Artificial cells microencapsulated genetically engineered E. coli DH5 cells for the lowering of plasma creatinine in-vitro and in-vivo

Phenylketonuria: a review of current and future treatments

Phenylketonuria (PKU) is an autosomal recessive inborn error of metabolism caused by a deficiency in the hepatic enzyme phenylalanine hydroxylase (PAH). If left untreated, the main clinical feature is intellectual disability. Treatment, which includes a low Phe diet supplemented with amino acid formulas, commences soon after diagnosis within the first weeks of life. Although dietary treatment has been successful in preventing intellectual disability in early treated PKU patients, there are major issues with dietary compliance due to palatability of the diet. Other potential issues associated with dietary therapy include nutritional deficiencies especially vitamin D and B12. Suboptimal outcomes in cognitive and executive functioning have been reported in patients who adhere poorly to dietary therapy. There have been continuous attempts at improving the quality of medical foods including their palatability. Advances in dietary therapy such as the use of large neutral amino acids (LNAA) and glycomacropeptides (GMP; found within the whey fraction of bovine milk) have been explored. Gene therapy and enzyme replacement or substitution therapy have yielded more promising data in the recent years. In this review the current and possible future treatments for PKU are discussed.

The use of hollow fiber membranes combined with cytometry in analysis of bacteriological samples

To avoid destruction of the implanted biological material it may be separated from host immunological system by enclosure within a permiselective membrane. Two-directional diffusion through the membrane of nutrients, metabolic products, as well as bioactive products of encapsulated cells is required to ensure their survival and functional activities. The system of cells encapsulated within the membrane releasing the biologically active substance may be applied either locally to give an opportunity of therapeutic agent activity in the specified place and/or at some convenient site (tissue) for a prolonged period of time.The novel system of bacteria bio-encapsulation using modified membranes, and its assessment by flow cytometry is described and discussed. The encapsulated in membrane bacteria, functioning and releasing their products were evaluated in the systems in vitro and in vivo. The bacteria cells products impact on Eukariotic cells was evaluated. The cytometric evaluation demonstrates the membrane ability to avoid the release of bacteria enclosed within the membrane wall. In experiments with treatment of the bacteria with antibiotic to release products from damaged bacteria it was possible to distinguish stages of the applied antibiotic impact on encapsulated bacteria cells. In E. coli following stages were distinguished: induction of membrane permeability to PI, activation of proteases targeting GFP (protein) and subsequent nucleic acids degradation. In the another experiment the evidence was presented of the cytotoxic activity of live Bacillus subtilis encapsulated within the membrane system. The Bacilus products mediated by secreted listeriolysin O (LLO) on the chosen eukaryotic cells was evaluated. Similar systems releasing bacterial products locally and continuously may selectively affect different types of cells and may have possible application in the anticancer treatment at localized sites.

Microencapsulated stem cells for tissue repairing: implications in cell-based myocardial therapy

Stem cells have the unique properties of self-renewal, pluripotency and a high proliferative capability, which contributes to a large biomass potential. Hence, these cells act as a useful source for acquiring renewable adult cell lines. This, in turn, acts as a potent therapeutic tool to treat various diseases related to the heart, liver and kidney, as well as neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease. However, a major problem that must be overcome before it can be effectively implemented into the clinical setting is a suitable delivery system that can retain an optimal quantity of the cells at the targeted site for a maximal clinical benefit; a system that will give a mechanical as well as an immune protection to the foreign cells, while at the same time enhancing the yields of differentiated cells, maintaining cell microenvironments and sustaining the differentiated cell functions. To address this issue we opted for a novel delivery system, termed the ‘artificial cells’, which are semipermeable microcapsules with strong and thin multilayer membrane components with specific mass transport properties. Here, we briefly introduce the concept of artificial cells for encapsulation of stem cells and investigate the application of microencapsulation technology as an ideal tool for all stem transplantations and relate their role to the emerging field of cellular cardiomyoplasty.

Evaluation of Two Protocols of Uremic Rat Model: Partial Nephrectomy and Infarction

Animal models of chronic renal failure have been mostly achieved by partial ablation of renal parenchyma, the two most common techniques employed being surgical resection or infarction. Evaluation of the uremic model using these two techniques was carried out in Wistar rats. Two weeks after operative procedure, measured serum urea levels in the resection and infarction models were 59.1 and 64.3 mg/dL (normal range 15.6-24.4 mg/dL) respectively. However, the standard deviation in the former was significantly lower, 6.3 vs. 97.1 mg/dL from infarction model, p = 0.007. A consistent degree of glomerular filtration rate reduction was obtained in the resection model, resulting in 20-30% of normal creatinine clearance. This compared favorably with the creatinine clearance range (0.3-74% of normal) from the infarction model, in which two animals died of uremia and seven had higher than 50% of normal creatinine clearance. It is reasonable to attribute reproducibility and homogeneity demonstrated in the resection model to (i) more precise control of renal ablation extent with surgical techniques and (ii) less interplay of confounding injury mechanism to remnant kidney. These data support superiority of the resection model as an experimental tool for pathophysiological and/or interventional investigations of chronic renal failure.

Recombinant Saccharomyces cerevisiae strain expressing a model cytochrome P450 in the rat digestive environment: viability and bioconversion activity

An innovative "biodrug" concept, based on the oral administration of living recombinant microorganisms, has recently emerged for the prevention or treatment of various diseases. An engineered Saccharomyces cerevisiae strain expressing plant P450 73A1 (cinnamate-4-hydroxylase [CA4H] activity) was used, and its survival and ability to convert trans-cinnamic acid (CIN) into p-coumaric acid (COU) were investigated in vivo. In rats, the recombinant yeast was resistant to gastric and small intestinal secretions but was more sensitive to the conditions found in the large intestine. After oral administration of yeast and CIN, the CA4H activity was shown in vivo, with COU being found throughout the rat's digestive tract and in its urine. The bioconversion reaction occurred very fast, with most of the COU being produced within the first 5 min. The gastrointestinal sac technique demonstrated that the recombinant yeast was able to convert CIN into COU (conversion rate ranging from 2 to 5%) in all the organs of the rat's digestive tract: stomach, duodenum, jejunum, ileum, cecum, and colon. These results promise new opportunities for the development of drug delivery systems based on engineered yeasts catalyzing a bioconversion reaction directly in the digestive tract.

Probiotics and Prebiotics in Human Health

Probiotic bacteria are found in the intestines of humans and other mammals where they provide health benefits to the host. They do so by (1) providing nutrients and cofactors, (2) successfully competing with pathogens, and (3) stimulating host immune responses by producing specific polysaccharides. These bacteria can also alleviate the symptoms of disease-related metabolic disorders. Prebiotics are substances, usually poorly metabolized polysaccharides and oligosaccharides, that cannot be ingested effectively by the animal. They stimulate the growth of intestinal probiotic bacteria, which can utilize these carbohydrates, thereby promoting health of the organism. Genetic engineering has proven useful for the design of probiotic bacteria that counteract the symptoms of genetic and age-related diseases. Can these bacteria be engineered, through human-promoted accelerative evolution, so that they stimulate their own growth and that of other probiotic bacteria so as to crowd pathogens out of the intestine?

Genetically engineered probiotics

Probiotic micro-organisms have been used for many years. Originating as food supplements, they are now most often administered orally and offer an attractive alternative for treating of intestinal disorders. A better understanding of the mechanisms by which these micro-organisms act has now opened up possibilities for designing new probiotic strains. Through genetic engineering, it is possible not only to strengthen the effects of existing strains, but also to create completely new probiotics. These need not necessarily be composed only of bacterial products but can also include elements of regulatory systems or enzymes derived from a foreign-human-source. If designed carefully and with absolute attention to biological safety in its broadest sense, the development of genetically modified probiotics has the potential to revolutionize alimentary health.

Present status of modified hemoglobin as blood substitutes and oral therapy for end stage renal failure using artificial cells containing genetically engineered cells

Artificial cell or bioencapsulation has been developed for use in bioartificial organs, drug delivery, blood substitutes, and other areas. Recent rapid advances in modified hemoglobin blood substitutes have resulted in advance stages of Phase III clinical trials. Another area of use is in oral therapy, using artificial cells microencapsulated with genetically engineered cells for use in end stage renal failure and other conditions.