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Induced pluripotent stem cells (iPSC) can be made from adult somatic cells by reprogramming them with Oct4, Sox2, Klf4 and c-Myc. IPSC have given rise to a new technology to study and treat human disease (Takahashi et al., 2007). However, before iPSC clinical application, we need to step back and address two main challenges: (i) Genetic stability of iPSC. (ii) Immune response of iPSC-derived cells. To address these key issues, the overall mission of this PhD thesis is to advance iPSC technology by addressing two objectives. First, is to replace c-Myc with Cyclin D1 in the reprogramming cocktail (Oct4, Sox2, Klf4 and c-Myc or Cyclin D1) and second, to study the immune response of iPSC-derived cells. The quality of the starting iPSC determines the quality of the differentiated cells to be transplanted for clinical applications. In terms of genetic stability, aberrant cell reprogramming leads to genetic and epigenetic modifications that are the most significant barriers to clinical applications of patient iPSC derivatives (Gore et al., 2011). Such aberrations can result from the cellular stress that accompanies reprogramming or from the reprogramming factors themselves (Lee et al., 2012a). IPSC made with c-Myc are neoplastic in mouse models and have a higher tumorigenic potential than embryonic stem cells, prompting a search for new pluripotency factors that can replace the oncogenic factors Klf4 and c-Myc (Huangfu et al., 2008; Miura et al., 2009; Okita et al., 2007). We chose Cyclin D1 to replace c-Myc because of previous observation it can be used to reprogram cells to iPSC (Edel et al., 2010) and because of its DNA repair function (Chalermrujinanant et al., 2016). In this thesis we adopt a synthetic mRNA method to demonstrate that Cyclin D1 and c-Myc made iPSC have equal pluripotency using standard methods of characterisation. Moreover, no significant changes in copy number variation were found between starting skin cells and iPSC highlighting it is the method of choice for generating high quality iPSC. Further in- depth analysis revealed that Cyclin D1 made iPSC have reduced genetic instability assessed by: (i) reduced DNA double strand breaks (DSB), (ii) higher nuclear amount of the homologous recombination key protein Rad51, (iii) reduced multitelomeric signals (MTS) and (iv) reduced teratoma growth kinetics in vivo, compared to c-Myc made iPSC. Moreover, we demonstrate that Cyclin D1 iPSC derived neural stem cells engraft successfully, survive long term and differentiate into mature neuron cell types with high efficiency, with no evidence of pathology in a spinal cord injury rat model. As we move towards the clinic with iPSC-derived cells for cell transplantation, the immunogenic response is thought to be one of the main advantages of iPSC technology for clinical application, because of its perceived lack of immune rejection of autologous cell therapy. We hypothesize that iPSC derived cells are unlikely to provoke an immune response. Here we have performed an analysis of the innate and adaptive immune response of human skin cells (termed F1) reprogramed to iPSC and then compared to iPSC-derived cells (termed F2) using proteomic and methylome arrays. We found little differences between MHCI expression and function; however, we discovered a short isoform of the Toll-like receptor 3 (TLR3), essential for viral dsRNA innate immune recognition, which is predominantly upregulated in all iPSC derived cells analysed and not seen in normal endogenous cells. High levels of the TLR3 isoform is associated with unresponsiveness to viral stimulation measured by lack of IL6 secretion in iPSC derived neural stem cells. We propose a new model that TLR3 short isoform competes with the full length wild type isoform destabilizing the essentially required TLR3 dimerization process. These differences could result in supressed inflammatory effects for transplanted human iPSC-derived cells in response to viral or bacterial insult. Further work to determine the in vivo effects is warranted and calls for screening of iPSC lines for TLR3 isoform expression levels before clinical use. In conclusion, this thesis has advanced iPSC technology by defining a new method that is a significant advance with novel insights that has immediate impact on current methods to generate iPSC for clinical application and more accurate disease modelling.

Pertenece a

TDX/TDR Tesis Doctorales en Red  


Requena Osete, Jordi - 

Id.: 71055959

Idioma: eng  - 

Versión: 1.0

Estado: Final

Tipo:  application/pdf -  227 p. - 

Palabras claveCèl·lules mare - 

Tipo de recurso: info:eu-repo/semantics/doctoralThesis  -  info:eu-repo/semantics/publishedVersion  - 

Tipo de Interactividad: Expositivo

Nivel de Interactividad: muy bajo

Audiencia: Estudiante  -  Profesor  -  Autor  - 

Estructura: Atomic

Coste: no

Copyright: sí

: L'accés als continguts d'aquesta tesi queda condicionat a l'acceptació de les condicions d'ús establertes per la següent llicència Creative Commons: http://creativecommons.org/licenses/by-nc/4.0/

Formatos:  application/pdf -  227 p. - 

Requerimientos técnicos:  Browser: Any - 

Relación: [IsBasedOn] TDX (Tesis Doctorals en Xarxa)

Fecha de contribución: 08-mar-2018



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