Preparation and in vitro analysis of microencapsulated genetically engineered E. coli DH5 cells for urea and ammonia removal

Abstract

This article describes a novel method of urea and ammonia removal using microencapsulated, genetically engineered Escherichia coli DH5 cells. Optimization of bacterial cell encapsulation was carried out. The optimal method consists of alginate 2.00% (w/v) at a flow rate of 0.0724 mL/min and a coaxial air flow rate of 2.00 L/min. This produces spherical, alginate-poly-L-lysine-alginate (APA) microcapsules of an average 500 +/- 45 mum diameter. Increasing the concentration of alginate from 1.00% to 1.75% improves the quality of the microcapsules, while cell viability remains unaffected. The APA microcapsules are mechanically stable up to 210-rpm agitation with no bacterial cell leakage. The in vitro performance of urea and ammonia removal by encapsulated bacteria is assessed. One hundred milligrams of bacterial cells in APA microcapsules, in their log phase state of growth, can lower 87.89 +/- 2.25% of the plasma urea within 20 min and 99.99% in 30 min. The same amount of encapsulated bacteria can also lower ammonia from 975.14 +/- 70.15 muM/L to 81.151 +/- 7.37 muM/L in 30 min. There are no significant differences in depletion profiles by free and encapsulated bacteria for urea and ammonia removal. This novel approach using microencapsulated, genetically engineered E. coli cells is significantly more efficient than presently available methods of urea and ammonia removal. For instance, it is 30 times more efficient than the standard urease-ammonium adsorbent system. (c) 1995 John Wiley & Sons, Inc.

Artificial Cell Biotechnology for Medical Applications

“…Our in vitro results [25] show that 40.00 B 8.60 g of encapsulated E. coli DH5 can remove 40 g of urea (100 mg/dl in 40 liters). There was no increase in the ammonia level.…”

“…Prakash and Chang [23][24][25] therefore studied the oral use of microencapsulated genetically engineered nonpathogenic Escherichia coli DH5 cells containing Klebsiella aerogenes urease gene in rats with renal failure.…”

Microencapsulated Stem Cells for Tissue Repairing: Implications in Cell-Based Myocardial Therapy

“…The alginate-poly-l-lysine (PLL) system used here utilizes the natural polymer alginate, but the challenge in producing such uniform capsules is to ensure excellent repeatability and reproducibility both within and between batches. The technique used to produce alginate-PLLalginate (APA) capsules is based on the entrapment of individual cells or tissue in an alginate droplet that is then transformed into a rigid bead by gelation in a Ca 2+ -rich solution [17,26].…”

“…Thus, micro encapsulation of cells is currently being studied extensively to confront the limitations of traditional immobilization technologies. Artificial cell microencapsulation is used to encapsulate biologically active materials in specialized ultra-thin semipermeable polymer membranes [4,17]. The principle of mammalian cell microencapsulation is that the permeability of the membrane is engineered to allow the passage of oxygen, important nutrients and cellular products, but stops the ingress of immunoglobulins or immune cells responsible for transplant rejection [18].…”

Artificial Cell Therapy: New Strategies for the Therapeutic Delivery of Live Bacteria

“…The conventional APA microcapsule has thus been shown to pose limitations for general use in the oral administration of microencapsulated bacterial cells for therapy. Some studies have shown that this classic formulation has inadequate stability in the GI tract for some applications [106], while other researchers have shown that APA microcapsules have a controversial permeability [107]. Furthermore, it has been reported that it is difficult to obtain a membrane, optimizing all the properties requested for a successful clinical application, by the process of binary polyelectrolyte complexation [108].…”