DSpace Collection:
https://hdl.handle.net/10171/5051
2024-03-28T19:54:40ZEstudio de la asociación entre la duración de la lactancia materna y la calidad de la dieta en la edad preescolar
https://hdl.handle.net/10171/69220
Title: Estudio de la asociación entre la duración de la lactancia materna y la calidad de la dieta en la edad preescolar
Abstract: --2024-03-07T00:00:00ZAdvances in precision and safety of CRISPR-based gene targeting for Primary Hyperoxaluria Type 1
https://hdl.handle.net/10171/69165
Title: Advances in precision and safety of CRISPR-based gene targeting for Primary Hyperoxaluria Type 12024-02-22T00:00:00ZChanges in adipose tissue plasticity after bariatric surgery and their role in the improvement of obesity-associated comorbidities
https://hdl.handle.net/10171/69153
Title: Changes in adipose tissue plasticity after bariatric surgery and their role in the improvement of obesity-associated comorbidities
Abstract: Adipose tissue (AT) is considered a plastic and dynamic endocrine organ with
obesity driving changes in its biomechanical properties as well as in its extracellular matrix
(ECM) remodelling, inflammation and mechanotransduction profiles, leading to the
impairment of whole-body homeostasis. To achieve important and sustained weight loss
as well as for the resolution of obesity-associated diseases, bariatric surgery (BS) is
considered the most effective option in adequately selected patients. Despite great efforts
to understand the processes involved in both, the development of dysfunctional AT and the
favourable outcomes of BS, the underlying biological mechanisms have not been fully
disentangled. Therefore, the objective of the present PhD thesis is to evaluate changes in
AT plasticity together with their associations with the inflammation profile as well as ECM
remodelling and mechanotransduction properties in an animal model of diet-induced
obesity (DIO) and in patients with obesity. At the same time, we aimed to analyse the effect
of BS on these biological processes, beyond the mere weight loss. We found that changes
in the biomechanical properties of AT in obesity, including decreased Young’ modulus
(E), ultimate tensile strength (UTS) and strain at UTS, were associated with the
deterioration of body homeostasis. In this line, obesity induced changes in the
inflammation, fibrosis and ECM remodelling profiles not only in AT but also in the liver
being also related to the development of obesity comorbidities. Our findings also provide
new insights into AT adaptation after BS beyond caloric restriction, being demonstrated by
significant changes in the mechanotransduction and inflammatory profiles together with
the decrease in the crosslinking and synthesis of collagens as well as an increase in its
degradation. Our data also supports the notion that the higher blood vessel density found
in AT after BS is involved in the increased E, UTS and strain at UTS values, providing at
the same time higher stiffness and increased strain capacity. Furthermore, the inhibition of
NLRP3, a key component of the inflammasome involved in the regulation of inflammation,
in visceral adipocytes significantly blocked inflammation and fibrosis suggesting its
potential to regulate the development of obesity-associated comorbidities. In terms of
fibrosis-inducing factors, we also showed a novel role of dermatopontin in the pathological
AT ECM remodelling during obesity. Finally, we proposed that the measurement of the
Adiponectin/Leptin ratio after BS might constitute a significant factor for evaluating the
remission of type 2 diabetes after bariatric procedures.; El tejido adiposo (TA) es un órgano endocrino plástico y dinámico, que
experimenta cambios en sus propiedades biomecánicas, así como en los perfiles de
remodelación de su matriz extracelular (MEC), inflamación y mecanotransducción con la
obesidad. La cirugía bariátrica (CB) constituye la opción más efectiva para lograr una
pérdida de peso importante y sostenida en el tiempo, así como para la resolución de
comorbilidades asociadas a la obesidad en pacientes adecuadamente seleccionados. A
pesar de los grandes esfuerzos realizados para comprender los procesos involucrados tanto
en el desarrollo del TA disfuncional como en los efectos favorables de la CB, no se han
desentrañado completamente los mecanismos biológicos subyacentes. Por todo ello, el
objetivo de la presente tesis doctoral es evaluar los cambios en la plasticidad del TA,
además de estudiar su relación con el perfil inflamatorio, así como con el remodelado de
la MEC y propiedades de mecanotransducción en un modelo animal de obesidad inducida
por dieta (OID) y en pacientes con obesidad. Al mismo tiempo nos propusimos analizar el
efecto de la CB sobre dichos procesos biológicos, más allá de la mera pérdida de peso.
Nuestros resultados muestran que los cambios en las propiedades biomecánicas del TA en
animales con obesidad, incluyendo la disminución del módulo de Young (E), la resistencia
máxima a la tracción (RMT) y la tensión en RMT, se asociaron con el deterioro de la
homeostasis corporal. En esta línea, la obesidad indujo cambios en los perfiles de
inflamación, fibrosis y remodelado de la MEC no exclusivamente en el TA, sino también
en el hígado, relacionándose también con el desarrollo de comorbilidades asociadas a la
obesidad. Los datos obtenidos revelan nuevos hallazgos sobre la adaptación del TA tras
CB más allá de la restricción calórica, demostrando cambios significativos en los perfiles
inflamatorios y de mecanotransducción junto con la disminución en la conformación
reticulada de colágenos y su síntesis, así como un aumento en su degradación. Nuestros
resultados también respaldan la noción de que la mayor densidad de vasos sanguíneos
encontrada en el TA tras CB está asociada con un aumento de E, RMT y tensión en RMT,
proporcionando al mismo tiempo una mayor rigidez y capacidad de tensión. Además, la
inhibición de NLRP3, un componente clave del inflamasoma involucrado en la regulación
de la inflamación, en los adipocitos viscerales bloqueó significativamente la inflamación y
la fibrosis, sugiriendo ser un potencial regulador del desarrollo de comorbilidades
asociadas a la obesidad. En términos de factores inductores de la fibrosis, también
mostramos el papel novedoso de la dermatopontina en la remodelación patológica de la
MEC del TA en pacientes con obesidad. Finalmente, descubrimos que el cociente
22
Adiponectina/Leptina podría constituir un factor a tener en cuenta a la hora de evaluar la
remisión de la diabetes tipo 2 tras la CB en pacientes con obesidad.2024-02-22T00:00:00ZModelling, design, fabrication and characterization of engineered human myocardium made with melt electrowriting and cardiac cells derived from hiPSCs
https://hdl.handle.net/10171/69152
Title: Modelling, design, fabrication and characterization of engineered human myocardium made with melt electrowriting and cardiac cells derived from hiPSCs
Abstract: The adult human heart has evolved to become a highly specialized organ, whose continuous pumping
of blood is critical for survival. However, its ability to regenerate or self-repair following injury is very
limited, so consequently any event or disease resulting in damage to the heart poses a serious threat
to the patient. Moreover, cardiovascular diseases represent one of the most pressing healthcare
concerns nowadays, as they are the leading cause of death worldwide, and the number of cases is
only expected to increase in the following years. Despite great progress made over the years to treat
cardiovascular diseases, to date there is no therapy able to fully cure a heart that has been damaged.
In consequence, there is a dire need to generate new strategies to repair the heart damage and
restore the lost cardiac function, as well as to develop accurate modelling platforms to advance in
the understanding of disease progression and assess the effectiveness of new drugs.
Since its advent, cardiac tissue engineering and regenerative medicine has been regarded as a
promising candidate to realise this enormous challenge. Given its interdisciplinary nature, scientific
breakthroughs in different areas such as cellular reprogramming, polymer chemistry, and additive
manufacturing technologies have resulted in the advancement of cardiac tissue engineering and
regenerative medicine over the years. One of such cornerstone discoveries was the generation of
induced pluripotent stem cells and subsequent differentiation to different cardiac phenotypes, and
the present Thesis revolves around their application to generate patient-specific cardiac disease
models and humanised engineered functional cardiac minitissues.
Firstly, we reprogrammed peripheral blood mononuclear cells from a transthyretin amyloid
cardiomyopathy patient, resulting in the generation of a new cell line carrying a c.128G>A
(p.Ser43Asn) mutation in the transthyretin gene. Experiments demonstrated the efficacy and safety
of the approach, confirming the pluripotency of the cells, the presence of the disease-causing
mutation, and the removal of reprogramming vectors. This cell line, which is now available in a
repository, can be used to investigate disease biology, molecular mechanisms and progression; as
well as an advanced cellular model to test novel therapeutic strategies.
Secondly, we aimed to generate functional human minitissues by combining human cardiomyocytes
derived from induced pluripotent stem cells and tridimensional fibrillar scaffolds generated with the
technology of melt electrowriting. Compared to conventional two-dimensional cell culture, the
cardiac minitissues demonstrated enhanced maturation, with a significant increase in conduction
velocity, presence of connexin 43 and expression of cardiac-associated genes such as MYL2, GJA5
and SCN5A, and isoform ratios MYH7/MYH6 and MYL2/MYL7 after 28 days in culture. When
investigating the effect of the scaffold fibres on the cells, we found that cardiomyocytes placed close
to the fibre were arranged parallel to it, but that alignment was progressively lost towards the centre
of the scaffold pore. We then used these data to develop simulations capable of accurately
reproducing the experimental performance. In-depth gauging of the structural disposition and
intercellular connectivity allowed us to develop an improved computational model able to predict
the relationship between cardiac cell alignment and functional performance. This study lays down
the path for advancing in the development of in silico tools to predict cardiac biofabricated tissue
evolution after generation, and maps the route towards more accurate and biomimetic tissue
manufacture.
We next aimed at increasing the biological representativity of the cardiac minitissues, by
implementing a few changes in cellular (addition of induced pluripotent stem cell-derived cardiac
fibroblasts) and hydrogel (substitution of Matrigel for fibrin) composition. We also sought to control
cardiomyocyte behaviour based on melt electrowritten scaffold geometry. For this, we hypothesized
that diamond-based scaffolds would induce cardiomyocyte contraction in the direction of least
mechanical resistance, i.e., the small diagonal of the diamonds. The characterization of the new
cardiac minitissues demonstrated functional maturation consistent with the previous work in terms
of gene expression and conduction velocity, although the observed low initial cell retention within
the scaffold highlighted the need of new strategies to improve cell seeding efficiency. When
comparing contractile dynamics between melt electrowritten scaffolds made with square,
rectangular, and diamond-shaped pores, we found that the latter resulted in significantly faster,
stronger and aligned contraction in the direction that we had anticipated. The potential use of the
cardiac minitissues as therapy agents was tested by implanting the constructs in a murine model of
chronic myocardial infarction. Compared to controls, implanted animals showed significant
improvement, including higher left ventricular ejection fraction and greater wall thickness.
Finally, in another attempt to enhance the biological representativity of the constructs, a proof of
concept was made to generate melt electrowritten ellipsoidal scaffolds with controlled pore
architecture. In summary, the present Thesis revolves around human induced pluripotent stem cells
and melt electrowriting as cornerstone tools for cardiac tissue engineering and regenerative
medicine efforts. By combining both and iteratively optimising the design and experimental
conditions, we were able to generate human functional cardiac minitissues of increased biological
relevance.2024-02-22T00:00:00Z