京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22302号 / 医博第4543号 / 新制||医||1040(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 川口 義弥, 教授 妹尾 浩, 教授 濵﨑 洋子 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(医学) / 甲第24526号 / 医博第4968号 / 新制||医||1065(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 齋藤 潤, 教授 柳田 素子, 教授 江藤 浩之 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(医学) / 甲第24198号 / 医博第4892号 / 新制||医||1060(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 川口 義弥, 教授 松田 秀一, 教授 小濱 和貴 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Concern over kidney disease has increased dramatically in recent years within the medical community. It is estimated that approximately one in fifteen Americans, nearly 20 million people, experience chronic kidney disease with most of those diagnosed progressing to kidney failure. The ultimate treatment available for end stage renal failure is whole kidney transplantation. However, there are very few kidneys available for patients to receive and those patients who are fortunate enough to receive an organ must remain on immunosuppressive medication for the remainder of their lives. The United States Department of Health & Human Services have reported that 18 people die every day while on the waiting list for organ donations. The treatment is fairly successful as 69% of patients who receive a kidney transplant are still alive 5 years after the transplant. Tissue engineered organs could be a promising alternative for whole organ transplantation. The overall objective is to repopulate appropriate decellularized scaffolds from pigs, which are not immunogenic, with a patient's own cells to achieve a functional organ. Therefore, there would be an inexhaustible source of organs ready for transplantation without the risk of immune rejection. The naturally obtained scaffolds devoid of immunogens are a potential matrix to create artificial kidneys. Repopulation of decellularized rat kidneys with renal progenitor cells has been reported in previous studies. This dissertation reports the scale-up of the previous technology and building of partially functional human-sized kidneys. In the first step, we investigated various cell lysing agents and developed an automated decellularization procedure for whole porcine kidney decellularization. We also developed a preservation method for native and decellularized kidneys to avoid spoilage before and after decellularization. We also developed a decontamination procedure for whole porcine kidneys. Finally, we recellularized whole porcine kidney scaffolds with renal epithelial cells and achieved partial repopulation of the renal structure.

Lower respiratory diseases are currently the third leading cause of death worldwide. For many end-stage patients with these diseases, there is no cure and a shortage of donor organs available for transplant. A promising solution is to design regenerative scaffolds or complete bioengineered lungs, using decellularized lung tissues as a template for regeneration. Recent advances in the field have made significant strides towards developing a transplantable lung. However, the current technology has not produced a functional lung for in vivo transplant due to immature gas exchange barriers. The mechanisms driving alveolar barrier maturation and role that extracellular matrix (ECM) plays within the strengthening of each type of junction are not fully understood. This research has characterized and tailored a decellularized ECM (dECM) coating for the in vitro study of dECM component depletion and potential effects on cell barrier function, attachment, and survival. Adjustments to dECM digestion duration drastically changed the resulting structural and biochemical properties for each cellular microenvironment. Shorter digestion time resulted in a dense branching of the ECM architecture and biomimetic mechanical properties needed for epithelial culture. Also, through systematic supplementation of essential basement membrane (BM) proteins to dECM, we have found that supplementation with laminin enhanced barrier strength by ZO-1 junction stabilization. This indicates that dECM can promote barrier formation but may have lost vital proteins that need to be replenished. Laminin-mediated barrier function was determined to be caused by the upregulation of the Epac/Rap1 pathway. This pathway has previously been implicated in lung endothelial barriers but not alveolar epithelial junction strengthening. Finally, to establish the translatability of these findings to whole lung recellularization, the dECM coating was used to pre-treat the airways of decellularized lungs for recellularization. Culture of MLE12 mouse epithelial cells into dECM-coated lungs increased cell survival and distribution. In combination with dECM coatings, rotational cell seeding improved cell dispersal and viability. Altogether, these techniques, devised to promote healthy alveolar barriers, are vital to enhancing current lung recellularization strategies and the treatment of many edema-associated pulmonary diseases.

There are not enough donor lungs available to meet the increasing demand for lung transplantation. To compound the problem, transplant recipients have a projected survival time of only 5.7 years despite life-long immunosuppression. An alternative approach for acquiring transplantable lungs and reducing post-operative complications may be possible through tissue engineering. Perfusion-decellularization generates natural, three-dimensional extracellular matrix (ECM) scaffolds of an organ that are apt for tissue engineering. Decellularization of the heart, lung, liver, kidney, and pancreas has been reported in animal models and from human tissue. Decellularization of fibrotic and emphysematic lungs indicated that this technique can efficiently remove cells from diseased tissue—a potential source of materials for engineering of transplantable lung tissue. Pulmonary hypertension (PHT) is a vascular disease characterized by increased pulmonary vascular resistance leading to right heart failure and death. Lungs damaged by PHT are unsuitable for transplantation; however, decellularization of these organs may provide scaffolds appropriate for ex vivo lung engineering. Monocrotaline-induced PHT (MCT-PHT) is a well-established model of this disease in rats closely resembling the clinical presentation of PHT in humans. Thus, decellularization and recellularization of hypertensive lungs was evaluated using the MCT-PHT model. Decellularization of control and MCT-PHT Sprague-Dawley rat lungs was accomplished by treating the lungs with Triton X-100, sodium deoxycholate (SDC), NaCl, and DNase. The resulting acellular matrices were extensively characterized by molecular, mechanical, and structural analyses revealing that decellularization was able to remove cells while leaving the ECM components and lung ultrastructure intact; however, the vasculature of MCT-PHT acellular lung scaffolds was narrower than control scaffolds—a hallmark of PHT. To evaluate the effect of narrowed vasculature on the use of hypertensive lungs for tissue engineering, an optimal vascular recellularization technique was developed. Gravity-based seeding of endothelial cells followed by bioreactor-based whole-organ culture resulted in efficient vascular recellularization of control lung scaffolds. However, this method led to heterogeneous re-endothelialization of the vasculature of MCT-PHT matrices suggesting that additional manipulation or optimization is required. / acase@tulane.edu

A busca por técnicas alternativas para suprir a escassez de tecidos e órgãos danificados levou ao surgimento da engenharia de tecidos. Scaffolds biológicos criados a partir da matriz extracelular (MEC) de órgãos e tecidos tem sido uma promissora ferramenta aplicada para suprir esta necessidade. A matriz extracelular placentária descelularizada surge como uma potencial ferramenta para a produção de scaffolds biológicos para recelularização e implantação em áreas lesionadas. Para ser classificado como um scaffolds biológico ideal, a matriz extracelular deve ser acelular e ter preservada suas proteínas e características físicas para viabilizar a adesão celular. Neste contexto, desenvolvemos o scaffolds biológico descelularizado a partir de placentas caninas com 35 e 40 dias de gestação. A eficiência da descelularização foi confirmada pela ausência de conteúdo celular e quantidade de DNA remanescente. A arquitetura vascular e as proteínas da matriz extracelular, tais como, colágenos tipo I, III e IV, laminina e fibronectina, foram preservadas. Para o processo de recelularização, utilizamos células-tronco progenitoras endoteliais derivadas do saco vitelino canino (SVC) e células tronco mesenquimais (CTMs) derivadas de medula óssea canina (CMOC) e de polpa de dente canina (CPDC). O processo de recelularização em placas não aderentes por 7 e 14 dias, na presença do scaffolds placentário secos em ponto crítico auxiliou na eficiência da recelularização, comprovada por imunofluorescência e microscopia eletrônica de varredura, evidenciando a adesão das células no scaffolds e comprovando ser um promissor biomaterial para utilização na medicina regenerativa tecidual. / The search for alternative techniques to address the scarcity of damaged tissues and organs has led to the emergence of tissue engineering. Biological scaffolds created from the extracellular matrix (ECM) of organs and tissues have been a promising applied tool to meet this need. The decellularized placental extracellular matrix appears as a potential tool for the production of biological scaffolds for recellularization and implantation in injured areas. To be classified as an ideal biological scaffold, the extracellular matrix must be acellular and have preserved its proteins and physical characteristics to enable cell adhesion. In this context, we developed the biological scaffold decellularized from canine placentas with 35 and 40 days of gestation. The efficiency of the decellularization was confirmed by the absence of cellular content and amount of DNA remaining. Vascular architecture and extracellular matrix proteins, such as collagens type I, III and IV, laminin and fibronectin, have been preserved. For the process of recellularization, we used stem cells derived from the canine yolk sac (CYSC) and mesenchymal stem cells (MSCs) derived from canine bone marrow (CBMC) and canine dental pulp (CDPC). The process of recellularization in non-adherent plaques for 7 and 14 days in the presence of placental scaffold dried at a critical point assisted in the efficiency of the recellularization, evidenced by immunocytochemistry and scanning electron microscopy, evidencing the adhesion of the cells in the scaffold and proving to be a promising biomaterial for use in tissue regenerative medicine.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20280号 / 医博第4239号 / 新制||医||1021(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 川口 義弥, 教授 羽賀 博典, 教授 坂井 義治 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・論文博士 / 博士(医学) / 乙第13634号 / 論医博第2325号 / 新制||医||1074(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 尾野 亘, 教授 伊達 洋至, 教授 安達 泰治 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

Heart failure is one of the leading causes of death in the United States. Every year in the United States, more than 800,000 people are diagnosed with heart failure and more than 375,000 people die from heart disease. Current therapies such as heart transplants and bioartificial hearts are helpful, but not optimal. Decellularization of porcine whole hearts followed by recellularization with patient-specific human cells may provide the ultimate solution for patients with heart failure. Great progress has been made in the development of efficient processes for decellularization, and the design of automated bioreactors. In this study, the decellularization of porcine hearts was accomplished in 24 h with only 6 h of sodium dodecyl sulfate (SDS) exposure and 98% DNA removal. Automatically controlling the pressure during decellularization reduced the detergent exposure time while still completely removing immunogenic cell debris. Stimulation of macrophages was greatly reduced when comparing native tissue samples to the processed ECM. Complete cell removal was confirmed by analysis of DNA content. General collagen and elastin preservation was demonstrated by SEM and histology. The compression elastic modulus of the ECM after decellularization was lower than native at low strains but there was no significant difference at high strains. Polyurethane casts of the vasculature of native and decellularized hearts demonstrated that the microvasculature network was preserved after decellularization. A static blood thrombosis assay using bovine blood was also developed. A perfusion bioreactor was designed and right ventricle of the decellularized hearts were recellularized with human endothelial cells and cardiac fibroblasts. An effective, reliable, and relatively inexpensive assay based on human blood hemolysis was developed for determining the remaining cytotoxicity of the cECM and the results were consistent with a standard live/dead assay using MS1 endothelial cells incubated with the cECM. Samples from the left ventricle of the hearts were prepared with 300 µm thickness, mounted on 10 mm round glass coverslips. Human induced pluripotent stem cells were differentiated into cardiomyocytes (CMs) and 4 days after differentiation, cardiac progenitors were seeded onto the decellularized cardiac slices. After 10 days, the tissues started to beat spontaneously. Immunofluorescence images showed confluent coverage of CMs on the decellularized slices and the effect of the scaffold was evident in the arrangement of the CMs in the direction of fibers. This study demonstrated the biocompatibility of decellularized porcine hearts with human CMs and the potential of these scaffolds for cardiac tissue engineering. Further studies can be directed toward 3D perfusion recellularization of the hearts and improving repopulation of the scaffolds with various cell types as well as adding mechanical and electrical stimulations to obtain more mature CMs.