Tissue engineering of urethra: Systematic review of recent literature.

The purpose of this article was to perform a systematic review of the recent literature on urethral tissue engineering. A total of 31 articles describing the use of tissue engineering for urethra reconstruction were included. The obtained results were discussed in three groups: cells, scaffolds, and clinical results of urethral reconstructions using these components. Stem cells of different origin were used in many experimental studies, but only autologous urothelial cells, fibroblasts, and keratinocytes were applied in clinical trials. Natural and synthetic scaffolds were studied in the context of urethral tissue engineering. The main advantage of synthetic ones is the fact that they can be obtained in unlimited amount and modified by different techniques, but scaffolds of natural origin normally contain chemical groups and bioactive proteins which increase the cell attachment and may promote the cell proliferation and differentiation. The most promising are smart scaffolds delivering different bioactive molecules or those that can be tubularized. In two clinical trials, only onlay-fashioned transplants were used for urethral reconstruction. However, the very promising results were obtained from animal studies where tubularized scaffolds, both non-seeded and cell-seeded, were applied. Impact statement The main goal of this article was to perform a systematic review of the recent literature on urethral tissue engineering. It summarizes the most recent information about cells, seeded or non-seeded scaffolds and clinical application with respect to regeneration of urethra.

Toxicity testing and drug screening using iPSC-derived hepatocytes, cardiomyocytes, and neural cells.

Unexpected toxicity in areas such as cardiotoxicity, hepatotoxicity, and neurotoxicity is a serious complication of clinical therapy and one of the key causes for failure of promising drug candidates in development. Animal studies have been widely used for toxicology research to provide preclinical security evaluation of various therapeutic agents under development. Species differences in drug penetration of the blood-brain barrier, drug metabolism, and related toxicity contribute to failure of drug trials from animal models to human. The existing system for drug discovery has relied on immortalized cell lines, animal models of human disease, and clinical trials in humans. Moreover, drug candidates that are passed as being safe in the preclinical stage often show toxic effects during the clinical stage. Only around 16% drugs are approved for human use. Research on induced pluripotent stem cells (iPSCs) promises to enhance drug discovery and development by providing simple, reproducible, and economically effective tools for drug toxicity screening under development and, on the other hand, for studying the disease mechanism and pathways. In this review, we provide an overview of basic information about iPSCs, and discuss efforts aimed at the use of iPSC-derived hepatocytes, cardiomyocytes, and neural cells in drug discovery and toxicity testing.

Recent approaches and challenges in iPSCs: modeling and cell-based therapy of Alzheimer's disease.

The lack of effective therapies for different neurodegenerative disorders has placed huge burdens on society. To overcome the restricted capacity of the central nervous system for regeneration, the promising alternative would be to use stem cells for more effective treatment of chronic degenerative and inflammatory neurological conditions and also of acute neuronal damage and from injuries or cerebrovascular diseases. The generation of induced pluripotent stem cells from somatic cells by the ectopic expression of specific transcription factors has provided the regenerative medicine field with a new tool for investigating and treating neurodegenerative diseases, including Alzheimer's disease (AD). This technology provides an alternative to traditional approaches, such as nuclear transfer and somatic cell fusion using embryonic stem cells. However, due to a problem in standardization of certain reprogramming techniques and systems research, the induced pluripotent stem cell-based technology is still in its infancy. The present paper is aimed at a brief review of the current status in modeling and cell-based therapies for AD.

The effect of salivary gland extract of Lucilia sericata maggots on human dermal fibroblast proliferation within collagen/hyaluronan membrane in vitro: transmission electron microscopy study.

BACKGROUND: Lucilia sericata maggots are applied to chronic wounds to aid healing when conventional treatments have failed. After their application into a necrotic wound, they potentially influence wound healing with a combination of specific proteinases that are involved in the remodeling of extracellular matrix. These proteases cause changes in fibroblast adhesion and spread upon extracellular matrix protein surfaces, affecting integrity of the protein surfaces-especially fibronectin-while maintaining cell viability. OBJECTIVE: This study focused on in vitro monitoring of the effect of homogenate substances prepared from maggot salivary gland of L sericata on the ultrastructure of human neonatal fibroblasts. METHODS: Collagen/hyaluronan membrane was used as the synthetic substitute of extracellular matrix. The cultured human neonatal fibroblasts B-HNF-1 were seeded on the surface of the collagen/hyaluronan membrane and cultured with maggot salivary gland extract (SGE) at a concentration of 2.4 glands/1 mL. RESULTS: The authors observed increased cell metabolism and protein production (euchromatic nucleus, voluminous nuclear membrane, large reticular nuclei, distended and filled cisterns of rough endoplasmic reticulum, Golgi apparatus with saccules, and vesicles packed with fine fibrillar material) after incubating the cells in culture medium with SGE. CONCLUSION: The authors believe that increased cell metabolism and protein production corresponded with formation of microfibrillar net used for migration of fibroblasts in culture, but mainly for proper production of extracellular matrix. The authors suggest that their results may help explain the effect of SGE on wound healing and support implementation of maggot therapy into human medicine.

Perspectives of induced pluripotent stem cells for cardiovascular system regeneration.

Induced pluripotent stem cells (iPSCs) hold great promise for basic research and regenerative medicine. They offer the same advantages as embryonic stem cells (ESCs) and moreover new perspectives for personalized medicine. iPSCs can be generated from adult somatic tissues by over-expression of a few defined transcription factors, including Oct4, Sox2, Klf4, and c-myc. For regenerative medicine in particular, the technology provides great hope for patients with incurable diseases or potentially fatal disorders such as heart failure. The endogenous regenerative potentials of adult hearts are extremely limited and insufficient to compensate for myocardial loss occurring after myocardial infarction. Recent discoveries have demonstrated that iPSCs have the potential to significantly advance future cardiovascular regenerative therapies. Moreover, iPSCs can be generated from somatic cells of patients with genetic basis for their disease. This human iPSC derivates offer tremendous potential for new disease models. This paper reviews current applications of iPSCs in cardiovascular regenerative medicine and discusses progress in modeling cardiovascular diseases using iPSCs-derived cardiac cells.

The tissue engineering of articular cartilage: cells, scaffolds and stimulating factors.

Damage or loss of articular cartilage as a consequence of congenital anomaly, degenerative joint disease or injury leads to progressive debilitation, which has a negative impact on the quality of life of affected individuals in all age groups. Classical surgical techniques for hyaline cartilage reparation are frequently insufficient and in many cases it is not possible to obtain the expected results. For this reason, researchers and surgeons are forced to find a method to induce complete cartilage repair. Recently, the advent of tissue engineering has provided alternative possibilities for the treatment of these patients by application of cell-based therapy (e.g. chondrocytes and adult stem cells) combined with synthetic substitutes of the extracellular matrix and bioactive factors to prepare functional replacement of hyaline cartilage. This communication is aimed at a brief review of the current status of cartilage tissue engineering and recent advances in the field.

Autologous biograft and mesenchymal stem cells in treatment of the diabetic foot.

OBJECTIVES: This study was performed to test a new technique for treatment of chronic non-healing wound (diabetic ulcer) using autologous biograft composed of autologous skin fibroblasts on biodegradable collagen membrane (Coladerm) in combination with autologous mesenchymal stem cells (MSC) derived from the patient's bone marrow. DESIGN: The bone marrow aspirate of the patient with diabetic foot was applied directly to the wound and injected into the edges of the wound, finally covered with prepared autologous biograft. The patient received two additional treatments with cultured MSC on day 7 and 17. RESULTS: The wound showed a steady overall decrease in wound size and an increase in the vascularity of the dermis and in the dermal thickness of the wound bed after 29 days of combined treatment. CONCLUSIONS: Closing and healing of the non-healing diabetic ulcer was achieved by using the given combined therapy.

Effect of pyridoxylidene aminoguanidine on human diploid cells B-HEF-2: in vitro cytotoxicity test and cytogenetic analysis.

BACKGROUND: Pyridoxylidene aminoguanidine is an appropriate inhibitor of protein glycation, respectively formation of advanced glycation products, which are connected with mechanism of pathogenesis in chronic diabetic complications. Moreover, it was found that in comparison with aminoguanidine, pyridoxylidene aminoguanidine does not influence the level of vitamin B6 in liver and kidneys in vivo. The aim of this study was to test cytotoxic effect of pyridoxylidene aminoguanidine in vitro, in regard to its potential use as inhibitor of advance protein glycation in diabetic patients. METHODS: The potential genotoxic activity of pyridoxylidene aminoguanidine in vitro was assessed by the micronucleus test and the karyological analysis. The direct contact method using diploid human cell line B-HEF-2 was performed to evaluate cytotoxicity. The concentrations of 5 x 10(-3), 2.5 x 10(-3) and 1 x 10(-3) ml/l were used in all tests. RESULTS: Microscopic analysis did not proved any changes in morphology of exposed fibroblasts. The inhibitive effect of pyridoxylidene aminoguanidine was increased with rising concentration. The proliferative activity of exposed cells to concentrations of 1 x 10(-3), 2.5 x 10(-3), 5 x 10(-3) mol/l was inhibited approximately by 30%, 60% and 80%, respectively. The frequency of micronuclei and rate of numerical or structural aberrations was not increased. CONCLUSION: Obtained results confirmed that pyridoxylidene aminoguanidine in selected concentrations has an inhibitive effect on the proliferation activity of exposed cells, but did not develop any cytotoxic effect on B-HEF-2 cells.