THE BREAKTHROUGH OF SCIENCEINDUCED-PLURIPOTENT STEM CELL

Lim Kun Ye | Nastaszia G. | Norma Y. | Nuruladha | Thara K. | Vincentsia V.

Gene & Tissue Culture Technology

BIO3113 / SCT60103

★ Cell dedifferentiation → a process whereby differentiated cells undergo reverse development to a simpler state which is similar to stem cells.

★ Reversion of a cell is associated with a re-entry into cell cycle, accompanied by chromatin rearrangement and a possible disassembly of nucleoli and DNA condensation, reducing protein synthesis.

★ It can occur i) NATURALLY, e.g: in damaged tissue (most commonly studied in amphibians which capable of organ regeneration) ii) INDUCED BY NUCLEAR REPROGRAMMING IN VITRO by introducing genes encoding critical transcription proteins, which regulates other genes important for early steps of embryonic development

★ As cancer can only be established from cells capable to proliferate, and not terminally differentiated cells, cellular dedifferentiation has also been implicated in cancer. (Sell 1993)

Cell Dedifferentiation

Figure 1. Illustration of different routes of cells regeneration(A) stem cells: self-renewing and giving rise to one or more differentiated cells(B) dedifferentiation: cells revert to a precursor cell that can divide to produce more differentiated cells(C) transdifferentiation: cells change from one cell type to another

(Scientific Malaysian 2013)

Dedifferentiation at 4 different levels

1. Genetic level Gene related to development activity is repressed, while genes that keep the cell in the undifferentiated state are activated.

2. Protein level -> up-regulation of proteins that related to the progenitor cells-> down-regulation of proteins that related to differentiated cell

3. MorphologyDedifferentiated cells are smaller, have fewer organelles & higher karyoplasmic ratio

4. FunctionThe cell regains the capacity to proliferate.

07)

(Cai, Fu & Sheng 2007)

What is Induced-Pluripotent Stem Cells (iPSCs) ?

➢ Adult cells that have been genetically reprogrammed to an embryonic stem cell–like state

➢ These cells are forced to express genes and factors to maintain the properties of pluripotent embryonic stem cells --> enables the development of an unlimited source of many type of human cell for therapeutic purposes

➢ Potential utility of iPSCs : tool for drug development, regenerative medicine, disease modelling

(+) Poses no risk of immune rejection/ genetic incompatibility(+)Compared to stem cells obtained from embryo,dedifferentiation will less likely to provoke ethical disputes

(Takahashi et al. 2007)

Figure 2. Diagram showing generation of human iPCs for use in cell therapy, in vitro human pathology modelling and in drug discovery.

The first discovery of iPCS::➢ Mouse: induced embryonic fibroblast (Takahashi & Yamanaka

2006)➢ Human: induced embryonic fibroblast iPSCs (Takahashi et al.

2007)

(Yang et.al 2015)

● The genetic information of adult stem cells ‘s are conserved in iPSCs and maintained.

● Thus, iPSC-derived cells are often used as disease models by comparing with their ex vivo counterparts

● Mainly used in monogenic disease modelling, such as:1) Neurological disorders (Parkinson’s disease and Reet

syndrome)2) Blood diseases (Fanconi anaemia)3) Cardiac syndromes (LEOPARD) 4) Pancreatic type 1 diabetes5) Hepatic disorders (alpha-1 antitrypsin deficiency)

(Wu & Hochedlinger 2011)

Medical Application of iPSCs: Disease Modelling

Medical Application of iPSCs: Cell-based therapy

Cells Medical ApplicationsiPSC-derived Schwann cells

-Facilitate axonal growth in the injured area -Promote nerve repair by ensheathing and remyelinating the regenerated axons

iPSC-derived hepatocytes

-used in Liver cell therapies- engineered donor graft derived from iPSCs (including re-cellularized biomatrix and liver buds produced from iPSCs ) provide organs for liver transplantation and treat organ failure

(Yu et al. 2014)

Table 1. Table showing the application of IPSCs in cell-based therapy

Medical Application of iPSCs : Patient-Specific Drug

(Yu, Wang & Nyberg 2014)Figure 2. Diagram showing generation of human iPCs to develop patient-specific drug

• Low efficiency of reprogramming in vitro --> additional rare events are necessary to generate iPSCs

• There is variety of iPSC lines with respect to differentiation tendency and tumorigenic risk

• Require safe and highly efficient generation of stem cells• Require methods to reprogram cells while minimizing

DNA alterations• Need to evaluate whether subtle differences between

iPSC and ESC might affect their research applications and therapeutic potential

Challenges of iPSCs Research

12 September 2014: World 1st stem cell trial by Dr. Masayo Takahashi

• assessing safety and the therapeutic potential of transplanted human retinal pigmented epithelial cells (RPE cells)

• made from the iPS cells reprogrammed from patient’s skin cell.

• Result: after 6 months: appears to be safe → 1 year safety report appearing soon

• The patient experience no recurrence of neovascularization even without any anti-VEGF injections.

• Challenges: mutations were detected in iPS cell-derived RPE cells prepared for second patients → safetiness is not guaranteed

Current Development of IPSCs Research

(Takahashi et al. 2014)

Thanks!

Any questions?

Cai, S, Fu, X & Sheng, Z 2007, 'Dedifferentiation: A New Approach in Stem Cell Research', BioScience, vol. 57, no. 8, pp. 655-662, viewed 11 September 2015, <http://bioscience.oxfordjournals.org/content/57/8/655.full.pdf+html>.http://intranet.tdmu.edu.ua/data/kafedra/internal/in_mow/classes_stud/uk.../med/

Charles, A, Goldthwaite 2006, 'The Promise of Induced Pluripotent Stem Cells (iPSCs)', U.S Department of Health and Human Discovery, National Institute of Health, viewed on 20 September 2015,<http://stemcells.nih.gov/info/Regenerative_Medicine/pages/2006chapter10.aspx>

James, F.B. et al,. 2006, 'Alternate Methods for Preparing Pluripotent Stem Cells' U.S Department of Health and Human Discovery, National Institute of Health, viewed on 20 September 2015,<http://stemcells.nih.gov/info/Regenerative_Medicine/pages/2006Chapter8.aspx>

Kim, C 2014, 'Disease modeling and cell based therapy with iPSC: future therapeutic option with fast and safe application', Blood Research, vol. 49, no. 1, pp. 7-14, MEDLINE, EBSCOhost, viewed 26 September 2015.

Lee, J 2013, 'Breaking The Regeneration Barrier', Scientific Malaysian Magazine, viewed on 22 September 2015, <http://magazine.scientificmalaysian.com/article/science-storytelling/breaking-regeneration-barrier/>.

References

Nakamura, M & Okano, H 2012, ‘Cell transplantation therapies for spinal cord injury focusing on induced pluripotent stem cells’, Cell Res, vol. 23, no. 1, pp.70-80, viewed 24 September 2015, <http://www.nature.com/cr/journal/v23/n1/full/cr2012171a.html>.

Sell, S 1993, 'Cellular Origin of Cancer: Dedifferentiation or Stem Cell Maturation Arrest?', Environmental Health Perspectives, p. 15.

Takahashi, K & Yamanaka, S 2006,‘Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors’,Cell, vol.126, pp.663–676.

Takahashi, K, Tanabe, K, Ohnuki, M, Narita, M, Ichisaka, T, Tomoda, K & Yamanaka, S 2007.‘Induction of pluripotent stem cells from adult human fibroblasts by defined factors,Cell, vol.131, pp.861–872.

Takahashi, M, Kamao, H, Mandai, M, Okamoto, S, Sakai, N, Suga, A, Sugita, S & Kiryu, J 2014, 'Characterization of Human Induced Pluripotent Stem Cell-Derived Retinal Pigment Epithelium Cell Sheets Aiming for Clinical Application', Stem Cell Reports, vol. 2, pp. 205-218.

Wu, S & Hochedlinger, K, 2011, ‘Harnessing the potential of induced pluripotent stem cells for regenerative medicine’, Nature Cell Biology, vol. 13, no. 5, pp. 497-505, viewed 23 September 2015, <http://www.ncbi.nlm.nih.gov/pubmed/21540845>.

Yang, C, Al-Aama, J, Stojkovic, M, Keavney, B, Trafford, A, Lako, M and Armstrong, L, 2015, ‘Concise Review: Cardiac Disease Modeling Using Induced Pluripotent Stem Cells’, STEM CELLS, vol. 33, no. 9, pp.2643-2651, viewed 23 September 2015 <http://onlinelibrary.wiley.com/doi/10.1002/stem.2070/abstract>.

Yu, Y, Wang, X & Nyberg, S 2014,‘Potential and Challenges of Induced Pluripotent Stem Cells in Liver Diseases Treatment’, Journal of Clinical Medicine, vol. 3, no. 3, pp.997-1017.