Adipose-Derived Stem Cells for Tissue Engineering and Regenerative Medicine Applications

Adipose-derived stem cells (ASCs) are a mesenchymal stem cell source with properties of self-renewal and multipotential differentiation. Compared to bone marrow-derived stem cells (BMSCs), ASCs can be derived from more sources and are harvested more easily. Three-dimensional (3D) tissue engineering scaffolds are better able to mimic the in vivo cellular microenvironment, which benefits the localization, attachment, proliferation, and differentiation of ASCs. Therefore, tissue-engineered ASCs are recognized as an attractive substitute for tissue and organ transplantation. In this paper, we review the characteristics of ASCs, as well as the biomaterials and tissue engineering methods used to proliferate and differentiate ASCs in a 3D environment. Clinical applications of tissue-engineered ASCs are also discussed to reveal the potential and feasibility of using tissue-engineered ASCs in regenerative medicine

Microfluidic-based fabrication of microgels for tissue engineering

This thesis presents the experimental and computational study of hydrogel microgels using flow-focusing devices. The microfluidic devices were fabricated to generate microgels from two immiscible phases of fluids. Conventional replica molding and photolithography methods were used to fabricate a rectangular channel microfluidic device. Using the flow-focusing microfluidic devices, effects of various parameters on hydrogel pre-polymer droplet generation were investigated experimentally and computationally. First, three-dimensional (3D) computational simulations were conducted to study the physics of hydrogel pre-polymer droplet formation mechanism in three different regimes: squeezing, dripping, and jetting regime. Subsequently, effects of viscous, inertia and surface tension force on the gelatin methacrylate (GelMA) pre-polymer droplet generation and droplet size were studied through experiments. Finally, based on computational and experimental results, the uniformly controlled size of GelMA microgels was created. All experimental data were summarized by a capillary number of the dispersed and the continuous phases to characterize the different regimes of GelMA pre-polymer droplet generation and to predict the transition of dripping to a jetting regime for GelMA pre-polymer in the flow-focusing device. Also, two types of cells, MCF-7 breast cancer cells, and 3T3 fibroblasts, were mixed in a 5 wt% GelMA pre-polymer solution used as dispersed phase. The uniform cell-laden GelMA microgels were fabricated and the cell viability was over 80%. In addition, a new method to create the polydimethylsiloxane (PDMS) circular channel was developed using a rapid and cheap 3D printing process. Due to the resolution limitation of 3D printing, the channels were elliptical, and subsequent liquid PDMS injection process was adopted to form fully circular channels.Graduate Studies, College of (Okanagan)Graduat

Development of 3D functional brain tissue model

Nervous system disorders including acute traumatic injuries, neurodegenerative diseases, and neurodevelopmental disorders are estimated to affect more than one billion people worldwide. Study and understanding the development of the human nervous system and exposing the mechanisms of mental disorders has greatly been limited due to the restricted access to the functional human brain tissue. 3D in vitro organ models has recently shown to be a powerful tool for biological and medical studies. These models, however, require special 3D construction of cell and extracellular matrixes that are often hard to achieve with conventional fabrication approaches. Bioprinting technique has emerged as potent platform to fabricate these complex 3D models. Here, state-of-art stem cell-based 3D in vitro brain models that recapitulate the geometrical complexity of the brain are developed using 3D bioprinting. The model is developed based on two cell types, neural stem cell and primary astrocytes. To create the model, a high-throughput biofabrication strategy based on embedded 3D bioprinting technology is designed, developed and characterized. Protocols, culture media, bioinks and biomaterials used are tuned and optimized to increase cell viability, enhance cell activity and promote neural stem cell differentiation. The procedures are optimized through a series of 2D and 3D studies and finally, the 3D bioprinted brain in vitro model is carried out. Keywords: Brain tissue, Neural stem cells, Bioprinting, DifferentiationApplied Science, Faculty ofMechanical Engineering, Department ofGraduat

Laser diode-based ultrafast crosslinking of cell-encapsulated gelatin methacrylate hydrogels

Applied Science, Faculty ofNon UBCEngineering, School of (Okanagan)ReviewedFacult