Carboxymethyl cellulose-based cryogels as a scaffoold for pancreatic ans skeletal muscle tissue engineering
- Autores: Ferran Velasco Mallorqui
- Directores de la Tesis: Javier Ramón-Azcón (dir. tes.), Ramón Farré Ventura (tut. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2021
- Idioma: inglés
- Tribunal Calificador de la Tesis: Anna Novials Sardà (presid.), Óscar Castaño Linares (secret.), Cécile Legallais (voc.)
- Materias:
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- Resumen
Diabetes incidence highly increased in the last years. According to IDF (International Diabetes Federation), 463 million people suffered this disease in 2019. The estimations of diabetic people highly increase in the upcoming years, rising approximately to 700 million diabetic patients in 2045 [1]. Type 2 diabetes (T2D) is the most common type of diabetes, representing 90% of diabetic patients. It occurs when the body becomes resistant to insulin.
Body insulin resistance confirms that T2D is not only a pancreatic disease, as there are many other tissues involved, like liver, adipose tissue, or skeletal muscle. This last has a significant implication in glucose-insulin homeostasis as it is one of the main glucose-consuming organs in the body.
Nowadays, to study how two tissues crosstalk between them, animal testing is the gold standard. However, the unmatching physiological behaviors compared to humans, the variability between different animals, ethical dilemmas, and the need to go for more personalized medicine activates the search for other suitable alternatives. At this point, Organs-on-a-chip appeared as a valid alternative. Organs-on-a-chip (OOC) are 3D bioengineered microfluidic cell culture platforms to simulate microphysological environments of an organ or its specific functions.
Nowadays, to engineer the tissues for OOC applications, encapsulating cells inside hydrogels is the most common technique. Its beneficial properties include high water content, mechanical adjustability, and moldability to generate the desired architectures [2]. However, its small porosity limits nutrient and oxygen diffusion through it [3].
This problem is a significant limitation when pancreatic islets are encapsulated inside hydrogels due to their size (~100 μm of diameter). Pancreatic islets are cell aggregations composed of many different cells as insulin-secreting cells (Beta-cells) or glucagon-secreting cells (alpha-cells). Similarly, skeletal muscle tissue is generally encapsulated in small bundles. Skeletal muscle is a highly aligned and multinucleated tissue formed from the fusion of single cells, called myoblasts, into multinucleated cells, called myotubes.
Cryogels have been proposed as a valid alternative to overcome these limitations. Cryogels are fabricated by crosslinking a prepolymer solution at sub-zero temperatures, so while the material crosslinks, water freezes, generating the desired micropore architecture. After thawing, cryogels are sponge-like scaffolds with microporous structure, high interconnected porosity, high diffusivity, fine-tuned properties, and desired internal pore architecture.
This thesis developed two cryogel scaffolds made of gelatin and carboxymethylcellulose with different pore architectures to engineer pancreatic and skeletal muscle tissues. Here, we proved that the achieved pore architecture fits with the prerequisites to engineer each tissue. Moreover, the mechanical and physical properties of each scaffold highly resemble the 3D microenvironment of each tissue. In pancreatic tissue, we generate a random pore cryogel to aggregate beta-cells to form pseudoislets. We proved that these engineered pseudoislets are viable, functional responding correctly to the glucose and improving insulin response compared to monolayer results. In the skeletal muscle approach, we could develop a highly aligned pore architecture to prompt cell alignment and cell fusion. Moreover, we incorporate carbon nanotubes to enhance the electrical conductivity of the scaffold, so by applying electrical pulse stimulation, we could improve the early steps of the myogenic maturation.
[1] International Diabetes Federation, 9th IDF diabetes atlas. 2019.
[2] K. Yue et al., “Synthesis, properties, and biomedical applications of gelatin methacryloyl (GelMA) hydrogels,” Biomaterials, vol. 73, no. 3, pp. 254–271, 2016, doi: 10.1016/j.biomaterials.2015.08.045.Synthesis.
[3] M. K. Lee, M. H. Rich, K. Baek, J. Lee, and H. Kong, “Bioinspired tuning of hydrogel permeability-rigidity dependency for 3D cell culture,” Sci. Rep., vol. 5, pp. 1–7, 2015, doi: 10.1038/srep08948.
