Noninvasive cross-sectional observation of three-dimensional cell sheet-tissue-fabrication by optical coherence tomography

Measurement of the Adipose Stem Cells Cell Sheets Transmittance

In the field of cell therapy, the interest in cell sheet technology is increasing. To determine the cell sheet harvesting time requires experience and practice, and different factors could change the harvesting time (variability among donors and culture media, between cell culture dishes, initial cell seeding density). We have developed a device that can measure the transmittance of the multilayer cell sheets, using a light emitting diode and a light detector, to estimate the harvesting time. The transmittance of the adipose stromal cells cell sheets (ASCCS) was measured every other day as soon as the cells were confluent, up to 12 days. The ASCCS, from three different initial seeding densities, were harvested at 8, 10, and 12 days after seeding. Real-time PCR and immunostaining confirmed the expression of specific cell markers (CD29, CD73, CD90, CD105, HLA-A, HLA-DR), but less than the isolated adipose stromal cells. The number of cells per cell sheets, the average thickness per cell sheet, and the corresponding transmittance showed no correlation. Decrease of the transmittance seems to be correlated with the cell sheet maturation. For the first time, we are reporting the success development of a device to estimate ASCCS harvesting time based on their transmittance.

Clonal Isolation of Human Pluripotent Stem Cells on Nanofibrous Substrates Reveals an Advanced Subclone for Cardiomyocyte Differentiation

Human pluripotent stem cells (hPSCs) have been widely used for various applications including disease modeling and regenerative medicine, among others. Recently, an increasing number of studies has focused on heterogeneity among hPSCs, which could affect cell quality and subsequent applications. In this study, a nanofibrous platform is developed for single human induced pluripotent stem cell isolation and culture. One type of single cell-derived subclone is established and found to have a distinct morphology compared to other subclones. When used for differentiation toward cardiomyocytes, this type of subclone demonstrates higher differentiation efficiency, increased maturation, and stronger beating compared to those derived from the other subclones. The findings provide a convenient method for single-cell isolation and culture, and demonstrate that variations in differentiation tendencies exist among subclones from the same cell line. This substrate adhesion-based selection process could be used to obtain cell lines with improved differentiation efficiency toward cardiomyocytes and other cell types, which would be advantageous for studies in various fields.

Three-Dimensional Human Cardiac Tissue Engineered by Centrifugation of Stacked Cell Sheets and Cross-Sectional Observation of Its Synchronous Beatings by Optical Coherence Tomography

Three-dimensional (3D) tissues are engineered by stacking cell sheets, and these tissues have been applied in clinical regenerative therapies. The optimal fabrication technique of 3D human tissues and the real-time observation system for these tissues are important in tissue engineering, regenerative medicine, cardiac physiology, and the safety testing of candidate chemicals. In this study, for aiming the clinical application, 3D human cardiac tissues were rapidly fabricated by human induced pluripotent stem (iPS) cell-derived cardiac cell sheets with centrifugation, and the structures and beatings in the cardiac tissues were observed cross-sectionally and noninvasively by two optical coherence tomography (OCT) systems. The fabrication time was reduced to approximately one-quarter by centrifugation. The cross-sectional observation showed that multilayered cardiac cell sheets adhered tightly just after centrifugation. Additionally, the cross-sectional transmissions of beatings within multilayered human cardiac tissues were clearly detected by OCT. The observation showed the synchronous beatings of the thicker 3D human cardiac tissues, which were fabricated rapidly by cell sheet technology and centrifugation. The rapid tissue-fabrication technique and OCT technology will show a powerful potential in cardiac tissue engineering, regenerative medicine, and drug discovery research.