Investigation of cell-based therapies employing microcapsules and microspheres: encapsulation and controlled release

Microencapsulation of therapeutic cells has emerged as a major modality to treat a wide range of diseases through protecting the encapsulated cells. However, in spite of numerous refinements in cell encapsulation during the past decades, the strategy still has not met the requirements for practical relevance. Biocompatible microcapsules (MCs) and -spheres (MSs) were fabricated as advanced drug delivery vehicles for various applications. Novel precision particle fabrication (PPF) was employed to prepare MSs and MCs with controlled size and uniformity which are critical parameters in the release kinetics of drugs including therapeutic proteins and cells. Furthermore, core/shell MCs containing therapeutic cells were investigated for feasibility of employing PPF in practical applications. First, we demonstrated the fabrication of MCs with diameters of 120 – 510 μm by crosslinking core/shell microdrops of highly viscous alginate solutions generated from a coaxial nozzle at a rate of 1,000 drops/sec. Controllability of the microdrop size was validated, optimizing the cell confinement in the core. As practical applications, NIH 3T3 fibroblasts or human and pig islets were encapsulated by PPF, exhibiting no cell protrusion or decrease in their viability. Uniform core/shell MCs co-encapsulating poly (ε-caprolactone) MSs with NIH 3T3 fibroblasts as model anchorage dependent cells (ADCs) were designed to increase the survival of the cells via re-establishment of cell-substrate interactions. The core/shell MCs with the altered intracapsular environment resulted in higher cell survival and proliferation when compared to those without the MSs or the alginate/poly-L-lysine/alginate MCs. This study provides a proof of concept of the co-encapsulation of microspheres with therapeutic ADCs. In order to apply such co-encapsulation strategy to islet xenotransplantation for the treatment of type 1 diabetes, we encapsulated porcine islets together with exenatide-loaded poly(latic-co-glycolic acid) MSs to enhance islet survival and function as exenatide locally released in the intracapsular environment. The MCs with exenatide-loaded MSs showed improved glucose-stimulated response. The results indicate that the co-encapsulation concept of exenatide-loaded MSs with porcine islets is a promising strategy for achieving long-term survivability and function of islets, while overcoming donor shortage by reducing the required transplanted islet mass. Microencapsulation and controlled release of Pantoea agglomerans strain E325 (E325), an antagonist to the bacterial plant pathogen Erwinia amylovora that causes fire blight, a devastating disease of apple and pear, have been investigated. To preserve viability and promote proliferation, E325 was encapsulated with nutrients in core/shell MCs. Controlled release of E325 was achieved by separately adjusting alginate concentrations in the shell and core solutions, and by controlling the MC size. Proliferation of E325 within MCs, followed by their subsequent release, and colonization activities on apple flowers were investigated. This study could serve as a model for further studies on development of effective plant disease management strategies. Next, we focused on the feasibility of the MC-mediated treatment for field applications exposed to rapid and wide fluctuations in moisture and nutrient levels and storability of the inoculum. This study demonstrated the following advantages: (1) maintenance of E325 viability in moisture-poor environments including hypanthium, the most common site of infection, (2) improved suppressive activity against the pathogen of fire blight (strain Ea153) at various relative humidity, and (3) long-term survivability through lyoprotection and osmoadaptation.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2016

Author dc:creator

• Kim, In Yong

Contributors dc:contributor

• Kim, Kyekyoon (Kevin)
• Schutt-Ainé, José E.
• Popescu, Gabriel
• Choi, Hyungsoo

• Cell therapy, Drug delivery system, Microspheres, Microcapsules,Core-shell structure
• Co-encapsulation
• Cell encapsulation
• Porcine islets
• Exenatide
• Islet encapsulation
• Xenotransplantation
• Fire blight
• Antogonist
• Microencapsulation
• Biocontrol
• Pantoea agglomerans
• Erwinia amylovora
• Cell release
• Lyoprotection

Statement dc:rights

• Copyright 2016 In Yong Kim

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/92846

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/92846