Myocardial infarction is one of the leading causes of mortality worldwide. Following the pathological event, the cells of the cardiac tissue, the cardiomyocytes, undergo a progressive lack of oxygen and are replaced by fibrous tissue. This tissue has functional and structural characteristics different from healthy cardiac tissue, negatively influencing heart function. Currently available therapies, which are pharmacological or surgical, offer limited functional recovery. To overcome the limitations of traditional medicine, scientific research is seeking to deepen techniques in the emerging field of “regenerative medicine”. In particular, tissue engineering is moving towards the creation of a cardiac patch based on biomaterials and cells capable of regenerating myocardial tissue following a heart attack. This study aims to develop an implantable patch at the myocardium level, characterized by decellularized extracellular matrix of the myocardial tissue of a pig’s heart and developed through 3D bioprinting technology. For this purpose, a bioink based on natural polymers and enriched by decellularized extracellular matrix (dECM), obtained from the pig’s heart, was developed to recreate the extracellular environment. The main challenge is to obtain a structure capable of reproducing the mechanical, biological and functional properties of myocardial tissue, optimizing a bioink suitable for 3D bioprinting based on photopolymerization. For this purpose, various functionalized materials, such as methacrylated gelatin or GelMA, methacrylated alginate or AlMA and methacrylated hyaluronic acid or HAMA, have been explored, with the aim of obtaining a printed construct with the desired characteristics. Furthermore, the purpose of this study is also to evaluate the role that dECM plays in promoting cell proliferation. Preliminarly, to achieve the final goal, an in-depth literature review regarding the composition and structure of cardiac tissue and the state of advancement of scientific research to date in this field was performed. After the synthesis of methacrylated polymers, rheological tests were performed on polymer bioinks to select those with optimized mechanical properties. Furthermore, with the aim of obtaining a patch suitable for cardiac application, decellularization tests and in vitro biological tests were performed to evaluate the correct elimination of cellular material. The results obtained in this study are encouraging as they underline how the presence of dECM in the polymeric patch stimulates cell growth and orientation. However, process of synthesizing the bioink and integrating the dECM needs to be improved and optimized, in order to obtain the optimal composition for the 3D-bioprinting process. Further studies are expected to deepen and continue what has been discussed in this thesis, with the aim of creating a cardiac patch aimed at the replication and regeneration of myocardial tissue.
L'infarto miocardico è una delle principali cause di mortalità a livello mondiale. In seguito all'evento patologico, le cellule del tessuto cardiaco, i cardiomiociti, vanno incontro a una progressiva mancanza di ossigeno e vengono sostituite da tessuto fibroso. Questo tessuto ha caratteristiche funzionali e strutturali diverse dal tessuto cardiaco sano, influenzando negativamente la funzione cardiaca. Le terapie attualmente disponibili, farmacologiche o chirurgiche, offrono un recupero funzionale limitato. Per superare i limiti della medicina tradizionale, la ricerca scientifica sta cercando di approfondire le tecniche nel campo emergente della “medicina rigenerativa”. In particolare, l'ingegneria tissutale si sta muovendo verso la creazione di un patch cardiaco basato su biomateriali e cellule in grado di rigenerare il tessuto miocardico dopo un attacco cardiaco. Questo studio si propone di sviluppare un patch impiantabile a livello del miocardio, caratterizzato da matrice extracellulare decellularizzata del tessuto miocardico di un cuore di maiale e sviluppato attraverso la tecnologia di bioprinting 3D. A questo scopo, un bioinchiostro a base di polimeri naturali e arricchito di matrice extracellulare decellularizzata (dECM), ottenuta dal cuore di maiale, è stato sviluppato per ricreare l'ambiente extracellulare. La sfida principale è quella di ottenere una struttura in grado di riprodurre le proprietà meccaniche, biologiche e funzionali del tessuto miocardico, ottimizzando un bioinchiostro adatto al 3D bioprinting basato sulla fotopolimerizzazione. A tal fine, diversi materiali funzionalizzati, quali gelatina metacrilata o GelMA, alginato metacrilato o AlMA e acido ialuronico metacrilato o HAMA, sono stati esplorati con l'obiettivo di ottenere un costrutto stampato con le caratteristiche desiderate. Inoltre, lo scopo di questo studio è anche quello di valutare il ruolo del dECM nel promuovere la proliferazione cellulare. In via preliminare, per raggiungere l'obiettivo finale, è stata effettuata un'approfondita revisione della letteratura riguardante la composizione e la struttura del tessuto cardiaco e lo stato di avanzamento della ricerca scientifica in questo campo. Dopo la sintesi dei polimeri metacrilati, sono stati effettuati test reologici sui bioink polimerici per selezionare quelli con proprietà meccaniche ottimizzate. Inoltre, con l'obiettivo di ottenere un patch adatto all'applicazione cardiaca, sono stati eseguiti test di decellularizzazione e test biologici in vitro per valutare la corretta eliminazione del materiale cellulare. I risultati ottenuti in questo studio sono incoraggianti, in quanto sottolineano come la presenza di dECM nel patch polimerico stimoli la crescita e l'orientamento delle cellule. Tuttavia, il processo di sintesi del bioink e di integrazione della dECM deve essere migliorato e ottimizzato, per ottenere la composizione ottimale per il processo di 3D bioprinting. Con ulteriori studi si prevede di approfondire e proseguire quanto discusso in questa tesi, con l'obiettivo di di creare un patch cardiaco finalizzato alla replica e alla rigenerazione del tessuto miocardico.
3D Bioprinting of a cardiac patch based on decellularised extracellular matrix for myocardial regeneration
De Caro, Margherita
2023/2024
Abstract
Myocardial infarction is one of the leading causes of mortality worldwide. Following the pathological event, the cells of the cardiac tissue, the cardiomyocytes, undergo a progressive lack of oxygen and are replaced by fibrous tissue. This tissue has functional and structural characteristics different from healthy cardiac tissue, negatively influencing heart function. Currently available therapies, which are pharmacological or surgical, offer limited functional recovery. To overcome the limitations of traditional medicine, scientific research is seeking to deepen techniques in the emerging field of “regenerative medicine”. In particular, tissue engineering is moving towards the creation of a cardiac patch based on biomaterials and cells capable of regenerating myocardial tissue following a heart attack. This study aims to develop an implantable patch at the myocardium level, characterized by decellularized extracellular matrix of the myocardial tissue of a pig’s heart and developed through 3D bioprinting technology. For this purpose, a bioink based on natural polymers and enriched by decellularized extracellular matrix (dECM), obtained from the pig’s heart, was developed to recreate the extracellular environment. The main challenge is to obtain a structure capable of reproducing the mechanical, biological and functional properties of myocardial tissue, optimizing a bioink suitable for 3D bioprinting based on photopolymerization. For this purpose, various functionalized materials, such as methacrylated gelatin or GelMA, methacrylated alginate or AlMA and methacrylated hyaluronic acid or HAMA, have been explored, with the aim of obtaining a printed construct with the desired characteristics. Furthermore, the purpose of this study is also to evaluate the role that dECM plays in promoting cell proliferation. Preliminarly, to achieve the final goal, an in-depth literature review regarding the composition and structure of cardiac tissue and the state of advancement of scientific research to date in this field was performed. After the synthesis of methacrylated polymers, rheological tests were performed on polymer bioinks to select those with optimized mechanical properties. Furthermore, with the aim of obtaining a patch suitable for cardiac application, decellularization tests and in vitro biological tests were performed to evaluate the correct elimination of cellular material. The results obtained in this study are encouraging as they underline how the presence of dECM in the polymeric patch stimulates cell growth and orientation. However, process of synthesizing the bioink and integrating the dECM needs to be improved and optimized, in order to obtain the optimal composition for the 3D-bioprinting process. Further studies are expected to deepen and continue what has been discussed in this thesis, with the aim of creating a cardiac patch aimed at the replication and regeneration of myocardial tissue.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/227440