the Matter: Direct Reprogramming to Cardiomyocytes". Cell Stem Cell. 7 (2): 139–141. doi:10.1016/j.stem.2010.07.004. PMID 20682439.