The Effects of TiO2 Nanodot Films with RGD Immobilization on Light-Induced Cell Sheet Technology

Cell Sheet Technology as an Engineering-Based Approach to Bone Regeneration

Bone defects that are congenital or the result of infection, malignancy, or trauma represent a challenge to the global healthcare system. To address this issue, multiple research groups have been developing novel cell sheet technology (CST)-based approaches to promote bone regeneration. These methods hold promise for use in regenerative medicine because they preserve cell-cell contacts, cell-extracellular matrix interactions, and the protein makeup of cell membranes. This review introduces the concept and preparation system of the cell sheet (CS), explores the application of CST in bone regeneration, highlights the current states of the bone regeneration via CST, and offers perspectives on the challenges and future research direction of translating current knowledge from the lab to the clinic.

Nanomaterial-based cell sheet technology for regenerative medicine and tissue engineering

Nanomaterial-based cell sheet technology has been reported to be an effective method in regenerative medicine and tissue engineering. Here, we summarized several types of nanomaterials used to harvest cell sheets. Currently, the technology is divided into four categories according to the mechanisms: light-induced cell sheet technology, thermo-responsive cell sheet technology, magnetic-controlled cell sheet technology, and reactive oxygen species (ROS)-induced cell sheet technology. Furthermore, some studies have been conducted to show that nanomaterial-based cell sheets produce satisfying outcomes in the regeneration of bone, skeletal muscle, cardiac tissue, and tendon, as well as angiogenesis and osseointegration. Nevertheless, some shortcomings still exist, such as comprehensive preparation, unclear safety, and cell quality. Thus, future studies should aim to produce more types of nanomaterials to solve this problem.

Recent advances in light-induced cell sheet technology

Various stimuli have been applied to harvest complete cell sheets, including temperature, magnetic, pH, and electrical stimuli. Cell sheet technology is a convenient and efficient approach with beneficial effects for tissue regeneration and cell therapy. Lights of different wavelengths, such as ultraviolet (UV), visible light, and near infrared ray (NIR) light, were confirmed to aid in fabricating a cell sheet. Changes in the wettability, potential, or water content of the culturing surfaces that occur under light illumination induce conformational changes in the adhesive proteins or collagens, which then leads to cell sheet detachment. However, the current approaches face several limitations, as few standards for safe light illumination have been proposed to date, and require a careful control of the wavelength, power, and irradiation time. Future studies should aim at generating new materials for culturing and releasing cell sheets rapidly and effectively.

Controlled Release of Naringin in GelMA-Incorporated Rutile Nanorod Films to Regulate Osteogenic Differentiation of Mesenchymal Stem Cells

Naringin, a Chinese herbal medicine, has been demonstrated to concentration-dependently promote osteogenic differentiation of mesenchymal stem cells (MSCs). However, it remains a challenge to load naringin on coatings for osteogenesis and further control the release kinetics. Here, we demonstrated that the release behavior of naringin on rutile nanorod films could be controlled by either mixing naringin with gelatin methacryloyl (GelMA) before spinning onto the films or soaking the obtained GelMA-incorporated films with the naringin solution to achieve the distinct degradation-type release and diffusion-type release, respectively. We further revealed that the naringin-loaded coatings facilitated adhesion, proliferation and late differentiation, and mineralization of MSCs. Our findings provided a novel strategy to engineer the coatings with controlled release of naringin and emphasized the bioactivity of naringin for the osteogenic differentiation of MSCs.

Recent advances in cell sheet technology for bone and cartilage regeneration: from preparation to application

Bone defects caused by trauma, tumour resection, infection and congenital deformities, together with articular cartilage defects and cartilage-subchondral bone complex defects caused by trauma and degenerative diseases, remain great challenges for clinicians. Novel strategies utilising cell sheet technology to enhance bone and cartilage regeneration are being developed. The cell sheet technology has shown great clinical potential in regenerative medicine due to its effective preservation of cell-cell connections and extracellular matrix and its scaffold-free nature. This review will first introduce several widely used cell sheet preparation systems, including traditional approaches and recent improvements, as well as their advantages and shortcomings. Recent advances in utilising cell sheet technology to regenerate bone or cartilage defects and bone-cartilage complex defects will be reviewed. The key challenges and future research directions for the application of cell sheet technology in bone and cartilage regeneration will also be discussed.

SiO2/TiO2 Nanocomposite Films on Polystyrene for Light-Induced Cell Detachment Application

Light-induced cell detachment shows much potential in in vitro cell culture and calls for high-performance light-responsive films. In this study, a smooth and dense SiO₂/TiO₂ nanocomposite thin film with thickness of around 250 nm was first fabricated on H₂O₂ treated polystyrene (PS) substrate via a low-temperature sol-gel method. It was observed that the film could well-adhere on the PS surface and the bonding strength became increasingly high with the increase of SiO₂ content. The peeling strength and shear strength reached 3.05 and 30.02 MPa, respectively. It was observed the surface of the film could transform into superhydrophilic upon 20 min illumination of ultraviolet with a wavelength of 365 nm (UV365). In cell culture, cells, i.e., NIH3T3 and MC3T3-E1 cells, cultured on SiO₂/TiO₂ nanocomposite film were easily detached after 10 min of UV365 illumination; the detachment rates reached 90.8% and 88.6%, respectively. Correspondingly, continuous cell sheets with good viability were also easily obtained through the same way. The present work shows that SiO₂/TiO₂ nanocomposite thin film could be easily prepared on polymeric surface at low temperature. The corresponding film exhibits excellent biocompatibility, high bonding strength, and good light responses. It could be a good candidate for the surface of cell culture utensils with light-induced cell detachment property.