Immobilization of Rhodococcus Erythropolis as a Potential Treatment for Atherosclerosis

Cardiovascular disease is the leading cause of death in the United States and isprimarily due to hypercholesterolemia. The novel approach of combatting atherosclerosis presented in this research entails delivery of microencapsulated Rhodococcus erythropolis immobilized in biodegradable alginate-based microcapsules and utilizing the bacterium\u27s cholesterol oxidase enzyme pathway to degrade cholesterol from intermediate-stage arterial plaque. The bacterial growth medium was optimized using Taguchi design methods to enable growth characterizations hindered by biosurfactant by-product. Methodologies for extraction and quantification of biosurfactant and cholesterol were developed and conducted simultaneous to bacterial growth assessment. Bacteria were encapsulated using atomization (850±50 μm) and inkjet bioprinting (32±5 μm) to study the effects of cell density and capsule miniaturization on the rate of cholesterol degradation. The cholesterol degradation rate was determined to be independent of cell density, and capsule miniaturization led to a near 4-fold increase in cholesterol degradation, thus allowing for 61.8% cholesterol in an intermediate-stage lesion to be degraded

Immobilization of R. erythropolis in alginate-based artificial cells for simulated plaque degradation in aqueous media

Cholesterol degradation rates of free and immobilized Rhodococcus erythropolis (ATCC # 25544) were studied utilizing the bacterium’s cholesterol oxidase enzyme pathway to degrade cholesterol in an aqueous simulated non-calcified plaque solution. An L16 (45) Taguchi design was used to minimize the glycolipid bio-surfactant by-product in the growth medium, to improve bacterial viability in the immobilized state. As an expected outcome of miniaturization, there is a significant difference between the atomized (d = 850 ± 50 μm) and inkjet-bioprinted (d = 32 ± 5 μm) lumped kinetic degradation rates after 48 h (p = 0.029, α = 0.05) per ml of jetted alginate. Based on a biphasic cholesterol degradation model, at an initial bacterial cell density of Nlow = 4.53 × 108/ml, for an initial cholesterol concentration of 3 mg/ml, the percentage mass of metabolite degraded is 37.0% ± 0.42%, 57.8% ± 0.04% and 65.1% ± 0.01% for the free, atomized and inkjet immobilized bacteria, respectively