Noninvasive ultrasound imaging for assessment of intact microstructure of extracellular matrix in tissue engineering.

Development of artificial tissues or organs is one of the actual tasks in regenerative medicine that requires observation and evaluation of intact volume microstructure of tissue engineering products at all stages of their formation, from native donor tissues and decellularized scaffolds to recipient cell migration in the matrix. Unfortunately in practice, methods of vital noninvasive imaging of volume microstructure in matrixes are absent. In this work, we propose a new approach based on high-frequency acoustic microscopy for noninvasive evaluation and visualization of volume microstructure in tissue engineering products. The results present the ultrasound characterization of native rat diaphragms and lungs and their decellularized scaffolds. Verification of the method for visualization of tissue formation in the matrix volume was described in the model samples of diaphragm scaffolds with stepwise collagenization. Results demonstrate acoustic microscopic sensitivity to cell content concentration, variation in local density, and orientation of protein fibers in the volume, micron air inclusions, and other inhomogeneities of matrixes.

Biophysical methods for quality evaluation of decellularized and recellularized tissue-engineered constructs of organs and tissues.

Tissue engineering is rapidly growing now and can become a promising alternative to transplantation of organs and tissues, as it is devoid of major shortcomings of transplantology, such as acute shortage, complexity of selection, delivery and storage of donor material, lifelong immunosuppressive therapy. One of the most widely known methods of obtaining biological scaffolds for the subsequent creation of tissue-engineered constructs of organs and tissues is decellularization. The evaluation of the quality of the obtained scaffolds, based on the study of the viability of cell structures in decellularized and recellularized matrices, is one of the priorities of modern regenerative medicine worldwide. In this investigation, the biophysical criteria of decellularization and recellularization of tissue-engineered constructs based on the evaluation of the generation of free radicals in native, decellularized and recellularized tissues by EPR spectroscopy and chemoluminescence in a complex assessment of the quality of biological matrixes obtained are considered using intrathoracic organs and tissues of rats. It has been established that the intensity indices of free radical generation in native and recellularized tissues of animal organs, as well as in decellularized matrices, can serve as one of the express criteria for quantitative assessment of cell structures viability.

The Use of Mathematical Modelling for Improving the Tissue Engineering of Organs and Stem Cell Therapy.

Regenerative medicine is a multidisciplinary field where continued progress relies on the incorporation of a diverse set of technologies from a wide range of disciplines within medicine, science and engineering. This review describes how one such technique, mathematical modelling, can be utilised to improve the tissue engineering of organs and stem cell therapy. Several case studies, taken from research carried out by our group, ACTREM, demonstrate the utility of mechanistic mathematical models to help aid the design and optimisation of protocols in regenerative medicine.

Orthotopic transplantation of a tissue engineered diaphragm in rats.

The currently available surgical options to repair the diaphragm are associated with significant risks of defect recurrence, lack of growth potential and restored functionality. A tissue engineered diaphragm has the potential to improve surgical outcomes for patients with congenital or acquired disorders. Here we show that decellularized diaphragmatic tissue reseeded with bone marrow mesenchymal stromal cells (BM-MSCs) facilitates in situ regeneration of functional tissue. A novel bioreactor, using simultaneous perfusion and agitation, was used to rapidly decellularize rat diaphragms. The scaffolds retained architecture and mechanical properties and supported cell adhesion, proliferation and differentiation. Biocompatibility was further confirmed in vitro and in vivo. We replaced 80% of the left hemidiaphragm with reseeded diaphragmatic scaffolds. After three weeks, transplanted animals gained 32% weight, showed myography, spirometry parameters, and histological evaluations similar to native rats. In conclusion, our study suggested that reseeded decellularized diaphragmatic tissue appears to be a promising option for patients in need of diaphragmatic reconstruction.

Whole organ and tissue reconstruction in thoracic regenerative surgery.

Development of novel prognostic, diagnostic, and treatment options will provide major benefits for millions of patients with acute or chronic respiratory dysfunction, cardiac-related disorders, esophageal problems, or other diseases in the thorax. Allogeneic organ transplant is currently available. However, it remains a trap because of its dependency on a very limited supply of donated organs, which may be needed for both initial and subsequent transplants. Furthermore, it requires lifelong treatment with immunosuppressants, which are associated with adverse effects. Despite early clinical applications of bioengineered organs and tissues, routine implementation is still far off. For this review, we searched the PubMed, MEDLINE, and Ovid databases for the following keywords for each tissue or organ: tissue engineering, biological and synthetic scaffold/graft, acellular and decelluar(ized), reseeding, bioreactor, tissue replacement, and transplantation. We identified the current state-of-the-art practices in tissue engineering with a focus on advances during the past 5 years. We discuss advantages and disadvantages of biological and synthetic solutions and introduce novel strategies and technologies for the field. The ethical challenges of innovation in this area are also reviewed.